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A number of materials contract on heating within certain temperature ranges; this is usually called negative thermal expansion, rather than "thermal contraction".For example, the coefficient of thermal expansion of water drops to zero as it is cooled to 3.983 °C (39.169 °F) and then becomes negative below this temperature; this means that water has a maximum density at this temperature, and ...
For a single component system, the "standard" three parameters are the isothermal compressibility , the specific heat at constant pressure , and the coefficient of thermal expansion . For example, the following equations are true:
Systems do not contain work, but can perform work, and likewise, in formal thermodynamics, systems do not contain heat, but can transfer heat. Informally, however, a difference in the energy of a system that occurs solely because of a difference in its temperature is commonly called heat , and the energy that flows across a boundary as a result ...
The metals involved in a bimetallic strip can vary in composition so long as their thermal expansion coefficients differ. The metal of lower thermal expansion coefficient is sometimes called the passive metal, while the other is called the active metal. Copper, steel, brass, iron, and nickel are commonly used metals in bimetallic strips. [6]
This provides an expression for the Joule–Thomson coefficient in terms of the commonly available properties heat capacity, molar volume, and thermal expansion coefficient. It shows that the Joule–Thomson inversion temperature, at which μ J T {\displaystyle \mu _{\mathrm {JT} }} is zero, occurs when the coefficient of thermal expansion is ...
For example, heat capacity is an extensive property of a system. Dividing heat capacity, , by the mass of the system gives the specific heat capacity, , which is an intensive property. When the extensive property is represented by an upper-case letter, the symbol for the corresponding intensive property is usually represented by a lower-case ...
For example, if one were to mix a negative thermal expansion material with a "normal" material which expands on heating, it could be possible to use it as a thermal expansion compensator that might allow for forming composites with tailored or even close to zero thermal expansion.
A welding example involves heating and cooling of metal which is a combination of thermal expansion, contraction, and temperature gradients. After a full cycle of heating and cooling, the metal is left with residual stress around the weld.