無電鍍鎳／鍍鋁表面處理之Fe-Mn-Al合金鋼800℃高溫氧化行為研究

Oxidation Behaviors of Fe-Mn-Al Alloys With Electroless Nickel/Aluminizing Coatings at 800℃

本研究選用沃斯田鐵相之Fe-30.6% Mn-5.9% Al-0.9% C (wt%)合金鋼試片，於表面分別披覆無電鍍鎳、鋁與無電鍍鎳／鋁等三種改質層，並在800℃ 靜態空氣氣氛進行1～49小時之氧化試驗。氧化試驗之後的各試片表面改質層與基材之間的微觀結構與相變化亦將做進一步的觀察與探討；本研究發現只披覆無電鍍鎳無法改善試片之抗氧化能力，反而造成性能劣化，不過直接固體滲鋁與先披覆無電鍍鎳再滲鋁試片表面於800℃ 靜態空氣環境中生成保護性的Al2O3 相，使試片之800℃ 氧化增重數值大幅下降，其抗氧化性能明顯獲得提升。先披覆無電鍍鎳再滲鋁試片的表面改質層與基材之間生成尖釘狀析出物，可有效改善表面改質層與基材的附著性。

Austenitic Fe-30.6% Mn-5.9% Al-0.9% C (wt%) alloys were chosen to deposit electroless nickel, aluminum and electroless nickel/aluminum coatings on the surfaces. Oxidation tests at 800℃in static air from 1 to 49 hours were conducted. Cross sectional microstructures and phase transformations of oxidized specimens were investigated. It's found that the oxidation resistance of electroless nickel coated specimens was not sufficient and even worse than the untreated matrix. Aluminum oxide was formed on the surfaces of the aluminized and electroless nickel/aluminization specimens after 800℃ oxidation tests. The weight data of these specimens were reduced tremendously and the oxidation resistances were greatly improved. The adhesion of surface layers was enhanced by the formation of spiky precipitates in the interfaces between matrix and surface layer for the electroless nickel/aluminization specimens.