Thermal properties-ceramics-refractory and abrasive material, Mechanical Engineering

Assignment Help:

Thermal Properties

Each solid expand on heating and convention on cooling. The thermal expansion of solids is due to basic structure whether atoms occupy mean position on a fixed distance from each other. In actual fact atoms are not stationary but vibrate about mean location or positions which changes along with temperature. The distance in between mean positions rises along with increasing temperature and reduces along with temperature. Such changes in the mean distance in between the atoms result in contraction or expansion. Coefficient of linear expansion is explained as the raise in length per till length per degree rise in temperature. For reduces in temperature similar property is regarded as -ive . The linear changes in three mutually perpendicular directions will constitute volume expansion coefficient. If the linear expansion coefficients in three orthogonal directions are equivalent then the solid is thermally isotropic. The thermal expansion is zero on absolute zero temperature and is usually related to exact heat and melting point of a substance.

This is interesting to notice that experiments express that total volume change on heating among absolute zero and melting point is same for each element. This implies that thermal expansion coefficient is low for high melting point solids. Most solids that are utilized for high temperature applications that are refractory materials have linearly varying thermal coefficients. The exception is silica as SiO2 and zirconia ZrO2 which due to polymorphic transformation implies irregular behaviour.

The coefficient of thermal expansion is significant consideration though designing structure to operate at high temperature. The limited deformations will reason forces to act upon the part and hence induce stresses. Further throughout moulding procedure proper care require to be exercised for volume's due consideration and linear changes after solidification hence dimensional accuracy and tolerances might be maintained. Apparently this consideration supposes greater significance in case of such materials that are not easy to machine. Ceramics and further refractory materials are illustrations.

                                   1809_Thermal properties.png

Figure: Thermal Expansion of Refractory Oxides as Function of Temperature

The coefficient of plastics of expansion might be controlled by addition of filler material; usually increasing filler material would reduce the coefficient. Expansion in instance of reinforced plastics tends to arise in the direction of reinforcement. There are a lot of plastics utilized in conjunction along with metals of common employ and it might be noted that employ of fillers enable material engineer to control the coefficient such plastic and metal expand equally. Unequal expansion will initiate undesirable deformation and stresses.


Related Discussions:- Thermal properties-ceramics-refractory and abrasive material

Explain applications welding process, Applications. The  welding  process ...

Applications. The  welding  process  finds  widespread  applications  in almost all branches of industry and construction. fabrication and creation of steel structures

Fluid friction, Fluid Friction: Fluid friction manifests when the lubr...

Fluid Friction: Fluid friction manifests when the lubricating fluid is introduced between contact surfaces of the two bodies. If thickness of lubricant or oil between the m

Expression for temperature distribution, Derive the mathematical expression...

Derive the mathematical expression for temperature distribution for plane wall with internal heat generation when both the surfaces are at same temperature?

Define plastics molding processes, There are various methods of producing c...

There are various methods of producing components from the plastics materials which are supplied in the granular, power and other forms. Various plastics molding processes discu

Stacking in the applicators storage, Q. Stacking in the Applicators storage...

Q. Stacking in the Applicators storage? Stacking in the Applicator's storage yard shall be in accordance with good safety practices and/or OWNER Specifications. Sufficient spac

Explain about master stick file, Q. Explain about Master Stick File? Th...

Q. Explain about Master Stick File? The Master Stick File is an up-to-date version of the P&IDs; it is not to be used as a check print by any discipline. Miscellaneous comment

Line of action of force, Line of action of force: Sol.: The directio...

Line of action of force: Sol.: The direction of force along the straight line through its point of application, in which force tends to move body to which it is applied. Thi

Reversible and irreversible processes - thermodynamics, Reversible and irre...

Reversible and irreversible processes: Thermodynamic system which is capable of restoring the original state of it by reversing the factors responsible for occurrence of proc

Larson-miller parameter, Larson-Miller parameter: For material of exam...

Larson-Miller parameter: For material of example of calculate life in hours at temperature of 900oC, and at σ = 20 MPa. Solution Larson-Miller parameter is given by

What is auto-ignition temperature, Q. What is Auto-Ignition Temperature? ...

Q. What is Auto-Ignition Temperature? Auto-Ignition Temperature (AIT) - The auto-ignition temperature is the temperature at which a product will burn without application of any

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd