V. A. Dubok

Bioceramics ― Yesterday, Today, Tomorrow

Developments and applications of bioceramics are reviewed. Used initially as alternatives to metallic materials in order to increase the biocompatibility of implants, bioceramics have become a diverse class of biomaterials presently including three basic types: bioinert high-strength ceramics; bioactive ceramics which form direct chemical bonds with bone or even with the soft tissue of a living organism; various bioresorbable ceramics which are actively included in the metabolic processes of an organism with predictable results. Certain members of the different types of bioceramics are the most bioinert and biocompatible of all known biomaterials. A review of the composition, physicochemical properties, and biological behavior of the principal types of bioceramic materials is given, based on the literature and some of our own data. The materials include, in addition to classical sintered ceramics, bioglass-ceramics and bioglasses which are similar in composition, properties, and applications. Special attention is given to structure as the main physical parameter determining not only the properties of the ceramic materials, but also their reaction with the biomedium. The present status of research and development in bioceramics is characterized as a first step in the solution of complex problems at the confluence of materials science, biology, and medicine by the synthesis of “smart materials.”

Microstructure and porosity of zirconium dioxide powder compacts produced at pressures up to six GPa

One of the basic problems in the production of modern high-tech ceramics is the formation, from the initial ultrafine powder, of compacts with maximum uniformity and minimum pore size [i]. Nonuniformities residing in the nature of the powders themselves represent a serious obstacle in accomplishing this. in order to eliminate these, high pressing pressures, sufficient to completely disintegrate the powder, are necessary. The use of powders with weak, easily fragmented agglomerates is also recommended, in both cases evaluation of the strength of agglomerates and other structural elements of the powder is necessary, for which purpose the dependence of its density on the logarithm of the applied pressure is employed [2-4]. This dependency consists, as a rule, of two linear parts with different slopes, increase of the slope at increased pressure is explained by a change in the mechanism of disintegration of the particles: transition from fragmentation and regrouping of agglomerates to their fracturing as a result of multidirectional compression [4].