Microstructure and Properties of Co-Ni-Cr_3C_2 Nanocomposite Coatings Produced by Jet-Electrodeposition

摘要

Co-Ni-Cr_3C_2 nano-composite coatings at various concentrations of Cr_3C_2 particles were produced by Jet-eletrodeposition. Surface morphology and crystallographic structure of the coatings were investigated by means of SEM and XRD. Mechanical properties of the coatings were determined using Vickers microhardness and friction wear tester. It was found that adding nano-Cr_3C_2 concentration in electroplating bath weakens the abnormal co-deposition to a certain extent and decreases the deposition amount of co. The increase of the content of nano-Cr_3C_2 in the bath, the content of nano-Cr_3C_2 in the coating increases, when the content of nanoparticles is 80g/l, the content of nano-chromium carbide in the coating reaches the maximum value of 25.13 wt.%. With the addition of nano-Cr_3C_2 particles, the surface of nanocomposite coating is uneven and presents cauliflower head morphology. When the content of nano-Cr_3C_2 particles is 40g/l, the growth of the coating is the most uniform and compact. The phase structure of Co-Ni/nano-Cr_3C_2 coatings is not changed by the codeposition of nano-Cr_3C_2 particles, but it obviously influences the growth and orientation of crystal planes in composite coatings, especially at high nano-Cr_3C_2 particles content. Maximum microhardness was observed to be 595 Hv for Co-Ni-40g/L Cr_3C_2 coating and its wear resistance is the best at the same time.