Improvement of Environmental Resistance by Nano-Scale Surface Modification

The corrosion resistance is obtained by The surface oxide filmprevents the substrate alloys from harmful effect of the environment. Thereforethe corrosion resistance is highly depends on the结构of the surface film. In the presentwork, we developed some processes，nano结构的surface film to obtain more protective films. the summaries are(1) Chemical modification of passive film on stainless steels；the combination of active dissolution and passivation derived selective Fe dissolution and Crenrichment in the passive film to show excellent corrosion resistance. Especially, a process in F？ions containing bath was developed. (2) Ion implantation on stainless steels；Cr implantation derived the passive film with concentrated Cr. However，前和后treatments to modify the nano structure of the substrate were(3) Modification of passive film by Modification of passive film by necessary in order to obtain high corrosion resistance.ultra-violet light irradiation；passive film of Fe-Cr and stainless steels were modified by uv light irradiation to obtain muchhigher corrosion resistance. The photo quantum effect enriched The Cr in The passive film. (4)high corrosion resistance thin alloys film with ordered structure by ion beamsputtering;very high corrosion resistant stainless steel films obtained with chemical composition ofordinary grade,but with highly homogeneous structure. The effects of additives also discussed. (5) Nanomodification of the oxide scales formed on TiAl by very small Zr addition；the high temperature corrosion resistance of TiAl was improved by 0.2% Zr addition to TiAl. Zraddition was proved to modify the Al D22 D2O D23 D2 scale thinner and more homogeneous. the Zraddition changed the nano结构的scales to reduce diffusion of oxygen inward。

The corrosion resistance is obtained by the surface oxide film, which prevents the substrate alloys from harmful effect of the environment. Therefore, the corrosion resistance is highly depends on the structure of the surface film. In the present work, we developed some processes, which modify nano structure of the surface film to obtain more protective films. The summaries are described below. (1) Chemical modification of passive film on stainless steels; the combination of active dissolution and passivation derived selective Fe dissolution and Cr enrichment in the passive film to show excellent corrosion resistance. Especially, a process in F? ions containing bath was developed. (2) Ion implantation on stainless steels; Cr implantation derived the passive film with concentrated Cr. However, it was proved that pre and post treatments to modify the nano structure of the substrate were necessary in order to obtain high corrosion resistance. (3) Modification of passive film by ultra-violet light irradiation; passive film of Fe-Cr and stainless steels were modified by uv light irradiation to obtain much higher corrosion resistance. The photo quantum effect enriched the Cr in the passive film. (4) Formation of high corrosion resistance thin alloys film with ordered structure by ion beam sputtering; very high corrosion resistant stainless steel films were obtained with chemical composition of ordinary grade, but with highly homogeneous structure. The effects of additives were also discussed. (5) Nano modification of the oxide scales formed on TiAl by very small Zr addition; the high temperature corrosion resistance of TiAl was improved by 0.2% Zr addition to TiAl. Zr addition was proved to modify the AlィイD22ィエD2OィイD23ィエD2 scale thinner and more homogeneous. The Zr addition changed the nano structure of scales to reduce diffusion of oxygen inward.