本計畫研究以雷射表面被覆處理方法在碳鋼表面製作超不銹鋼層，以提高其耐蝕性質；並探討其耐蝕性質與表面組成、構造之關係。研究結果得知：含氮之超不銹鋼表面層可以混合金屬粉末添加適量Si3N4經雷射表面被覆處理而製得。超不銹鋼層在3.5wt％ NaCl(pH4)或0.1M H2SO4溶液中之極化曲線顯示：合金層中含氮可以大幅提高其鈍化電位；鈍化區之電流密度隨氮及鉻含量增加而大幅降低。含氮含矽合金層中添加鉬有助於其鈍化及再純化。開路電位下之交流阻抗頻譜測試結果顯示：合金層中含氮含矽提高其鈍化膜阻抗；鈍化膜阻抗值隨氮及鉻含量增加而大幅增加；含氮含矽合金層中添加鎳或添加鉬提高其鈍化膜阻抗。合金層電化學交流阻抗頻譜測試後經表面分析及溶液分析等結果得知：氮傾向促進鐵元素優先溶解，使合金層表面富含鉻、鉬；合金層表面存在氨、氮化鉻及氧化矽均可能改善其耐蝕性質。

Laser surface cladding was used to introduce super stainless steel layers on carbon steel to improve its corrosion resistance. The chemical composition, the resulting microstructure and the corrosion behavior in connection with the oxide films of the alloyed layers were analyzed in this investigation. Laser surface cladded nitrogen-containing super stainless steel layers on carbon steel could be produced successfully with preplaced mixed Fe-Cr--(Ni-Mn-Mo)-Si3N4 powders. Nitrogen alloying as a result of Si3N4 decomposition occurs during laser irradiation. The laser cladded super stainless steel layers, evaluated by potentiodynamic polarization tests in 3.5% NaCl solution (pH4) or 0.1M H2SO4, exhibited high resistance to pitting corrosion and the passive current densities decreased with increasing the Cr-N content in the surface alloys. Molybdenum additions to nitrogen-containing alloys are beneficial to the development of passivity and repassivation. Passive film resistance, as determined from EIS measurements in 3.5wt% NaCl solution (pH4) at open circuit potentials, increased with increasing the Cr+N content in the alloys. Nickel additions to nitrogen-containing alloys cause an increase in the passive film resistance. Nitrogen and molybdenum co-exist in the alloys show a combined benefit to the passive film resistance. The surfaces of the nitrogen-containing alloys, after EIS measurements, were analyzed by AES and XPS. The results show that nitrogen additions to the laser cladded alloys are responsible for enriching the passive film with Cr and Mo as a result of the tendency of selective dissolution of Fe. Nitrogen in the passive film might exist either in nitride or ammonia, and the presence of SiO2 in the passive film could possibly modify the surface film and improved the resistance of the alloy to dissolution.