Improvement of Oxidation Resistance of TiAl Intermetallic Compound by Electrodeposition of Al Using Molten Salt As a Medium

熔盐介质电沉积Al提高TiAl金属间化合物的抗氧化性能

基本信息

批准号：
13650773
负责人：
HARA Motoi
金额：
$ 2.05万
依托单位：
Akita University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

The intermetallic compound TiAl is currently of interest as a new heat-resisting material at high temperatures, because it has high specific strength and stiffness associated with low density. One of the major problems for the practical use of TiAl is poor oxidation resistance at high temperature. It is expected that the formation of a Ti aluminide surface layer containing a high concentration of aluminum leads to the formation of an Al^2O^3 improving the oxidation resistance of the TiAl substrate. In the present work, the electrodeposition of aluminum on TiAl was performed using a NaCl-KCl-AlF^3 molten salt at 1023 K. The formation of a Ti aluminide surface layer containing a high concentration of aluminum was tried by alloying of aluminum with TiAl during the electrodeposition. Furthermore, the high temperature oxidation resistance of the TiAl alloy, covered with a surface layer containing a high concentration of aluminum, was evaluated as compared with untreated TiAl. The obtained r … More esults were as follows:1. When nickel specimen was cathodically polarized in NaCl-KCl containing AlF^3, an increase in cathodic current was observed in the potential region lower than -1.2 V (vs. Ag/AgCl(0.1)). It was found out that in this potential region the cathodic reduction reaction of Al^<3+> occurred.2. When TiAl specimen was cathodically polarized at -1.3 ~ -1.6 V (vs. Ag/AgCl(0.1)) in NaCl-KCl comtaining AlF^<3+> a deposited material having stratified morphology was formed. This material consisted of TiAl^3 and uniformly covered the TiAl substrate.3. The results of the oxidation experiments at 1273 K showed the oxidation resistance for TiAl covered with the deposited layer was very high. In this case, the formation of a protective α-Al^2O^3 film was observed on the surface of the deposited layer.Consequently, it was found that the Ti aluminide surface layer containing a high concentration of aluminum was formed by the electrodeposition of aluminum on the TiAl substrate using the molten salt and the formation of this surface layer led to improvement of the oxidation resistance of the TiAl substrate. Less

金属间化合物TiAl作为一种新型高温耐热材料目前受到关注，因为它具有高比强度和比刚度且密度低，其实际应用的主要问题之一是高温抗氧化性差。预计含有高浓度铝的Ti铝化物表面层的形成会导致Al^2O^3的形成，从而提高TiAl基底的抗氧化性。使用 1023 K 的 NaCl-KCl-AlF^3 熔盐在 TiAl 上进行铝化处理。通过在电沉积过程中将铝与 TiAl 合金化，尝试形成含有高浓度铝的 Ti 铝化物表面层。与未处理的 TiAl 相比，对表面覆盖有高浓度铝的 TiAl 合金的高温抗氧化性进行了评估，得到的结果如下： 1．将镍样品在含有 AlF^3 的 NaCl-KCl 中进行阴极极化，在低于 -1.2 V 的电位区域（相对于 Ag/AgCl(0.1)）观察到阴极电流增加。 2．当TiAl试样在-1.3～-1.6V(vs. Ag/AgCl(0.1))在含有AlF 3+ 的NaCl-KCl中形成具有分层形态的沉积材料。该材料由TiAl 3 组成并且均匀地覆盖TiAl基底。 3． 1273 K表明沉积层覆盖的TiAl的抗氧化性非常高，在这种情况下，在表面观察到保护性α-Al^2O^3膜的形成。结果发现，通过使用熔盐在TiAl基体上电沉积铝，形成了含有高浓度铝的Ti铝化物表面层，并且该表面层的形成导致了氧化的改善。 TiAl基体的电阻较小。