In this study, aluminium hybrid composites were fabricated by reinforcing eco-friendly agrowaste, groundnut shell ash and boron carbide using squeeze casting method. Groundnut shell ash and boron carbide were added in ratios of 2.5:7.5, 5:5 and 7.5:2.5 percentages by weight. The impact on mechanical properties namely density, hardness, tensile strength, impact strength was studied, and the results were compared with the matrix alloy. The fracture mechanism of tensile and impact specimens were studied by scanning electron microscopy. Microstructural study reveals the uniform distribution and good bonding of reinforcements with clear interface in the hybrid composite. The hardness and tensile strength increased up to a maximum of 17% and 18.32%, respectively, and then slightly decreased while increasing groundnut shell ash particles. Increasing groundnut shell ash particles in hybrid composites decreases the impact strength and density to a maximum of 12% and 7.5%. Dimples, voids, cracks, clusters and particle fracture are characterised by fracture mechanism. Brittle fractures in the form of cracks, and particle fractures were formed due to the solid interfacial bonding between the reinforcements and alloy. Ductile fractures are the reason for high impact strength and are characterised by dimples and voids. The eco-friendly groundnut shell ash has the potential to serve as reinforcement for the development of composites.

No literature exists on the influence of the velocity of Cu powder particles (during cold spraying) on the properties of the coatings like porosity, hardness, electrical conductivity, residual stress, and microstructure. Similarly, though the occurrence of dynamic recrystallization in the Cu powder particle during its deformation under the cold sprayed process has been well documented, its influence on the properties of the coating has not been studied. In this study, it is shown that while porosity of the coating is determined directly by the powder particle velocity, the other properties like hardness, electrical conductivity, and residual stress are determined not only by the particle velocity which depends on stagnation pressure and preheating temperature of the air (process gas) but also additionally on preheating temperature of air per se. The extent of powder particle fragmentation and dynamic recrystallization as a function of particle velocity has been quantified in terms of the grain boundary area fraction and the influence of the latter parameter on the coating properties has also been presented.

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In any machining process, the vital part is determination of the optimum values for the process parameters to attain the highest desired quality at a low machining cost. This paper mainly focuses on the surface-roughness optimization in the turning of a hybrid aluminium-matrix (LM24-SiCp-coconut shell ash) composite through the Taguchi method and a genetic algorithm. All composite samples for the study were prepared under the optimal squeeze-casting conditions and experimental trials were selected based on the L9 (3) 4 orthogonal array. The main response considered in this study related to the surface roughness, and machining parameters such as the cutting speed, feed rate, depth of cut and tool-nose radius were taken into consideration. The surface roughness was tested on the composites turned with a high-speed CNC lathe machine. From the experimental data, a regression model of the surface roughness was developed. The optimum machining conditions were obtained through the Taguchi method and a genetic algorithm and checked through confirmation experiments. In this study, it was concluded that the genetic algorithm used for determining the optimum machining conditions showed better results than the experimental outcome based on the orthogonal array and the optimum conditions obtained with the Taguchi method. Keywords: LM24 aluminium alloy, silicon carbide particles, coconut shell ash, surface roughness, Taguchi method, genetic algorithm V katerem koli postopku mehanske obdelave je klju~nega pomena dolo~itev optimalnih procesnih parametrov, ki omogo~ajo najvi{jo zahtevano kakovost obdelave pri najmanj{ih stro{kih. Avtorji so se v glavnem osredoto~ili na optimizacijo parametrov stru`enja, ki dolo~ajo povr{insko hrapavost hibridnega kompozita (LM24-SiCp-pepel kokosovih lupin) z Al matrico. Za to so uporabili Taguchijevo metodo in genetski algoritem. Vsi vzorci za pri~ujo~o {tudijo so bili izdelani s postopkom visoko tla~nega litja v testastem stanju (angl.: squeeze casting) pri optimalnih parametri~nih pogojih. Eksperimentalni preizkusi so temeljili na izbrani L9 (3) 4 ortogonalni matrici. Glavni vplivni parametri povr{inske hrapavosti, obravnavani v tej {tudiji, so bili: hitrost rezanja, hitrost podajanja, globina reza in polmer konice plo{~ice rezilnega orodja. Povr{insko hrapavost kompozitnih vzorcev so preverjali z merilnikom Mitutoyo SJ-210 po zelo hitrem stru`enju na ra~unalni{ko vodeni (CNC) stru`nici. Na osnovi eksperimentalnih podatkov so razvili regresijski model za povr{insko hrapavost. Optimalne pogoje mehanske obdelave so dosegli s pomo~jo Taguchijeve metode in genetskega algoritma in jih preverili s pomo~jo eksperimentalnih postopkov. Avtorji zakljuujejo, da optimalni pogoji mehanske obdelave, dolo~eni z genetskim algoritmom, dajejo bolj{e rezultate kot eksperimentalni rezultati, ki temeljijo na optimalnih pogojih, dolo~enih s Taguchijevo metodo za izbrano ortogonalno matrico. Klju~ne besede: Al zlitina LM24, silicij karbidni delci, pepel kokosovih lupin, povr{inska hrapavost, Taguchijeva metoda, genet...