Applied Mechanics and Materials Vols. 813-814

Abstract: Aluminium, being the second most abundant metal in earth’s crust, has emerged as an important metal in human civilization’s development. It has served as an excellent substitute for many conventional materials like wood, copper, iron and steel. Now a days, more Aluminium is consumed (on a volumetric basis) than all other non-ferrous metals/alloys including copper.Aluminium and aluminium alloy are gaining huge industrial significance because of their good combination of mechanical, physical properties over the base alloy. In some few recent years the use of metal matrix composite material increases very rapidly due to their high weight to strength ratio, low density, low thermal expansion coefficient, low maintenance and high temperature resistance. Metal matrix composites are widely used in aerospace and automotive engine components. The aluminum alloys are reinforced with Al₂O₃, B₄C and TiC and fabricated by stir casting, centrifugal casting, and powder metallurgy process. In the fabricated metal matrix composites some different tests were conducted to show mechanical properties, micro-structural characterizations of materials were also done. When composite subjected to heat treatments then it significantly affects the micro-structural developments of composite causing to relieving of stress.

Abstract: Carbon nanotubes are the latest trends in the study of powder metallurgy and nanocomposites. This is due to the exceptional properties like superior mechanical and electrical properties, high Young’s modulus, high tensile strength, smaller diameters, high elongation and high chemical stability. CNT’s is an attractive reinforcement for metal matrix composites. CNT are now reinforced with many metal matrix composites like aluminium, iron, manganese, copper etc. with considerable change in density of the material. Due to high aspect ratio that facilitates their tubular structure and high strength the CNT’s are reinforced with ferrous powder by implying powder metallurgy process and the results have been recorded. Such recordings of the effects of CNT on Ferrous powders are reviewed in this paper.

Abstract: In this study, new biodegradable composites were developed with loofah, jute and commercial E-glass as reinforcing fibers and poly ester as the resin. Loofah fibers are preheated with distilled water and alkali followed by heat treatment in order to enhance its surface properties. Four composite materials are prepared by varying the proportions of natural and glass fibers in each and maintaining the resin content as a constant. The specimens were subjected to testing of mechanical properties namely tensile strength, compressive strength, flexural strength and impact strength. The results revealed that the mechanical properties like tensile, flexural and impact strengths were high when proportions of all fibers are equal. Also, compressive strength was higher with sample containing only loofah fibers.

Abstract: In the present study, the corrosion behaviour of the Al2219, Boron carbide and Graphite has been investigated. The Aluminium Metal Matrix Hybrid Composites were fabricated by two step stir casting technique. Corrosion tests were carried out with the natural sea water (3.5 wt % NaCl) according to standard procedure. The tests were conducted at room temperature by cyclic polarization technique for a definite time interval. After the test, material loss was calculated by weight loss method. The surface morphology of the specimen before and after corrosion was studied using the optical microscope images. The test result reviles that, the corrosion rate of the composite was greater than the base alloy, but the corrosion of the hybrid composite is the most compared to the alloy and monolithic composite.

Abstract: In materials industries, composite is an emerging material known for its low weight - high strength. The composite is a material that contains two different phases in order to create particular properties. The synthetic composites require a large quantum of energy and also the environment is being affected due to the pollution generated during the production and recycling. This draws the attention to use natural fibers as it is lower in cost and biodegradable. In this work, the chemical treatments of the banana and abaca natural fibers are carried out to modify the surface, stop the moisture absorption and improves the adhesion. The chemical treatment is carried out for both fibers separately in 10% concentrated sodium hydroxide for a duration of five hours and 5% concentrated potassium permanganate for a duration of two hours. The composite materials are fabricated using treated fiber and untreated fiber individually with general polymer resin by the hand lay-up process. The fabricated composites are tested to evaluate mechanical properties such as tensile, impact and flexural strength as per the ASTM standards. The mechanical properties of the treated fiber and untreated fiber are compared and it is found that the mechanical properties have been significantly improved due to the chemical treatment.

Abstract: The influence of chitosan impregnation on the tensile and flexural strength of the short coir fiber reinforced polyester composites were studied in this investigation. The chitosan fillers were dispersed in polyester matrix, and laminates were prepared by reinforcing coir fibers in chitosan –polyester matrix. The composites were fabricated by varying filler content, fiber content and fiber length in three levels and their influence on tensile and flexural strength of the composites were studied. The composites with fiber length 30 mm, filler content 4% and fiber content 25% showed better values tensile (23 MPa) and at the same time the flexural strength (28MPa) of the composite was observed to be better with fiber length 30 mm, filler content 4 % and fiber content 25%.

Abstract: In this experiment, comparison analysis of mechanical properties, porosity and grain size of Pure Al (powder), 95%AL + 5% B₄C (With sand casting method) and 95%AL + 5% B₄C (With ECAP method) are determined. The ECAP method value is much greater than the sand casting method,because of metal matrix composite microstructure refinement during the pressing operation. Because of material porosity value decreases, powder particle consolidation, the closure of porosity, grain refinement and improve in dislocation occurs as ECAP method gives the results of Mechanical properties as like tensile strength 105.8Mpa, Hardness 94HV, density 888.88kg/m³values increase. At the same time, porosity and grain size value will be reduced because of individual power consolidation happening during ECAP methods like as 1.63% and 8μm. In this metal matrix composite is applied to aeronautical and automobile industry

Abstract: Materials added to the matrix help improving operating properties of a composite. In the last few years, nanofiller /polymer composite have been widely investigated because of their outstanding multifunctional properties. In order to improve the erosive wear resistance of composite, an attempt was made to use nanoTiO₂ and nanoclay as filler for the basalt reinforced epoxy composite (BE). The impact velocity, filler concentration and temperature are the parameters used for the study. The composites were fabricated using vacuum assisted resin infusion technique (VARI) technique. The fabricated composite specimens were tested by using erosive wear test rig as per ASTM G76 under normal incidence. The result shows that the erosion rate increases with increase in temperature and impact velocity. However, nanoTiO₂-filled BE composite exhibits lower erosion rate as compared to Nanoclay filled and unfilled composite. The morphology of eroded surfaces was examined by using scanning electron microscopy (SEM).

Abstract: In this study the lamina properties of glass/epoxy, carbon/epoxy and kevlar/epoxy composite along their principal coordinate axes were evaluated by performing tensile test. The laminates were prepared by hand lay-up technique and compressed using a compression molding machine at 70 ^oc and 80 bar pressure. The test was conducted as per ASTM standard D3039 by affixing strain gauges in the specimen to obtain the longitudinal and transverse strain. The mechanism of failure was also studied by performing fractographic analysis using scanning electron microscope which shows peeled off fiber surfaces in the case of kevlar/epoxy laminate.