Surface modification of austenitic thermal-spray coatings by low-temperature nitrocarburizing

18th Chemnitz Seminar on Materials Engineering – 18. Werkstofftechnisches Kolloquium

Lindner, T.^1 ; Mehner, T.^1 ; Lampke, T.^1

Materials and Surface Engineering Group, Institute of Materials Science and Engineering, Technische Universität Chemnitz, Chemnitz

D-09125, Germany^1

关键词: Carbon concentrations;    Compressive residual stress;    Corrosive conditions;    Cross-section micrographs;    Glow-discharge optical emission spectroscopy;    Material combination;    Selective enrichment;    Thermal spray coatings;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/118/1/012008/pdf
DOI  :  10.1088/1757-899X/118/1/012008

来源: IOP

【 摘 要 】

Thermal-spray coatings of austenitic materials are mainly used under corrosive conditions. The relatively poor wear resistance strongly limits their use. In comparative studies between nitrocarburized and untreated thermal-spray coatings, the influence of the nitrogen and carbon enrichment on the properties of the coatings and the microstructure was investigated. The cross-section micrograph of the nitrocarburized coating shows the S-phase formation in the surface layer region. The depth profile of the nitrogen and carbon concentration was determined by glow discharge optical emission spectroscopy (GDOS) analysis. A selective enrichment of the surface layer region with nitrogen and carbon by means of thermochemical heat treatment increases the wear resistance. The interstitially dissolved nitrogen and carbon causes the formation of strong compressive residual stresses and high surface hardness. Increases in the service life of existing applications or new material combinations with face-centred cubic friction partners are possible. In the absence of dimensional change, uniform as well as partial nitrogen enrichment of the thermal spray coating is possible. Nitrocarburized coatings demonstrate a significant improvement in adhesive wear resistance and extremely high surface hardness.