Erosion-corrosion behavior of SiC particle-reinforced Al-Si alloy in NaOH slurry
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cently, aluminum matrix composites (AMCs) have been used in marine and mining sectors for making components such as impellers, agitators, valves, and apex inserts for cyclone separators, etc.[1,2] Usually, these components are subjected to erosion and corrosion, and material losses occurred mainly due to the synergistic effect of mechanical wear and chemical attack. It is known that AMCs exhibited better resistance to mechanical wear than did their matrix alloys.[3] However, confusion persists regarding the corrosion behavior of AMCs, because most of the time, AMCs exhibited lower corrosion resistance than their matrix alloy.[4,5] Thus, the erosion-corrosion behavior of AMCs is expected to be a complex phenomenon. The atmospheres in mining and mineral processing industries are either acidic or basic in nature. It is reported that AMCs and their matrix alloys experienced greater corrosive attack in NaOH media than in acidic and marine media.[6] Few studies have been done to evaluate the erosion-corrosion behavior of AMCs in synthetic mine water.[7,9] These studies indicated that AMCs exhibited better performance in erosive-corrosive conditions than their matrix alloys in contrast to their performance in corrosive atmospheres such as marine and acidic environments.[8,9] The performance varied with various experimental conditions and materials-related parameters.[7,9] These studies indicated that erosion was the most dominant mode of material removal in marine and acidic environments containing suspended sand particles. Thus, it is aimed at investigating and understanding the prevailing mechanism of material removal of SiC particle–reinforced Al-Si alloy in NaOH media containing suspended sand particles.
Y.L. SARASWATHI, Senior Research Fellow, S. DAS, and D.P. MONDAL, Scientists, are with the Regional Research Laboratory (CSIR) Bhopal – 462026 (MP) India. Contact e-mail: [email protected] Manuscript submitted January 10, 2005. METALLURGICAL AND MATERIALS TRANSACTIONS A
The erosion-corrosion behavior of 10 and 15 wt pct SiC particle–reinforced Al-Si (BS: LM13) alloy in 3.5 pct NaOH solution containing 20 and 30 wt pct of suspended equiaxed silica sand particles in the size range of 250 to 300 m was investigated. The addition of 20 and 30 wt pct sand particles to the corrodant (pH 11.5) varied the pH of the slurry as 10.3 and 8.7, respectively. The erosion-corrosion tests of metallographically polished circular disc specimens were carried out using the rotating sample test method in a TR: 40 (Ducom, India) slurry abrasion tester. The samples fixed at a radial distance of 75 mm from the central impeller shaft for normal impact were rotated at a speed of 900 rpm. The details of the experimental setup is given elsewhere.[7] The wear behavior of LM13 alloy was also examined in similar experimental conditions for comparative purposes. The composition of the matrix alloy was 11.5 wt pct Si, 1.8 wt pct Ni, 1.0 wt pct Cu, 0.8 wt pct Fe, 1.0 wt pct Mg, and balance Al. The eroded-corroded surfaces were studied using a scanni
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