Development of high temperature corrosion resistant coatings applicable to air vehicles

The subjects related to air and space vehicles are important research and development areas in our country. Selection of materials to be used in air and space vehicles, production and extension of their life, are among the research topics that can be studied. Despite the mechanical strength, the use of metallic materials was limited and the use of light composites increased due to the efficiency and fuel saving in aviation. However, in high temperature systems such as motors, metal alloys with high melting temperatures are indispensable. In aircraft design, high temperature corrosion is a rapidly progressive threat. This is seen in gas turbines and pipelines carrying hot fluids; It can be prevented by increasing the frequency of maintenance and repair, changing parts or alloying the part and making it resistant to corrosion. Nickel superalloys used in energy and aerospace fields have reached working limit at 1200oC and the need to develop alloys has increased. Due to the melting temperature above 2000°C, refractory metals are considered to be the next generation of high temperature alloy materials. However, they cannot form a protective oxide layer in the air. In order to increase the corrosion resistance, high temperature coatings should be applied on them. The aim of the thesis; is the production of coatings which will delay the oxidation damage and increase the life of the metallic parts of the systems and vehicles used in aviation in oxidizing environments such as high temperature air. In this study; the methods of coating high temperature oxidation resistant alloys on metal surface were investigated. Coatings were made in the specified compositions on niobium refractory metal by cementation method and short - long term oxidation tests were applied. The developed coatings were examined with characterization devices. In all coatings, niobium aluminate phase and in co-deposited coatings, niobium silicate phase was formed. All the coating compositions obtained increased the oxidation resistance of niobium.