PSI - Issue 14

Vikas Verma et al. / Procedia Structural Integrity 14 (2019) 68–77 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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3.2 Mechanical properties

A systematic study of hardness, tensile and bending strength of pure Al alloy and composites is done as shown in Table 2. It is observed that addition of flyash and 12wt% of Al 2 O 3 in Al base metal matrix has resulted in improved mechanical properties. Hardness increased from 82 to 162 BHN, strength increased from 57 to 156 N/mm 2 and bending strength varied from 2.4 to 6 kN. Hardness and strength of the composite increased due to the addition of alumina particles. Alumina particles strengthens the matrix to resist deformation under load.

Table 2. Al-Al 2 O 3 and fly ash MMC’s processed via stir casting at 750°C temperature Composition (wt.%) BHN

Tensile strength (N/mm 2 )

Bending strength (kN)

Pure alloy

82.5 117.7 145.4 162.1

57.2 95.5

2.4 4.7 5.1 5.9

Al alloy +5%Fly ash +6%Al 2 O 3 Al Alloy+5%Fy ash+9%Al 2 O 3 Al Alloy+5%Fly ash+12%Al 2 O 3

107.2 156.2

3.3 Frictional behaviour/wear results

Figure 5 a,b,c shows the curves showing the relation between load v/s weight loss, time v/s weight loss, velocity v/s weight loss of pure Al alloy and composites. It is observed that the most dominating factor controlling wear behaviour is applied load. At varying load at constant speed and time, wear of Al composites increased with increase in load. Wear rate decreased with increase in weight percentage. Wear rates were less at low load and gradually increased with the increase in load as shown in Figure 5 (a). Varying time v/s weight loss graph (Figure 5 b) shows the wear rate of pure alloy is more compared to reinforced composites. Wear rate of composites and pure alloy specimens increased with increase in sliding time. Varying speed v/s weight loss graph (Figure 5 c) revealed as the speed increases the reinforcement particles undergo less fracture and it helps in retaining amount of reinforcement particles. These accumulated reinforcement particles influences the wear resistance with the increase in speed. Reinforcement particles are squeezed onto the surface by subsurface deformation and subsequent transferring results in formation of the lubricating film or tribolayer.