Coefficient of thermal expansion

The coefficient of thermal expansion is used:

in linear thermal expansion
in area thermal expansion
in volumetric thermal expansion

These characteristics are closely related. The volumetric thermal expansion coefficient can be measured for all substances of condensed matter (liquids and solid state). The linear thermal expansion can only be measured in the solid state and is common in engineering applications.

Thermal expansion coefficients for some common materials

The expansion and contraction of material must be considered when designing large structures, when using tape or chain to measure distances for land surveys, when designing molds for casting hot material, and in other engineering applications when large changes in dimension due to temperature are expected. The range for α is from 10^-7 for hard solids to 10^-3 for organic liquids. α varies with the temperature and some materials have a very high variation. Some values for common materials, given in parts per million per Celsiusdegree: (NOTE: This can also be in kelvins as the changes in temperature are a 1:1 ratio)

coefficient of linear thermal expansion α
material	α in 10^-6/K at 20 °C
Mercury	60
BCB	42
Lead	29
Aluminum	23
Brass	19
Stainless steel	17.3
Copper	17
Gold	14
Nickel	13
Concrete	12
Iron or Steel	11.1
Carbon steel	10.8
Platinum	9
Glass	8.5
GaAs	5.8
Indium Phosphide	4.6
Tungsten	4.5
Glass, Pyrex	3.3
Silicon	3
Invar	1.2
Diamond	1
Quartz, fused	0.59

Applications

For applications using the thermal expansion property, see bi-metal and mercury thermometer

Thermal expansion is also used in mechanical applications to fit parts over one another, e.g. a bushing can be fitted over a shaft by making its inner diameter slightly smaller than the diameter of the shaft, then heating it until it fits over the shaft, and allowing it to cool after it has been pushed over the shaft, thus achieving a 'shrink fit'

There exist some alloys with a very small CTE, used in applications that demand very small changes in physical dimension over a range of temperatures. One of these is Invar 36, with a coefficient in the 0.6x10^-6 range. These alloys are useful in aerospace applications where wide temperature swings may occur.

Comments

what is velocity?

what is velocity? Velocity is a vector expression of the displacement that an object or particle undergoes with respect to time . The standard unit of velocity magnitude (also known as speed ) is the meter per second (m/s). Alternatively, the centimeter per second (cm/s) can be used to express velocity magnitude. The direction of a velocity vector can be expressed in various ways, depending on the number of dimensions involved. Velocity is relative. Consider a car moving at 20 m/s with respect to the surface of a highway, traveling northward. If you are driving the car, the velocity of the car relative to your body is zero. If you stand by the side of the road, the velocity of the car relative to you is 20 m/s northward. If you are driving a car at 15 m/s with respect to the road and are traveling northward, and another car moving 20 m/s with respect to the road passes you in the same direction, that other car's velocity relative to you is 5 m/s northward. But if t

Crystallinity

Crystallinity Crystallinity is a physical property of a solid that acts like a crystal . The degree of crystallinity of a crystal has a big influence on hardness , density , transparency and diffusion . Crystallinity can be measured using x-ray diffraction , but calorimetric techniques are also commonly used. Examples would include: sodium chloride (table salt) aspakdonad Fiverr Seller Hi Friends Iam Mohamed Aspak And Iam studying in B.E Computer Science&Engineering Student 2nd Year And I need to work online In part time. I know Full editing of Photos and videos. i will Do my Extreme Best For Your Orders.I Can do Your Project within 2 or 4 hours And having youtube channel... :-)

Momentum

Momentum Momentum can be considered the "power" when an object is moving, meaning how much force it can have on another object. For example, a bowling ball (large mass) pushed very slowly (low velocity) can hit a glass door and not break it, while a baseball (small mass) can be thrown fast (high velocity) and break the same window. The baseball has a larger momentum than the bowling ball. Because momentum is the product of the mass and the velocity of an object, that both mass and velocity affect the momentum of an object. As shown, an object with a large mass and low velocity can have the same momentum as an object with a small mass and large velocity. A bullet is another example where the momentum is very-very high, due to the extraordinary velocity. Another beautiful example where very low-velocities cause greater momentum is the push of Indian subcontinent towards the rest of Asia, causing serious damages, such as earth quakes in the portions of himalayas. In this ex

Time Machine

Search This Blog