Cyclic heating rapid nitridation catalytic cementation process

Abstract

The invention relates to a circular-heating rapid nitriding catalysis process which comprises the following steps: ammonia gas is injected to discharge air after workpiece is put into a nitriding furnace; the nitriding furnace is heated from room temperature to T1 temperature and T2 temperature with two sections of heat insulation; and then another two section of heating and heat insulation are carried out at T1temeprature and T2 temperature; the ammonia gas resolution ratio is controlled within the range of 18-60 percent, and the nitriding is carried out; a thickening process is carried out by fully utilizing the strong-nitriding high-speed step, the depth of a nitriding layer and the nitriding time according to a plurality of parabolas with different P values; white powders of nitriding catalysis agent containing chlorinated rare-earth elements are put into a steel tube along with the workpiece from the nitriding charge, wherein the nitriding catalysis agent comprises the following components according to percentages by weight of 3-10 percent of chlorinated rear-earth, 5-35 percent of ammonium chloride, 20-50 percent of calcium chloride and 20-55 percent of sodium carbonate; two ends of the steel tube are tightly bound by aluminum silicate fiber or rock wool and are then put into the furnace, and the nitriding catalysis agent can play a nitriding effect during the whole nitriding process. The invention improves the absorption capacity of the surface of the workpiece to active nitrogen atoms, accelerates the nitriding speed of the nitrogen atoms, shortens the nitriding insulation time by more than 44.4 percent, saves the electrical energy by more than 32 percent and shortens the production period by more than 32.7 percent.

Description

technical field

[0001] The invention relates to a heat treatment process, in particular to a cycle heating rapid nitriding and infiltration process in a periodic nitriding (nitriding) furnace. Background technique

[0002] At present, nitriding is a chemical heat treatment that infiltrates active nitrogen atoms into the surface of the workpiece by heating. The required compound layer is formed on the surface of the workpiece through nitriding treatment, thereby improving the surface performance of the workpiece. In addition to obtaining better wear resistance, fatigue resistance, red hardness and seizure resistance, it can also obtain higher corrosion resistance; at the same time The deformation of the workpiece is small, and the core has good toughness. However, the nitriding process takes the longest time in heat treatment, consumes the most power, and consumes a lot of ammonia. Conventional nitriding needs to place the workpiece to be nitrided in a special nitriding fur...

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