Abstract
Aluminium metal matrix composites are widely used in the automobile industry due to their superior properties like high strength to weight ratio, high ductility and better corrosion resistance. In this study, the effect of naturally available and low-cost kaoline particles on the microstructural and mechanical behaviour of Al- SiC- Kaoline Hybrid metal matrix composite was investigated. Al-10 % SiC- X% Kaoline (X = 0, 2, 4, 6, 8) composite samples were fabricated through powder metallurgy technique by applying a compaction pressure of 350 MPa. The fabricated composite samples were subjected to Density, Hardness, Tensile and impact tests to study the mechanical behaviour of fabricated hybrid composite. The presence of SiC and Kaoline reinforcements was confirmed by using SEM and X-Ray Diffraction analysis. It was observed that the maximum ultimate tensile strength ( U.T.S ) and maximum Yield Strength ( Y.S) of the hybrid composite were found to be 263 MPa and 202 MPa for Al-10 %SiC-4 %kaoline reinforcement. The formation of the intermetallic compound such as Al2Cu was observed in XRD and SEM analysis for Al-10 % SiC-6 % kaoline and Al-10 % SiC-8 % of kaoline reinforcement which leads to decrease in the U.T.S and Y.S of fabricated specimens. The impact strength of Al-10 %SiC-8 % kaoline found to be decreased by 44.4 % compared to unreinforced Aluminium due to the presence of harder SiC and Kaoline reinforcements particles. To study the fracture mechanism, Scanning Electron Microscopy study was carried on the fractured tensile specimens which reveal that ductile fracture in unreinforced Al, Al-10 % SiC, Al-10 % SiC-2 % Kaoline due to the formation of dimples and brittle fracture was observed in Al-10 % SiC-4 % Kaoline, Al-10 % SiC-6 % Kaoline and Al-10 % SiC-8 % Kaoline due to the existence of cleavages and microcracks. The best suitable combination of mechanical properties was obtained at Al-10 % SiC-4 % Kaoline hybrid composite.
Highlights
Hybrid Aluminium metal matrix composites contain two or more reinforcement elements dispersed in the Aluminium matrix phase, finds application in fabricating brake calliper, piston and rocker arms in the automobile industry due to their superior properties like high strength to weight ratio, higher hardness, higher compressive strength and higher ductility[1,2]
Hybrid metal matrix composites were introduced to enhance the properties of composite material than with single reinforcement attributed to improved mechanical properties [12]
The incorporation of kaoline reinforcements of more than 4% causes the formation of agglomerations and clusters of Al2Cu which was identified in Fig. 6 (c,d) and the corresponding peaks shown in X-ray diffraction analysis (XRD) pattern of Fig. (5)
Summary
Hybrid Aluminium metal matrix composites contain two or more reinforcement elements dispersed in the Aluminium matrix phase, finds application in fabricating brake calliper, piston and rocker arms in the automobile industry due to their superior properties like high strength to weight ratio, higher hardness, higher compressive strength and higher ductility[1,2]. The incorporation of harder ceramic reinforcements into the softer aluminium matrix enhances the hardness and reduces the ductility of base matrix material [3,4,5]. The reinforcement material can be a discontinuous type (particles, whiskers and short fibers) or continuous type (fibers) Among these particle reinforced like oxides ( Al2O3, ZrO2, MgO), carbides ( TiC, SiC, B4C) and Nitrides ( BN, AlN) are widely used as a dispersed phase in aluminium matrix material [8,9,10,11]. An attempt has been made to reinforce Kaoline as secondary phase reinforcements in the Al matrix In this present work, Al-SiC-Kaoline HMMC was fabricated through powder metallurgy technique by varying the Kaoline percentage from 0% to 8% and the effect of kaoline on the mechanical properties like Hardness, Tensile strength, Impact strength are investigated. The fractured tensile samples were subjected to Fractography analysis to know the type of fracture that occurred in the fabricated samples
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