Repair of damaged surfaces of components of turbine and hydromechanical equipment through the use of cold metallization

Abstract

Cold metallization includes the powder or wire application on the cold surface of components by electric arc, gas, plasma, supersonic, gas-detonation method. It could be applied on all metals except on pure copper, but not on glass and non-metallic materials. Thickness of the layer which is being deposited ranges from 0.05 to 5 mm. Porosity of the layer is 3-15 %. Temperature of the parent material does not exceed 250°C, and therefore it sustains its mechanical properties. Taking into account the above mentioned, for the repair of damaged surfaces of components of turbine and hydromechanical equipment, the methodology of the electric arc technique was developed. At first, research regarding the possibility of application of cold metallization at damaged samples of metal sheets and pipes made of structural steel was carried out, and afterwards the same methodology was performed and confirmed during the repair of damaged surfaces of the flange at the horizontal Kaplan turbine with nominal power of 28 MW (Djerdap 2). Functional role of the flange, made of steel X5CrNi18-10, is to prevent the water from entering the enclosed space of the turbine shaft.