| 摘要 |
An insulator for a spark ignition device is disclosed which includes an electrically insulating ceramic core tube having a terminal end, a firing end and an inner bore which extends along a longitudinal bore axis from the terminal end to the firing end and an electrically insulating, ceramic core nose tube having a second outer surface and a second bore where the second outer surface of said ceramic core nose tube is in nested engagement with and directly bonded to the bore of the ceramic core tube proximate the firing end. The insulator also may include a similarly nested and directly bonded shoulder tube on an outer surface of the core tube, or a nested and directly bonded mast tube on an outer surface of the core tube. The ceramics may include alumina-based ceramics, as well other suitable ceramic materials, and the tube may be made from the same ceramic compositions or different ceramic compositions. The invention also includes a method of making the nested tube, directly boded insulators by controlling shrinkage during sintering.
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