глинозем ; окись алюминия
- This level of performance demands a very fine grained alumina with a grain size of below 4 m.
- In older patients this effect can cause bone loss and loosening of alumina based implants.
- As a result, an alumina implant can shield the surrounding bone from the stresses generated by normal activity, and the bone loses the stimulation which is necessary for it to remain healthy.
- Common to most ceramics, alumina does not cause adverse reactions on implantation and is generally classified as being inert, or nearly inert.
- A range of copper alloys has been found there and evidence suggests that lead was extracted from the copper by causing it to fuse with the silica and alumina in the clay crucible to form a lead-glass.
- It is the excellent wear characteristics of alumina which are the principal advantage in artificial hip systems.
- An additional problem when using alumina in load bearing situations is that its elastic modulus (380 GPa) is significantly higher than that of the cortical bone (72.5 GPa) with which it is in contact.
- Where do they get their partly refined alumina from?
- Cobalt oxide was calcinated with alumina to form the binary oxide cobalt aluminate (Co.Al 2 O 3 , known to artists as cobalt blue.
- Fine grain size also improves the mechanical strength and toughness of the alumina.
- Several adsorbents are available including silica gel, alumina, specially developed resins and activated carbon, the latter being the most important for odour removal, not being affected to the same extent by the presence of water vapour as are the other adsorbents.
- A further restriction on the clinical use of alumina is the response of tissues to its implantation.
- One of the first ceramics to be used in medicine was alumina; normally used for constructing the heads of artificial hips.