Ravi Kumar V.

Presently there are lot of materials that can be used in the fabrication of any item, so choosing a material is a major criteria. So the materials are chosen depending on the properties desired by the resulting item. The composite materials have better properties when compared with its individual components, metals and ceramics. The overall appeal of the product depends mainly on its durability, aesthetics and its final cost. Composite materials are cost effective and significantly satisfy the needs of the clients. By utilizing composite materials we can obtain high strength to weight ratio at a relatively economical cost. Moreover, they can be produced easily by basic part forming. Hybrid polymer composites have been studied of late which improves a specific property of the composite that is under question. Here a hybrid composite made of laminate of Nomex and HS glass sheets with varying percentage (1% - 2.5 %) of bisphenol dispersed in resin is prepared. The same samples were subjected to cryogenic treatment (24 hrs and 72 hrs). The results of tensile strength, flexural strength and hardness were compared for all the specimens 24 hrs cryogenic, 72hrs cryogenic and non-treated specimens. The results showed that the hardness of the cryogenic treated bisphenol based PMCs has increased with the weight percentage of Bisphenol indicating the fact that the laminates can withstand more loads at subzero temperatures The increase observed was about 3 – 4 % more in terms of BHN number. At the same time the tensile and flexural strengths have considerably reduced after treating the PMC cryogenically as the laminates becomes more brittle when treated. The tensile strength increased by about 10% approximately and the flexural strength reduced by 300%

The present work deals with the characterisation polymer matrix composites combining glass fiber and fiber got from coconut. The composite was prepared using hand layup process and sufficient precaution has been taken to ensure there is homogeneity. The composite is composed of 60% epoxy resin, 10% glass fiber and 30% coconut fiber. Various mechanical tests like micro hardness test, tensile strength, impact strength test has been carried out to characterise the composite. The various mechanical properties like density, micro hardness and tensile strength are affected when the coconut fibers were added. The impact strength and flexural strength of the composite increases while ultimate tensile strength decreases. The study has come up with prospective results and further research has to be done to examine the effect of fiber content, fiber orientation, loading pattern etc. Studies on corrosive wear and other tribological properties can reveal newer things, which can enable us to use the composite that is combination of epoxy and coconut fibers in newer and newer applications.

This research work is mainly focused on to study microstructure and mechanical properties of nickel reinforced aluminum 7075 alloy composites by equal-channel angular pressing (ECAP) process and ultrafine grained (UFG) of nickel reinforced aluminum 7075 alloy composites. The composites were prepared using liquid metallurgy technique. The content of nickel in the composition was varied from 2 to 8% (by weight) in steps of 2%. The ECAP processing was carried out using die with an intersecting channel angle of 120°. X-Ray Diffraction Technique (XRD) was used to confirm the percentage of reinforcement of in the composites. This study shows that severe plastic deformation has significantly improved the mechanical properties of nickel reinforced aluminium 7075 alloy composites compared to an alloy. Hardness test confirms that there is an increase in hardness for ECAPed samples at 8wt. % Ni and is 11% increase as compared to ECAPed pure Al7075 alloy and 40% compared to Non ECAPed 8wt. % Ni sample.

Aluminium as matrix in particular have been vastly investigated, this is because of the diverse applications of aluminium due to its excellent properties. Material scientists always face a challenge when it comes to the tribological and mechanical properties of aluminium, as it exudes quite poor behaviour in these aspects. Hence this work aims to improve the mechanical and corrosive resistance of Aluminium by reinforcing with Silicon Carbide and Nickel through powder metallurgy technique. Al-Ni-SiC composite with percentage of Ni fixed at 4% and SiC varied through 2-8% in increments of 2% were fabricated via powder metallurgy technique. The Optimized Load of 210kN and 560°C sintering temperature was used in the technique. The hardness value of the aluminium matrix composites improved with increased percentage of SiC, maximum increase was obtained for 8% SiC composite, showing an increase of about 87%. The wear resistance property of the prepared composites improved significantly with the increased percentage of SiC. There was anoticeable improvement in the corrosion resistance of the aluminium composites compared to its purest form, due to the presence of Ni. However, the increase in SiC percentage decreased the corrosion resistance. The maximum increase was obtained for 2% SiC composite, with an increase of 18.2%

Fiber reinforced plastics (FRP) products are light weighing and strong. These materials find extensive applications in various engineering fields and also as sensor metarial. Curing of this resin is a key to obtain FRP Products. Various factors including Gel time (Tgel) and peak exothermic temperature (Tpeak) are the critical factors that directly affect the curing process. Tgel is the indicator for the commencement of setting (polymer cross-linking) while Tpeak talks about the shrinkage and cracking of the polymer. This research work finds the Tgel and Tpeak for the curing of UP resin based isophthalic acid. The Catalyst MEKP (methyl ethyl ketone peroxide). The accelerator cobalt octoate (Cost) were used for the curing process. Results showed strong interactions between the process variables mentioned above. The process was anoptimization to achieve a combination of Tgel and Tpeak within the regime of experimentation. Mathematical models were developed using regression for both peak temperature and gel time. Confirmatory experiments were performed to validate the predicted results.

In the present study the effect of sliding speed on wear behaviour of as-cast and heat treated Aluminum alloy/composites has been investigated. Aluminum alloy series A356 is used as matrix, Silicon Carbide particles (SiCp) and graphite (Gr) particles are used as reinforcements. The proposed Aluminum Metal Matrix Composites (AMMCs) were fabricated by stir-casting. In the Aluminum A356 matrix, the reinforcement SiCp was varied from 0 to 9% by weights in steps of 3%, in addition to it 3% by weight Gr particles was also added. The castings were machined as per ASTM standard and T6-heat-treatment was carried out. Specimens were aged at different durations of 3, 6, 9, and 12hrs at a temperature of 155° C. The pin-on-disc wear testing machine was used to evaluate the wear rate of the composites. The results revealed that by increasing the reinforcement and ageing at T6-9hrs showed a maximum wear resistance in all the sliding tests. The reinforcements were restricted to 9% by weight due to the formation of agglomeration. The increase in sliding speed showed an increase of wear rate. The wear tested samples were examined for microstructure using scanning electron microscope (SEM) and the composition of worn out surface was confirmed using energy dispersive spectrum (EDS).