Goutam Sutradhar

Tribological Characterization of Stir-cast Aluminium-TiB2 Metal Matrix Composites

The present study considers friction and wear of aluminium matrix composites reinforced with TiB2 micro particles processed through the stir casting method rather than in-situ techniques adopted by earlier studies. Different weight percentages of TiB2 powders having average sizes of 5 - 40 micron were incorporated into molten LM4 aluminium matrix by stir casting method. The friction and wear behavior were studied for Al-TiB2 composites prepared according to specific dimensions by using a block-on-roller type multi-tribotester at room temperature. Normal loads of 25 - 75 N and rotational speed of 400 – 600 rpm were used for determination of friction and wear behavior. It is found that friction and wear decrease with increase in percentage of TiB2 reinforcement in the composite, while friction and wear increase with applied load and speed. Scanning electron microscopy studies the reveal presence of both abrasive and adhesive wear mechanisms with abrasive wear being predominant.

Tribological Performance Optimization of Al-7.5% SiCp Composites Using the Taguchi Method and Grey Relational Analysis

The present study considers an experimental study of tribological performance of Al-7.5% SiCp metal matrix composite and optimization of tribological testing parameters based on the Taguchi method coupled with grey relational analysis. A grey relational grade obtained from grey relational analysis is used as a performance index to study the behaviour of Al-7.5% SiCp MMC with respect to friction and wear characteristics. The tribological experiments are carried out by utilizing the combinations of tribological test parameters based on the L27 Taguchi orthogonal design with three test parameters, namely, load, speed, and time. The material Al-7.5% SiCp metal matrix composite is developed by reinforcing LM6 aluminium alloy with 7.5% (by weight) SiC particle of 400 mesh size (~37 μm) in an electric melting furnace. It is observed that sliding time has a significant contribution in controlling the friction and wear behaviour of Al-7.5% SiCp MMC. Furthermore, all the interactions between the parameters have significant influence on tribological performance. A confirmation test is also carried out to verify the accuracy of the results obtained through the optimization problem. In addition, a scanning electron microscopy (SEM) test is performed on the wear tracks to study the wear mechanism.

Friction Performance of Al-10%SiCp Reinforced Metal Matrix Composites Using Taguchi Method

The present paper considers the friction performance of Al-10%SiCp reinforced metal matrix composites against steel for varying tribological test parameters. The composite is prepared by stir-casting process using aluminium alloy LM6 being mixed with 10% silicon carbide by weight. The tribological tests are performed by varying applied load, sliding speed, and time. The friction performance is studied using plate-on-roller configuration in a multitribotester and optimized using Taguchi L27 orthogonal array. Analysis of variance (ANOVA) is performed to observe the significance of test parameters and their interactions on friction performance. It is observed that normal load and the interaction between normal load and speed influence the friction behaviour, significantly. The wear tracks are analyzed with the help of scanning electron microscopy.

Relationship between matrix-microstructure and mechanical properties of copper alloyed thin wall austempered gray cast iron (TWAGI)

Abstract In this investigation the characteristics of thin wall (3 mm thickness) castings of copper alloyed gray cast iron have been examined. The samples of the thin wall castings have been austempered isothermally thus the thin wall austempered gray iron (TWAGI) produced. The samples austenitizing at 927 °C (1700 °F), the samples have been austempered at 260 °C (500 °F), 285 °C (545 °F), 310 °C (590 °F), 335 °C (635 °F), 360 °C (680 °F) and 385 °C (725 °F) respectively for 1 h. As a result, these samples developed an ausferrite matrix and excellent mechanical properties. The microstructures of these samples TWAGI have been characterized through optical microscopy, scanning electron microscopy and X-ray diffraction analysis. The mechanical properties may be correlated with the volume fraction of austenite and ferrite and ferrite cell size in the ausferrite microstructure.

Microstructure and mechanical properties of copper alloyed austempered grey cast iron

ABSTRACT Austempered grey cast iron (AGI) has emerged as a major engineering material in recent years because of its attractive mechanical properties. The main aim of this investigation is to assess the mechanical properties of copper alloyed AGI. Alloyed grey cast iron specimens are subjected to austempering heat treatment at six different temperatures for four different time periods. The resulting microstructures have been evaluated and characterised by means of light microscope and scanning electron microscope and X-Ray diffraction analysis. The microstructural features of AGI such as austenite content and its carbon content have been also found to influence the hardness, tensile properties and elongation. Both duration of the austempering time and the austempering temperature affect the mechanical properties of AGI. The hardness, tensile strength and ductility initially increase, and thereafter it decreases on longer periods of austempering. On the other hand hardness, tensile strength decreases as increasing austempering temperature, while ductility increases. The best combination of hardness 380BHN and strength 332 MPa; observed at 927°C of austenitising and 260°C of austempering temperature for 60 min.

HIGH TEMPERATURE TRIBOLOGICAL BEHAVIOR OF STIR-CAST Al–TiB2 METAL MATRIX COMPOSITES

This study considers high temperature tribological behavior of Al-TiB2 aluminum matrix composites (AMCs) fabricated through stir cast method. Effect of operating temperature on wear and friction behavior is studied for four different weight percentages of reinforcements using a high-temperature tribo-tester over a temperature range of 50∘C–250∘C under normal load in the range of 25–75N. Surface morphology and wear debris are studied through scanning electron microscopy (SEM) images. Energy dispersive X-ray (EDAX) and X-ray diffraction (XRD) studies are performed to observe the wear mechanism at high temperature. Increase in the amount of reinforcement improves wear resistance of composites at all temperatures. Friction and rate of wear are found to increase with operating temperature. Formation of oxide layers and softening of the surface are found to play crucial role in controlling the tribological behavior of stir cast Al–TiB2 composites at high operating temperatures.

Wear Behavior of Al-SiC Metal Matrix Composite under various Corrosive Environments

This paper investigates the wear behavior under corrosive environments of LM6 based metal matrix composite reinforced with 5 wt% SiC prepared through the stir casting method. The experiments are carried out in a pin-on-disk tribotester varying five levels of normal load and sliding speed. The duration of each experiment is fixed for 30 minutes. Three environments viz. dry, deionised and dilute acid environments are considered to carry out the tribological tests. The composite exhibits slightly good wear resistance under low load and speed condition but weight loss increases as these parameters increases in all three environments. Maximum weight loss occurs in case of acid environment as it is more corrosive than dry and deionised environment. The wear surface of the composite is examined through the scanning electron microscopic (SEM) and energy dispersive x-ray analysis (EDX).

Wear performance optimization of stir cast Al-TiB2 metal matrix composites using Taguchi design of experiments

The present study outlines the use of Taguchi parameter design to minimize the wear performance of Al-TiB2 metal matrix composites by optimizing tribological process parameters. Different weight percentages of micro-TiB2 powders with average sizes of 5-40 micron are incorporated into molten LM4 aluminium matrix by stir casting method. The wear performance of Al-TiB2 composites is evaluated in a block-on-roller type Multitribo tester at room temperature. Three parameters viz. weight percentage of TiB2, load and speed are considered with three levels each at the time of experiment. A L27 orthogonal array is used to carry out experiments accommodating all the factors and their levels including their interaction effects. Optimal combination of parameters for wear performance is obtained by Taguchi analysis. Analysis of variance (ANOVA) is used to find out percentage contribution of each parameter and their interaction also on wear performance. Weight percentage of TiB2 is forced to be the most effective parameter in controlling wear behaviour of Al-TiB2 metal matrix composite.