Hydrotalcite-type anionic clays: Preparation, properties and applications.

Ceramics used for the repair and reconstruction of diseased or damaged parts of the musculo-skeletal system, termed bioceramics, may be bioinert (alumina, zirconia), resorbable (tricalcium phosphate), bioactive (hydroxyapatite, bioactive glasses, and glass-ceramics), or porous for tissue ingrowth (hydroxyapatite-coated metals, alumina). Applications include replacements for hips, knees, teeth, tendons, and ligaments and repair for periodontal disease, maxillofacial reconstruction, augmentation and stabilization of the jaw bone, spinal fusion, and bone fillers after tumor surgery. Carbon coatings are thromboresistant and are used for prosthetic heart valves. The mechanisms of tissue bonding to bioactive ceramics are beginning to be understood, which can result in the molecular design of bioceramics for interfacial bonding with hard and soft tissues. Composites are being developed with high toughness and elastic modulus match with bone. Therapeutic treatment of cancer has been achieved by localized delivery of radioactive isotopes via glass beads. Development of standard test methods for prediction of long-term (20-year) mechanical reliability under load is still needed.

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Bioceramics: From Concept to Clinic

Bioceramics : from concept to clinic

A brief history and review of geopolymer technology is presented with the aim of introducing the technology and the vast categories of materials that may be synthesized by alkali-activation of aluminosilicates. The fundamental chemical and structural characteristics of geopolymers derived from metakaolin, fly ash and slag are explored in terms of the effects of raw material selection on the properties of geopolymer composites. It is shown that the raw materials and processing conditions are critical in determining the setting behavior, workability and chemical and physical properties of geopolymeric products. The structural and chemical characteristics that are common to all geopolymeric materials are presented, as well as those that are determined by the specific interactions occurring in different systems, providing the ability for tailored design of geopolymers to specific applications in terms of both technical and commercial requirements.

Geopolymer technology: the current state of the art

Changes in portlandite morphology with solvent composition: Atomistic simulations and experiment

WE have prepared porous microstructures, having potential for prosthetic applications, consisting of hydroxapatite and of whitlockite, by employing exchange reactions at elevated temperatures and pressures. Rather demanding specifications are to be met by biomaterials being considered for tooth or bone replacement. Porous solids have the advantage of allowing circulation of body fluids and of increasing the potential for firm attachment of body tissue1,2. Weber et al.3 successfully replicated the porous structure of echinoid skeletal material in epoxy resin and in sodium silicate; and White et al.4 achieved replication of the coral Porites structure with methacrylate, tin, Tichonium, and sintered Al2O3. This was the starting point for our attempts to reproduce such structures in the phosphatic material which is a major component of human teeth and bones, hydroxyapatite. Such a material, porous, inorganic and sterile (formed at high temperatures and pressures), should be highly compatible with body tissue, and when used as bone implants may become essentially integral with the bone. Furthermore, composites of such porous hydroxyapatite with other materials including metals4 may achieve optimum mechanical and physical properties for a particular application.

Hydroxyapatite formed from Coral Skeletal Carbonate by Hydrothermal Exchange

Alkali-activated cements Opportunities and challenges

Ettringite and CSH Portland cement phases for waste ion immobilization: A review

Effect of silica fume, metakaolin, and low-calcium fly ash on chemical resistance of concrete

New cements developed in recent years have strengths that are greater by an order of magnitude than those of conventional hydraulic cements. These low-temperature materials, whose strengths approach those of many traditional high-temperature ceramics, are termed chemically bonded ceramics. The different routes to generating strong cementitious materials, including warm pressing, chemical modification, high-shear mixing with polymer additions, and the making of fiber and particulate composites, are reviewed. Strength, toughness, durability, impermeability, and abrasion resistance of these new materials have been greatly improved, as have certain electrical and acoustical properties.

https://science.sciencemag.org/content/sci/235/4789/651.full.pdf

Della M. Roy

Papers

Hydroxyapatite formed from Coral Skeletal Carbonate by Hydrothermal Exchange

Alkali-activated cements Opportunities and challenges

Ettringite and CSH Portland cement phases for waste ion immobilization: A review

Effect of silica fume, metakaolin, and low-calcium fly ash on chemical resistance of concrete

New strong cement materials: chemically bonded ceramics.