Low-temperature salt bath carbonitriding agent and application of low-temperature salt bath carbonitriding agent to piston rod surface treatment

Abstract

The invention provides a low-temperature salt bath carbonitriding agent and application of the low-temperature salt bath carbonitriding agent to piston rod surface treatment and belongs to the field of piston rods. The carbonitriding agent is low in treatment temperature, the temperature ranges from 450 DEG C to 500 DEG C, time is short and ranges from 40 min to 60 min, a porous layer is thin, the thickness of the porous layer is smaller than or equal to 5 microns, and meanwhile the hardness of a workpiece can be greatly improved. The low-temperature salt bath carbonitriding agent comprises, by weight percent, 35%-38% of urea, 10%-12% of thiourea, 20%-24% of melamine, 10%-12% of potassium hydroxide, 10%-12% of lithium carbonate, 10%-14% of sodium carbonate and 1% of sodium fluoride. The low-temperature salt bath carbonitriding agent can be used for piston rod surface treatment.

Description

technical field [0001] The invention relates to the field of piston rods, in particular to a low-temperature salt bath carbonitriding agent and its application in the surface treatment of piston rods. Background technique [0002] The existing nitriding process for heat treatment of piston rod surface mainly adopts nitriding method, which can be divided into gas nitrocarburizing, liquid nitrocarburizing, solid nitrocarburizing and ion nitriding. Large scale, large environmental pollution, unstable nitriding quality, difficulty in mass production, etc. are gradually eliminated by people. [0003] Gas nitriding is also widely used. The main advantages are easy to control the surface quality, simple operation and wide application, but the production cycle is long, the production efficiency is low, and the corrosion resistance is poor (the neutral salt spray test can reach 96 hours). At present, the domestic gas nitrogen carbon The fatal weakness of co-infiltration method is th...

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Problems solved by technology

[0002] The existing nitriding process for heat treatment of piston rod surface mainly adopts nitriding method, which can be divided into gas nitrocarburizing, liquid nitrocarburizing, solid nitrocarburizing and ion nitriding. Large, environmental pollution, unstable nitriding quality, difficult to form mass production, etc. are gradually eliminated by people

[0003] Gas nitriding is also widely used. The main advantages are easy to control the surface quality, simple operation and wide application, but the production cycle is long, the production efficiency is low, and the corrosion resistance is poor (the neutral salt spray test can reach 96 hours). At present, the domestic gas nitrogen carbon The fatal weakness of co-infiltration method is that the gas composition cannot be strictly controlled, so the quality of the infiltration layer is not stable enough. For ordinary salt bath nitrocarburizing, the corrosion resistance is high, and the neutral salt spray test can reach more than 144 hours, while the low-temperature salt bath nitrocarburizing The co-infiltration neutral salt spray test has reached more than 200 hours, which is beyond the reach of other heat treatments

[0004] Liquid salt bath nitrocarburizing has become the most used treatment method at present. The current existing piston rod surface heat treatment nitriding process uses medium and high temperature salt bath nitriding (580-600°C). This traditional nitriding process will cause the following problems: First, the temperature of the nitride salt bath is high, and the nitride salt bath is very unstable, and the aging is relatively fast. The treated piston rod is easy to form a large number of microporous areas (porous layer) outside the compound, resulting in low surface hardness of the piston rod and resistance to corrosion. Corrosion and wear resistance are poor. Second, the raw materials of the old nitriding salt bath formula contain cyanide, which pollutes the environment, damages the health of workers, and is not conducive to environmental protection.

In addition, the surface of the nitrided piston rod will be corroded and macular after being used for a period of time, which will shorten the service life of the piston rod

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