Advanced Materials Research Vols. 984-985

Abstract: The fibers from naturally available resources are considered to have potential alternate reinforcing agent in polymer matrix composite materials due to their properties such as high strength, stiffness, degradable in nature and renewable in nature. In this study a lightweight, low cost and environment friendly hybrid composites are prepared by using sisal-jute-glass fibers as the reinforcement materials. There are three types of composites such as sisal/glass fiber reinforced polymer (SGFRP) composites, jute/glass fiber reinforced polymer (JGFRP) composites and sisal/jute/glass fiber reinforced polymer (SJGFRP) composites are prepared by hand lay-up process and underwent to charpy impact test in order to study their impact properties. Post impact induced damage, material failure mechanism, matrix cracking, fiber breakage and pullout was observed by using scanning electron microscopy (SEM) analysis. The results showed that the energy absorption and load carrying capacity of JGFRP composites are better and able to withstand higher loads than SGFRP composites and SJGFRP composites. It is further observed from the experiment, the inclusion of sisal and jute fibers with glass fiber reinforced polymer (GFRP) composites has gained good impact properties. It is suggested that these light weight sisal and jute fibers have been used as an alternative reinforcing material to synthetic fiber for medium load applications.

Abstract: Vibration damping is proving important for improved vibration control and dynamic stability in advanced engineering systems like aerospace systems, automobiles and in ship building industry. In the present investigation, vibration characteristics of woven fabric carbon composite plate reinforced with micro rubber particle blended into epoxy matrix is studied for enhancing the vibration damping performance. Test Specimens are fabricated in the form of hand layup method. CTBN rubber particle size of 5μm is selected and added to the epoxy matrix for fabricating carbon/epoxy composite plates. Rubber particles of 3% & 15 % by weight were considered as blended percentage in epoxy matrix and compared with 0% addition of rubber particles for understanding and analyzing the vibration characteristics and its difference in damping performance. Vibration damping and modal responses of various kinds of prepared plates were studied and compared. Among tested samples, carbon/epoxy composite plate with 15 wt % micro rubber particle by weight showed very good damping performance.

Abstract: Current work, aims at preparation and characterization of Al-Al₃Ti in-situ metal matrix composites with varying percentage of in-situ Al₃Ti (3 and 5%) reinforcement. The composites were prepared by the salt route involving reaction of commercial purity aluminum (99.7%) and potassium titanium flourate halide (K₂TiF₆) salt at a reaction temperature of 800°C and with 60min. holding time. The prepared composites were subjected to microstructural studies using Scanning Electron Microscope. Further, the work aims at evaluating mechanical properties of the prepared composites as per ASTM standards. Microstructural characterization using SEM revealed blocky morphology of Al₃Ti intermetallics with fairly homogeneous distribution. Insitu Al-Al₃Ti composites have shown better mechanical properties when compared to the unreinforced Al matrix.

Abstract: Polymer composites reinforced with natural fibers have been developed in recent years, showing significant potential for various engineering applications due to their inherent sustainability, low cost, light weight and comparable mechanical strength. Sisal is a natural fiber extracted from leaves of Agave Sisalana plants and substituted for natural glass fiber. Six different combinations of specimens were prepared with sisal, sisal-glass and glass fibers with epoxy as matrix at two different fiber orientation of 0-90° and ±45°. Mechanical characterization such as tensile, flexural and impact testing were done to analyze their mechanical strength. It is found that the hybrid composite sisal-glass-epoxy has better and comparable mechanical properties with conventional glass-epoxy composite and thus provides a viable, sustainable alternate polymer composite.

Abstract: In the present work, Taguchi method was employed to optimize tensile strength and hardness of the stir casted Al/RHA composite. The composites were prepared by varying stir casting parameters like stirring time (6, 9, 12 min), stirring speed (100,200,300 r.pm), and weight percentage of RHA reinforcement (6, 9, 12 %). All the experiments were conducted based on plan of experiments (L₉ Orthogonal array) generated through Taguchi Technique. The individual influence of each process parameters on the hardness and tensile strength was determined by using analysis of variance. The result implies that the wt. % of RHA reinforcement was found to be a highly influenced parameter followed by stirring time and stirring speed. Finally, confirmation test was done to verify predictive model with the experimental results.

Abstract: In this study, GFRP plates were friction stir processed at three different feed rates (15 mm/min, 20 mm/min and 25 mm/min) and at a constant spindle speed of 1500 rpm with an aim to enhance their microstructural properties. The friction stir processed plates were then subjected to milling with solid carbide K6 end mill tools. Millings trials were carried out using a Taguchi’s L9 orthogonal array under three input parameters such as cutting speed, feed and depth of cut each having three levels. The statistical significance of the process parameters was estimated using signal to noise (S/N) ratio and Analysis of Variance (ANOVA). The study showed that cutting speed during milling and feed rate during FSP contributed to the overall performance which was assessed in terms of surface roughness and delamination factor.

Abstract: Copper base composites are extensively used in applications where high temperature and corrosive environment. In the present investigation a hybrid metal matrix composite is prepared in which copper is used as a matrix, SiC and Fly ash as reinforcements. The composite is produced by powder metallurgy technique. Dry sliding wear characteristics of the prepared composite specimes were studied by pin on disc setup and optimised result was found through grey relational analysis. Analysis of variance is used to investigate the significance of design parameters which affect the wear characteristic of the materials. The results showed that sliding velocity is having the significant effect than the other parameters.

Abstract: Micro-TiO₂ and nanoTiO₂ dispersed Al 7075 composites have been synthesized by mechanical milling followed by cold compaction and sintering. The compressibility of the nanocomposites is less than the micro composite, but sintered density of the nanocomposite is higher that the microcomposite. Nanocomposite shows better hardness than microcomposite. However, both types of composites do not show artificial ageing characteristics like unreinforced Al 7075 alloy. Microstructural analysis through XRD and TEM reveals that the formation of MgTiO₃ and ZnO near TiO₂-Al 7075 matrix interface causes depletion of Mg and Zn in the Al 7075 matrix. This suppresses GP zone formation and shows almost no age hardenable characteristic. Potentiodynamic electrochemical polarisation study shows that the corrosion potential (E_corr) has shifted towards noble direction with the addition of TiO₂ in the composite.

Abstract: In the current investigation an attempt has been made and to produce ceramic Al₂O₃ particulate reinforced 6061Al matrix composites by liquid metallurgy route (stir casting technique) and to study the dry sliding wear properties of the prepared composites. The amount of ceramic Al₂O₃ particulate reinforcement addition was maintained at 9 and 12wt%. During the preparation of each composite the ceramic reinforcements were introduced in a novel way which involves three stage additions of reinforcements during melt stirring. The wear tests were conducted using pin on disc wear testing machine on 6061Al matrix before and after addition of Al₂O₃ reinforcements Wear test results demonstrated the superior wear resistance of the composites over monolithic 6061Al alloy matrix. Key Words: MMC’s, Al₂O₃ particulates, 6061Al, stir-casting

Abstract: Metal Matrix Composites possesses high mechanical properties compared to unreinforced materials. Aluminium Matrix Composites (AMC) is attracted in the emerging world because of its low cost, less weight and enhanced mechanical properties. In the present study the enhancement in mechanical properties like hardness and tensile strength of AMCs by reinforcing AA 6061 matrix with silicon carbide (SiC) and boron carbide (B4C) particles are analyzed. By enhanced stir casting method aluminium matrix was reinforced with boron carbide particulates and silicon carbide particulates with the various weight percentage of 2.5 %,5% and 7.5%.The tensile strength and hardness was found to increase with the increase in wt% of the reinforcement. From the analysis it is observed that the mechanical property of B4C reinforced AMC is significantly good compared to SiC reinforced AMC.