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  Process and apparatus for hot-forging synthetic ceramicUSPTO Application #: 20080090720Title: Process and apparatus for hot-forging synthetic ceramic Abstract: The embodiments of the invention are directed to a synthetic ceramic comprising pyroxene-containing crystalline phase, a clast, and a glass phase, wherein at least a portion of the synthetic ceramic is plastically deformable in a certain temperature range. Other embodiments of the invention relate to a method of making a synthetic ceramic, comprising heating a green ceramic material to 900-1400° C., to a temperature sufficient to initiate partial melting of at least a portion of the green ceramic material, transferring the heated green ceramic material to a press, pressing the heated green ceramic material in a die at 1,000 to 10,000 psi, and transferring the heated, pressed green ceramic material to a furnace for cooling to form the synthetic ceramic. (end of abstract) Agent: Darby & Darby P.C. - New York, NY, US Inventors: Jerry Warmerdam, Joseph R. Cochran, Ross Guenther, James L. Wood, Robert D. Villwock USPTO Applicaton #: 20080090720 - Class: 501 86 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20080090720. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATIONS [0001]This application is related to U.S. Ser. No. 11/213,218, filed Aug. 25, 2005, entitled "Synthesized Hybrid Rock Composition, Method, and Article Formed by the Method," which is incorporated herein by reference. This application is also related to U.S. Ser. No. 09/596,271, now U.S. Pat. No. 6,547,550, issued on Apr. 15, 2003, entitled "Apparatus for hot vacuum extrusion of ceramics," U.S. Ser. No. 10/382,765, filed Mar. 5, 2003, entitled "Method and apparatus for hot vacuum extrusion of ceramics," all of which are incorporated herein by reference. FIELD OF INVENTION [0002]Embodiments of the invention relate to the field of advanced ceramics, particularly to the composition and manufacture of synthetic ceramic (also referred herein as a "hybrid rock material" or as "manufactured stone") such as ceramic tile of a ceramic composite that is plastically deformable at high temperature, and otherwise strong, with low porosity. BACKGROUND [0003]Uniaxial hot pressing" and "hot isostatic pressing" of ceramics are well-known processing methods for sintering of advanced ceramics. These processes in the field of advanced ceramics might appear to be similar to the present invention, but are actually quite unrelated processes and are described in W. D. Kingery, "Introduction to Ceramics," John Wiley & Sons, New York, 1960, pp. 72-74, 394, and also D. W. Richardson, "Modern Ceramic Engineering," Marcel Dekker, Inc., New York, 1992, pp. 552-564, and also in the Background section of U.S. Pat. No. 6,159,400. A key distinction between hot pressing and the present invention is that hot pressing is conducted at approximately half the absolute melting temperature of the material, meaning it is in essence a solid-phase sintering process at high pressure, typically 6.9 to 34.5 MPa (1 to 5 ksi). Hot pressing also differs from the present invention in that pressure is applied to the material while it is still in a furnace. This requires that the pressing parts and molds be made from a highly heat-resistant material such as graphite. Graphite parts oxidize over time and are highly susceptible to wear, which makes the hot pressing process expensive and only in use for manufacture of high-cost specialized parts. Hot isostatic pressing diverges even further from the present invention, as described in Richardson, pp. 562-564. [0004]The conventional method of forming ceramic tiles also differs from uniaxial hot pressing, hot isostatic pressing, and the present invention. The conventional method includes the steps of shaping and forming a ceramic composition containing ceramic powders, binder, and water, pressing the ceramic composition near room temperature and then firing the ceramic composition at high temperature near atmospheric pressure. The conventional ceramic tiles are rigid, brittle and cured to a permanently set (thermosetting) composition. Thus, the conventional ceramic tiles cannot be recycled by and reformed by heating and melting the ceramic tile like a thermoplastic polymer can be recycled and reformed. The ceramic tiles of this invention overcome the above deficiencies of conventional ceramic tiles. [0005]U.S. Pat. No. 3,989,795 to Thomas McGee, entitled "Method of compressing ceramic refractory bodies," describes "hot forging" of ceramic refractory blocks with low thermal conductivity for use in the bed of a steel-making furnace, and provides a method to reduce wear of the die or mold. McGee's method requires a complicated and expensive apparatus to remove the sides of the mold and avoid friction. Further, the preheated blank (or billet) in McGee's method must be smaller than the mold so that it can be placed inside. This requires the material flow out to engulf the entire space, which means that the material must have higher processing temperature in order to have low enough viscosity. The higher processing temperature is more expensive to operate, and tends to liquefy a greater portion of the starting material, resulting in a weaker final product. SUMMARY OF THE INVENTION [0006]The embodiments of the invention relate to a synthetic ceramic comprising pyroxene-containing crystalline phase, a clast, and a glass phase, wherein at least a portion of the synthetic ceramic is plastically deformable in a certain temperature range. Preferably, the synthetic ceramic is recyclable. Preferably, the clast contains silicon or a silicon-containing compound. Preferably, glass phase is continuous or co-continuous. Preferably, the pyroxene-containing crystalline phase is continuous or discrete. Preferably, the clast comprises remnant clasts of natural origin. Preferably, the glass phase is distributed as a matrix with the clast interspersed therein. Preferably, the glass phase is distributed as a matrix with the pyroxene-containing crystalline phase interspersed therein. Preferably, the pyroxene-containing crystalline phase contains crystals formed from a melt with a mineral composition comprising a mineral selected from the group consisting of wollastonite, plagioclase feldspar, anhydrite, calcium sulfate and combinations thereof. Preferably, the pyroxene contains an element selected from the group consisting of Mg, Ca, Fe, Na, Mn, Al, Ti, Si, O and combinations thereof. Preferably, the pyroxene-containing crystalline phase comprises crystallites having a chemistry consistent with members of the pyroxene group of minerals having the chemistry (Ca,Na,Mg,Fe.sup.2+,Mn,Fe.sup.3+,Al,Ti).sub.2 [(Si,Al).sub.2O.sub.6]. Preferably, the pyroxene-containing crystalline phase comprises crystallites having chemistry consistent with members of the pyroxene group of minerals having the chemistry (Mg,Fe.sup.2+Ca)(Mg,Fe.sup.2+)[Si.sub.2O.sub.6]. Preferably, the pyroxene-containing crystalline phase comprises crystallites having chemistry consistent with members of the pyroxene group of minerals having the chemistry Ca(Mg,Fe)[Si.sub.2O.sub.6]. Preferably, the synthetic ceramic has an open porosity of less than 0.5 percent. Preferably, the synthetic ceramic has a modulus of rupture in the range of about 8,000 to 12,000 psi. Preferably, the synthetic ceramic has water absorption of less than 0.5 percent. Preferably, the synthetic ceramic has a Taber abrasive wear index in the range of 50-400. More preferably, the synthetic ceramic has a breaking strength of greater than 500 lbs. Preferably, the synthetic ceramic is physically deformable in the range of 200-1500.degree. C. More preferably, the synthetic ceramic is physically deformable in the range of 900-1400.degree. C. [0007]Another embodiment relates to a method of making a synthetic ceramic, comprising heating a green ceramic material to 900-1400.degree. C., to a temperature sufficient to initiate partial melting of at least a portion of the green ceramic material, transferring the heated green ceramic material to a press, pressing the heated green ceramic material in a die at 1,000 to 10,000 psi, and transferring the heated, pressed green ceramic material to a furnace for cooling to form the synthetic ceramic. Preferably, the method does not require a heated die. Preferably, the method does not require exposing the green ceramic material, the heated green ceramic material or the heated pressed green ceramic material to vacuum. Preferably, the synthetic ceramic is a ceramic tile. Preferably, the green ceramic material is made by mixing quarry fines with water to form a mixture and extruding the mixture through a die. Preferably, the green ceramic material contains no binder. Preferably, the heating the green ceramic material is to 1000-1200.degree. C. Preferably, the pressing the heated green ceramic material in a die is at 1,600 to 6,000 psi. Preferably, the cooling to form the synthetic ceramic is in the range of 600-1000.degree. C., preferably at about 800.degree. C. BRIEF DESCRIPTION OF THE DRAWINGS [0008]FIG. 1 shows a microscopic view of fine grained angular particles or clasts of a pulverized mineral and rock sediments found in crushed rock quarry fines and mine tailings. The particles seen here are composed of both single mineral grains and multi-mineral rock fragments. [0009]FIG. 2 shows a microscopic view of the fine grained fly-ash material largely composed of spherical-shaped glass beads with a smaller quantity of angular residual quartz. [0010]FIG. 3 shows a microscopic view of the incompletely melted remnants of the fine grained mineral and rock particles of the sedimentary feedstock materials that collectively comprise the "aggregate" phase of the hybrid rock material manufactured from mine tailings. The mineral grains are typically composed of more than one mineral type. In this example at least three mineral types are visible. [0011]FIG. 4 shows a microscopic view of the incompletely melted remnants of quartz and glass bead grains that collectively comprise the "aggregate" phase of the hybrid rock material manufactured from waste fly-ash material. The original spherical particle shape of the fly-ash and angular shape of quartz grains are recognizable. [0012]FIG. 5 shows a microscopic view of the microfabric of the hybrid rock material manufactured from waste fly-ash material. The remnant fly-ash and quartz clasts comprise the aggregate phase; the glass phase formed from the melting of the fly-ash forms the primary cement of the hybrid rock; and the crystallite phase is composed of small crystals of plagioclase, wollastonite, pyroxene, and anhydrite (shown in FIG. 6). [0013]FIG. 6 shows as microscopic view of larger crystallites of newly formed anhydrite in the fly-ash hybrid rock. The anhydrite crystallites often arrange in linear fashion to form pseudo- or faux-marbling textures on the surface of the ceramic tile. [0014]FIG. 7 shows microscopic view of the remnant of an igneous rock fragment (white boundary line) in the hybrid rock material. The rock fragment was originally composed of amphibole and chlorite. The box marked 8 shows the enlargement in FIG. 8. [0015]FIG. 8 shows a microscopic view of crystallites of magnetite that have formed in the area formerly occupied by amphibole while crystallites of pyroxene have replaced areas of a former chlorite mineral grain. [0016]FIG. 9 is a scanning electron micrograph (SEM) of a thin section of the resulting tile. FIG. 9 shows a number of large and elongated pores, which are the darkest structures in the photomicrograph. [0017]FIG. 10 is a scanning electron micrograph (SEM) of a thin section of the resulting hot-forged tile made from Quarry Fines A. FIG. 10 shows only a few small and mostly round pores, which are the darkest structures in the photomicrograph. [0018]FIG. 11 is a scanning electron micrograph (SEM) of a thin section of a hot-forged tile. [0019]FIG. 12 and its subfigures: FIG. 12A shows the preheated tile blank 12 after transferring from a hot furnace to a press, where it is placed entirely within the cavity of a lower die 13. Upper die 11 is lowered and pressure is applied as depicted in FIG. 12B. In FIG. 12C, the upper die 11 is raised and the forged tile 14 is revealed. In FIG. 12D, the forged tile is shown free from both die surfaces, ready for transfer to a cooling furnace. Continue reading... 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