Silicon-nitride and metal composite

Claim 2

A composite formed in part from a ceramic substrate of silicon nitride and from a refractory metal substrate, said composite comprising: (i) the ceramic substrate of silicon nitride; (ii) the refractory metal substrate which comprises Mo, Ti and Zr; and (iii) a layer greater than 0.1 mm in thickness consisting essentially of MoSi 2 between the ceramic substrate and refractory metal substrate, said layer bonded to the ceramic substrate by a first reacted sublayer on the order of 0.01 mm in thickness and bonded to the metal substrate by a second reacted sublayer on the order of 0.01 mm in thickness; whereby the composite will remain intact as a composite during thermal cycling up to pressures of 240 MPa and temperatures of 1000° C.

Claim 3

The composite according to claim 1 wherein said metal portion comprises about 0.5% by weight Ti and about 0.08% by weight Zr.

Claim 4

The composite of claim 1 wherein the layer of MoSi 2 is formed from a substrate consisting essentially of MoSi 2 .

Claim 5

A composite comprising: a ceramic substrate of silicon nitride; a refractory metal substrate selected from Mo, W, Ta and their associated alloys; and a layer greater than 0.1 mm in thickness consisting essentially of MoSi 2 between the ceramic substrate and refractory metal substrate; with said layer bonded to the ceramic substrate by a first reacted sublayer on the order of 0.01 mm in thickness and bonded to the metal substrate by a second reacted sublayer on the order of 0.01 mm in thickness, wherein said composite is prepared by: (a) contacting as a bonding agent, the layer of MoSi 2 with a portion of the silicon nitride substrate and with a portion of the refractory metal substrate; (b) heating the layer of MoSi 2 to a temperature of between about 1000° C. to about 1300° C.; and (c) compressing the layer with said portions of said substrates, simultaneously with said heating, such that said compression of the layer is with a pressure of at least 30 MPa.

Claim 6

A composite comprising: a ceramic substrate of silicon nitride; a refractory metal substrate selected from Mo, W, Ta and their associated alloys; and a layer greater than 0.1 mm in thickness consisting essentially of MoSi 2 between the ceramic substrate and refractory metal substrate; with said layer bonded to the ceramic substrate by a first reacted sublayer on the order of 0.01 mm in thickness and bonded to the metal substrate by a second reacted sublayer on the order of 0.01 mm in thickness, wherein said composite is prepared by: (a) contacting as a bonding agent, the layer of MoSi 2 with a portion of the silicon nitride substrate and with a portion of the refractory metal substrate; (b) heating the layer of MoSi 2 to a temperature of between about 1000° C. to about 1300° C.; and (c) compressing the layer with said portions of said substrates, simultaneously with said heating, such that said compression of the layer is with a pressure of at least 30 MPa.

Claim 7

The composite according to claim 4 wherein said unreacted MoSi 2 sublayer is between about 0.2 mm and 0.3 mm in thickness.

Claim 8

The composite of claim 4 wherein the composite will remain intact as a composite during thermal cycling up to pressures of 240 MPa and temperatures of 1000° C.