The Effect of Post-Spray Heat Treatment on the Wear-Resistance of the TiC-Fe Coating Fabricated by HVOF Process

摘要

The physical soundness, microhaidness and wear properties ofthe thermally sprayed TiC-Fe wear-resistant coatings have been investigated.Thermally sprayed coatings were fabricated by HVOF and the subsequentheat-treatments were carried out at temperatures ranging from 800deg C to1000deg C in either vacuum or air for 30 minutes. The wear resistance of theas-sprayed TiC-Fe alloy coatings was found to be better than that of Cr_3C_2-NiCr alloy coatings and similar to that of WC-Co coatings. In addition, thewear resistance and hardness of the coating were improved by the followingheat-treatment in vacuum(~10~(-3)torr). The maximum improvement in wearresistance and microhardness was about 20 and 30 percent, respectively by theheat-treatment performed at 900deg C in vacuum, while the heat-treatment inair deteriorated the wear property due to oxidation. It has been revealed, fromTEM and Mossbauer studies, that the improved wear resistance in the heattreated coating was mammy caused by the hardness increase associated withmartensitic transformation. However, no improvement in the wear resistanceof the TiC-Fe coatings heat-treated in air seemed to be caused by the residualstress due to the oxidation of Fe matrix.