低合金鋼錠矽和鋁含量對其在模擬燃燒氣氛之高溫氧化的影響

Effects of Silicon and Aluminum Contents in a Low Alloy Steel Ingot on High Temperature Oxidation in a Simulated Combustion Atmosphere

本文是研究低合金鋼錠中不同Si（0.5～2%）和Al（0，0.4%）含量對其在1050℃實驗室模擬燃燒氣氛（含CO2 6.55%、水蒸氣1.84%、O2 3.75%、N2 70.86%）3小時之高溫氧化的影響，研究方法包括氧化動力研究、高溫銹皮黏附性試驗、氧化生成物分析。結果示各鋼錠之氧化動力曲線均滿足二次抛物線定律，其氧化速率常數值介於44～124 mg2/cm4‧min，不論有無添加Al，提高Si含量將使FeO+Fe2SiO4 銹層愈緻密或所佔的比例愈多，因此有降低氧化之作用，添加0.4% Al之效應依Si 含量的不同而不同，Si含量為0.5%時，因銹皮／底材界面有FeAl2O4，有降低氧化之作用，Si含量為1%時，因微量的Al+3使FeO p型半導體產生摻雜效應，反使氧化提高。Si含量為1.5%或2%時，添加Al無法發生效應，故氧化量無差異。至於對高溫銹皮黏附性的影響，當Si含量提高至2%之時才能顯示Si使高溫銹皮黏附性微量提高，添加Al對銹皮黏附性之效應則甚微。

This paper is to investigate the effects of Si(0.5-2%) and Al(0, 0.4%) contents in a low alloy steel ingot on the high temperature oxidation in a laboratory simulated flue atmosphere(containing CO2 6.55%, water vapor 18.84%, O2 3.75%, Nz 70.86%) at 1050℃ for 3 hours. Experimental methods include oxidation kinetics study, high temperature scale adherence test, and analysis of oxidation products. The results indicate that the oxidation kinetics of each ingot obeys parabolic rate law with oxidation rate constant in the range 44～124 mg2/cm4‧min. No matter Al is alloyed or not, increasing the Si content increases the compactness or the amount of the FeO+ Fe2SiO4, the oxidation is thus reduced. Effect of alloying 0.4% Al depends on the Si content. With 0.5% Si, it reduces the oxidation due to the protective FeAl2O4 at the scale/ base metal interface. With 1% Si, small amount of Al+3 induces doping effect of the p-type semiconducting FeO scale and promotes the oxidation. With 1.5% or 2% Si, alloying Al can not give significant effect and does not affect the oxidation. High temperature scale adherence test indicates that 2% Si reveals slight increase in scale adherence and Si does not give significant effect below this content. On the other hand, alloying Al does not give significant effect on the adherence.