Study of the potential effect of spark plasma sintering on the preparation of complex FGM/laminated WC-based cermet

Abstract

In the present work, the capability of SPS process for the production of a complex composite possessing different forms of materials based on WC-Ni-Ti-CNT FGM/laminated composite is investigated. With regard to the unique properties of SPS in producing and densifying a large number of materials, a complex material was prepared as a sandwich structure based on the reaction among Ti, CNT, Ni and WC in various forms consisting of powders, sheets and nano-tubes. The starting materials were initially placed in the graphite mold in the order of Ni powders, WC-10Ni, CNTs coated Ti sheet, WC-15Ni and Ti sheet from bottom to top. The microstructure study showed that the layer of Ni powders was adequately densified as an integrated layer, the second layer, WC-Ni, was attached to the Ni layer from the bottom and, at the top, it was connected to the highly concentrated WC layer formed as a consequence of Ni consumed by Ti to form NiTi and Ni3Ti compounds. Moreover, the Ti sheets were changed into TiC particles as a result of reaction with WC and CNTs, and the WC-15Ni was placed at the top of this layer by bonding the structure properly; and eventually, the Ti sheet remained at the top of the specimen. The micro-hardness examination of the sample revealed the highest hardness related to the position of Ti-based layer due to the formation of intermetallic compounds and carbides.