thermal expansion?

Question

what is the significance of structures and machine components made of two materials with different coefficients of thermal expansion?

Answer 1

Typically, the difference is used in the thermostats in all your home appliances. Even in the older, pre-solid state, house thermostats. You just take two metals with different tempcos and laminate them somehow. When the piece is heated, it warps as one metal expands more than the other. The warping brings together the contacts of the thermostat. In something like an iron, it is built so that heating opens the circuit. The current for the iron is routed through the length of the thermostat. The current heats the thermostat, the contacts open, the iron cools, the contact closes. It is called a "bimetallic thermostat".

Answer 2

One interesting application of variable coefficients of thermal expansion is in the design of circuit breakers. With a strip of two dissimilar metals, as current is passed through, they will heat up. If the expansion is diffierent, it opens the circuit.

Answer 3

If two different materials are used in a component, they have different co-efficients of thermal expansion. so, the material selection is very much critical.
For (e.g), in an engine there are different parts / components.
Inlet and exhaust valves have different thermal co-efficients, they are selected in such a way. So, to compensate for these thermal co-efficients valve lash is given on higher side for exhaust valves.

Answer 4

linear expansion is the the difference in length of a material, after being subjected to heat each material has a different coefficient of linear expansion, ie copper, steel, plastic etc themal expansion of fluid such as water when boiled expands simples