For Sealing Glass Kovar Alloy/Nilo K/4J29 Strip

For Sealing Glass Kovar Alloy/Nilo K/4J29 Strip
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For sealing glass Kovar alloy/Nilo K/4J29 strip


    4J29 is 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 lig 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.

    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



 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 20C 2mm2/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 ℃

 


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