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无机材料学报

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铌硅化物基超高温合金Si-Y2O3共渗涂层的组织及其高温抗氧化性能

齐 涛, 郭喜平   

  1. (西北工业大学 凝固技术国家重点实验室, 西安 710072)
  • 收稿日期:2009-03-04 修回日期:2009-04-14 出版日期:2009-11-20 网络出版日期:2010-04-22

Microstructure and High Temperature Oxidation Resistance of Si-Y2O3 Co-deposition Coatings Prepared on Nb-silicide-based Ultrahigh Temperature Alloy by Pack Cementation Process

QI Tao, GUO Xi-Ping   

  1. (State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China)
  • Received:2009-03-04 Revised:2009-04-14 Published:2009-11-20 Online:2010-04-22

PDF (PC)

1500

被引次数

11

摘要： 采用Si-Y2O3包埋共渗工艺在铌硅化物基超高温合金表面制备Y改性的硅化物涂层, 研究其在1250℃的恒温氧化性能. 采用扫描电镜(SEM)、能谱(EDS)与X射线衍射(XRD)分析Si-Y2O3共渗涂层氧化前后的物相组成和组织变化. 结果表明：涂层具有明显分层的结构, 由外至内依次为(Nb,X)Si2(X表示Ti, Hf和Cr)外层和(Nb,X)5Si3过渡层, 在过渡层与基体之间有不连续分布的细小(Cr,Al)2(Nb,Ti)块状沉淀. EDS分析表明, 涂层中的Y分布是不均匀的, (Cr,Al)2(Nb,Ti)相的Y含量为0.94at%左右, 而(Nb,X)Si2和(Nb,X)5Si3相的Y含量为0.46at%～0.57at%. 经1250℃分别氧化5, 10, 20, 50和100h后, Si-Y2O3共渗涂层保持其原始的相组成, 并在其表面形成以TiO2、 SiO2和Cr2O3组成的致密混合氧化膜, 且与基体结合良好.

关键词: 铌硅化物基超高温合金, Si-Y2O3共渗涂层, 涂层结构, 高温抗氧化性能

Abstract: Si-Y2O3 co-deposition coatings on Nb-silicide-based ultrahigh temperature alloy were prepared by pack cementation processes. The co-deposition holding temperatures were 1050℃, 1150℃ and 1250℃, and the holding times were 5, 10, 15 and 20h, respectively. The microstructure and isothermal oxidation resistance of the coatings were studied. The results show that all Si-Y2O3 co-deposition coatings are composed of a (Nb,X)Si2 (X represents Ti, Hf and Cr elements) outer layer and a (Nb,X)5Si3 transitional layer. Some thin discontinuous (Cr,Al)2(Nb,Ti) laves phase precipitates exist between the substrate and (Nb,X)5Si3 transitional layer. EDS analyses reveal that the distribution of Y on the coatings is not uniform. The content of Y in (Nb,X)Si2 and (Nb,X)5Si3 phases is about 0.46at%-0.57at% while that in (Cr,Al)2(Nb,Ti) is about 0.94at%. After oxidation at 1250℃ for 5, 10, 20, 50 and 100h respectively, the retained Si-Y2O3 co-deposition coatings still possess double layers structure with their original constituent phases and combine tightly with both scale and substrate. The dense scale developed on Si-Y2O3 co-deposition coatings during oxidation at 1250℃ is composed of TiO2, SiO2 and Cr2O3. Si-Y2O3 co-deposition coatings possess better oxidation resistance than simple Si deposition coatings.

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