Investigation of Tribological Behavior of a Novel Hybrid Composite Prepared with Al-Coconut Shell Ash Mixed with Graphit
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IN materials development, many newer materials have been created to meet industrial challenges. Among these materials, metals and alloys occupy a key position. Attractive properties such as strength, toughness, resilience, thermal stability, conductivity, and formability have led to the wide spread use of metals and alloys in manufacturing. However, the limited solid solubilities among two or more metals have restricted their development.[1–5] Many new intermetallic compounds have been developed and utilized.[5–7] However, these compounds do not fulfill industrial or technological requirements. Composite materials, known for a long time, are now used widely to comply with custom requirements. By compromising the properties of the constituents in a composite, a new material can be achieved that meets the end-use requirements. The addition of two or more materials, without proportion restrictions, can help in preparing newer materials suitable for the desired use.
R. SIVA SANKAR RAJU, M.K. PANIGRAHI, and R.I. GANGULY are with the Department of Mechanical Engineering, Gandhi Institute of Engineering and Technology, Gunupur, Odisha, India. Contact e-mail: [email protected] G. SRINIVASA RAO is with the Department of Mechanical Engineering, RVR & JC College of Engineering, Guntur, Andhra Pradesh, India. Manuscript submitted February 1, 2017. METALLURGICAL AND MATERIALS TRANSACTIONS A
Hence, the 20th century saw the development of many new composites.[1–6,8] Materials for industrial use should possess higher specific strengths.[9,10] Therefore, major metal matrix composites (MMCs) are often prepared with lighter materials such as Al, Ti, or Mg as base metals.[11–13] Among these, Al is often used as a base material because it is cheap and abundantly available. It has good thermal and electrical conductivity, as well as good formability. Al alloys can be age-hardened because Al is partially soluble with other metals such as Cu, Mg, and Zn in minor quantities. For these reasons, Al is preferred for use in the defense, automobile, and aerospace industries.[14–16] For Al-matrix materials, the reinforcing agents are typically hard ceramics scattered in the matrix. Typical reinforcing agents include Al2O3, SiC, BN, and TiO2.[14,15,17–22] The properties of the composites depend on the chemical composition, volume fraction, size, shape, and distribution of the dispersive reinforcement phase. Fiber reinforcement has promoted attractive composite properties, but the production of ceramic fibers (i.e., SiC and Al2O3) is both difficult and costly.[16,19,23–25] Therefore, the use of fiber-reinforced MMCs is restricted to concerns such as defense, where cost is less of an issue. Fiber-based composites require sophisticated fabrication techniques, since the brittle ceramic fibers are usually damaged during processing.
To reduce the cost and ease production, Al-based composites can be prepared with fine powders of Al2O3/ SiC using the stir-casting method. However, some difficulties are encountered in producing Al-based composites be
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