Development of oxidation and fretting-wear resistant coatings on Titanium Aluminide (TiAl) components

燃气涡轮发动机的推重比很大程度上取决于所用材料的性能。为了实现高发动机效率，人们可以特别受益于使用轻质材料耐高温和高机械强度。近年来，TiAl基合金由于具有低密度、高比强度、高弹性模量和高温下良好的抗蠕变性能，在航空航天领域的高温应用中显示出相当大的潜力。然而，由于这种材料的机械和环境限制，大多数涉及TiAl合金的应用不超过750°C。在此高温以上形成Al2O3和TiO2的非保护性混合物，导致ti合金氧化变质。针对上述限制，拟议研究的主要目标是开发涂层和表面处理，允许在高温（750-850°C）下使用金属间TiAl成分。这些涂层应同时具有良好的抗氧化性和微动磨损性，并且不应损害部件的疲劳特性。这项研究活动有可能对其他技术领域产生重大影响。

The thrust-to-weight ratio of a gas-turbine engine strongly depends on the performance of the materials involved. In order to achieve high engine efficiency, one can particularly benefit from the use of lightweight materials with high temperature resistance and high mechanical strength. In recent years, TiAl based alloys have been shown to exhibit considerable potential for high-temperature applications in aerospace due to their numerous attractive properties including low density, high specific strength, high elastic modulus and good creep resistance at high temperature. However, most of the applications involving TiAl alloys do not exceed 750°C due to mechanical and environmental limitations for this type of material. Above such high temperature non-protective mixture of Al2O3 and TiO2 is formed, leading to the Ti-alloy oxidation and deterioration. In response to the above limitations, the main objective of the proposed research is to develop coatings and surface treatments that would allow the use of intermetallic TiAl components at elevated temperatures (750-850°C). These coatings should simultaneously possess good oxidation and fretting-wear resistance, and they should not compromise the component fatigue characteristics. This research activity represents a possibility to strongly impact also other technological areas.