Kovar™ A

General Characteristics of Kovar™ A

A nickel-cobalt-iron alloy ideal for sealing into hard glass, Kovar A offers similar expansion curve as glass. Resists amalgamation with mercury as well as high thermal shock and creates strong metal-glass bond.

Chemical Composition of Kovar™ A

  • Nickel 28.70-29.20
  • Cobalt 17.30-17.80
  • Manganese 0.50 max
  • Silicon 0.20 max
  • Carbon 0.06 max
  • Iron 52.90-53.40

Heat Treatment of Kovar™ A

  • Anneal 1292° to 2012° F (700° to 1100°C)
  • Air anneal at temperatures less than 1652° F (900°C) after removing surface scale; avoid oxidation by hydrogen annealing

Applications of Kovar™ A

  • Perfect when a vacuum-tight, metal-glass seals are required
  • Grid-glow tube
  • Ignitrons
  • Rectifiers

Machinability of Kovar™ A

  • Slow speeds and standard high-speed cutting tools
  • Lard oil recommended for fine finish
  • Grind high-speed, single-point turning tools to 6-8° side rake, 8-12° back rake, 5-8° side clearance, 7-10° front clearance, 10-15° cutting-edge angle, 10-15° lead angle
  • 7-10° back rake, 5-8° side rake for cutoff blades
  • Stone cutting edge post-grinding

Workability of Kovar™ A

      • Easily hot or cold worked
      • Deep draw maximum reductions:
        • 40% first draw
        • 25% first redraw
        • 30% after reanneal
        • 20% later redraws
        • 25% after reanneal

       

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