Definition
Grouping of engineering materials based on class divides them into groups such as metallic materials, ceramic materials, materials made of polymer, composite materials and electronic materials Metallic materials are strong and ductile at room temperature. Their strength even a high temperatures remains high, and they have high electrical and thermal conductivities. Polymeric materials are poor electrical and thermal conductors, the have low to medium strengths, have low densities, they are easy to process into final shape and some of them are transparent. Ceramic materials have high hardness, are mechanically brittle, have high temperature strength and have poor electrical and thermal conductivities. Composite materials have a wide range of strength, and they have very useful strengths at a low cost. Electronic materials are light in weight, can transmit electrical signals in a complex manner and they are energy efficient. In terms of the electrons in an atom, the materials may either be of solid solution or of crystal defects and non-crystalline structure. Those of solid solution are said to have chemical imperfection while the latter are said to have imperfection.
Physical properties
Density is the mass per unit volume of the material and is represented as a ratio. Its unit in the SI system is Kg/m3. Thermal conductivity is a measure of the ability of a material to conduct heat and is denoted by k/ lambda/ kappa. Heat transfer takes place at a lower rate in materials of low thermal conductivity and the vice versa is also true. Electrical conductivity of materials is a property which represents how easily electricity can be conducted by the material. It is the reciprocal of resistivity of material and its unit is mho/meter. Super conductivity refers to the disappearance of electrical resistance in various solids when cooled below a characteristic temperature ( transition temperature) which varies according to the material but is usually below 20K. Specific heat of a material is the amount of heat required to increase the temperature of unit mass of material by one degree Celsius and is denoted by the letter S. Its unit in SI system is Joule/kg 0C. Melting range is the difference in temperatures from the point at which crystals first begin to liquefy to the point whereby the entire sample is liquid.
Thermal expansion refers to the tendency of matter to change its shape, area, volume and density in response to a change in temperature with the exception of phase transitions. Magnetic properties of engineering materials may be divided into four. Paramagnetic materials are weakly attracted by the magnet, ferromagnetic materials are strongly attracted by the magnetic field, antiferromagnetic materials have a net magnetic moment of zero while ferromagnetic materials have small magnetic moments. The optical properties of an engineering material defines its interaction with light. The four optical properties that are mostly considered are refraction, absorption, reflection, and scattering of light. Corrosion resistance is the ability of a material to hold the binding energy of a metal and withstand deterioration and the chemical breakdown that would occur when the material is exposed to such an environment. Phase transformations usually occur when a material changes its composition and structure. Such a transformation may be due to temperature changes or due to reaction with another material. Fluidity refers to the ability of a substance to flow easily and the state of the material to be and remain fluid.
Mechanical properties
When a material is stressed by an amount that is less than its yield stress, it will go through a reversible strain and no permanent deformation of the material will occur. The level of stress corresponding to the yield point is the yield strength of the material. Tensile strength of a material is the maximum load it can support without fracture when being stretched by the original cross-sectional area of the material. Shear strength is the ability of the material to resist forces that may cause the internal structure of the material to slide against itself. Elongation is a measure of deformation that occurs before a material breaks due to subjection to a tensile load. Young’s module is a property of engineering materials that tells how easily it can stretch and deform. It is defined as the ratio of tensile stress to tensile strain. Modulus of rigidity is the measure o rigidity of a body and is expressed as a ratio of shear stress to shear strain.
Ductility refers to the degree to which a material can sustain plastic deformation under tensile stress before failure. Impact strength refers to the resistance of a material to fracture by a blow and is expressed in terms of the amount of energy absorbed before fracture (Jansen). Fatigue resistance is the measure of the bearing’s strength regarding combustion engines where the loading takes a cyclic direction and intensity. Hardness is the measure of how much a material resists changes in shape while failure analysis is carrying out an investigation to determine the cause of failure with an aim of taking action to correct the problem and prevent future failures. Malleability is an important factor for materials to have as it determines how they may be altered by external forces hence change in shape.
Manufacturing process
Hardenability is a step in the manufacturing process involves hardening the engineering material to a certain depth by passing it through a heat treatment process. It is followed by precipitation hardening which makes use of the heating application to make the material tougher. This makes the material strong as it is hardened by adding solid impurities (precipitates) ( Fukumoto). Annealing also involves a heating process that changes the physical and sometimes the chemical properties of a material to increase its ductility and reduce hardness hence making it more workable. Cold work does not require any ignition and it involves plastic deformation that is caused by pressing and rolling at room temperature. Heat treatment involves heating a metal while at the same time ensuring it does not reach its molten stage and then cooling it controllably to select its desired mechanical properties (Sarma 561-564). Machines are involved in each step of the manufacturing process to ensure proper conversion of raw materials into the required finished products.
Materials and environment
Most of the engineering materials are acquired from the natural environment and help to improve in the construction works for the improvement of the economy. However, it is important for the people involved to acquire these materials in moderation to prevent harming the environment. Increased acquisition of wood, for example, may lead to increased deforestation and hence increased spread of drought and famine. Proper knowledge on the life cycle and sustainability of materials enables the engineers involved to measure how long a certain material can serve the construction work it is involved in. Once this time is not put into consideration, the material may end up harming the environment and causing damages to the construction work. It is also vital for the engineer to be credible in his/her job to be able to appropriately select materials which are good for the environment and the work at hand. He/she should also be in a position to differentiate the renewable and non-renewable materials as improper use of these materials may lead to devastating effects on the environment such as climate change. Even as these factors are put in place, they may not be effective if the legislations put in place in conservation of materials are not adhered to or followed strictly. The legislators should put in place laws that benefit the environment and ensure harsh punishments for those who go against these laws.
Cost analysis
It is important for the engineer to have a step by step break down of the resources that are likely to be used in the construction work and calculate the cost of each of them. He/ she should also leave room for excess resources to be used and include that in the calculation. The engineering design process should also be considered to determine which materials will be used more and hence the necessary calculations to be made. Development scaling usually involves a concept that includes laboratory testing, pilot scale testing and the production scale. All these processes ensure the materials used produce high quality work and they do not deteriorate within a short period after completion of the project. The concept of the economy of scale helps the engineer to match the materials with their existing prices in the market to accurately determine how much to put aside regarding the materials. Cost estimation is important before the construction works begin to prevent misusing the finances or running out of these finances before completion of the work.
Works Cited
Fukumoto, Ken-ichi. Irradiation hardening behavior of he-irradiated V-Cr-Ti alloys with low Ti addition. Quantam Beam Science 5(1), 2020.
Jansen, Victor. The relation between impact strength and flexural strength of materials. Journal of Mechanical Behavior of Engineering Materials, 2021.
Sarma, Jitupan. Enhancement of material properties through heat treatment process. Materials Today: Proceedings 23, 2020.
Zingales, Massimiliano. Advanced materials modelling via fractional calculus. Philosophical Transactions of the Royal Society, 2020.