Patent Grant
10870153
The present invention relates to a method for preparation of alloys and compounds based on one or more of Zn, V, Cr, Co, Sn, Ag, Al, Ta, Ni, Fe, Nb Cu, Pt, W, Pd, and Mo, and/or Pb, Sb, Bi, In, Cd, Ga, Rh, Ir, Ru, Os, Re.
Metallic powders based on alloys and compounds of the transition metals can be used in a wide range of industrial applications. Metallic powders are often produced through a multi-step melting process involving melting ingots of the required alloy constituents followed by evaporation or atomisation. The melting route presents significant difficulties in manufacturing many compositions when those alloys include reactive additives. There is also the requirement for an accurate and uniform composition throughout the powder product, and this can be difficult to achieve when the constituting elements have widely differing physical properties.
Some pure metal powders are produced using the carbonyl route, wherein the metal constituents are converted into a gaseous carbonyl that is then heated under conditions appropriate for decomposition into the relevant metal and the product is usually in the form of a powder. This route is used on an industrial scale for production of several materials such as Ni, but is generally not suitable for most alloys.
There is need for a new technology to avoid problems associated with the current indirect melting route for production of alloys and to enable production of high quality powders at low cost. Equally, there is need for a new process that permits formation of compounds that cannot be obtained using current melt routes where the constituting elements are not chemically compatible.
The present disclosure aims to describe a method and an apparatus for producing transition metal, metal alloy or metal compound powders at a low cost.
Herein, unless the contrary intention appears:
For the base metals to which the present invention relates, reduction of the base metal chlorides with Al is highly exothermic and may lead to a thermal runway with excessive increases in the temperature of the reactants. The present invention provides a method for controlling exothermic reactions between base metal chlorides and Al and uses the method for reducing solid metal chlorides based on Zn, V, Cr, Co, Sn, Ag, Ta, Ni, Fe, Nb Cu, Pt, W, Pd, and Mo to their base metals or alloys.
In one form, the process overcomes thermal runway effects due to the exothermic reactions by contacting the base metal halide powder with a control powder and contacting the mixture with the Al reducing agent. The inclusion of the control powder acts to moderate the rate of the exothermic reaction, add thermal mass, and optionally act as a reducing agent to partially reduce the base metal halide as an intermediate. In the following, we refer to base metal chlorides to illustrate the process and explain the various processing steps. However, use of other halides is within the scope of the invention and using the chloride example is not intended as limiting.
The reactions between base metal chlorides and Al may be divided into two steps, wherein the base metal chlorides are mixed and reacted with a control powder based on Zn, V, Cr, Co, Sn, Ag, Ta, Ni, Fe, Nb Cu, Pt, W, Pd, and Mo, and then the resulting intermediate product is reacted with an Al scavenger. The two reaction steps are carried out while providing a combination of control mechanisms, including:
The reduction process may be divided into two stages:
The process can be operated in a full batch mode, in a semi-batch mode or in a full continuous mode.
The present invention comprises several aspects:
In a first aspect, there is provided a method for controlled exothermic reduction of a metal halide of one or more of Zn, V, Cr, Co, Sn, Ag, Ta, Ni, Fe, Nb Cu, Pt, W, Pd, Mo, Pb, Sb, Bi, In, Cd, Ga, Rh, Ir, Ru, Os, and Re, with an Al reducing agent, the method comprising:
The control powder can be a final, fully reduced product of the method, or an intermediate, partly reduced product of the method, or a powder different from the end-product but selected from one or more of the other base metals compatible with the required composition of the required end-product. In a preferred embodiment, the control powder may also include aluminium chlorides, and sublimation of the aluminium chloride acts as a coolant removing heat away from the reaction zone where exothermic chemical reactions are taking place.
In a second aspect, there is provided a two-stage method for producing inorganic powders based on Al, Zn, V, Cr, Co, Sn, Ag, Ta, Ni, Fe, Nb Cu, Pt, W, Pd, and Mo, and/or Pb, Sb, Bi, In, Cd, Ga, Rh, Ir, Ru, Os, Re, wherein:
In a third aspect, there is provided a method for producing catalysts and structured materials, wherein the product is a metal, an alloy or a compound based on one or more the base metals Zn, V, Cr, Co, Sn, Ag, Al, Ta, Ni, Fe, Nb Cu, Pt, W, Pd, and Mo, and/or Pb, Sb, Bi, In, Cd, Ga, Rh, Ir, Ru, Os, Re, and further includes alloying additives. According to the method of this aspect, a base metal or base metal alloy is produced according to the methods of the first aspect or the second aspect, and the method can include the additional step of post processing the resulting base metal alloy powder to induce changes in its composition and/or in its morphology. Means for carrying out the additional step can include dissolving the Al in an alkaline solution or an acidic solution, and reacting the base metal powder with reactive elements such as oxygen, hydrogen, sodium and/or sulphur. The control powder can be a final or intermediate product of the method, or a powder different from the end-product and added with the starting chemicals.
In a fourth aspect, there is provided a method for production of multi-component alloy powders and composites wherein the control powder has a substantially different composition from the elemental composition produced through reduction of the starting base metal chlorides with Al and wherein the final product contains a substantial amount of unreacted control powder; the control powder can be in the form of a powder with a melting temperature higher than 660° C. The control powder forms one component of the product constituents.
Heat may be removed from the reactants to limit temperature increases due to exothermic energy release to a manageable level.
In a fifth aspect of the invention, there is provided a modular apparatus for production of a base metal or base metal alloy powders based on Al, Zn, V, Cr, Co, Sn, Ag, Ta, Ni, Fe, Nb Cu, Pt, W, Pd, and Mo, and/or Pb, Sb, Bi, In, Cd, Ga, Rh, Ir, Ru, Os, Re. The apparatus may comprise:
Typically, the apparatus includes heating/cooling apparatus for controlling the temperature of the reactants within the limits of the required operation and product characteristics. Openings may be provided for the introduction of inert and reactive gases.
Preferably, the apparatus of the fifth aspect of the invention is suitable for implementing the method of any of the aspects of the invention described herein.
One form of the present invention provides a novel method for controlling exothermic reactions between base metal chlorides and Al and a process implementing the method for direct production of base metal or alloy powders starting from low-cost chemicals. The invention overcomes problems usually associated with the melting/atomising route such as segregation and enables production of alloys in qualities that may not be possible through the melt route. The present invention relates to base metals Mb, where all reactions between Al and any stable chloride species based on Mb and Cl (MbClx) leading to the base metal are exothermic at all processing temperatures between 250° C. and 1000° C. corresponding to the processing conditions of the required base metal alloys.
In a most preferred embodiment, the method provides procedures for reducing base metal chlorides of Zn, V, Cr, Co, Sn, Ag, Ta, Ni, Fe, Nb Cu, Pt, W, Pd, and Mo to produce base metal or alloys. The method uses Al as a chlorine scavenger and provides safe and effective means for overcoming difficulties due to the extreme reactivity between Al and the reducible base metal chlorides. The method allows for including additives based on the alloying elements and Al. Embodiments discussed in the following sections describe procedures and rules for implementing the method and for controlling thermal effects due to energy released by the reduction reactions.
The method of the present invention can be operated in batch mode, semi-continuous mode or in continuous mode by exothermically reacting solid base metal chlorides with a control powder and reducing compounds comprising Al. Preferably, the reacting step is carried out through reacting the base metal chlorides with the control powder first and then reacting the resulting mixture with Al. The method provides for separate streams of reducible base metal chlorides and an Al reducing agent to be fed continuously into a reaction zone containing a control powder in a scheme designed to achieve effective management for the heat generated by exothermic reduction between of the reactants.
In one preferred embodiment, the method comprises the steps of mixing and reacting a first stream of reducible precursor chemicals comprising at least one reducible solid base metal chloride, a second stream comprising a control powder and a third stream comprising a Al reducing agent in a fine solid particulate form, at temperatures between T0 and Tmax to form a product in a powder form and a by-product including gaseous aluminium chloride; To is preferably below the melting point of the Al reducing agent and Tmax is between 400° C. and 1100° C.; reactions between the reducible chloride(s) and the Al reducing agent are exothermic and the method includes means for controlling the reaction rate and limiting the temperature of the reactants to less than the 1100° C. and more preferably to less than 1000° C. and still more preferably to less than 900° C. The reducible mixture may comprise precursor chemicals for alloying additives including metallic, semi-metallic or non-metallic elements from the periodic table.
Tmax depends on the physical characteristics of the base metal products and is generally limited by its melting temperature. Tmax is between 400° C. and 1100° C. and is preferably higher than the sublimation/evaporation temperatures of the starting base metal chlorides but preferably lower than the melting temperature of the base metal or alloy product.
In one embodiment, Tmax is below 1100° C. In a second embodiment, Tmax is below 1000° C. In a third embodiment, Tmax is below 900° C. In a fourth embodiment, Tmax is below 800° C. In a fifth embodiment, Tmax is below 700° C. In a sixth embodiment, Tmax is below 600° C.
The starting amount of the Al reducing agent depends on the amount of the starting reducible chemicals and the required concentration of Al in the end products. Preferably, the amount of Al in the starting materials relative to the reducible chemicals corresponds to a value between 80% and 5000% of the amount required to reduce all the reducible precursor chemicals to their elemental base metal state. The amount of Al in the base metal alloy product ranges from 0.0001 weight (wt) % to 90 wt %.
The choice of the control powder depends on the required characteristics of the alloy powder products. For common alloys and compounds, the control powder can be a pre-processed product or a semi-processed product of the reaction that is preferably mixed and reacted with the starting solid reducible precursors prior to reacting with the Al alloy. Also, the control powder can be one constituent of the required base metal or alloy product.
Preferably, base metal species in the control powder have a Cl content less than 50% and preferably less than 75% of the starting reactants. For production of composite products or multi-component products, the control powder can be one of the product constituents and may be different from the base metal species being processed.
The relative amount of the starting solid base metal chlorides to the control powder depends on a combination of factors, including the Gibbs free energy of the reaction between the base metal chloride and the Al, and thermal properties of the reactants and the control powder, and typically ranges from 0.03:1 to 50:1 or 100:1 by weight; for some highly exothermic reactions the ratio can be 1 part chlorides to 35 parts control powder by weight.
The present approach allows for low-cost production of a wide range of existing common alloys and compositions in addition to other compositions that may not otherwise have been possible to produce in commercial quantities. An advantage for the present approach in its preferred forms over prior relevant arts is in the ability to achieve effective control over reaction mechanisms and to maximise reaction yield for reducing the starting precursor materials.
Features of preferred forms of the present approach include:
The overall reaction between base metal chlorides and Al is:
MbClx+x/3Al=Mb+x/3AlCl3(g)+ΔG, ΔG<0 (R1)
Mb is the base metals and Mb Clx the corresponding reducible base metal chlorides, AlCl3(g) is gaseous aluminium chloride and ΔG is the Gibbs free energy for reaction (R1). Mb can be in the form of a pure element such as Ta, a solid solution such as Ni—Cu, a compound such as Ni3Al or a multi-component system such as metal matrix composites.
The ability of Al to reduce metal chlorides (and halides and oxides more generally) is well known and aluminothermic reduction of oxides and halides has been known for more than 100 years. Al is known to be a universal reactant and its ability to reduce metal halides is usually cited as an example for single replacement reactions commonly found in undergraduate text books and in basic chemistry essays, (e.g. see “Aluminium Alloys—New Trends in Fabrication and Applications”, Ed. Z Ahmad, InTech, 2012, DOI: 10.5772/52026; and Jena and Brocchi in Min. Proc. Ext. Met. Review vol 16, pp 211-37 1996). Examples for early attempts for production of metallic alloys through reduction of wide range of metal chlorides with Al can be found in U.S. Pat. Nos. 3,252,823 and 5,460,642. Other relevant literature involving Al can also be found in many early disclosures relating to reduction of metal chlorides and production of metal alloys (e.g. U.S. Pat. Nos. 1,373,038, 2,791,499 and 2,986,462 and 3,801,307, 4,604,62 and 4,191,557).
Aluminothermic reduction of transition metal compounds has been an active area of R&D since early last century. The main difficulties for aluminothermic reduction of transition metal chlorides are due to two factors; (i) the tendency of Al to alloy readily with other metals and (ii) the exothermic reactions between most transition metal chlorides and Al which often lead to uncontrollable processing with formation of arbitrary aluminide phases. Resolving these difficulties depends on the individual chemistry on the metals and from the perspective of aluminothermic reduction of metal chlorides, transition metals can be classified into three categories:
Preferably, the control powder is made of final or intermediate reaction products based on the base metals. Preferably, the pre-processed powders or alloys have a lower Cl content than the starting base metal chloride. Preferably, mixing of the base metal chloride powder and control powder with the Al reducing agent powder is carried out in a controllable way to enhance reactivity between the reactants and achieve external control over reaction rates and the resulting exothermic heat. Under all conditions, the reactivity of the control powder with the base metal chlorides or the Al is lower than reactivity between base metal chlorides and Al.
Further example aspects of the invention will be apparent from the description below and the drawings, and from the claims.
Features and advantages of the present invention will become apparent from the following description of embodiments thereof, by way of example only, with reference to the accompanying drawings, in which:
Table 1 presents a list of preferred base metals (Column 1) together with the corresponding melting and boiling temperatures (Column 2 and Column 3, respectively), the preferred starting chemical (Column 4) and the corresponding Gibbs free energy (ΔG) (Column 5) for reacting 1 mole of base metal chloride with Al at 400° C. according to (R1), the magnitude of temperature increases (Column 6) due to AG, the assumed control powder (Column 7) and the amount of control powder per 1 kg of starting base metal chloride (Column 8) required to limit the temperature rise to 200° C.
It can be seen in Table 1 that for all preferred starting chlorides, ΔG is negative, indicating that their reaction with Al per (R1) is exothermic and can result in excessive increases in the temperature of the products and the surrounding reactants as per the results in Column 6 showing the approximate increases in the temperature, ΔT, due to exothermic energy release. ΔT has been estimated by solving the equation:
where, Tr is the threshold reaction temperature, Cp-b is the specific heat of the base metal, Mb is the mass of the product Mb per mole of starting base metal chloride MbClx, and MAlCl3 and Cp-AlCl3 are respectively the mass and specific heat of the resulting aluminium chloride by-product per mole of MbClx. For the results in Table 1, it is assumed that exothermic energy release occurs in one step according to reaction R1 and the resulting heat is entirely absorbed by the resulting products (Mb) and by-product AlCl3. Therefore, the calculations represent an extreme case wherein the control powder acts only as a thermal absorber. For multi-valence base metal chlorides and for multi-component products, the effects of dividing the reaction into two steps due to chemical reactions between the control powder and the chlorides can dominate and then thermal load associated with the process reduces.
The calculated temperature increases in Table 1 are compared in
The data in Table 1 shows that heat generated by the reaction of the precursor chlorides with Al can melt the Al reducing agent. If this occurs, it would cause formation of large particles of arbitrary aluminide phases, and slow down or stifle further reduction of the starting chemicals. Thus, there would be formation of alloys with a high content of aluminium and with a non-uniform composition. Therefore, it is also an objective of preferred forms of the present invention to provide mechanisms for controlling the amount of Al in the end-product and enables production of alloys with controllable Al content down to less than 10 wt % and preferably down to 0% Al.
The mass of the control powder (base metal powder for the results in Table 1) required per 1 kg of base metal chlorides is determined based on requirements for limiting temperature increases of the resulting products below a certain predetermined value. Table 1, Column 8 lists the maximum amount of base metal powder required to limit increases in the temperature of the reaction product to less than 200° C. above the externally set temperature for reactions involving the base metal chlorides in Column 4. For the results in Table 1, the reactants and the control powder are all assumed to be heated externally to the threshold reaction temperature—assumed to be 400° C. The results in Column 8 have been obtained by solving equation 2 for Mc (mass of control powder):
with ΔT=200° C.
The data in Table 1, Column 8, is plotted in
According to some embodiments in the present disclosure, reactants at room temperature (25° C.) are gradually fed into a reaction zone containing the control powder at the reaction temperature. Therefore, the reactants would absorb energy to reach the reactant temperature and can contribute to limiting temperature increases due to exothermic energy generation.
Also, there exist other heat losses such as conduction through the reactor wall and heating/sublimation of diluents introduced with the reactants (e.g. AlCl3). In some embodiments of the method, aluminium chloride is introduced with the reactants and with the control powder, and it then can play an important role in cooling reactants in the reaction zone and help control the temperature. Under most practical conditions, it would be expected that the amount of control powder required would be less than 50% of the amounts in Table 1. As stated before, the addition of control powder reduces the reaction rate between the reducible MbClx and the reducing Al, allowing for a more effective external cooling and for higher heat losses due to conduction and convection. Also, the amount of control powder required reduces with increases in the allowed temperature range, and if the acceptable maximum temperature 400° C. above the threshold reaction temperature, then the amounts of required control powder in Table 1 would be reduced by 50%.
It follows from the previous discussion that the reactants must still be externally cooled at a rate equivalent to heat generated by the reactants, but following the procedures described here allows for the cooling and overall heat management of the process to occur under mild conditions with only moderate increases in the reactant and vessel temperatures.
The inventor estimates that when the weight ratio of the control powder to the reducible base metal chlorides is equal to one, the reaction rate between the reducible precursors and Al reduces by a factor of 4, thus extending the reaction over longer periods and allowing for more effective energy management; as a result, there would be need for lower amounts of control powder.
Other factors that can affect the required amount of control powder include the threshold temperature of the reaction (Tr), the base metal characteristics, and the specific heat and total enthalpy of the base metal and the base metal chlorides. The control powder can be a mixture of different materials, but reactions between the control powder and the other reactants should not increase the thermal load resulting from the reacting system.
Accurate determination of the required amount of control mass requires analysis of all relevant processing conditions, accounting for the physical properties of the reaction vessel and for heat losses and cooling mechanisms available in the reaction zone. Estimates in Table 1 are provided only as guidance and variation in the listed numbers relative to specific experimental conditions would be apparent to a skilled addressee.
The inventor estimates that under practical conditions and with proper control over reactant flows and mixing, the amounts of control powder listed in Table 1 can be further reduced at least by a factor of between 2 and 5. In all embodiments, the amount of control powder should be between Mc/100 and Mc where Mc is defined by equation (2).
The control powder can be added in several ways depending on the reactor configuration. In one embodiment, the control agent is mixed with the starting base metal chlorides before reacting with the Al reducing agent. In another embodiment, the control agent is mixed with the Al reducing agent before reacting with the starting base metal chlorides. In a third embodiment, the control agent, the reducible base metal chlorides and the Al reducing agent are fed separately into the reaction zone where they get mixed and reacted. The choice of a suitable arrangement depends on the relative reactivity between the control agent and the reducible chlorides and the reducing Al. In a preferred embodiment, the control powder is a fully processed product or a semi-processed product of the reaction between the base metal chlorides and the Al alloy. In another preferred embodiment, the control powder is the base metal alloy product and is produced in-situ.
The inventor finds that if no control agent is added, the hot by-products generated by the reaction can cause significant increases in the pressure with rapid gas movements, that may blow the reactants out of the reaction zone. If the control powder had a lower reactivity with the reactants and if it existed in quantities larger than the reactants, then the reactants would be distributed into localised small sites within the control powder matrix wherein each site is surrounded by control powder. When the reaction occurs, gaseous by-products accelerated out of the localised reaction sites collide with the surrounding control powder, transferring their kinetic energy to the powder and causing significant mixing throughout the reactants body. The inventor found that even with a very limited mixing between the reducible chlorides and the reducing Al powder, the reaction efficiency is significantly enhanced by self-mixing generated by the by-product gas micro-flows. As discussed below, for most of the base metals and base metal chlorides subject of the present invention, temperature increases in the reaction products generated by the exothermic energy release exceeds 200° C. above the threshold reaction temperature Tr. Thus, the resulting local pressure at the localised reaction sites is more than 1.01 atm and is likely to be more than 1.1. This would generate fast localised gas flows (short bursts) within the reactant body with velocities up to more than a hundred meters per second, inducing significant mixing within the reactant body and playing a key role in transferring exothermic energy released by the reaction away from the local reaction sites and the immediate surrounding control powder.
The inventor found that for a pure Al powder (with an average particle radius R), and with a ratio [MbClx]/[Al]=a and a ratio [Mc]/[MbClx]=b, and with a reactant packing density D (reactants are Mc, MbClx and Al), local increases in pressure due to fast reactions between the base metal chlorides and Al can be expressed as
where N is Avogadro's number, NAr is the number density of Ar at the reaction temperature and ΔNAl is the amount (number of atoms per cm3) of Al that reacted. The inventor found that even for one per thousand of the available Al reacting (ΔNAl/NAl=0.001), the resulting increases in the localised pressure can be up to 0.25 atm. For ΔNAlNAl=1%, ΔP can be up to 2.5 atm with the localised pressure reaching 3.5 atm.
The weight ratio of the solid base metal chlorides to the control powder may be determined based on tolerable increases in the temperature of the products that can result from the exothermic energy release. It is preferable that heat generated by the exothermic reaction does not increase the temperature of the products in the reaction zone higher than the melting point of the base metal. It is preferable that that heat generated by the exothermic reaction does not increase the temperature of the products in the reaction zone higher than the melting point the Al reducing agent.
In one embodiment, temperature increases resulting from exothermic heat generated by the reaction of the base metal chlorides and the Al is limited to less than 600° C.
In another embodiment, temperature increases resulting from exothermic heat generated by the reaction of the base metal chlorides and the Al is limited to less than 400° C.
In a third embodiment, temperature increases resulting from exothermic heat generated by the reaction of the base metal chlorides and the Al is limited to less than 200° C.
In a preferred embodiment, the present invention provides a method for production of base metal alloys in a powder form, comprising the steps of:
The maximum set temperature in the Reduction Stage, T1, is determined by factors including the kinetics barrier of reactions between the precursor material and the Al reducing agent and the characteristics of the reactants such as the purity and particle size of the Al alloy powder. Preferably, T1 is below the melting temperature of Al and more preferably below 600° C. By way of an illustrative example only, if nickel was the base metal and NiCl2 was the reducible base metal chloride, then the Stage1 maximum set temperature would be below 500° C.
The maximum set temperature in the Purification Stage, Tmax, is determined by factors including the morphology and composition of the end-product in addition to the requirement of evaporating any residual un-reacted chemicals remaining within the solid products. Preferably, Tmax is set at a temperature slightly above the highest sublimation/evaporation temperature of the base metal chlorides being processed. If nickel was the base metal and NiCl2 was the reducible base metal chloride, then Tmax is below 900° C.
In one preferred embodiment, the Al reducing agent is pure Al. In another embodiment, the Al reducing agent is pure Al alloyed with other elements. The Al reducing agent is preferably a powder or flakes in a fine particulate form.
In one preferred embodiment, aluminium chloride is mixed with Al to form an Al—AlCl3 mixture corresponding to between 10 wt % and 500 wt % of the weight of the base metal chlorides. Including AlCl3 helps dilute and spread the Al more uniformly when the Al—AlCl3 is mixed with the base metal chloride and increase the contact surface area with the chloride and thus increase reaction efficiency. Also, the AlCl3 can act as a coolant to the reactants in the Reduction Stage.
In one embodiment, by-products from the Reduction Stage together with any base metal compounds escaping with the gaseous by-products are collected and returned for processing in the Reduction Stage. In one variation of this embodiment, the recycling process is carried out continuously. In another variation, the collected materials are mixed with products obtained at the end of the Reduction Stage and then the resulting mixture is reprocessed though the Reduction Stage as described before. In still another variation, a part of the intermediate products from the Reduction Stage are used as a control powder. In one form of this variation, the intermediate products include AlCl3.
In all preferred embodiments, the reducible solid precursor is a metal halide (preferably chloride) or a mixture of metal halides of the base metals. Examples of preferred starting chlorides include ZnCl2, VCl(2,3), CrCl(2,3), COCl2, SnCl2, AgCl, TaCl(4,5), NiCl2, FeCl(2,3), NbCl5, CuCl(1,2), PtCl(4,3,2), WCl(4,5,6), PdCl2 and MoCl5 respectively corresponding to base metals of Zn, V, Cr, Co, Sn, Ag, Ta, Ni, Fe, Nb Cu, Pt, W, Pd, and Mo. The solid base metal chlorides are preferably in the form of a finely divided particulate powder and their reduction is carried out through reactions with a control powder based on Zn, V, Cr, Co, Sn, Ag, Ta, Ni, Fe, Nb Cu, Pt, W, Pd, and Mo in a fine particulate form and a solid Al alloy also in a fine particulate form. In a preferred embodiment, the solid base metal chlorides have an average grain size less than 100 microns and preferably they are in the form of a powder or flakes in a fine particulate form.
In one embodiment, the base metal chlorides are mixed/milled to homogenise the compositions.
In one embodiment, the base metal chlorides are mixed with an AlCl3. The mixing can be carried out by co-milling.
In one embodiment, the base metal chlorides are mixed with an AlCl3 to produce at least one eutectic phase based on base metal chloride-AlCl3. The mixing can be carried out by co-milling.
In one embodiment, the base metal chlorides are mixed with an AlCl3 to increase dilution of the base metal chlorides within the reactant matrix. The mixing can be carried out by co-milling.
Alloying additives can be included through precursor chemicals in the reactant streams or through a separate additional stream if necessary depending on compatibility with the solid base metal chlorides and the Al reducing agent. The alloying additives may be a compound or a mixture of compounds or elements based on one or more elements from the periodic table such as O, N, S, P, C, B, Si, Mn, Al, Ti, Zr and Hf. Addition of the alloying additives can be done through various means and at various points during the process during the Reduction Stage or the Purification Stage. Preferably, the additive precursors are in the form of halides.
Alloying additives that do not meet the exothermicity criterion can present difficulties and may require special procedures to be incorporated properly. For example, additives such as Ti, Mn and Zr can act as reducing agents for the base metal chlorides, degrading the end-product and causing retention of excessive levels of Al together with impurities of Ti chloride, Mn chloride and Zr chloride. Alloying additives based Ti, Mn and Zr may be included only if Al can be tolerated as a part of the end-product composition, and then particular care needs to be taken to prevent formation of segregated aluminide phases, accommodate for losses of TiClx, MnClx and ZrClx and minimise presence of unreacted chlorides in the end-product.
In one embodiment of the method for producing alloy compositions including additives Ti, Mn, Zr and Al, chlorides of Ti, Mn and Zr are first reacted partially or fully with a reducing agent and then the resulting products are thoroughly mixed and processed with the other reactants at temperatures above 700° C.
In one embodiment, the Reduction Stage is operated in a batch mode. In another embodiment, the Reduction Stage is operated in a continuous or a semi continuous mode.
In one embodiment where the Reduction Stage is operated in a batch mode, in continuous mode or in semi-continuous mode, intermediate products from the Reduction Stage are used as a control powder. In one form of this embodiment, the control powder is produced in-situ. In yet another form, end-products are used as a control powder.
In one embodiment, intermediate products from the Reduction Stage are not transferred into the Purification Stage until the Reduction Stage operation is concluded. In another embodiment, intermediate products from the Reduction Stage are continuously transferred into the Purification Stage.
In one embodiment for production of alloy powder with an Al content higher than 15 wt %, the Reduction Stage is preferably operated in a mode wherein the Al reducing agent is fed at a rate corresponding to that required for reducing the base metal chlorides to their pure elemental base metals with no excess Al, and then after the total amount of the base metal chlorides have been dispensed, the remaining Al alloy powder is fed at a rate so that the resulting temperature of the Reduction Stage reactants is less than 660° C.
In one embodiment, wherein the starting precursor materials have a low boiling/sublimation temperature lower than the Reduction Stage reaction temperature, the method comprises an internal recycling step in the Reduction Stage, where the Reduction Stage reactor is arranged in use to condense and collect reactants emanating from the reaction zone and return them for recycling. In one form of this embodiment, materials condensed and returned to the reaction zone can include aluminium chloride. The Reduction Stage products are then processed through the Purification Stage according to any of the foregoing or forthcoming aspects and embodiments.
In one embodiment, the Purification Stage is operated in a batch mode. In one embodiment, the Purification Stage is operated in a continuous mode.
In one embodiment, the ratio of Alto the reducible chemicals is lower than the stoichiometric ratio, and thus there would be an excess of reducible chemicals in the starting materials. The excess reducible chemicals are evaporated during the Purification Stage processing, and then they are collected and recycled.
In one embodiment, unreacted precursor materials processed through the Purification Stage at temperatures up to Tmax are evaporated and condensed in regions at lower temperatures, and then continuously recycled through either through the reduction Stage or the Purification Stage as described before. In one for form of this embodiment, the recycling is done in a continuous form.
In all preferred embodiment, the reactants are not mixed beforehand as there can be intrinsic reactions leading to generation of a large amount of heat with possible pressure build-up due to overheating of gaseous aluminium chloride by-products generated by the reaction.
In any of the embodiments, the method can comprise a pre-processing step for forming solid metallic subchlorides to be used as starting precursor materials.
When the starting chloride is a liquid or a gas, then the method can comprise a primary step for reducing the primary chloride to produce a lower valence chloride. For example, when Sn is the base metal and SnCl4 is the preferred starting chemical, the method includes the primary step of reducing SnCl4 to SnCl2. This can be carried out using various routes, including reduction with alkali metals and reduction with hydrogen at high temperature.
Preferably, this primary reduction step is carried out using reduction with Al according to
MbClx(l,g)+(x-z)/3Al→MbClz(s)+(x-z)/3AlCl3 (R4)
and then the resulting solid MbClz(s) which may include residual Al is used as a solid precursor materials as described above. MbClx(l,g) is the liquid/gas chloride and MbCz (s) is the solid chloride.
In one preferred embodiment, the primary starting chloride has a boiling/sublimation temperature comparable to or lower than the threshold reaction temperature in the Reduction Stage, and then the method can comprise a pre-processing step for forming solid metallic subchlorides to be used as starting precursor materials. In one form of this embodiment to produce alloys based on Fe, Ta, Mo, Nb, W, and V, the starting precursor materials including FeCl3, TaCl(4 or 5), MoCl5, NbCl5, WCl(4,6), and VCl(3,4) are first reduced to produce a mixture including subchlorides (i.e. FeCl2, TaCl(2,3,4)), MOCl(2,3), NbCl(2,3), WCl(2,3,4), and VCl(2,3)) per any available art including any of the foregoing and forthcoming embodiments and then the resulting mixture is reduced to the base metal or base metal alloy per any of the foregoing and forthcoming embodiments.
In a preferred embodiment, the method comprises the step of continuously driving gaseous by-products away from the reaction zone by flowing gas in a direction away from the solid reactants and the end products. In one form, the gas can be inert gas (e.g. Ar or He). In other forms, the gas may include reactive components that can partly or fully react with the precursor materials or the solid reactants (e.g. O2 and N2).
In one embodiment, the powder product is based on carbides, silicides, borides, oxides, or nitrides of Zn, V, Cr, Co, Sn, Ag, Ta, Ni, Fe, Nb Cu, Pt, W, Pd, and Mo. The powder product is produced by processing metal chlorides with alloying additives including C, Si, B, O2 or N2 according to any of the foregoing and forthcoming embodiments.
In a preferred embodiment, aluminium chloride by-products condensed in parts of the reactor at lower temperature and collected separately.
In any of the embodiments, the method can be carried out at pressures between 0.0001 atm and 2 atm.
In all embodiments, the product is a powder composed of a base metal alloy or compound and can include any number of alloying additives based on any number of non-inert elements from the periodic table.
In all forms and embodiments of the method, the end-product of said method can include aluminium residues.
In all embodiments, the method can comprise the step of separating the end products from any residual unreacted precursor materials and unreacted aluminium. The method can also include the step of washing and drying the end products.
In one embodiment, the aluminium chloride by-products are reacted with base metal oxides at a temperature TCl-O to produce base metal chlorides and aluminium oxide:
MbOx and AlCl3→MbCly and Al2O3 (Ro1)
where MbOx is the base metal oxide and MbCly is the base metal chloride. MbCly is then separated from the rest of the reaction products and recycled as a starting base metal chloride according to any of the embodiments and aspects described herein.
TCl-O depends on the base metal oxide and can range from room temperature to more than 800° C. In one form of the embodiment, TCl-O is below 200° C. In another form, TCl-O is above 200° C. In another form, TCl-O is above 500° C. In another form, TCl-O is above 800° C.
In one embodiment, reaction Ro1 is carried out under inert atmosphere. In another embodiment, Ro1 is carried out in the presence of a Cl gas or HCl.
In a first step, a control powder (1) is mixed and reacted with base metal chlorides (2) in (3). The resulting mixture is then reacted with Al (4) in step (5). Steps (3) and (5) together form the Reduction Stage (6). A part of the resulting product is recycled (7) through (1) and the remainder are moved for purification in (8). The products are discharged in (9). A part of the end-product may optionally be recycled (10) as control powder through (1). By-products (11) from the Purification Stage (8) can—optionally—be reacted with base metal oxides in (12) to produce base metal chlorides (13) which can then be recycled (14) through (2). The final by-product from step (12) would then be aluminium oxide (15).
In a first step (1), an Al reducing agent is mixed with AlCl3 to help dilute the Al and produce a more homogenous distribution during processing. Other alloying additives may be added and mixed with the Al—AlCl3 if required. The control powder (2) and the base metal chlorides (3) are mixed, preferably continuously, in a premixer (4) under inert gas and under controlled conditions, together with other compatible alloying additives leading to Stream 1 (5). The Al reducing agent is mixed (6-7) with other precursors as appropriate (8) to form Stream 2 (9). The remaining alloying additive precursors (10) are prepared into one or more additional Stream 3 to n (11). Stream 1 (5), Stream 2 (9) and Stream 3-n (11) are reacted gradually in the Reduction Stage at temperatures between 160° C. and 600° C. (12). The Reduction Stage may include an internal recycling step (12A) wherein materials (12B) escaping the Reduction Stage reaction zone (12A) are condensed and recycled. Materials at the exit of the Reduction Stage may be recycled (12C) through (2) to be used as control powder. By-products (13) resulting from the Reduction Stage, including aluminium chlorides, may optionally be removed away from the reaction zone. However, in a preferred embodiment, by-products are recycled through (12A) or (12C). The Reduction Stage may be operated in a batch mode or in a continuous mode.
At the end of the Reduction Stage processing, materials are then processed through the Purification Stage (14) at temperatures between 200° C. and 1000° C. to complete the reaction and evaporate/remove residual un-reacted chemicals (15). The un-reacted chemicals (15) may be recycled (16) through the Reduction Stage or through the Purification Stage. By-products from the Purification Stage (13) are continuously removed away from the solid reactants. At the end of the high temperature processing cycle, the products are discharged (17) for post processing or storage (18). A part of products (17) may be recycled through (17A) to be used as control powder (2). All processing steps including mixing, and preparation of the precursor materials are preferably carried out under an inert atmosphere and any residual gas at the exit of the processing cycle is processed through a scrubber (19) to remove any residual waste (20). In one embodiment, remaining aluminium chloride by-products (21) are reacted with base metal oxides (22) to produce reaction products including base metal chloride and aluminium oxide. The resulting products are then processed in (23) to separate the base metal chlorides (24) from other by-products of the chlorination reaction (Ro1) (24). The resulting base metal chlorides (24) can then be withdrawn (25) or recycled through (3).
In one embodiment of the method in a continuous mode, wherein chlorides with a low boiling/sublimation temperature such as TaCl5, NbCl5, MoCl5, WCl4, FeCl3, VCl4 and SnCl4 are used, materials evaporated from the Reduction Stage reactor are condensed separately or together with other reaction by-products such as aluminium chlorides outside the reactor in a dedicated vessel and then fed back into the reactor during the same processing cycle through one of the reactor inlets. The feeding rate of the condensates is regulated to avoid overloading of the reactor. In a second embodiment of the method, the collected condensates are recycled through the Reduction Stage, and this recycling process can be carried out multiple times or until all the starting base metal chlorides have been reduced. In this embodiment, the recycling can occur several times or continuously to minimise the concentration of the base metal chlorides in the collected aluminium chloride by-products. In one variation of this embodiment, the condensates are used as a control powder.
Here, a condenser linked to the Reduction Stage can be used and the temperature in the Reduction Stage reactor is set at a temperature below 600° C. while the temperature of the condenser is set a temperature below 200° C. Materials evaporated from the reactor are condensed in the condenser zone either as pure molten TaCl5 or as a mixture or a solution TaCl5—AlCl3 and then the condensed materials are driven back the reaction zone. This recycling process provides a cooling mechanism for materials in the reactor due to evaporation-condensation-recycling and provides a self-regulating mechanism for keeping the pressure in the reaction vessel close to 1 atmosphere.
In one embodiment, the alloy product is a superalloy based on nickel, cobalt or iron.
In one embodiment, the alloy product is a high entropy alloy (HEA), including at least four elements from the group including the base metals, Al and the alloying additives, with individual concentrations ranging from 5 wt % and 50 wt %. In one form of this embodiment, the constituent elements are equimolar. The HEA powder must include at least two base metals.
In one embodiment, the method includes the additional step of post-processing the powder to make its grains substantially spherical, for example by plasma processing, to make the grains suitable for use in 3D printing.
In one embodiment, the alloy product is a magnetic powder based on Fe, Ni and/or Co. In one form of this embodiment the product is an Alnico powder based on Fe—Al—Ni—Co and produced according to any of the foregoing or following embodiments of the method and then there are the additional steps of consolidating the resulting alloy powder, shaping the resulting consolidated article, and then magnetising the shaped article to produce a magnet. The powder produced according to this embodiment can include alloying additives and Al.
In one embodiment of the method for production of catalysts, a base metal powder is produced according to any of the embodiments of the method, the powder is based on Al, Zn, V, Cr, Co, Sn, Ag, Ta, Ni, Fe, Nb Cu, Pt, W, Pd, and Mo, and optionally including alloying additives, and then there can be the additional optional step of further processing the resulting base metal alloy powder to produce a catalyst. In one form of this embodiment, the powder product has an Al content of more than 10 wt %, and there is the additional step of dissolving the Al by an operable means to produce a skeletal catalyst. Operable means include washing the powder product with alkaline solutions (e.g NaOH) or acidic solutions (H2SO4, HF . . . ).
In one variation of the last embodiment, a powder with a composition of MbxAlyCz is produced in accordance with any of the foregoing or following embodiments and then the Al is removed by washing the powder product with alkaline solutions (e.g NaOH) or acidic solutions (H2SO4, HF . . . ) to obtain a composition MbxCz with tailored pore structure and tailored morphology; x, y and z represent the molar number for Mb, Al and C. The resulting material structure can be a layered structure or porous structure or nanostructured structure with an MbxCz based composition.
In one embodiment, the method includes the optional additional step of exposing the powder product to a reactive substance to form a coating on the powder particles.
Generally, the product of the method is in the form of a powder with a spongy structure and with a grain size between 5 nm and 500 microns.
In one preferred embodiment per the fourth aspect, there is provided a method for production of a multi-component powder or a composite powder, wherein the control powder has a substantially different composition from the elemental composition produced through reduction of the starting base metal chlorides with Al and wherein the final product contains a substantial amount of unreacted control powder; the control powder can be one or a mixture of flakes, fine or coarse particulate and fibrous materials. In one form of this embodiment, the control powder consists of a pure metal or an alloy with a composition different to the elemental composition produced by reducing the starting base metal chloride with Al. Carrying out the process per any of the previous embodiments causes the control powder to be covered or surrounded by alloys or compounds resulting from the reduction of the starting chemicals with Al. The control powder can be made of particles in the form of one or a mixture of spherical particulates, irregular shape particulates, flakes, or fibres.
Referring to the diagrams in
In all embodiments, inert gas may be used to help direct gaseous chloride species through the various processing zones or outside for collection and further processing and/or recycling. In all embodiments, unreacted base metal chlorides may be condensed and returned for processing at higher temperatures in the reactor either continuously or in a batch mode.
The residence time of the reactants through the Reduction Stage at temperatures below T1 is determined by a combination of factors including the threshold reaction temperature and the physical characteristics of the base metal chlorides being processed; preferably and where possible, T1 is set at a value below the boiling/sublimation temperature of the starting base metal chlorides.
As materials from the Reduction Stage progress through the Purification Stage reactor, remaining un-reacted materials react, leading to formation of Al chloride by-products. An external gas flow can be used to help drive volatiles from the reactants in a direction opposite to the movement of the solid reactants. The external gas flow drives the AlCl3 by products away from the solid products and out of the reactor where they are stripped out of the gas stream in a dedicated collector at a temperature lower than 160° C. Reactants in the Purification Stage reactor are preferably continuously mixed to help maximise reaction yield and minimise losses of base metal chlorides. Un-reacted materials reaching the high temperature section within the Purification Stage reactor are evaporated and driven by the external gas flow towards lower temperature regions where they are condensed and then recycled.
The residence time of the materials through the Purification Stage of the reactor affects the degree of agglomeration/sintering of the powder products and the method can include the step of varying the residence time to obtain a desired particle size distribution/morphology.
As discussed before, the processing temperatures in both the Reduction Stage and in the Purification Stage, are determined by the materials properties of the base metals and the base metal chlorides, in addition to the composition and morphology of the end-product. The value of the minimum temperature can also depend on the sublimation temperature of precursor materials and the method can include a primary reduction step as described in following embodiments. However, it is preferable that the minimum temperature in the Purification Stage reactor be around 200° C. so that it is higher than the sublimation temperature of aluminium chloride.
Another objective of the present invention is to provide a reactor for carrying out the method as described in the various embodiments. The reactor consists of vessels for carrying out the Reduction Stage and the Purification Stage reactions and may be made of any materials capable of withstanding temperatures up to 1100° C. without reacting with the precursor chemicals and end-products. The reactor might consist of any containment vessel and associated accessories capable of providing intimate and efficient contact between the reducible materials stream and the reducing Al alloy stream. The reactor can consist of two separate vessels for the Reduction Stage and the Purification Stage or of a single vessel arranged in use to handle both the Reduction Stage and the Purification Stage reactions. Both the Reduction Stage reactor and the Purification Stage reactor can include mechanisms for moving and mixing the reactants. In a preferred embodiment, the Purification Stage reactor consists of a tubular reactor capable of operating at temperatures up to 1100° C., with means for moving, mixing, heating, recycling and transferring the reactants, a by-product collection unit and an end-product collection unit.
In a preferred embodiment, the reaction vessel may comprise several discrete heating zones, each zone providing for a different reaction or condensation function.
In all embodiments, the reactor can further comprise further gas inlets located throughout the reaction vessel and its accessories.
In all embodiments, the reactor comprises exhausts for removing gases from the reactor.
In one embodiment, the reactor can comprise moving apparatus for moving and mixing the powder from the reactor inlet to the reactor outlet.
For this basic configuration, there is provided a mixer/reactor system intended for illustrating key functions of a reactor suitable for implementing some preferred continuous embodiments. The Reduction Stage reactor main body (301) is a cylindrical vessel made of materials capable of handling chemicals based on the base metals and the alloying additives at temperatures up to 1100° C. The reactor vessel (301) includes means for heating and cooling the vessel at the required operating temperatures. A continuous premixer (302) is provided with a mixer (303) driven externally by (304) for mixing base metal chlorides (305), the control powder (306) and the reducing Al alloy powder (307), and then the resulting mixture is fed through inlet (309) to the reactor (301). Also, provided but not shown in the diagram are hoppers and feeders for holding and transporting the reactants into the premixer. The premixer is not critical to the operation of the reactor and feeding inlets may or may not be directly attached to the reactor body. Gas inlet (310 and 310A) are also provided at the inlet of the reactor and a flow is imposed through (301) in the same direction as the solid reactants. Alloying additives may be introduced either directly to the premixer (302) or as a component of the other reactants (305) and (307).
At the exit of reactor vessel (301), there is provided a condenser (311) wherein materials from (301) including gaseous species escaping/evaporated from the reactor vessel (301) can be made to condense/cooled down prior to transferring into a holding vessel (312). The condenser is held at room temperature and includes means for transporting the reactants from inlet to exit. Means for condensing gaseous species in the condenser can include any prior known arts including fluidised bed, cooled scrappers and/or any other means that can condense gaseous chloride species and mix with other solid product to produce mixture (314) prior to transfer into (313). The temperature of the condenser is regulated using external cooling means (not shown). Inert gas from (301) can exit through port (315). A part of mixture (314) is driven using an appropriate conveyor system (316) back to the premixer and used as a control powder. The remaining part is transferred into the Purification Stage reactor (317).
In one embodiment not shown here, the reactor vessel (301) includes an additional exhaust at the level of the powder exit and this additional exhaust can be used to remove gaseous aluminium chloride prior to the reactant fed into condenser (311).
For the Purification Stage, there is provided a basic conveyor screw configuration intended only for illustrating key functions of a reactor suitable for implementing some preferred embodiments as per foregoing aspects of the invention described herein. The purification reactor main body consists of a tubular main section (317) made of materials capable of operating at temperature up to 1100° C. and not react with the materials processed therein. For the example in
On the product outlet end, there is provided one or multiple openings (322) to introduce inert gas and gaseous precursor materials. Also provided is a product outlet opening (323) and a product collection vessel (324).
Preferably, Section (317) and all internal walls located within this section are kept a temperature higher than the boiling temperature(s) or the sublimation temperature(s) of the by-products. Section (317) has a minimum temperature T2 at the entry of the powder through (321) increasing to a temperature Tmax at the level of (325) and then decreasing to room temperature at the level of powder product outlet. Temperatures T2 and Tmax depend on the materials being processed therein. T2 and Tmax are regulated using heating/cooling means (not shown). T2 is preferably higher than the sublimation temperature(s) of the by-products. Preferably, minimum temperature in T2 is around 200° C.
As discussed before, Tmax is preferably below 1100° C. and more preferably below 1000° C. and still more preferably below 900° C. Past the reactor section at Tmax, the products are progressed towards the powder exit where they are cooled to room temperature and discharged. By way of example, for conditions where nickel chlorides are being reduced with Al, maximum temperature for the Reduction Stage (301), T1, is set at 500° C., minimum temperature in the Purification Stage, T2, is preferably set to 200° C. and Tmax is set to a temperature between 850° C. and 950° C.
The configuration in
For the reactor configuration in
As products from the Reduction Stage progress though reactor section (317), remaining unreacted materials are reacted or evaporated. An external gas flow is driven into the reactor through the gas opening (322) in a direction opposite to the movement of the solid reactants. The external gas flow helps drive by-products out of the Purification Stage reactor. Reacting materials in section (317) are continuously mixed to maximise contact surface area between the reactants and enhance reduction reactions residual unreacted reactants. Product formation proceeds through formation of small particulates of sub-micron dimension first followed by sintering and agglomeration of the particulates leading to products with large particle size. The residence time of the materials through the reactor affects this agglomeration/sintering process and the method includes the step of setting the residence time to obtain a desired particle size distribution and degree of agglomeration.
In a preferred embodiment, the heating/cooling means in sections (301), (311) and (317) manage heat flow within the reactor and maintain the temperature profile required for processing through both stages but particularly through the Reduction Stage. As can be seen in Table 1, for all base metals subject to this disclosure, the reactions between the precursor base metal chlorides and the reducing Al alloy are highly exothermic. Nevertheless, some parts of the reactor body may need to be heated initially to reach a threshold temperature adequate for initiating the reaction, but then the reactor may need to be cooled to maintain the threshold temperature and prevents overheating.
The following examples illustrate preparation of base metal alloys and compounds in accordance with embodiments of the present invention.
Ms: Mass of starting chemicals (mg)
Me: Mass of base metal element in end-product (mg)
Control powder: Fe—Al—Cr alloy.
Total end products: ˜825 mg
The following method has been used for the tests in the examples listed below. Ecka Al powder with a grain size 4 microns is used for all tests except where stated otherwise.
Control powder: Ni. The Al powder is mixed with 1.740 g of AlCl3.
Total end products: ˜2 g
The reduction process is carried out as described before for Example 1. The resulting powder consisted of agglomerated irregular spongy grains with a wide size distribution. The powder was analysed using XRD, XRF and ICP. The XRD trace is in
Control powder: Fe. The Al powder is mixed with 1.940 g of AlCl3.
Total end products: ˜1.8 g
The reduction process is carried out as described before for example 1.
The powder was analysed using XRD, XRF and ICP. The XRD trace is in
Control powder: Semi processed intermediate products from Reduction Stage. The Al powder is mixed with 9.25 g of AlCl3.
Products: ˜9.6 g
The reduction process is carried out as described before for example 1. The powder consists of irregular agglomerated particles. The XRD trace is in
Control powder: semi-processed INCONEL-AlCl3 powder from the Reduction Stage. The Ecka Al powder is mixed with 4.434 g of AlCl3.
Products: ˜4.85 g
The reduction process is carried out as described before for example 1. The XRD trace is in
Control powder: semi processed MAR-M-509-AlCl3 from the Reduction Stage. C is introduced in the form of milled graphite, 1 part graphite-9 parts AlCl3. Al is introduced as Al—AlCl3 1 part Al-3 parts AlCl3. The Al powder is mixed with 4.265 g of AlCl3.
Products: ˜4.8 g
The reduction process is carried out as described before for example 1. The XRD trace is in
TaCl5+1.666 Al=Ta+1.666 AlCl3
Ecka Al (grain size=4 microns) is mixed with AlCl3 (wt ratio 1:2); total: 3.730 g.
The amount of TaCl5 is 5% above stoichiometric level to account for losses associated with the manual processing of the materials. Excess tantalum chlorides are removed during the Purification Stage.
Control powder: Ta.
Total end products: ˜4.77 g
The reduction process proceeds as follows:
Furnace is set at 500° C.
Step 1: 100 mg of TaCl5+33 mg Al—AlCl3 introduced into a quartz tube.
Step 2: Insert quartz tube into furnace; as the reaction occurs and aluminium chloride by-products+some TaCl5 evaporate and get deposited onto cold section of the tube.
Remove tube from furnace.
Scrape by-products+residuals back into reaction zone at the bottom of the tube.
The resulting mixture will be used as control powder for next reaction cycle.
Step 3: Add 50 mg more than step TaCl5 and third the weight of TaCl5 of Al—AlCl3.
Mix with control powder already in tube.
GO to Step 2.
Continue process until all TaCl5 is used.
Add remaining Al—AlCl3 and go to Step 2.
Mix products with collected by-products+residuals.
Heat at 500° C. for 10 minutes.
Collect by-products+residuals.
Mix products with collected by-products+residuals
Heat at 500° C. for 10 minutes. Collect and remove resulting by-products.
Heat in rotating quartz tube at temperature from 500° C. up to 1000° C. in steps of 100° C., for 10 min in each step.
Collect product. Wash and dry.
Analysis: XRD analysis for the resulting materials is shown in
Starting precursor for boron is B powder. Ecka Al (4 microns) is mixed with 1.555 g of AlCl3.
The process is carried out as described in Example 1. ˜0.92 g of powder collected. An XRD spectra is shown in
Control powder: AlCoCrCuFeNi HEA powder. Ecka Al (grain size=4 microns) is mixed with AlCl3 (wt ratio 1:2); total: 4.050 g.
Total end products: ˜3 g.
The reduction process is carried out in two steps:
First, procedures described for Example 1 are used throughout the Reduction Stage to obtain an approximate composition equivalent to CoCrCuFeNi.
Then, the remaining Al is added gradually using same procedure used Example 1.
The resulting materials are then processed through the Purification Stage to remove residual chlorides and coarsen the powder products.
XRD patterns for the resulting powder products is shown in
The products were analysed using XRF and ICP and the results conforms to the expected composition.
The base metal chlorides are mixed with 2.7 g of AlCl3
Ecka Al (4 microns) is mixed with AlCl3 (wt ratio 1:2); total: 2970 mg.
The reduction process is carried out in two steps:
First, procedures used for Example 1 for MAR-M-509 are used throughout the Reduction Stage to obtain an approximate composition equivalent to Co.
Then, the remaining Al is added gradually using same procedure used Example 1.
The resulting materials are then processed through the Purification Stage to remove residual chlorides and coarsen the powder products.
XRD patterns for the resulting powder products is shown in
A 1 g sample of the Co—Al powder is washed (for 2 hours) in 60 ml of H2O plus 10 ml of NaOH (50% mol). The powder is then rinsed in distilled water until PH is neutral. An XRD trace of the resulting materials is in
The present method may be used for production of alloys and compounds of various compositions including compounds of pure metal, oxides and nitrides of Al, Zn, V, Cr, Co, Sn, Ag, Ta, Ni, Fe, Nb Cu, Pt, W, Pd, and Mo and including alloying additives as described before. Modifications, variations, products and use of said products as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.
Materials produced using the present invention have unique characteristics that may not be obtained using prior arts. Our claims extend to materials that can be made using the present invention and use of the materials, without limitations by the examples provided in these specifications by way of illustration. Specific properties include the ability to produce nano-structured and/or complex compositions that can be unachievable with conventional powder production techniques.
In the claims, which follow and in the preceding description of embodiments, except where the context requires otherwise due to express language or necessary implication, the words “comprise” (and “include”) and variations such as “comprises” or “comprising” (and “includes” or “including”) are used in an inclusive sense, to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.
Also, it will be understood to persons skilled in the art of the invention that many modifications may be made without departing from the spirit and scope of the invention; in particular, it will be apparent that certain features of embodiments of the invention can be employed to form further embodiments.
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| WO2018/006133 | 1/11/2018 | WO | A |
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