Abstract No.:
2973

 Scheduled at:
Tuesday, September 27, 2011, Saal B2.2 2:25 PM
Tribological Coatings 1


 Title:
Understanding the intrinsic correlation between thermo-mechanical properties and microstructural characteristics of plasma sprayed coatings

 Authors:
Zhi-Jian Yin* / Institute of Surface Technology, Baosteel Equipment Maintenance Co., Ltd., China
XinHai Tan / Institute of Science Technology, Baosteel Equipment Maintenance Co., Ltd.,, China
ShunYan Tao/ The Key Laboratory of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Science, China
ChaoXiong Li/ Institute of Science Technology, Baosteel Equipment Maintenance Co., Ltd.,, China
QingXin Wang/ Institute of Science Technology, Baosteel Equipment Maintenance Co., Ltd.,, China
ChuanXian Ding/ The Key Laboratory of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Science, China

 Abstract:
Though it is generally accepted and a number of related investigations published that microstructure of thermal-sprayed coatings exhibits anisotropic behavior and embodies some defects such as weak interface between splats, irregular reticula of inter/intra-cracks and pores for the successively immediate solidification of the liquid or partially melted droplets onto target substrate during spraying process, in turn affecting its thermo-mechanical properties, more attentions need to be payed. Based on our previous researches (J. Therm. Spray Technol., 18 (2009) 292-296; J. Eur. Ceram. Soc. 28(2008)1143-1148; J. Phy. D. 40 (2007) 7090-7096; Mater. Sci. Eng. A, 394(2005) 229-237; Surf. Coat. Technol., 135(2001) 229-237.) and some up-to-date experimental results, the present study aims to comprehensively elaborate the intrinsic correlation between thermo-mechanical properties including thermal diffusivity, thermal expansion coefficient, microhardness, fracture toughness, elastic modulus and bending strength and microstructural characteristics, in addition to residual stress distribution and testing conditions. Al2O3 and Cr3C2-NiCr coatings, as examples of typical thermal sprayed ceramic deposits, were plasma sprayed from powders with different size distribution and manufacturing process, and their microstructural characteristics including phase composition and size, splat and inter/intra-cracks morphology, pore size and morphology and porosities were evaluated. Indention method, three-point bending and laser-flash techniques were employed to measure above mentioned thermo-mechanical properties under different conditions. In order to well estimate the reliability and variability of measured data sets, statistical approach like Weibull distribution and line regression were used. Correlations between microstructural characteristics and evaluated thermo-mechanical properties were discussed.
Results show that thermal-mechanical properties of coatings is closely correlated to some microstructural characteristics like splat nature (size, morphology and interface density), pore nature (size, morphology and density) and testing conditions, besides of residual stress distribution, porosity and anisotropic behaviours of coating, which is determined by flame-particle and particle-particle interactions through deposition.


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