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The thermal shrinkage is a physical phenomenon due to which matter, whether in solid, liquid or gaseous state, loses a percentage of its metric dimensions as temperature is removed.
In that sense, it is opposite to thermal expansion, characterized by the increase of proportions due to the energetic increase in the atoms of the matter product of the increase of temperature.
Both phenomena are due to the effect that the particles of matter have the injection or withdrawal of caloric energy, because it makes its atoms vibrate at a higher or lower rate respectively, thus requiring more or less space for movement.
This phenomenon is perfectly observable in gases, for example, whose volume responds to temperature, expanding and volatilizing in the heat, and contracting and even liquefying in the cold.
This type of phenomena are of Vital importance in the architectural and construction industries, since the choice of materials in the face of climatic conditions may well represent a problem in terms of the stability of buildings.
Finally, it should be noted that not all materials respond in the same way to expansion and contraction processes, and some even respond to only one of the two. For example, water expands when it is brought below 4 ° C.
Examples of thermal shrinkage
- Uncover jars. A known technique for uncapping metal-capped jars is to expand them using heat, since after spending a long time in the refrigerator or freezer, the metal contracts and it is much more difficult to turn it.
- The gas liquefaction. By cooling a gas to a certain point, a thermal contraction is induced such that its particles can change the structural arrangement between them and thus become a liquid. This process is known as smoothie and it is also usually produced through variations in pressure, forcing the particles to contract through environmental force.
- Water freezing. Water expands notoriously as it approaches its boiling point (100 ° C), and contracts as it descends to 4 ° C, acquiring its highest point density (greater closeness between its particles). Once below that temperature, it expands slightly again as it becomes a solid state.
- Thermal erosion. Exposure to the increase in temperature during the day and to the decrease at night, in cases of very high thermal variability, lead to the erosion of rocks and solid materials of the environment, which expand during the day and contract at night, thus promoting the loss of their customary density.
- Cold shrink assembly. In many manufacturing industries, complex pieces of machinery (flanges, pipes, pieces of lever) are assembled from their hot assembly, when they are expanded, since then, when they cool, the pieces will contract and remain firmly in place.
- Ceramic tiles. Ceramic for domestic use is very susceptible to expansion and contraction, and for this reason it is usually surrounded by an elastic application when fixing it in place, to keep it pressed in cases of contraction and cushioned in cases of expansion.
- Thermometers. Being a metal and also a liquid, mercury responds very well to thermal expansion, expanding in the heat and contracting in the cold, thus allowing changes in temperature to be seen.
- The roofs of the houses. During winter, construction materials tend to contract, causing deformations similar to those of their expansion during the summer. This is also due to the characteristic sound of wooden houses when this material cools and contracts at night.
- Thermal shock. Subjecting certain materials highly expanded by the action of heat to a sudden loss of temperature (a bucket of water, for example), will cause its rapid and violent contraction, thus generating cracks or fissures in the material.
- Glass handling. The famous experiment of how to put a whole boiled egg in a glass bottle is based on this principle. The glass is heated to expand it until the egg can pass through the mouth, and then it is cooled to contract it and restore it to its original dimensions.
It can serve you: Examples of Thermal Expansion
