Why should only Europe need to give Shelter to these migrants? Where the fuck is muslim Ummah (UAE, Pakistan, Dubai, Iran etc)?? These migrants are crossing sea because these muslim countries are not allowing them to enter in to their countries (UAE, Pakistan, Dubai, Iran etc). They should give asylum to these people rather than giving money for mosques in Europe. Sheikhs of Dubai and UAE are busy in fucking and partying when their muslim brothers are hungry. Where the fuck is Muslim Ummah?? They (previous migrants) do not respect European culture. They (previous migrants) are not educated so giving them job will be a problem (problem for economy). They abuse European Woman, They don't respect their law. These Muslim immigrants are involved in riots in Scandinavian countries . What, Europeans are doing, is a reflection of their previous learning about muslim immigrants. If American are so worried about them than why not America give them asylum.These muslim immigrants are spreading Antisemitism in Europe. There are some good Muslims but they got fucked not because of European Conspiracy but Because of cheater Muslim Ummah. I feel quite bad about the sufferings of these poor migrants. 8-9 % muslims divided India in 1947 and created a terrorist state named Pakistan (of course with British help). Now Brits are facing same problem in London. Germany is doing good for humanitarian point of view. Thumbs UP Germany . But strategic point of view should be considered because this will change the demographics of Germany in next 100 years. Hungary, you are doing over-drama. Only a gentle No was suffice. Hungarian (sorry for generalization) are not better than those muslim Ummah country muslims. "KICK the ass of woman with camera". Are Germany, Poland idot, they stop our IT personals and allow thousands of migrants? Only soluition of this problem is give to Asylum ill or super needy migrants in Europe. Kick Asses of Muslim Nations so that they give Asylum to these refugees. That will also help these refugees to have a similar cultural environment rather than European countries which are more alien to them culturally.
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Tuesday, September 29, 2015
Invar and Other Low-Expansion Alloys
In
1896, Charles-Edouard Guillaume of France made an interesting and important
discovery that earned him the 1920 Nobel Prize in Physics; his discovery: an
iron–nickel alloy that has a very low (near-zero) coefficient of thermal
expansion between room temperature and approximately 2300C. This
material became the forerunner of a family of “low-expansion”(also sometimes
called “controlled expansion”) metal alloys. Its composition is 64 wt% Fe–36
wt% Ni, and it has been given the trade-name of “Invar” since the length of a
specimen of this material is virtually invariable with changes in temperature. Its
coefficient of thermal expansion near room temperature is 1.6 X 10-6(0C)-1.
One
might surmise that this near zero expansion is explained by a symmetrical
potential energy versus interatomic distance curve. Such is not so; rather,
this behavior relates to the magnetic characteristics of Invar. Both iron and nickel
are ferromagnetic materials .A ferromagnetic material may be made to form a permanent
and strong magnet; upon heating, this property disappears at a specific
temperature, called the “Curie temperature,” which temperature varies from one
ferromagnetic material to another. As a specimen of Invar is heated, its
tendency to expand is counteracted by a contraction phenomenon that is
associated with its ferromagnetic properties (which is termed
“magnetostriction”). Above its Curie temperature (approximately Invar expands
in a normal manner, and its coefficient of thermal expansion assumes a much
greater value. Heat treating and processing of Invar will also affect its
thermal expansion characteristics. The lowest values (α) result for specimens
quenched from elevated temperatures (near 8000C) that are then cold
worked. Annealing leads to an increase in α. Other low-expansion alloys have
been developed.
Other
low-expansion alloys have been developed. One of these is called “Super–Invar” because
its thermal expansion coefficient [0.72 X 10-6(0C)-1]
is lower than the value for Invar. However, the temperature range over which its
low expansion characteristics persist is relatively narrow. Compositionally,
for Super–Invar some of the nickel in Invar is replaced by another ferromagnetic
metal, cobalt; Super–Invar contains 63 wt% Fe, 32 wt% Ni, and 5 wt% Co.
Another
such alloy, with the trade-name of “Kovar,” has been designed to have expansion
characteristics close to those of borosilicate (or Pyrex) glass; when joined to
Pyrex and subjected to temperature variations, thermal stresses and possible fracture
at the junction are avoided. The composition of Kovar is 54 wt% Fe, 29 wt% Ni,
and 17 wt% Co. These low-expansion alloys are employed in applications that
require dimensional stability with temperature fluctuations; these include the following:
•
Compensating pendulums and balance wheels for mechanical clocks and watches.
•
Structural components in optical and laser measuring systems that require
dimensional stabilities on the order of a wavelength of light.
•
Bimetallic strips that are used to actuate microswitches in water heating
systems.
•
Shadow masks on cathode ray tubes that are used for television and display
screens; higher contrast, improved brightness, and sharper definition are
possible using low-expansion materials.
•
Vessels and piping for the storage and piping of liquefied natural gas.
Environmental
Properties:
|
|
Resistance Factors : 1=Poor 5=Excellent
|
|
Flammability
|
5
|
Fresh
Water
|
5
|
Organic
Solvents
|
5
|
Oxidation
at 500C
|
5
|
Sea
Water
|
5
|
Strong
Acid
|
4
|
Strong
Alkalis
|
5
|
Material
|
Invar - Nickel Iron Alloy
|
|||||
Property
|
Minimum Value (S.I.)
|
Maximum Value (S.I.)
|
Units (S.I.)
|
Minimum Value (Imp.)
|
Maximum Value (Imp.)
|
Units (Imp.)
|
Atomic Volume (average)
|
0.0068
|
0.0071
|
m3/kmol
|
414.961
|
433.268
|
in3/kmol
|
Density
|
8.1
|
8.2
|
Mg/m3
|
505.667
|
511.91
|
lb/ft3
|
Energy Content
|
50
|
200
|
MJ/kg
|
5416.93
|
21667.7
|
kcal/lb
|
Bulk Modulus
|
106
|
112
|
GPa
|
15.374
|
16.2442
|
106 psi
|
Compressive Strength
|
240
|
725
|
MPa
|
34.8091
|
105.152
|
ksi
|
Ductility
|
0.06
|
0.45
|
0.06
|
0.45
|
||
Elastic Limit
|
240
|
725
|
MPa
|
34.8091
|
105.152
|
ksi
|
Endurance Limit
|
185
|
405
|
MPa
|
26.832
|
58.7402
|
ksi
|
Fracture Toughness
|
120
|
150
|
MPa.m1/2
|
109.206
|
136.507
|
ksi.in1/2
|
Hardness
|
1200
|
2400
|
MPa
|
174.045
|
348.091
|
ksi
|
Loss Coefficient
|
0.0003
|
0.0011
|
0.0003
|
0.0011
|
||
Modulus of Rupture
|
240
|
725
|
MPa
|
34.8091
|
105.152
|
ksi
|
Poisson's Ratio
|
0.28
|
0.3
|
0.28
|
0.3
|
||
Shear Modulus
|
54
|
58
|
GPa
|
7.83204
|
8.41219
|
106 psi
|
Tensile Strength
|
445
|
810
|
MPa
|
64.5418
|
117.481
|
ksi
|
Young's Modulus
|
137
|
145
|
GPa
|
19.8702
|
21.0305
|
106 psi
|
Glass Temperature
|
K
|
°F
|
||||
Latent Heat of Fusion
|
270
|
290
|
kJ/kg
|
116.079
|
124.677
|
BTU/lb
|
Maximum Service Temperature
|
600
|
700
|
K
|
620.33
|
800.33
|
°F
|
Melting Point
|
1690
|
1710
|
K
|
2582.33
|
2618.33
|
°F
|
Minimum Service Temperature
|
0
|
0
|
K
|
-459.67
|
-459.67
|
°F
|
Specific Heat
|
505
|
525
|
J/kg.K
|
0.390798
|
0.406276
|
BTU/lb.F
|
Thermal Conductivity
|
12
|
15
|
W/m.K
|
22.4644
|
28.0805
|
BTU.ft/h.ft2.F
|
Thermal Expansion
|
0.5
|
2
|
10-6/K
|
0.9
|
3.6
|
10-6/°F
|
Breakdown Potential
|
MV/m
|
V/mil
|
||||
Dielectric Constant
|
||||||
Resistivity
|
75
|
85
|
10-8 ohm.m
|
75
|
85
|
10-8 ohm.m
|
Labels:
Alloy,
Charles-Edouard Guillaume,
expansion,
iron,
Kovar,
magnetostriction,
nickel,
zero
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