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Process for joining alumina ceramic bodies

  • US 5,954,900 A
  • Filed: 09/23/1997
  • Issued: 09/21/1999
  • Est. Priority Date: 10/04/1996
  • Status: Expired due to Term
First Claim
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1. A process for forming a long-time-vacuum-tight, high-strength, and corrosion-resistant joint, by means of a joining material, between a first body and a second body each made of sintered, polycrystalline alumina ceramic with a purity greater than 92 wt. % or of sapphire, said process comprising steps of:

  • interposing the joining material in the form of a paste, a foil, or a slip between the first body and the second body,the joining material having been made froman agglomerate-free, high-purity α

    -alumina powder with particles of a size not exceeding 100 nm (=10-7 m),an anorganic oxidic powder of an auxiliary sintering agent with particles of a size not exceeding 100 nm, and an organic vehicle which is dissolved or suspended in an organic or aqueous solvant and in which the particles of the respective powder are substantially evenly distributed,with the total α

    -alumina and auxiliary-sintering-agent content of the paste, the foil, or the slip ranging between 50% and 70%,or with the joining material having been made froman agglomerate-free, high-purity α

    -alumina powder with particles of a size not exceeding 100 nm (=10-7 m),an anorganic oxidic auxiliary sintering agent produced chemically as envelopes around or attachment to the particles of the α

    -alumina powder, andan organic vehicle dissolved or suspended in an organic or aqueous solvant,with the total α

    -alumina and auxiliary-sintering-agent content of the paste, the foil, or the slip ranging between 50% and 70%; and

    beating the bodies to a temperature of not more than 1,300°

    C. and then allowing them to cool down,with the alumina content of the joint after cooling being at least 95 wt. % and the auxiliary-sintering-agent content after cooling being not more than 5 wt. %.

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