a b s t r a c t The corrosion and wear behaviour of Al–Mg–Si alloy matrix hybrid composites developed with the use of rice husk ash (RHA) and silicon carbide (SiC) particulates as reinforcements were investigated. RHA and SiC mixed in weight ratios 0:1, 1:3, 1:1, 3:1, and 1:0 were utilized to prepare 5, 7.5 and 10 wt% of the reinforcing phase with Al Mg Si alloy as matrix using double stir casting process. Open circuit corrosion potential (OCP) and potentiodynamic polarization measurements were used to study the corrosion behaviour while coefficient of friction was used to assess the wear behaviour of the composites. The corrosion and wear mechanisms were established with the aid of scanning electron microscopy. The results show that the effect of RHA/SiC weight ratio on the corrosion behaviour of the composites in 3.5% NaCl solution was not consistent for the different weight percent of reinforcement (5, 7.5, and 10 wt%) used in developing the Al–Mg–Si based composites. It was evident that for most cases the use of hybrid reinforcement of RHA and SiC resulted in improved corrosion resistance of the composites in 3.5% NaCl solution. Preferential dissolution of the more anodic Al–Mg–Si alloy matrix around the Al–Mg–Si matrix/RHA/SiC particle interfaces was identified as the primary corrosion mechanism. The coefficient of friction and consequently the wear resistance of the hybrid composites were comparable to that of the Al–Mg–Si alloy matrix reinforced with only SiC.

Corrosion and wear behaviour of Al-Mg-Si alloy matrix hybrid composites reinforced with rice husk ash and silicon carbide

The present research work reports the fabrication and evaluation of the mechanical properties of hybrid aluminium matrix composites (HAMC). Aluminium 7075 (Al7075) alloy was reinforced with particles of boron carbide (B4C) and coconut shell fly ash (CSFA). Al7075 matrix composites were fabricated by stir casting method. The samples of Al7075 HAMC were fabricated with different weight percentages of (0, 3, 6, 9 and 12wt.%) B4C and 3wt.% of CSFA. The mechanical properties discussed in this work are hardness, tensile strength, and impact strength. Hardness of the composites increased 33% by reinforcements of 12wt.% B4C and 3wt.% CSFA in aluminium 7075 alloy. The tensile strength of the composites increased 66% by the addition of 9wt.% B4C and 3wt.% CSFA in aluminium 7075 alloy. Further addition of reinforcements decreased the tensile strength of the composites. Elongation of the composites decreased while increasing B4C and CSFA reinforcements in the matrix. The impact energy of the composites increased up to 2.3 J with 9wt.% B4C and 3wt.% CSFA addition in aluminium alloy. Further addition of reinforcement decreased the impact strength of the composites. The optical micrographs disclosed the homogeneous distribution of reinforcement particles (B4C and CSFA) in Al7075 matrix. The homogeneously distributed B4C and CSFA particles added as reinforcement in the Al7075 alloy contributed to the improvement of hardness, tensile strength, and impact strength of the composites.

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Investigation on mechanical properties of aluminium 7075 - boron carbide - coconut shell fly ash reinforced hybrid metal matrix composites

Powder metallurgy processing of aluminum alloy based metal matrix composites (MMC) is realized to be a promising alternative as expected to advance rapidly compared to other conventional methods. This paper reviews the extensive development in metal-matrix composite research works with particular focus on aluminum alloys 2xxx series as metal-matrix particulates processed by powder metallurgy route. Effect of reinforcement materials such as SiC and Al2O3 on the mechanical properties of the composites manufactured through conventional methods and powder metallurgy route are compared and presented. The influence of percentage of reinforcement material on the overall properties of the MMC’s as reported by the researchers are presented. Summary on fundamental aspects of manufacturing MMC’s via powder metallurgy route, the effect of mechanical properties, tribological properties, and microstructural properties are presented. Eventually, some advantages of powder metallurgy method are mentioned which may substantiate the claim to consider this as a novel method for near net shape manufacturing.

Processing methods and property evaluation of Al 2 O 3 and SiC reinforced metal matrix composites based on aluminium 2xxx alloys

Hybrid composites with aluminum matrix and non-metallic reinforcements are identifying extensive applications in automobile, aircraft, and military industries due to their high strength-to-volume ratio, corrosion resistance, excellent machinability, wear resistance, high thermal conductivity, etc. Nanocomposite materials are usually selected for structural applications since they possess desirable association of mechanical properties. The hybrid metal matrix nanocomposite development has come to be the most crucial area of material science engineering. In the present study, the Al 7075 is reinforced with 1.0, 2.0, 3.0, and 4.0 wt.% of (Al2O3 + SiC) and 1 wt.% of magnesium (Mg) to manufacture the hybrid composite. Magnesium (Mg) is mainly used to increase the wettability of the nanocomposites. The present research is focused on determining the mechanical and wear properties of Al 7075 in the existence of Al2O3 (20–30 nm), SiC (50 nm), and magnesium (micro). The compositions are increased from 1 to 4 wt.%, and stir casting method are used for the fabrication of aluminum metal matrix nanocomposites. The mechanical characteristics of metal matrix composites such as tensile strength, compression strength, and hardness test are studied by carrying out experiments on the computerized universal testing machine and Vickers hardness equipment. The microhardness, compression strength, and tensile strength of aluminum 7075 alloy increases by incorporating Al2O3and SiC reinforcements. Wear analysis was done to examine the effect of SiC and Al2O3 ceramic particles using a pin on disc apparatus. Worn out areas of the specimens were analyzed by SEM, energy dispersive analysis X-ray (EDAX), and XRD analysis.

Mechanical and wear behavior of Al 7075/Al 2 O 3 /SiC/mg metal matrix nanocomposite by liquid state process

The use of agricultural wastes which is cost-effective and environmental-friendly materials as reinforcers in metal matrix composites is growing fast in various engineering fields. With this, the research investigates the mechanical, microstructure, and wear behaviors of Al-12%Si alloy reinforced with melon shell ash (MSA) for developing a new material. Melon shell ash of particle size of 50 μm was prepared for the studies. Different weight percentages of 5, 10, 15, and 20 MSA were used to develop metal matrix composites for the investigations. The melon shell ash was characterized by X-ray fluorescent (XRF). The morphology of the alloy and composites were studied using scanning electron microscope for the distribution of melon shell ash (MSA) particles. The XRF revealed some oxides with silica (SiO2) being the highest followed by potassium oxide (K2O), alumina (Al2O3). The results of the mechanical properties indicate that the tensile strength increased from 122.5 MPa in the alloy to 204.5 MPa in composites, the hardness values increased from 95 HRC to 103.1 HRC, the impact energies decreased from 17.5 to 14.0 J and percentage elongation also decreased from 35.3 to 16.0 respectively. The wear rate decreases from 0.022 to 0.0091 g/min. The microstructures revealed that the MSA was uniformly distributed within the composites and resulted to the appreciable increase or decrease in the mechanical properties which were attributed to the oxides present. The composites can be used in automobile industries where some of these properties can be explored.

Investigation of mechanical, microstructure, and wear behaviors of Al-12%Si/reinforced with melon shell ash particulates

The paper presents the results of experimental investigation on the characterization and analysis of mechanical properties of composites formed. Three aluminum metal matrix composites reinforced with 10 wt% of B4C, SiC and Al2O3 particles were processed. The stir casting method followed by hot rolling was used for fabrications of aluminium 7075 metal matrix composites, being one of the cost effective industrial methods. Experimental results show nearly a uniform distribution and good dispersion of reinforced particles within aluminium matrix. Both tensile strength and hardness are enhanced by incorporation of reinforcement particles into the matrix. Scanning electron microscope (SEM) analysis was done to study the good dispersion of particles and surface characteristics.

K. Keerthivaran

Papers

Fabrication and Characterization of SiC, Al2O3 and B4C Reinforced Al-Zn-Mg-Cu Alloy (AA 7075) Metal Matrix Composites: A Study