Properties And Modern Application Of Engineering Materials

Describe about the Report for Properties and Modern Application of Engineering Materials.

 

Engineering materials are imperative in everyday life owing to their versatile structural characteristics. Other than their characteristics, they do play a significant role due to their physical characteristics. The prime physical properties of the commonly utilized engineering materials include electrical, thermal, magnetic, and optical properties as discussed in the report. This is a report on the properties of materials and the influence they have on their use and application in modern engineering. The report includes mechanical, electrical, optical, thermal, and alloying properties and the pros and cons of each, giving examples in each case.

1. Mechanical properties of materials

 These are those proprties that determine the mechanical strength of a material and its ability to be molded in appropriate shape. Some of the common mechanical properties include strength, hardenability, ductility,creepand, slip resilience, brittleness, malleability, toughness, hardness, and fatigue (Kakani, & Kakani, 2004).

Strength

It is the material’s characteristic that its tendency to deform or undergo breakdown when an external force or load is applied. The material to be considered as for any engineering product should have an appropriate  mechanical strength to be able to bear varying mechanical loads and forces.

Toughness

This is the capability of an enginerring material to absorb and withstand the applied energy and undergo plastic deformation without experiencsing any fracture. The numerical value of toughness is estimated by the value of energy in a unit volume measured in J/ m³. Also, the value of a meterial’s toughness can be estimated by stress-strain properties of the material. For any material to possess desirable toughnes,it should possess suitable ductility  and strength. For instance, brittle materials that possess excellent strength but undesirable ductility do not have desirable toughness. On the other hand, materials that have excellent ductility but undesirable strength similarly do not possess desirable toughness. Thus,  for a meterial to be tough, it should be able to withstand both elevated stress and strain (Wigley, 2012).

Ceramics have gained versatile application in the field of engineering. Products made using technical ceramics are renown components in the construction and control of complicated plants, machinery, and equipment that require electro-technical component assemblies (Munz, & Fett, 2013). Common examples are λ sensors in the automotive engineering industry or in the furnace/ kiln engineering. Others are the vacuum chambers of actuators in motion detectors.

Pros

 Ceramics, owing to their brittleness, have either covalent or ionic bonds. One advantage is that such bonds are stronger than the metallic bonds.

Cons

 The challenge though, is that ceramics possess significantly elevated chances of failure occurrence and are therefore, susceptible to cracking before attaining the desired yield stress.

2. Electrical properties of materials

The electrical purpose of a material influences the choice of an engineering material for its electrical characteristics. An engineering material is can either be used as an electrical conductor or insulator. The implication is that a given material can be classified as a superconductor or a semiconductor. The conductivity of an engineering material determines its ability to allow for the flow of electric charges (Tomkins, & Wareing, 2013).  

1. The dielectric properties of materials

One of the electrical properties of an engineering material is termed as its dielectric strength. A dielectric engineering material has the capacity of storing energy if an external electric field flows across it. There can be abrupt excitation of significant quantity of electrons to the energies found within the specified conduction bandwidth when enormously elevated electric field flows through a dielectric material (William, Smith & Hashemi, 2011). As a result, there can be significant rise in the motion of the electrons that can lead to focalized vaporization, combustion and melting that overwhelmingly degrades the engineering material or makes it to fail (Soibam, & Sanatombi, 2014). The occurrence called dielectric strength or sometimes known to as dielectric breakdown is experienced.

Capacitance

In a capacitor, a unit plate of a capacitor acquires positive charges in the event that a voltage V flows through it while another one acquires negative charges. The resultant electric field moves from the positive to the negative respectively.  To facilitate the computation of the capacitance C, an expression that is commonly employed is C=Q/V where Q = the quantity of charged stored on either plates of the capacitor and V in the applied voltage flowing through the capacitor. Its units are in coulombs per volt (Farads), F.

Electricity Transmission: cables such as copper and aluminum wire are widely used for power transmission.

Storage of charge: capacitors are used in electronic appliances to store electric charges.

Insulation: poor electrical conductors such as rubber and plastic are used as insulators, for example, as handles of appliances.

Current regulation: materials with high resistance such as metal oxides are widely used to control the amount of current flowing in electrical appliances.

Pros

Malleability: electrical materials such as aluminum are highly malleable and can be forged into different shapes

Ductility: electrical materials such as copper can be drawn into wires of different dimensions.

Cons

High costs: copper cables are quite expensive and therefore, require high initial cost of investment.

Heavy: electrical materials such as copper are heavy and are therefore, difficult to transport from one point to another compared to optical materials such as optical fiber.

Corrosion: electrical materials such as aluminum are susceptible to corrosion and therefore, require constant replacement.

Optical property of an engineering material is associated with its interaction with electromagnetic radiation. Such radiation may have properties that fall within or outside the visible light spectrum (Tilleman, 2010). Signal transmission via a metallic cable conductor is electronic, while in fibers it is via photons. This aids in faster transmission at great densities to longer distances with decreased error rate. One of the greatest examples of optical engineering materials is optical fiber that forms the backbone of the communication systems today. The coaxial cable transmits the signals, whereas the cladding constricts the light beam to the coaxial cable. The outer outer coating guards the coaxial cable and cladding from the peripheral environment. Optical fiber employs the theorem of total internal reflectance. Characteristically, both the coaxial cable and cladding are manufactured using out of the ordinary types of glass with circumspectly regulated indices of refraction.

Telecommunication: there are many uses of optical fibers in telecommunication such as universal networks to desktop computers for the broadcast of data, voice, or video over a given distance. For example, old telephone service (POTS) and Local exchange carriers (LECs) (Tilley, 2010).

Data transmission: Multinational companies require secure, trustworthy mechanisms to convey data and financial data between premises to the desktop computers or terminals and to transmit data across the globe (Callister, & Rethwisch, 2007).

Transportation systems: fiber-optic-oriented telemetry mechanisms is employed in intelligent transportation mechanisms like smart highways coupled with intelligent traffic lights, automatic tollbooths, and convertible message signs.

Biomedical industry: Fiber-optic schemes are applied in the majortiy of contemporary telemedicine dagdets for transmiting digital diagnostic images. The additional uses include space, military, motorvehicle, and the manufacturing sector.

Pros

Size and weight: the optical fibers are light in weight with small coaxial diameter. This helps during the rolling out process over long distances.

Signal reliability: there is minimal electromagnetic interference in the case of optical signals thus; they can travel over comparatively longer distances.

Bandwidth capacity: a lot of information can be carried out by the optical signals compared to the electrical ones.

Cons

Switching: there is poor traffic switching even though there is increased data transmission efficiency in the case of point-to-point transmission.

Physical constraints: the coaxial cables cannot withstand extreme bending and are susceptible to losing some light transmission characteristics.

Cost per user: the cost of deploying optical fibers to homes and points of consumption is comparatively higher.

Different engineering materials have different thermal properties since they react differently when exposed to different degrees of temperature. For example, aluminum oxide occurs due to high quantities of negative energy and this renders it a desirable refractory engineering material that possesses suitable chemical stability. Such a fact explains its occurrence in high temperate regions. The thermal conductivity of aluminum oxide (determined in W/mK) is its ability to conduct heat (Chawla, 2012).  This characteristic of aluminum oxide explains the level at which transmission of thermal energy occurs through it. Due to its relatively elevated thermal conductivity, the oxide has a broad range of applications since it is a high temperature engineering material in the modern world of engineering. The thermal expansion coefficient of this oxide is relatively low and this enables it to be applied in many systems that involve high temperatures (Callister, & Rethwisch, 2012). The engineering materials that possess microstructures and great thermal expansion coefficient are prone to temperature-induced failures of systems. This condition occurs as a result of the microstructure’s random orientation that makes it to expand  and contract by differing quantities in many directions.

Insulation: materials that possess bad thermal properties such as cork, rubber are widely used as handles of heating and electrical appliances such as electric kettles.

Heating: materials with good thermal properties such as aluminum are widely used for heating, cooking, and other heat-related applications such the manufacture of soldering bits.

Cons

Materials with poor thermal conductivity lead to high power consumption when put under uses that require heating such as cooking. 

Pros

Good thermal conductors have versatile range of applications such as the manufacture of electrical and heating appliances like iron boxes, cookers, and electric coils.

Small quantities of alloying elements are frequently added to metals to improve some specific properties of the metals.  Alloying can improve or lower the strength, corrosion resistance, hardness, electrical and thermal conductivity, or alter the color of a given engineering metal.  The introduction of an element to improve one characteristic may have unwanted effects on other characteristics. 

Strength

Copper metal often undergoes a common procedure called solid solution strengthening.  Little amounts of an alloying element introduced to molten copper will entirely dissolve and result to a single phase of homogeneous microstructure.  Sometimes, additional quantities of the alloying substance will not dissolve. Therefore, the exact quantity relies on the solid solubility of the specific element in copper metal.  When that particular solid solubility limit is surpassed, two distinct microstructures result, with varying compositions and hardness (Luque, & Hegedus, 2011).  A non-alloyed copper is comparatively in regard to common structural metals.  A metal alloy with tin mixed with copper is called bronze.  The resultant alloy is stronger and harder compared to either of the two unalloyed metals.  The same applies to zinc alloyed with copper to result to brass.  

The most effective method of improving the electrical and thermal conductivity of copper is to reduce the impurity levels.  The presence of impurities and other common alloying components will lessen the electrical and thermal conductivity of copper, except for silver.  As the quantity of the alloying element rises, the electrical conductivity of the alloy declines (Provatas, & Elder, 2011).  On the other hand, Cadmium has the nominal effect on resulting alloy's electrical conductivity. Others include zinc, tin, nickel, aluminum, silicon, manganese, and phosphorus. 

Color

Unalloyed copper possesses a reddish-gold color that rapidly oxides to dull green.  Given that copper has natural impurities or can undergo alloying with over one additive, it is difficult to establish the particular effect each alloying substance has on the color of the resulting alloy.  For instance, electrolytic tough pitch copper has traces of silver, iron, and sulfur and possesses a soft pink color (Kalpakjian, & Schmid, 2014).  In addition, gilding copper has a reddish-brown color and has traces of zinc, iron, and lead. 

Oxidation: Silicon can be used in place of phosphorus to deoxidate copper when conductivity is of critical concern. Phosphorus is mostly used to deoxidize copper in order to improve its hardness and strength, but critically interferes with its conductivity (Rudin, & Choi, 2012). 

Ornamental applications: Brass alloy is commonly employed for ornamental purposes owing to its similarity with gold in terms of appearance. 

Pros

The figure below summarizes the application and importance of alloying metals with different metal traces.

Cons

Reduced properties: Unalloyed copper is a good conductor of electrical current and heat compared to the alloyed type. Even though various mechanisms are engraved in thermal conductivity, the introduction of rising amounts of elements or impurities also leads to a decline in thermal conductivity (Park, 2012).  For instance, Zinc causes an insignificant effect on the thermal conductivity of copper. 

In conclusion, engineering materials are vital in everyday life owing to their flexible structural characteristics. Other than their features, they do play a significant role in the manufacturing industry such as die-casting, forging, annealing, and ordinary casting due to their physical characteristics. The primary physical characteristics of the commonly utilized engineering materials include electrical, thermal, magnetic, and optical properties.

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