No abstract

Aluminium alloys are being widely used in naval applications owing to their excellent corrosion resistance and high formability characteristics. One of the most popular naval components is the tarpedo blade which makes use of forged aluminium alloy followed by anodizing surface treatment for corrosion protection. In recent years, there have been few attempts to replace the conventional aluminium alloys by their composites for the tarpedo blade applications. Literature review clearly says that CeO2 (Ceria) coating on aluminium and aluminium composites enhances their corrosion protection in aggressive marine environment. Further, there are reports suggesting that combination of CeO2 and TiO2 do yield better corrosion protection. However, there is no information on the work related to development of hybrid ceramic reinforced aluminium alloy matrices with CeO2 and TiO2 as particulate reinforcements for potential naval applications. In the light of above, the present work focuses on the development of novel Al6061-CeO2-TiO2 hybrid metal matrix composite by stir casting route followed by hot extrusion with an extrusion ratio of 8:1 at a temperature 550 °C and hot forging at 475 °C. The developed forged hybrid composites and the matrix alloy have been evaluated for microstructure, micro hardness and slurry erosion wear tests as per the ASTM Standards.

Extrusion of metal matrix composites (MMCs) is a very challenging one where in the bond between the reinforcement and the matrix alloy is crucial in getting high quality extrusions for industrial applications. In recent years researchers are focusing on developing aluminium based composites with metallic coated reinforcement to achieve good interfacial bonds to ensure smooth load transfer from the matrix on to reinforcement. However no information is available as regards hot extrusion of metallic coated reinforced MMCs. In the light of the above, the present work focuses on a systematic investigation on effect of extrusion process parameters on mechanical properties of Al6061-Ni-P coated SiC composites. From the investigation, it is observed that hardness, yield and ultimate strength of Al2014-SiC (Both uncoated and Ni-P coated) composites are higher when compared with the matrix alloy for all the extrusion ratios studied (4:1,5:1,10:1,15.5:1) at a given extrusion temperature. However, the ductility of composites decreases with increase in extrusion ratios. Further, heat treatment has a significant effect on the studied mechanical properties. Increase in extrusion temperatures at a given extrusion ratio has resulted in decrease in hardness and strength properties of both matrix alloy and developed composites.