A comparative assessment of tensile strength and corrosion protection in friction stir processed aa7075-t651 matrix composites using fly ashes nanoparticles as reinforcement inhibitors in 3.5 % NaCl

This research presents the performance of eco-friendly waste materials, which are wood fly ash nanoparticle (WFA-NPs) and coal fly ash nanoparticles (CFA-NPs) as economical reinforcements corrosion inhibitors on friction stir processed Aluminium 7075-T651 alloy in 3.5 % NaCl solution at room temperature and at a stable pH of 7. This study investigated the tendency of using domestic waste wood fly ash and industrial waste coal fly ash as a promising and potential alternative to metallic powders for reinforcements and corrosion mitigation in friction stir processed (FSP)armour grade aluminium 7075-T651 alloy and at the same time compare their efficacy. Microchannel of 3.5 mm depth and 2.0 mm width was machined on each aluminium plate with the aid of horizontal milling machine to deposit fly ashes (FAs) nanoparticles. Optimum process parameters chosen for the FSP experimentation are processing speed, rotational speed, tool tilt angle and plunging depth which were 20 mm/min, 1500 rpm, 3 ° and 0.3 mm respectively. Two passes on each parameter with 100 % inter-pass overlap was achieved. A cutting tool with a tapered cylindrical pin profile made of AISI H13 steel tool was employed for FSP with a shoulder diameter of 18 mm, pin diameter of 5 mm and a pin length of 5 mm. In this study, the tensile strength was investigated using X force P type of Zwick/Roell Z250 tensile testing machine with a normal force of 250 KN and characteristic of 2mV/v. It was revealed that unprocessed and untreated base metal (UBM) has the highest values for ultimate tensile strength which were 620.9030 MPa and its breaking force was 22.35252 KN with an elastic modulus of 9.38165 GPa. There was no significant improvement in tensile strength properties when processed and or reinforced with either WFA-NPs or CFA-NPs. In contrast, there was tremendous and excellent improvement in corrosion protection ability of calcined WFA-NPs as against CFA-NPs when applied as reinforcement inhibitor which lead to reduction in corrosion rate from 5.0718 to 0.12068 mm/year with the highest percentage corrosion inhibitive performance efficiency (%IPE) from 63.9 % on reinforced to 97.61 % reinforced with WFA-NPs.