New wear-resistant material: Nano-TiN/TiC/TiNi composite

Near-eqiatomic TiNi alloy has been found to exhibit high resistance to wear, especially to erosion. The high wear resistance of the alloy may largely benefit from its pseudoelasticity. Recent studies demonstrate that the wear resistance of TiNi alloy can be considerably enhanced when hard particles such as TiC were added as a reinforcing phase. It was expected that the wear resistance of such a composite could be further improved if the TiNi matrix can be strengthened with retained pseudoelasticity. Attempt was made to develop such a tribo composite, using nano-TiN powder to strengthen the matrix of the TiC/TiNi composite. The composite was made using a vacuum sintering process. Sliding wear behavior of this material was evaluated. It was demonstrated that the nano-TiN/TiC/TiNi composite exhibited excellent wear resistance, superior to those of the TiC/TiNi composite and WC/NiCrBSi hardfacing overlay. In order to understand the role of the nano-TiN powder, localized mechanical behavior and micro-scale wear of the TiNi matrix with and without nano-TiN powder were investigated using a triboscope. Worn surfaces were examined using SEM to better understand the wear mechanism and to find out clues for further development.