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Bright Low Expansion Alloys Kovar 4J29 Wire 29HK Wire For Glass Sealing Alloy

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China Ohmalloy Material Co.,Ltd certification
China Ohmalloy Material Co.,Ltd certification
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Bright Low Expansion Alloys Kovar 4J29 Wire 29HK Wire For Glass Sealing Alloy

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Large Image :  Bright Low Expansion Alloys Kovar 4J29 Wire 29HK Wire For Glass Sealing Alloy Get Best Price

Product Details:
Place of Origin: China(Shanghai)
Brand Name: OHMALLOY
Certification: SGS,ISO
Model Number: 4J29
Payment & Shipping Terms:
Minimum Order Quantity: 30KG
Price: 20-50USD/KG
Packaging Details: Plastic shaft, Roll bag, Drum
Delivery Time: 25-35 working days
Payment Terms: L/C, T/T, , MoneyGram
Supply Ability: 25000 KG per month
Detailed Product Description
Material: Fe Ni Alloy Density: 8.2 G/cm3
Wire Diameter Range: 0.05mm-8mm Package: Plastic Shaft, Roll Bag, Drum
Common Name: Kovar, Nilo K, KV-1, Dilver Po, Vacon 12 Surface: Bright
Application: Sealing Material For Glass Temperature Factor Of Resistivity(20℃~100℃)X10-5/℃: 3.7~3.9
High Light:

invar alloy


kovar alloy

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-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.

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%


Ni 28.5~29.5 Fe Bal. Co 16.8~17.8 Si ≤0.3
Mo ≤0.2 Cu ≤0.2 Cr ≤0.2 Mn ≤0.5
C ≤0.03 P ≤0.02 S ≤0.02    

Bright Low Expansion Alloys Kovar 4J29 Wire 29HK Wire For Glass Sealing Alloy 0


Tensile Strength, MPa

Code of condition Condition Wire Strip
R Soft ≤585 ≤570
1/4I 1/4 Hard 585~725 520~630
1/2I 1/2 Hard 655~795 590~700
3/4I 3/4 Hard 725~860 600~770
I Hard ≥850 ≥700


Typical Physical properties

Density (g/cm3) 8.2
Electrical resistivity at 20℃(Ωmm2/m) 0.48
Temperature factor of resistivity(20℃~100℃)X10-5/℃ 3.7~3.9
Curie point Tc/ ℃ 430
Elastic Modulus, E/ Gpa 138

Coefficient of expansion

θ/℃ α1/10-6-1 θ/℃ α1/10-6-1
20~60 7.8 20~500 6.2
20~100 6.4 20~550 7.1
20~200 5.9 20~600 7.8
20~300 5.3 20~700 9.2
20~400 5.1 20~800 10.2
20~450 5.3 20~900 11.4

Thermal conductivity

θ/℃ 100 200 300 400 500
λ/ W/(m*℃) 20.6 21.5 22.7 23.7 25.4


The heat treatment process
Annealing for stress relief Heated to 470~540℃ and hold 1~2 h. Cold down
annealing In vacuum heated to 750~900℃
Holding time 14 min~1h.
Cooling rate No more than 10 ℃/min cooled to 200 ℃

Style of supply

Alloys Name Type Dimension  
OhmAlloy-4J29 Wire D= 0.1~8mm  
OhmAlloy-4J29 Strip W= 5~250mm T= 0.1mm
OhmAlloy-4J29 Foil W= 10~100mm T= 0.01~0.1
OhmAlloy-4J29 Bar Dia= 8~100mm L= 50~1000


Contact Details
Ohmalloy Material Co.,Ltd

Contact Person: Mr. Qiu

Tel: +8613795230939

Send your inquiry directly to us