Microstructure and wear behaviour of pulse electrodeposited Ni-CNT composite coatings

Owing to excellent mechanical properties, such as high strength, high elastic modulus and large elastic as well as fracture strain, carbon nanotubes (CNTs) are attracting significant interests as reinforcements in metallic coatings. In the present investigation, CNT reinforced nickel composite coatings were deposited on a stainless steel substrate using pulse electrodeposition process employing a nickel Watts bath. The presence of CNTs in the composite coating prohibited the columnar growth of the nickel grains resulting in random/weak texture and smaller thickness of the composite coatings. The Ni-CNT composite coatings exhibited significantly improved microhardness (580 +/- 15 HV) compared to pure nickel coatings (320 +/- 15 HV). The ball-on-disc wear testing data indicated that the reinforcement of CNTs significantly improved wear resistance of the composite coatings compared to pure nickel coatings.