Apatite-polymer composites mimicking specific structure of natural bone are promised as bone substitutes with moderate flexibility able to be fabricated into desired shapes as well as bone-bonding bioactivity. In order to precipitate the apatite on polymer surfaces, aqueous processing using solution supersaturated to the apatite has been attracting as much attention. Polyglutamic acid (PGA) is ...

S U M M A R Y . The high-temperature transformation of andalusite (AI2SiOs) into 3/2-mullite (3AIzO32SiO2) plus vitreous silica (SiO2) has been studied within the temperature interval from 13oo to 16oo ~ by means of X-ray powder and single-crystal techniques and by infrared spectroscopy. Results are interpreted in terms of a topotactic transformation in which (oi I) and (oI i) planes of andalus...

Mullite and mullite/ZrO2-7wt.%Y2O3 coatings could be thought among the main protective layers for environment barrier coatings (EBCs) to protect Si-based substrates in future gas turbine engines. Considering that feedstock of the compound powder is not commercially available, two powder processing routes Spray Drying (SD) and Flame Spheroidization (FS) were implemented for both types of powders...

A strategy is proposed to reduce surface tensile stresses that develop in ceramic microlaminate structures. As a specific example, surface stresses, which can lead to unwanted edge cracking, appear within a thin alumina/mullite layer bounded by thicker alumina layers after fabrication at some elevated temperature and subsequent cooling. A stress analysis is performed using the finite element me...

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...

Aim: Calcium silicate cements are widely used in endodontics. Novel fast-setting calcium silicate cement with fluoride (Protooth) has been developed for potential applications in teeth crowns including cavity lining and cementation. Objective: To evaluate the surface apatite-forming ability of Protooth compositions as a function of fluoride content and immersion time in phosphate-buffered salin...

The ability of bile salts to inhibit the precipitation of either calcium hydroxyapatite or its precursor, amorphous calcium phosphate, by reducing Ca2+ activity or poisoning nascent crystals was determined. When apatite precipitated rapidly (1-4 h), glycocholate and taurine-conjugated bile salts (up to 100 mM) had little effect on apatite formation, but prevented amorphous calcium phosphate pre...

This article is a review of the published literature on apatite glass-ceramics (GCs). Topics covered include crystallization mechanisms of the various families of apatite GCs and an update on research and development on apatite GCs for applications in orthopedics, dentistry, optoelectronics, and nuclear waste management. Most apatite GCs crystallize through a homogenous nucleation and crystalli...

Computer modelling techniques were employed to investigate the effect of surface silanol groups on the strength of adhesion of apatite thin films to silica surfaces. To this end, we have studied a series of silica surfaces with different silanol densities and calculated their interaction with apatite thin films. Our findings indicate that apatite does not attach strongly to surface hydroxy grou...

Abstract Porous mullite ceramics were prepared from mixtures of Egyptian kaolinite-clay and calcined α-alumina powder. The effects two methods compaction as well types binder investigated. influence sintering temperature on the physical properties, crystalline phase, compressive strength microstructure was studied. Mullite bodies processed by uniaxial pressing utilizing 15wt. % water at 1500°C ...