Fracture behaviour of chemical vapour deposited and hot isostatically pressed zinc sulphide ceramics
✍ Scribed by P. Ramavath; V. Mahender; U.S. Hareesh; R. Johnson; Sweety Kumari; N. Eswara Prasad
- Publisher
- Elsevier Science
- Year
- 2011
- Tongue
- English
- Weight
- 766 KB
- Volume
- 528
- Category
- Article
- ISSN
- 0921-5093
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✦ Synopsis
Fracture behaviour of zinc sulphide ceramics prepared by chemical vapour deposition (CVD) followed by hot isostatic pressing (CVD + HIP) was investigated in terms of flexural strength ( f ), plane-strain fracture toughness (K Ic ), even conditional fracture toughness (K IQ ), R-curve behaviour (variation of total fracture energy release rate, J c with crack extension, ı/ı c ) and fracture mode. The corresponding Knoop Hardness number (KHN) and its correlations to flexural strength ( f ) are also evaluated and reported. The present study showed that the zinc sulphide (ZnS) ceramics processed by CVD exhibited higher fracture resistance compared to ZnS processed by CVD + HIP condition. This observation is principally attributed to higher grain size associated with post-CVD HIPing process. In both conditions, the ZnS materials exhibited conditional fracture toughness (K IQ ) that decreased moderately with increased crack length due to the change in fracture mode form grossly tensile to predominant shear. A constantly rising R-curve behaviour was indicated in both the materials with significant increase in total fracture energy release rate (J c with the normalised displacement (ı/ı c ), a parameter representing crack extension.