Sell kovar alloy

Typical Physical Properties:

Density: .**2 lb/in3

Specific Gravity: 8.*6

Curie Temperature: **5C

Melting Point: ***0C

Specific Heat: .**5 cal/gm/C at 0C

.**5 cal/gm/ oC at **0C

Heat of Fusion: *4 cal/gm

Thermal Conductivity: *7.3 W/m · K

Electrical Resistivity: **0 microhm/mm

Typical Mechanical Properties:

Shear Modulus: 7.5 · **6

Modulus of Elasticity: *0 · **6

Ultimate Strength: *5,**0 psi

Yield Strength: *0,**0 psi

Kink Point: **0C

Poisson’s Ratio: **7

Elongation: *0%

Velocity of Sound: *6,**0 ft/sec

Hardness (Rockwell B): *8

Coefficient of Thermal Expansion (Nominal):

*0 C  - **0 C    5.5 (x ***6 m/m · K)    *0 C - **0 C    7.9

*0 C  - **0 C    5.1                                *0 C - **0 C    9.3

*0 C   - **0 C   4.9                                *0 C - **0C    *0.4

*0 C   - **0 C   5.3                                *0 C- **0 C    *1.5

*0 C   - **0 C   6.2

Heat Treatment:
Because of its effect on the actual structure of the material, there is a distinction made between heat treating the material to
facilitate fabrication and heat treating the material to insure optimum conditions for glass sealing, plating or brazing.

Stress Relief Annealing:
To relieve stress and work hardening of parts at intermediate stages of fabrication. It is intended particularly for drawing,

forming and spinning operations.
1. Wash and degrease parts.
2. Anneal in atmosphere controlled furnace. Atmosphere may be wet or dry hydrogen, dissociated ammonia, cracked gas or similar neutral atmosphere.
3. Annealing temperature is not critical; however, high temperatures (greater than **0 C) or extended time periods (longer than *0 minutes) should be avoided because such treatments promote grain growth. Typical cycle: **0C for *0 minutes.
4. Parts should be held at temperature for the indicated time and then furnace cooled to less than **5C to avoid oxidation and/or thermal shock (which may cause distortion).

Heat Treatment for Oxidation:
1. Make sure that proper methods are used to clean, degrease and bright dip parts.
2. Oxidation - Heat treat in an electric air furnace to **0C to **0C until parts are cherry red (dull red heat). The length of heat cycle is approximately 3 minutes, but due to differences in humidity and furnaces, the proper cycle has to be varied. Then reduce heat approximately *0C per minute. When parts are cooled, oxide will be formed. The oxide may appear from light grey to black in color. Black is normally considered to be over oxidation and is not necessarily desirable for a good glass to metal seal.