Structural properties of new siliconized coatings formed by pyrolytic decomposition of pure TPOS

New anticorrosion siliconized coatings are formed by pyrolytic decomposition of sprayed pure tetraphenoxy silane TPOS.on surfaces of carbon steel specimens, in a preheated furnace within a temperature range 500–6508C. The optimum conditions for developing highly corrosion resistant siliconized coatings, are decided by the aids of structural and composition analysis techniques. By the aid of EDXRF, SEM, Ultra Sonic Cleaner USV., cross-edged SEM micrographs, O.M. and T hin Film On Surface TFOS.software program, the optimal thickness, structure free voids interface and maximum adhesion properties of the produced siliconized coatings, were determined at 6008C for pyrolytical time 45 min. Evaluation of the coatings’ composition yielding a high anticorrosion property is fully detailed by the aid of XRD analysis, electrochemical dissolution in different acidic media and adhesion techniques. The microstructure of the optimum siliconized coatings is regular in shape, size, orientation and boundaries of the formed bulky aggregated particles. Also the striations around the coatings’ particles are mostly narrow. The strong adhesion property of the coatingrmetal surface interface, is assessed on the basis of the ‘go, no go’ principle and is related to the inner diffusion of silica rooting phenomenon.. The variation in the constituents’ ratios of the produced coatings at different temperatures is attributed to the rate of interconversion of the microcrystallite SiO2 to crystalline phases and rate of interaction between the diffused iron, Fe2q, and the crystalline phases of SiO2. Electrochemical dissolution performance for uncoated and coated electrodes in the range of 0.1–10 M HCl solutions reveal that no significant corrosion behavior is observed. However, the variation between anodic and cathodic routes, is referred to the formation of strong passive irreversible phases on the electrode’s surface. These phases could initiate from metal ions Fe2q.either provided by the metal surface in case of uncoated electrodes. or by the siliconized coatings’ enriched iron constituents in case of coated electrodes.. q1999 Elsevier Science B.V. All rights reserved.