J. Mater. Sci. Technol. ›› 2016, Vol. 32 ›› Issue (5): 402-410.DOI: 10.1016/j.jmst.2016.02.009

• Orginal Article • Previous Articles     Next Articles

Assessment of Elasticity, Plasticity and Resistance to Machining-induced Damage of Porous Pre-sintered Zirconia Using Nanoindentation Techniques

Abdur-Rasheed Alao, Ling Yin   

  1. Matter & Materials, College of Science, Technology & Engineering, James Cook University, Townsville, QLD 4811, Australia
  • Received:2015-08-18 Online:2016-05-10
  • Contact: Ph.D.; Tel.: +61 7 47816254; Fax: +61 747816788. (L. Yin) E-mail address: ling.yin@jcu.edu.au (L. Yin).
  • Supported by:

    The authors thank Dr. Shane Askew of the Advanced Analytical Center at James Cook University (JCU) for experimental assistance; Mr. Phillip Mcguire of Northern Petrographics Pty Ltd for sample preparation. A.R. Alao acknowledges the JCU PhD (JCU IPRS) scholarship. The work was supported by the JCU Collaboration Grants Scheme awarded to L. Yin.

Abstract:

Porous pre-sintered zirconia is subject to white machining during which its elasticity, plasticity and resistance to machining-induced damage determine its machinability and final quality. This study used nanoindentation techniques and the Sakai's series elastic and plastic deformation model to extract the resistance to plastic deformation from the plane strain modulus and the contact hardness for pre-sintered zirconia. The modulus and the resistance to plasticity were used to calculate the relative amount of elasticity and plasticity. The fracture energy and the normalized indentation absorbed energy were used to deconvolute the resistance to machining-induced cracking based on the Sakai-Nowak model. All properties were extracted at a 10 mN peak load and loading rates of 0.1-2 mN/s to determine the loading rate effects on these properties. We found that the resistance to plasticity and the resistance to machining-induced cracking were independent of the loading rate (ANOVA, p > 0.05). The elastic and plastic displacements depended on the loading rate through power laws. This loading rate-dependent deformation behaviour was explained by the maximum shear stress generated underneath the indenter and the indentation energy. The plastic deformation components and the indentation absorbed energy at all loading rates were higher than the elastic deformation components and the elastic strain energy, respectively. Finally, we established the linkage among the pore structure, indentation behaviour and machinability of pre-sintered zirconia.

Key words: Elastic/plastic deformation, Loading rate, Nanoindentation, Pre-sintered zirconia, Resistance to machining-induced cracking, Resistance to plasticity