Duplex composite coatings which contain metal-oxide diffusion barrier layer were obtained through low pressure plasma spraying (LPPS) on M17F superalloys. The investigations have been made in the mechanism of metal-oxide diffusion barrier, the effect of vacuum diffusion treatment and post-aluminized treatment on diffusion barrier, the relation of the effectiveness of diffusion barrier with various elements and temperatures, and movement of oxides. LPPS diffusion barrier can't inhibit the diffusion of Al. Post-aluminized treatment can improve the effectiveness of diffusion barrier greatly. The larger the volume fraction of oxides in barrier layer, the greater the effectiveness of diffusion barrier. The diffusion barrier layer inhibits interdiffusion of various elements differently. The effectiveness of inhibiting the diffusion of Co, Cr is greater than that of Al. The effectiveness of diffusion barrier varies with temperature, the higher the temperature, the greater the effectiveness. Aluminizing treatment makes oxides move. It is considered that metal-oxide diffusion barrier can inhibit volume diffusion, but can't inhibit short circuit diffusion. The effectiveness of diffusion barrier is in relation with (1) the volume fraction of oxides in barrier layer, and (2) the ratio of volume diffusion total flux to short circuit diffusion total flux. A model has been established to explain the experiment results.
修改评论