| The fracture toughness of advanced ceramics is often measured using an indentation technique. A polished surface of the material under test is indented using a Vickers hardness tester, the cracks which emanate from the corners or the indents are then measured and provide an indication of the toughness of the material. Typical microstructures of weak (Fig 1. KIC ~ 3 MPa.m˝) and a tough (Fig 2. KIC ~ 12 MPa.m˝) Technox® zirconia are detailed below: 
Figure 1. Microstructure of a low fracture toughness advanced ceramic. 
Figure 2. Microstructure of a high fracture toughness advanced ceramic. 
Figure 3. These values are typical of those obtained from test pieces and are offered for guidance in the design of engineering components. | 
Dynamic-Ceramic -Transformation Toughened Ceramics
