Microstructure and wear resistance of nano titanium dioxide strengthening hardfacing material

The nanometer TiO2 particles (nano-TiO2) 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-TiO2 addition and hardness, wear resistance of the hardfacing material were also investigated in this article. The nano-TiO2 transforms to Ti3O5 firstly at around 1660 degrees C and then transforms to Ti2O3 and MnTi2O4 at around 600 degrees C and 550 degrees C, respectively. The nano-TiO2 has an obvious effect on grain refinement and the grain size is decreased gradually with the increase of nano-TiO2 . Nano-TiO2 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-TiO2 is 0.6%. Meanwhile, due to grain refinement, the carbides distribute more homogeneously with the addition of nano-TiO2 . However, the particles present network distribution along the grain boundary when nano-TiO2 is 0.8 wt%. Moreover, the hardness of hardfacing alloys was the highest value of 56.4HRC when the content of nano-TiO2 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-TiO2 .