Product Code: ICA10_P193

Laser Surface Alloying of Mn-Ni-Al Bronze for Cavitation Erosion Resistance
Authors:
Chi Tat Kwok, University of Macau; Macau Peoples Republic of China
Poo Kee Wong, University of Macau; Macau Peoples Republic of China
Fai Tsun Cheng, The Hong Kong Polytechnic University; Hong Kong Peoples Republic of China
Hau Chung Man, The Hong Kong Polytechnic University; Hong Kong Peoples Republic of China
Weng Kin Chan, University of Macau; Macau Peoples Republic of China
Presented at ICALEO 2010

Cavitation erosion of a metal surface is caused by the repeated nucleation, growth and collapse of cavities in vibratory and high-speed flowing liquid. It occurs on surfaces including propellers, pipelines, valves, pump impellers and casings, many of which are made of copper alloys. In order to improve the cavitation erosion resistance of Mn-Ni-Al bronze (MAB), alloyed layers of Cr, Ni and W with MAB substrate were achieved by laser surface alloying (LSA) using a 2.5-kW continuous wave Nd:YAG laser. The laser-alloyed layers have a thickness of 250 μm and exhibit very fine microstructure. The microstructure, hardness, corrosion, cavitation erosion resistance of the laser-alloyed specimens were studied and compared with the MAB substrate. The microhardness of the alloyed layers was significantly and uniformly increased. The cavitation erosion and corrosion behavior of the LSA coatings in 3.5% NaCl solution at 25 °C was studied with a vibratory cavitation tester and a potentiostat. The cavitation erosion resistance of the alloyed layers was improved by more than two times compared with that of the MAB substrate. In addition, the corrosion resistance of the alloyed layers was also enhanced as reflected by the shift of the polarization curves towards lower current densities.