Method for improving bond between transplanted coating and die-casting

Claim 1

A PROCESS FOR UNITING AN ELECTROLYTICALLY DEPOSITED CERMET WITH A DIE-CAST METAL, SAID CERMET BEING COMPOSED OF A MATERIAL SELECTED FROM THE GRUP CONSISTING OF TITANIUM CARBIDE, TUNGSTEN CARBIDE AND ALUMINUM OXIDE, SAID DIE-CAST METAL BEING SELECTED FROM THE GROUP CONSISTING OF ALUMINUM, IRON AND MAGNESIUM, THE PROCESS CONSISTING OF ELECTROPLATING SAID CERMET IN A THICKNESS EARGE OR 0.010-0.040 INCHES, AHD HING A CONTROLLED SURFACE ROUGHNESS AT ONE SIDE, SAID CERMET BEING ELECTROLYTICALLY DEPOSITED WITH A CURRENT DENSITY ABOUT 400 AMPS/FT2 DURING A SUBSTANTIAL PORTION OF THE TIME OF SAID DEPOSITION, AND ELECTROPLATING A UNIFORM DEPOSIT OF COPPER-BASE CONSTITUENTS ONTO SAID ONE SIDE OF SAID CERMET IN A THICKNESS RANGE OF 0.0005-0.002 INCHES TO FORM AN ELECTROLYTIC-METALLURGICAL BONDED ASSEMBLY, AND SYBSQUENTLY DIE-CASTING SAID MOLTEN METAL ABOUT SAID ASSEMBLY WHEREBY THE HEAT OF SAID MOLTEN METAL IS EFFECTIVE TO CREATE AN ALLOY METALLURGICAL BOND

Claim 5

A method of uniting an electrolytically deposited cermet with a cast metallic material, said union being particularly useful in a coated rotor housing of a rotary internal combustion engine, the process comprising: a. defining a conductive mandrel having an outer surface complimentary to the resultant inner surface of the union and having a surface roughness no greater than 12 r.m.s., b. electrolytically depositing a thin coating of a composite particle wear-resistant material on to said mandrel, the current density applied to promote said deposition, being above 400 amps/ft2 during a substantial portion of the time of said deposition, c. electrolytically depositing a coating of a copper-base constituent on to said wear-resistant material having a thickness less than said wear-resistant material, d. casting a molten metallic material about said assembly, the molten material having a coefficient of thermal expansion greater than the thermal expansion of said cermet, and e. stripping said mandrel from said casting and inner coatings to expose the inner surface of said wear-resistant material.

Claim 6

A method of uniting an electrolytically deposited cermet with a cast metallic material, said union being particularly useful in a coated rotor housing of a rotary internal combustion engine, the process comprising: a. defining a conductive mandrel having an outer surface complimentary to the resultant inner surface of the union and having a surface roughness no greater than 12 r.m.s., b. electrolytically depositing a thin coating of a composite particle wear-resistant material on to said mandrel, the current density applied to promote said deposition, being above 400 amps/ft2 during a substantial portion of the time of said deposition, c. electrolytically depositing a coating of a copper-base constituent on to said wear-resistant material having a thickness less than said wear-resistant material, d. casting a molten metallic material about said assembly, the molten material having a coefficient of thermal expansion greater than the thermal expansion of said cermet, and e. stripping said mandrel from said casting and inner coatings to expose the inner surface of said wear-resistant material.