Bioceramics carbon

Calcium carbonate, mother-of-pearl, magnesite, dolomite and other inorganic materials which nature uses to provide an organism with solidity, have been categorized under the name bioceramic materials. Later some synthetic materials were added to this group. This means that the definition of a ceramic material, as given at the beginning of this book, must somewhat be adjusted as the heat treatment of a ceramic material obviously does not apply in the animal world. 

Several fluid bed processes are under development for production and encapsulation of nanoparticles, for example, WC-Co composites, bioceramics (i.e., calcium phosphate hydroxyapapite), carbon encapsulation of iron magnetic nanoparticles, and carbon nanotubes. These nano- or ultrafine powders have broad industrial and pharmaceutical applications. Production processes usually include solution preparation (sol-gel), drying, calcination, and sintering. The last three steps may be realized in a fluidized bed, but fluidization of nano- and ultrafine powders is very difficult because of strong interparticle forces. 

Bioceramics as Bone Substitutes The development of the so-called bioceramics is based on the knowledge that native bone is essentially composed of a more or less carbonated hydroxyapatite (HA) Caio(P04)(,(OH)2. With respect to the need for low solubility or of a controllable resorption, different compounds of the calcium phosphate system Ca(OH)2-H3P04-H20 have been applied for bone substitutes or bone fillings (Table 5.1). 

Nonabsorbable or Relatively Bioinert Bioceramics. 39-2 Relatively Bioinert Ceramics Alumina (AI2O3) Zirconia (Zr02) Carbons... 

Ceramics used in fabricating implants can be classified as nonabsorbable (relatively inert), bioactive or surface reactive (semi-inert) [Hench, 1991,1993] and biodegradable or resorbable (non-inert) [Hentrich et al., 1971 Graves et al., 1972]. Alumina, zirconia, silicone nitrides, and carbons are inert bioceramics. Certain glass ceramics and dense hydroxyapatites are semi-inert (bioreactive) and calcium phosphates and calcium aluminates are resorbable ceramics [Park and Lakes, 1992]. 

Carbon is an important bioceramic. It combines outstanding biocompatibility and chemical inertness. Carbon exists in many forms, some of which have been discussed in earlier chapters. The most important form of carbon... 

Huettner W, Carbon-fibre-reinforced carbon shaft-endoprosthesis - state of the art Ceramics in Surgery, Proc. 2nd Int. Symp, on Bioceramics, Lignano Sabbiadoro, Italy, 16-19 June, 1982, Vincenzini P ed., Amsterdam, Elsevier, 225, 1983. 

Prostheses. Artificial functional replacements for body parts, especially bones and joints. Ceramic materials for the latter are usually alumina, apatite or hydroxyapatite, and some glass-ceramics. Carbon composites have been used for heart valves. B.S. 7253 Pt. 2 specifies alumina bone substitutes. See bioceramics. 

Bioinert Relatively bioinert ceramics maintain their physical and mechanical properties while in the host. They are those stable bioceramics that do not react appreciably when they are implanted in the body. The implant does not form a bond with bone. Alumina (a-Al203) is a typical example of ceramic bioinert. Other examples, as we see next, are the zirconia ceramics (Zr02) and pirolitics carbon ceramics. 

Carbon presents a great variety of forms amorphous carbon, graphite, diamond, vitreous carbon and pyrolitic carbon. Some of them display the most excellent properties of biocompatibility, chemical inertia and thromboresistance that any other bioceramic. On the other hand, another advantage of these materials is that their physical characteristics are next to those of the bone [40]. Thus, their densities, according to the type carbon, change between 1.5 - 2.2 g/cm, and their elastic modules between 4-35 GPa. In spite of all the mentioned... 

Calcium phosphate bioceramics have drawn worldwide attention as the important substitute and scaffolding materials in hard tissue engineering due to their biocompatibility and bioactivity. This is due to the chemical similarity of these materials especially carbonated hydroxyapatite to the mineral constituent of bone [1-6]. 

Mata, D., Ohveira, RJ., Eerreira, N.M., Araujo, R.R, Fernandes, A.J., Lopes, M.A., Gomes, P.S., Fernandes, M.H., SUva, R.R, 2014. Processing strategies for smart electroconductive carbon nanotube-based bioceramic bone grafts. Nanotechnology 25, 145602. 

Murugan, R., Rao, K.P., and Kumar, T.S.S. (2002). Microwave synthesis of bioresorbable carbonated hydroxyapatite using goniopora. Bioceramics 15 51. ... 

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