Aluminide Coating Application for Protection of Anodic Current-Supplying Pins in Soderberg Electrolytic Сell for Aluminium Production

Anodic current-supplying pins (ACP) made of low-carbon steel corrode intensively due to the sulfur contamination of the carbon-based Soderberg anode and iron sulfides formation in the present aluminium production technology. The aluminide coatings produced by the liquid-phase method followed by the fluoride flux treatment of the steel samples were applied for the ACP protection. The protective layer based on α-Al2O3 and FeAl2O4 was formed on the steel surface in the course of the test run in the industrial Soderberg anode during the aluminium electrolysis. The aluminized ACP wear rates calculated by the linear extrapolation of data obtained during 150 days workout were 4.0 and 5.4 cm/year for the ACP with the aluminide coating and without it, respectively. The current load on the ACP remained almost the same for the aluminized and original uncoated samples with the exception of the initial “heating” period (400-600°C).