Patent ID: 8845823
Filing Date: 2014-09-30
Classification: C23C

Abstract:
1. A method of case hardening an article of stainless steel, a nickel alloy, a cobalt alloy, a titanium based material or combinations thereof, the method comprising; providing a heating apparatus having a first heating zone downstream of a second heating zone, the heating apparatus having a gas inlet and a gas outlet for providing a passage of gas through the heating apparatus, heating the article in the first zone of the heating apparatus to a first temperature in a range of 185 to 500° C., heating in the second heating zone of the heating apparatus at least one compound containing nitrogen and carbon, said compound having a single, double, or triple carbon-nitrogen bond, which compound is liquid or solid at a temperature of 25° C. and a pressure of 1 bar, said compound hereinafter called an N/C compound, to a second temperature which is lower than the first temperature, and which is in a range of 135 to 450° C. for providing one or more gaseous species, and establishing a passage of gas using a carrier gas that is non-oxidative to the article for contacting the article with the gaseous species to activate the article, and successively heating the article in the heating apparatus in the presence of the gaseous species to a carburizing, nitriding, or nitrocarburizing temperature which is at least as high as the first temperature and which is below 500° C.