Influence of parameters of sintering under pressure process on selected properties of composite material Al-Al2O3 particles
Michał Gabrylewski*, Aleksy Patejuk** *Przedsiębiorstwo Badawczo-Wdrożeniowe Centralny Ośrodek Badawczo-Rozwojowy Aparatury Badawczej i Dydaktycznej Biuro Badań i Certyfikacji „COBRABID-BBC” sp. z o.o., ul. Łucka 13, 00-842 Warszawa **Politechnika Białostocka, Wydział Mechaniczny, ul. Wiejska 45C, 15-950 Białystok
Annals 4 No. 10, 2004 pages 212-215
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abstract In the work, the results of researches about influence sintering temperature on trybology properties of metal-matrix composite (MMC) the type of Al-Al2O3 particles, has been presented. Such a matrix material aluminium powder granulation 80÷100 μm has been used. Uncovered particles Al2O3 about size 20÷60 μm (signed as I option) and particles covered by nickel layer with thickness about 2 μm (signed as II option) made reinforced material. Samples for researching was made by hot pressing method (Tab.1) using rod about diameter φ 8 and length 10÷15 mm. Sintering time for every option was the same: 15 minutes. Made microscopic examination and analyses’ confirmed that particles without nickel layer of MMC, characterized typical adhesive connection of phases. However, in case of covered by nickel layer particles of MMC, connection between particles and matrix has diffusion - adhesive character (Fig. 1). The hardness test of composite samples by Vickers method has been done. The results showed that samples sintered with pressure 120 MPa (independently from analysed range the temperature of sintering) have the highest hardness (Fig. 2). Increasing of volume fraction of reinforced material increases hardness of samples. In next step of researching, resistance tests of abrasive wear by pin on disc method has been done. For this researching of grindability, load of 3 MPa and peripheral speed of 0.50 m/s was given. Anti-sample was made from 45 heat treatmented steel about hardness 42 HRC. The time of test was 2 hour. The controlled temperature of co-operating steam received 25 ±2oC. The results of unitary mass decrement in function of time of test has been presented in Figure 3. They are showed, that both sintering parametres and volume of fraction of reinforced material have essencial influence on level of material’s wear.The analysis of topography of co-operating surfaces and traces of wear shows, that the samples and anti-samples have the largest inequalities of surface when the sample was made with Al2O3 reinforced material without nickel layer. In these MMC samples was observed a plenty of defects (crumbling up particles) on co-operating antisamples’ surface. However, MMC samples including 10 and 20% of covered by nickel layer Al2O3 particles - the quality of cooperating surfaces was higher. First of all, so much defects and accompanying furrows situated parallel to vector of strengths of friction, was not observed. Key words: metal-matrix composite, reinforcement-Al2O3 particles