The Production of Transparent MgAl2O4 Ceramic Using Calcined Powder Mixtures of Mg(OH)2 and γ-Al2O3 or AlOOH



Magnesium hydroxide, Mg(OH)2 (both 99% and 99.99% purity grades), γ-Al2O3, and AlOOH have been investigated for the direct production of transparent MgAl2O4. The highest average in-line transmittance through 3.5–4 mm thick samples is 84.2 ± 1.0% at 550 nm, attained by using mixtures of 99.99% pure Mg(OH)2 and γ-Al2O3. Other formulations exhibited 77–80% visible transmission, suggesting that further optimization can improve sample consistency. All samples exhibited a Knoop hardness of ~12 GPa, and elastic modulus of ~280 GPa. Biaxial flexural strength measurements ranged from 85 to 136 MPa depending on starting materials.