Enhancing Flexural Strength of 96-Alumina Ceramics to Improve Anti-Burst Capability in Capacitive Pressure Sensors

Abstract

The sensing diaphragm made of 96 wt% alumina (96-alumina) ceramics is one of the key components of capacitive pressure sensors used in harsh environments.Nevertheless, their anti-burst capability is severely limited by the poor flexural strength of 96-alumina. Herein, we employed the combined Ce 4+ -doped ZrO 2 reinforcement phase and Kyanite coating to improve the flexural strength of 96-alumina ceramics. Ce 4+ was doped into ZrO 2 to generate second phases of (Zr 0.9 Ce 0.1 )O 2 , which significantly 2 stabilized the t-ZrO 2 phase at room temperature. Attributed to phase transformation strengthening effect, the flexural strength of the composite was enhanced from 296.72 MPa to 326.26 MPa. By further coating the (Zr 0.9 Ce 0.1 )O 2 -reinforced 96-alumina with a Kyanite layer of 20-30 μm thick, needle-like or rod-like mullite phases were formed to induce crack deflection. Therefore, the flexural strength was significantly improved to 473.22 MPa, which is the highest reported flexural strength for 96-alumina so far. The anti-burst pressure was increased from 4.4 MPa to 5.6 MPa without sacrificing the sensitivity of capacitive pressure sensors. This study proposes a feasible method to increase the flexural strength of 96-alumina ceramics, enhancing burst resistance in ceramic-based capacitive pressure sensors.