抄録
The effectiveness of the TiN-plating of ductile iron castings=both as-cast and heat-treated=was examined by dry wear resistance tests. Observations of abraded surfaces and cross sections were conducted to determine the effect of TiN-plating on matrix structure and graphite and on the relationship to wear resistance.
TiN film of hardness of approximately HV 2500 was formed almost uniformly on the matrix and graphite. Wear resistance was much better for TiN-plated castings than for bare castings, and this remained true up to a sliding distance of 1km, regardless of the matrix structure.
The effect of TiN-plating was found to depend on the plastic deformation of the matrix. In the case of annealed castings of low hardness, plastic deformation of the matrix under the TiN film occurred readily, and the membrane exfoliated rapidly due to the formation of fine cracks. In the case of bainitized material of sufficient hardness on the other hand, plastic deformation rarely occurred, with the result that exfaliation appeared less frequently. This also prevented deformation and destruction of the graphite grains, and wear resistance was improved.
