Influence of alumina particles preparation with nickel on aluminium matrix composite properties
Anita Olszówka-Myalska Politechnika Śląska, Wydział Inżynierii Materiałowej i Metalurgii, ul. Krasińskiego 8, 40-019 Katowice
Annals 2 No. 4, 2002 pages 199-203
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abstract The influence of a nickel coating deposited on Al2O3 particles on aluminium matrix composite properties was examined. For the production of the coating, an electroless method was applied. The 1 µm thick coating was characterized by good adherence to the substrate and uniform coverage, which is particularly important in places of a developed area (Fig. 1). The materials were produced in a Degussa press, as a result of uniaxial pressing in 2.6 Pa vacuum. Two sintering stages were applied - first stage under 1.5 MPa pressure, at a temperature of 400oC, for 30 minutes; second stage under 15 MPa, at a temperature of 640oC, for 50 minutes. Two types of composite sinters with an aluminium matrix were obtained, reinforced with nickel coated Al2O3 particles (20% vol.) with 500 mesh granulation, without additional preparation as well as a sinter of aluminium powder without reinforcement. Hardness measurements were carried out by means of Brinell method as well as a compression test, on the basis of which a conventional yield point and Young’s modulus were determined. The measuring system used at the compression test is presented in Figure 2. Table 1 shows the results obtained. A growth of the composite’s mechanical properties was found, caused by particles preparation. The applied nickel coating caused both a change of the matrixparticle interface structure and a change of the chemical composition of the matrix [8]. Wear tests of the examined materials were performed by Schopper method. The results are presented in Figure 3. The condition of the materials’ surfaces after the abrasion test, observed by means of SEM, is presented in Figures 4-6. Higher relative abrasive wear of the composite with nickel modified particles was found compared to the composite with nonmodified particles. After the wear test, in the composite with particles modified with nickel microcracks in the matrix were found on the surface.