乔彦强,郭喜平

• 1:西北工业大学凝固技术国家重点实验室

摘要(Abstract)：

采用Si-Cr包埋共渗法在Ti-Nb-Si基高温合金表面制备了Cr改性的硅化物涂层,共渗温度为1250和1300℃,时间为10h。利用SEM,EDS和XRD等检测手段分析了涂层的结构、元素分布及相组成等,并对涂层的形成机理进行了讨论。结果表明:Si-Cr共渗温度为1250℃时,降低渗剂中的催化剂NaF含量会降低Si和Cr的反应扩散速度并且改变了涂层的结构和相组成。催化剂NaF含量为8wt%,涂层外层由(Nb,Ti)Si2及少量(Ti,X)5Si3(X代表Nb,Cr和Hf等元素)组成,中间层由(Ti,X)5Si4组成,过渡层由(Nb,Ti)5Si3组成;降低NaF含量至5wt%,Si-Cr共渗温度仍为1250℃时,涂层外层由(Ti,X)5Si3组成,且有较多孔洞出现,中间层为(Ti,X)5Si4,而过渡层很薄。与渗Si涂层相比,Si-Cr共渗涂层中的裂纹明显减少,但在涂层外层存在较多孔洞且涂层厚度明显减小。提高包埋共渗温度至1300℃时,Cr的反应扩散速度得到提高,且在涂层外层出现了(Nb1.95Cr1.05)Cr2Si3三元相。

关键词(KeyWords)： Ti-Nb-Si基高温合金;包埋渗;Si-Cr共渗;涂层形成机理

Abstract:

Keywords:

基金项目(Foundation): 国家自然科学基金项目(50871087)

作者(Author): 乔彦强,郭喜平

DOI: 10.13289/j.issn.1009-6264.2010.03.020

参考文献(References)：

• [1]Bewlay B P,Jackson M R,Zhao J C,et al.A review of very-high-temperature Nb-silicide-based composites[J].Metall Mater Trans A,2003,34:2043-2052.
• [2]Bouillet C,Ciosmak D,Lallemant M,et al.Oxidation of niobium sheets at high temperature[J].Solid State Ionics,1997,101-103:819-824.
• [3]Geng J,Tsakiropoulos P,Shao G S.Oxidation of Nb-Si-Cr-Al in situ composites with Mo,Ti and Hf additions[J].Materials Science and Engineering A,2006,441:26-38.
• [4]Zelenitsas K,Tsakiropoulos P.Effect of Al,Cr and Ta additions on the oxidation behavior of Nb-Ti-Si in situ composites at800℃[J].Materials Science and Engineering A,2006,416:269-280.
• [5]Ryosuke O S,Masayori I,Katsutoshi O.NbSi2coating on niobium using molten salt[J].Journal of Alloys and Compounds,2002,336(1-2):280-285.
• [6]Guo X P,Zhao L X,Guan P,et al.Oxidation behavior and pack siliconized oxidation-resistant coatings of an Nb-based ultrahigh temperature alloy[J].Materials Science Forum,2007,561-565:371-374.
• [7]田晓东,郭喜平.铌基超高温合金表面包埋Si-Y共渗涂层的显微组织[J].金属学报,2008,44(5):585-588.TIAN Xiao-dong,GUO Xi-ping.Microstructure of Si-Y co-deposition coating prepared on a Nb-based ultrahigh temperature alloy by pack cementation process[J].Acta Metallurgical Sinica,2008,44(5):585-588.
• [8]Xiao L R,Yi D Q,Yin L,et al.Morphology and structure of high temperature MoSi2coating on niobium[J].Transactions of Nonferrous Metals Society of China,2005,15(1):18-22.
• [9]Murakami T,Sasaki S,Ito K.Oxidation behavior and thermal stability of Cr-doped Nb(Si,Al)2and Nb3Si5Al2matrix compacts prepared by spark plasma sintering[J].Intermetallics,2003,11(3):269-278.
• [10]Cockeram B V,Rapp R A.Oxidation-resistant boron-and germanium-doped silicide coatings for refractory metals at high temperature[J].Materials Science and Engineering A,1995,192-193:980-986.
• [11]田晓东,郭喜平.铌基超高温合金表面Si-Al包埋共渗抗氧化涂层的组织形成[J].中国有色金属学报,2008,18(1):7-12.TIAN Xiao-dong,GUO Xi-ping.Structure formation of co-deposition of Si and Al coatings on advanced Nb-based ultrahigh temperature alloy by pack cementation process[J].The Chinese Journal of Nonferrous Metals,2008,18(1):7-12.
• [12]Vilasi M,Francois M,Brequel H,et al.Phase equilibria in the Nb-Fe-Cr-Si system[J].Journal of Alloys and Compounds,1998,269:187-192.
• [13]李明,宋力昕,乐军,等.铌表面固体粉末包埋渗硅研究[J].无机材料学报,2005,20(3):764-768.LI Ming,SONG Li-xin,LE Jun,et al.Microstructure and mechanism of pack siliconizing on Niobium[J].J of Inorganic Materials,2005,20(3):764-768.
• [14]Gaillard-Allemand B,Vilasi M,Belmonte T,et al.Silicide coatings for niobium:mechanisms of chromium and silicon codeposition by pack cementation[J].Materials Science Forum,2001,369-372:727-734.
• [15]孔德谆.化学热处理原理[M].北京:航空工业出版社,1992,216.
• [16]Zhang L T,Wu J S.Thermal expansion and elastic moduli of the silicide based intermetallic alloys Ti5Si3(X)and Nb5Si3[J].Scripta Materialia,1997,38(2):307-313.
• [17]Zhang L,Wu J.Ti5Si3and Ti5Si3-based alloys:alloying behavior,microstructure and mechanical property evaluation[J].Acta Materialia,1998,46(10):3535-3546.

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