Газотворность покрытий для литья дисков автомобильных колес в металлической форме автомобильных колес в металлической форме под низким давлением=Gas production ability of coatings used in low-pressure casting of car wheels

Abstract

Light-alloy wheels have a complex cross-sectional profile. It means that they can have hot points which may potentialy produce gas porosity. One of the factors that may cause gas porosity includes the gas production ability of parting coatings. This paper presents a comparative analysis of how the gas production ability of parting coatings may impact the quality of wheels produced by low-pressure casting. The gas production ability of the coatings in view was analysed by measuring the density of gases that occur at the temperature when the melt gets in contact with the coated mold. The analysis was performed in the TA Instruments SDT Q600 thermoanalyser integrated with a Fourier infrared spectrometer. The study helped understand the kinetics of gases produced by heat-coductive and heat-sealing coatings under rising temperature. The measured optical density indicate that, at the contact temperature, the layer of the KTP110 heat-conductive coating, which was developed by the Department of Casting of the Siberian Federal University, produces less gases than ist foreign counterpart – D1. A double decrease in the amount of produced gases is associated with a 20 % reduction in gas defects in low-pressure cast wheels. Under the same temperature conditions, i.e. 690–720 oC, the developed heat-sealing coating Zh160 shows a 25% lower gas production ability compared with the D2 coating. Further compositional modification would impy further reduction in gas production with no impact on the heat-sealing properties. Consequently, the use of parting coatings with a low gas production ability provides one of the effective and feasible solutions that can help eliminate gas defects in low-pressure castings © 2019, “Ore and Metals” Publishing house. All rights reserved