Influence of Acid Concentration in Combined Cleaning of Gas Turbine Nozzle Blades from Metal Oxides

The method of chemical cleaning of the surface of blades of gas turbine units in a solution of orthophosphoric and sulfuric acids using a purpose-designed closed-type autoclave microwave system “Mars 5” and ultrasonic exposure in distilled water is described. The two-stage cleaning involves the chemical action of the acid solution in the autoclave and ultrasonic cleaning in the stage of washing. The effect of acid solutions of various concentrations on the degree of surface cleaning from metal oxides and microcracks in the gas turbine blades is studied. It is shown that when the samples of gas turbine blades are treated in the “Mars 5” autoclave with a solution of acids and with ultrasound in the washing stage, the residual oxygen content reflecting the presence of oxides on the surface of the samples is less than 1%.