Influence of La2O3 additions on the microstructure and strength of zirconia toughened alumina

• Main Authors: Bahanurddin, N. F. K., Rosli, A. F. Z., Rejab, N. A., Abdullah, N. S., Ahmad, Z. A.
• Format: Conference Proceeding
• Language: English
• Subjects: Aluminum oxide; Bending machines; Ceramics; Data points; Flexing; Flexural strength; Grains; Lanthanum oxides; Microstructure; Modulus of rupture in bending; Transformation toughening; Zirconia toughened alumina; Zirconium dioxide
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/5.0015691

Despite the impressive recent developments in understanding transformation toughening, tailoring the strength of zirconia toughened alumina (ZTA) ceramics remains a major challenge. To address this chall enge, a simple powder mixing route involving ZTA powders with varying La2O3 additions (0 - 10 wt.%) is investigated. In this study, flexure strength measurements were determined in accordance to the ASTM B528 standard, using three point bending method on a universal testing machine (Instron, of capacity 5 kN). The measurements were carried out under a crosshead speed of 1.0 mm/min and a pre-defined support distance of 20 mm, with at least 5 specimens being used for each data point. The highest flexure strength of ZTA ceramics recorded at 75.49 MPa for 3 wt.% of La2O3 additions before decreasing to 42.95 MPa with further additions. Based on XRD analysis, a LaAl11O18 phase was detected with the addition of ≥1 wt. % of La2O3 which proved that the solubility limit was exceeded compositionally. Meanwhile, microstructural investigation of these ZTA-La2O3 ceramics revealed formations of elongated LaAl11O18 grains, clearly present between the Al2O3 and ZrO2 grains. This work provides newfound evidences for the possibility of strength-tailored ZTA ceramics, which is key for the design and fabrication of economical high-performance ceramics in years to come.