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Expired European patentEurope

High-strength multi-phase silicon nitride ceramic material and process for the production of the same

EP 0447470 B1 · Applicant: HOECHST AKTIENGESELLSCHAFT

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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 November 18, 1989 and granted April 20, 1994. A European patent lasts at most 20 years from filing, so its term ended November 18, 2009.
  • 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 May 18, 2015.
  • 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.
FiledNovember 18, 1989
PublishedSeptember 25, 1991
GrantedApril 20, 1994
Term endedNovember 18, 2009
Application numberEP 90900811
Classification (CPC)C04B35/584

Timeline

Timeline From EPO dates

1990199219941996199820002002200420062008Application filedNov 18, 1989PublishedSep 25, 1991Patent grantedApril 20, 1994Term endedNov 18, 2009

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

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