Structure And Properties Of Cr-C Coating On4Cr10Si2Mo Steel

Diesel engine exhaust valve is the key component of power plant, it has crucial influenceto the internal combustion engines performance, life and reliability. However, marine dieselengine exhaust valve is subjected to high mechanical loads and thermal loads during operation,the operating conditions are very harsh.This paper mainly deals with the Cr-C coating on the4Cr10Si2Mo steel surface by thePlasma Immersion Ion Implantation and Deposition (PIIID). Scanning electron microscope(SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and opticalmicroscope were used to analyse the structure, organization and microscopic analysis ofsubstrate samples and test samples. The high temperature oxidation, thermal fatigue and hightemperature wear resistance of the Cr-C coating were studied.The results show that the Cr-C coating hardness is Hv953.20, the number approximateto the hardness of hard chrome plating. PIIID Cr-C coating have good quality, the particleswere uniform and small, the shape of the particles are mainly spherical and rod, this pyknoticCr-C coating has a good bonding force with substrate, after measuring the coating, thethickness is about7.19μm, the main components of coating is Cr7C3. Dynamic polarizationcurves of PIIID Cr-C coating in3.5%NaCl aqueous solution show that: the corrosionresistance of Cr-C coating is higher than that of hard chrome coating and Substrate.After a series of high-temperature experimental results show that: PIIID prepared coatingumder750℃high temperature oxidation resistance is very prominent, this coating has veryslow oxidation rate, thus demonstrating excellent properties of high temperature oxidationresistance; The Cr-C compound coating synthesized by PIIID has very good high temperatureoxidation resistance and high temperature wear properties, the thermal shock resistance is twotimes better than chrome plating coating; After high temperature wear, observing themorphology of the three kind of coating, high temperature wear mechanism was proposed.Comprehensive research has shown that4Cr10Si2Mo steel surface prepared by PIIIDCr-C coating has good high temperature performance.