Date of Award
Master of Science (MS)
A recently discovered sintering mechanism called flash sintering where densification of a green ceramic compact happens in seconds rather than hours is the interest of this work. A rather interesting result is found at the end of this work about the effect of flash on the elastic modulus of 3mol% Yttria-Partially stabilized zirconia (3Y-TZP) during flash. To interpret the relation between
natural frequency and elastic modulus of a cantilever beam,Euler-Bernoulli beam theory coupled with a spring mass damper system was used. Fast Fourier Transform and Finite Element Analysis were employed to analyze the material vibrations and measure the change in natural frequency and elastic modulus of softened region. Initial experiments were performed in a furnace to get a baseline plot of elastic modulus vs temperature (up to 1200℃), which is an inverted ’S’ shape curve stabilizing at higher temperatures. Also, measurements were conducted while maintaining flash for four current densities: 60, 80, 100, and 120 mA mm-2 covering a range of flash lengths (10, 20, and 30mm) and furnace off state. Damping coeffcient was also calculated simultaneously to obtain the undamped natural frequency. This work confirms the supposition that there is softening of elastic modulus with the effect becoming more prominent with increasing current densities when in the state of flash. A drop of 30% in elastic modulus has been observed during flash with respect to the modulus at that temperature (without flash).
Kathiria, Rushi Keshav, "In-Situ Measurements of the Elastic Modulus of Zirconia Polycrystals Held in a State of Flash Induced by an Electric Field" (2018). Mechanical Engineering Graduate Theses & Dissertations. 188.