Patent Application
20160024628
Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR 1.57.
1. Field
The disclosure generally relates to hardfacing materials which can be deposited as hardfacing coatings without the production of Cr, such as hexavalent Cr dust.
2. Description of the Related Art
Thermal spray processing is a technique which can be utilized to deposit a hard wear resistant and/or corrosion resistant layer onto the surface of a component. Thermal spray inherently creates a significant amount of dust due to the fact that about 10-40% or more of the feedstock material does not stick to the component of interest and rebounds of the surface in the form a fine metallic dust. One particular class of thermal spray materials which is used to form wear resistant layers is amorphous and/or nanocrystalline materials. Fe-based amorphous and nanocrystalline materials used in thermal spray contain chromium as an alloying element. Chromium is effective in stabilizing the fine-grained structure, can increase wear resistance through the formation of chromium carbides and/or borides, and is useful in providing a degree of corrosion resistance. However, chromium is considered undesirable for use in thermal spray applications due to the potential to form hexavalent chromium dust. Hexavalent chromium dust is known to cause cancer.
There are several Fe-based chromium free thermal spray materials which have been developed and are used by industry today. Currently available Fe-based Cr-free materials have hardness levels below 500 Vickers, as shown in Table 1, which can make them inapplicable for many different industrial uses.
There have also been efforts to specifically design Cr-free hardfacing materials for welding processes, such as that shown in 2012/0097658. However, the alloys disclosed in the reference require the formation of borides and carbides. Further, the reference requires the use of boron.
Disclosed herein are embodiments of alloy compositions used to produce thermal spray coatings, methods of identifying these compositions, the coatings themselves, and methods of making and using the coatings. Thermal spray coatings according to certain embodiments may be produced having a hardness above 500 Vickers without the use of chromium as an alloying element. Some embodiments are directed to a work piece having a coating on at least a surface, the work piece comprising a metal surface onto which a coating is applied, the coating comprising an Fe-based alloy without any chromium, wherein the alloy comprises a Vickers hardness of at least 500 and an adhesion strength of at least 5,000 psi.
In some embodiments, the coating can be applied via the twin wire arc spray process.
In some embodiments, the coating can comprise, in weight percent, B: about 0-4, C: about 0-0.25, Si: about 0-15, Mn: about 0 to 25, Mo: about 0-29, Nb: about 0-2, Ta: about 0-4, Ti: about 0-4, V: about 0-10, W: about 0-6, Zr: about 0-10, wherein B+C+Si is about 4-15, and wherein (Mo+Mn+Nb+Ta+Ti+V+W+Zr) is about 5 to 38.
In some embodiments, the coating can comprise Fe and, in weight percent, C: about 0 to 0.25, Mn: about 5 to 19, Mo: about 7 to 23, Ni: about 0 to 4, and Si: about 5 to 10.
In some embodiments, the coating can be non-magnetic and therefore the coating thickness can be accurately measured with an Elcometer™ thickness gauge or similar device. In some embodiments, the coating can be non-magnetic and therefore the coating thickness can be accurately measured with an Elcometer™ thickness gauge or similar device after it has been exposed to temperatures exceeding about 1100 K for 2 hours or more and then slow cooled at a rate of 10K/s or less.
In some embodiments, the coating can be amorphous. In some embodiments, the coating can be nanocrystalline, as defined by having a grain size of 100 nm or less.
Also disclosed herein are embodiments of an article of manufacture comprising a coating which is Fe-based, without chromium, and possesses a melting temperature of 1500K or below and a large atom concentration of at least 5 atom %, large atoms being of the group Mn, Mo, Nb, Ta, Ti, V, W, and Zr.
In some embodiments, the coating can comprise a Vickers hardness of at least 400 and an adhesion strength of at least 5,000 psi. In some embodiments, the coating can be applied via the twin wire arc spray process.
In some embodiments, the coating can comprise, in weight percent, B: about 0-4, C: about 0-0.25, Si: about 0-15, Mn: about 0 to 25, Mo: about 0-29, Nb: about 0-2, Ta: about 0-4, Ti: about 0-4, V: about 0-10, W: about 0-6, Zr: about 0-10, wherein B+C+Si is about 4-15, and wherein (Mo+Mn+Nb+Ta+Ti+V+W+Zr) is about 5 to 38.
In some embodiments, the coating can comprise Fe and, in weight percent, C: about 0 to 0.25, Mn: about 5 to 19, Mo: about 7 to 23, Ni: about 0 to 4, and Si: about 5 to 10.
In some embodiments, the coating can be non-magnetic and therefore the coating thickness can be accurately measured with an Elcometer™ thickness gauge or similar device. In some embodiments, the coating can be non-magnetic and therefore the coating thickness can be accurately measured with an Elcometer™ thickness gauge or similar device after it has been exposed to temperatures exceeding about 1100 K for 2 hours or more and then slow cooled at a rate of 10K/s or less.
In some embodiments, the coating can be amorphous. In some embodiments, the coating can be nanocrystalline, as defined by having a grain size of 100 nm or less.
Disclosed herein are embodiments of a work piece having at least one surface, the work piece comprising a coating applied to the at least one surface, the coating comprising an Fe-based alloy having substantially no chromium, having substantially no carbides, and having substantially no borides, wherein the alloy comprises a Vickers hardness of at least 500 and an adhesion strength of at least 5,000 psi.
In some embodiments, the coating can comprise Fe and, in weight percent, B: about 0-4, C: about 0-0.25, Si: about 0-15, Mn: about 0 to 25, Mo: about 0-29, Nb: about 0-2, Ta: about 0-4, Ti: about 0-4, V: about 0-10, W: about 0-6, Zr: about 0-10, wherein B+C+Si is about 4-15, and wherein (Mo+Mn+Nb+Ta+Ti+V+W+Zr) is about 5 to 38. In some embodiments, the coating can comprise Fe and in weight percent, C: about 0 to 0.25, Mn: about 5 to 19, Mo: about 7 to 23, Ni: about 0 to 4, and Si: about 5 to 10. In some embodiments, the coating can comprise one or more of the following compositions in weight percent: Fe, Mn: about 5, Mo: about 13, Si: about 10, Al: about 2; or Fe, Mn: about 5, Mo: about 7, Si: about 10, Al: about 2.
In some embodiments, the coating can be non-magnetic and the coating thickness can be accurately measured with an Elcometer™ thickness gauge or similar device after it has been exposed to temperatures exceeding about 1100 K for 2 hours or more and then slow cooled at a rate of 10K/s or less.
In some embodiments, the coating can be amorphous. In some embodiments, the coating can be nanocrystalline, as defined by having a grain size of 100 nm or less.
In some embodiments, the coating can be applied via a thermal spray process. In some embodiments, the coating can be applied via a twin wire arc spray process. In some embodiments, the work piece can be a yankee dryer. In some embodiments, the work piece can be a roller used in a paper making machine.
Also disclosed herein are embodiments of an article of manufacture comprising an Fe-based coating having substantially no chromium, wherein the coating possesses a melting temperature of 1500K or below, wherein the coating possesses a large atom concentration of at least 5 atom %, large atoms being of the group consisting of Mn, Mo, Nb, Ta, Ti, V, W, and Zr, and wherein the coating is a primarily single phase fine-grained structure of either martensite, ferrite, or austenite.
In some embodiments, the coating can comprise, in weight percent B: about 0-4, C: about 0-0.25, Si: about 0-15, Mn: about 0 to 25, Mo: about 0-29, Nb: about 0-2, Ta: about 0-4, Ti: about 0-4, V: about 0-10, W: about 0-6, Zr: about 0-10, wherein B+C+Si is about 4-15, and wherein (Mo+Mn+Nb+Ta+Ti+V+W+Zr) is about 5 to 38.
In some embodiments, the coating can comprise Fe and in weight percent C: about 0 to 0.25, Mn: about 5 to 19, Mo: about 7 to 23, Ni: about 0 to 4, and Si: about 5 to 10.
In some embodiments, the coating can comprise one or more of the following compositions in weight percent: Fe, Mn: about 5, Mo: about 13, Si: about 10, Al: about 2; or Fe, Mn: about 5, Mo: about 7, Si: about 10, Al: about 2.
In some embodiments, the coating can be non-magnetic and the coating thickness can be accurately measured with an Elcometer™ thickness gauge or similar device after it has been exposed to temperatures exceeding about 1100 K for 2 hours or more and then slow cooled at a rate of 10K/s or less. In some embodiments, the coating can comprise a Vickers hardness of at least 500 and an adhesion strength of at least 5,000 psi.
In some embodiments, the coating can be applied via the twin wire arc spray process. In some embodiments, the coating can be applied via a thermal spray process.
In some embodiments, the coating can be amorphous. In some embodiments, the coating can be nanocrystalline, as defined by having a grain size of 100 nm or less.
In some embodiments, the coating can be applied onto a roller used in a paper making machine. In some embodiments, the coating can be applied onto a Yankee Dryer. In some embodiments, the coating can be applied onto a boiler tube.
Also disclosed herein are embodiments of a work piece having at least one surface, the work piece comprising a coating applied to the at least one surface, the coating comprising an Fe-based alloy having less than 1 wt. % chromium, less than 5 vol. % carbides, and less than 5 vol. % borides, wherein the alloy comprises a Vickers hardness of at least 500 and an adhesion strength of at least 5,000 psi. In some embodiments, the alloy can have less than 1 vol. % carbides and less than 1 vol. % borides.
Disclosed herein are embodiments of chromium free, iron based alloys, and methods of manufacturing the alloys. In some embodiments, the alloys can have high hardness and can be used as, for example, coatings. In some embodiments, computational metallurgy can be used to explore alloy compositional ranges where an alloy is likely to form an amorphous or nanocrystalline coating without the use of chromium as an alloying element. Prior to this disclosure, Fe-based thermal spray coatings with a hardness above 500 Vickers have used chromium as an alloying element. This disclosure demonstrates embodiments of alloy compositions which can produce thermal spray coatings with hardness values above 500 Vickers, in addition to describing the design techniques successfully used to identify them.
Specifically, disclosed herein are embodiments of alloys which can achieve high hardness levels through mechanisms other than the use of chromium or the formation of carbides and/or borides. Rather, in some embodiments, a very fine-grain structure can be achieved due to melting temperature and large atom criteria disclosed herein.
In some embodiments, the alloy can be described by a composition in weight percent comprising the following elemental ranges at least partially based on the ranges disclosed in Table 2 and Table 3:
Generally, embodiments of an alloy can be designed using any of the large elements as long as the other elemental ratios are controlled properly. The following atomic sizes, in picometers, were used for the large elements, large atoms defined as atoms which are larger than iron atoms: Mn: 161, Mo: 190, Nb, 198, Ta: 200, Ti: 176, V: 171, W: 193, Zr: 206. Fe has an atomic size of 156 pm. A large atom can be an atom that is larger than Fe. These large atoms can be advantageous as they can increase the viscosity of an alloy in liquid form and thus slow down the crystallization rate of the alloy. As the crystallization rate decreases, the probability of forming an amorphous, nanocrystalline, or fine-grained structure can increase.
In some embodiments, the coating can be amorphous. In some embodiments, the coating can be nanocrystalline, as defined by having a grain size of 100 nm or less. In some embodiments, the coating can be nanocrystalline, as defined by having a grain size of 50 nm or less. In some embodiments, the coating can be nanocrystalline, as defined by having a grain size of 20 nm or less.
In some embodiments, the alloy can be described by a composition in weight percent comprising the following elemental ranges at least partially based on a range composed form the alloys selected for manufacture into experimental ingots:
In some embodiments, the alloy can be described by the specific compositions, which have been produced and experimentally demonstrated amorphous formation potential, in weight percent, comprising the following elements.
In some embodiments, aluminum can be further added to the above alloy ranges and chemistries to improve coating adhesion in the range of up to 5 (or about 5) wt. %. Some exemplary examples of aluminum additions, based upon the #4 and #5 base chemistries, are:
In some embodiments, the alloy may contain boron, such as between 0-4 wt. % (including 1, 2, and 3 wt. %) as indicated above. In some embodiments, the alloy may not contain any boron. In some embodiments, boron may act as an impurity and does not exceed 1 wt. %.
The Fe content identified in the composition above may be the balance of the composition as indicated above, or alternatively, the balance of the composition may comprise Fe and other elements. In some embodiments, the balance may consist essentially of Fe and may include incidental impurities. In some embodiments, the above alloys may not contain any chromium. In some embodiments, chromium may act as an impurity and does not exceed 1 wt. %.
In some embodiments, the alloy can be described by thermodynamic and kinetic criteria. In some embodiments, the thermodynamic criteria can relate to the stability of the liquid phase, e.g., the melting temperature of the alloy. The melting temperature can be calculated via thermodynamic models and is defined as the highest temperature at which liquid is less than 100% of the mole fraction in the material. The kinetic criterion can be related to the viscosity of the liquid and the concentration in atom percent of large atoms. Large atoms are defined as atoms which are larger than iron atoms. Either or both criteria can be used to predict the tendency towards amorphous formation in thermal spray materials. In some embodiments, the alloys can have a microstructure of ferritic iron. In some embodiments, a primarily single phase fine-grained structure of either martensite, ferrite, or austenite can be formed. In some embodiments, <5% (or <about 5%) borides and carbides are formed. In some embodiments, <1% (or <about 1%) borides and carbides are formed. In some embodiments, <0.1% (or <about 0.1%) borides and carbides are formed. In some embodiments, no borides or carbides are formed.
In some embodiments, the melting temperature can be below 1500 K (or below about 1500K). In some embodiments, the melting temperature can be below 1450K (or below about 1450K). In some embodiments, the melting temperature can be below 1400K (or below about 1400K). In general, amorphous formation is encouraged with lower melting temperatures because, typically, as grain size decreases, hardness increases (known as the Hall-Petch relationship). Amorphous alloys effectively have zero grain size, and thus can be the hardest form of the alloy. As amorphous formation potential increases, the alloy, even if it doesn't always become amorphous in every process, will tend towards a smaller grain size. Thus, amorphous forming alloys of the disclosure, even if they form fine-grained or nanocrystalline structures and not actually an amorphous structure, will tend to be harder. For example, in some embodiments, while there is the potential for an amorphous structure, the alloy may end up being crystalline, specifically nanocrystalline, upon application, such as through thermal spray, while still achieving the high hardness levels disclosed herein.
In some embodiments, the large atom atomic fraction can be above 5 atom % (or above about 5 atom %). In some embodiments, the large atom atomic fraction can be above 7.5 atom % (or above about 7.5 atom %). In some embodiments, the large atom atomic fraction can be above 10 atom % (or above about 10 atom %). In some embodiments, the higher large atom atomic fraction can encourage amorphous formation and increase amorphous formation potential.
Table 2 lists the alloy compositions, all Fe-based, in weight percent which can meet the thermodynamic criteria detailed in this disclosure. In some embodiments, the Fe-based alloys can have a composition that is predominantly iron, e.g., at least 50 wt. % iron.
Combining the alloys in Table 2 and Table 3 yields 1,141 compositions which meet the criteria. These alloys were compiled through computational searching tools which evaluated 16,362 alloys according to the disclosed criteria. Thus, the alloys disclosed cover only 6.9% of the total explored space explicitly investigated to design an alloy with the disclosed performance parameters.
In some embodiments, the alloy can possess a low FCC-BCC transition temperature. This criteria can be related to the likelihood of the alloy to retain an austenitic structure when deposited and thus be ‘readable’ by certain measuring devices, as discussed further below. Readable coatings can be non-magnetic and thus the thickness can be measured with standard paint thickness gauges. This can be advantageous for many thermal spray applications.
In some embodiments, the alloy can be described by performance criteria. The performance criteria that can be advantageous to the field of thermal spray hardfacing is the hardness, wear resistance, coating adhesion, and corrosion resistance.
In some embodiments, the Vickers hardness of the coating can be 400 or above (or about 400 or above). In some embodiments, the Vickers hardness of the coating can be 500 or above (or about 500 or above). In some embodiments, the Vickers hardness can be 550 or above (or about 550 or above). In some embodiments, the Vickers hardness can be 600 or above (or about 600 or above). The specific microstructure disclosed herein can allow for embodiments of the alloys to have high hardness.
In some embodiments, the adhesion strength of the coating can be 5,000 psi or above (or about 5,000 psi or above). In some embodiments, the adhesion strength of the coating can be 7,500 psi or above (or about 7,500 psi or above). In some embodiments, the adhesion strength of the coating can be 10,000 psi or above (or about 10,000 psi or above).
In some embodiments, the abrasion resistance of the coating as measured via ASTM G65B testing can be 0.8 grams loss or below (or about 0.8 grams loss or below). In some embodiments, the abrasion resistance of the coating as measured via ASTM G65B testing can be 0.6 grams loss or below (or about 0.6 grams loss or below). In some embodiments, the abrasion resistance of the coating as measured via ASTM G65B testing can be 0.4 grams loss or below (or about 0.4 grams loss or below).
In some embodiments, the adhesive wear resistance of the coating as measured via ASTM G77 testing, hereby incorporated by reference in its entirety, can be 2 mm3 volume loss or below (or about 2 mm3 volume loss or below). In some embodiments, the adhesive wear resistance of the coating as measured via ASTM G77 testing can be 0.5 mm3 volume loss or below (or about 0.5 mm3 volume loss or below). In some embodiments, the adhesive wear resistance of the coating as measured via ASTM G77 testing can be 0.1 mm3 volume loss or below (or about 0.1 mm3 volume loss or below).
In some embodiments, the alloy can exhibit similar performance to conventional Cr-bearing thermal spray materials used for hardfacing. The most exemplary and well used thermal spray hardfacing material possesses a chemical composition of Fe: BAL, Cr: 29, Si: 1, Mn: 2, B: 4, which is generally referred to in the industry as Armacor M. Armacor M possesses the following properties which are relevant to thermal spray hardfacing: adhesion of about 8,000 psi, ASTM G65B mass loss of about 0.37 grams, ASTM G77 volume loss of about 0.07 mm3, and position in the galvanic series in saltwater of about −500 mV. Armacor M is primarily made of Fe, Cr, and B, has a high melting temperature, and has no large atoms.
In some embodiments of this disclosure, the alloys can exhibit similar coating adhesion and abrasive wear resistance as Armacor, where ‘similar’ equates to within 25% (or within about 25%) of the measured performance properties of Armacor M or better. In some embodiments of this disclosure, the alloys can exhibit similar coating adhesion, abrasive wear resistance, and adhesive wear resistance as Armacor, where ‘similar’ equates to within 25% (or within about 25%) of the measured performance properties of Armacor M or better. In some embodiments of this disclosure, the alloys can exhibit similar coating adhesion, abrasive wear resistance, adhesive wear resistance, and corrosion resistance as Armacor, where ‘similar’ equates to within 25% (or within about 25%) of the measured performance properties of Armacor M or better.
In some embodiments of this disclosure, the alloys can exhibit similar coating adhesion and abrasive wear resistance as Armacor, where ‘similar’ equates to within 10% (or within about 10%) of the measured performance properties of Armacor M or better. In some embodiments of this disclosure, the alloys can exhibit similar coating adhesion, abrasive wear resistance, and adhesive wear resistance as Armacor, where ‘similar’ equates to within 10% (or within about 10%) of the measured performance properties of Armacor M or better. In some embodiments of this disclosure, the alloys can exhibit similar coating adhesion, abrasive wear resistance, adhesive wear resistance, and corrosion resistance as Armacor, where ‘similar’ equates to within 10% (or within about 10%) of the measured performance properties of Armacor M or better.
In some embodiments of this disclosure, the alloys can exhibit similar coating adhesion and abrasive wear resistance as Armacor, where ‘similar’ equates to within 1% (or within about 1%) of the measured performance properties of Armacor M or better. In some embodiments of this disclosure, the alloys can exhibit similar coating adhesion, abrasive wear resistance, and adhesive wear resistance as Armacor, where ‘similar’ equates to within 1% (or within about 1%) of the measured performance properties of Armacor M or better. In some embodiments of this disclosure, the alloys can exhibit similar coating adhesion, abrasive wear resistance, adhesive wear resistance, and corrosion resistance as Armacor, where ‘similar’ equates to within 1% (or within about 1%) of the measured performance properties of Armacor M or better.
In some embodiments of this disclosure, the alloys can exhibit similar coating adhesion and abrasive wear resistance as Armacor, where ‘similar’ equates to within 0% (or within about 0%) of the measured performance properties of Armacor M or better. In some embodiments of this disclosure, the alloys can exhibit similar coating adhesion, abrasive wear resistance, and adhesive wear resistance as Armacor, where ‘similar’ equates to within 0% (or within about 0%) of the measured performance properties of Armacor M or better. In some embodiments of this disclosure, the alloys can exhibit similar coating adhesion, abrasive wear resistance, adhesive wear resistance, and corrosion resistance as Armacor, where ‘similar’ equates to within 0% (or within about 0%) of the measured performance properties of Armacor M or better.
In some embodiments, the thermal spray coating can be ‘readable’. A readable coating produces consistent thickness measurements with an Elcometer™ thickness gauge, or similar device, when properly calibrated. Armacor M is not a readable alloy, unlike embodiments of the disclosure, as it is magnetic.
As a standard to verify ‘readability’, a 25 mil standard thermal spray coupon is used for measurements. In some embodiments, the coating thickness measurement can be accurate to within 5 mils (or within about 5 mils) of the actual physical thickness. In some embodiments, the coating thickness measurement can be accurate to within 3.5 mils (or within about 3.5 mils) of the actual physical thickness. In some embodiments, the coating thickness measurement can be accurate to within 2 mils (or within about 2 mils) of the actual physical thickness.
In some embodiments, consistent measurements according to the above criteria, ±5 mils to actual physical thickness, can be made after the coating has been exposed to heat for an extended period of time. This can be advantageous because when the alloy is heated, there is a potential for a magnetic phase to precipitate out, which would make the alloy non-readable. This can be especially true for amorphous alloys which may be readable in amorphous form, but may crystallize in a different environment due to heat. Thus, in some embodiments, the alloy can remain non-magnetic even after being exposed to heat for a substantial time period.
In some embodiments, the coating can be ‘readable’ after exposure to 1100K (or about 1100K) for 2 hours (or about 2 hours) and cooled at a rate of less than 10K/S (or less than about 10K/S). In some embodiments, the coating can be ‘readable’ after exposure to 1300K (or about 1300K) for 2 hours (or about 2 hours) and cooled at a rate of less than 10K/S (or less than 10K/S). In some embodiments, the coating can be ‘readable’ after exposure to 1500K (or about 1500K) for 2 hours (or about 2 hours) and cooled at a rate of less than 10K/S (or less than about 10K/S). It is expected that increased exposure times above 2 hours will not continue to affect the final ‘readability’ of these materials.
Embodiments of alloys disclosed herein can be used in a variety of applications and industries. Some non-limiting examples of applications of use include:
Surface mining applications including but not limited to the following components and coatings for the following components: wear resistant sleeves and/or wear resistant hardfacing for slurry pipelines, mud pump components including pump housing or impeller or hardfacing for mud pump components, ore feed chute components including chute blocks or hardfacing of chute blocks, separation screens including but not limited to rotary breaker screens, banana screens, and shaker screens, liners for autogenous grinding mills and semi-autogenous grinding mills, ground engaging tools and hardfacing for ground engaging tools, wear plate for buckets and dumptruck liners, heel blocks and hardfacing for heel blocks on mining shovels, grader blades and hardfacing for grader blades, stacker reclaimers, siazer crushers, general wear packages for mining components and other communition components.
Upstream oil and gas applications including but not limited to the following components and coatings for the following components: Downhole casing and downhole casing, drill pipe and coatings for drill pipe including hardbanding, mud management components, mud motors, fracking pump sleeves, fracking impellers, fracking blender pumps, stop collars, drill bits and drill bit components, directional drilling equipment and coatings for directional drilling equipment including stabilizers and centralizers, blow out preventers and coatings for blow out preventers and blow out preventer components including the shear rams, oil country tubular goods and coatings for oil country tubular goods.
Downstream oil and gas applications including but not limited to the following components and coatings for the following components: Process vessels and coating for process vessels including steam generation equipment, amine vessels, distillation towers, cyclones, catalytic crackers, general refinery piping, corrosion under insulation protection, sulfur recovery units, convection hoods, sour stripper lines, scrubbers, hydrocarbon drums, and other refinery equipment and vessels.
Pulp and paper applications including but not limited to the following components and coatings for the following components: Rolls used in paper machines including yankee dryers and other dryers, calendar rolls, machine rolls, press rolls, digesters, pulp mixers, pulpers, pumps, boilers, shredders, tissue machines, roll and bale handling machines, doctor blades, evaporators, pulp mills, head boxes, wire parts, press parts, M.G. cylinders, pope reels, winders, vacuum pumps, deflakers, and other pulp and paper equipment.
Power generation applications including but not limited to the following components and coatings for the following components: boiler tubes, precipitators, fireboxes, turbines, generators, cooling towers, condensers, chutes and troughs, augers, bag houses, ducts, ID fans, coal piping, and other power generation components.
Agriculture applications including but not limited to the following components and coatings for the following components: chutes, base cutter blades, troughs, primary fan blades, secondary fan blades, augers and other agricultural applications.
Construction applications including but not limited to the following components and coatings for the following components: cement chutes, cement piping, bag houses, mixing equipment and other construction applications.
Machine element applications including but not limited to the following components and coatings for the following components: Shaft journals, paper rolls, gear boxes, drive rollers, impellers, general reclamation and dimensional restoration applications and other machine element applications.
Steel applications including but not limited to the following components and coatings for the following components: cold rolling mills, hot rolling mills, wire rod mills, galvanizing lines, continue pickling lines, continuous casting rolls and other steel mill rolls, and other steel applications.
Embodiments of alloys disclosed herein can be produced and or deposited in a variety of techniques effectively. Some non-limiting examples of processes include:
Thermal spray process including but not limited to those using a wire feedstock such as twin wire arc, spray, high velocity arc spray, combustion spray and those using a powder feedstock such as high velocity oxygen fuel, high velocity air spray, plasma spray, detonation gun spray, and cold spray. Wire feedstock can be in the form of a metal core wire, solid wire, or flux core wire. Powder feedstock can be either a single homogenous alloy or a combination of multiple alloy powder which result in the desired chemistry when melted together.
Welding processes including but not limited to those using a wire feedstock including but not limited to metal inert gas (MIG) welding, tungsten inert gas (TIG) welding, arc welding, submerged arc welding, open arc welding, bulk welding, laser cladding, and those using a powder feedstock including but not limited to laser cladding and plasma transferred arc welding. Wire feedstock can be in the form of a metal core wire, solid wire, or flux core wire. Powder feedstock can be either a single homogenous alloy or a combination of multiple alloy powder which result in the desired chemistry when melted together.
Casting processes including but not limited to processes typical to producing cast iron including but not limited to sand casting, permanent mold casting, chill casting, investment casting, lost foam casting, die casting, centrifugal casting, glass casting, slip casting and process typical to producing wrought steel products including continuous casting processes.
Post processing techniques including but not limited to but not limited to rolling, forging, surface treatments such as carburizing, nitriding, carbonitriding, heat treatments including but not limited to austenitizing, normalizing, annealing, stress relieving, tempering, aging, quenching, cryogenic treatments, flame hardening, induction hardening, differential hardening, case hardening, decarburization, machining, grinding, cold working, work hardening, and welding.
One of the more applicable uses of this technology is in applications where coatings are deposited on-site, in the field, or in locations where proper ventilation, dust collection, and other safety measures cannot be easily met. Some well-known non-limiting examples of these applications include power generation applications such as the coating of boiler tubes, upstream refinery applications such as the coating of refinery vessels, and pulp and paper applications such as the coating and grinding of yankee dryers.
The following examples are intended to be illustrative and non-limiting.
The previously disclosed alloy #4, Fe: BAL, Mn: about 5, Mo: about 13, Si: about 10 was produced in the form of a 40 gram trial ingot to verify hardness and thermal spray vitrification potential. The ingot hardness was measured to be 534 Vickers (converting from a Rockwell C measurement). The microstructure of the ingot showed a fully eutectic structure indicating a strong possibility for amorphous or nanocrystalline structure under the rapid cooling rate of the spray process. This material has been selected for manufacture into 1/16″ cored thermal spray wire for twin wire arc spray trials after slight modification to the alloy #14, Fe: BAL, Mn: about 5, Mo: about 13, Si: about 10, Al: about 2.
The previously presented alloy #5, Fe: BAL, Mn: about 5, Mo: about 7, Si: about 10 was produced in the form of a 40 gram trial ingot to verify hardness and thermal spray vitrification potential. The ingot hardness was measured to be 534 Vickers (converting from a Rockwell C measurement). The microstructure of the ingot showed a fully eutectic structure indicating a strong possibility for amorphous or nanocrystalline structure under the rapid cooling rate of the spray process. This material has been selected for manufacture into 1/16″ cored thermal spray wire for twin wire arc spray trials after slight modification to alloy #15, Fe: BAL, Mn: about 5, Mo: about 7, Si: about 10, Al: about 2.
The previously disclosed alloy #8, Fe: BAL, C: about 0.25, Mn: about 19, Mo: about 7, Si: about 5 was produced in the form of a 40 gram ingot to verify hardness, thermal spray vetrification potential and magnetic permeability. In this example, the alloy candidate is being developed as a ‘readable’ coating which requires the alloy to be non-magnetic in the sprayed form. The ingot hardness was measured to be 300 Vickers (converting from a Rockwell C measurement). While this is below the desired hardness threshold, it is well known by those skilled in the art that the rapid cooling process achieved in thermal spray will increase the hardness of the alloy in this form. Thus, it is not unreasonable to expect an increase in hardness in the sprayed form up to the desired level of 400 Vickers. The relative magnetic permeability was measured via a Low-Mu Magnetic Permeability Tester and was determined to be less than 1.01, well below the threshold required to ensure ‘readability’.
The previously disclosed alloy #5, Fe: BAL, Mn: about 5, Mo: about 7, Si: about 10 was produced in the form of a cored thermal spray wire. This alloy was sprayed using the twin wire arc spray technique, specifically using the parameters shown in
Table 3. A series of tests were run to evaluate the alloys performance in reference to standard Cr-bearing thermal spray materials used for hardfacing. The specific alloy of reference is known by the commercial names, Armacor M, TAFA 95MXC, PMet 273, etc. and has an alloy composition of about Fe: BAL, Cr: 29, Si: 1, Mn: 2, B: 4. Table 2 highlights the result of the testing. As shown in Table 4, Alloy #5 has comparable adhesion and abrasion resistance as measure via ASTM G65B testing.
The previously disclosed alloy #4, Fe: BAL, Mn: about 5, Mo: about 7, Si: about 10 was produced in the form of a cored thermal spray wire. This alloy was sprayed using the twin wire arc spray technique using the parameters shown in
Table 3. Yankee dryers are typically sprayed using this parameter set. A series of tests were run to evaluate the alloys performance in reference to standard Cr-bearing thermal spray materials used for hardfacing similar to that described in Example 4. The preliminary results of this testing are shown in Table 2.
As shown, Alloy #4 replicates the key performance criteria of Armacor M in all key criteria. As Alloy #4 represents an exemplary embodiment of this disclosure, additional testing was performed in order to compare other performance criteria specifically as it relates to the coating of yankee dryers, a specific article of manufacture used in paper machines. This testing including corrosion testing, grinding studies, spray characteristics, thorough metallographic evaluation, and evaluation of surface properties as related to surface tension. In all cases, alloy #4 was deemed to have similar or better performance than the Armacor M coating.
Corrosion testing was conducted by exposing the coating to saltwater and measuring the voltage against a reference bare steel plate, which could be then used to place the material on the Galvanic Series. Both the Armacor M and Alloy #4 coatings showed significant rust on the coating surface after the 2 week test exposure. The position of the Armacor M coating on the galvanic series is −450 to −567 and the position of Alloy #4 is −510 to −640. Increasingly negative values reflect more active potentials, which is less desirable as it indicates reduced corrosion resistance. This represents a ‘similarity’ in that the quantified performance does not vary by more than 25%.
Grinding studies were performed due to its specific relevance to the yankee dryer application. In this application it is desirable for the coating to exhibit faster grinding times, as it reduces the downtime of the paper machine. Grinding times were quantified by removing a specific material thickness and measuring the tie to do so, as shown in
Table 4. As shown, Alloy #4 showed reduced grinding time, which is advantageous.
The characteristics of the spray for both materials was also studied. It was evident that Alloy #4 produced significantly less dust during spraying than Armacor M, which is desirable. Metallographic examination also showed that less oxides were present in the Alloy #4 coating, 7% versus 13% in the Armacor M coating.
Finally the surface tension properties of each coating were evaluated. In the Yankee dryer application it is desirable for the coating to be hydrophilic, which enables the adsorption of water based organic compounds used in paper making into the surface. The contact angle that a water droplet makes on the surface can be used to quantify the surface tension of the material. The Armacor M water droplet formed a 63.9° angle, and Alloy #4 formed a 41.5° angle. A smaller angle indicates increased hydrophillicity, which is advantageous because in Yankee dryer applications, a monoammonium phosphate (MAP) water-based solution is typically sprayed onto the coating for paper release properties. It can be advantageous for this water-based solution to immerse itself into the coating structure and stick well to the coating surface, which can be enhanced by having a hydrophilic coating.
From the foregoing description, it will be appreciated that an inventive chromium free hardfacing alloy and method of manufacturing are disclosed. While several components, techniques and aspects have been described with a certain degree of particularity, it is manifest that many changes can be made in the specific designs, constructions and methodology herein above described without departing from the spirit and scope of this disclosure.
Certain features that are described in this disclosure in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as any subcombination or variation of any subcombination.
Moreover, while methods may be depicted in the drawings or described in the specification in a particular order, such methods need not be performed in the particular order shown or in sequential order, and that all methods need not be performed, to achieve desirable results. Other methods that are not depicted or described can be incorporated in the example methods and processes. For example, one or more additional methods can be performed before, after, simultaneously, or between any of the described methods. Further, the methods may be rearranged or reordered in other implementations. Also, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described components and systems can generally be integrated together in a single product or packaged into multiple products. Additionally, other implementations are within the scope of this disclosure.
Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include or do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments.
Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z.
Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than or equal to 10% of, within less than or equal to 5% of, within less than or equal to 1% of, within less than or equal to 0.1% of, and within less than or equal to 0.01% of the stated amount. If the stated amount is 0 (e.g., none, having no), the above recited ranges can be specific ranges, and not within a particular % of the value. For example, within less than or equal to 10 wt./vol. % of, within less than or equal to 5 wt./vol. % of, within less than or equal to 1 wt./vol. % of, within less than or equal to 0.1 wt./vol. % of, and within less than or equal to 0.01 wt./vol. % of the stated amount.
Some embodiments have been described in connection with the accompanying drawings. The figures are drawn to scale, but such scale should not be limiting, since dimensions and proportions other than what are shown are contemplated and are within the scope of the disclosed inventions. Distances, angles, etc. are merely illustrative and do not necessarily bear an exact relationship to actual dimensions and layout of the devices illustrated. Components can be added, removed, and/or rearranged. Further, the disclosure herein of any particular feature, aspect, method, property, characteristic, quality, attribute, element, or the like in connection with various embodiments can be used in all other embodiments set forth herein. Additionally, it will be recognized that any methods described herein may be practiced using any device suitable for performing the recited steps.
While a number of embodiments and variations thereof have been described in detail, other modifications and methods of using the same will be apparent to those of skill in the art. Accordingly, it should be understood that various applications, modifications, materials, and substitutions can be made of equivalents without departing from the unique and inventive disclosure herein or the scope of the claims.
| Number | Date | Country | |
|---|---|---|---|
| 62028706 | Jul 2014 | US |
