Weibull modulus of nano-hardness and elastic modulus of hydroxyapatite coating
Here we report the microstructural dependence of nano-hardness (H) and elastic modulus (E) of microplasma sprayed (MIPS) 230 μm thick highly porous, heterogeneous hydroxyapatite (HAP) coating on SS316L. The nano-hardness and Young’s modulus data were measured on polished plan section (PS) of the coating by the nanoindentation technique with a Berkovich indenter. The characteristic values of nano-hardness and Young’s modulus were calculated through the application of Weibull statistics. Both nano-hardness and the Young’s modulus data showed an apparent indentation size effect. In addition, there was an increasing trend of Weibull moduli values for both the nano-hardness and the Young’s modulus data of the MIPS-HAP coating as the indentation load was enhanced from 10 to 1,000 mN. An attempt was made in the present work, to provide a qualitative model that can explain such behavior.
KeywordsIndentation Volume Indentation Load Weibull Modulus Indentation Size Effect Strain Gradient Plasticity
The authors are grateful to Director, Central Glass and Ceramic Research Institute (CGCRI), Kolkata for his kind permission to publish this paper and to Dr. D. K. Bhattacharya, Head, Analytical Facility Division of CGCRI for his kind encouragements during the course of this work. One of the authors (A.D.) also sincerely acknowledges the support and encouragements received from Prof. N. R. Bandyopadhyay of the School of Materials Science and Engineering, Bengal Engineering and Science University (BESU), Shibpur. The authors also appreciate the infrastructural support received from all colleagues and particularly those received from the colleagues of the Scanning Electron Microscopy Section, Mechanical Test Section, and Bio-Ceramics and Coating Division at CGCRI. Finally, the authors gratefully acknowledge financial support received from DST-SERC (Project No: GAP 0216) and CSIR (Network Project TAREMAC No: NWP 0027).
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