Silicon dioxide occurs naturally in oceans, plants and rocks – including most of the earth’s crust – and in humans where it plays an essential role in bone development and maintenance.
Silicon carbide was first mass-produced on an industrial scale by Acheson in 1891 and marketed under the trade name Carborundum. This material is noncombustible and generally nonreactive. However, molten alkalis and iron solutions dissolve it.
Silicon Dioxide
Silicon dioxide (SiO2) is a chemical compound with the formula SiO2. Most often found as quartz crystals, silicon dioxide can be found naturally everywhere from waterways and bodies of water to plants, animals, rocks and beaches – it makes up 95-97% of Earth’s rock mass!
Assuming it’s taken orally, silica dust is generally non-toxic; however, inhaling finely divided particles can increase your risk of bronchitis, lung cancer or silicosis due to lodgement in your lungs; additionally it increases rheumatoid arthritis and lupus risk significantly.
Food grade silicon dioxide (amorphous or colloidal) is frequently employed as an anti-caking agent to keep powdered food products from clumping together, as well as being added to supplements due to its absorbent, disintegrant and glidant properties.
Silicon dioxide (SiO2) is an inert solid that resembles talcum powder in appearance and composition, and it dissolves only in acidic media – not alkali solutions or alcohols. Silicon dioxide belongs to the family of silicates, and may exist in various crystal forms.
Silicon dioxide reacts with all halogens to form silica tetrahalides and with hydrofluoric acid to produce hexafluorosilicic acid, both essential raw materials in electronic, chemical and pharmaceutical industries. Silicon dioxide is also an integral component in glass production; used to make borosilicate glass, soda-lime glass and lead glass production as well as ceramics, porcelain enamel paint additives corrosion inhibitors textile glazes insulators. Silicon dioxide also has applications as ceramic coating material on copper alloy surfaces.
Food Additives
Food additives come in all sorts of varieties; their purpose is to streamline food from factories or kitchens through warehouses and shops and ultimately into people’s homes more quickly. While some, such as monosodium glutamate (MSG), may cause adverse health issues in small amounts, others such as silicon dioxide can be considered safe when consumed as food additives.
Most food additives are manufactured synthetically; some naturally occuring additives also exist. Food additives serve a number of functions in food production and storage processes – they provide more nutrients, are safer to store, keep its appearance appealing and ensure processed foods stay safe throughout their journey from factories and industrial kitchens to warehouses, shops and restaurants.
Before any additive can be added to food, our scientists at the European Food Safety Authority (EFSA) and Joint FAO/WHO Expert Committee on Additives (JECFA) must conduct tests evaluating its safety. Once safety has been verified, national regulations must allow its implementation into food products.
Food grade additives must be listed with their E number in food labels and ingredients lists, to indicate their approval for use. EFSA scientists are reviewing some additives found to be safe by JECFA for further review by re-evaluation; interested business operators are invited to submit new scientific evidence or data and help reevaluate these substances.
Ceramics
Ceramics are durable materials that can be formed into shapes before being heated at very high temperatures for firing. Ceramics can be used as containers, shields and components of high-tech devices before being fired at very high temperatures to form hard bodies with solid properties. Their main applications are containers, shields and components in high tech devices; bone replacement materials; dental implants. Their raw materials include clay, silica and feldspar which is mixed into green bodies before heating to extremely high temperatures in oxygen-free atmospheres to produce solid bodies from its constituent ceramic materials fusing together into solid bodies made of its constituent materials creating solid bodies from its constituent components; eventually producing solid bodies with solid bodies being formed from its constituent ceramic materials fusing into solid bodies formed from tiny grains of constituent materials becoming one solid body.
Silicon carbide boasts the highest strength at high temperatures, making it suitable for applications such as mechanical seals and pump parts. Furthermore, its corrosion-resistance is unrivaled; furthermore its wear resistance exceeds that of most advanced ceramics such as alumina and zirconia. Its thermal conductivity rating falls between that of other advanced ceramics but higher than alumina or zirconia.
Porous silicon carbide (p-SiC) is an advanced material with high specific surface area and pore volume but low direct current electrical conductivity, making it an attractive candidate for use in nanotechnology due to its unique morphology and thermal expansion coefficient.
Gelation-freezing technique was recently developed to produce p-SiC ceramics with uniformly aligned micrometer-sized pores. This process involves dispersing raw powder in water to form a wet gel before freezing in cold ethanol and sublimating without shrinkage of green body to obtain ceramics with high porosity (87%) and uniform pore structures.
Bone Replacement
Needing bone replacement after fracture or trauma necessitates procedures like graft surgery. Traditional allografts or autografts come from allogeneic or autogenous sources; alternatively there are synthetic bone grafts which are much simpler and don’t cause an antigenic response, as well as customized to any application imaginable. In either case it must also promote new bone formation in their areas of placement by being osteoconductive – encouraging new bone to form where placed.
Bioactive SiC has demonstrated great promise as a bone replacement material. Its porous structure mirrors that of human bone, while having excellent mechanical properties. The microstructure is created through infiltration of molten-Si into carbon templates obtained through controlled pyrolysis of wood, creating biomorphic silicon carbide (BSC). With 30% to 70% porosities available this process produces biomorphic silicon carbide (BSC).
BSC boasts a high oxygen content, making it conducive to bone cell growth. Furthermore, its 3D connected structure and excellent biocompatibility make this material suitable for human osteoblast proliferation stimulation and proliferation testing. BSC material comes either as foam or ceramic coating and has been shown to stimulate primary human osteoblast proliferation comparable to porous hydroxyapatite ceramics; however degradation and formation aren’t coordinated properly and stimulating osteoclastogenic growth factors could provide a way to address this mismatch.
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