The commonly used carbon in vacuum technique is artificial black lead. Watch 24 gave out certain property of carbon. Carbolic melting point depress of tall, steam, thermal conductance the transgression meritorious service that good, electron launchs tall, conductivity is tall, hot emissive rate stability of tall, chemistry, stiffness is big, inspiratory the gender is good and low-cost. The crucible that consequently black lead can use the heater that makes vacuum oven, plated film and fusion (defect is melt content meeting generation carbon is polluted) , the hot screen cover in metallic plated film and arc welding (furnace) medium electrode. Carbon still can be used at raising hot emissive rate, restrained an electron 2 times at the same time blast off, be like carbon of nickel besmear Fu. Main drawback of carbon is intensity low, contain tolerance big, go enraging sex of difficult, machining it is poor, difficult to solder.
Atomic weight
Density
Melting point
Specific heat
The line heats up coefficient of expansion
Hardness of cloth family name
Tensile strength
Yang model is measured
Resistor rate
Electron transgression result
Real value
Express par value
20~300
20~1500
20~100
20
2000
6
12.016
2.21~2.25
1.5~1.75
3700 ± 100
0.20
0.40
Fore-and-aft 11~22 × 10- 7
Transverse 22~46 × 10- 7
≥ 3
0.2~0.6
600~80
Amount to 1000
600~1100
4.0~4.8
G · Cm- 3
℃Cal · G- 1·℃- 1
℃- 1
Kg · Mm- 2Kg · Mm- 2Kg · Mm- 2
Cm of µ Ω ·EV
4.4.2 carbon (black lead) fiber
Carbon fiber is 60 time since a kind of when develop quickly new material. In vacuum technique, in the environment of the electric heat system that it basically uses at adding shrinkage fitting buy, adiabatic layer and anticorrosive heat-resisting. It is having exceedingly good electricity, heat and mechanical quality. Its fiber is one kind is returned than the thread of a spider web fine, lighter than aluminium, more anti-corrosive than stainless steel (be able to bear or endure most chemical reagents is corroded, be opposite only strong oxidant, for example chromate reaction can have below high temperature) , more high temperature resistant than refractory steel, can resemble the new material with electric in that way copper again.
The working temperature of carbon fiber can be amounted to - 3300 ℃ of 180 ～ . Although cool from 3000 ℃ to room temperature also not scamper is cracked. Its cloth is the good data that the advantage provides quite in vacuum electric stove.
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