| In the present paper, taking 7A04 superhard aluminum alloy as matrix, selecting SiC particle as reinforcement to prepare 4 different kinds of MMCs (Metal Matrix Composites) by Agitation Casting--MMC1(7Wt%, 10μm), MMC2 (14Wt%, 10μm), MMC3 (14Wt%, 30μm), MMC4 (20Wt%, 30μm). By using the MMW-1 abrasion testing machine to study the tribological behaviors of SiCp/Al composites and 40Cr (serve as comparison) against GCr15 under the condition of non-lubrication sliding at different sliding speed (0.5m/s, 1.0 m/s, 1.5 m/s), load [5N (0.25MPa), 10N (0.51MPa), 20N (1.02MPa), 30N (1.53MPa)], and temperature (room temperature, 100℃, 150℃, 200℃, 250℃). And observe the micrographs and compositions of the worn surface, wear debris, and cross-section of SiCp/Al MMC by SEM and EDS. The relationship between MMCs' microstructure and wear performance also has been discussed.The main conclusions can be drawn through this research as following: Under the normal temperature, when sliding speed is between 0.5m/s~1.5m/s, the speed has a little influence on wear rate and friction coefficient. MMCs' friction coefficient change is no more than 0.05; the change of wear rate is no more than 1×10-8m. The load's influence is remarkable to wear rate, and a threshold value of load which is the turning point of mild wear and severe wear can be obviously observed. Moreover this threshold load comes under the MMC's characteristic influence, for example SiC particle size and weight percentage. The data proved that when the SiC particle size between 10~30μm, the bigger the particle size is, the larger the threshold load is; when the SiC particle weight percentage between 7%~20%, the larger the SiC particle weight percentage is, the bigger threshold load is. At normal temperature, the other 3 MMCs' wear-resisting property is much better compares with 40Cr, and MMC1's wear resistant performance is close to 40Cr.In the high-temperature test, temperature has dominant influence to four MMCs' wear-resisting performance. When the experimental temperature is ranging from normal temperature to 250℃, four MMCs' wear rates increase along with the temperature, such as, the wear rate of MMC1 has increased by an order of magnitude from normal temperature to 250℃. Four MMCs' friction coefficient changing tendency is similar to wear rate, increasing along with the temperature. A threshold temperature exists, which is the turning point of mild wear and severe wear and also influenced by several factors, such as, larger load (5N~30N), lower threshold temperature; higher SiC weight percentage (7%~20%), higher threshold temperature; larger SiC particle size (10μm~30μm), higher threshold temperature.Under the normal temperature, MMC abrasion mechanism may divide into three stages: (1) the first stage, slight wears, abrasion is the dominant; (2) the second stage, the Mechanical Mixed Layer (MML) is forming in this stage, primary mechanism is adhesive wear, together with oxidative wear; (3) The third stage, the Mechanical Mixed Layer (MML) is delaminating, the main wear mechanism is delamination wear. Under high temperature conditions, the wear mechanism is basic the same with normal temperature, except for each stage speeding up, and more oxidative wear, delamination wear in the wear process. At the same time, the MML is much thicker than room temperature's, which can also been proved by micro hardness (HV). It can be observed that there are 3 basic layers from the worn surface: MML, Hardened Layer, and Normal Matrix, in which MML whose thickness is dependent to load, temperature and MMC itself is a little softer than matrix; Hardened Layer whose thickness is around 40~60μm is harder than matrix by 10~15HV.
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