Untitled Quiz

Magnetism

• Magnetism is a phenomenon by which materials exert an attractive or repulsive force or influence on other materials.
• A magnetic field is a region surrounding a magnetic body.
• Two important ways in which electrons contribute to magnetism:
  • Orbital Magnetism
  • Spin Magnetism

Types of Magnetism

• Diamagnetism: a very weak form of magnetism that is nonpermanent and persists only while an external field is being applied.
• Paramagnetic materials: have a small, positive susceptibility to magnetic fields.
• Ferromagnetic materials: have a large, positive susceptibility to an external magnetic field.
• Antiferromagnetism: the alignment of the spin moments of neighboring atoms or ions in exactly opposite directions.
• Ferrimagnetism: exhibits a permanent magnetization.

Optical Property

• Optical property describes a material's behavior when electromagnetic radiation (light) is incident on the material's surface.
• Electromagnetic radiation refers to wave-like, electric, and magnetic components.
• Types of optical properties of materials:
  • Reflectivity: the optical property of a material when a light wave is incident on the polished surface of the material.
  • Absorption: when a beam of light is incident on the surface of the material, some part of the incident beam is absorbed by the material.

Properties of Materials

• Magnetic Property: magnetic field, magnetic moment, magnetic permeability
• Optical Property: refraction index, reflectivity
• Deteriorative Property: relates to the chemical reactivity of materials.

Processing

• Different ways for shaping materials into useful components or changing their properties.

Performance

• Function of a material's properties.

Materials Selection Process

• Determine required properties.
• Identify candidate materials.
• Identify required processing.

Atomic Structure

• Atom: nucleus (protons + neutrons) + electron
• Electrons (-) and Protons (+) have the same charge = 1.6 ×10−19 c
• Neutrons are electrically neutral.
• Protons and Neutrons have the same mass = 1.67 ×10−27 kg
• Mass of electron = 9.11 ×10−31 kg
• Atomic mass = mass of protons + mass of neutrons
• Mass no. = no. protons + no. neutrons
• Protons = atomic no.

Nuclide

• An atomic species characterized by the specific constitution of its nucleus.

Isotopes

• Atoms of the same element with different mass.

Types of Chemical Bond

• Ionic Bond: formed by the transfer of electrons between atoms.
• Covalent Bond: sharing of electrons between atoms or elements.
• Types of covalent bonds:
  • Single Covalent Bond
  • Double Covalent Bond
  • Triple Covalent Bond
• Non-Polar Covalent Bonds: electron pairs are usually shared between atoms and not pulled unequally between atoms.

Chemical Property

• A property of a substance that is observed when a substance undergoes a chemical change.
• Chemical change is a type of change that also changes the identity of a substance due to the breakage and formation of new chemical bonds.
• Examples:
  • Ability to burn
  • Ability to tarnish
  • Ability to rust
  • Ability to decompose
  • Ability to react with other chemicals
  • Instability
  • Ability to do/base reaction

Thermal Property

• Thermal characteristics relate to a material-dependent response when heat is applied to a solid body, a liquid, or a gas.
• Temperature is a degree of measuring hotness and coolness.
• Heat is the energy that is transported over a system's boundary to modify the differential between the system and its surroundings.
• Thermal properties:
  • Specific heat
  • Heat capacity
  • Thermal conductivity
  • Melting point
  • Thermal diffusivity
  • Thermal shock resistance
  • Thermal expansion

Electrical Properties

• Determine if, and how, electricity will flow through a material.
• Conductivity of Conductors, Semi-Conductors, and Insulators:
  • Insulator: a material that does not conduct electrical current.
  • Conductor: a material that easily conducts electrical current.
  • Semiconductor: a material that is between conductors and insulators in its ability to conduct electrical current.