Alumina-zirconia (AZ) composites are attractive structural materials, which combine the high hardness and Young's modulus of the alumina matrix with additional toughening effects, due to the zirconia dispersion. In this study, AZ composites containing different amounts of zirconia (in the range 5-20 vol %) were prepared by a wet chemical method, consisting on the surface coating of alumina powd...

The purpose of this study was to evaluate the influence of air-abrasion and subsequent heat treatment on the shear bond strength of the bond between indirect composites and a zirconia material. Four surface preparations were employed; ground flat, then heated to regenerate the crystal phase (C); air-abraded with alumina for 10 s (S10), for 20 s (S20), and air-abraded for 10 s and heated (H). Di...

The aim of this study was to investigate and compare the radio-opacity of core materials for all-ceramic restorations, such as zirconia (NANOZR and Y-TZP) and alumina, against commercially pure titanium (cpTi) and aluminum. X-ray images were taken under general settings using an X-ray film. The X-ray film images were scanned using a digital scanner, and the darkness at the central area of each ...

This paper considers the degradation of alumina and zirconia toughened alumina vs. alumina for hip implants. The materials are as assumed to be load bearing surfaces subjected to shocks in wet conditions. The load is a peak of force; 9 kN was applied over 15 ms at 2 Hz for 800,000 cycles. The volumetric wear and roughness are lower for ZTA than for alumina. The long ZTA ageing did not seem to h...

PURPOSE The purpose of this in vitro study is to examine the effects of a nano-structured alumina coating on the adhesion between resin cements and zirconia ceramics using a four-point bending test. MATERIALS AND METHODS 100 pairs of zirconium bar specimens were prepared with dimensions of 25 mm × 2 mm × 5 mm and cementation surfaces of 5 mm × 2 mm. The samples were divided into 5 groups of 2...

Weakly bonded particle mixtures of mullite and alumina are assessed as candidate matrixes for use in porous matrix ceramic composites. Conditions for the deflection of a matrix crack at a fiber-matrix interface are used to identify the combinations of modulus and toughness of the fibers and the matrix for which damage-tolerant behavior is expected to occur in the composite. Accordingly, the pre...

OBJECTIVES To evaluate the bonding of resin-cement to yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) via silica coating followed by silanization, and three one-bottle universal adhesives, with or without prior conditioning using a zirconia primer. METHODS Y-TZP specimens (n=160) were conditioned by tribochemical silica coating and silanization (CS), or alumina sandblasting with one...

Large whiskers of a new KAl9O14 polymorph with mullite-type structure were synthesized. The chemical composition of the crystals was confirmed by energy-dispersive X-ray spectroscopy, and the structure was determined using single-crystal X-ray diffraction. Nanosized twin domains and one-dimensional diffuse scattering were observed utilizing transmission electron microscopy. The compound crystal...