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Corrosion properties of thermally sprayed bond coatings under plasma sprayed chromia coating in sulfuric acid solutions

Tutkimustuotosvertaisarvioitu

Yksityiskohdat

AlkuperäiskieliEnglanti
OtsikkoInternational Thermal Spray Conference and Exposition, ITSC 2019
AlaotsikkoNew Waves of Thermal Spray Technology for Sustainable Growth
ToimittajatF. Azarmi, Y. Lau, J. Veilleux, C. Widener, F. Toma, H. Koivuluoto, K. Balani, H. Li, K. Shinoda
KustantajaASM International
Sivut923-930
Sivumäärä8
ISBN (elektroninen)9781510888005
TilaJulkaistu - toukokuuta 2019
OKM-julkaisutyyppiA4 Artikkeli konferenssijulkaisussa
TapahtumaINTERNATIONAL THERMAL SPRAY CONFERENCE -
Kesto: 1 tammikuuta 1900 → …

Julkaisusarja

NimiProceedings of the International Thermal Spray Conference

Conference

ConferenceINTERNATIONAL THERMAL SPRAY CONFERENCE
Ajanjakso1/01/00 → …

Tiivistelmä

Plasma sprayed chromia coatings are known to have excellent corrosion and wear properties in highly acidic conditions at ambient and elevated temperatures. In applications requiring extremely good corrosion resistance, the whole components are usually made of a corrosion resistant alloy. For increased adhesion of the ceramic coating to the corrosion resistant substrate material, thermally sprayed metallic bond coatings are used. It is well known that the corrosion environment in such bond coatings between the ceramic top coating and the substrate can be extremely difficult due to the absence of dissolved oxygen, increased concentration of the corrosive electrolytes under the top coating, and galvanic and crevice corrosion mechanisms inside the coating structure. When bond coatings are used, it is of high importance to select the bond layer chemistry and method of production so that the bond coating can survive in such harsh conditions. In the present study, four different bond coatings were studied to evaluate their performance in corrosive acidic electrolytes. The coatings studied were HVOF sprayed Ni-20Cr, Hastelloy C-276 and Ultimet alloy coatings, and plasma sprayed tantalum coating. The substrate material was a solid Hastelloy C-276 metal alloy. The top coating used was plasma sprayed Cr2O3. Corrosion properties of various coating types were studied by electrochemical measurements in sulfuric acid solutions with various concentrations at RT, and by immersion tests at RT and at the temperature of 60°C. The coating microstructures were studied before and after the corrosion tests. The results showed that HVOF sprayed Ni-20Cr and Ultimet alloy coatings were significantly attacked by the sulfuric acid electrolyte, whereas HVOF sprayed Hastelloy C-276 and plasma sprayed Ta coatings performed significantly better.

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