摘要:
A ceramic-metal composite that is tough and stiff has been prepared and is comprised of an inert ceramic (e.g., alumina) embedded and dispersed in a matrix comprised of a metal (e.g., aluminum), a reactive ceramic (e.g., boron carbide) and a reactive ceramic-metal reaction product (e.g., AlB2, Al4BC, Al3B48C2, AlB12, Al4C3, AlB24C4 or mixtures thereof) wherein grains of the inert ceramic have an average grain size greater than or equal to the average grain size of grains of the reactive ceramic. The ceramic-metal composite may be prepared by forming a mixture comprised of an inert ceramic powder (e.g., alumina) and a reactive ceramic powder (e.g., boron carbide), the inert ceramic powder having an average particle size equal to or greater than the average particle size of the reactive ceramic powder, forming the mixture into a porous body and consolidating the porous body in the presence of a metal (e.g., aluminum) to form the ceramic-metal composite.
摘要:
A process for preparing complex-shaped, ceramic-metal composite articles, comprising:a) contacting a non-wettable powder that is non-wetting to a metal to be used for infiltration with a shaped ceramic body to form a layer(s) of the non-wettable powder on one or more surface(s) of the shaped ceramic body wherein the shaped ceramic body has a region(s) where there is no layer of the non-wettable powder;b) infiltrating the shaped ceramic body with the metal through the region(s) where there is no layer of the non-wettable powder such that a complex-shaped ceramic-metal composite comprising one or more metal phases and one or more ceramic phases is formed, wherein the article has substantially the net shape of the shaped ceramic body and the undesirable regions of excess metal on the surface and undesirable phases within the complex-shaped ceramic-metal composite article near the surface are located only in the region(s) where there is no layer of the non-wettable powder.A complex-shaped ceramic-metal composite article with undesirable regions of excess metal and undesirable phases on the surface(s) of or within the article only where there is or was no layer of non-wettable powder.The process of the invention allows the preparation of complex-shaped ceramic-metal composite articles with undesirable regions of excess metal and undesirable phases on the surface(s) of or within the article only in the regions where there is or was no layer of non-wettable powder. The process of the invention allows the preparation of a complex-shaped ceramic-metal composite article which requires little or no machining of the surface(s) to achieve a finished article. A complex-shaped ceramic-metal composite article is prepared which contains few undesirable regions of excess metal and undesirable phases.
摘要:
A ceramic-metal composite that is tough and stiff has been prepared and is comprised of an inert ceramic (e.g., alumina) embedded and dispersed in a matrix comprised of a metal (e.g., aluminum), a reactive ceramic (e.g., boron carbide) and a reactive ceramic-metal reaction product (e.g., AlB2, Al4BC, Al3B48C2, AlB12, Al4C3, AlB24C4 or mixtures thereof) wherein grains of the inert ceramic have an average grain size greater than or equal to the average grain size of grains of the reactive ceramic. The ceramic-metal composite may be prepared by forming a mixture comprised of an inert ceramic powder (e.g., alumina) and a reactive ceramic powder (e.g., boron carbide), the inert ceramic powder having an average particle size equal to or greater than the average particle size of the reactive ceramic powder, forming the mixture into a porous body and consolidating the porous body in the presence of a metal (e.g., aluminum) to form the ceramic-metal composite.
摘要:
A process for preparing complex-shaped, ceramic-metal composite articles, comprising: (a) contacting a non-wettable powder that is non-wetting to a metal to be used for infiltration with a shaped ceramic body to form a layer of the non-wettable powder on one or more surfaces of the shaped ceramic body, wherein the shaped ceramic body has a region where there is no layer of the non-wettable powder, and (b) infiltration the shaped ceramic body with the metal through the region or regions where there is no layer of the non-wettable powder, such that a complex-shaped ceramic-metal composite comprising one or more metal phases and one or more ceramic phases is formed, wherein the article has substantially the net shape of the shaped ceramic body and undesirable regions of excess metal on the surface and undesirable phases within the complex-shaped ceramic-metal composite article near the surface are located only in the region or regions where there is no layer of the non-wettable powder. The process of the invention allows the preparation of complex-shaped ceramic-metal composite articles with undesirable regions of excess metal and undesirable phases on the surface(s), of, or within, the article only in the regions where there is, or was, no layer of non-wettable powder. The process of the invention allows the preparation of a complex-shaped ceramic-metal composite article which requires little or no machining of the surface(s) to achieve a finished article. A complex-shaped ceramic-metal composite article is prepared which contains few undesirable regions of excess metal and undesirable phases.
摘要:
Hard disk drive components, such as, sliders, load beams, support arms, actuators, actuator bearings, spacers, clamps, spindles, ball bearings, thrust bearings, journal bearings, base plates, housings, and covers, formed of a multi-phase ceramic-based material. One method of making the hard disk drive components includes (a) forming a porous body of ceramic; (b) infiltrating a liquid into the pores of the ceramic body; (c) solidifying the infiltrated liquid; and (d) machining the metal-infiltrated ceramic body to form the hard disk drive component.
摘要:
A porous mullite composition is made by Forming a mixture of one or more precursor compounds having the elements present in mullite (e.g., clay, alumina, silica) and a property enhancing compound. The property enhancing compound is a compound having an element selected from the group consisting of Mg, Ca, Fe, Na, K, Ce, Pr, Nd, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb, Lu, B, Y, Sc, La and combination thereof. The mixture is shaped and to form a porous green shape which is heated under an atmosphere having a fluorine containing gas to a temperature sufficient to form a mullite composition comprised substantially of acicular mullite grains that are essentially chemically bound.
摘要:
The present invention generally relates to a geopolymer precursor dry mixture, geopolymer precursor package, a process of preparing a geopolymer composition, and a method of providing a geopolymer composition to a geopolymer composition preparation site.
摘要:
The present invention relates to modified geopolymer compositions, geopolymer-coated organic polymer substrates, and methods of manufacturing and articles comprising same.
摘要:
The present invention relates to modified geopolymer compositions, geopolymer-coated organic polymer substrates, and methods of manufacturing and articles comprising same.
摘要:
Porous composites of mullite and cordierite are formed by firing an acicular mullite body in the presence of a magnesium source and a silicon source. In some variations of the process, the magnesium and silicon sources are present when the acicular mullite body is formed. In other variations, the magnesium source and the silicon source are applied to a previously-formed acicular mullite body. Surprisingly, the composites have coefficients of linear thermal expansion that are intermediate to those of mullite and cordierite alone, and have higher fracture strengths than cordierite at a similar porosity. Some of the cordierite forms at grain boundaries and/or points of intersection between mullite needles, rather than merely coating the needles. The presence of magnesium and silicon sources during acicular mullite formation does not significantly affect the ability to produce a highly porous network of mullite needles.