EP 0931849 A3 20000802 - Process suitable to give a direct protection against the wear corrosion of metallic pieces
Title (en)
Process suitable to give a direct protection against the wear corrosion of metallic pieces
Title (de)
Verfahren zum direktem Schutz gegen Verschleiss-Korrosion von metallischen Gegenständen
Title (fr)
Procédé de protection directe contre l'usure-corrosion de pièces métalliques
Publication
Application
Priority
IT MI980131 A 19980126
Abstract (en)
[origin: EP0931849A2] In a process suitable to give a direct protection against the corrosion of metallic pieces, a nitrogen diffusion area is realised on the outer layer with a maximum depth of 0.1 mm, and with a nitrogen weight % lower than 2-4%, depending on the steel to he treated. The nitrogen is diffused into the piece and fills the imperfections and the empty areas of the crystal lattice. The temperature at which this first phase takes place goes from 480 to 525 DEG C depending from the steel type and the maximum duration is of 10 hours. Then, both the temperature values and the gas mixture, by introducing an oxidising atmosphere, are changed and the nitrogen diffusion is fully stopped by the oxygen action of the oxidising atmosphere against the iron atoms of the surface. Layers of Fe3O4 at 95-99% content are obtained, practically FeO/Fe2O3 oxides free, which are formed at temperatures comprised between 505 and 545 DEG C and which are comprised between 2 and 4 mu m and containing an oxygen weight % between 25% and 30%. A strong barrier and insulation effect is thereby obtained directly within the steel.
IPC 1-7
IPC 8 full level
C23C 8/34 (2006.01)
CPC (source: EP)
C23C 8/34 (2013.01)
Citation (search report)
- [A] EP 0534010 A1 19930331 - NITREX METAL INC [CA]
- [A] US 2343418 A 19440307 - LAMPTON GLEN T, et al
- [A] EP 0299625 A2 19890118 - LUCAS IND PLC [GB]
- [A] US 4496401 A 19850129 - DAWES CYRIL [GB], et al
- [A] PATENT ABSTRACTS OF JAPAN vol. 1995, no. 04 31 May 1995 (1995-05-31)
- [A] PATENT ABSTRACTS OF JAPAN vol. 005, no. 124 (C - 066) 11 August 1981 (1981-08-11)
- [A] PATENT ABSTRACTS OF JAPAN vol. 013, no. 286 (C - 613) 29 June 1989 (1989-06-29)
Designated contracting state (EPC)
AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE
DOCDB simple family (publication)
EP 0931849 A2 19990728; EP 0931849 A3 20000802; EP 0931849 B1 20030528; AT E241711 T1 20030615; DE 69815051 D1 20030703; DE 69815051 T2 20040408; ES 2201405 T3 20040316; IT 1298200 B1 19991220; IT MI980131 A1 19990726
DOCDB simple family (application)
EP 98203391 A 19981009; AT 98203391 T 19981009; DE 69815051 T 19981009; ES 98203391 T 19981009; IT MI980131 A 19980126