Dense TiN-Ni cermets with improved sinterability,microstructure, and mechanical properties using Ni-coated TiN powders

To solve the poor sinterability and wettability between TiN ceramic and pure metal via using coated composite powders, dense TiN-Ni cermets with uniform microstructure and fine grains were developed at a low sintering temperature of 1300℃ in this work. TiN powders were firstly activated in a strong acid solution, in order to achieve a step-like surface; Ni-coated TiN powders showed an uniform and controllable morphology. Two types of TiN-Ni cermets based on conventional milled powders and Ni-coated TiN composite powders were fabricated by spark plasma sintering (SPS), and used for the comparison concerning the sintering behavior, microstructure and related mechanical properties. Results showed that Ni-coated TiN composite powders helped to improve the sinterability between ceramic and metal, which is rather beneficial to obtain dense TiN-Ni cermets with homogeneous microstructure and high mechanical properties. Compared to those of conventional TiN-Ni, the relative density, Rockwell hardness and fracture toughness increased from 84.9% to 96.6%, 80.2 to 84.3, and 10.2 MPa·m^1/2 to 14.7 MPa·m^1/2, with a rather low sintering temperature of 1300 ℃, respectively.