Processing and Properties of Zirconia-Toughened Alumina Prepared by Gelcasting

Abstract

Zirconia-toughened alumina (ZTA) using yttria-stabilised zirconia is a good option for ceramic-ceramic bearing couples for hip joint replacement. Gelcasting is a colloidal processing technique capable of producing complex products with a range of dimensions and materials by a relatively low-cost production process. Using gelcasting, ZTA samples were prepared, optimising the stages of fabrication, including slurry preparation with varying solid loadings, moulding and de-moulding, drying and sintering. Density, hardness, fracture toughness, flexural strength and grain size were observed relative to slurry solid loadings between 58 and 62 vol. %, as well as sintering temperatures of 1550 °C and 1650 °C. Optimal conditions found were plastic mould, 4000 g/mol PEG with 30 vol. % concentration, 61% solid loading and Ts = 1550 °C. ZTA samples of high density (maximum 99.1%), high hardness (maximum 1902 HV), high fracture toughness (maximum 5.43 MPa m1/2) and high flexural strength (maximum 618 MPa) were successfully prepared by gelcasting and pressureless sintering.

Refitting of Zirconia Toughening into Open-Cellular Alumina Foams by Infiltration with Zirconyl Nitrate

“…Finally, the strength data obtained for the different sample series with alumina–zirconia infiltration were successfully modeled using equation 3 with n = 2.25, C 6 = 0.65, and a bending strength of the strut material σ fs converged to 575 MPa (Figure 11, left). The obtained bending strength is in good accord to literature data for bulk ZTA ceramics made by shaping and sintering at ambient pressure [63,64]. This represents the expected toughening effect of the strut material due to the zirconia loading.…”

Hardness and modulus of elasticity of atomic layer deposited Al2O3-ZrO2 nanolaminates and mixtures

“…Usually zirconia is processed at high temperatures (over 1000 � C), but ALD can be conducted at relatively low temperatures. ZrO 2 can be grown at temperature as low as about 200 � C from ZrCl 4 and water process [1,2,19]. The content of unwanted impurities (i. e. chlorine ions) might have increased levels at low deposition temperatures due to the incomplete surface reactions.…”

Effect of MgO Addition on the Mechanical and Dynamic Properties of Zirconia Toughened Alumina (ZTA) Ceramics

“…The ZTA mixture was added with different amounts of MgO (0–0.9 wt.%). The details of preparation procedures can be found elsewhere [34,35,36]. Two different sizes of ZTA pellets were prepared.…”

“…The enhancement of fracture toughness and hardness of ZTA ceramics has received a great amount of interest from many researchers [34,35,36,37]. Thus, appreciable attempts have been made to address effective approaches to improve ZTA ceramics’ mechanical properties through dispersing suitable second phase reinforcements such as whiskers, fibers, ductile particles or platelets within the continuous ZTA matrix.…”