Abstract
This study shows that WC-12Co coatings with low porosity and high wear and corrosion resistance can be applied by high velocity oxygen-fuel (HVOF) on a low melting and highly flammable ZE41 magnesium alloy. This provides a novel and promising use of the high-energy thermal spraying technique on low temperature melting substrates. The spraying distance used was 300 mm, which is between two and three times the recommended distanced for HVOF coating with WC-12Co on steels. Despite this, the WC-12Co coatings obtained were homogeneous, crack-free, and dense. The coatings were very well adhered to the substrates and the spraying distance allowed avoiding any thermal affectation of the substrate. The thickness of the coatings was limited to 45 μm to avoid a big mass increase in the samples. The effect of the number of layers, the O2/H2 ratio and the gas transport flow in the coating was studied. The coatings reduced the wear rate of the substrate by 104 times, making them wear resistant. Electrochemical corrosion tests were conducted to study the corrosion protection of the coatings, showing that it is possible to protect the magnesium substrate for 96 h in contact with 3.5 wt.% NaCl aqueous solution.
Highlights
Magnesium and its alloys are increasingly being used in the automotive field because they are the lightest structural metallic materials and have excellent specific strength
The use of magnesium alloys in the transport industry is currently limited by its main drawbacks, associated with its surface properties, which are its limited resistance to corrosion and wear [3]
The feedstock WC–12Co powder had a polyhedral morphology (Figure 1a) and each powder particle consisted itself in a WC–Co cermet, this structure is characteristic of crushed particles
Summary
Magnesium and its alloys are increasingly being used in the automotive field because they are the lightest structural metallic materials and have excellent specific strength. The use of these materials could lead to a significant reduction in the weight of vehicles and, a reduction in fuel consumption. Their ability to dampen vibrations and noise, their dimensional stability, their impact resistance, and their good electrical and thermal conductivity, make them suitable for structural applications [1,2]. The expansion of the field of application of magnesium in the industries depends on the development of new technologies that minimize these disadvantages.
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