Microstructure and wear resistance of nano titanium dioxide strengthening hardfacing material

Abstract The nanometer TiO 2 particles (nano-TiO 2 ) was added into the hardfacing materials to study grain refinement, the effect on phase transformation, and the amount, morphology and distribution of precipitation. Moreover, the relationship between nano-TiO 2 addition and hardness, wear resistance of the hardfacing material were also investigated in this article. The nano-TiO 2 transforms to Ti 3 O 5 firstly at around 1660 °C and then transforms to Ti 2 O 3 and MnTi 2 O 4 at around 600 °C and 550 °C, respectively. The nano-TiO 2 has an obvious effect on grain refinement and the grain size is decreased gradually with the increase of nano-TiO 2 . Nano-TiO 2 has no significant influence on the size of MC carbides but change the carbides morphology. Moreover, the content of MC particles reaches to the highest value of 6.8% when the addition of nano-TiO 2 is 0.6%. Meanwhile, due to grain refinement, the carbides distribute more homogeneously with the addition of nano-TiO 2 . However, the particles present network distribution along the grain boundary when nano-TiO 2 is 0.8 wt%. Moreover, the hardness of hardfacing alloys was the highest value of 56.4HRC when the content of nano-TiO 2 is 0.6 wt%. In addition, the wear resistance of the hard facing layer can be improved for the uniform of the microstructure and the increase of carbides after the addition of nano-TiO 2.