SYNTHESIS OF COPPER-GRAPHITE COMPOSITE USING FRICTION STIR PROCESSING AND EVALUATION OF OPTIMAL PARAMETERS USING TAGUCHI ANALYSIS

Abstract

This report is concerned with the fabrication of surface composites. Surface composites are a group of modern engineered materials where the surface of the material is modified by dispersing secondary phase in the form of particles or fibers and the core of the material experience no change in chemical composition and structure. The potential applications of the surface composites can be found in automotive, aerospace, biomedical and power industries. Recently, friction stir processing (FSP) technique has been gaining wide popularity in producing surface composites in solid state itself. Friction Stir Processing (FSP) is a solid state surface composites producing process which uses a non-consumable rotating tool inserted into the workpiece for heating and softening the material. This results in material severe plastic deformation resulting in improved mechanical properties and refined grain structure. Most of the research conducted on FSP is confined to aluminum alloys; limited study is done on FSP of copper based alloys. Friction stir processing has been utilized to create metal matrix composites by consolidating graphite particles in a copper material matrix. Mechanical properties (i.e. tensile and hardness/microhardness, wear resistance etc.) of the matrix metal matrix composites reinforced with graphite particles. Tensile tests exhibited decrements in yield strength. The average microhardness value within the stir zone decreased from 180 HV in the base material to a minimum of 142HV in a graphite reinforced composites. Wear resistance is enhanced with decrease in the friction coefficient from 0.490 of standard specimen to minimum of 0.168.