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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具有高比强度、高比刚度和低密度特性，是目前人们关注的一种新型高温耐热材料。影响TiAl实际应用的主要问题之一是高温下抗氧化性差。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基板的抗氧化性。本文采用NaCl-KCl-AlF^3熔盐在1023 K的温度下在TiAl上电沉积铝。在电沉积过程中，将铝与TiAl合金化，试图形成含有高浓度铝的Ti铝化物表面层。此外，与未处理的TiAl相比，在表面覆盖一层含有高浓度铝的TiAl合金的高温抗氧化性进行了评估。实验结果如下：1。当镍试样在含al ^3的NaCl-KCl中阴极极化时，在低于-1.2 V的电位区阴极电流增加（相对于Ag/AgCl(0.1)）。结果表明，在该电位区发生了Al^<3+>的阴极还原反应。在含al ^<3+>的NaCl-KCl中，在-1.3 ~ -1.6 V （vs. Ag/AgCl(0.1)）阴极极化时，TiAl试样形成具有层状形貌的沉积材料。这种材料由TiAl^3组成，并均匀地覆盖在TiAl基板上。1273 K下的氧化实验结果表明，沉积层覆盖的TiAl具有很高的抗氧化性。在这种情况下，沉积层表面形成了一层保护性的α-Al^2O^3薄膜。结果表明，采用熔盐在TiAl基板上电沉积铝，形成了含有高浓度铝的Ti铝化物表面层，该表面层的形成提高了TiAl基板的抗氧化性。少