Corrosion resistance of metalized layers on steel parts in ventilation mill

Abstract

Corrosion behavior of metalized layers, obtained by Plasma Transferred Arc (PTA) process and by High-Velocity Oxygen Fuel (HVOF) process with the purpose to improve the wear resistance of vital parts of ventilation mill in a thermal power plant, has been tested. The test is performed using three electrochemical techniques, in a solution containing chloride and sulfate ions. It is shown that the steel surface (base metal) dissolves uniformly, without pitting or other forms of local dissolution. Morphology of metalized layers surface indicates that dissolution is non-uniform, but it still can be considered as general corrosion. The corrosion rate of base metal and metalized layer obtained by PTA process is rather low, while the corrosion rate of the metalized layer obtained by HVOF process is much higher. Also, the difference in corrosion potentials between the base metal and the HVOF layer is pretty high but slightly less than maximum allowed difference (prescribed by the standard), to avoid excessive galvanic corrosion. The values of corrosion rate obtained by different electrochemical techniques are in excellent agreement.

A Simple Technique for the Corrosion Inhibition of Underwater Cannonball from a Shipwreck

“…The X-ray diffraction results indicate that the sample obtained from the corroded iron contains two types of iron oxide, akageneite and lepidocrocite. The corrosion product of iron-containing chloride ions, for example, is akageneite (Jegdic et al, 2012). In addition to artifact materials, the corrosion process is influenced by environmental pollutants, other archeological materials, geography, the microorganisms in the soil, vegetation, land use, soil chemistry, soil physical properties, and the presence or absence of water and air (Mentovich et al, 2010;Cvikel and Kahanov, 2009;Selwyn, 2004).…”