22 Questions
What is the focus of materials engineers in the field of materials engineering?
Transforming materials into useful devices
In the context of materials science, what does the term 'microstructure' refer to?
The microscopic changes in the structure of a material
Why was it challenging to produce long lengths of wires using ceramic superconductors?
Ceramic superconductors are brittle
Which material is commonly used in food packaging due to its ability to be easily formed into thin, flexible, and airtight films?
Polyethylene
What is the primary function of material scientists and engineers according to the text?
Determining the properties of a material based on its performance
What is the purpose of using epoxy in the encapsulation of integrated circuits?
To provide insulation and moisture resistance
What material is used in automobile engine blocks due to its strength and moisture-resistance?
Gray Cast Iron
Which material is used in transistors and integrated circuits for its castable, machinable, and vibration-damping properties?
Silicon
What material is used in optoelectronic systems for converting electrical signals to light, including lasers and laser diodes?
GaAs
Which material is commonly used in window glass or soda-lime glass due to its composition of SiO2-Na2O-CaO?
SiO2-Na2O-CaO
What material is used in aircraft components for being optically transparent and thermally insulating?
Graphite epoxy
Which material is known for its high hardness yet good shock resistance, making it suitable for use in capacitors for microelectronics?
Barium Titanate
What type of bonding is easiest to describe and visualize?
Ionic Bonding
In which crystal structure are atoms arranged in a hexagonal pattern?
Hexagonal Close-Packed (HCP)
What type of material lacks a crystalline structure and does not exhibit long-range atomic order upon solidification?
Non-crystalline Material
Which property refers to a material's ability to absorb energy when deformed elastically and recover that energy upon unloading?
Resilience
In hydrocarbons, what does it mean when all bonds are single ones and no new atoms may be joined without removing existing ones?
Saturated
Which test is conducted by applying a gradually increasing tensile load along the long axis of a specimen?
Tension Test
What describes the point at which a metal transitions from elastic behavior to plastic deformation?
Yield Strength
Which type of materials have extensive Van der Waals and hydrogen bonding between chains, resembling a mass of 'spaghetti'?
Network Polymers
'Glass Transition Temperature' refers to the range over which a polymer undergoes what transformation?
'Liquid' to 'Rigid' transition
'Viscoelastic Behavior' in materials is characterized by being intermediate between which two extremes?
'Totally Viscous' and 'Totally Elastic'
Study Notes
Forces and Bonding
- Attractive force originates from the type of bonding between two atoms
- Repulsive force arises from the interaction between negatively charged electron clouds of two atoms, important only at small values of r as outer electron shells overlap
- Net force is the sum of attractive and repulsive components
- Net curve is the sum of attractive and repulsive curves
Types of Bonding
- Ionic Bonding: found in compounds of metallic and non-metallic elements, easy to describe and visualize
- Covalent Bonding: found in materials with small differences in electronegativity
- Metallic Bonding: found in metals and their alloys
Ionic Bonding
- Sodium Chloride (NaCl) is a classic ionic metal
- Ion Cores: remaining nonvalence electrons and atomic nuclei form
Secondary Bonds
- Van der Waals (secondary bonds): weak in comparison to primary bonds, exist between virtually all atoms or molecules
- Electric Dipole: exists whenever there is a separation of positive and negative portions of an atom or molecule
- Dipole Interactions: occur between induced dipoles and polar molecules
- Hydrogen Bonding: a special type of secondary bonding, exists between some molecules with hydrogen as a constituent
- Permanent Dipole Moments: exist in some molecules due to an asymmetrical arrangement of positively and negatively charged regions
Materials Science
- Crystalline Material: atoms are situated in a repeating or periodic array over large atomic distances
- Non-crystalline/Amorphous Material: lacks crystalline structure and long-range atomic order upon solidification
- Crystal Structure: spatial arrangement of atoms, ions, or molecules within a material
- Polycrystalline Material: exhibits long-range order due to the formation of multiple small crystalline regions or grains
Crystal Structures
- Atomic Hard-Sphere Model: illustrates atoms as spheres that touch each other at their closest points, representing nearest-neighbor interactions
- Lattice: three-dimensional array of points coinciding with atom positions
- Face-centered Cubic (FCC): crystal structure found for many metals, has a unit cell of cubic geometry
- Body-centered Cubic (BCC): another common metallic crystal structure, has a cubic unit cell with atoms located at all eight corners and a single atom at the cube center
- Hexagonal Close-Packed (HCP) Structure: atoms are arranged in a hexagonal pattern with each layer directly on top of the other
Test your knowledge on the basics of Material Science and Engineering, focusing on topics such as composition, structure, synthesis, and processing of materials. Explore the interdisciplinary field concerned with inventing new materials and improving previously known ones.
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