Microstructure and Sliding Wear Performance of Plasma-Sprayed TiB2-Ni Coating Deposited from Agglomerated and Sintered Powder

Abstract

This work is aimed at developing a route for the deposition of TiB2-Ni cermet coating. The feedstock was firstly prepared by agglomeration and sintering, which was subsequently subjected to plasma spraying. The microstructures and the phase composition of the powder, as well as the sprayed coating were analyzed by scanning electron microscopy and x-ray diffraction. The microhardness (Hv) and the fracture toughness (KIC) of the coating were evaluated. A sliding wear test was also performed on the sprayed coating by SRV® tribo-tester using GCr15 steel as a counterpart. The results showed that the phase of sprayed TiB2-Ni coatings consisted of TiB2, Ni, and Ni20Ti3B6, whose amount varied depending on the powder calcination temperature and the TiB2 content in the powder. Both the hardness and the fracture toughness of the coating were also changed with different powders. The Ni20Ti3B6 brittle phase was the main factor affecting the fracture toughness of coating, which also had detrimental effect on the sliding wear performance. The 60TiB2-40Ni coating deposited from the powder calcined at 1250 °C had better sliding wear performance as it presented more dense structure, higher TiB2 content and less retained Ni20Ti3B6 phase in the coating.