The Effect of Silicon Content on the High Temperature Oxidation Behavior of Si-containing Steel

• Main Authors: Yu-Ling Yang, 楊毓玲
• Other Authors: Wen-Ta Tsai
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/92764816638956833769

碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 94 === Effect of silicon content on the oxidation rate and scale formation of Si-containing steel was investigated. The silicon content in the steels was between 0.01 to 1.91 wt.%. Thermal-gravimetric analysis was carried out to measure the weight change of steels oxidized in the temperature range of 800℃~1000℃ in air atmosphere. In addition, tube furnace was employed to perform the oxidation test. The crystal structures of the oxides formed on steel were analyzed by XRD, and the microstructure and chemical compositions were examined and identified by SEM and EDS. The result showed that the oxidation rate and scale thickness was decreased as the silicon content increased. The oxides formed on carbon steel (S00) and S05 steel were Fe2O3/Fe3O4/Fe1-xO. Banded-oxide scale was also observed in S05 steel. The scale with double-layer structure was observed in steel, consisting of an outer layer of Fe2O3 and an inner layer of SiO2. Both Fe3O4and Fe1-xO were not identified in S11 steel. A very thin layer of scale was formed on S19 steel at temperature below 1000℃. The scale consisted of Al2O3-rich passive film formed between the steel substrate and the outer Fe2O3. Nodular oxide was also found on the surface of S19 steel. The local breakdown of the oxide was responsible for oxide nodule formation. Oxidation tests in horizontal tube furnace were also conducted at 1200℃. The results showed that the oxidation rate increased with increasing Si content in the steel, in contrast to that found below 1000℃. The formation of liquid phase fayalite (Fe2SiO4) was responsible for the high oxidation rate in high Si-containing steels.