Microstructure is the small scale structure of a material, defined as the structure of a prepared surface of material as revealed by a microscope above 25× magnification. The microstructure of a material (such as metals, polymers, ceramics or composites) can strongly influence physical properties such as strength, toughness, ductility, hardness, corrosion resistance, high/low temperature behaviour or wear resistance. These properties in turn govern the application of these materials in industrial practice. Microstructure at scales smaller than can be viewed with optical microscopes is often called nanostructure, while the structure in which individual atoms are arranged is known as crystal structure. The nanostructure of biological specimens is referred to as ultrastructure
Macrostructures are distinguished from societal microstructures consisting of the situated social interaction of social actors, often described in terms of agency. This distinction in sociology has given rise to the well-known macro-micro debate, in which micro sociologists claim the primacy of interaction as the constituents of societal structures, and macro sociologists the primacy of given social structure as a general constraint on interaction.
a solid material which is typically hard, shiny, malleable, fusible, and ductile, with good electrical and thermal conductivity (e.g. iron, gold, silver, and aluminium, and alloys such as steel).
Characteristics of metals are as follow
Conductor of heat and electricity
With one exception, all are solid at room temperature
Valence electrons are held loosely
Tend to lose electrons
A polymer is a large molecule, or macromolecule, composed of many repeated subunits. Because of their broad range of properties, both synthetic and natural polymers play an essential and ubiquitous role in everyday life.[Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. Their consequently large molecular mass relative to small molecule compounds produces unique physical properties, including toughness, viscoelasticity, and a tendency to form glasses and semi crystalline structures rather than crystals.
The microstructure of a polymer (sometimes called configuration) relates to the physical arrangement of monomer residues along the backbone of the chain. These are the elements of polymer structure that require the breaking of a covalent bond in order to change. Structure has a strong influence on the other properties of a polymer. For example, two samples of natural rubber may exhibit different durability, even though their molecules comprise the same monomers.
Characteristics of polymers are
Simple to manufacture
Microstructure, which is too small to be seen with the naked eye, plays an important factor in the final property of a material. For ceramics, the microstructure is made up of small crystals called grains. In general, the smaller the grain size, the stronger and denser is the ceramic material. In the case of a glass material, the microstructure is non-crystalline. When these two materials are combined (glass-ceramics), the glassy phase usually surrounds small crystals, bonding them together.
The wide variety of applications for ceramic materials results from their unique properties. In many respects, these properties cannot be achieved by other materials. Among the many properties that ceramic products take advantage of include:
High mechanical strength
Resistance to wear
Resistance to corrosion or chemical attack
high working temperature
low or high thermal conductivity
good electrical insulation
Dielectric and ferroelectric properties
Depending on the composition and the processing of the raw materials, as well as the fabrication and firing conditions, the properties of the material can often be closely tailored to the desired application
A composite material (also called a composition material or shortened to composite) is a material made from two or more constituent materials with significantly different physical or chemical properties that, when combined, produce a material with characteristics different from the individual components. The individual components remain separate and distinct within the finished structure. The new material may be preferred for many reasons: common examples include materials which are stronger, lighter, or less expensive when compared to traditional materials. More recently, researchers have also begun to actively include sensing, actuation, computation and communication into composites, which are known as Robotic Materials.
Typical engineered composite materials include:
Composite building materials, such as cements, concrete
Reinforced plastics, such as fibre-reinforced polymer
Ceramic composites (composite ceramic and metal matrices)
Composite materials are generally used for buildings, bridges, and structures such as boat hulls, swimming pool panels, race car bodies, shower stalls, bathtubs, storage tanks, imitation granite and cultured marble sinks and countertops. The most advanced examples perform routinely on spacecraft and aircraft in demanding environments.
Composite materials include some of the most advanced engineering materials today. The addition of high strength fibres to a polymer matrix can greatly improve mechanical properties such as ultimate tensile strength, flexural modulus, and temperature resistance
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