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Electro-spark deposition (ESD) or low energy welding (LEW) technique allows the coating of metallic materials with different metal and alloys, conductive ceramics and conductive ceramic metal composites. It is also known as micro-joining process to improve the wear properties of the substrate or to obtain a more durable upper superficial coating. In this study, the surfaces of AISI 1040, AISI 4140 and AISI 5140 steels were coated with WC electrode at constant rotational speed and then characterized by a metallographic study. A homogeneous coating thickness was observed in microscopy studies and the formation of W2C phase in the coating layer was determined in XRD analysis. Hardness of WC coated samples increased approximately 5 times. Abrasion tests were carried out by ball-on disc method with WC–Co ball at 250 m under 5N load. In the abrasion tests with WC–Co ball, the best abrasion resistance is obtained with WC coated AISI 5140 steel, while the lowest strength is obtained with uncoated AISI 4140 steel. [ABSTRACT FROM AUTHOR]

AISI 316 L austenitic stainless steel is widely used in various sectors of the industry (chemical, petro-chemical industry, paper industry, nuclear engineering, dairy equipment and medical field) because of its good corrosion resistance and biocompatibility. In contrast to these superior properties, it has a low hardness and poor wear performance, thus, limiting its use in some areas of industry. As a result of progress in science and technology, the expectation of superior properties from materials has increased and the surface modification has become an important part of this development. Amongst many coating processes, Electro-spark Deposition (ESD) is a micro-bonding process that is used to deposit a stronger, more robust and durable coating layer on a metallic substrate. This method can also be used to repair damaged parts, tools or equipment or to extend the tool and equipment life. In this study, the surface of AISI 316 L stainless steel was coated with WC and Ti6Al4V by ESD method. Morphology and microstructure of the deposited layers were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Surface hardness distributions were determined with a micro hardness tester. XRD analysis revealed that Fe–α, Fe–γ, W2C, Cr–Ti, Al–Fe–Ti phases exist on the deposited layers. The wear behavior of the coated surfaces was carried out by ball-on-disc wear method using WC-Co ball bearing with a diameter of 8 mm for a sliding distance of 250 meters at a sliding rate of 0.3 m/s under a dry condition using a load of 5 N. Corrosion behavior of coated surfaces i.e. Tafel extrapolation and linear polarization methods were investigated for the duration of 1 h in the SBF (Simule Body Fluid) solution. Morphology of layers formed on steel surface was examined by SEM microscope. Wear tests showed that AISI 316 L stainless steel has a low surface hardness but wear resistant coatings improved this property. The wear rate of coated AISI 316 L stainless steel decreased by 3–10 times with respect to the type of coating. The electrochemical experiments showed that the expected improvement was not achieved due to the high corrosion resistance of AISI 316 L stainless steel. However, the weakness of the surface hardness was partly replaced by an acceptable compromise from corrosion resistance. [ABSTRACT FROM AUTHOR]