Microstructural and corrosion resistance aspects of Fe-Cr and Fe-Co alloys thermically sprayed by electric arc

Materia

article

Erika dos Santos Pereira¹  Hector Reynaldo Meneses Costa¹  André Rocha Pimenta²  Marilia Garcia Diniz³ 

[1] Centro Federal de Educação Tecnológica Celso Suckow da Fonseca;Instituto Federal do Rio de Janeiro;Universidade do Estado do Rio de Janeiro

关键词: Thermal spraying;    Metal coatings;    Digital image processing;    Corrosion test;   

DOI  :  10.1590/S1517-707620210004.1376

学科分类：工程和技术（综合）

来源: Universidade Federal do Rio de Janeiro * Coordenacao dos Programas de Pos-Graduacao de Engenharia

【 摘 要 】

The aim of this work was to quantify and evaluate, through techniques of analysis and digital image processing (PDI), defects formed in metallic coatings based on ferro-nickel, iron-chromium and cobalt-chromium alloys obtained by thermal arc-electric spraying. Images obtained by optical microscopy (OM) were processed and analyzed using the FIJI software (Image J) for quantification of pores, oxide networks and cracks. Measurements of Vickers microhardness (HV) and corrosion tests according to the ASTM-G48. Two corrosion tests were carried out in ferric chloride medium: one exposing only the coating, where the corrosion resistance was evaluated qualitatively through OM images and the possible presence of corrosion pits and the other exposing the coating and substrate set, in this case, the corrosion resistance was quantitatively evaluated through measurements on the thickness of the coating layer before and after exposure. An assessment of the microstructural morphology by optical microscope (OM) and scanning electron microscope (SEM) was made. The results obtained by OM and SEM indicated that the coatings showed uniformity throughout the deposited layer and low number of defects (oxides, cracks and porosities). The percentage of defects found varied between 3.7% and 4.3% for the coatings studied. All showed excellent resistance to corrosion in ferric chloride, which is considered aggressive to stainless steels, except for the cobalt-based coating alloy when it was combined with copper and with the substrate also exposed to the corrosive environment.

【 授权许可】

CC BY