Analysis on the localized corrosion of hydraulic support after short-term service in coal mine

The corrosion of hydraulic support has brought huge economic losses to coal enterprises. Using laser cladding stainless steel coating on the surface can improve its wear resistance and corrosion resistance. However, dense corrosion pits appeared on the hydraulic support coated 304 stainless steel after 25 d use in a coal mine. At present, there are few studies on the corrosion effect of this laser cladding layer under the actual mine. In this work, the oxide scales are characterized by 3D Optical Microscope (OM), Scanning Electron Microscopy (SEM) equipped with x-ray Energy Spectrometer (EDS), x-ray Photoelectron Spectrometer (XPS) and x-ray Diffraction (XRD) techniques. Based on the results, the localized corrosion mechanism is discussed. It was found that the corrosion products were mainly a mixture of (Fe,Cr)(2)O-3 and CaCO3. The maximum pitting rate calculated from the depth data of pits. which were collected by ultra-depth of field optical microscopy, was 2.32 mm a(-1). The mechanism of corrosion of hydraulic support was discussed form perspectives of the under-deposit corrosion and corrosive ions (i.e. Cl- and S-2)(-) in the environment.