连铸结晶器足辊表面抗氧化涂层研究与应用
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摘要
对连铸结晶器足辊表面抗氧化涂层进行了研究。采用激光熔敷技术制备了5种新涂层,其中1号、2号为铁基合金,3号、4号为镍基合金,5号为钴基合金。系统分析了各涂层在不同温度下的抗氧化性能。结果表明:氧化温度在900℃以上时,基材和2号、3号涂层均没有形成保护性Cr_2O_3氧化膜,抗氧化性能不足,出现氧化皮和局部剥落。氧化温度在650～1 000℃时,1号、5号涂层表面都生成了连续的Cr_2O_3氧化膜,未发现剥落现象。900℃时,1号、5号涂层的抗氧化性能分别是基材的66和67倍; 1 000℃时,1号、5号涂层的抗氧化性能分别是基材的108和130倍。在650～900℃时,4号涂层表面主要生成连续的Cr_2O_3氧化膜;900℃以上时,生成连续Al_2O_3氧化膜。1 000℃时,4号涂层的抗氧化性能是基材的397倍。采用4号涂层材料制作足辊样件,上机测试表明,其过钢量是基材的10倍以上,使用寿命提高6倍以上。因此,4号涂层材料可以有效延长足辊使用寿命,减少足辊维修次数,节约成本。
Several oxidation-resistant coatings on the surface of foot roller for continuous casting crystallizer were researched. Five kinds of new coating materials were prepared by laser cladding technology,among which No. 1 and No. 2 were iron-base alloys,No. 3 and No. 4 were nickel-base alloys,No. 5 was a cobalt base alloy. The oxidation resistance of these coatings at different temperatures was systematically analyzed. The result showed that when the oxidation temperature was above 900 ℃,no protective Cr_2O_3 oxide film was formed on the base material and coatings No. 2 and No. 3,their oxidation resistance was insufficient,leading to the partial exfoliation of oxide scales. When the oxidation temperature ranging from 650 ℃ to 1 000 ℃,a continuous Cr_2O_3 oxide film was formed on the surface of coatings No. 1 and No. 5,and no exfoliation occurred. The oxidation resistance of coatings No. 1 and No. 5 was 66 and 67 times that of the base material at 900℃,respectively,and was 108 and 130 times that of the base material at 1 000 ℃,respectively. The surface of coating No. 4 mainly formed a continuous Cr_2O_3 oxidation film at temperatures from 650 ℃to 900 ℃,while formed a continuous Al_2O_3 oxidation scale at temperatures above 900 ℃. The oxidation resistance of coating No. 4 was 397 times that of the base material at 1 000 ℃. The coating No. 4 was used to make the sample of foot roller,the online application testing revealed that its amount of steel passed was more than 10 times that of the base material,and the service life increasedby a factor of over 7. Therefore,the coating No. 4 can effectively prolong the service life of foot roller in application,reduce the number of foot rolls maintenance,and save cost.
Several oxidation-resistant coatings on the surface of foot roller for continuous casting crystallizer were researched. Five kinds of new coating materials were prepared by laser cladding technology,among which No. 1 and No. 2 were iron-base alloys,No. 3 and No. 4 were nickel-base alloys,No. 5 was a cobalt base alloy. The oxidation resistance of these coatings at different temperatures was systematically analyzed. The result showed that when the oxidation temperature was above 900 ℃,no protective Cr_2O_3 oxide film was formed on the base material and coatings No. 2 and No. 3,their oxidation resistance was insufficient,leading to the partial exfoliation of oxide scales. When the oxidation temperature ranging from 650 ℃ to 1 000 ℃,a continuous Cr_2O_3 oxide film was formed on the surface of coatings No. 1 and No. 5,and no exfoliation occurred. The oxidation resistance of coatings No. 1 and No. 5 was 66 and 67 times that of the base material at 900℃,respectively,and was 108 and 130 times that of the base material at 1 000 ℃,respectively. The surface of coating No. 4 mainly formed a continuous Cr_2O_3 oxidation film at temperatures from 650 ℃to 900 ℃,while formed a continuous Al_2O_3 oxidation scale at temperatures above 900 ℃. The oxidation resistance of coating No. 4 was 397 times that of the base material at 1 000 ℃. The coating No. 4 was used to make the sample of foot roller,the online application testing revealed that its amount of steel passed was more than 10 times that of the base material,and the service life increasedby a factor of over 7. Therefore,the coating No. 4 can effectively prolong the service life of foot roller in application,reduce the number of foot rolls maintenance,and save cost.
引文
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[4]杨正勇.连铸辊堆焊技术的现状浅析[J].焊接,2006,50(10):57-59.
[5]沈凤刚,刘景凤.冶金轧辊堆焊技术综述[J].中国表面工程,2006,19(3):16-17.
[6]LI Q,SONG J X,XIAO C B,et al. High temperature oxidation behavior of a Ni3Al base alloy containing high contents of W and Mo[J]. Aeronautical Materials,2007,27(2):6-12.
[7]CHENG Y,ZHANG H,SONG L W,et al. Effect of Re element on oxidation resistance of Ni3Al-Mo based alloys at 1 150℃[J]. Transactions of Nonferrous Metals Society of China,2012,22(3):510-515.
[8]李铁藩.金属高温氧化与热腐蚀[M].北京:化学工业出版社,2003.