Structure and Oxidation Behavior of Zr–Y Modified Silicide Coatings Prepared on an Nb–Ti–Si–Cr Based Ultrahigh Temperature Alloy
Structure and Oxidation Behavior of Zr–Y Modified Silicide Coatings Prepared on an Nb–Ti–Si–Cr Based Ultrahigh Temperature Alloy
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DOI：
10.1007/s11085-014-9519-y
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发表时间：
2015-04
影响因子：
2.2
通讯作者：
Xuan Li;Xiping Guo;Yan-qiang Qiao
中科院分区：
文献类型：
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作者：
Xuan Li;Xiping Guo;Yan-qiang Qiao
以Nb-Ti-Si-Cr系超高温合金为基材，采用包埋渗碳工艺制备了ZR-Y改性硅化物涂层。研究了复合体系中锆粉含量和共沉积温度对涂层组织结构的影响。在1250℃下用不同含量的锆粉包覆的涂层具有相似的结构，主要由较厚的(Nb，X)Si2(X代表钛、铬和Hf元素)外层、较薄的(Ti，Nb)5Si4中间层和1-2微米厚的(Nb，X)5Si3内层组成。随着包装液中锆粉含量的增加，涂层厚度显著减小。在1,150℃和1,200℃下制备的涂层与在1,250℃下制备的涂层具有相似的结构，但当共沉积温度提高到1,300℃和1,350℃时，除了上述三层外，还形成了(Ti，Nb)5Si3最外层。在1,250℃空气中，Zr-Y改性硅化物涂层可以保护基合金至少100小时不被氧化。Zr-Y改性硅化物涂层良好的抗氧化性能归因于形成了由二氧化硅和二氧化钛组成的致密氧化膜。
Zr–Y modified silicide coatings have been prepared on an Nb–Ti–Si–Cr based ultrahigh temperature alloy by a pack cementation process. The effects of amount of Zr powder in the pack mixture and co-deposition temperature on the coating structure were assessed. The coatings prepared at 1,250 °C with different amounts of Zr powders in the pack mixture have similar structures, mainly consisting of a thick (Nb,X)Si2(Xrepresents Ti, Cr and Hf elements) outer layer, a thin (Ti,Nb)5Si4middle layer and a 1–2 µm thick (Nb,X)5Si3inner layer. The increased amount of Zr powders in the pack mixtures led to a significant decrease in the coating thickness. The coatings prepared at 1,150 and 1,200 °C have similar structures to that prepared at 1,250 °C. However, when the co-deposition temperature increases to 1,300 and 1,350 °C, a (Ti,Nb)5Si3outermost layer formed in addition to the three layers mentioned above. The Zr–Y modified silicide coating can protect the base alloy from oxidation at least for 100 h at 1,250 °C in air. The good oxidation resistance of the Zr–Y modified silicide coating is attributed to the formation of a dense scale consisting of SiO2and TiO2.