Wear Behaviour of Aluminium Based Metal Matrix Composites Reinforced With Red Mud, SiC and Al2o3

Abstract

Metal matrix composites are used mostly in space ships, aerospace, automotive, nuclear, biotechnology, electronic and sporting goods industries, but due to their high cost, experiments are usually done to reduce the cost of the composites and inexpensive materials are utilised for metal matrix composites. Red mud emerges as the major waste material during production of alumina from bauxite by the Bayer‟s process. It comprises of oxides of iron, titanium, aluminium and silica along with some other minor constituents. Based on economics as well as environmental related issues, enormous efforts have been directed worldwide towards red mud management issues i.e. of utilization, storage and disposal. Different avenues of red mud utilization are more or less known but none of them have so far proved to be economically viable or commercially feasible. It is generally agreed that micro hardness and resistance to wear of MMCs is created by reinforcement and also the wear properties are improved remarkably by introducing hard intermetallic compound into the aluminium matrix. The reinforcing materials are generally SiC, Al2O3, TiO2 etc and are costly. The present research work has been undertaken with an objective to explore the use of red mud as a reinforcing material due to its easy availability and contains all these reinforcement elements. In the present investigation a comparative study on abrasive wear behaviour of Aluminium metal matrix composite reinforced with Red Mud, SiC and Al2O3 (produced by the stir casting technique) has been carried out. During this investigation, Red Mud was received from CBRI, IIT Roorkee and SiC and Al2O3 was received from the market (local source). In this research, wear performance and microhardness studies were carried out by varying the percentage of reinforcements in the matrix. All experiments were conducted under room temperature condition. To assess the wear characteristics of the aluminium alloy 6061 with red mud, SiC and Al2O3 composites (in pure sliding mode) a computerized pin-on-disc machine was used. Microhardness tester was employed to measure the value of microhardness number (VHN) of different MMCs by indenting the diamond indenter on the specimen with a constant load of 200 gram and constant dwell time of 20 seconds at 10X optical zoom. The specimens were studied under optical microscope and SEM to get an idea about the distribution pattern of the reinforcement in the matrix alloy and effect of these particulate reinforcements on the wear behaviour and microhardness of the composites. Dispersion of particulates in aluminium matrix improves the hardness of the matrix material and also the wear behaviour of the composite. X-ray Diffraction (XRD) was performed to know the presence of the phases of reinforced material. There are other fabrication techniques available where the volume fraction of reinforcements could be increased and are likely to vary the wear performances of the composite. This work can be further extended to those techniques. However these results can act as a starting point for both industrial designers and researchers to design and develop MMC components using this industrial waste.