This study emphasis on a novel fabrication technique to fabricate hybrid cermets using Al 6061 alloy with nano sized SiC, Al2O3 and TiO2 as reinforcements. During the fabrication process, the melted pool was ultrasonicated to disperse nanoparticles at 20 kHz for 5 min and pressure of 50 MPa was applied to eliminate voids. The influence of nanoparticles on physical, thermal and mechanical properties were evaluated by tensile, wear and thermal studies. Cermets with Al2O3 reinforcements showed higher mechanical performance compared to Al alloy. This enhancement could be related to the uniform distribution of Al2O3 with refinement in grain size of Al alloy which was observed via surface analysis. The morphological studies provided justifiable evidence of homogeneous distribution, nominal cluster along with agglomeration and cavities shrinking on the cermets. The agglomeration of nanoparticles along with SiC protected the cermet in corrosion and abrasive wear by ~ 97% and ~ 71%. The study evidenced the novel fabrication method using ultrasonic rheo-squeeze casting led to improvement in mechanical and thermal properties of the hybrid cermets. Graphical abstract

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Performance of the proton exchange membrane (PEM) fuel cell depends on the operating pressure, operating temperature, stoichiometric ratio of reactant gases, relative humidity, and rib width-to-channel width ratio (R:C), shape of the flow channel, and the number of passes on the flow channel. The effect of pressure, temperature, inlet reactant mass flow rate and rib width-to-channel width ratios of 1:1, 1:2, 2:1, and 2:2 on the power density of a PEM fuel cell with interdigitated flow channel of 25 cm 2 active area of was considered in this study. The response surface methodology was used for optimizing the four above mentioned parameters to find the optimum power density of the PEM fuel cell. The analysis of variance (ANOVA) was used to find the contribution of each parameter to the performance of the PEM fuel cell. Further, numerical results were compared with the experimental validation of the PEM fuel cell. Numerical results of power densities of interdigitated flow channel with R:C ratios of 1:1, 1:2, 2:1, and 2:2 were found to be 0.272, 0.292, 0.267, and 0.281 W/cm 2 and the corresponding experimental results of power density were 0.261, 0.266, 0.254, and 0.264 W/cm 2 , respectively.