A-level Activated Science Allotment and Using Abstracts Classes of abstracts

 26 July 12:40   

    Materials can be aggregate into classes according to their composition. You should know:

    You should be able to:

    For anniversary chic of material, you will charge to accord examples of their uses, with justification:

    (“X is acclimated for Y because it is A, B and C.”

    e.g. Chestnut is acclimated for calm base because it has a low electrical conductivity, is adjustable and cheap.)

    Consider uses such as

    Metals are apparent abstracts with the abnormally aqueous brownish bonding. The chargeless electrons of brownish bonding create metals cogitating and electrically- and thermally conductive.

    The brownish bonding makes the anatomy able to sustain strain. Metals are can be hard, but are aswell adaptable and tough. They are able if subjected to all sorts of stress.

    Metals can be shaped if algid (they are plastic/ductile) or broiled and formed into new shapes by casting (they are thermoplastic).

    Ceramics are apparent materials. As such, they tend to be opaque.

    The bonding is ionic or covalent, which makes the anatomy clumsy to sustain strain. Ceramics are hard, adamant and brittle. They are able if subjected to compressive stress, but not to compactness accent or accustomed stress.

    Ceramics are formed by the actinic acknowledgment of artificial precursors e.g. clay. Already formed, they cannot be re-moulded i.e. they are thermoset.

    Glasses are baggy materials: They accept no clear structure. Glasses are baggy ceramics but it is accessible to create baggy metals and baggy polymers.

    Being amorphous, glasses are transparent. Their backdrop are agnate to ceramics except that they are thermoplastic.

    Polymers can be apparent or amorphous. Baggy polymers tend to be bright admitting apparent ones are opaque.

    Crystalline polymers are anisotropic: Their backdrop alter depending on whether they are activated forth their polymer chains (strong, rigid) or beyond the chains (weak, ductile).

    Amorphous polymers accept boilerplate backdrop in all admonition of testing (they are isotropic).

    Thermoplastic polymers abide of continued chains, which if acrimonious will become aqueous and can then be re-moulded to new shapes.

    Some thermoplastic polymers accept such able intermolecular bonding that the calefaction appropriate to cook them is added than the calefaction appropriate to create them combust. These behave like thermoset polymers.

    Thermoset polymers are like ceramics: They are formed from aqueous precursors but anatomy a abiding 3D filigree of covalent bonds which is absurd to melt. Like ceramics, thermoset polymers are brittle. Clashing ceramics, thermoset polymers are softer, beneath close and abundant beneath calefaction resistant.

    ; Steel-reinforced accurate : Accurate has accomplished attrition to compressive stress, and is bargain and durable. Animate is big-ticket and corrodes but has accomplished attrition to compactness and accustomed stresses.

    ; Carbon fibre able artificial

    : Plastics are boxy but flexible. Carbon fibre has amazing compactness backbone but little attrition to compressive or accustomed accent (it buckles). Both abstracts are actual low density.

    : Accumulation artificial and carbon fibre gives a tough, strong, failing material. By capricious the administration of braid of the carbon fibre, the backdrop can be create anisotropic. If a fibre breaks, the artificial transfers the accent to additional fibres.

    ; Plywood

    : Copse is anisotropic – it is ample weaker to stresses which are compactness or accustomed to the atom of the wood.

    : Plywood has layers of copse at appropriate angles, so that accent in any administration is compactness to the atom of some layers of wood. The cement which binds the plywood aswell adds to its strength.