Microstructural influence on erosion behaviour of thermal spray coatings

Journal Article · Mon Jan 15 04:00:00 EST 2007 · Materials Characterization

DOI:https://doi.org/10.1016/j.matchar.2006.03.014· OSTI ID:21003522

Matthews, S J ^[1]; James, B J ^[1]; Hyland, M M ^[1]

---

1. Department of Chemical and Materials Engineering, University of Auckland, Private Bag 92019, Auckland (New Zealand)

The influence of structure on erosion performance of thermally sprayed Cr{sub 3}C{sub 2}-NiCr coatings under industrial turbine conditions has been investigated. Thermal spraying of these materials results in substantial variation in composition and microstructure due to exposure of the coating powders to the high temperature accelerating gas. Coatings were characterised using Back Scatter Electron imaging in conjunction with X-ray diffraction which showed carbide dissolution into the matrix of varying extent depending on deposition technique. Heat treatment at 900 deg. C caused carbide precipitation and matrix refinement. Erosion testing of as-sprayed and heat treated coatings was conducted at ambient and elevated temperature. Single impacts were characterised using Scanning Electron Microscopy in order to determine the erosion mechanism. At ambient temperature the single impacts caused a brittle response with both carbide grains and matrix being cleaved by the erodent particle. Brittle cracks surrounded each impact and intersected with splat boundaries leading to a significant contribution to erosion rate from splat structure. Following heat treatment the erosion response of the coatings was more ductile with mounds of plastically deformed material surrounding each impact, this significantly reduced erosion rate.

• OSTI ID: 21003522
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Journal Issue: 1 Vol. 58; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHROMIUM CARBIDES
CRACKS
DISSOLUTION
EROSION
FUELS
HEAT TREATMENTS
MICROSTRUCTURE
PERFORMANCE
PRECIPITATION
SCANNING ELECTRON MICROSCOPY
SPRAY COATING
SPRAYED COATINGS
TURBINES
X-RAY DIFFRACTION