Study on the Microstructure and Properties of Iron-Based Wear-Resistant Coating on the Inner Wall of an Aluminium Cylinder Block

Abstract

An arc spray gun with inner holes was used to spray two typical iron-based wear-resistant coatings, 08A and 08CrMoVA, on the inner wall of an aluminum cylinder block for an engine. In addition, microstructures of the coatings were observed through an optical microscope and a scanning electron microscope. Then, X-ray diffraction (XRD) patterns were employed to analyze the types of oxides in the coatings, and a quantitative metallographic analyzer was applied to test the porosity and the amount of oxides in the coatings. Afterwards, the coatings were immersed in the oil to conduct the wearing test and the test result showed that the coatings had better wear resistance, compared with the gray cast iron. Besides, it was further found that the coatings were formed on the substrate surface by the accumulation of flat particles, and unmelted particles, oxides, pores and fissures were also found in the coating layer. While being lubricated by oil, FeO in the coatings and the oil stored in pores decreased the friction coefficient and thus increased the wear resistance of the coating layer.