In many applications, surface properties of materials or components are more important than the entire volume material properties. The hardness, wear and corrosion resistance of material mainly depends on the surface properties. Improved surface properties also increased the life span of components. The friction stir process is a novel solid-state processing technique that is widely used for welding difficult-to-weld materials. In this paper, the applications of the friction stir process in surface modifications and fabrication of aluminum matrix surface composites were discussed. The effects of friction stir process parameters, tool design, reinforcement and reinforcement techniques on the surface properties were also reported.

Friction stir welding is a novel solid-state welding process for joining aluminum alloy components. The heat generation, proper mixing of joint line material and properties of welds depends on the profiles of friction stir tools. Aluminum alloy Al 1120 plates were welded via friction stir welding using deferent friction stir tools. The effects of tool pin profile on mechanical properties were reported in this paper. The result reveals that weld joints formed with a taper threaded pin tool exhibited better tensile and flexure strength. However, welds formed with a cylindrical threaded pin tool showed higher hardness and impact strength.

The Pine Leaf tree is a high altitude plant that is mostly found in the Himalayan region. The pine leaf ash contains the hard compound of Si, Ca, K, Mg, and Fe which make it an alternative cost-effective reinforcement material for composites. In this paper, the surface composite of aluminum alloy reinforced with Pine Leaf Ash was developed by friction stir process (FSP) with varying tool feed rate using different profile pin tool at constant 1400 rpm. The effects of tool pin profile and feed rate on hardness and tribological properties of the fabricated surface composite were reported. It was found that composite fabricated at 56 mm/min feed rate with threaded taper pin tool exhibited highest hardness and lowest wear rate amongst all fabricated composites. The hardness and wear properties of composite fabricated with threaded pin tool improved 15.81 and 18.13%, respectively.

The present paper deals with the examination of mechanical and tribological behavior of glass fiber reinforced epoxy composite. Wood flour (WF) is added as filler in glass fiber (GF) and epoxy matrix material for the fabrication of composites. The Percentage of WF is varied from 2.5 wt. % to 10 wt.% keeping the glass fiber constant. The mechanical properties, water absorption and tribological behavior of fabricated composites evaluated. It was found that water uptake increases as the percentage of WF in the composite increases i.e. from 2.5 wt. % to 10 wt. % and it was least for neat GF reinforced epoxy composite. The composite of WF wt. % of 7.5, absorb maximum energy and exhibited maximum strength. Moreover the wear rate increases as the percentage of WF in the composite increases. Present investigation also deals with the design of experiment (DOE). The DOE was carried out with the help of TOPSIS for the qualitative analysis and the ranking were done according to the order of preference.