Wear resistance of electro-brush plated Ni/diamond nanocomposite coatings

Ni/diamond composite coatings were deposited on the 304 stainless steels by using direct current brush electroplating. The micro-structure, surface morphology, hardness, friction and wear process were studied. Results showed that the addition of diamond particles reduced the grain size of the brush electroplating Ni coatings because the diamond particles impeded the Ni grain growth during brush electroplating. Diamond particles uniformly distributed in Ni matrix and there was a good bond between diamond particles and Ni matrix in Ni/ diamond composite coatings without obvious cracks and holes at interface. The microhardness of the coatings gradually increased from 409 to 520 HV from pure Ni to 13.4 vol% diamond content coating. The wear rate showed a decreasing trend with diamond content in coatings. The minimum wear rate reached 2.34 x 10-5 mm3/N-1 m- 1 for 13.4 vol% diamond content coating. Compared with pure Ni coating, the wear trace of Ni/ diamond composite coatings was shallow and broadened. The wear mechanism of Ni/diamond composite coatings involved the abrasive wear, fatigue wear, adhesive wear and cutting of diamond particles.