An experimental investigation of Cu-Ni-Sn alloy on microstructure, hardness and wear parameters optimization using DOE

Abstract

Copper-Nickel-Tin (Cu-Ni-Sn) spinodally decomposable alloy of composition Cu-7Ni-4Sn was prepared by using sand casting process. The specimens required for microscopic examination, micro-hardness and wear tests were prepared from heat treated (homogenization, solution and ageing) cast rods. The microscopic examination results revealed that the as-cast dendrite structure was disappeared during the homogenization, solution and ageing processes and forms grains of various sizes with respect to ageing time. The hardness of the alloy was increased from 206 HV at solution treated condition to 235 HV at four hours of ageing. By using pin-on-disc wear tester in dry sliding condition an adhesive wear test was conducted as per L9 orthogonal array by taking parameters of applied load, sliding speed and ageing time. An optimum level of parameter for each case was determined through S/N ratio investigation by considering "smaller-the-better". From this investigation, it was found that the parameter ageing time was the dominant as compared to other two parameters. The significant parameter that affect the response was indicated by the results obtained from ANOVA and these results were agreed with S/N analysis. The developed linear regression equation was validated through confirmation experiments. The wear mechanism was observed on worn out surfaces by selecting appropriate specimens considering applied load and sliding speed for both normal and optimum parameter specimens using scanning electron microscope (SEM).