Microstructure and Corrosion Property of Prepared CoCrW Coatings on the TC4 Surface by Laser Cladding

Abstract

Ti6Al4V (TC4) is widely used in aerospace, marine equipment, and the petrochemical industry. However, the dense oxide film on the surface of this alloy will be destroyed in reducing acid solution, resulting in surface corrosion in practical application. To enhance the corrosion resistance of TC4 in marine environments, this study employed laser cladding technology to deposit a CoCrW cladding layer on the TC4 alloy surface. Experimental results validated the successful preparation of a dense, crack-free CoCrW layer. The microstructure of the CoCrW layer was characterized by predominant bulk grains and minor equiaxed crystal constituents, demonstrating a robust metallurgical bond to the matrix. Notably, the corrosion resistance of the TC4 surface witnessed a marked improvement, evident from the CoCrW coating’s increased open circuit potential, elevated electrochemical impedance spectroscopy (EIS) radius, phase angle, and impedance modulus values. The corrosion rates of both the TC4 and CoCrW cladding layers escalated with extended immersion time and increased immersion corrosion temperature. However, the CoCrW cladding layer reported minimal mass loss and the least corrosion rate. In summary, the CoCrW coating, when prepared via laser cladding on the TC4 surface, markedly bolstered corrosion resistance.