The influence of temperature of oxalic acid on the formation of well-ordered porous anodic alumina on Al-0.5 wt% Mn alloys was studied. Porous anodic alumina has been produced on Al-0.5 wt% Mn substrate by single-step anodising at 50 V in 0.5 M oxalic acid at temperature ranged from 5°C to 25°C for 60 minutes. The steady-state current density increased accordingly with the temperature of oxalic acid. Hexagonal pore arrangement was formed on porous anodic alumina that was formed in oxalic acid of 5, 10 and 15°C while disordered porous anodic alumina was formed in oxalic acid of 20 and 25°C. The temperature of oxalic acid did not affect the pore diameter and interpore distance of porous anodic alumina. Both rate of increase of thickness and oxide mass increased steadily with increasing temperature of oxalic acid, but the current efficiency decreased as the temperature of oxalic acid increased due to enhanced oxide dissolution from pore wall.
The effect of surface roughness average of hypereutectic aluminum silicon alloys (with 16 wt% Si) on the friction and wear was investigated. Various surface roughness average (Ra) of different degrees was verified as well as three different loads 10, 20 and 30 N, speeds 200, 300 and 400 rpm and relative humidity 77%. Different surface preparation techniques are resulted in different Ra values from (6, 8 and 12) ± 0.05 μm. The contacts were dried sliding and lubricated regime at 2.5 centimeters per second. Surfaces were analyzed with scanning electron microscopy and X-ray dispersive analyses. It was noted that the weighted and volumetric wear rate decreases as degree of roughness decreases, as well as coefficient of friction is considered as a function of the stability state. Wear rate is decreased and the transition stress from high to low wear is increased with increasing surface roughness average. There was a correlation between friction coefficient and hardness
This paper describes a study on the effects of heat treatment on the microstructure, hardness and wear of aluminum alloys 332 (AlSi9Cu3Mg). The solution treatment was performed at 500°C for 5 hours and then quenched in water at room temperature. Aging was performed at 170°C for 2 hours. The findings revealed that after a full heat treatment, the structure of the eutectic silicon formed toward fragmentation and spheroidization, and the silicon particles became coarse (look-like rounded). Hard intermetallic compound (Mg2Si) appeared on the microstructure after the aging treatment completed. Compared to the as-cast, the hardness of the alloys has improved to 44.84%, and the wear rate of the solution treatment had decreased to 26% while the aging treatment showed a deterioration of 79.42%. The study concludes that aging treatment improves the hardness of AA332 alloys and enhanced the wear resistance of the substance.
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