Effects of Cr interlayer on mechanical and tribological properties of Cr-Al-Si-N nanocomposite coating

Cr-A1-Si-N coatings were deposited on SUS 304 substrate by a hybrid coating system. A Cr interlayer was introduced between Cr-A1-Si-N coating and SUS 304 substrate to improve the coating adherence. The effects of Cr interlayer on the microhardness, adhesion, and tribological behavior of Cr-A1-Si-N coatings were systematically investigated. The results indicate that the microhardness of the Cr-A1-Si-N coatings gradually deceases with increasing thickness of Cr interlayers. The adhesion between Cr-A1-Si-N and SUS 304 substrate is improved by addition of the Cr interlayers. A peak critical load of-50 N is observed for the coating containing Cr interlayer of 60 nm as compared - 20 N for the coating without Cr interlayer. The thicker Cr interlayers result in reduced critical load values. Moreover, the wear resistance of the Cr-AI-Si-N coatings is greatly enhanced by introducing the Cr interlayer with thickness of 60 nm in spite of the decreased microhardness. The friction coefficient of the coating system is also moderately reduced.

Mechanical,Microstructural and Tribological Properties of Reactive Magnetron Sputtered Cr-Mo-N Films

The Cr-Mo-N films were deposited on high speed steel（HSS） substrates by a DC reactive magnetron sputtering equipment coupled with two horizontal magnetron sources.The effects of substrate negative bias voltage（Vb）,substrate temperature（Ts） and gas flow ratio（R= N2/（N2+ Ar）） on the microstructure,morphology,as well as the mechanical and tribological properties of the Cr-Mo-N films were investigated by virtue of X-ray diffraction（XRD） analysis,X-ray photoelectron spectroscopy（XPS）,field emission scanning electron microscopy（FESEM）,atomic force microscopy（AFM）,nano-indentation test,ball-on-disk tribometer,and Rockwell indenter et al.With increasing Vbto-100 V,the preferred orientation of the films changed from（111） to（200） and their mechanical and tribological properties were improved gradually,too.It was also found that Tsgave a significant effect on mechanical property enhancement.When the Tsreached 300 ℃,the film obtained the highest hardness and effective elastic modulus of approximately 30.1 and 420.5 GPa,respectively and its critical load increased to about 54 N.With increasing R,the phase transformation from body-centered-cubic（bcc） Cr and hexagonal CrMoNxmultiphase to single face-centered-cubic（fcc） solid solution phase was observed.The correlations between values of hardness（H）,effective elastic modulus（E*）,HIE*,H3/E*2,elastic recovery（1/14） and tribological properties of the films were also investigated.The results showed that the elastic recovery played an important role in the tribological behavior.