Wear Resistance Of Fly Ash Reinforced Aluminum Matrix Composite By Powder Metallurgy

Fly-ash is a solid waste product by thermo-power plants, it is cheap and easily found everywhere. The fly-ash possesses the shape of sphere and it is pay attention to as a kind of reinforcement, until now, the widely used method for fabricating particle-reinforced Al composite is stirring cast process, but its uniformity and the interface and the metal matrix is difficult to control and optimize.In this paper,99% purity aluminum as the basic raw materials as an additive to fly ash, through the uniform mixing of the powder-the uniaxial cold pressing-sintering process preparation of fly ash reinforced aluminum matrix composites. The study optimized the processing parameters to improve the dispersibility of fly ash; impacts of the pressing time on green samples were also be investigated; moreover, we researched the sintering temperature and time influence on density, hardness, interfacial properties and wear resistance. The results show that:Fly ash under the 300 mesh sieve was used as the reinforcing material; steel ball was used as grinding media, the appropriate diameters and proportion were W14:W12:W10:W8:W6=1:1:3:3:2; the mixing powder addition of milling pot was 150g, and the limiting speed was 140 r/min; When the mixing time of less than three hours, with the increase of mixing time, the dispersion of fly ash is improved, when the mixing time is more than three hours, the dispersion of fly ash will be strip among aluminum particles; and it can not enhance the uniformity with mixing more time; With the increase of fly ash content, the composites organizations are increasingly loose, in the current process, to ensure the fly ash content of less than 15% in the composite, the dispersion of fly ash content of more than 15%, the sample is difficult to be compact structure.90g mixing powder was used a 400MPa single axial compression in the powder compaction process for a high density, Maintaining a 2,4,6-minute pressure-holding time can emerge cracks in samples, but prolong of maintaining time, the integrity of samples is increased, and not easy craze.The hardness and wear resistance are enhanced with the sintering temperature elevated, the porosity decreases and the interfaces between particles disappear gradually, while sintering at 577?, the interface boundaries are still visible, the hardness and wear resistance result in poor performance; When the holding time is prolonged in sintering, the porosity decreases, the interfaces between particles disappear, the hardness and wear resistance are improved, but if it extend to 2.5 hour, the results show bad interface bonding, hardness and resistance; and sintering at 477?-holding 2 hour, can obtain excellent hardness and wear resistance.