Lectures 4-7 Flashcards Preview

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Flashcards in Lectures 4-7 Deck (23)
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1

Hardness

The property of a material that enables it to resist plastic deformation, penetration, indentation and scratching.

2

Moh's scale

A scale using minerals which increasing with hardness

3

What are the three hardness test?

Brinell, Vickers and Rockwell

4

Brinell

-Static load, 100-3000kgf
-Ball diameter, 1-10mm
Dwell time, 10-30 seconds

5

How do you calculate and write Brinell's number?

BH=force/impression of indentation
Number/sphere type/diameter/load/time

6

Vickers

Load:
-Micro- 10g-1kg
-Macro-1-100kg
Dwell time 10-15s
a diamond with an edge at 136 degrees

7

VH calculation and number?

VH=force/surface area of impression
Number/HV/loadkgf

8

Rockwell

Load:
Minor:10kgf
Major:60, 100 and 150kgf
Uses a minor load to cause an indentation and then the major load is added to make an impression.

9

Specific heat capacity

The amount of energy used to change the temperature of an object per unit mass
Q=mcΔT
c=secifitic heat capacity

10

How to calculate the linear heat coefficient of thermal expansion?

-ε=a*change in temperature
a=change in length/ original length*change in temperature

11

How does the linear, area, and volume coefficient to thermal expansion change with each dimension?
(what the equation?)

Change in length=a*change in temperature
Change in area=2a*change in temperature
Change in volume3a*change in temperature

12

Fourier's law

heat flux=thermal conductivity/temperature gradient
q=-k(dT/dx)

13

Thermal stress

σ=Ea*change in temperature
E=youngs modulus

14

Lattice

A three-dimensional array of points with the identical surrounding.

15

Unit cell

The smallest repetitive volume which contains the complete lattice pattern of the crystal.

16

SC
BCC
FCC

Four in cube
four in a cube with one in the middle
four in a cube, with one in between each cube.

17

what are the four-point defects

-vacancies
-interstitial atom
-Small substitution atom
-Large substitution atom

18

Line defects

Dislocation: screw and edge
produce permanent plastic deformation

19

Grain boundaries

Are the 2D representation of the material.
Effects conductivity and strength of an object

20

Binary system

A system consisting of two materials

21

Gibbs phase rule

F+V=C+n
V=variance
C=number of components
F=number of phases that coexist
n=physucal variables
-For constant pressures
F+V=C+1

22

The Lever Rule

-Shows the amount of liquid to solid ratio.
Wa=R/R+Q
R+Q=100%
R=ratio of liquid
Q=ratio of solid

23

Binary system

A material with two or more substances, represented using a graph with percentage of weight on the x-axis