Designed fabrication of hard CrCr2O3Cr7C3 nanocomposite coatings for anti-wear application

Nanocrystalline CrCr2O3Cr7C3 composite coatings were fabricated by electrodeposition followed by thermal treatment. The structures of coatings were investigated using high-resolution transmission electron microscopy and X-ray diffraction analysis. The composition, elemental chemical state, mechanical properties and wear resistance of coatings were determined using energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, nanoindentation and oscillating friction-wear testing, respectively. Wear tracks were observed by scanning electron microscopy. The results show that the as-deposited coating exhibits amorphous structure. The subsequent thermal treatment at 600 °C induces the crystallization and the generation of nanoscale Cr2O3 and Cr7C3 particles in the Cr-matrix, which results in the hardness of the coating increasing to 21 GPa with slight increase in elastic modulus. Owing to the compromise between high hardness and low elastic modulus, the obtained CrCr2O3Cr7C3 composite coating exhibits excellent wear resistance.