Plasma nitriding process

Abstract

A plasma nitriding furnace is adopted, and after a cylinder sleeve meeting the dimensional requirements is approved, the cylinder sleeve is cleaned through a cleaning agent or gasoline and aired and then enters the furnace. Vacuum pumping is performed in the furnace, ammonia gas is led into the furnace, the furnace is warmed to 400 DEG C at a speed of no higher than 50 DEG C per hour, heat is preserved for 1 hour, the furnace is slowly warmed to 480 DEG C, heat is preserved for 5 hours, and cooling is performed at a speed of no higher than 50 DEG C per hour, and the cylinder sleeve is discharged when the furnace is cooled to 150 DEG C. The cylinder sleeve having undergone nitriding processing is silver grey, product deformation is extremely small because the plasma nitriding temperature is lower than the gas nitriding temperature, the use requirements can be met without needing follow-up process, and surface quality is good.

Description

technical field [0001] The invention relates to a plasma nitriding process, in particular to a plasma nitriding process for a cast iron cylinder liner. Background technique [0002] The cylinder liner is the core part of the engine and is also a vulnerable part. The failure mode of the cylinder liner is mostly the early wear of the cylinder liner caused by the non-wear resistance of the inner hole. In order to improve the wear resistance of the inner hole, the gas nitriding process is often used to carry out the overall nitriding treatment on the cylinder liner. However, due to the high nitriding temperature and large nitriding deformation of the traditional gas nitriding treatment, it is necessary to reserve a margin to eliminate the deformation of the product through honing machine processing, so that the nitrided layer is also partially removed. Contents of the invention [0003] In order to improve the wear resistance of cylinder liner products and reduce the deformat...

AI Technical Summary

Problems solved by technology

However, due to the high nitriding temperature and large nitriding deformation of the traditional gas nitriding treatment, it is necessary to reserve a margin to eliminate the deformation of the product through honing machine processing, so that the nitriding layer is also partially removed.