摘要:
In accordance with the invention there is provided a method for manufacturing a reaction bonded silicon carbide body by heating, in a vacuum or an inert atmosphere, to at least the melting temperature of elemental silicon, a porous compact consisting essentially of a substantially uniform mixture of silicon carbide grain and finely divided carbon while said compact is in intimate surface-to-surface contact with a mixture of finely divided elemental silicon and a small amount of finely divided, uniformly distributed carbon, such silicon-carbon mixture preferably also being in the form of a compact. Upon such heating, a portion of the elemental silicon in the silicon-carbon mixture reacts with the carbon therein to form a friable, highly porous matrix of silicon carbide which functions to guide the flow of the remaining elemental silicon into the porous silicon carbide-carbon compact where it reacts with the carbon therein to form additional silicon carbide thereby to convert the compact to a reaction bonded silicon carbide body.
摘要:
A method for manufacturing heat-resistant reinforced composite materials having a fibrous structure which comprises mixing 99.8 to 90 percent by weight of a first component selected from the group consisting of the nitrides or carbides of aluminum, silicon and boron and mixtures thereof and 0.2 to 10 percent by weight of a second component selected from the group consisting of the rare earth oxides and mixtures thereof, molding the mixture into a desired shape, and sintering the molded mass to create a fibrous structure therein, said first component being 0.2 to 3.0 microns in average particle size, and said second component being 0.1 to 2.0 microns in average particle size.
摘要:
A method of making a polycrystalline sulphide ceramic body by sulphurizing an oxide material in a carbon disulphide atmosphere at a temperature in the range of 400-1000.degree. C and less than the transforming temperature of the sulphide, which transforming temperature represents either the decomposition temperature or the sublimation temperature inherent to the sulphide. One of the advantages of this method is that sulphides can be easily made by the very strong reduction action of carbon disulphide. This application also relates to sulphides made thereby.
摘要:
A polycrystalline silicon nitride body is produced by shaping a particulate mixture of silicon powder and boron into a green body, sintering the body to a density ranging from 60% to 75% of the theoretical density of silicon, said sintered body having pores which are interconnecting and open to the surface of the body, and reacting said sintered body with gaseous nitrogen to convert it to silicon nitride.
摘要:
A method of making a ceramic sintered body, comprising preparing a powder-mixture consisting of 40 to 80 percent by weight of alumina with or without replacing not more than 2 percent by weight by a grain growth inhibitor, 16 to 40 percent by weight of titanium carbide and 4 to 20 percent by weight of metallic titanium, the total being 100 percent by weight, and hot-pressing said mixture. The mixture is not subjected to a calcination in nonoxidizing atmosphere at a temperature of 600*C to 1,000*C as previously proposed by the inventors, but it is directly subjected to hot-press forming at a high temperature under a high pressure.
摘要:
A method is provided for making shaped self-supporting carbon-fiber structure by initially forming a fluid mixture of curable binder and carbon-fiber. The mixture is poured into a mold, and a vacuum is applied to the mold to effect the separation of excess binder. Cure is effected of the residual binder to produce a removable self-supporting shaped carbon-fiber structure.
摘要:
A die steel having high hardenability, high hardness, good toughness and capable of achieving a high polished surface flatness in the air or oil quenched and tempered condition. Such steel is ideally suited as a die steel for lens quality and photo-etching applications. The unique combination of properties is accomplished through a careful balancing of the chemistry, particularly control of those elemental additions which promote segregation. Within the broad chemistry limits, by weight, of carbon 0.3 to 0.8%, and the maximum quantities of manganese 3.0%, phosphorus 0.025%, sulfur 0.025%, silicon 2.0%, nickel 4.0%, cobalt 4.0%, chromium 3.0%, vanadium 1.0%, molybdenum 1.5%, tungsten 1.5%, niobium 0.1%, titanium 0.5%, aluminum 0.10%, optionally boron between 0.0005 and 0.012%, balance iron, the desired polishability can be achieved through adherence to the equation:Surface Roughness (.mu.-inch)=Boron factor [7.07-12.5(% C)+0.72(% Mn)+0.45(% Si)-2.9 (% Ni)+1.13(% Ni).sup.2 +0.87(% Cr)+2.1(% V)+1.12 (% Mo)+0.84(% W)+14(% Nb)], where the calculated Surface Roughness is no greater than 2.65 .mu.-inch. The Boron factor is 1.0 when boron is not present in the above given range, and 1.74 when boron is present.
摘要:
The strength of a reaction sintered silicon nitride body is substantially increased by impregnating the surface of the body with finely divided alumina and then firing the body in a nitrogen atmosphere to a temperature in excess of 1200.degree. C, the reaction being carried out under an appreciable partial pressure of SiO.