| 摘要 |
To securely seat a ceramic electrode (23, 28) in an insulator (15) of a spark plug, so that it can be sintered together with the insulator, a ceramic plug element (28) has added thereto an additive which renders the ceramic plastically deformable upon application of external energy; the additive may, for example, be a thermoplastic, which permits plastic deformation upon application of heat; or a thixotropic agent, such as glycerin, rendering the material plastically deformable when vibrated. A pellet or plug (28) is introduced into the end portion (32) of the central opening (21) of the insulator, preshaped to be slightly smaller by, for example, 0.2 mm, than the clearance opening in the insulator. The plug is then rendered plastically deformable, compressed by a plunger (34/1) acting against a counter plate (33). Either the plug or the inner surface of the bore can be coated with a conductive coating (27) including a burn-spark-resistant metal, for example platinum, which, upon compression, is not electrically interrupted. In subsequent heating steps, the additive is vaporized-off, and the plug sintered to the ceramic body which, initially, was only presintered.
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