A method of microarc oxidation (MO) on aluminium-silicon alloys has been developed to provide a wear-resistant coating for the internal surfaces of an automotive cylinder block cast from aluminium-silicon alloys. The results obtained in this study demonstrate the effect on MO coat quality by a pre-processing heat treatment prior to MO. The treatment is carried out to change the shape and size of the eutectic and/or primary silicon particles to form the required microstructure. This MO method can be applied to improve the wear-resistance of aluminium-silicon alloys provided the necessity of maintaining low wear on the counterbodies contacting with coat is taken into account. Silicon particles have been found to inhibit the oxide layer propagation in aluminium-silicon alloys that had undergone the microarc oxidation process. The basic factors influencing the oxidation of aluminium-silicon alloys have been determined to be the size, shape and distribution of the silicon particles. The properties of MO coatings can be optimised by the creation of specific microstructures of oxidized alloys through the use of specific heat treatments prior MO process. The Mo process has been observed to fill near-surface pores in cast aluminium alloys ('Pore healing'). The MO technology was tested in an experimental engine block using AK6M2 aluminium-silicon alloy and positive results were obtained. This ensures that the wear-resistance for the aluminium block, piston rings and pistons is at a level not less than that in a cast-iron block. This ensures that the materials for pistons and piston rings need not be changed.
A wear-resistant coating for aluminium-silicon alloys using microarc oxidation and an application to an aluminium cylinder block
Eine verschleißfeste Beschichtung für Aluminium-Silicium-Legierungen auf der Grundlage einer Mikrolichtbogenoxidation und eine Anwendung für ein Aluminium-Zylinderkurbelgehäuse
2002
10 Seiten, 18 Bilder, 3 Tabellen
Aufsatz (Konferenz)
Englisch
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