セラミック溶射材の腐食環境中における疲労強度および破壊機構

概要

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In order to investigate the corrosion fatigue strength and fracture mechanism of ceramic-sprayed steel, rotating bending fatigue tests have been conducted at room temperature in 3% NaCl solution using specimens of medium carbon steel (S45C) with sprayed coating layers of Ni-5%Al (undercoating) and chromia (topcoating). Corrosion fatigue strength of ceramic-sprayed steel was better than that of substrate steel. However, the coated layers contained many pores through which NaCl solution was supplied from the specimen surface to the substrate. Corrosion pits were initiated at the interface between the undercoating and substrate. Subsequently, cracks initiated from the pits and grew into the substrate. Tests were conducted on specimens whose pores were closed by shielding treatment. In this case, NaCl solution was supplied to the substrate through cracks initiated in the topcoating layer. The shielding treatment was effective under low stress levels where fatigue life was more than 10^7 cycles, while it had no effect in improving corrosion fatigue strength under higher stress levels because of the great number of cracks initiated in the topcoating layer.
一般社団法人日本機械学会の論文
1994-02-25