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Title: Microstructural influence on erosion behaviour of thermal spray coatings

Abstract

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.

Authors:
 [1];  [2];  [1]
  1. Department of Chemical and Materials Engineering, University of Auckland, Private Bag 92019, Auckland (New Zealand)
  2. Department of Chemical and Materials Engineering, University of Auckland, Private Bag 92019, Auckland (New Zealand). E-mail: b.james@auckland.ac.nz
Publication Date:
OSTI Identifier:
21003522
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 58; Journal Issue: 1; Other Information: DOI: 10.1016/j.matchar.2006.03.014; PII: S1044-5803(06)00098-2; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
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

Citation Formats

Matthews, S.J., James, B.J., and Hyland, M.M. Microstructural influence on erosion behaviour of thermal spray coatings. United States: N. p., 2007. Web. doi:10.1016/j.matchar.2006.03.014.
Matthews, S.J., James, B.J., & Hyland, M.M. Microstructural influence on erosion behaviour of thermal spray coatings. United States. doi:10.1016/j.matchar.2006.03.014.
Matthews, S.J., James, B.J., and Hyland, M.M. Mon . "Microstructural influence on erosion behaviour of thermal spray coatings". United States. doi:10.1016/j.matchar.2006.03.014.
@article{osti_21003522,
title = {Microstructural influence on erosion behaviour of thermal spray coatings},
author = {Matthews, S.J. and James, B.J. and Hyland, M.M.},
abstractNote = {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.},
doi = {10.1016/j.matchar.2006.03.014},
journal = {Materials Characterization},
number = 1,
volume = 58,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}