Investigation on Tribological Behaviour of Aluminosilicate Reinforced AA7075 Composites for Aviation Application
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ORIGINAL ARTICLE
Investigation on Tribological Behaviour of Aluminosilicate Reinforced AA7075 Composites for Aviation Application P. S. Samuel Ratna Kumar1
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Mashinini Peter Madindwa1
Received: 3 April 2020 / Accepted: 19 October 2020 Ó The Indian Institute of Metals - IIM 2020
Abstract In this study, AA 7075 and its composites were developed using ex situ (stir casting) process for varying compositions 1–3 in weight fraction (wt%) of aluminosilicate (nanoclay) at an interval of 1 wt%. The developed alloy and its composites have undergone T6 heat treatment condition. As per the ASTM standard G99-95, tribological study of the developed alloy and its composites were performed using pin-on-disc equipment under ambient temperature. The composites with 1 and 2 wt% of nanoclay showed increase in wear resistance compared to matrix material with mild wear. Coefficient of friction (CoF) value increased by addition of nanoclay compared to matrix material, due to applied load and sliding speed. To understand the wear mechanism, worn specimen’s surface morphology were examined using field emission-scanning electron microscope (FE-SEM). Further addition of nanoclay above 2 wt% showed some severe wear, cluster formation and poor bonding of nanoclay into the matrix material. Hardness value increased at 1 and 2 wt% of nanoclay and decreased at 3 wt% due to the improper bonding with matrix material. Reinforcement of nanoclay particles with 1 and 2 wt% reduced the wear rate and improved the durability of the matrix material. AA7075 (T6) material showed that it has suffered from abrasive wear mechanism. Also, nanocomposites showed the oxidation and adhesive as a dominant wear mechanism.
& P. S. Samuel Ratna Kumar [email protected] 1
Department of Mechanical and Industrial Engineering Technology, University of Johannesburg, Johannesburg, South Africa
Keywords AA7075 (T6) Nanoclay FE-SEM Wear Coefficient of friction (CoF)
1 Introduction Aluminium (Al) and its alloys are widely used in aerospace and defence applications due to its excellent specific strength, high resistance to corrosion, low density, ease to produce and provides better thermal stability to the material [1, 2]. In the field of tribological applications, the use of aluminium alloys is less due to poor resistance to wear. This leads to the way of discovering an aluminium metal matrix composites (AMMC) reinforced with discontinuous micro- or nano-material with improved mechanical, corrosion and wear resistance properties [3–5]. The AMMC reinforced with micro- or nano-material acts as a primary load bearing element, which leads to improved wear resistance and defend the metal soft surface against the hard surface to avoid wear [6, 7]. Compared to all aluminium alloy series, AA7075 (7-series Al–Mg–Zn–Cu) material is commonly used in aircraft applications due to high fatigue resistance, compressive strength, fracture toughness and strength to weight ratio [8]. AA7075 are the prime material for structural aircraft components like fuselages, wings and bols
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