Si-Yb_(2)O_(3)/Yb_(2)Si_(2)O_(7)/Yb_(2)SiO_(5) EBC涂层组织结构及熔盐腐蚀行为研究  

Microstructure and Resistance to Molten Salt Corrosion of Si-Yb_(2)O_3/Yb_(2)Si_(2)O_(7)/Yb_(2)SiO_(5) EBC

作　　者：王达望 李其连 张乐[1,3] 李淑青 杨伟华 WANG Da-wang;LI Qi-lian;ZHANG Le;LI Shu-qing;YANG Wei-hua(AVIC Manufacturing Technology Institute,Beijing 100024,China;Science and Technology on Power Beam Processes Laboratory,Beijing 100024,China;Aviation Key Laboratory of Science and Technology on Advanced Surface Engineering,Beijing 100024,China)

机构地区：[1]中国航空制造技术研究院,北京100024 [2]高能束流加工技术重点实验室,北京100024 [3]先进表面工程技术航空科技重点实验室,北京100024

出　　处：《表面技术》2023年第5期131-139,162,共10页Surface Technology

基　　金：国家科技重大专项(2017-VI-0020-0092)。

摘　　要：目的 研究Si-Yb_(2)O_(3)/Yb_(2)Si_(2)O_(7)/Yb_(2)Si O_(5) 3层EBC涂层的抗熔盐腐蚀性能。方法 采用真空等离子喷涂工艺在试样表面单面制备Si-Yb_(2)O_(3)/Yb_(2)Si_(2)O_(7)/Yb_(2)Si O_(5) 3层结构的EBC涂层,选用尺寸为Ф25 mm、厚度为5 mm的SiC_(f)/SiC复合材料基体试样,在900℃、NaCl(质量分数为50%)+Na_(2)SO_(4)(质量分数为50%)混合盐中进行连续100 h的熔盐腐蚀试验,采用光学显微镜、扫描电镜、X射线衍射仪等观察和测试3层EBC涂层熔盐腐蚀前后的形貌,分析其组织结构以及该EBC涂层在熔盐腐蚀过程中的化学反应机理。结果 经过连续100 h、900℃的熔盐腐蚀,基体SiC_(f)/SiC复合材料被完全腐蚀掉;底层Si和Yb_(2)O_(3)出现了部分缺失、涂层不完整的现象;中间层Yb_(2)Si_(2)O_(7)在熔盐腐蚀后形成了大量孔洞,但依然基本保持了其原有的涂层框架尺寸;面层Yb_(2)Si O_(5)在涂层厚度尺寸上与熔盐腐蚀之前的尺寸基本一致,熔盐腐蚀后结构致密,维持了自身的化学稳定性。结论 SiC_(f)/SiC复合材料本身不具有抗熔盐腐蚀能力,底层Si和Yb_(2)O_(3)涂层的抗熔盐腐蚀性能较差,体系中Yb_(2)Si_(2)O_(7)中间层具有一定的抗熔盐腐蚀性能,而Yb_(2)SiO_(5)面层具有良好的抗熔盐腐蚀性能,因此在Si-Yb_(2)O_(3)/Yb_(2)Si_(2)O_(7)/Yb_(2)Si O_(5) 3层结构EBC涂层体系中,按抗熔盐腐蚀能力由低到高排序为:底层Si和Yb_(2)O_(3)<中间层Yb_(2)Si_(2)O_(7)<面层Yb_(2)Si O_(5),本体系中的EBC涂层具有良好的抗熔盐腐蚀性能。SiC_f/SiC composite materials have high specific strength,high specific modulus and other excellent mechanical properties at high temperature.SiC_f/SiC composites have excellent oxidation resistance due to the reaction with oxygen in the air to form a dense layer of SiO_(2) protective film.However,molten salts from the environment dissolve the SiO_(2) protective film,resulting in rapid corrosion of SiC_f/SiC composites.The most common molten salt impurities in aero-engine combustion chambers,turbines,and tail nozzle environments are molten Na_(2)SO_(4) and NaCl.Environmental barrier coatings(EBCs)are generally used to resist oxidation and corrosion of composite materials by the gas environment.Plasma spraying technology is the most important EBC preparation technology,which has the characteristics of fast deposition rate,high production efficiency,strong adaptability to specimen shape and size,and large controllable range of coating thickness.A three-layer EBC was prepared by vacuum plasma spraying process,the EBC with rare earth Yb_(2)O_(3) doped Si as the bottom layer,Yb_(2)Si_(2)O_(7) as the middle layer,and Yb_(2)SiO_(5) as the surface layer.The three-layer structure EBC was investigated at 900℃.The corrosion behavior of molten salt was researched in an environment mixed with NaCl and Na_(2)SO_(4) at a mass ratio of 1∶1.The Si-Yb_(2)O_(3)/Yb_(2)Si_(2)O_(7)/Yb_(2)SiO_(5) three-layer structure EBC was prepared on one side of the sample surface by vacuum plasma spraying process.Continuous 100 h molten salt corrosion test was carried out in+50wt.%Na_(2)SO_(4) mixed salt.Optical microscope,scanning electron microscope and X-ray diffractometer were used to observe and test the morphology of the three-layer EBC before and after molten salt corrosion,analyze its structure and chemical reaction mechanism in the molten salt corrosion process.After continuous molten salt corrosion at 900℃ for 100 h,the matrix SiC_f/SiC composite was completely corroded;the bottom layer Si and Yb_(2)O_(3) were partially missing and

关 键 词：EBC涂层 真空等离子喷涂 稀土硅酸盐 熔盐腐蚀 高温氧化 

分 类 号：TQ174[化学工程—陶瓷工业]