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Stable Kovar 4j29 Rod, Expansion Precision Alloy Rod for Glass-to-Metal Seal

China Stable Kovar 4j29 Rod, Expansion Precision Alloy Rod for Glass-to-Metal Seal, Find details about China Kovar, 4j29 Rod from Stable Kovar 4j29 Rod, Expansion Precision Alloy Rod for Glass-to-Metal Seal

Density
8.2 g/cm3
Trademark
OHMALLOY
Transport Package
with Wooden Box
Specification
Dia: 5mm-200mm; length: 20mm-2000mm
Origin
China(Shanghai)
HS Code
7202999000
Density
8.2 g/cm3
Trademark
OHMALLOY
Transport Package
with Wooden Box
Specification
Dia: 5mm-200mm; length: 20mm-2000mm
Origin
China(Shanghai)
HS Code
7202999000

OhmAlloy-4J29 (Expansion alloy)
(Common Name: Kovar, Nilo K, KV-1, Dilver Po, Vacon 12)

OhmAlloy-4J29 also known as Kovar alloy. it was invented to meet the need for a reliable glass-to-metal seal, which is required in electronic devices such as light bulbs, vacuum tubes, cathode ray tubes, and in vacuum systems in chemistry and other scientific research. Most metals cannot seal to glass because their coefficient of thermal expansion is not the same as glass, so as the joint cools after fabrication the stresses due to the differential expansion rates of the glass and metal cause the joint to crack.

OhmAlloy-4J29was invented to meet the need for a reliable glass-to-metal seal, which is required in electronic devices such as light bulbs, vacuum tubes, cathode ray tubes, and in vacuum systems in chemistry and other scientific research. Most metals cannot seal to glass because their coefficient of thermal expansion is not the same as glass, so as the joint cools after fabrication the stresses due to the differential expansion rates of the glass and metal cause the joint to crack.

OhmAlloy-4J29 not only has thermal expansion similar to glass, but its nonlinear thermal expansion curve can often be made to match a glass, thus allowing the joint to tolerate a wide temperature range. Chemically, it bonds to glass via the intermediate oxide layer of nickel oxide and cobalt oxide; the proportion of iron oxide is low due to its reduction with cobalt. The bond strength is highly dependent on the oxide layer thickness and character. The presence of cobalt makes the oxide layer easier to melt and dissolve in the molten glass. A grey, grey-blue or grey-brown color indicates a good seal. A metallic color indicates lack of oxide, while black color indicates overly oxidized metal, in both cases leading to a weak joint.

Stable Kovar 4j29 Rod, Expansion Precision Alloy Rod for Glass-to-Metal Seal
 

Application:Mainly used in electric vacuum components and emission control, shock tube, igniting tube, glass magnetron, transistors, seal plug, relay, integrated circuits lead, chassis, brackets and other housing sealing.

Normal composition%

Ni28.5~29.5FeBal.Co16.8~17.8Si≤0.3
Mo≤0.2Cu≤0.2Cr≤0.2Mn≤0.5
C≤0.03P≤0.02S≤0.02  

Tensile Strength, MPa

Code of conditionConditionWireStrip
RSoft≤585≤570
1/4I1/4 Hard585~725520~630
1/2I1/2 Hard655~795590~700
3/4I3/4 Hard725~860600~770
IHard≥850≥700

Typical Physical properties

Density (g/cm3)8.2
Electrical resistivity at 20ºC(Ωmm2/m)0.48
Temperature factor of resistivity(20ºC~100ºC)X10-5/ºC3.7~3.9
Curie point Tc/ ºC430
Elastic Modulus, E/ Gpa138


Coefficient of expansion

θ/ºCα1/10-6ºC-1θ/ºCα1/10-6ºC-1
20~607.820~5006.2
20~1006.420~5507.1
20~2005.920~6007.8
20~3005.320~7009.2
20~4005.120~80010.2
20~4505.320~90011.4



Thermal conductivity

θ/ºC100200300400500
λ/ W/(m*ºC)20.621.522.723.725.4

 

The heat treatment process
Annealing for stress reliefHeated to 470~540ºC and hold 1~2 h. Cold down
annealingIn vacuum heated to 750~900ºC
Holding time14 min~1h.
Cooling rateNo more than 10 ºC/min cooled to 200 ºC


Style of supply

Alloys NameTypeDimension 
OhmAlloy-4J29WireD= 0.1~8mm 
OhmAlloy-4J29StripW= 5~250mmT= 0.1mm
OhmAlloy-4J29FoilW= 10~100mmT= 0.01~0.1
OhmAlloy-4J29BarDia= 8~100mmL= 50~1000

Ω

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