Fundamentals of Material Science Flashcards
What is a material?
A solid substance used in the manufacture of a technical product.
What are some things that are not included in the category of materials?
Coolants, operating fluids, soldering agents, technical gases, paints, anti-corrosion
What are some of the things material science is responsible for?
Manufacturing, Materials Applications, Characterization and Testing, Materials Production, Standards and Nomenclature.
What are some aspects of material selection.
- Suitable for Loads
- Functionality
- Manufacturing,
- Environmentally
Compatible - Cost Appropriate
- Certification
What is a process and a process chain?
A process is a step to create or modify a material.
A process chain is several processes in a row.
What are the three high level classifications of materials?
- Metals and Alloys
- Plastics
- Ceramics and Glass
What are the four main categories of material properties?
- Physical Properties
- Mechanical Properties
- Chemical Properties
- Processing Properties
Give examples of physical properties (7)
- Density
- Thermal Expansion
- Magnetic Properties
- Thermal Conductivity
- Electrical Properties
- Thermal Capacity
- Optical and
Electromagnetic
Give examples of chemical properties (4)
- Corrosion
- Resistance to other
substances - Flammability
- Hydrogen Embrittlement
Give examples of mechanical properties (6)
- Strength
- Toughness and Ductility
- Wear and Fatigue
Behavior - Stiffness
- Hardness
- Tribology and Friction
Values
Give examples of processing properties (6)
- Castability
- Weldability
- Formability
- Viscosity
- Chipability
- Permeability
What are some advantages (7) and disadvantages (4) of metals and alloys?
Advantages:
- High Toughness
- High Stiffness
- High Strength
- Good Wear Resistance
- Good Conductivity
- Easy for Design
- Versatile Processability
Disadvantages:
- High Density
- Sensitive to Corrosion
- Sensitive to Chemical
Exposure
- Low Damping and Shock
Absorption
What are some advantages (6) and disadvantages (6) of plastics?
Advantages:
- Low Density
- Flexible
- Corrosion Resistant
- Electrically Insulating
- High Design Freedom
- Capable for Mass
Production
Disadvantages:
- Low Strength
- Low Stiffness
- Sensitive to Temperature
- Flammable
- Low Thermal
Conductivity
- High Thermal Expansion
What are some advantages (7) and disadvantages (3) of Ceramics and Glass?
Advantages:
- High Wear Resistance
- Low Thermal Expansion
- Heat Resistant
- Corrosion Resistant
- Electrically Insulating
- High Design Freedom
- Good Tribological
Properties
Disadvantages:
- Low Toughness
- Hard to Process
- Challenging to Design
What is the atomic number?
The number of protons in the nucleus of an atom.
What is atomic weight?
Ratio of average mass of atom w.r.t 1/12 of Carbon-12 atom.
What are the Bohr and Wave-Mechanical Atom Models?
The Bohr model represents atoms as a nucleus with electrons in simple orbit.
The wave-mechanical model represents the electrons as having energy levels, and orbitals.
What is the principal quantum number?
The shell number.
What are the shell designations? How many electrons does each have?
K(2), L(8), M(18), N(32)
Name all the subshells and the number of electrons per subshell.
s(2), p(6), d(10), f(14)
What is electronegativity?
The attraction of the atomic nucleus to an additional electron.
What is the trend of electronegativity in the periodic table?
Increases from left to right and from bottom to top. Florine has the highest electronegativity.
What are 4 important types of bonds?
- Ionic
- Covalent
- Metallic
- Van der Walls
What is the sphere spring model?
A model that idealizes atoms as having a spring between them.
How can you find potential using the sphere-spring model?
Take the integral of the net force curve w.r.t distance. Integral is taken from infinity to r.
What are the effects of maximum potential on melting temperature and bonding energy?
Both are larger if potential is larger.
What is the Formula for Elastic Modulus?
Stress = E Strain
What is Ionic Bonding?
Atom of high electronegativity steals electron from atom of low electronegativity (difference > 18)
What are crystalline structures and what are some of their properties(2)?
They are regular lattice structures.
- Hard and Brittle
- Thermally and
Electrically Insulative
What is covalent bonding?
Two atoms share atleast one valence electron to assume stable electronic configuration. The atoms must be of similar electronegativity (difference < 1.7)
What is metallic bonding?
Valance electron shared in electron clout with positive cores forming a lattice structure.
What are some properties of metallic bonds?(5)
- Good Electrical
Conductivity - High Thermal
Conductivity - Ductility
- High Reactivity
- Weaker than
covenant/ionic
What are Van der Waals Bonds
Bonds formed between polar atoms due to dipoles.
What are the two main types of testing and what are their uses?
Destructive Testing:
- Characterization of
Properties
- Validation of Component
Parameters
Non-Destructive Testing:
- Quality Assurance for
Production
- Inspection in Operation
Name 3 destructive and non-destructive tests.
Destructive:
- Tension/Compression/Bedin testing
- Hardness Testing
- Creep/Fatigue Testing
Non-Destructive:
- Ultrasonic Inspection
- X-Ray
- Acoustic Emission
What are the types of loads for material characterization? (5)
- Tension
- Compression
- Shear
- Torsion
- Bending
What are somethings that standards for testing set out? (5)
- Description of Method
- Testing machine and
measurement devices - Geometry and number of
specimens - Experimental execution
- Evaluation of results and
reporting
What are the basic elements for tensile testing? (6)
- Electro-mechanical test frame with moveable traverse and gauge
- Material specimen
- Gripper
- Mechanical extensometer for measuring l
- Load cell to determine F
- Data acquisition tool
What are the three tools that can be used to measure displacement for tensile testing?
- Strain gauge
- Mechanical Extensometer
- Optical Extensometer
What are the two main areas of a stress-strain curve?
- Elastic area
- Plastic area
What is Yield strength, Ultimate tensile strength and breaking strength in stress-strain curve?
Yield strength:
End of elastic region
Ultimate tensile strength:
Maximum stress
Breaking strength:
Strain close to breaking
How does temperature influence stress-strain curve?
It brings down ultimate tensile strength and reduces brittleness.
What are some standard hardness tests?
- Brinell
- Vickers
- Rockwell
- Knoop
- Shore
What is hardness?
Resistance of a substance to penetration by another substance.
What is the indenter used in each hardness test? (4)
Brinell – Sphere
Vickers - Diamond Pyramid
Knoop – Diamond Pyramid
Rockwell – Diamond cone
What is formula for hardness number in Brinell?
HB = 2P/[PiD(D-sqr(D^2-d^2))]
What is formula for hardness number in Vickers?
1.854P/d^2
What is formula for hardness number in Knoop?
14.2P/l^2
What is the formula for HBW?
0.102 HB
What are some advantages (1) and disadvantages (2) of Brinell testing?
Advantages
- Determination of a medium hardness in heterogeneous material
Disadvantages:
- Not applicable to thin material later
- Cant be used for very hard materials (test load too large)
What is the format for showing results of Brinell test?
Brinell Hardness HBW Indenter diameter / Test Load / Exposure Time
What are the advantages of Vickers hardness testing? (3)
Strengths:
- Applicable to wide range of materials
- Can be used for thin plates
- More precise compared to Brinell
What is the format for showing test results of Vickers Hardness test?
Vickers Hardness HV Test load / Exposure time
What are advantages (1) and disadvantages (3) of Rockwell Hardness testing?
Strengths:
- Quick and Automatable
Weaknesses:
- Small indenter
- Bad for high hardness
- Various scales
What is creep?
Time dependent deformation under constant stress and elevated temperature.
What are the three main regions in a creep graph?
Primary creep, Secondary creep, Tertiary creep
What happens in an impact bending test?
A standardized specimen is stricken with a pendulum and a hammer.
What is the notched and unnotched bending test used for?
Notched for metals
Unnotched for plastics
How does notched impact energy vary with temperature?
Increases with temperature.
