利用田口式法則探討表面鋁化改質對FeNiCr合金在800℃乾空氣下的高溫氧化行為研究

Study the Surface-aluminizing Coating by Taguchi Experiments to Enhance High-temperature Oxidation Resistance of FeNiCr alloys at 800℃ in dry air

本研究主要探討FeNiCr滲鋁合金於800℃乾空氣下之高溫氧化行為，藉由田口式法則找出FeNiCr合金經表面鋁化改質之最佳條件，並提升FeNiCr合金的抗氧化能力。由結果得知，FeNiCr合金的最佳表面鋁化參數是在900℃滲鋁9小時，並通入氬氣流量200 cm3/min及使用3%的AlF3作為活化劑。FeNiCr合金經過表面改質處理（以下簡稱FeNiCr-A）會生成以NiAl為主的滲鋁層，且FeNiCr-A合金在800℃的氧化動力學遵守拋物線律；氧化後，FeNiCr基材生成兩層的氧化層，其中，外層以FeCr2O4為主，但有嚴重剝落的情形發生，而內層氧化層則以Cr2O3主；而FeNiCr-A以形成α-Al2O3為主，說明表面改質可以提升FeNiCr合金之高溫抗氧化性能，此乃FeNiCr -A氧化後生成緻密的α-Al2O3，進而使氧化速率明顯地降低。

This study mainly discusses the high-temperature oxidation behavior of aluminized FeNiCr alloy at 800℃ in dry air. The optimal surface aluminization of FeNiCr alloy (named as FeNiCr-A) was explored by Taguchi's rule to improve its oxidation resistance. It was found that the optimal surface aluminizing parameters of the FeNiCr substrate are to head at 900℃ for 9 hours under an Ar flow rate of 200 cm3/min by using 3% AlF3 activator. The surface aluminized layer is mainly composed of NiAl. The oxidation kinetics of the FeNiCr-A alloys followed the parabolic-rate law. Duplex scales formed on FeNiCr consisted of a spalled outer-layer of FeCr2O4 and an inner-layer of Cr2O3, while an exclusive α-Al2O3 layer was detected on the FeNiCr-A alloy. This further indicated that surface aluminizing can effectively improve the oxidation resistance of the FeNiCr alloy.