New types of protective coatings and development of test methods

Abstract

The paper presents the results of synthesis and characterisation of refractory coatings based on various fillers intended for the protection of metallic structures. Refractory fillers applied are based on mullite, cordierite, zirconium silicate, and pyrophyllite. Refractory filler samples are treated by micronization grinding down to 15 m filler particles. Methods as XRD, SEM, and optical microscopy are used for characterisation. Performed tests determined the optimal composition of protective coatings and manufacturing processes. According to standard ASTM G32 an ultrasonic vibrational method with stationary sample was used for characterising the obtained coatings. The goal of the research was to determine the coating quality and its applications in metallic surface protection in conditions of wear, corrosion, cavitation, and high temperature. All coatings were tested under the same conditions. A comparison of cavitation resistance is given for tested coatings. Coating quality is evaluated based on cavitation loss rate and on the analysis of sample surface damage formation and development under effects of cavitation.

U radu su prikazani rezultati sinteze i karakterizacije vatrostalnih premaza na bazi različitih punioca namenjenih za zaštitu metalnih konstrukcija. Korišćeni su vatrostalni punioci na bazi mulita, kordijerita, cirkonijum silikata i pirofilita. Uzorci vatrostalnih punioca podvrgnuti su mikronizirajućem mlevenju na veličinu zrna punioca 15 m. Za karakterizaciju dobijenih punioca korišćene su metode XRD, SEM i optička mikroskopija. Ispitivanjem je određen optimalni sastav zaštitnih premaza i postupci njihove izrade. Za karakterizaciju dobijenih premaza primenjena je ultrazvučna vibraciona metoda sa stacionarnim uzorkom prema standardu ASTM G32. Cilj ispitivanja bio je određivanje kvaliteta premaza i mogućnosti primene za zaštitu metalnih površina u uslovima habanja, korozije, kavitacije i povišenih temperatura. Svi premazi su ispitivani pod istim uslovima. Prikazan je uporedni pregled kavitacione otpornosti ispitivanih premaza. Kvalitet premaza ocenjen je na osnovu vrednosti kavitacione brzine, analize nastajanja i razvoja oštećenja površine uzoraka pod dejstvom kavitacije.