Hot isostatic pressing is to be used to produce the femoral head components of hip implants made from a novel grade of zirconia. A series of manufacturing trials have demonstrated that the processing route results in post-sintered surface features 43-107 µm (mean 74 µm) in size. In clinical use it is anticipated that the femoral heads will be loaded to maximum stress level of 50% of its tensile strength once implanted. What is the critical flaw size when in service and will the implant require polishing for it to withstand loading during clinical use? Where: • You may assume a value of 1.4 for Y • The grade of zirconia has a Tensile strength of 980 MPa and a fracture toughness of 11 MPa.m0.5

Sintering of ceramics may exhibit the following characteristics: Select one or more: a. It involves the high-pressure deformation of a pre-existing shape into a new form b. The total surface area (including internal area) decreases C. Pores become smaller d. Pores become larger on average Parts of the material may become amorphous Of. The surface energy of the system increases e.

For the 21.5-cm thick multilayer assembly as listed below, please estimate the temperature on the interface between material layers 3 and 4 Material layers - counted from the interior side: (1) 1.5 - cm gypsum board; (2) 4.0-cm - concrete of density - 2400-kg/m3; (3) 10-cm of XPS foam; (4) 6.0-cm - concrete of density - 2400-kg/m3 Interior film resistance is Ri = 0.121 m2K/W Exterior film resistance is Re - 0.029 m2K/W Internal temperature +20 degC   External Temperature - 20 degC All necessary material properties can be found in the ASHRAE Handbook of Fundamentals, or other sources