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Expired European patentEurope

Process for preparing silicon nitride

EP 0442032 B1 · Applicant: NORTON COMPANY

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Overview

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Listed from its EPO record in Patent Yard's archive of European patents past their term. Its claims, description and drawings are in the EPO PDF and on Google Patents, and the Claude kit works from them.

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Why it's free to use

  • Filed August 28, 1990 and granted May 4, 1994. A European patent lasts at most 20 years from filing, so its term ended August 28, 2010.
  • A supplementary protection certificate, which can extend a medicine or crop-protection patent, adds at most five and a half years, so even that would have ended by February 28, 2016.
  • We check European rights only. A US or other national patent in its family could still be in force: check its family on Espacenet or Google Patents.
FiledAugust 28, 1990
PublishedAugust 21, 1991
GrantedMay 4, 1994
Term endedAugust 28, 2010
Application numberEP 90116511
Classification (CPC)C01B21/0682

Timeline

Timeline From EPO dates

1991199319951997199920012003200520072009Application filedAug 28, 1990PublishedAug 21, 1991Patent grantedMay 4, 1994Term endedAug 28, 2010

Sources & verification

Official EPO records

Full published documentClaims, description and drawings as a PDF.EPOEuropean Patent RegisterProcedure, status, file inspection and legal events.EPOLinked open EP data recordThe bibliographic record this page is built from.EPO

Cross-check elsewhere

Google PatentsFull text, worldwide family, citing patents and legal events.patents.google.comEspacenetNational family members and their legal status.European Patent Office

Everything on this page comes from the EPO record linked above. EPO data used under CC BY 4.0.