https://zirconia.typepad.com/files/zirconia-as-a-ceramic-biomaterial---piconi---biomaterials-1999.pdf

Zirconia as a ceramic biomaterial

This paper reviews the past, present, and future of the hydroxyapatite (HAp)-based biomaterials from the point of view of preparation of hard tissue replacement implants. Properties of the hard tissues are also described. The mechanical reliability of the pure HAp ceramics is low, therefore it cannot be used as artificial teeth or bones. For these reasons, various HAp-based composites have been fabricated, but only the HAp-coated titanium alloys have found wide application. Among the others, the microstructurally controlled HAp ceramics such as fibers/whiskers-reinforced HAp, fibrous HAp-reinforced polymers, or biomimetically fabricated HAp/collagen composites seem to be the most suitable ceramic materials for the future hard tissue replacement implants.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0884291400042527

Processing and properties of hydroxyapatite-based biomaterials for use as hard tissue replacement implants

Cerium dioxide (CeO2, ceria) is becoming an ubiquitous constituent in catalytic systems for a variety of applications. 2016 sees the 40th anniversary since ceria was first employed by Ford Motor Company as an oxygen storage component in car converters, to become in the years since its inception an irreplaceable component in three-way catalysts (TWCs). Apart from this well-established use, ceria is looming as a catalyst component for a wide range of catalytic applications. For some of these, such as fuel cells, CeO2-based materials have almost reached the market stage, while for some other catalytic reactions, such as reforming processes, photocatalysis, water-gas shift reaction, thermochemical water splitting, and organic reactions, ceria is emerging as a unique material, holding great promise for future market breakthroughs. While much knowledge about the fundamental characteristics of CeO2-based materials has already been acquired, new characterization techniques and powerful theoretical methods are dee...

Fundamentals and Catalytic Applications of CeO2-Based Materials

Use of CeO2-based oxides in the three-way catalysis

The recognition of the potential for enhanced fracture toughness that can be derived from controlled, stress-activated tetragonal (t) to monoclinic (m) transformation in ZrO2-based ceramics ushered in a new era in the development of the mechanical properties of engineering ceramics and provided a major impetus for broader-ranging research into the toughening mechanisms available to enhance the fracture properties of brittle-matrix materials. ZrO2-based systems have remained a major focal point for research as developments in understanding of the crystallography of the t→m transformation have led to more-complete descriptions of the origins of transformation toughening and definition of the features required of a transformation-toughening system. In parallel, there have been significant advances in the design and control of microstructure required to optimize mechanical properties in materials developed commercially. This review concentrates on the science of the t→m transformation in ZrO2 and its application in the modeling of transformation-toughening behavior, while also summarizing the microstructural control needed to use the benefits in ZrO2-toughened ceramics.

Transformation Toughening in Zirconia‐Containing Ceramics

Yttrium-doped tetragonal zirconia (Y-TZP) is expected to be a good structural ceramic material because of its high strength, high toughness and wear resistance. However, the instability (degradation) of Y-TZP around 150 to 400° C in air and above 100° C in water during ageing is a severe problem which must be solved before the direct application of this material.

Role of H2O on the degradation process of Y-TZP

Ultrafine tetragonal ZrO2 powder was prepared by hydrothermal treatment at 100 MPa of amorphous hydrous zirconia with distilled water and LiCl and KBr solutions. The resulting powder consisted of well-crystallized particles; at 200°C, the particle size was 16 nm and at 500°C, 30 nm. Under hydrothermal conditions tetragonal ZrO2 appears to crystallize topotactically on nuclei in the amorphous hydrous zirconia.

Formation of Ultrafine Tetragonal ZrO2 Powder Under Hydrothermal Conditions

This is a review and an overview on hydrothermal synthesis of fine oxide powders. The term hydrothermal today includes methods which involve water at pressures (from 1 atm-several kilobars) and high temperatures from 100–10,000°C. Hydrothermal is one of the best methods to produce pure fine oxide powders. The authors describe (i) hydrothermal decomposition, (ii) hydrothermal metal oxidation, (iii) hydrothermal reaction, (iv) hydrothermal precipitation and hydrothermal hydrolysis, (v) hydrothermal electrochemical, (vi) reactive electrode submerged arc, (vii) hydrothermal microwave, (viii) hydrothermal sonochemical, etc and also ideal and real powders

/pdf/hydrothermal-synthesis-of-fine-oxide-powders-4ph2g6lqk8.pdf

Hydrothermal synthesis of fine oxide powders

An equation for a nonlinear calibration curve of volume fraction vs integrated intensity ratio is presented for monoclinic-stabilized cubic ZrO2 systems containing YO1.5, CaO, and MgO. A parameter in the equation was evaluated theoretically and is given for a range of cubic solid solution compositions.

Quantitative Analysis of Monoclinic‐Stabilized Cubic ZrO2 Systems by X‐Ray Diffraction

Mullite (3Al2O3·2SiO2) of stoichiometric composition was prepared by mixing boehmite sol and silica dispersion and gelling at a pH of 3. Complete mullitization takes place at or above 1300°C. Ultrafine mullite powder prepared by calcining gel at 1400°C and attrition milling could be sintered to >98% (theoretical density) at 1650°C for 1.5 h. The flexural strength of the sintered body at room temperature was 405 MPa and 350 MPa at 1300°C. Only traces of a secondary phase were observed along the grain boundary.

Shigeyuki Sōmiya

Papers

Role of H2O on the degradation process of Y-TZP

Formation of Ultrafine Tetragonal ZrO2 Powder Under Hydrothermal Conditions

Hydrothermal synthesis of fine oxide powders

Quantitative Analysis of Monoclinic‐Stabilized Cubic ZrO2 Systems by X‐Ray Diffraction

Microstructure and Mechanical Properties of Mullite Prepared by the Sol‐Gel Method