At present, strong requirements in orthopaedics are still to be met, both in bone and joint substitution and in the repair and regeneration of bone defects. In this framework, tremendous advances in the biomaterials field have been made in the last 50 years where materials intended for biomedical purposes have evolved through three different generations, namely first generation (bioinert materials), second generation (bioactive and biodegradable materials) and third generation (materials designed to stimulate specific responses at the molecular level). In this review, the evolution of different metals, ceramics and polymers most commonly used in orthopaedic applications is discussed, as well as the different approaches used to fulfil the challenges faced by this medical field.

https://royalsocietypublishing.org/doi/pdf/10.1098/rsif.2008.0151

Biomaterials in orthopaedics.

Handbook of SiC properties for fuel performance modeling

Porous structures having a continuous solid phase with isolated pores were prepared by the addition of different amounts of crushed naphthalene to an alumina casting slip. Samples of from 5 to 50% porosity were fired together for comparable grain development, eliminating structural variables except porosity. Effects of porosity and temperature on strength, elastic modulus, modulus of rigidity, and coefficient of thermal expansion were investigated. Effects of porosity on thermal stress resistance and tor-sional creep properties were studied at constant temperature.

Effect of Porosity on Physical Properties of Sintered Alumina

An empirical equation form, approximating the apparent dependence of the strength of brittle polycrystalline specimens on the combined effect of porosity and grain size, has been developed from concepts and data in the literature. The form is shown to be applicable to data for thoria and chromium carbide specimens.

Dependence of Mechanical Strength of Brittle Polycrystalline Specimens on Porosity and Grain Size

Expression for Effect of Porosity on Elastic Modulus of Polycrystalline Refractory Materials, Particularly Aluminum Oxide

The influence of controlled porosity on the compression strength of sintered pure alumina and of partly magnesia-stabilized zirconia was investigated. Bodies with porosities ranging from approximately 3 to 60% by volume were prepared utilizing hydrogen peroxide to induce pore formation. Cubes of approximately 1.2-cm, unit length were used in testing for compression strength at room temperature. The spatial arrangement of pores in sintered alumina was found to exert an influence, inasmuch as bodies with pores lined parallel to the pressure direction revealed a higher strength than bodies of the same porosity but with pores lined mainly perpendicular to this direction. It was found that an increase of porosity by 10 volume % decreased the strength of both sintered alumina and sintered zirconia by half of their initial respective values.

Compression Strength of Porous Sintered Alumina and Zirconia

Rigidity modulus of several sintered pure oxides was measured using specially prepared test pieces. A particular form of samples permitted an exact measurement of their dimensions and insured their proper elastic torsion deformation under a given load. Sintered alumina was tested up to 1550°C. Monocrystalline corundum, sintered stabilized zirconia, sintered pure beryllia, thoria, spinel, and zircon were tested at room temperature. Close agreement was noted between rigidity modulus values and Young's modulus values.

Eugene Ryshkewitch

Papers

Compression Strength of Porous Sintered Alumina and Zirconia

Rigidity Modulus of Some Pure Oxide Bodies 8th Communication to Ceramography