Hardness of Electrodeposited Speculum Metal and other Tin-Copper Alloys

SYNOPSIS

This paper presents the results of 136° diamond pyramid hardness studies carried out on electrodeposited speculum metal and other tin-copper alloys of various compositions. The deposit composition has a distinct effect on the hardness value of the deposit. Among the different tin-copper alloy deposits studied speculum has the greatest hardness, its D.P.H. being 520±9. Further, these deposits on the evidence of the hardness tests are found to be compact, homogeneous and isotropic. The influence of the base metal on the measurement of hardness of these coatings has been investigated in detail. So long as the depth of penetration of the diamond pyramid is less than ⅛th the thickness of the plating, the measured hardness is characteristic of the deposit and is uninfluenced by the base metal.