预氧化处理对MP35N合金高温氧化行为的影响  

Effect of Pre-oxidation Treatment on High Temperature Oxidation Behavior of MP35N Alloy

作　　者：刘鲁 刘亚[1,2] 吴长军[1] 吴昱锋 苏旭平[1,2] LIU Lu;LIU Ya;WU Changjun;WU Yufeng;SU Xuping(Jiangsu Key Laboratory of Materials Surface Science and Technology,Changzhou University,Jiangsu Changzhou 213164,China;Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering,Changzhou University,Jiangsu Changzhou 213164,China)

机构地区：[1]常州大学江苏省材料表面科学与技术重点实验室,江苏常州213164 [2]常州大学江苏省光伏科学与工程协同创新中心,江苏常州213164

出　　处：《表面技术》2024年第2期60-70,共11页Surface Technology

基　　金：国家自然科学基金(52271005,51871030);江苏省教育厅高等学校自然科学研究重大项目(17KJA430001)。

摘　　要：目的 探索并优化合金成分、工艺以获得致密稳定的预氧化膜,提高合金抗氧化能力。方法 利用非自耗真空电弧炉熔炼合金,在真空容器中加热金属及其氧化物粉末获得平衡氧压。通过莱茵装置进行预氧化实验。通过FactSage计算Co-Ni-Cr-Mo-Al-Si体系的合金组织相图及其氧化相图,利用X射线衍射(XRD)和扫描电子显微镜对预氧化的试样进行物相分析。结果 在1000℃、10^(–17)atm氧压下预氧化,未含Si的MP35N合金表面出现Cr_(2)O_(3)氧化物;随着Si添加量的增加,表面氧化物变为(Al,Cr)_(2)O_(3),以Cr_(2)O_(3)为主,内氧化物为Al_(2)O_(3);当Si含量(质量分数)为3%时,内部形成了近乎连续的带状Al_(2)O_(3)氧化膜。在1 000℃、10^(–25) atm氧压下,合金表面形成连续的Al_(2)O_(3)膜;在1 000℃、10^(–17) atm氧压下,Co-Ni-20Cr-10Mo-4Al-1Si合金预氧化后的外氧化膜为Cr_(2)O_(3),内氧化物为Al_(2)O_(3);随着氧压的提高,在空气气氛下合金表面生成尖晶石相氧化物。在1 000℃、10^(–17)atm氧压下预氧化1、5、10h,Co-Ni-20Cr-10Mo-4Al-1Si合金表面外氧化膜为Cr_(2)O_(3),内氧化物为Al_(2)O_(3),随着时间延长至20 h,合金表面形成连续的Al_(2)O_(3)膜。结论 随着Si添加量的增加,Al元素的活度不断升高,从而提高了Al_(2)O_(3)的形成驱动力,提升了Al元素的扩散系数,有更多的Al元素扩散至合金表层,有利于Al元素的选择性氧化。预氧化氧压的降低和氧化时间的延长,有利于保护性外氧化Al_(2)O_(3)膜形成,可有效提高合金的抗高温氧化性能。In order to prepare the pre-oxidation film with good high temperature oxidation resistance,the nonconsumable vacuum arc furnace was used to melt the alloy,and the alloy samples were cut into 10 mm×10 mm×1 mm thin sheets for pre-grinding and polishing after annealing at 1 000 ℃ in the box furnace for 7 days.The Rhine apparatus was used for pre-oxidation experiment.The balanced oxygen pressure was obtained by heating metal and its oxide powder in a vacuum container.The oxygen pressure in the quartz tube was 1.9×10^(–3) Pa,and then heat treatment was conducted in a double temperature tube furnace.The effect of Si element on the activity of Al element was calculated by pandat software.The alloy structure phase diagram and oxidation phase diagram of Co-Ni-Cr-Mo-Al-Si system were calculated by FactSage software.The morphology,chemical composition and element distribution of the oxidation film surface and section of the pre-oxidation sample were characterized and the phase was analyzed by X-ray diffraction and scanning electron microscope.At 1 000 ℃under oxygen pressure of 10^(–17) atm oxygen pressure,Cr_(2)O_(3) oxide appeared on the surface of MP35N alloy without Si.With the increase of Si addition in the alloy,the surface oxide of the alloy became(Al,Cr)_(2)O_(3),mainly composed of Cr_(2)O_(3) oxide,and the internal oxide was Al_(2)O_(3).When the content was 3%,a nearly continuous band-shaped Al_(2)O_(3) oxide film was formed inside.Under the oxygen pressure of 10^(–25) atm,continuous Al_(2)O_(3) film was formed on the alloy surface.Under the oxygen pressure of 10^(–17) atm,the outer oxide film of the Co-Ni-20Cr-10Mo-4Al-1Si alloy after pre-oxidation was Cr_(2)O_(3),and the inner oxide was Al_(2)O_(3).With the increase of oxygen pressure,spinel phase oxides were formed on the surface in the air.After pre-oxidation for 1 h,5 h and 10 h at 1 000 ℃ and 10^(–17) atm oxygen pressure,the external oxide film on the surface of Co-Ni-20Cr-10Mo-4Al-1Si alloy was Cr_(2)O_(3),and the internal oxide was Al_(2)O

关 键 词：MP35N Co-Ni-20Cr合金 预氧化 Al_(2)O_(3)氧化膜 氧化机制 表面改性 

分 类 号：TG156[金属学及工艺—热处理]