钽合金表面硅化物渗层的高温抗氧化性能  

High Temperature Oxidation Resistance of Si-Y Co-Deposition Coating on Tantalum

作　　者：李涌泉[1] 梁国栋 秦春[1] 蒋亮[1] 董福元 李宁 Li Yongquan;Liang Guodong;Qin Chun;Jiang Liang;Dong Fuyuan;Li Ning(School of Material Science&Engineering,Beifang University of Nationalities,Yinchuan 750021,China)

机构地区：[1]北方民族大学材料科学与工程学院,宁夏银川750021

出　　处：《稀有金属》2021年第9期1148-1152,共5页Chinese Journal of Rare Metals

基　　金：中央高校基本科研项目(FWNX42);国家自然科学基金项目(51961003,52161009);宁夏自然科学基金项目(2020AAC02025)资助。

摘　　要：为提高钽合金的高温抗氧化性能,通过1080,1100和1120℃下Si-Y共渗3 h的方法在其表面制备了Y改性的硅化物渗层,采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和能谱仪(EDS)分析了温度对渗层的组织结构和相组成的影响,并对基体和渗层在1100℃下的抗高温氧化性能进行了对比研究。结果表明:不同温度下制备的Si-Y渗层具有相似的结构,渗层与基体之间均为良好的冶金结合,不同温度下制备的渗层均由TaSi_(2)相组成,随共渗温度的升高,渗层的厚度有所增大,但渗层的致密度随温度的升高呈先增大后减小的趋势。高温氧化表明,钽基体在1100℃下氧化20 min后呈灾难性氧化,氧化膜结构疏松、容易剥落,对基体缺乏保护性;而在实验条件下,Si-Y渗层在氧化时形成了致密的SiO_(2)氧化膜,该氧化膜结构连续,与残余渗层之间结合良好,显著地提高了钽基体的抗高温氧化性能。Due to the excellent combination of high melting point,high hardness and maintain strength,tantalum alloys had generally been applied to manufacture a variety of high temperature applications including rocket nozzles and nuclear reactor radiation shields.However,the poor oxidation resistance at elevated temperature had been a major barrier to its practical applications and commercialization.Adding alloying elements such as W,Nb,Hf,V,Al,Y,etc.had been found to be an effective method to improve the oxidation resistance of tantalum alloy,but further alloying usually led to deterioration of its mechanical properties.Thus,coatings had been made to solve the aforementioned problem.Among various coating systems,silicide coatings were employed to improve the surface properties of tantalum alloys by forming a dense,compact and stable SiO_(2) scale,and Y elements,which had positive influences on reducing the grain size,improving the toughness and enlarging the thickness of the coatings was also employed.In this paper,Si-Y coatings were prepared by pack cementation processes,and the pack mixture was composed of 14Si-1Y_(2)O_(3)-7NaF-78Al_(2)O_(3)(%,mass fraction,pure Si,Y_(2)O_(3),powders were used as donor sources,NaF and Al_(2)O_(3) powers were used as activator and filler of the pack mixture,respectively),each kind of the powders was weighed and then mixed by tumbling in a ball mill.After that,burying the tantalum substrates in the pack powders and then sealed in an alumina crucible with Al_(2)O_(3)-based silica sol binder.The sealed crucible was heated in a tube furnace to 1080,1100,1120 ℃ at a rate of 15 ℃·min^(-1),and then holding 3h at the deposition temperature before the crucible were furnace cooled to room temperature.According to service condition and for comparison,the oxidation behaviors of both tantalum alloy substrate and Si-Y coated samples were carried out under air at 1100 ℃ isothermally,the mass changes of the samples with and without a coating were measured using an electronic balance with an accu

关 键 词：钽 Si-Y共渗 渗层结构 高温氧化 

分 类 号：TG174.44[金属学及工艺—金属表面处理]