Investigation of Efficiency of Cleaning the Surface of Gas Turbine Engine Blades from Metal Oxides Using Halide-Containing Compounds

The nozzle blades of a gas turbine engine (GTE) are an important part of an aircraft engine. During operation, the nozzle blades are exposed to high temperatures, mechanical loads, sulfide and salt corrosion. Due to the influence of aggressive factors, carbon deposits, metal oxides and microcracks form on the surface of the blades of the gas turbine engine. To restore the performance characteristics of the blades, it is necessary to clean the surface of the blades from aluminum, titanium, tungsten, chromium, and nickel oxides. Based on the analysis of literature sources, it is shown that many detergents are not able to remove these oxides with high chemical resistance from the surface of the blades. In the article, halide-containing substances such as hydrogen fluoride gas, hydrofluoric acid, and hydrochloric acid were used to clean the blades from metal oxides. The main purpose of this work was to study the efficiency of cleaning the surface of the GTE nozzle blade with halide-containing compounds from carbon deposits and stable metal oxides of aluminum, titanium, tungsten, chromium, and nickel. The composition of the material used in the study and the analytical tools used to determine the surface composition of a sample of a GTE nozzle blade made of an alloy of the KHN54KVMTYUB brand are described. The methodology and conditions of the processes of exposure to gaseous hydrogen fluoride, hydrofluoric and hydrochloric acids are considered. The features of the effect of halide-containing substances on stable metal oxides on the sample surface have been studied. It was found that hydrogen fluoride gas reacts actively with aluminum and tungsten oxide, thereby destroying the basic structure of the oxide film. Hydrofluoric acid also reacts with the components of the KHN54KVMTUB alloy, accompanied by a thinning of the oxide layer and a decrease in the oxygen content on the surface. When cleaning with hydrochloric acid using ultrasonic treatment, depressions appeared on the surface of the blades. Thus, halide-containing reagents actively react with the surface of the KHN54KVMTUB alloy, which helps to clean the blades from the oxide layer.