Investigation of Cu-SiC Composite Preforms during Cold Upsetting

Abstract

Cold upsetting experiments were carried out on sintered Cu-SiC preforms in order to evaluate their deformation characteristics. Powder preforms of 0.85, 0.90, and 0.95 initial preform density and 0.60 of initial aspect ratio were subjected to incremental compressive loading of 0.02 MN until fracture appeared at free surfaces. The effects of silicon carbide content and initial fractional density of the preforms on deformation behavior have been investigated thoroughly by using Zinc stearate as a lubricant. Dimensions such as height, contact, and bulged diameters, and densities were measured for each test. Analysis of the experimental data has shown the power law relationship between fractional theoretical density and e ^{(ϵ _z −ϵ_θ)}. Further, it was found that the preforms of lower silicon carbide content show higher values of deformation properties like the axial stress and the Poisson's ratio than higher silicon carbide preforms, provided that the initial fractional density taken is kept constant.

Keywords:

• Cold upsetting
• Cu-SiC preforms
• Densification
• Poisson's ratio