Aspects of porosity formation in spray deposited thin aluminium strip

摘要

A characteristic feature of the spray deposited metal strip is that it contains porosity. The present paper has reported and explained the effect of various process parameters such as atomising pressure, deposition distance, melt superheat and melt delivery tube diameter on porosity of the spray deposited thin aluminium strip. Porosity of the spray deposited aluminium strip greatly depends not only on the liquid fraction present on the substrate, but also on the thermal condition through the substrate. It has been shown that there are several types of porosity present in the strip, namely interstitial, mechanically entrapped gas, intersplat boundary, solidification shrinkage and porosity due to hydrogen evolution. The mechanism of their formation has been discussed. An increase in the initial temperature of the substrate lowers the porosity content in the spray deposited aluminium strip.