Effects of Cr-Based Interlayers on Tribological Properties of CrWN Coatings

This work investigates the effects of Cr and Cr-CrN transition layer on the wear resistance of CrWN coating and prepares CrWN coating with excellent wear resistance. CrWN coating,Cr-CrWN coating and Cr-CrNCrWN coating are deposited on tungsten carbide substrates using plasma enhanced magnetron sputtering. The surface morphology,mechanical and tribological properties of the coating are analyzed by scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),Nano-indentation,Rockwell hardness tester and friction tester. The coatings are composed of face-centered cubic CrN and W2 N phases. Cr-CrNCrWN coating has the highest adhesion strength of coating substrate,which is HF1 grade. The hardness of CrWN coating is 21.5 GPa. The introduction of Cr transition layer and Cr-CrN transition layer did not significantly affect the hardness and elastic modulus of the coating. However,Cr transition layer and Cr-CrN transition layer can reduce the friction coefficient and improve the wear resistance of the coating. The friction coefficient of the coatings is 0.656 and 0.703,and the wear rate is 1.366×10^-6 mm³/(N·m)and 1.247×10^-6 mm³/(N·m) respectively in stable friction stage. Moreover,no furrows and cracks on the surface and no obvious spalling of the coating are found after wear. Therefore,the introduction of Cr transition layer and Cr-CrN transition layer can improve the adhesion of the coating/substrate and the wear resistance of the coating.