Abstract
The paper presents the results of research on the tribological properties of spark-plasma-sintered Al-SiC composites. Composites with contents of 50 and 70 wt.% SiC were prepared. The sintering process was carried out using an HP D 25/3 spark plasma sintering furnace under vacuum, at the sintering temperature of 600 °C and compaction pressures of 50 and 80 MPa, respectively. The heating rate was 100 °C/min and the holding time was 10 min. Composites with a density of 91–100% were obtained. The tribological properties of the composites were evaluated based on weight loss and the coefficient of friction using a block-on-ring tribotester. Along with the weight percentage of SiC and compaction pressure, the sliding distance, and load during the tribological test were considered. Both the weight percentage of SiC and compaction pressure affected the tribological behavior of Al-SiC composites. It was found that the wear resistance was higher when a lower compaction pressure and a smaller amount of reinforcing phase (50 wt.%) were used.
Highlights
Aluminum (Al) powders are commonly used to produce composites reinforced with hard ceramic particles
The coefficient of friction determined during the run-in period under the load of 100 N and the entire test under the load of 200 N was higher. Apart from these two cases, increasing the compaction pressure applied during sintering adversely affected the coefficient of friction
The effective distance between the SiC particles was reduced owing to the higher concentration of strengthening-phase particles in the matrix, resulting from a higher applied compaction pressure, which improved the density and the hardness
Summary
Aluminum (Al) powders are commonly used to produce composites reinforced with hard ceramic particles. The basic problem that occurs when sintering Al powder is its strong affinity for oxygen, resulting in the surface of the powder particles being covered with a thin film of oxide that creates a barrier to forming a permanent intermetallic bond between the sintered powder particles. Oxygen reacts with some ceramics to form intermetallic phases affecting the quality of the metal–ceramic interface and, the final properties of the composite [1,2,3]. Al reacts with oxygen at room temperature, which results in the formation of a permanent aluminum oxide (Al2 O3 ).
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