| 摘要 |
PROBLEM TO BE SOLVED: To propose a nitriding method capable of always giving a desired nitrogen concentration to different types of workpieces with the same control system. SOLUTION: The nitriding method comprises the steps of: previously determining the correlation which is held between the ammonia gas partial pressure in a nitriding atmosphere and the nitrogen concentration of a workpiece placed in the atmosphere and depends on the temperature of the atmosphere; measuring the ammonia gas partial pressure in the atmosphere in actual nitriding and the actual temperature of the atmosphere; arithmetically computing the potential of the atmosphere to nitride the workpiece (nitriding potential) on the basis of the measured ammonia gas partial pressure value, the measured atmosphere temperature value, and the above correlation; comparing the arithmetically computed nitriding potential value with the set point of the nitrogen concentration of the workpiece; and controlling the quantity of the ammonia gas fed into the atmosphere so that the nitrogen concentration of the workpiece may coincide with the set point. COPYRIGHT: (C)2007,JPO&INPIT
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