Materials Science: Properties and Applications

Posted on Apr 30, 2024 in Chemistry

INTRODUCTION TO MATERIALS SCIENCE

Definition of materials:

When the term is used in the plural material, ie material is being referred generally to all elements that are needed for specific activities or tasks. The notion of materials can be applied to different situations and places, but always turn around several elements that are important and useful to perform some action, as well as objects which are also to be used jointly.

RAW MATERIAL:

All items included in the development of a product. The raw material is any item that is processed and incorporated in a final product.

PRODUCT:

Something occurred or is the result of work or effort. Result of a natural, social, industrial, etc.

General classification of materials

1.-Metal

It features a good electrical and thermal conductivity, high strength, stiffness, ductility. They are particularly useful in structural applications or load. The * alloys (combinations of metals) attach any property particularly desirable in a greater proportion or allow a better combination of properties.

A) ferrous materials:

Ferrum comes from the word the Romans used for iron or steel. Therefore, ferrous materials are those containing iron as its main ingredient, that is, the many qualities of iron and steel.

B) non-ferrous materials:

do not contain iron. These include aluminum, magnesium, zinc, copper, lead and other metallic elements. Alloys brass and bronze, are a combination of some of these precious metals and are called nonferrous alloys.

2.-Ceramic

They have low electrical and thermal conductivity and are often used as insulators. They are strong and hard, but fragile and brittle. New techniques to manage processes that are sufficiently resistant ceramics to fracture so they can be used in loading applications. Within this group of materials include: brick, glass, porcelain, refractories and abrasives.

3.-polymers

They are large molecular structures created from organic molecules. Have low electrical and thermal conductivity, low resistance and should be avoided warm temperatures. Thermoplastic polymers, in which the molecular chains are not rigidly connected, have good ductility and formability, in contrast, are more resistant thermosets, although strongly linked molecular chains make them more fragile. They have multiple applications including electronic devices.

4.-Semiconductors

The electrical conductivity can be controlled for use in electronic devices. They are very fragile.

5.-Composite Materials

As its name implies, are formed from two or more materials of different groups, resulting in properties not found in any of the materials individually. Long fiber reinforced thermoplastics. For example. Thermoplastic glass fabrics. Thermoformed or thermoset compounds, Cermet (ceramic and metal), metal-intermetallic laminate, hard metal (carbide metal matrix) etc.

6 .- natural raw materials:

These are obtained directly from nature and have been used since ancient times by man.

Establish a range of uses and cases related to vehicles

PHYSICO-CHEMICAL PROPERTIES OF MATERIALS

In general, the properties are separated for their study into four main branches: physical, chemical, mechanical and technological properties.

1.-MECHANICAL PROPERTIES

The behavior of materials is defined by its structure. Microscopic level, the electronic structure of an atom determines the nature of atomic bonds which in turn helps set the properties of a given material. Describe how the material supports applied forces, forces including tension, compression, impact, cyclic fatigue, or forces at high temperatures.

Tenacity:

The property of certain materials to withstand, without deforming or breaking sudden efforts that apply to them.

Elasticity:

It consists in the ability of some materials to recover their shape and size of primitive when it ceases the effort that had given deformation.

Hardness:

The resistance a material opposes the penetration.

Fragility:

A material is brittle when broken easily by the action of a shock.

Plasticity:

Ability of some solid material to acquire permanent deformation under the action of an external force or pressure without rupture.

Ductility:

Considered a variant of plasticity, is the property of certain metals have to stretch as fine wires.Malleability: Another variation of plasticity, is the possibility of transforming some thin sheet metal.

Creep:

Properties of some metals to deform slowly and spontaneously under the action of its own weight or very small loads

Fatigue:

This property is used to measure materials to be subjected to periodic load action.

Mechanical stress

By building a structure is needed as both appropriate design elements that are capable of withstanding the forces, loads and actions which will be submitted. The types of efforts that must withstand the various elements of the structures are:

The compression loads are forces trying to compress an object to tie it or make it shorter

The bending loads are forces trying to bend an object while holding both ends by a

The tension or pulling loads are forces trying to pull something apart.

Cutting loads are opposing forces that try to push an object in opposite directions simultaneously.

The torsional loads are forces trying to rotate an object in opposite directions

Buckling loads are forces that generate a phenomenon of elastic instability can occur in tablets elements slender and is manifested by the appearance of significant transverse displacement (deflection) to the main direction of compression.

The above mechanical properties generate mechanical forces which are measured accurately by mechanical tests:
Tensile test: Provides a rough idea of the tenacity and elasticity of a material.
Hardness Testing: allows to know the hardness of the material.
Shock Test: The practice allows us to know the fragility and tenacity of a material.
Technological tests: They show the characteristics of plasticity that has a material to carry out his forge, bending, stamping, etc.

2.-Mechanical testing TECHNOLOGICAL

TECHNOLOGICAL PROPERTIES

Determines the ability of a metal to be formed into pieces or parts useful or usable

Formability:

Property of metal that measures its malleability.

Fluidity:

The ability of a molten metal to produce castings complete and without blemish for a metal it must have great fluides et al.

Solderability:

The attitude of a weld metal with another identical under pressure on both hot.

Hardenability:

The property of a metal to undergo transformations in the crystalline product of successive heating and cooling and abrupt.

Forging:

Shaping a metal, beating him with hammers with which it is stretched or compressed to give the shape you want. They have this property steels low carbon

Machinability:

Property metal machine left by an appropriate cutting tool material presented in this material.

3.-PHYSICAL PROPERTIES OF MATERIALS

Physical properties are those that remain original properties of the substance and its molecules are not modified. And so are their own and the material characteristics and intrinsic

A) ELECTRICAL

PROPERTIES:

describe the electrical behavior of the metal, which is often more critical than its mechanical behavior. There is also the dielectric behavior, characteristic of the materials that impede the flow of electrical current, which goes beyond simply providing isolation. Name a few.

• DRIVERS: Those with a large number of electrons in the conduction band, ie with great ability to conduct electricity (high conductivity). All metals are conductors, some better than others.

• SEMICONDUCTORS: some materials are conductors, but the electrons can easily jump from the valence band to the conduction, if external power is communicated to them. Examples include silicon, germanium, gallium arsenide, mainly ceramics.

• O DIELECTRIC INSULATORS: Those whose electrons are tightly bound to the nucleus and therefore are unable to move through the interior and, consequently, lead. Good insulators are eg mica, porcelain, polyester, in integrating a large number of ceramic materials and polymer materials.

• CONDUCTIVITY Electrical conductivity is the ability of a medium or physical space to allow the passage of electric current through it. It is also defined as the natural property characteristic of each body that represents the ease with which electrons can pass through it.

B) MAGNETIC PROPERTIES:

It is a physical phenomenon wherebymaterials exert forces of attraction or repulsion on other materials. There are some known materials that have submitted easily detectable magnetic properties such as nickel , iron , cobalt and its alloys are commonly called magnets . However, all materials are influenced, more or less so, by the presence of a magnetic field

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Magnetic Materials

C) Thermal Properties: Determine the behavior of the materials from heat

• • Thermal conductivity is the property of the material to transmit heat, producing naturally a feeling of cold to the touch. A material can be good or bad heat conductor.
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    Fusibility:

    ease with which a material can melt.

• • Solderability:

    
    ease of a material to be welded to itself or another material. Logically good fusibility materials typically have good weldability.

• • Thermal conductivity:

    
    Ability of material to conduct heat.

• • Heat of fusion:

    
    additional heat is needed initially cause the material begins to melt.

• • Thermal Expansion:

    
    Trend of the material to increase its size when the temperature rises.

• • Melting point:

    
    temperature necessary to change from solid to liquid.

Here we have other physical properties

Specific heat:

Quantity of heat required to raise one degree temperature of a specific amount of material.

Density:

relatively compact conformation of the material. Density is the mass of material by the volume it occupies.

Weight:

Quantity of gravity of an object resulting from the gravitational pull of the Earth.

Freezing Point:

Temperature required to change from liquid to solid.

4-.PROPIEDADES CHEMICAL

A chemical property is any property of a material that becomes evident during a chemical reaction , that is, any quality that can be established only by changing the chemical identity of a substance. In other words, the chemical properties can not be determined simply by looking or touching the substance, the internal structure must be concerned for their chemical properties are investigated.

Oxidation is the chemical reaction from which an atom, ion or molecule gives electrons are then said to increase its oxidation state. While this explanation is sufficient in practical terms is not entirely correct because, although the transfer of electrons will cause a change in the oxidation state, you can also make this change to occur without electron transfer.

A chemical reaction or chemical change is all chemical process where two or more substances (called reactants), the effect of an energy factor, are transformed into other substances called products. These substances may be elements or compounds . An example of chemical reaction is the formation of iron oxide produced by reacting the oxygen of the air with the iron .

Corrosion: is defined as the deterioration of a material as a result of electrochemical attack by their environment. More generally, can be understood as the general trend with the materials to find your way more or less stable internal energy. Whenever corrosion is caused by an electrochemical reaction (oxidation), the speed at which it takes place will depend to some extent on the temperature, salinity of the fluid in contact with the metal and the properties of the metals in question. Other non-metallic materials also corrode through other mechanisms.

Corrosion may be through a chemical reaction (redox) in which three factors:

• The piece manufactured
• The environment
• Water

As we have concluded this phenomenon of corrosion is produced naturally by the tendency of metals to transfer electrons, according to potential of cell. However, this process can result in an unnatural way by a torch which applies heat to the metal, forcing him to oxidize.

* Alloys: solid combination of metals or mixtures of two or more metals, where atoms of one metal occupy little spaces between the atoms of another metal.