Microstructure-Property Correlation in Indigenously Produced Zinc-Aluminium Foundry Alloys

In recent times there is considerable spurt in R & D activities relating to Zinc-Aluminium foundry alloys for applications in bearings. In spite of the fact that zinc alloys have excellent properties like fluidity, lower melting points and excellent alloying behaviour, the zinc foundry alloy have not been finding the expected potential of application. This is due to the fact that trace amounts of impurities like lead, cadmium and tin aggravate the chances of intergranular corrosion and premature failure. In the present work various fluxes have been tried with a view to improving the microstructural features in Zn-8Al, Zn-12Al alloys. The results indicate that the use of a special flux improves the wear and corrosion resistance. Detailed metallographic investigations were carried out and are discussed in the paper. In the preparation of the alloys only the indigenously produced electrolytic grade zinc has been used which contains some amount of lead. The investigation showed that this flux treatment produces Zinc-Aluminium alloys having properties comparable with those produced using special high grade zinc.