Nanocoatings for the aviation engine parts developed by RTU

Riga Technical University (RTU) Institute of Aeronautics (AERTI) has developed innovative nanocoatings that can be used to cover parts of aviation engines made of titanium alloys. Such coatings have high erosion and heat resistance properties. They are also able to withstand the flow of high-temperature air over a long period of time. These coatings can be used not only in the airline industry, but also in the production of automotive and space technologies.

Lead researcher of AERTI Konstantins Savkovs explains that the main objective of the project “Development of innovative metal ceramic nanocoatings (McBLADE) of hot tract parts of gas turbine engines” was to develop titanium alloy coatings to increase their heat resistance in the temperature range of 700 to 850°C. Such coatings can be used for the new generation of gas turbine engines (GTDs) that have a low specific weight and consume less fuel. The development of such engines is currently one of the priority tasks in aviation.

The scientist has developed a methodology for creating a multilayer coating to use for titanium alloys. Each layer has certain functions. The first layer of intermediate metals provides good adhesion to the base material. The second layer provides the main protection against oxidation of the titanium alloy and performs protective functions and delays the resorption of the protective coating during operation. Whereas, the third layer additionally increases the resistance of the coating at high temperatures, and also improves its mechanical and chemical properties.

This coating is very thin, invisible to the naked eye. It must not be more than 10 micrometres thick to exclude the effect of the thickness of the coating on the aerodynamic properties of the blades of the last sections of the compressor with a maximum thickness of approximately one millimetre. All layers of coating must be implemented in one technological cycle without interrupting the process. To introduce this method, the vacuum equipment “NNV-6,6-I1” was modernized, a technology for applying each layer of coating was developed, determining all the technological parameters of the sediment.

All layers of coating were applied to titanium alloy samples separately as a monolayer with different chemical compositions of the coating. Oxidation tests of these monolayers were carried out between 750 and 850°C to determine the optimal composition of each layer separately and to make a preliminary assessment of the expected thickness of each layer. Multilayer coatings with different layer priorities were then applied and tested to determine the optimal ratio of the thickness of each layer of coating, and optimization of the final coating technology was carried out based on the results of all tests performed. The new coatings were tested for long-term heat resistance at 800, 850, 870°C.

Titanium alloys are one of the lightest materials currently used in the manufacture of gas turbine engines. Increasing their heat resistance will also increase the share of titanium alloys in engine design, significantly reducing the weight of gas turbine engines and, consequently, the mass of aircraft.

Replacing expensive nickel alloys with the most affordable titanium alloys will lead to a decrease in nickel consumption, thereby also increasing the production of more environmentally friendly engines. The coatings themselves are relatively ecological and not too expensive.

In Latvia, the use of the new technology could contribute to the development of high-tech products with high added value, and the developed technology can also be used in the automotive and space industries.

The postdoctoral research project has been developed within the framework of the sub-activity “Development of innovative metal ceramic nanocoatings (McBLADE) of hot tract parts of gas turbine engines” of the specific support objective “Increasing research and innovation capacity of scientific institutions of Latvia and the ability to attract external financing by investing in human resources and infrastructure” of the event “Postdoctoral Research Support” of the European Regional Development Fund operational programme “Growth and Employment”.

Source: labsoflatvia.com