Patent Application
20130156633
Not applicable.
The present invention is in the field of aluminum and aluminum composites.
Heat-treating of aluminum parts is common practice, but one which is limited because it typically involves immersion of the aluminum part in high carbon concentration liquids which produces surface hardness but leaves a soft aluminum core. The resulting heat-treated aluminum parts have obvious deficiencies due to the inner core that was not hardened by the heat-treatment process. Heat-treating of 20 metals, e.g., steel, is known to depend upon the carbon content of the metal. Unless the carbon content of the aluminum can be increased, it cannot be hardened to the same degree as can, for example, steel.
The need to materials that are strong and lightweight is obvious. Traditional materials that were lightweight were not sufficiently strong, and those that were 25 strong, were too heavy. For example, the automotive industry would like to reduce the weight of vehicles to improve fuel economy without sacrificing safety and without prohibitively increasing the cost of the vehicle. Aluminum offers the weight reduction that they seek, but not the hardness of the steel that it replaces.
Heretofore, U.S. Pat. No. 5,401,338 proposes to make an aluminum alloy 30 matrix composition by forming a heated, ultrasonically oscillated reinforcing material (Al2O3, SiC, SiN, etc.) aqueous suspension, which is sprayed onto the surface of heated aluminum held under continuous agitation. Degassing follows this procedure.
U.S. Pat. No. 5,021,087 proposes to improve the casting properties of aluminum by placing a hydrogen-containing treating gas blanket over molten aluminum. U.S. Pat. No. 5,376,160 proposes to alloy Ti, Mo, B with iron or steel by adding granules of the iron or steel that encapsulate decomposable organic polymers (polyethylene, polypropylene, polystyrene) and the alloying metal. The molten iron or steel melts the granules, which releases the organic polymers that decompose into gas that agitates the melt.
U.S. Pat. No. 4,159,906 proposes to desulfurize pig iron with calcium carbide or calcium cyanamide and an agent (polyethylene, polyamide) that releases water or hydrogen at molten pig iron temperatures.
The present invention is addressed to hardening the complete hardening of aluminum parts.
The present invention relates generally to aluminum composite compositions and more particularly to an aluminum composite composition of increased homogeneous carbon content and/or that includes discreet phases of steel, and that may be used as a heat-treatable material that is harder, tougher, and lighter per volume than standard aluminum.
In general terms, the invention includes a method for incorporating carbon homogeneously into an aluminum feedstock for forming a hardened aluminum product, which comprises the steps of: (a) providing a molten aluminum feedstock; (b) mixing a material selected from the group consisting of organic compounds and carbonaceous materials with said molten aluminum while running electric current through said molten aluminum; and (c) recovering said hardened aluminum product with carbon homogeneously dispersed throughout.
The method may use any organic compound(s) or carbonaceous materials, such as those selected from the group consisting of powdered carbon, charcoal, activated carbon, polyethylene, polypropylene, polystyrene, thermally decomposable organic polymers, and mixtures thereof.
Preferably, the mixing step is conducted at a temperature ranging from about 1250° to 2000° F., preferably from about 1400° to 2000° F. In the case where more flammable carbon sources are used, such as in the case of polymeric materials, the mixing preferably is carried out under an inert atmosphere to reduce the danger attendant to ignition of the material. An inert atmosphere may be in the form of one or more of argon, nitrogen, or carbon dioxide.
The current typically is provided by contacting the aluminum melt with an anode and a cathode so as to provide a current therethrough. It is preferred that the current is of a voltage ranging from between about 12 and 200 volts, and that the current is DC current. In the case where an organic compound is used, it is preferred that it be molten and subjected to a negative charge prior to being mixed with the positively charged molten aluminum feedstock.
It is also preferred that the carbon is present in an amount in the range of between about 0.08 and about 3.5 weight-percent although it may be higher than 3.5 weight-percent, such as in the range of between about 0.08 and about 10.0 weight-percent.
The resulting hardened aluminum product is characterized by a density less than that of 99.5% pure aluminum, and hardness greater than that of 99.5% pure aluminum.
The present invention also includes a method for incorporating carbon homogeneously into an aluminum feedstock for forming a hardened aluminum product, as set forth above which results in the production and recovery of hardened aluminum product with discrete phases of steel homogeneously dispersed throughout. The discrete phase of steel within said hardened aluminum product preferably are present in an amount in the range equivalent to between about 0.08 and about 10.0 weight-percent of carbon.
The present invention also includes the product of these methods and processes.
The invention further includes a hardened aluminum composition comprising an aluminum matrix and discrete phases of steel within said aluminum matrix; typically dispersed substantially homogeneously throughout said aluminum matrix. Another aspect of the compositions of the present invention is the decreased density and/or increased hardness as compared to pure aluminum occasioned by the incorporation of carbon, such as in the form of discrete phases of steel. This composition has a density less than that of 99.5% pure aluminum, and hardness greater than that of 99.5% pure aluminum. The invention further includes a hardened aluminum product comprising a substantially pure aluminum matrix having carbon homogeneously dispersed throughout and having a density less than that of 99.5% pure aluminum; and having hardness greater than that of 99.5% pure aluminum.
One aspect of the invention is a method for incorporating carbon homogeneously into aluminum materials. The first step is to apply a positive charge to molten aluminum. Next, a negative charge is applied to an organic compound. Under an inert atmosphere, the negatively charged organic compound is mixed with the positively charged molten aluminum while running electric current therethrough. An aluminum material with carbon homogeneously dispersed throughout is recovered.
Although not intended to be limited by theory, it is believed that conducting current through the carbon-containing aluminum melt may cause the formation of complex carbides, such as magnesium, copper or iron carbides, typically those being double-bonded carbides.
It has also been found that carbon is incorporated into the aluminum through the process of the present invention such that the carbon actually comes into solution in the aluminum melt rather than being disposed at grain boundaries.
Other objects, features, and advantages of the present invention will become apparent to those skilled in the art from the following detailed description and accompanying drawings. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not limitation. Many modifications and changes within the scope of the present invention may be made without departing from the spirit thereof, and the invention includes all such modifications.
In accordance with the foregoing summary of the invention, the following presents a detailed description of the preferred embodiments, which are considered to be the best mode thereof.
The invention increases the amount of carbon molecules present in the aluminum matrix. While prior processes could surface harden aluminum, the invention has the ability to distribute the carbon molecules throughout the aluminum matrix; thus, hardening the entire aluminum matrix. Hardened aluminum is tougher and stronger than untreated Al. Moreover, such hardened Al maintains its lightness in weight, because the added hardening material is carbon (molecular weight of 12). In fact, the density of the novel hardened Al is less than untreated Al (e.g., 99.5% Al) by dint of the presence of carbon molecules in the matrix.
Aluminum also is prized in industry due to its machinability. The novel hardened Al has the same ease of machinability as does untreated Al. The novel hardened Al also can be cast, molded, extruded, and otherwise processed just as pure Al and Al alloys. Thus, uses of the novel hardened Al are expected to be the same as Al is today with substitution for steel (e.g., automotive or other industrial application) likely. The first step in manufacturing the novel hardened Al is to form a melt of Al. This most conveniently is accomplished by melting the Al feedstock in a crucible at a temperature ranging from about 1400° F. to 2000° F. Conventional equipment and handling procedures are practiced in this step. The Al feedstock can be an alloy or can be pure (99.5%, for example) aluminum. Examples for aluminum feedstock that may be used include 6061 and 356 aluminum alloys.
Next, electrodes are placed in the Al melt. Steel or other conventional material is used for the electrodes. The electrodes are connected to a source of voltage 10 ranging from about 12 to 200 volts. While DC current is preferred, AC current will function to harden the Al feedstock.
A source of carbonaceous or organic material is provided. The carbonaceous source can be virtually any convenient carbon source. The carbonaceous material, however, is not a metal carbide or ceramic carbide, which are conventional reinforcements for aluminum. For present purposes, then, “organic compound” comprehends carbonaceous materials substantially devoid of organometallic content. For example, virtually any thermally decomposable organic polymer can be used including, for example, one or more of polyethylene, polypropylene, polystyrene, or the like. Preferably, the Al feedstock will be positively charged and a source of carbon will be negatively charged before being mixed. A source of carbonaceous or organic material may also be powdered carbon, charcoal and/or activated carbon, and mixtures thereof.
Before mixing the Al feedstock with the carbonaceous material, an inert gas atmosphere is established above the Al melt. Any convenient inert gas can be used, such as, for example, argon, nitrogen, carbon dioxide, or the like. This inert gas blanket controls the flames from the carbonaceous material added to the Al melt.
Next, the carbonaceous material is added to the Al melt, desirably in small aliquots while the Al melt is being stirred. The electrodes can accomplish stirring if necessary, desirable, or convenient. Heat can be added to the mixture, as needed, in order to maintain the desired temperature of the melt. If the mixture becomes difficult to stir (viscous), the temperature of the mixture can be increased.
Testing has proved that the weight of the product is greater than the Al feedstock weight. Carbon has been incorporated into the Al matrix. Such carbon incorporation will be generally homogeneous if adequate mixing of the materials has been achieved.
Once the carbonaceous material has been added, the mixture can be additionally heated, if necessary, to pouring temperature and the product cast, molded, extruded, or otherwise formed into an intermediate or final product. Importantly, carbon has been incorporated into the Al matrix for its hardening.
While the invention has been described with reference to a preferred embodiment, those skilled in the art will understand that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. In this application all units are in the metric system and all amounts and percentages are by weight, unless otherwise expressly indicated. Also, all citations referred herein are expressly incorporated herein by reference.
Aluminum (2,443 g) was melted at 1450° F. in a crucible. An inert atmosphere (argon gas) was maintained over the aluminum melt. Aliquots of low-density polyethylene (LDPE) were made in approximately 100 g additions. After the initial melt temperature was reached, heating was discontinued. Reheating of the melt was undertaken periodically as detailed below.
Two steel probes were immersed into the Al melt and connected to a 12-volt DC battery. Three additions of the LDPE were made to the charged Al melt. The furnace was fired up to bring the melt temperature up to 1550° F.
After another three additions of LDPE, the furnace again was fired up to bring the melt temperature up to 1550° F.
After another five additions of LDPE, the furnace once again was fired up to bring the melt temperature up to 1550° F.
At this time the 12-volt battery source was removed and a Hobart welder (100 volts) was connected to the melt through the two steel probes (electrodes). The last two additions of LDPE were made at this time.
The Al melt then was poured into sand molds to form an ingot. The remaining melt in the crucible was cooled and weighed. The total weight for the melt residue in the crucible and the ingot was 2,453 g. Given the initial Al weight in the crucible was 2,443 g, this means that 10 g of LDPE was incorporated into the Al melt in the crucible.
The ingot was subjected to hardness testing using a Rockwell Hardness tester calibrated on a 63.8 gage block that tested at 64.1. The minor load used was 10 kg and the major load used was 150 kg.
In this example, the Al melted in the crucible weighed 2451 g and 1553 g of 15 LDPE was added thereto in the same manner as described in connection with Example 1. In this example, however, a 100-volt AC source was used. It was observed that burn off seemed to take longer with AC current compared to OC current. Moreover, only 2 g of LDPE was incorporated into the Al melt.
Example 2 was repeated, but OC voltage was used with 2451 g of Al and 1553 g of LDPE. The initial Al melt temperature was 1550° F. A 100-volt OC current source again was used.
After the initial 4 additions of LDPE, the melt temperature was raised to 1600° F.
After an additional 3 additions of LDPE, the temperature of the melt in the crucible was raised to 1700° F.
After an additional 3 additions of LDPE, the temperature of the melt in the crucible was raised to 1700° F. The melt in the crucible was thickening and mixing 30 seemed to be better than with the AC current.
After an additional 4 additions of LDPE, the temperature of the melt in the crucible was raised to 1750° F.
After the final 3 additions of LDPE were made, the material in the crucible was heated to pouring fluidity and an ingot was cast in a sand mold.
The total weight of the ingot and residual material in the crucible was 2543 g. This means that 92 g of LDPE was incorporated into the Al. The ingot had a Rockwell hardness value of about 130 (C Scale).
A total of 2280 g of Al was melted in the crucible. The current source was 120-volts DC and the total amount of LDPE to be added was 1553 g.
After the initial 3 additions of LDPE, the temperature of the crucible contents was raised to 1700 ° F.
After an additional 2 additions of LDPE, the material became too thick, so the temperature was raised to 1600° F.
After the additional 3 additions of LDPE, the temperature of the crucible contents was raised to 1600° F.
After the additional 2 additions of LDPE, the temperature of the crucible contents was raised to 1700° F.
After the additional 3 additions of LDPE, the temperature of the crucible contents was raised to 1700° F.
After the final 3 additions of LDPE, the material was heated to 1700° F. and an ingot was poured.
The total weight of material (ingot plus crucible residue) was 2296 g, indicating an incorporation of 16 g of material from the LDPE. Rockwell hardness readings of the ingot ranged from about 135.4 to 158.2 (C scale).
A total of 2280 g of Al and 1553 of LDPE was used in this example with the DC current source set at 150 volts DC. The initial melt temperature of the Al was 1500° F.
After the initial 3 additions of LDPE, the temperature of the crucible contents was raised to 1700° F.
After the additional 3 additions of LDPE, the temperature of the crucible contents was raised to 1700° F.
After the additional 4 additions of LDPE, the temperature of the crucible contents was raised to 1700° F.
After the additional 4 additions of LDPE, the temperature of the crucible contents was raised to 1700° F.
After the additional 3 additions of LDPE, the temperature of the crucible contents was raised to 1700° F.
After the final 3 additions of LDPE, the temperature of the crucible contents was raised to 1700° F. for casting.
The total weight of material (ingot plus crucible residue) was 2308 g, indicating an incorporation of 28 g of material from the LDPE.
A total of 2280 g of Al and 1553 of LDPE was used in this example with the DC current source set at 200 volts DC. The initial melt temperature of the Al was 1500° F.
After the initial 3 additions of LDPE, the temperature of the crucible contents was raised to 1700° F. The material was considerably thicker than in the other runs. It appears that with higher voltages, more material is being incorporated into the melt. Thus, the temperature was raised to 1800° F.
After the additional 3 additions of LDPE, the temperature of the crucible contents was raised to 1800° F.
After the additional 4 additions of LDPE, the temperature of the crucible contents was raised to 1800° F.
After the additional 3 additions of LDPE, the temperature of the crucible contents was raised to 1800° F.
After the final 3 additions of LDPE, the temperature of the crucible contents 25 was raised to 1800° F. for casting.
The total weight of material (ingot plus crucible residue) was 2299 g, indicating an incorporation of 19 g of material from the LDPE.
Example 7
A total of 2286 g of Al and 1553 of LDPE was used in this example with the DC current source set at 200 volts DC. The initial melt temperature of the Al was 2000° F.
After the initial 7 additions of LDPE, the temperature of the crucible contents was raised to 1700° F.
After the additional 4 additions of LDPE, the temperature of the crucible contents was raised to 1700° F.
After the additional 4 additions of LDPE, the temperature of the crucible contents was raised to 1700° F.
After the additional 3 additions of LDPE, the temperature of the crucible contents was raised to 1700° F.
After the final 2 additions of LDPE, the temperature of the crucible contents was raised to 1700° F. for casting.
The total weight of material (ingot plus crucible residue) was 2296 g, indicating an incorporation of 10 g of material from the LDPE.
A total of 2280 g of Al and 1553 of LDPE was used in this example with the DC current source set at 150 volts DC. The initial melt temperature of the Al was 1700 ° F.
After the initial 6 additions of LDPE, the temperature of the crucible contents was raised to 1700° F.
After the additional 4 additions of LDPE, the temperature of the crucible contents was raised to 1700° F.
After the additional 3 additions of LDPE, the temperature of the crucible contents was raised to 1700° F.
After the additional 4 additions of LDPE, the temperature of the crucible contents was raised to 1700° F.
After the final 2 additions of LDPE, the temperature of the crucible contents was raised to 1700° F. for casting.
The total weight of material (ingot plus crucible residue) was 2300 g, indicating an incorporation of 20 g of material from the LDPE.
All of the leftovers from Examples 1-8 were reheated and an ingot poured. The ingot weighed 5590 g and the leftover in the crucible as 2692 g. At 2000° F., the ingot still could not be poured. The thermometer used could not register over 2000° F. Nevertheless, heating was continued until the material was fluent enough to pour the ingot.
Sand cast ingots cast from additional runs were subjected to evaluation. Test pieces were machined into various sizes using a 115″ vertical band saw with a fine toothed blade (between 16 and 22 teeth). Each test piece was assigned a serial number, as set forth below (only those test pieces evaluated will be displayed, rather than all the test pieces made):
Some of these test pieces were machined using a ⅞″ HSS 4 flute 3″ cutter at a low spindle speed of 800 rpm and a feed rate restricted to about 6 in/min. This cutter performed well. The chips produced were approximately ½ to ¾ inches in length with a thickness ranging from about 0.003 to 0.005 in. The machinist reported that the samples had the feel of 6000 series aluminum.
The second cutter was a ¾″ HSS 6 flute 2⅕″ cutter. The feed rate was slowed to 6 in/min to keep the cutter from binding up. This caused vibrations in the machine, which resulted in a poor surface finish.
After machining, samples AC002, AC003, AC012, and AC014 were subjected to polishing using an 80 grit sanding belt. Next, each sample was sequentially rubbed with 100, 120, 180, and 200 grit sand paper. Samples AC002, AC012, and AC014 then were polished on two bench wheel buffers with one being finer than the other. The results were impressive with a mirror-like finish being produced.
Rockwell Hardness testing (ASTM D 785, M Scale, ¼″ diameter ball, 10 kg minimum load and 100 kg maximum load) was performed on several of the samples with the following results being recorded.
The following table displays the heat treating schedule and Rockwell Hardness numbers (M scale, ¼″ diameter ball, 10 kg minimum load, and 100 kg maximum load) for several of the samples.
Important in assessing the foregoing Rockwell Hardness number is the knowledge that 99.5% Al will register approximately 30 on the Rockwell M scale. Values for the inventive samples tested are approximately twice that value.
Next tensile testing (ASTM D638, ISO 527-1) and flexural testing (ASTM D 790, ISO 178) were undertaken on four of the DC current samples (precise number not recorded).
These data represent tensile strengths that are in excess of those of untreated aluminum.
Test samples of the products of Examples 1-3 product were machined, and subjected to Rockwell C Scale Hardness (highest scale) testing (M Scale (normal measurement scale) using ¼″ diameter ball, 10 kg minor load, and 100 kg maximum 5 load).
Raw Materials: Cans and Plastic
Equipment: 100 pound electric tilt furnace with a steel lid with (2) holes drilled in it;
1) hole in the center for a 1¼″ diameter by 24″ long graphite lance with a 4″ paddle that is turned by an electric motor on top.
2) 1″ hole for charging the furnace with the plastic. Argon was delivered with a ½″ black malleable pipe through the spout horizontally then a 90 degree elbow and nipple that turned down vertically and submerged into the bath.
Once the bath was up to temperature and the lid was sealed with putty, the charging of the plastic began. As charging was done through this small/hot hole in the lid, the chips of plastic would start melting making it hard to push through. One could continue to push plastic through the hole until finally a glob would drop into the bath and smoke would begin to escape from the imperfect putty seal that was on the lid and the holes. Immediately, the electric motor would be turned on to begin mixing and the welder would be hooked up; the DC electrical current would be accomplished by connecting the positive lead to the ½″ black pipe that was delivering the argon and the negative lead to the 1¼″ graphite stirring shaft by a large washer.
Raw Materials: Controlled Press Scrap and Calgon Carbon Talc
Equipment: 1,000 pound static electric furnace with a fireboard lid that was not sealed, a quadzilla (air driven motor with a solid 3″ diameter by 30″ long graphite shaft and a 4″ paddle for stirring only. . . not a degassing lance), and a small rotary degasser. Once the bath was up to temperature, the quadzilla was placed in the bath and the rpms adjusted to form a vortex. Then, pre-weighed charges of carbon were dropped into the vortex while the electrical charge is cycled on and off at one minute intervals. Once the desired percent of carbon was charged, the quadzilla was pulled out and replaced by a degasser, which was ran for approximately (15) minutes. The material was skimmed of any dross and then ladled out into either billet molds or ingot molds.
Raw Materials: Controlled Press Scrap and Calgon Carbon Talc
Equipment: 600 pound gas-fired tilt furnace with an industry standard flux injector and rotary degassing unit.
Starting with a 1280-1325 degree Fahrenheit molten bath of controlled aluminum feedstock, a rotary degasser, equipped with a 3″ diameter by 36″ long hollow graphite lance with a 6″ stirring paddle on the end, and (2) graphite electrodes are also installed through the bottom of the steel frame/lid and insulated with ceramic washers. These leads may be used to connect the direct current for electrically charging the bath. Hooked to the degasser is an air line that operates the rotary air motor that turns the lance and paddle. There is also a flux injector full of calgon carbon talc connected by another hose that is driven by pressurized argon as a delivery system for the carbon down through the hollow lance getting it below the bath.
The flux line is primed with carbon delivery and dropped slowly down into the molten bath. Once the paddle of the lance is submerged, the air motor is started to begin turning it. The rpms of the air motor/submerged paddle are adjusted until a good vortex of molten metal is formed. Once the degasser is set in place the stirring lance and the electrodes are all submerged. Up to this point, the carbon talc is exiting the bath through the argon bubbles. Then the (2) leads are connected and electrically charged with 42 DC volts . . . 225 amps. The process may be controlled automatically by the preprogrammed cycles of the flux injector, which may preferably be calibrated based on the desired percentage of injection.
Aluminum composite was prepared in accordance with the method of the present invention using a carbonaceous material (i.e., powdered carbon), 6061 aluminum, and using the process parameters herein without the use of an inert atmosphere. The aluminum composite prepared in accordance with the method of the present invention was formed by adding 2% carbon to 6061 Aluminum. A comparative melt of 6061 Aluminum with 0% carbon was also prepared. Spectra of the 0% carbon 6061 Aluminum are shown in
The data from the spectra shown in
Samples of these materials were subjected to photomicrographic study which revealed that the carbon is uniformly distributed in the carbon-containing sample.
The photographic study performed on both structures in etched and unetched conditions such that, even after polishing for about 3 hours, no individual phases of carbon could be identified. The same result was obtained when the carbon-containing sample was etched with 1% HF.
The composite was studied with the aid of an electron microscope at magnifications from 500 to 4,500 times.
These results indicate that the carbon is in such a finely divided or dissolved state that particles could not be seen or identified even under magnification of 3000 times.
These photomicrographs demonstrate that an aluminum composite prepared in accordance with the method of the present invention evidences that the added carbon is uniformly finely divided or in solution such that discrete phases of carbon are not visible within the aluminum matrix examined at great magnification (i.e., up to 3000×) . These photomicrographs also reveal that the carbon is substantially uniformly distributed within the aluminum matrix, in a finely divided or solvated form.
Results of Testing P1020 Aluminum Ingots Made in Accordance with the Present Invention: Sections of P1020 Aluminum Ingots with 0% to 8% Carbon Additions
Nine (9) P1020 aluminum ingot sections were submitted for mechanical property and microstructural analysis. The samples were submitted by Aluminastic Corporation (P.O. Box 134, Ironton Ohio 45638) through the Edison Materials Technology Center (EMTEC), and were prepared in accordance with the method of the present invention as described herein.
These samples individually contained varying degrees of carbon additions from 1% to 8% with a 0% control sample. One of the purposes of this testing was to determine why material made in accordance with the present invention might be processed up to 40% faster through an extrusion process and whether a new and unique microstructure had been created. The question also existed as to whether the carbon was in solid solution with the matrix or had become concentrated at the grain boundaries.
TEST PROCEDURE: In all cases not enough material was supplied to machine regulation ASTM Standard E 8 test specimens. Additionally, due to the soft nature of the P1020 aluminum, several samples either fractured or deformed during the machining process. As such, only the 2%, 4%, 6% and 7% samples were prepared sufficiently to provide 0.375-inch diameter straight section tensile samples; i.e., no reduced gage section. These samples were tested on an Instron 3385H Universal Testing System in accordance with ASTM Standard E 8 test procedures. The 0%, 2%, 4%, 6% and 8% samples were sectioned, mounted, polished and etched in accordance with standard metallographic procedures. The microstructures were then analyzed using a Nikon Epiphot 200 Inverted Metallograph with image capture capability. The 0%, 4% and 8% carbon addition samples were analyzed to create dot maps using an Amray 1830 Scanning Electron Microscope (SEM) with Energy Dispersive Spectroscopy (EDS) capable of light element analysis.
TEST RESULTS:
I. Mechanical Property Testing
Carbon Addition UTS (ksi)
Note: UTS=Ultimate Tensile Strength
Published literature identifies the room temperature UTS of “pure” aluminum; i.e., 99.0% and higher, at between 10.2 ksi for 99.6% and 8.7 ksi for 99.8%.
II. Microstructural Analysis
In as-cast aluminum, and due to the ever presence of impurity elements such as iron and silicon, equilibrium phases of aluminum-iron and/or aluminum-iron-silicon typically form. These phases are usually Fe3Al, Fe3SiAl12 or Fe2Si2Al9 or, if solidification is rapid, FeAl6 or MnAl6.2 The equilibrium phases of impurity elements are observed in all the microstructures; however, there seems to be a tremendous increase of such phases in the 8% carbon addition sample. Higher magnification images are provided in
III. Dot Map Analysis
The question of the fate of the carbon still required analysis. Optical Emission Spectroscopy (OES) techniques do not provide useful data since carbon is an impurity in aluminum and usually present in relatively small amounts. Inductively Coupled Plasma (ICP) spectroscopy should be employed to analyze the carbon levels in a given sample, but is beyond the MVMTC scope of work and was not authorized by the customer. Instead, the Scanning Electron Microscope (SEM) with Energy Dispersive Spectroscopy (EDS) was utilized to perform a dot map analysis of the surface of the prepared samples; in this case, the 0%, 4% and 8% samples.
When the electron beam of the SEM is scanned across a sample, it generates x-rays from the atoms in the top two microns of the surface. The energy of each x-ray is characteristic of the atom from which the energy escaped. The EDS system collects the x-rays, sorts them by energy and displays the number of x-rays versus their energy. This data can then be used to produce color dot maps which show each element's distribution across the sample surface in a different color. Dot maps at two different magnifications were generated for the 0%, 4% and 8% samples to identify the presence and location of carbon, silicon, iron, manganese, zinc and aluminum.
These dot maps are presented in
The results showed that the addition of carbon to the P1020 (99.7%) aluminum matrix potentially had a minor beneficial effect on the UTS. The tensile samples that were fabricated did not conform to ASTM Standard E 8 due to the softness of the samples, but the test procedure was run in accordance with E 8. Room temperature UTS of “pure” aluminum; i.e., 99.0% and higher, is reported to be between 10.2 ksi for 99.6% and 8.7 ksi for 99.8%.
It also appeared that a grain structure modification had taken place between the 4% and 6% carbon addition samples in which the microstructure went from being predominately dendritic to one of larger, mostly equiaxed, grains. This could, however, also be the result of unequal solidification rates and/or faster or slower solidification rates.
Dot map analysis of the 0%, 4% and 8% carbon addition samples showed the carbon to be randomly distributed within the aluminum matrix and not concentrated at the grain boundaries.
Aluminum feedstock is comprised of clean extrusion press scrap of a certain grade (6061, 356, etc.) and an amount of carbonaceous material is measured out by percentage of weight depending on what specific outputs in mechanical and or physical characteristics are required. For example, if one desired a two percent mix, one may use the weight of the aluminum charge multiplied by two percent to arrive at the amount of carbonaceous material that would be needed. The carbonaceous material preferably is then measured out into smaller manageable size packages that can be introduced into the process in a controlled manner. For example: Aluminum Charge=1000 lbs.; Carbonaceous Charge=(1000 lbs.×2%)=20 lbs
The aluminum charge is then melted at 1245° F. and skimmed for dross at which point an apparatus is used to create an ion generator to create conditions that allow the carbon atoms to be properly conditioned so that they will bond with the aluminum in a reaction of an ion going into solution. In this case the carbon is going into the aluminum and the carbon is acting as the ion and the aluminum as the solution.
The apparatus may also optionally use a rotary degassing head that is used to mix the bath of material for homogeneous mix of materials while processing. The mild vortex that is created helps also to pull the packages of carbonaceous material under the surface of the melt and helps reduce the loss rate of the materials being introduced.
Each time a pre-measured package of carbonaceous material is added, a charge of about 350 amps of DC current are applied to the ion-generator apparatus for 30 seconds. This process is repeated until the entire carbonaceous charge has been incorporated. The charge of DC current is not limited to run at the 350 amps but experience to date has shown this amount of current to be effective and efficient when applied to two percent mixes. Experience has also shown that using AC instead of DC current will work albeit much less efficiently.
The following represent examples of some of the beneficial results and improvements achieved in materials made in accordance with the present invention.
Materials made in accordance with the present invention were found to achieve a 25-40% increase in production throughput at the extrusion die head.
Materials made in accordance with the method of the present invention, when made using 6061 aluminum, has a significant increase in extrusion throughput as compared to standard 6061 and with a reduction of force to extrude. These types of improvements for industrial processing equate into large increases in efficiencies which means huge savings to the manufacturer. Materials made in accordance with the method of the present invention, when made using 6061 and 6063 aluminum showed a 25-40% increase in throughput extrusion with a 30% reduction of force, as compared to their standard equivalents.
Materials made in accordance with the method of the present invention, when made using 356 aluminum, shows a 30% increase in cast flow rate as compared to standard 356 aluminum.
Materials made in accordance with the method of the present invention also exhibited a slight improvement in metal fluidity under the conditions of a fluidity spiral test using 100% sand facing (i.e. 21 vs. 27 inches).
Materials made in accordance with the method of the present invention, when made using 3005 aluminum, could be extruded at temperatures between 400 and 500 degrees Fahrenheit, and may be extruded from a three inch billet.
Materials made in accordance with the method of the present invention exhibit increased formability and machinability. Materials made in accordance with the method of the present invention, when made using 6061 aluminum, reduced one product application from a 16-66% failure rate to a 0% failure rate due to its increased ductility. In this regard, the resultant material was used to make a 90 degree bend for a HUMVEE vehicle windshield. Twelve billets of the material of the present invention made using 6061 aluminum were extruded at normal parameters and tested. This particular profile had a 16% failure rate with primary aluminum and a 60% failure rate with secondary aluminum. The same part made from a material made in accordance with the method of the present invention and based upon 6061 aluminum had a 0% failure rate.
Materials made in accordance with the method of the present invention exhibit increased corrosion resistance.
Although only several exemplary embodiments of this invention have been described in detail, it will be readily apparent to those skilled in the art that the novel produced waste treatment process, and the apparatus for implementing the process, may be modified from the exact embodiments provided herein, without materially departing from the novel teachings and advantages provided by this invention, and may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Therefore, the disclosures presented herein are to be considered in all respects as illustrative and not restrictive. It will thus be seen that the objects set forth above, including those made apparent from the preceding description, are efficiently attained. Many other embodiments are also feasible to attain advantageous results utilizing the principles disclosed herein. Therefore, it will be understood that the foregoing description of representative embodiments of the invention have been presented only for purposes of illustration and for providing an understanding of the invention, and it is not intended to be exhaustive or restrictive, or to limit the invention only to the precise forms disclosed.
All of the features disclosed in this specification (including any accompanying claims, and the drawing) may be combined in any combination, except combinations where at least some of the features are mutually exclusive. Alternative features serving the same or similar purpose may replace each feature disclosed in this specification (including any accompanying claims, and the drawing), unless expressly stated otherwise. Thus, each feature disclosed is only one example of a generic series of equivalent or similar features. Further, while certain process steps are described for the purpose of enabling the reader to make and use certain water treatment processes shown, such suggestions shall not serve in any way to limit the claims to the exact variation disclosed, and it is to be understood that other variations may be utilized in the practice of our method.
Many variations of the present invention within the scope of the appended claims will be apparent to those skilled in the art once the principles described herein are understood. The intention is to cover all modifications, equivalents, and alternatives falling within the scope and spirit of the invention, as expressed herein above and in any appended claims. The scope of the invention, as described herein and as indicated by any appended claims, is thus intended to include variations from the embodiments provided which are nevertheless described by the broad meaning and range properly afforded to the language of the claims, as explained by and in light of the terms included herein, or the legal equivalents thereof.
Accordingly, many other changes and modifications may be made to the present invention without departing from the spirit thereof. The scope of these and other changes will become apparent from the present disclosure and appended claims.
This application is a continuation of U.S. application Ser. No. 12/807,705, filed Sep. 10, 2010, which is a continuation of U.S. application Ser. No. 11/975,733, filed Oct. 18, 2007, now abandoned, which is a continuation-in-part of application Ser. No. 11/190,791, filed Jul. 26, 2005, now abandoned, which is a continuation-in-part of application Ser. No. 10/292,208, filed on Nov. 12, 2002, now abandoned, which is a continuation-in-part of application Ser. No. 09/799,910, filed on Mar. 6, 2001, now abandoned, which is based on provisional application 60/189,684, filed Mar. 15, 2000, the disclosures of which are expressly incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60189684 | Mar 2000 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12807705 | Sep 2010 | US |
| Child | 13542143 | US | |
| Parent | 11975733 | Oct 2007 | US |
| Child | 12807705 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11190791 | Jul 2005 | US |
| Child | 11975733 | US | |
| Parent | 10292208 | Nov 2002 | US |
| Child | 11190791 | US | |
| Parent | 09799910 | Mar 2001 | US |
| Child | 10292208 | US |
