Material Science and Engineering
Table of Contents
- 1 Material Science and Engineering
- 1.1 Structure
- 1.2 Why Study Materials Science and Engineering?
- 1.3 Classification of Materials
As we see in the history, so materials are profound seated in our culture. If we talk about the applications of the materials then we find that the application of material science is everywhere for example-Transportation, housing, clothing, communication, recreation, and food production etc.
Material Science and Engineering can be easily understanble if we subdivide the title into two segments which is material science and materials engineering subdisciplines.
In Materials science and Engineering, we study about “the relationships that exist between the structures and properties of materials“.
In Materials engineering, we study on the basis of these structure–property correlations that how “the designing or engineering of the structure of a material is done to produce a predetermined set of properties“.
In this regard of Material Science and Engineering, the role of material scientist and material engineer is to develop or synthesize new materials and to create new products or systems using existing materials and/ or to develop techniques for processing materials respectively.
Important components of the subject Materials Science are structure, properties, processing, and performance. A schematic interrelation between these four components is shown in figure below.
In material science, mainly we talk about the structure of a material and how the material properties are related to its structure.
So here, it becomes very important to understand the structure of a material. So in the view of understanding the structure of the material, first we will discuss about the structure.
In simple language we can say that the structure of material is the arrangement of internal components material.
Subatomic structure involves electrons within the individual atoms and interactions with their nuclei.
On an atomic level, structure encompasses the organization of atoms or molecules relative to one another.
These are the structure of the material which can be seen by the naked eye.
These are the structure of the material which can not be seen by the naked eye. To see the micro structure of any of the material, we use an instrument called Microscope.
There are various types of microscopes available for example: Optical MIcroscope (OM), Scanning Electron Microscope (SEM), and Telescope Electron MIcroscope (TEM).
Crystal sturcture can be defined as the arranagements of the atoms in solids.
Why Study Materials Science and Engineering?
All engineers need to know about materials. Even the most “immaterial”, like software or system engineering depend on the development of new materials, which in turn alter the economics, like software-hardware trade-offs. Increasing applications of system engineering are in materials manufacturing (industrial engineering) and complex environmental systems.
Innovation in engineering often means the clever use of a new material for a specific application. For example: plastic containers in place of age-old metallic containers. It is well learnt lesion that engineering disasters are frequently caused by the misuse of materials.
So it is vital that the professional engineer should know how to select materials which best fit the demands of the design – economic and aesthetic demands, as well as demands of strength and durability.
Beforehand the designer must understand the properties of materials, and their limitations. Thus it is very important that every engineer must study and understand the concepts of Materials Science and Engineering.
This enables the engineer
- To select a material for a given use based on considerations of cost and performance.
- To understand the limits of materials and the change of their properties with use.
- To be able to create a new material that will have some desirable properties.
- To be able to use the material for different application.
Classification of Materials
Solid materials have been conveniently grouped into three basic categories: metals, ceramics, and polymers. This scheme is based primarily on chemical makeup and atomic structure, and most materials fall into one distinct grouping or another.
In addition, there are the composites, which are engineered combinations of two or more different materials. A brief explanation of these material classifications and representative characteristics is offered next.
Another category is advanced materials—those used in high-technology applications, such as semiconductors, biomaterials, smart materials, and nano-engineered materials.
Ferrous materials are produced in larger quantities than any other metallic material. Three factors account for it:
(a) Availability of abundant raw materials combined with economical extraction,
(b) Ease of forming and
(c) Their versatile mechanical and physical properties.
One main drawback of ferrous alloys is their environmental degradation i.e. poor corrosion resistance. Other disadvantages include: relatively high density and comparatively low electrical and thermal conductivities.
In ferrous materials the main alloying element is carbon (C). Depending on the amount of carbon present, these alloys will have different properties, especially when the carbon content is either less/higher than 2.14%.
This amount of carbon is specific as below this amount of carbon, material undergoes eutectoid transformation, while above that limit ferrous materials undergo eutectic transformation.
Thus the ferrous alloys with less than 2.14% C are termed as steels, and the ferrous alloys with higher than 2.14% C are termed as cast irons.
Materials in this group are composed of one or more metallic elements (e.g., iron, aluminum, copper, titanium, gold, and nickel), and often also nonmetallic elements (e.g., carbon, nitrogen, and oxygen) in relatively small amounts.
Atoms in metals and their alloys are arranged in a very orderly manner and in comparison to the ceramics and polymers, are relatively dense.
With regard to mechanical characteristics, these materials are relatively stiff and strong, yet are ductile (i.e., capable of large amounts of deformation without fracture), and are resistant to fracture, which accounts for their widespread use in structural applications.
Ceramics are compounds between metallic and nonmetallic elements; they are most frequently oxides, nitrides, and carbides. For example, common ceramic materials include aluminum oxide (or alumina, Al2O3), silicon dioxide (or silica, SiO2), silicon carbide (SiC), silicon nitride (Si3N4), and, in addition, what some refer to as the traditional ceramics—those composed of clay minerals (i.e., porcelain), as well as cement and glass.
With regard to mechanical behavior, ceramic materials are relatively stiff and strong—stiffnesses and strengths are comparable to those of the metals. In addition, they are typically very hard.
Historically, ceramics have exhibited extreme brittleness (lack of ductility) and are highly susceptible to fracture.
Ceramic materials are typically insulative to the passage of heat and electricity (i.e., have low electrical conductivities), and are more resistant to high temperatures and harsh environments than metals and polymers.
With regard to optical characteristics, ceramics may be transparent, translucent, or opaque, and some of the oxide ceramics (e.g., Fe3O4) exhibit magnetic behavior.
Plastic and rubber are the two most common materials which come in the category of Polymers. Many of them are organic compounds that are chemically based on carbon, hydrogen, and other nonmetallic elements (i.e., O, N, and Si).
Some of the common and familiar polymers are polyethylene (PE), nylon, poly(vinyl chloride) (PVC), polycarbonate (PC), polystyrene (PS), and silicone rubber.
These materials typically have low densities, whereas their mechanical characteristics are generally dissimilar to the metallic and ceramic materials—they are not as stiff nor as strong as these other material types.
A composite is composed of two (or more) individual materials, which come from the categories as discussed before—metals, ceramics, and polymers.
The design goal of a composite is to achieve a combination of properties that is not displayed by any single material, and also to incorporate the best characteristics of each of the component materials.
Some naturally occurring materials are composites—for example, wood and bone.
Now, most of the composite materials are synthetic (or human-made) composites, which are being developed to fulfill the special purposes.
One of the most common and familiar composites is fiberglass, in which small glass fibers are embedded within a polymeric material (normally an epoxy or polyester).
The glass fibers are relatively strong and stiff (but also brittle), whereas the polymer is more flexible. Thus, fiberglass is relatively stiff, strong, and flexible.
Another technologically important material is the carbon fiber–reinforced polymer (CFRP) composite—carbon fibers that are embedded within a polymer.
These materials are stiffer and stronger than glass fiber–reinforced materials, but more expensive.
Applications-aircraft, aerospace, bicycles, golf clubs, tennis rackets, and skis/snowboards, and recently in automobile bumpers.
Materials that are utilized in high-technology (or high-tech) applications are sometimes termed advanced materials.
Types of advanced materials
- Semi conductors
- Bio materials
- Smart materials
- Nano materials