Patent ID: 6328819
Filing Date: 2001-12-11
Classification: C23C

Abstract:
A method for thermal treatment of metallic workpieces, said method including the steps of:a) heating the workpieces in a heat treatment furnace to a first temperature of between 400 and 500.degree. C. in a gas atmosphere comprising only ammonia;b) continuing to heat the workpieces to a second temperature of between 500 and 700.degree. C. in a gas atmosphere comprising ammonia and an added oxidizing agent;c) maintaining the workpieces at said second temperature and in this gas atmosphere of step b) for a period of between 0.1 and 5 hours;d) continuing to maintain the workpieces at said second temperature for a period of between 1 and 100 hours in a gas atmosphere that contains ammonia or that contains ammonia and a carbon-releasing substance; ande) cooling the workpieces to room temperature.