Effects of diamond size on the deposition characteristic and tribological behavior of diamond/Ni60 composite coating prepared by supersonic laser deposition

• The composite coatings produced by Ni-based alloy and diamond were studied.
• The phase transition of diamond was restrained in supersonic laser deposition.
• The cold hardening of Ni60 matrix was analyzed under the impacting of diamond.
• The abrasion mechanisms of diamond/Ni60 composite coatings were discussed.

Supersonic laser deposition (SLD) process, as a hybrid coating technique, which combines the benefits of both cold spray (CS) and laser irradiation, is a relatively new trend in the field of laser processing. The composite powder of Ni60 alloy powder mixed with diamond particles is deposited on medium carbon steel (AISI 1045 steel) substrate. Two sizes of diamond particles are used respectively in the composite coating. The diamond/Ni60 composite coating specimens prepared by SLD process are studied using scanning electron microscope (SEM), energy dispersive spectrum (EDS) and Raman spectra. The microstructures and interface bonding between the particles and Ni60 matrix are examined using indentation test and SEM. The hardness and tribological properties of the composite coatings are evaluated under Vickers indentation test and pin-on-disc wear test, respectively. The results show that the diamond/Ni60 composite coatings without graphitization of diamond exhibit better tribological properties, the smaller size of diamond is better than the larger one in the composite coatings for wear resistance. This research also demonstrates that SLD technique can deposit hard diamond/Ni60 composite on steel substrate successfully, which cannot be achieved via CS technique.

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