Abstract A rigid pyrolytic graphite microcomposite material comprising a matrix of pyrolytic graphite containing embedded therein codeposited crystalline silicon carbide comprising aciculae oriented approximately perpendicular to the a-b plane of the crystallite layers of the pyrolytic graphite. The SiC comprises at least about 5 volume percent of the microcomposite material, preferably at least about 10 volume percent. A method for making said microcomposite material comprising pyrolyzing a mixture of methyl trichlorosilane and a hydrocarbon gas at temperatures of about 2800*F to 4000*F, preferably about 3200*F to 3800*F and, thereby codepositing pyrolytic graphite and SiC. A rigid composite pyrolytic graphite article comprising a matrix of the above microcomposite material containing embedded therein at least one reinforcing refractory filament or strand layer. The refractory filament or strand layer comprises a plurality of unidirectional and substantially parallel, laterally spaced, individual, continuous refractory filaments or strands. The microcomposite matrix is nucleated from each of the individual refractory filaments or strands and interconnected to form a continuous matrix phase surrounding and interconnecting the individual filaments or strands comprising the embedded filament or strand layer. A method for making said rigid pyrolytic graphite article comprising winding a continuous, individual, refractory filament or strand around a shaped form and simultaneously pyrolyzing a mixture of methyl trichlorosilane and a hydrocarbon gas onto the filament or strand at about the point of winding contact to nucleate pyrolytic graphite and SiC from the filament or strand, winding additional turns of the filament or strand around the form, each additional turn being spaced from previously wound turns and, as each of the additional turns is wound, simultaneously pyrolyzing the mixture of methyl trichlorosilane and hydrocarbon gas thereon at about the point of winding contact and on the codeposited pyrolytic graphite and SiC nucleated from previously wound turns.
A process for making a composite of pyrolytic graphite containing embedded silicon carbide aciculae in which the longitudinal axes of said aciculae are aligned substantially in the c-direction relative to the a-b plane of the associated pyrolytic graphite crystallite, which process comprises pyrolyzing a mixture of methyl trichlorosilane, an inert gas, and a hydrocarbon gas onto a heated substrate at a temperature of about 2800* F-3800*F. and at a pressure at which silicon carbide aciculae will be formed, the volumetric ratio of inert gas to hydrocarbon gas being at least 86.7 to 13.3 and the relative flow rates of methyl trichlorosilane and hydrocarbon gas being such that the weight percent flow rate of methyl trichlorosilane is about 5 to 75% and the weight percent flow rate of hydrocarbon gas is about 25 to 95%.
Claim 2
Dependent Claim
134 words
A process for making a composite of pyrolytic graphite containing embedded silicon carbide aciculae in which the longitudinal axes of said aciculae are aligned substantially in the c-direction relative to the a-b plane of the associated pyrolytic graphite crystallite, which process comprises pyrolyzing a mixture of methyl trichlorosilane, an inert gas, and a hydrocarbon gas onto a heated substrate at a temperature of about 2800* F-3800*F. and at a pressure at which silicon carbide aciculae will be formed, the volumetric ratio of inert gas to hydrocarbon gas being at least 86.7 to 13.3 and the relative flow rates of methyl trichlorosilane and hydrocarbon gas being such that the weight percent flow rate of methyl trichlorosilane is about 5 to 75% and the weight percent flow rate of hydrocarbon gas is about 25 to 95%.
Claim 3
Dependent Claim
12 words
The process of claim 1 in which the temperature is about 3200*F-3800*F.
Claim 4
Dependent Claim
12 words
THE PROCESS OF CLAIM 1 IN WHICH THE HYDROCARBON GAS IS METHANE.
Claim 5
Dependent Claim
20 words
The process of claim 1 in which the inert gas is a mixture of hydrogen and argon, helium, or nitrogen.
Claim 6
Dependent Claim
29 words
The process of claim 1 in which the methyl trichlorosilane is present in amount sufficient to provide at least about 5% by volume of silicon carbide in said microcomposite.
Claim 7
Dependent Claim
15 words
The process of claim 1 in which the pyrolysis is carried out at atmospheric pressure.