Beneficial Effect of a Pre-ceramic Polymer Coating on the Protection at 900 °C of a Commercial AISI 304 Stainless Steel
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An effective and low-cost method for applying polysilazane-based barrier coating on stainless steel is presented. A SiN (PHPS) precursor has been used for applications of polymeric and ceramic-like coating material. With precursor solution in dibutyl ether, AISI 304 stainless steel substrates were coated by means of a simple dip-coating technique. After pyrolysis stage at 800 °C, the efficiency of the PHPS-based coating has been proved, and oxidation tests were done at 900 °C in air. By measuring the weight gain, and using analytical techniques as in situ X-Ray Diffraction and Scanning Electron Microscopy, it has been shown that an amorphous silica layer was formed from the initial PHPS-based coating and acts as a protective glass which provides complete separation of the AISI 304 steel surface from the oxidizing environment. This protective silica layer appears to be a very good diffusion barrier by preventing iron-containing oxide formation.