Fabrication of Composite Heat Sinks Consisting of a Thin Metallic Skin and a Polymer Core Using Wire-Arc Spraying

Abstract

Three composite heat sinks in the shape of a disk, a cylinder, and a cylinder with vertically projecting fins were made by applying a thin (0.4 – 0.7 mm) zinc layer onto ABS polymer cores using wire-arc spraying. The influence of spray distance and surface roughness on the adhesion strength between the zinc and ABS layers were investigated and a maximum adhesion strength of 2.6 MPa was obtained. An analytical model of the heat conduction in an annular fin was developed, assuming one-dimensional heat conduction in the metal coating and two-dimensional conduction in the polymer core. The temperature distribution along the disk-shaped heat sink was measured using an infra-red camera and found to agree well with the developed model. The calculated temperatures at the base of the heat sink also agreed with measured values as heater power was varied. The model was used to examine the effect of fin radius and coating thickness on fin efficiency.