Y2O3–MgO–ZrO2 Infrared Transparent Ceramic Nanocomposites

Abstract

Increased strength and improved erosion resistance are required for future infrared windows working in harsher mechanical and thermal environments than those used today. In this study, Y2O3–MgO–ZrO2 composite nanopowders were synthesized using a sol–gel combustion process. The fully dense Y2O3–MgO–ZrO2 nanocomposites were prepared by pressureless sintering of the nanopowders at 1400°C for 2 h, followed by hot isostatic pressing at 1350°C for 1 h. The effects of ZrO2 concentration on the microstructure, infrared transmittance, and microhardness of the nanocomposites were studied. It is shown by X‐ray diffraction (XRD) and transmission electron microscopy (TEM) that ZrO2 is selectively soluble in Y2O3 with the concentration up to 13.2 mol%, forming supersaturated solid solution. The microhardness of the Y2O3–MgO–ZrO2 nanocomposites scales linearly with the square root of the ZrO2 concentration (from 10.6 GPa without ZrO2 to 13.5 GPa with 13.2 mol% ZrO2 addition). Good mid‐infrared transmittance (53%–70%) over 3–7 μm wavelength was maintained with ZrO2 concentration up to 8.8 mol%, compared with that of Y2O3–MgO nanocomposites (62%–80%) at the same wavelength range. This work shows ZrO2 solid solution strengthened Y2O3 (ZSSY) nanocomposites for their potential to be used as infrared transparent materials with enhanced mechanical properties.