MECHANICAL AND TRIBOLOGICAL BEHAVIOUR OF Al7075 – Al2O3 COMPOSITES
Keywords:
Al7075- Al2O3 composites, Density, Wear resistance, Mechanical propertiesAbstract
Aluminum alloys are light and are preferred for automobile, aerospace and mineral processing industries. These materials suffer with lower strength, hence they are reinforced with hard phase material, so as to modify their properties and to tailor them for required high performance application, and such reinforced materials are popularly known as composites. The ceramic reinforcement such as Al2O3, TiC, and SiC finds much importance in these Metal Matrix Composites (MMCs) for various automotive engine components, such as cylinder blocks, pistons and piston insert rings, brake disks and calipers. Thus, the tribological and mechanical properties of Al-alloy ceramic filled MMCs are of much interest. Hence the present paper aims at presenting experimental data on the above properties. The Al7075 reinforced with Al2O3 particulate were the composites prepared by liquid metallurgy route. 2-6 wt. % of Al2O3 were dispersed in steps of 2 to obtain the castings of composites. The cast composites were carefully machined to obtain the required test specimens as per ASTM standards for density, hardness, mechanical, tribological tests and microstructural studies.Hardness of the composites was measured using Vickers micro-hardness tester. The composites weight to volume ratio was the density. Lobo make metallurgical microscope attached with Pentax camera was used to obtain optical microphotographs. The mechanical properties were evaluated using a UTM of 20-ton capacity. Computerized pin on disc wear tester of Magnam make with EN31 counter steel disc (HRC60) was used for the evaluation of tribological properties. The microstructural studies revealed the uniform distribution of the particles in the matrix system, the measured density of the composites were found in line with that of the calculated by rule of mixtures, hardness of the composite was found to increase with increased filler content, the dispersion of Al2O3 in the Al7075 alloy confirmed the enhancement of mechanical properties and wear resistance.
Downloads
References
Y. Reda, R. Abdel-Karim and I. Elmahallawi “Improvements in mechanical and stress corrosion cracking properties in Al-alloy 7075 via retrogression and reaging” Materials Science and Engineering: A, 485, 468-475, 2008.
R. Clark, Jr, B. Coughran, I. Traina, A. Hernandez, T. Scheck, C. Etuk, J. Peters, E.W. Lee, J. Ogren and O.S. Es-Said “On the correlation of mechanical and physical properties of 7075-T6 Al alloy Engineering Failure Analysis”, 12, 520-526, 2005
S. W. Kim, D. Y. Kim, W. G. Kim and K. D. Woo “The study on characteristics of heat treatment of the direct squeeze cast 7075 wrought Al alloy” Materials Science and Engineering A, 304-306, 721-726, 2001.
V. Bystritskii, E. Garate, J. Earthman, A. Kharlov, E. Lavernia and X. Peng “Fatigue properties of 2024-T3, 7075-T6 aluminum alloys modified using plasma-enhanced ion beams Theoretical and Applied Fracture Mechanics”, 32, 47-53, 1999.
B. Venkataraman, G. Sundararajan “Correlation between the characteristics of the mechanically mixed layer and wear behaviour of aluminium, Al-7075 alloy and Al-MMCs” Wear, 245, 22-38, 2000.
T. Miyajima, Y. Iwai, “Effects of reinforcements on sliding wear behavior of aluminum matrix composites”, Wear 255, 606–616, 2003.
S. Kumar, V. Balasubramanian, “Developing a mathematical model to evaluate wear rate of AA7075/SiCp powder metallurgy composites”, Wear, 264, 1026-1034, 2008.
Rupa Dasgupta and Humaira Meenai “SiC particulate dispersed composites of an Al–Zn–Mg–Cu alloy: Property comparison with parent alloy” Materials Characterization, 54, 438-445, 2005
.9. T. J. A. Doel and P. Bowen “Tensile properties of particulate-reinforced metal matrix composites”, Composites Part A: Applied Science and Manufacturing, 27, 655-665, 1996.
K. Komai, K. Minoshima and H. Ryoson, “Tensile and fatigue fracture behavior and water-environment effects in a SiC-whisker/7075-aluminum composite”, Composites Science and Technology, 46, 59-66, 1993.
M.D. Bermudeza, G. Martinez-Nicolas, F.J. Carrion, I. Martinez-Mateo, J.A. Rodriguez, E.J. Herrera, “Dry and lubricated wear resistance of mechanically-alloyed aluminium-base sintered composites”, Wear 248, 178–186, 2001.
M.R. Rosenberger, C.E. Schvezov, E. Forlerer, “Wear of different aluminum matrix composites under conditions that generate a mechanically mixed layer”, Wear 259, 590–601, 2005.
L.J. Yang “A test methodology for the determination of wear coefficient” Wear 259, 1453–1461, 2005.
J.M. Wu, Z.Z. Li, “Contributions of the particulate reinforcement to dry sliding wear resistance of rapidly solidified Al-Ti alloys”, Wear 244, 147–153, 2000.
M.D. Bermudez, G. Martinez-Nicolas, F.J. Carri0n, I. Martinez-Mateo, J.A. Rodriguez, E.J. Herrera, “Dry and lubricated wear resistance of mechanically-alloyed aluminum-base sintered composites”, Wear 248, 178–186, 2001.
L.J. Yang, “Wear coefficient equation for aluminium based matrix compo Al2O3 sites against steel disc”, Wear 255, 879–892, 2003.
