In-situ Manufacturing of Al7075/TiO2, Al7075/SiC and Al7075/TiO2/SiC Based Composite Layers by Friction Surfacing on Commercially Pure Aluminum

Al7075/TiO2 and Al7075/TiO2/SiC composite layers were produced on the surface of commercially pure aluminum substrate (CP Al) using friction surfacing. SiC and TiO2 particles were introduced into axial holes drilled on the cross section of cylindrical Al7075 pins that used as primary consumable material for the friction surfacing process. Cross-sectional scanning electron and optical microscopy images of the specimens showed a uniform distribution of the reinforcing particles within the composite layers. Grain sizes were decreased significantly after addition of the ceramic particles. SiC had a greater effect on grain refining of the composite layers than TiO2. Microhardness improved after addition of the reinforcing particles and adding SiC particles had increased the microhardness more than TiO2. Wear tests showed that the wear resistance of aluminum can be increased dramatically by friction surfacing and by addition of the ceramic particles. SiC increased the wear resistance of the composite layers through its high grain refining role, while TiO2 improved the wear resistance by production of the lubricating oxide layers. The sample containing of the both reinforcing particles showed the highest wear resistance.