Fracture toughness of a zirconia engineering ceramic and the effects thereon of surface processing with fibre laser radiation

Shukla, Pratik and Lawrence, Jonathan and Wu, H. (2010) Fracture toughness of a zirconia engineering ceramic and the effects thereon of surface processing with fibre laser radiation. Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 224 (10). pp. 1555-1569. ISSN 0954-4054

Full content URL: http://dx.doi.org/10.1243/09544054JEM1887

Documents
Proceedings of the Institution of Mechanical Engineers, Part B- Journal of Engineering Manufacture-2010-Shukla-1555-69.pdf
[img]
[Download]
[img]
Preview
PDF
Proceedings of the Institution of Mechanical Engineers, Part B- Journal of Engineering Manufacture-2010-Shukla-1555-69.pdf - Whole Document

1MB
Item Type:Article
Item Status:Live Archive

Abstract

Vickers hardness indentation tests were employed to investigate the near-surface changes in the hardness of a fibre laser-treated and an as-received ZrO2 engineering ceramic. Indents were created using 5, 20, and 30 kg loads to obtain the hardness. Optical microscopy, white-light interferometry, and a coordinate measuring machine were then used to observe the crack lengths and crack geometry. Palmqvist and half-penny median crack profiles were found, which dictated the selection of the group of equations used herein. Computational and analytical approaches were then adapted to determine the K1c of ZrO2. It was found that the best applicable equation was: K1c = 0.016 (E/H)1/2 (P/c3/2), which was confirmed to be 42 per cent accurate in producing K1c values within the range of 8 to 12 MPa m1/2 for ZrO2. Fibre laser surface treatment reduced the surface hardness and produced smaller crack lengths in comparison with the as-received surface. The surface crack lengths, hardness, and indentation loads were found to be important, particularly the crack length, which significantly influenced the end K1c value when K1c = 0.016 (E/H)1/2 (P/c3/2) was used. This is because, the longer the crack lengths, the lower the ceramic's resistance to indentation. This, in turn, increased the end K1c value. Also, the hardness influences the K1c, and a softer surface was produced by the fibre laser treatment; this resulted in higher resistance to crack propagation and enhanced the ceramic's K1c. Increasing the indentation load also varied the end K1c value, as higher indentation loads resulted in a bigger diamond footprint, and the ceramic exhibited longer crack lengths.

Keywords:ZrO2 engineering ceramics, Vickers indentation techniques, Fracture toughness, bmjdoi
Subjects:J Technologies > J511 Engineering Materials
J Technologies > J510 Materials Technology
Divisions:College of Science > School of Engineering
ID Code:8872
Deposited On:11 Apr 2013 16:52

Repository Staff Only: item control page