Physical Properties#
Density#
The mass of a material per unit volume.
Specific Strength#
The ratio of tensile strength to density, $ \frac{\sigma_b}{\rho} $.
Structural materials used in airplanes and spacecraft require high specific strength.
Ti, Al, and their alloys have high specific strength.
Specific Elastic Modulus#
The ratio of elastic modulus to density, $ \frac{E}{\rho} $.
Melting Point#
The temperature at which a material melts.
Crystalline materials have a fixed melting point, while amorphous materials do not have a fixed melting point.
Heat Capacity#
The change in heat when the temperature changes by $ 1^\circ C $ without a change in volume.
When a material transitions from one state to another, the internal atomic or molecular structure changes, resulting in a change in heat absorption (heat capacity) of the material. For example, when a material melts or vaporizes, it requires an input of heat from the surroundings, which indicates a change in heat capacity of the material.
Thermal Expansion#
Linear Expansion Coefficient#
The relative expansion of length caused by a temperature change of $ 1^\circ C $.
In general, ceramics have the smallest linear expansion coefficient, followed by metals, and polymers have the largest.
Thermal Conductivity#
The ability of a material to conduct heat.
Typically, metals and their alloys have much higher thermal conductivity than non-metallic materials.
Electrical Conductivity#
The ability of a material to conduct electric charge, expressed in terms of electrical conductivity or resistivity.
Metals and their alloys usually have good electrical conductivity, while ceramic materials and polymers are generally insulators.
Magnetism#
The ability of a material to be magnetized in a magnetic field.
The magnetism of a substance mainly includes diamagnetism, paramagnetism, and ferromagnetism.
Dielectric Constant#
The ability of a material to be polarized in an electric field.
Chemical Properties#
Corrosion Resistance#
The ability of a material to resist corrosion by a medium.
Ceramic materials and polymers usually have much higher corrosion resistance than metal materials.
High-Temperature Oxidation Resistance#
The ability of a material to form a continuous and firmly bonded film on the surface after rapid oxidation at high temperatures to prevent further oxidation.
Aging Resistance#
The resistance of polymer materials to aging.
Degradability#
The ability of plastics to rapidly decompose in a natural environment.
Technological Properties#
Castability#
The ability of liquid material to fill the mold and obtain high-quality castings during casting.
The quality of casting is related to factors such as the fluidity, shrinkage rate, and segregation of the liquid material.
Malleability#
The ability of a material to undergo pressure processing.
The malleability is mainly measured by the plasticity and resistance to deformation of the material.
Weldability#
The ability of a material to be easily welded together and ensure the quality of the weld.
The quality of weldability is usually evaluated by the tendency of various defects at the weld.
Machinability#
The ability of a material to be easily machined.
The machinability is related to the category, chemical composition, hardness, toughness, thermal conductivity, and internal structure of the material.
Materials with good machinability have easy cutting process, low tool wear, and smooth machining surface.
Under the same conditions, the machinability is closely related to hardness.
In general, the favorable hardness range for machining is 160-230HBS.
This article is synchronized to xLog by Mix Space.
The original link is https://nishikori.tech/posts/tech/Physical-chemical-and-technological-properties-of-materials