Effect of silicon addition on the oxidation mechanism of Cu-6.7percent al sintered but hot forged alloys in air

摘要

Experiments have been carried out to establish the oxidation mechanism/s of sintered but hot forged Cu-6.7percentAl alloys in air with or without the addition of silicon (0.0, 1.0 & 2.0percent) at the temperatures 523, 623 & 723 K. Analysis of the experimental data has revelated semi-logarithmic rate equation at all temperatures of oxidation for Cu-6.7;ercent Al - 2.0percent Si alloy. The rate equation conformed to the form; Wg = K_1log_(10)(K_2t+K_3) where, Wg=weight gain at time, t and K_1,K_2 & K_3 are empirically determined constants. However, the oxidation mechanism at all temperatures of oxidation for Cu-6.7percentAl and Cu-6.7percentAl-1.0percentSi followed semi-logarithmic rate equation and altered only after a certain time of oxidation even though the mechanism remained represented by the similar rate equation. The overall analysis has shown that the Cu-6.7percentAl-2.0percentSi alloy can be safely used in the air environment at an elevated temperature range between 523 and 723 K due to its highly protective,adherent and impermeable oxide layer.