Powder metallurgy processes – Powder metallurgy processes with heating or sintering – Metal and nonmetal in final product
Reexamination Certificate
2000-05-25
2002-03-12
Mai, Ngoclan (Department: 1742)
Powder metallurgy processes
Powder metallurgy processes with heating or sintering
Metal and nonmetal in final product
C036S037000, C075S252000
Reexamination Certificate
active
06355207
ABSTRACT:
TECHNICAL FIELD
This invention relates to enhancing the flow of agglomerates and bound materials utilizing organic materials. This invention also relates to a process for working particulate materials during agglomeration in a unique way.
BACKGROUND OF THE INVENTION
Agglomeration and binding materials is done to prevent the segregation of fine and course materials. Graphite or other alloys or alloy precursors in a fine form enhance dispersion within a greater matrix of ‘iron’ or other principle material or alloys. The particle size distribution is manipulated to attain desired performance under specific conditions. The formulation of agglomerates or filler material entails fabricability and processing considerations in addition to constituency selection.
In thermal, solvent, pressured, or activated polymer processing, the management of inputs during agglomeration or binding is critical to the achievement of a sound composite or agglomerate with out degrading the organic constituent. Insufficient inputs can cause poor bonding, porosity and irregular deposit configuration and segregation. These conditions are precursor to the formation of agglomerates having a greater disparity in compositions. Excess inputs produce dilution, fragmenting, and oxidation of the organic constituent. The effects of insufficient inputs on the sintering of the compacts made with these weak agglomerates or poorly bound materials include greater variation in production, distortion, voids, softening, or embrittlement. The effects of excess inputs during the formation of agglomerates include reduction in the effectiveness of the lubricant or mold release to aid in reduction of particle/particle or agglomerate/agglomerate friction during compaction. Increase in dusting, segregation in handling; and decrease in effectiveness in ejecting the compact from the die are problems that often occur during processing. They occur after pressing of the compact or during slurry filling of the cavities. They are the primary purpose of the mold release or lubricant in the first place.
With the aforementioned defined process, adding the working during processing attains the necessary rounded agglomerates; and enhanced flow characteristics.
The benefits of this greater flow-ability in traditional press and sinter is enhanced production speed, greater consistency in part to part production, as well as decrease in variation seen over time. This consistency is of paramount importance in decreasing the number of bad parts produced in any given manufacturing process using bound or agglomerated materials. Increasing speed of the manufacturing process during compaction and filling of cavities, decreasing capital equipment costs and labors necessary to produce parts also are achieved benefits.
BRIEF SUMMARY OF THE INVENTION
The composition and process of this invention eliminates these problems. In broad terms with particulate solids, adding organic material and working it upon resolidification in a unique way creates improved binding of the particulate solids. The particulate solids are materials such as metal, semi-metal, ceramic, glass, plastic, alloy, composite, agglomerate or other organic rubber. The organic selection should remain solid in handling and may become liquid during compaction. These materials may consist of a liquid, solid, or mixture selected from the group consisting of fatty acids; and amides, bisamides, soaps and salts of fatty acids; waxes, resins, oils, hydrogenated fats and oils, polymers, resins or mold release or friction reducing agents. With lubricity enough to enable ejection of a molded compact, flow, an adequately low molecular weight and formulation to enable clean burn off if desired. With inputs that may include either pressure, solvents, chemical activation of the polymers or resins, or thermal heat; and working so as to enhance the gluing of particulates together and rounding of the agglomerate to provide flowability.
In an example of thermal processing of a sample to be handled at room temperature, the preferred method makes a mix containing all ingredients that are to be used in this binding sequence. I then heat the mix above the melting point of the organic. As the temperature rises above the melting point, so does the materials chance for degradation increase. Keeping it slightly above its melting point for as little time as possible is a good thing for the organic. On the other hand as we raise the temperature and/or time the viscosity increases. This allows a greater wetting of the particulate surfaces and greater and more consistent distribution of the lubricant to be used as a binder. Generally working below the vapor or boiling or the lubricant and above its melting point is desirable. Preferably, the range is less then half the temperature difference between its boiling or vapor point and its melting point. Most preferably, I work as close to the melting point as possible, while still maintaining a liquid state when working and cooling begins to form the agglomerate. The heated material must be worked with a chilling device with the heat transfer potential to bring the mix down below its titer or softening point. This returns the binder to a solid. The motion or work forms rounded or more spherical agglomerates. This enhances the flowability of the agglomerates after cooling. After the chilling step, the mix can be screened to reduce the range of the agglomerates and create an even more consistent flow.
DETAILED DESCRIPTION OF THE INVENTION
In thermal processing, the process step of heating the mix means heating above the melting point of the organic material. The process includes the steps of using heated material so that upon cooling, it freezes and “glues the particles together”. By taking heated material and working it during cooling, the creation of rounded agglomerates is possible. Extending the subsequent heating and cooling to multiple materials with tiered melting points allows for paired or coupled pre-alloys to be distributed within the greater bound mix.
Other methods include the following steps. Multiple binding levels using multiple materials with tiered melting points. Examples used are pre-bound mixes, which will ultimately allow precursors of complex inter-structural alloys to form within the matrix of a component (multi-matrix composites). This allows for paired of coupled pre-alloys to be distributed within a greater bound mix. Using solvents of pressure instead of heating to force the wetting of the lubricant made binder also is possible. In addition, I can use chemical activation of the polymers or resins.
Solvent activation refers to the organic material dissolved in a solvent with the particulate solids. The preferred process includes the steps of using solvents so that upon evaporation of the solvent, it glues the particles together. This process takes materials that have had the organic portion dispersed in a solvent and works them during evaporation of the solvent in such a way as to form rounded agglomerates.
Pressured material refers to either adding or reducing the pressure of an organic material with particulate solids. At atmospheric pressures, this process includes the steps of using pressured material so that it phase changes into a liquid or vapor and re-solidifies upon returning to atmospheric or room pressure “gluing the particles together”. The process also includes taking pressured material and working it during re-solidification or its return to atmospheric or room pressure in such a way that the creation of rounded agglomerates is possible.
Chemically activating the polymers or resins and working the mix also forms rounded agglomerates.
The organic lubricant or binder may consist of a liquid, solid, or mixture selected from the group consisting of fatty acids; and amides, bisamides, soaps and salts of fatty acids; waxes, resins, oils, hydrogenated fats and oils, polymers or mold release or friction reducing agent. With lubricity enough to enable ejection of a molded compact, flow, an adequately low molecular weight and formulation to enable c
Emch, Schaffer, Schaub & Porcello & Co., L.P.A.
Mai Ngoclan
Windfall Products
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