Effect of fly ash particles on the mechanical properties of aluminium casting alloy A535

Abstract

Fly ash is a lightweight coal combustion byproduct (CCB) which is separated from the exhaust gases of power generating plants using suspension fired furnaces in which pulverised coal is used as the fuel. Its physical and chemical properties make it a useful construction and industrial material, especially in cement manufacturing, concrete, liquid waste stabilisation, and hydraulic mine backfill. The addition of fly ash into aluminium alloys has the potential to reduce the cost and density of aluminium castings while improving other physical and mechanical properties of the resulting metal matrix composites (MMCs). In the present study, the effect of fly ash addition on the mechanical properties of aluminium casting alloy 535 (A535) was investigated by means of hardness measurements, tensile testing, Charpy impact testing, optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), and X-ray fluorescence spectroscopy (XFS). The unreinforced A535 and its MMCs containing a mixture of 5 wt-% fly ash and 5 wt-% silicon carbide, 10 wt-% fly ash and 15 wt-% fly ash were investigated in the as cast and heat treated conditions. The results show that increasing the fly ash content of the melt increased the porosity of the castings, which ultimately affected the tensile and impact properties of the MMCs. The microhardness, tensile strength and Charpy impact energy of the composites decreased with increasing fly ash content. The loss in mechanical properties and impact resistance of the MMCs is attributed partly to the depletion of solid solution strengthening magnesium atoms from the matrix and partly to porosity.

Effect of Fly Ash Addition on the Physical and Mechanical Properties of AA6063 Alloy Reinforcement

“…The increased porosity of cast aluminum composites with increased fly ash content have also been reported by other researchers [29,35,36]. The porosity formation in the composites can be attributed to the increased content of the fly ash particles, which can lead to an increase in the porosity percentages of samples.…”

“…Gikunoo et al studied the influence of adding fly ash on the mechanical properties of 535 aluminum casting alloy. The results show that the increasing fly ash content of the aluminum composite increased the brittleness and porosity of the casted samples, which affected and decreased Charpy impact strength of aluminum/fly ash composites [29].…”

“…The porosity levels of cast composites were measured and chosen to be in the range of 2-4%. These porosity levels were slightly elevated due to the composite slurries still having gas and the casting having been carried out in the open atmosphere but could be considered reasonable due to casting conditions [29,43,44]. influence the increase in the porosity of composites was insufficient to explain the gaps between adjacent ash particles due to expected increases in the effective viscosity of casting melts resulting in a higher gas holdup [40] and improper feeding of liquid metal [37].…”

Fabrication, Charecterization and Development of High Damping Materials for Naval Applications

“…In both the above cases, the strength of the bond between the matrix and the particle is expected to play a critical role in determining wear. E. Gikunoo [2] reported that the presence of stress relieving cracks reaffirms the brittle nature of A535 alloy. Also, increasing the flyash reinforcement leads to a more brittle material.…”

Effect of fly ash reinforcement on the corrosion behaviour of cast Al-Mg alloy A535 in 3.5 wt% NaC1 solution

“…Although they have found potential applications in weight-critical components in automobile, aerospace, and defence systems [2][3][4][5], the application base of these particulate MMCs is limited by their high production cost. Recently, inexpensive aluminum alloy MMCs reinforced with fly ash, a waste by-product of coal combustion, has been engineered [6][7][8][9][10][11] to serve as a substitute for conventional particulate MMCs in several applications in order to widen the application bases of this class of MMCs. The addition of fly ash into aluminum MMCs is a value-added initiative that lowers the disposal cost of fly ash, increases energy savings by reducing the quantity of aluminum produced, and creates a healthier environment.…”