Chlorine induced high-temperature corrosion mechanisms in HVOF and HVAF sprayed Cr3C2-based hardmetal coatings. (November 2019)

• Record Type: Journal Article
• Authors: Fantozzi, Davide; Matikainen, Ville; Uusitalo, Mikko; Koivuluoto, Heli; Vuoristo, Petri
• Is Part Of: Corrosion science. Volume 160(2019)
• Publication Date: 2019-11
• Subjects: A. Metal matrix composites -- A. Superalloys -- B. SEM -- B. TGA -- B. XRD -- C. Chlorination -- C. High temperature corrosion -- C. Thermodynamic diagrams; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2019.108166
• Languages: English
• ISSNs: 0010-938X

Abstract

Highlights: High temperature corrosion properties of HVOF and HVAF Cr3 C2 -based coatings. Synergistic use of TGA and furnace corrosion tests. A corrosion mechanism for chloritizing-oxidizing condition was proposed. Temperature ranges were identified for the onset of chlorine corrosion. Fine secondary carbide precipitates were highly detrimental in the test conditions. Abstract: A novel method that combines thermal analysis and traditional furnace corrosion tests was used to study the corrosion behaviour of thermally sprayed Cr3 C2 -based hardmetal coatings at 450 °C and 550 °C under a KCl deposit. This method enabled the identification of the onset temperature of chlorine-induced oxidation to be within 450–500 °C. Two corrosion mechanisms were suggested for these temperatures. At 450 °C, the corrosion rate was slow and mainly controlled by the formation of K2 CrO4 . Exposure at 550 °C caused the formation of fine interconnected secondary-carbide precipitates in the metal matrix. Their fast corrosion was identified as the major cause of degradation.