Material selection is determined by capabilities and qualities of materials or their properties. These properties are also used to help specify and identify metals. This engineering material determine utility of material to get response with given material to impose stimuli and constraints. There is various engineering material properties are given as under. Let us discuss about properties of materials.
Types of Properties of Engineering Materials
Materials have different properties depending on what they are used for. Some materials are hard, others are soft. These are types of materials most commonly used in everyday life are given below.
- Physical Properties of Materials
- Chemical Properties of Materials
- Thermal Properties of Materials
- Electrical Properties of Materials
- Magnetic Properties of Materials
- Optical Properties of Materials
- Mechanical Properties of Materials
These properties of material are discuss as under
Physical Properties of Materials
Physical properties of material are those which can be observed without change of identity of material. Physical properties of metals are density, color, size and shape, specific gravity of material, porosity etc. Some of these are defined as below. We should have knowledge of physical properties of materials.
Density of Materials
Density is one of most fundamental physical properties of any material. Density of material is defined as mass per unit volume. It is defined as ratio of mass volume of material. It is denoted by “p”. Its unit in SI system is KG/m3. Density is an important in many calculations because most designs are limited by either size or weight.
Shape and Size
Dimension of any metal reflect shape and size of material, length, width, height, depth etc. Also, it determines specific rectangular, circular, spherical, or any other section. You can also read Engineering Materials – Atomic Structure Introduction.
Specific Gravity of Materials
It is defined as ratio of density of material with respect to density of reference material or substance. It does not have any unite. Sometimes it is also called as relative density. For gravity calculation water is considered as reference substance.
Porosity of Materials
When material is in melting condition, it contains some dissolved gases with in material. When material is solidifies these gases get evaporate and leave behind voids. Porosity of materials represents quantity of voids in solid materials.
Chemical Properties of materials
Chemical properties related to changes in chemical composition of material because it interacts with other substances. Chemical properties of engineering materials are needed because most of materials, when they come in contact with other substances can react to form new materials. It is deterioration of material by chemical reaction with its environment.
It cannot be observed without changing chemical composition of substance. This chemical property includes pH, production of salt when an acid reacts with metal or unique color change in chemical reaction.
Thermal Properties of materials
Engineering materials are important in everyday life because of their versatile structural properties. Thermal properties of engineering materials are diverse and so their uses in different applications. Thermal properties are those properties of material which is related to its conductivity of heat.
In other words, these are properties which are display by material when heat is passed through it. Thermal properties of material refer to characteristic behaviors of material under thermal load. Other than these properties, they do play an important role because of their physical properties.There are different thermal properties are thermal conductivity, thermal expansion, specific heat, melting point, thermal diffusivity.
Melting point is temperature at which material goes from solid to liquid state at one atmosphere. Melting point states as transition point between solid and liquid phases. Melting point is temperature at which pure metal or compound changes its state from solid to liquid.
Melting temperature depends on inter-atomic and intermolecular bonds nature. Therefore higher meting temperature is show by those materials possessing stronger bonds. Covalent, ionic, metallic and molecular are types of solids and they decrease order of bonding strength and melting point.
Electrical Properties of engineering materials
Electrical properties are their ability to conduct electrical current. Various electrical properties are resistivity, Electrical conductivity, temperature coefficient of resistance, dielectric strength and thermoelectricity.
Some of electrical properties of engineering materials are below
It is property of material which resists flow of electric current through material. It is give-and-take of conductivity. Resistivity values are reported in micro ohm centimeters units. As mentioned above resistivity values are simple give and take of conductivity.
It is property of material with allow flow of electric current through material. It is parameter which indicates that how easily electric current can flow through material. Conductivity of material is give and take of resistivity. Electrical conductivity measure of how well material accommodates movement of an electric charge. It is ration of current density to electric field strength.
Electrical conductivity is very useful property since values are affected by such things. Therefore, electrical conductivity information can be used for measuring purity of water, checking for proper heat treatment of metals and inspecting for heat damage in some materials.
It is property of material which indicates ability of material to withstand at high voltages. Usually, it is specified for insulating material to represent their operating voltage. Which material having high dielectric strength can withstand at high voltages.
Temperature Coefficient of Resistance
Temperature coefficient of resistance of material indicates change in resistance of material with change in temperature. Resistance of conductor changes with change of temperature. As noted above, electrical conductivity values are reported at 20 degree centigrade. This is done because conductivity and resistivity of material is depending on temperature. Thus conductivity of materials decreases as temperature increases.
If link formed by joining to two metals is heated, a small voltage of millivolt is produced. This effect is called thermoelectricity or thermoelectric effect. This effect forms basis of operation of thermocouples and some temperature based transducers. This can be used to generate electricity, to measure temperature and to measure change is temperature of objects.
Magnetic Properties of Material
Origin of magnetism lies in orbital and spin motions of electrons and how electrons interact with one another. Magnetic properties of material are those which determine ability of material for particular magnetic application. Read Engineering Materials – Deformation of Solid Materials
It is property of magnetic material which indicates that how easily magnetic flux is build up in material. It is determined by ratio of magnetic flux density to magnetizing force producing this magnetic flux density.
Magnetic Hysteresis is an important material by which is firstly becomes magnetized and then de-magnetization process. Lack of retrace ability of magnetization curve is called hysteresis and is related to existence of magnetic domains in material. Magnetic hysteresis is rising temperature at which given material ceases to be ferromagnetic, or falling temperature at which it becomes magnetic.
This force defined as magnetizing force which is essential to neutralize completely magnetism in an electromagnet after value of magnetizing force become zero. Also read Engineering Materials -Comparison between Crystal Slip and Twinning
Optical properties that define material response to incident radiation can be described as transmission, reflection and absorption. Every solid material emits thermal radiation. This
Mechanical properties of material help us to measure how materials behave under load. In order to achieve optimal system performance, mechanical properties include density, hardness and elasticity. Mechanical properties of material reflect relationship between its response to and deformation from an applied load or force. Properties of materials that find out its behavior under applied forces are called mechanical properties.