| 摘要 |
Two-layer materials in the form of bimetal are known per se. By the joining together of two layers of materials with different coefficents of thermal expansion, bimetal strips assume different curvatures with changing temperatures and can thus be used as a temperature-dependent closed-loop or open-loop control element. However, the possible uses of bimetal are relatively restricted because of its other properties. Accordingly, the inventor has sought other two-layer materials which can be used for similar applications but with a greater scope. He has developed two-layer materials in which at least one layer consists of plastic and the other consists of a non-metallic material with a coefficient of thermal expansion which is as different as possible. In this case the two layers must have a high modulus of elasticity. The expansion coefficient of one layer must be zero or approximately zero, whereas the other layer has a high expansion coefficient. At least one of the layers must additionally have a shape-memory capacity. It has been found, surprisingly, that two-layer materials of this kind, in particular those with incorporated carbon fibres, have extremely good properties in the desired direction, so that they open up a multiplicity of fields of application which are closed to bimetallic closed-loop or open-loop control elements. <IMAGE>
|
