Silicon carbide-to-metal joint and method of making same

Claim 1

A method of preparing a surface of a silicon carbide article for joining by metal brazing to metal comprising: (a) micro-roughening that surface of the silicon carbide article which is to be brazed; (b) applying catalyst consisting essentially of aqueous PdCl 2 directly to the micro-roughened surface in the absence of pretreatment of said surface with stannous chloride; and (c) electrolessly depositing a thin layer of metal selected from the group consisting of Ni, Cr, Au, Ag and Cu on said catalyst-treated surface.

Claim 2

A method of preparing a surface of a silicon carbide article for joining by metal brazing to metal comprising: (a) micro-roughening that surface of the silicon carbide article which is to be brazed; (b) applying catalyst consisting essentially of aqueous PdCl 2 directly to the micro-roughened surface in the absence of pretreatment of said surface with stannous chloride; and (c) electrolessly depositing a thin layer of metal selected from the group consisting of Ni, Cr, Au, Ag and Cu on said catalyst-treated surface.

Claim 15

The method of 3 wherein the article is washed and dried after application of the Ni layer and thereafter is electroplated to a thickness of about 0.003 inch with a metal selected from the group consisting of Cu, Ag, Au, Pt and brass.

Claim 16

The method of 3 wherein the article is washed and dried after application of the Ni layer and thereafter is electroplated to a thickness of about 0.003 inch with a metal selected from the group consisting of Cu, Ag, Au, Pt and brass.

Claim 17

The method of 3 wherein a thin layer of Cu is electrolessly deposited over the Ni and thereafter Cu is electroplated from an acid bath to a thickness of between about 0.002 and 0.004 inch.

Claim 18

The method of 3 wherein a thin layer of Cu is electrolessly deposited over the Ni and thereafter Cu is electroplated from an acid bath to a thickness of between about 0.002 and 0.004 inch.

Claim 20

A method joining a silicon carbide article to a metal article including the steps of: (a) chemically etching a surface of said silicon carbide article to micro-roughen said surface; (b) applying catalyst consisting essentially of aqueous PdCl 2 directly to said etched surface in the absence of any pretreatment of said surface with stannous chloride; (c) electrolessly applying a thin layer of metal selected from the group consisting of Ni, Cr, Au, Ag, and Cu to said catalyst-treated surface; (d) joining said electrolessly coated surface to said metal article by positioning said electrolessly coated surface proximate said metal article and fusing a brazing metal in the space between the coated surface and the metal article.

Claim 21

A method joining a silicon carbide article to a metal article including the steps of: (a) chemically etching a surface of said silicon carbide article to micro-roughen said surface; (b) applying catalyst consisting essentially of aqueous PdCl 2 directly to said etched surface in the absence of any pretreatment of said surface with stannous chloride; (c) electrolessly applying a thin layer of metal selected from the group consisting of Ni, Cr, Au, Ag, and Cu to said catalyst-treated surface; (d) joining said electrolessly coated surface to said metal article by positioning said electrolessly coated surface proximate said metal article and fusing a brazing metal in the space between the coated surface and the metal article.

Claim 25

The method of preparing a surface of a silicon carbide article for joining by metal brazing comprising the following sequence of steps: (a) preheating said article; (b) immersing said surface which is to be brazed in a molten etchant bath consisting essentially of about equal parts of KOH and KNO 3 for a time sufficient to cause micro-roughening of said surface; (c) removing said article from said molten bath; (d) allowing said article to cool to temperature below the boiling point of water; (e) washing said surface to remove any remaining etchant; (f) drying said surface and without further chemical pretreatment; (g) coating said dried surface with a saturated solution consisting essentially of palladous chloride; (h) allowing said surface to dry; (i) electrolessly depositing a layer of Ni to a thickness of about 0.0005 inch; and (j) washing the electrolessly deposited Ni layer and allowing it to dry.

Claim 26

The method of preparing a surface of a silicon carbide article for joining by metal brazing comprising the following sequence of steps: (a) preheating said article; (b) immersing said surface which is to be brazed in a molten etchant bath consisting essentially of about equal parts of KOH and KNO 3 for a time sufficient to cause micro-roughening of said surface; (c) removing said article from said molten bath; (d) allowing said article to cool to temperature below the boiling point of water; (e) washing said surface to remove any remaining etchant; (f) drying said surface and without further chemical pretreatment; (g) coating said dried surface with a saturated solution consisting essentially of palladous chloride; (h) allowing said surface to dry; (i) electrolessly depositing a layer of Ni to a thickness of about 0.0005 inch; and (j) washing the electrolessly deposited Ni layer and allowing it to dry.