Preparation and characterization of plasma sprayed Ni3Al-hBN composite coating

Ni3Al-hBN composite powders were manufactured by spray drying technology, and then plasma sprayed to form the coatings. The influence of hBN addition amount on the flowability and apparent density of the composite powders, as well as the mechanical and tribological properties of the as-sprayed coatings was evaluated. The results indicate that the spherical powders with uniformly distributed compositions are successfully manufactured by spray drying technology. Both the flowability and apparent density of the Ni3Al-hBN powders, as well as the bond strength and hardness of the composite coatings decrease with the increase of hBN content. Addition of hBN less than 10 wt.% reduces the friction coefficient and brittle fracture of the coatings, which is beneficial to improve the tribological properties of the Ni3Al-hBN composite coatings. However, high hBN addition, damaging the bond in the coating, will deteriorate the wear resistance of the coating. The Ni3Al-hBN composite coating containing 10%hBN shows the optimum properties combining strength and hardness with tribological properties. (C) 2010 Elsevier B.V. All rights reserved