Materials Science Forum Vol. 969

Abstract: Zinc aluminum based matrix composites reinforced with SiC and Al₂O₃ particles have significant applications in the automobile field. Stir casting method followed by squeeze process was used for fabrication. ZA27 composites reinforced with SiC and Al₂O₃ particles (20-50µm) in various weight percentage (wt%) ranges from 0-10 in a step of 5 each was fabricated. OM, SEM and EDS analysis of microstructures obtained for matrix alloy and reinforced composites were performed in order to know the effect of varying wt% on physical and mechanical properties of composites. Squeeze casting technique shows better features such as fine microstructure as a result of low porosity and good bonding between matrix and reinforcement. Addition of reinforcements decreased the densities of matrix alloy. SiC reinforced composites showed better results as compared with Al₂O₃ reinforced ones. Hardness and ultimate tensile strength value of 10 wt% reinforced composites showed improved results.

Abstract: Structural health monitoring (SHM) and damage detection techniques have recently gained attention in various fields of engineering for preventing catastrophic failures. Among different SHM techniques, Lamb wave propagation methods are widely used as these waves can propagate large distance from a single source. Piezoelectric (PZT) transducers are used here as actuators and sensors to generate and receive wave signals. Most of the studies conducted on wave propagation in plates are by use of conventional d₃₁ mode piezoelectric transducer. However, so far very few studies have been done using other types of PZT transducers. The primary objective of this paper is to determine and study the wave responses in a thin plate using different types of PZT transducers. The results indicate that the d₃₁ and d₃₃ type transducers generate Lamb waves, whereas d₂₄ and d₁₅ type transducers generate shear horizontal waves in two orthogonal directions. The study indicates that each of the transducers has its own directional property. The present study will be helpful for the application of Lamb waves and shear horizontal waves in plate structures

Abstract: This paper investigates erosive wear properties of carbon-epoxy polymer composites. Hand layup technique was employed to fabricate the composite specimens. Sand erosion properties of carbon/epoxy polymer composites were examined by changing testing parameters such as varying angle of impact (30⁰,45⁰,60⁰ and 90⁰), velocity of impact of sand particles (48m/s and 70m/s) and Stand-Off distance (5mm and10mm); and also by changing composite processing parameters such as fiber volume (20%, 25%, and 30%) and fiber orientation (30⁰,60⁰ and 90⁰). Irrespective of fiber volume and fiber orientation, rate of erosion shows increasing tendency, with increase of impact velocity. It was observed that with increase in fiber volume, erosion rate increases and where fiber orientation is concerned, increase of fiber orientation leads to increase in erosion rate. Irrespective of fiber orientation and fiber volume, Increase of Stand-Off distance leads to decrease in erosion rate. Finally the eroded surface morphology was observed by using SEM.

Abstract: The application range of natural fiber composites are increasing rapidly in several engineering areas. Unidirectional short castor oil fiber reinforced epoxy composites are fabricated using hand layup process with 40 vol% and 5mm length. Dry sliding wear tests are conducted using pin on disc tribometer. Applied loads are 15, 30 & 45N and track diameters were kept at 100, 110 and 120mm to achieve sliding distances of 1000, 2000 and 3000m respectively with adjustment of running times 6.5, 12 and 16 minutes at speed of 500 RPM. Full factorial DoE is employed and influence of each parameter on amount of wear, CoF and temperature are studied using ANOVA. It is found that load is the highly influential factor affecting amount of wear, CoF and temperature followed by sliding distance and other factors. Also, regression models are developed with good fit. The developed models predicted the results with 0-8 % error.

Abstract: The research article aims to study the impact and thermal sensitivity of pyrotechnic compositions which contain potassium perchlorate (KClO₄), aluminium (Al) and graphite (C). Simultaneous DSC-TGA (Differential Scanning Calorimetry and Thermogravimetric Analysis) were used for studying the thermal sensitivity, and BAM fall hammer was used for studying the impact sensitivity. The onset temperature of the exothermic reaction is between 521°C to 528°C for all the studied compositions. The lowest onset temperature of 521°C and limiting impact energy of 16.67 J were found for the composition containing 64% of potassium perchlorate (KClO₄), 33% aluminium (Al) and 3% graphite (C). The highest exothermic energy of 936 J/g was released for pyrotechnic composition consisting of 72% potassium perchlorate (KClO₄), 25% aluminium (Al) and 3% graphite (C), which is close to the exothermic energy release of 910 J/g for pyrotechnic composition consisting 64% potassium perchlorate (KClO₄), 33% aluminium (Al) and 3% graphite (C). Potassium chloride (KCl) was generated after the exothermic reaction, which was confirmed from the endothermic peak at around 773°C.

Abstract: In the present work, polystyrene composites using wheat husk, rice husk and mustard husk as fillers are synthesized using in-situ polymerisation technique. Three different filler loading (5%, 10% and 15 %) and three different filler sizes (250-355 µ, 355-500 µ, 500-710 µ) were utilized for the studying the effect of these compositions on different mechanical properties of the synthesized composites. The results have shown that the filler size 250-355 µ and 5 % loading give the maximum values for tensile strength, flexural strength and hardness for all the three types of fillers. While in case of water absorptivity lower the size/loading, lesser would be the water absorbed. The SEM analysis is done to study the fractured surface of the specimen.

Abstract: In this work, an attempt is made to find out the difference in erosion resistance of bidirectional (fibre orientation in 0° and 90° only) and multidirectional (fibre orientation in 0°, 15° 30°, 45°, 60°, 75°, and 90°) glass fibre epoxy composites. The erosion rate of the composites at different sand impingement angles (30°, 45°, 60°, and 90°) and at different velocities (86.57m/s, 101.15m/s, and 119.2m/s) was observed. The maximum erosion rate was observed at 45° sand impingement angle for both bidirectional and multidirectional composites. The orientation of the fibre in the composite has very little significance on the erosion rate. Both the composites with unidirectional and bidirectional glass fibre showed semi ductile behaviour. SEM was used to examine the surface of the specimen subjected to erosion. Erosion tendency with impact angle and fibre orientation was also touched upon in the study.

Abstract: Aluminium matrix composites (AMCs) are indispensable materials used extensively in the aerospace and automobile industries and are highly endorsed due to their good mechanical properties. In this paper, various compositions of the AMCs were fabricated, tested and analyzed using pin on disc tribometer test to understand the tribological behaviour and wear mechanism properties. The volume percentages of the Aluminium composite reinforced with boron carbide and graphite present in the form of Al-B₄C-Graphite are Al-B₄C (5%)-Graphite (5%), Al-B₄C (10%)-Graphite (5%), Al-B₄C (5%)-Graphite (15%), Al-B₄C (10%)-Graphite (15%), Al-B₄C (15%)-Graphite (15%). Loads were varied in steps of 10N, from 10N to 50N while the sliding velocity was correspondingly set as 0.7, 1.4 and 2.1m/s. SEM image analysis was conducted to understand surface tribology after wear tests. The composite Al-B₄C (15%)-Graphite (15%) exhibited best wear resistance which can be credited to the bearing capacity of boron carbide particles and adherent graphite layer.

Abstract: In this paper, the effect of size variation of cadmium sulphide nanocrystallites which have been prepared by precipitation method is analyzed. These prepared samples were studied using X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Energy dispersive analysis of spectroscopy (EDAX) techniques. SEM analysis represents the morphological nature of prepared samples and EDAX indicates the confirmation of elements present in the sample. XRD analysis determines the size of the samples and identifies the structure using miller indices (h k l values) of the nanocrystallies matches with JCPDS. From the XRD analysis, the size variation which depends on dopant, capping agent are discussed and corresponding results are reported in this paper.

Abstract: This paper is intended to find the corrosion behavior of carbon fiber reinforced Plastics (CFRPs). Some of the corrosion parameters such as 3.5% of NaCl, current density and voltage were taken into consideration. They were examined by potentiostatic polarization and scanning electron microscopy to find the corrosion rate of the CFRPs. The experiments were done by applying different voltages to the CFRPs and the corresponding current obtained will denote the corrosion rate. Based on the corrosion rates observed, the better combination can be selected in order to eliminate corrosion.