PSI - Issue 27
Hammar Ilham Akbar et al. / Procedia Structural Integrity 27 (2020) 62–68 Akbar et al. / Structural Integrity Procedia 00 (2019) 000 – 000
66
5
2.7
2.65
2.6
2.55
g/cm³
2.5
2.45
2.4
Al6061-Sea sand Al6061-Alumina Al6061-SiC
Fig. 4. The density of composite.
0 1 2 3 4 5 6 7 8 Al6061-Sea sand Al6061-Alumina Al6061-SiC %
Fig. 5. Porosity of the composite.
3.3. Hardness The addition of reinforcing particles to the matrix increases hardness. A comparison of the hardness of each reinforcing particle is shown in Fig. 6. Composite hardness increased from 48.11 BHN to 119.6 BHN in the addition of 6%wt sea sand particle. On the addition of 6%wt of alumina composite hardness particles increased 4.75% compared to the matrix, then on the acquisition of 6%wt of SiC composite hardness particles increased 7.88%. Composite hardness increases due to the addition of SiC and alumina ceramic particles, which are harder than the aluminum matrix (Kumar et al., 2013). This phenomenon is matching with previous work (Gireesh et al., 2018; Terada et al., 2014). The addition of sea sand particles also increases hardness due to SiO 2 oxide compounds in sea sand particles, which have a higher hardness than the aluminum matrix (Hilman et al., 2014). The presence of particles on the composite causes the Orowan’ s mechanism (Srivastava and Chaudhari, 2018). The particles are limiting the movement of dislocation that increasing the hardness of the composite (Rozhbiany and Jalal, 2019). The addition of sea sand particle to aluminum matrix has the highest hardness compared to alumina and SiC particles. It is consistent with the calculation of density and porosity. Better wettability by the matrix reduced the porosity that increasing hardness (Bihari and Singh, 2017; Hashim et al., 2001). Wettability by molten aluminum on alumina and SiC ceramic particles is more difficult due to the presence of a passive layer in the interface particles. This condition caused the bonding interface between particles, and the matrix is weak and decreases the mechanical properties of the material (Zulfia and Adyatma, 2013).
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