Study of Synthesis of (TiW)CN-Ni High Strength Cermets and the effects of Secondary Carbides on Microstructure and Mechanical Properties

In this research the powders of TiO2, WO3 and graphite were mixed and after milling with WC balls, the reduction procedure was carried out separately under vacuum and nitrogen pressure. After blending the produced powder with Ni and the secondary carbides, (Ti0.93W0.07) C/C0.7N0.3-20 Ni based cermets were obtained through sintering at 1510 °C. To characterize the synthesized materials, XRD analyzer, SEM and EDS, STEM and hardness examiner were used. With the evaluation of core/rim included microstructures, it was observed that the addition of secondary carbide and also nitrogen in the reduction procedure, has a remarkable influence on the size of cermet microstructure. By the addition of nitrogen, the size of (Ti0.93W0.07) C microstructure was decreased about 3 µm. In this investigation it was shown that the increase of Mo2C from 2 to 8%, the amounts of tungsten and molybdenum elements were decreased in the core area. The weight percentages of W and Mo were changed from 20.01 to 19.5 and from 0.14 to 0.08, respectively. Also, in the rims, the weight percent of Mo, was significantly increased from 4.67 to 11.43. Furthermore, with the addition of just 2% Mo2C, the hardness of this composite material increased remarkably.