Material Science

• Materials Engineering The discipline of designing or engineering the structure of a material to produce a predetermined set of properties based on established structure-property correlation.
• Materials Science - The discipline of investigating the relationships that exist between the structures and properties of materials.
• METAL - these materials are characterized by high thermal and electrical conductivity; strong yet deformable under applied mechanical loads; opaque to light (shiny if polished).
• CERAMICS - These are inorganic compounds, and usually made either of oxides, carbides, nitrides, or silicates of metals.
• POLYMERS- in the form of thermo-plastics (nylon, polyethylene,

  polyvinyl chloride, rubber, etc.) consist of molecules that have

  covalent bonding within each molecule. _______ in the form

  of thermo-sets (e.g., epoxy, phenolics, etc.) consist of a

  network of covalent bonds.
• Composite materials are multiphase materials obtained by

  artificial combination of different materials to attain properties

  that the individual components cannot attain
• ADVANCE MATERIALS

  ➢ Materials that are utilized in high-technology (or high-tech) applications are sometimes termed advanced

  materials. By high technology we mean a device or product that operates or functions using relatively

  intricate and sophisticated principles; examples include electronic equipment (camcorders, CD/DVD players,

  etc.), computers, fiber-optic systems, spacecraft, aircraft, and military rocketry.
• Semiconductors have electrical properties that are intermediate between the electrical conductors and insulators. Furthermore, the electrical characteristics of these materials

  are extremely sensitive to the presence of minute

  concentrations of impurity atoms, for which the concentrations

  may be controlled over very small spatial regions. Made possible the advent of integrated

  circuitry that has totally revolutionized the electronics and

  computer industries over the past three decades
• Biomaterials are employed in components implanted into the

  human body to replace diseased or damaged body parts.

  These materials must not produce toxic substances and must

  be compatible with body tissues (i.e., must not cause adverse

  biological reactions). All of the preceding materials—metals,

  ceramics, polymers, composites, and semiconductors—may

  be used as biomaterials.
• Smart materials are a group of new and state-of-the-art materials now being developed that will have a significant influence on many of our technologies.

  Smart materials are a group of new and state-of-the-art materials now being developed that will have a significant influence on many of our technologies. will have a significant influence on many of our technologies.

  of-the-art materials now being developed that will have asignificant influence on many of our technologies.
• NANOMATERIALS One new material class that has fascinating properties and tremendous technological promise
• Democritus believed that atoms were uniform, solid, hard,

  incompressible, and indestructible and that they moved in infinite

  numbers through empty space until stopped. Differences in atomic

  shape and size determined the various properties of matter.
• Suggested world was made of two things – empty space and

  “ATOMOS”.
• John Dalton theory states that all matter is made of atoms, which

  are indivisible. The second part of the theory says all atoms of a

  given element are identical in mass and properties. The third part

  says compounds are combinations of two or more different types of

  atoms.
• J.J. Thomson experiments with cathode ray tubes showed that all

  atoms contain tiny negatively charged subatomic particles or

  electrons. Proposed the plum pudding model of the atom,

  which had negatively-charged electrons embedded within a

  positively-charged "soup.“
• Ernest Rutherford described the atom as a tiny, dense, positively

  charged core called a nucleus, in which nearly all the mass is

  concentrated, around which the light, negative constituents, called

  electrons, circulate at some distance.
• Electrons are the smallest of the three particles that make up atoms.
• Electrons are found in shells or orbitals that surround the nucleus of an atom.
• Protons and neutrons are found in the nucleus. They group together in the center of

  the atom.
• Electrons (-) are negative charges.
• Protons (+) are positive charges.
• Neutrons (0) are a type of subatomic particle with no charge (they are neutral).
• When the chemical elements are thus arranged, there is a recurring pattern called the “Periodic Law” in their properties, in which elements in the same column (group) have similar properties.
• The initial discovery, which was made by Dmitry I. Mendeleyev in the mid-19th century, has been of inestimable value in the development of chemistry.
• The Atomic Mass is a weighted average of all of the isotopes of that element, in which the mass of each isotope is multiplied by the abundance of that particular isotope.
• Atomic Number, the number of a chemical element in the

  periodic system, whereby the elements are arranged in

  order of increasing number of protons in the nucleus.
• Atoms with the same number of protons but different numbers of

  neutrons are called isotopes.
• nuclear symbol is a type of

  shorthand notation that identifies the element

  (by symbol or atomic number) and the mass

  number of the element.
• Atom

  -electrically neutral

  -same no. of protons and electrons

  -no. OF protons defines its element
• Ion

  -electrically charge

  -diff. no. Of protons and electrons

  -may contain one or more atoms
• Cation = a positive ion
• Anion = a negative ion
• CRYSTAL is a solid where the atoms form a periodic arrangement.
• CRYSTALLINE DEFECT refers to a lattice irregularity having one

  or more of its dimensions on the order of an atomic diameter.
• When an atom is missing or an atom is in an irregular place in the lattice structure, the corresponding defects are known as Point Defects.
• Vacancies are simplest point defects in a crystal which refers to a missing atom at its site.
• An Interstitial Defect is a type of point crystallographic defect where an atom of the same or of a different type, occupies a normally unoccupied site in the crystal structure.
• When an impurity atom occupies the one of the positions of the parent atoms of the crystal, then such a

  defect is known as substitutional defect.
• These defects are special case of point defects.

  Errors in charge distribution in solids are called Electronic Defects.
• Stoichiometry is a state for ionic compounds where there is the exact ratio of cations to anions as prescribed by the chemical formula.