摘要：The Al–Al2O3–MgO composites with added aluminum contents of approximately 0wt%, 5wt%, and 10wt%, ...The Al–Al2O3–MgO composites with added aluminum contents of approximately 0wt%, 5wt%, and 10wt%, named as M1, M2, and M3, respectively, were prepared at 1700°C for 5 h under a flowing N2 atmosphere using the reaction sintering method. After sintering, the Al–Al2O3–MgO composites were characterized and analyzed by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The results show that specimen M1 was composed of MgO and MgAl2O4. Compared with specimen M1, specimens M2 and M3 possessed MgAlON, and its production increased with increasing aluminum addition. Under an N2 atmosphere, MgO, Al2O3, and Al in the matrix of specimens M2 and M3 reacted to form MgAlON and AlN-polytypoids, which combined the particles and the matrix together and imparted the Al–Al2O3–MgO composites with a dense structure. The mechanism of MgAlON synthesis is described as follows. Under an N2 atmosphere, the partial pressure of oxygen is quite low; thus, when the Al–Al2O3–MgO composites were soaked at 580°C for an extended period, aluminum metal was transformed into AlN. With increasing temperature, Al2O3 diffused into AlN crystal lattices and formed AlN-polytypoids; however, MgO reacted with Al2O3 to form MgAl2O4. When the temperature was greater than（1640 ± 10）°C, AlN diffused into Al2O3 and formed spinel-structured AlON. In situ MgAlON was acquired through a solid-solution reaction between AlON and Mg Al2O4 at high temperatures because of their similar spinel structures.显示全部
摘要：The main objective of this paper was to fabricate Cu10Sn5Ni alloy and its composites reinforced wit...The main objective of this paper was to fabricate Cu10Sn5Ni alloy and its composites reinforced with various contents of Si3N4 particles（5wt%, 10wt%, and 15wt%） and to investigate their dry sliding wear behavior using a pin-on-disk tribometer. Microstructural examinations of the specimens revealed a uniform dispersion of Si3N4 particles in the copper matrix. Wear experiments were performed for all combinations of parameters, such as load（10, 20, and 30 N）, sliding distance（500, 1000, and 1500 m）, and sliding velocity（1, 2, and 3 m/s）, for the alloy and the composites. The results revealed that wear rate increased with increasing load and increasing sliding distance, whereas the wear rate decreased and then increased with increasing sliding velocity. The primary wear mechanism encountered at low loads was mild adhesive wear, whereas that at high loads was severe delamination wear. An oxide layer was formed at low velocities, whereas a combination of shear and plastic deformation occurred at high velocities. The mechanism at short sliding distances was ploughing action of Si3N4 particles, which act as protrusions; by contrast, at long sliding distances, direct metal–metal contact occurred. Among the investigated samples, the Cu/10wt% Si3N4 composite exhibited the best wear resistance at a load of 10 N, a velocity of 2 m/s, and a sliding distance of 500 m.显示全部
