In this study, a hybrid surface composite of AA5083/SiC-Gr was produced by Friction Stir Processing (FSP). Reinforcement material each in 50:50 proportion was filled in the base matrix using holes method. Three different hybrid reinforcement volumes of 301.6 mm ³, 452.4 mm ³, and 603.2 mm ³ were prepared for surface composite. Optical and Scanning Electron Microscopy was used to check the quality of the prepared surface composite and homogeneous distribution of reinforcement was observed in the images. It was observed that due to better uniform distribution of reinforcement particles during 3 pass FSP, specimens with 301.6 mm ^3/ reinforcement volume showed enhanced microhardness and wear properties in comparison with the other specimens. Keywords: Surface Composites; Multi-pass; Friction Stir Processing; Reinforcement; Hybrid Composite

The present work investigates the effect of modifying an epoxy resin using two different modifiers. The mechanical and thermal properties were evaluated as a function of modifier type and content. The structure and morphology were also analyzed and related to the measured properties. Polyurethane (PUR) was used as a liquid modifier, while Cloisite Na+ and Nanomer I.28E are solid nanoparticles. Impact strength (IS) of hybrid nanocomposites based on 3.5 wt% PUR and 2 wt% Cloisite or 3.5 wt% PUR and 1 wt% Nanomer was maximally increased by 55% and 30%, respectively, as compared to the virgin epoxy matrix, exceeding that of the two epoxy/nanoparticle binaries but not that of the epoxy/PUR binary. Furthermore, a maximum increase in IS of approximately 20% as compared to the pristine matrix was obtained with the hybrid epoxy nanocomposite containing 0.5 wt% Cloisite and 1 wt% Nanomer, including a synergistic effect, due most likely to specific interactions between the nanoparticles and the epoxy matrix. The addition of polyurethane and nanoclays increased the thermal stability of epoxy composites significantly. However, DSC results showed that the addition of flexible polyurethane chains decreased the glass transition temperatures, while the softening point and the service temperature range of epoxy nanocomposites containing nanofillers were increased. FTIR analysis confirmed the occurrence of interaction between the epoxy matrix and added modifiers. All SEM micrographs showed significant roughness of the fracture surfaces with the formation of elongated platelets, explaining the increase in mechanical properties of the epoxy matrix.

A characteristic study on the phenol formaldehyde (PF) composite is carried out based on the micro level bio waste particles such as wood sawdust (WSD) and coir pith (CP). Composite is characterized by mechanical properties such as tensile, flexural and impact at different percentages of particles (0-50% by weight) to find out the optimum percentage of particle loading to get the maximum properties. The WSD/CP/PF hybrid composite is also prepared by two different methods i.e., one: one (1:1) ratio and rule of mixture. The first method (1:1) is used to find out the optimum level of hybrid particles loading to get the maximum properties. But, the second method is followed to find out the weight percentages of particles influencing the properties of resulting composite. The results show that the mechanical properties of WSD/PF are higher than CP/PF composite in the entire particle loading. The optimum particle loading to get the maximum properties is 40 wt.% in CP/PF composite, whereas for WSD/PF composite are at 30 wt.%. The hybrid composite (1:1) also gives the maximum properties at 30 wt.%. Moreover, the hybrid composite (20WSD/10CP) prepared by rule of mixture showed the highest mechanical properties compared to the other particle loading. It is identified that the WSD particles are most influencing the properties of PF composites than the CP particles. Fractographic study was performed using scanning electron microscope to examine the failure mechanism of the composite specimens.

In the present study, the mechanical properties and high-temperature sliding wear behaviour of the Al6082-SiC-TiO2 hybrid composite in different environmental conditions produced by the stir-casting process were investigated and distinguished with single-reinforced composites (Al6082-SiC and Al6082-TiO2) and matrix alloy. The microstructure of composites exhibited a reasonably uniform scatter of particles in the aluminium matrix with good bonding between the matrix-particle interfaces. The hybrid composite’s hardness and ultimate tensile strength showed higher hardness and tensile strength than matrix alloy and single-reinforced composites, whereas trends were reversed for the elongation. The impact test of the materials was conducted at different temperatures (room temperature, 0°C, –25°C, –50°C, and –75°C). The hybrid composite shows higher impact strength than the other materials, and impact strength decreases with temperature because ductility decreases with temperature. The fracture surfaces were examined to identify the fracture mechanism. The sliding wear test was conducted at different temperatures (room temperature, 100°C, 175°C, 250°C and 325°C) to distinguish the tribological behaviour of materials. The weight loss of the materials was increased with an increase in temperatures. The hybrid composite shows a lower weight loss than the other condition samples, irrespective of the temperatures. The wear surfaces were examined to predict the material removal mechanism.