Material_Science_Flashcards copy

Question 1

atomic Levels of Structure

Answer 1

Atomic, Crystalline, Nanostructure, Microstructure, Macrostructure

Question 2

Bonding Principles

Answer 2

Valence electrons participate in bonding; forces exist when atoms are close together

Question 3

Bonding Energies

Answer 3

Minimum energy required for separation; larger bonding energies result in higher melting points

Question 4

Ionic Bonding

Answer 4

Elements give up valence electrons (e.g., NaCl - Na donates electron to Cl)

Question 5

Covalent Bonding

Answer 5

Sharing valence electrons (e.g., Hâ‚‚O - Oxygen shares electrons with two hydrogen atoms)

Question 6

Bond Hybridization

Answer 6

Combining orbitals causing overlap (e.g., in carbon)

Question 7

Metallic Bonds

Answer 7

Electrons drift throughout structure acting as ‘glue’; results in good conductivity

Question 8

Van der Waals Bonds

Answer 8

Exist in all molecules, particularly non-polar molecules; very weak

Question 9

Hydrogen Bonding

Answer 9

Special bonds with hydrogen

Question 10

Point Defects

4

Answer 10

Vacancy (atom missing), Self-Interstitial (atom overlaps another), Impurity (different atom), Cation Interstitial (cation overlaps another cation)

Question 11

Linear Defects

Answer 11

Edge Dislocation (shifting of plane causing gaps), Screw dislocation, Burger Vector (denotes change in molecule)

Question 12

Planar Defects

3

Answer 12

Twin (straight parallel axis), Stacking Fault (stacking sequence of close-packed planes), Grain Boundary (separates two small grains)

Question 13

Defect Structures in Ceramics

Answer 13

Electron Neutrality (equal positive and negative charges), Frenkel Defect (cation in wrong spot), Schottky Defect (missing cation-anion pair)

Question 14

Diffusion Types

Answer 14

Interdiffusion (between different atoms), Self-diffusion (same type of atom)

Question 15

Diffusion Mechanisms

Answer 15

Vacancy diffusion (atoms move into vacant sites), Interstitial diffusion (atoms squeeze between other atoms)

Question 16

Ficks First Law

Answer 16

J = -D(dC/dx) for constant diffusion

Question 17

Ficks Second Law

Answer 17

Concentration gradient changes with time

Question 18

Temperature Effect on Diffusion

Answer 18

D = De^(-Q/RT); higher temperature means faster diffusion

Question 19

Crystal Structures - FCC

Answer 19

4 total atoms per unit cell, APF = 0.74, Coordination number = 12

Question 20

Crystal Structures - BCC

Answer 20

2 total atoms per unit cell, APF = 0.68, Coordination number = 8

Question 21

Crystal Structures - HCP

Answer 21

APF = 0.74, Coordination number = 12

Question 22

Crystallographic Directions

Answer 22

Specified as [uvw] (e.g., [100], [110])

Question 23

Crystallographic Planes

Answer 23

Specified as (hkl) (e.g., (100), (110))

Question 24

Braggs Law

Answer 24

nλ = 2d*sinθ¸ (X-ray diffraction)

Question 25

Metals

Answer 25

Dense, stiff, strong, ductile, good conductors (e.g., Iron, aluminum, copper, nickel)

Question 26

Ceramics

Answer 26

Stiff, hard, brittle, insulating (e.g., Aluminum oxide, silicon dioxide, carbides)

Question 27

Polymers

Answer 27

Low density, ductile, insulating, poor temperature resistance

Question 28

what are the Polymer Structures | 4

Answer 28

Linear, Branched, Crosslinked, Network

Question 29

Polymer Configurations on a chain

Answer 29

Isotactic (zigzag), Syndiotactic (alternating), Atactic (random)

Question 30

Polymer Geometric Isomers

Answer 30

Cis (rubbery), Trans (rigid)

Question 31

how are Copolymers assorted

Answer 31

Random, Alternating, Block

Question 32

Composites

Answer 32

Combination of two or more materials for specific properties

Question 33

Thermal Properties

Answer 33

Heat Capacity (absorbs heat), Thermal Expansion (ΔL = αLΔT), Thermal Conductivity (q = -k(dT/dx))

Question 34

Material Analysis Techniques

Answer 34

Microscopy, Electron Microscopy

Question 35

Sample Preparation Process

Answer 35

Sectioning, Grinding/Polishing, Etching