Term 2, Material Science Flashcards
Define the term “primary bonds”.
Primary bonds are bonds in which they are strong in nature. The three types of primary bonds are Ionic bonds, Metallic bonds, and Covalent bonds. Primary bonds are much stronger than secondary bonds.
Define the term “secondary bonds”.
Secondary bonds are bonds in which there are no sharing/transfer of electrons. They form due to dipole attractions.
Define “Ionic Bonds”
An ionic bond is the attractive force existing between a positive and negative ion when they are brought close together. Ions are formed when atoms lose or gain electrons in order to character their outer shell electron configurations.
Define “Covalent Bonds”
A covalent bond is formed when pairs of electrons are shared by several atoms and have their energies lowered as a result of this. Stable covalent bonds are formed between many non-metallic elements since the atoms usually possess half-filled out electrons shells.
Define “Metallic Bonds”
The metallic bond is far more complex model than either the ionic or covalent bonds. It predominates in metals. Individual metallic atoms lose their outer valence electrons which then exist in the metal as a could or sea of electrons. The bond is the electrostatic attraction between the fixed positive ion cores of the atom and the negative electron cloud.
Define the “crystalline state”.
The vast majority of engineering materials are crystalline. Including all metals , many ceramics , some plastics, and most mineral.
What is “stress”? What equation do you use to find it? What is it measured in?
Stress is defined as any pressure or tension exerted on a material object. Stress is calculated by using Force/Area. It is measured in N/m^2 (Newtons per meters squared).
What is “strain”? What equation do you use to find it? What is it measured in?
Strain is the amount of deformation in the direction of the applied force. Strain is calculated by using Extension/Original Length (E = Δx/x) . It is not measured in units as it is a ratio.
What is the “Young Modulus”? What equation do you use to find it? What is it measured in?
Young’s modulus is a measure of the ability of a material to withstand changes in length when under lengthwise tension or compression. The Young Modulus is calculated by the equation Stress/Strain. It is measured in Pascals (Pa).
What are the three primary types of hardness tests?
The three types of hardness tests are:
- Brinell Hardness Test
- Vickers Hardness Test
- Rockwell Hardness Test
What is “tension”?
A tensile force is one which puts something in tension/tries to pull it apart.
What is “compression”?
A compressive force is one which puts something under compression/tries to squash the material.
What is the “elastic limit” of a material?
The elastic limit is defined as the greatest stress that a material can endure without taking plastic deformation.
What is the “proportional limit”?
Proportional Limit is defined as the greatest stress that a material can endure without losing straight-line proportionality between stress and strain. Most materials exhibit the proportional limit within the elastic limit. Thus for all practical purposes the proportional limit can be regarded as identical with the elastic limit, and is often known as the proportional elastic limit.
What is “Ultimate Tensile Strength” (UTS)?
The ultimate tensile strength (UTS) of a material is the maximum stress that the material is capable of developing. Once the UTS is exceeded, the load appears to drop away to failure, and the greatest amount of local “necking” occurs in ductile materials.
