Corrosion properties of stainless steel coatings made by different methods of thermal spraying

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:160436

Siitonen, P; Konos, T; Kettunen, P O ^[1]

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1. Tampere Univ. of Technology (Finland)

The corrosion protection ability of thermally sprayed stainless steel coatings in aggressive environments is considerably limited as compared to bulk materials of the same composition. The two main reasons for the decrease in corrosion resistance are the porosity in the coatings and the oxidation of elements, particularly chromium, during spraying process. The corrosion resistance and structure of stainless steel coatings, ANVAL 254 SMO, made by different methods of thermal spraying were evaluated in this work. The coatings were produced by atmospheric plasma spraying (APS), atmospheric plasma spraying using gas shielding around the plasma (APS/S), low pressure plasma spraying (LPPS), detonation gun spraying (DGS) and high velocity oxyfuel spraying (HVOF). Electrochemical methods were used for determining the corrosion protection ability of coatings in 3.5% NaCl-solution and in sulfur acid solution (pH 3 and 1). The structure and composition of coatings were studied by optical microscopy and scanning electron microscopy/energy dispersive analysator (SEM/EDS). The porosity of the coatings was determined by water impregnation method, optical microscopy and mercury porosimeter. The results showed that the best coating quality can be achieved by LPPS- and HVOF-coatings. Oxidation and porosity restrict the use of APS-coatings in corrosive environments. The oxidation can be avoided by using argon gas shield around the plasma flame during spraying. Due to porosity all studied coatings suffered crevice corrosion in chloride solution. Despite high Mo-alloying the best coatings reached only the corrosion resistance of AISI 316.

• OSTI ID: 160436
• Report Number(s): CONF-940684--; ISBN 0-87170-509-5
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHROMIUM ALLOYS
COPPER ADDITIONS
CORROSION RESISTANCE
CURRENT DENSITY
ELECTROCHEMICAL CELLS
FLAME SPRAYING
IRON BASE ALLOYS
MICROSTRUCTURE
MOLYBDENUM ALLOYS
NICKEL ALLOYS
NITROGEN ADDITIONS
OPTICAL MICROSCOPY
OXIDATION
PLASMA ARC SPRAYING
POROSIMETERS
POROSITY
SCANNING ELECTRON MICROSCOPY
SPRAY COATING