GB678715A - Improvements in or relating to the formation of electrically insulating surfaces on ferrous metal laminations - Google Patents
Improvements in or relating to the formation of electrically insulating surfaces on ferrous metal laminationsInfo
- Publication number
- GB678715A GB678715A GB188/49A GB18849A GB678715A GB 678715 A GB678715 A GB 678715A GB 188/49 A GB188/49 A GB 188/49A GB 18849 A GB18849 A GB 18849A GB 678715 A GB678715 A GB 678715A
- Authority
- GB
- United Kingdom
- Prior art keywords
- per cent
- atmosphere
- water
- laminations
- oxide film
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
- C21D1/76—Adjusting the composition of the atmosphere
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/02—Pretreatment of the material to be coated
Abstract
In a method of heat-treating porous metal laminations to remove stresses and provide a highly insulating oxide film thereon, the laminations are heated to above 570 DEG C in a reducing atmosphere to reduce any surface oxides present and relieve stresses, cooled in a reducing atmosphere and, while in the range 450-550 DEG C subjected to an atmosphere composed of at least 20 per cent of water or a mixture of water and carbon dioxide, the balance comprising at least one gas from the group consisting of hydrogen, carbon monoxide, and nitrogen, the volume ratio H2O to O2 being greater than 0.25, the volume ratio CO2 to CO being greater than 1.2 when both are present, and the free oxygen being less than 1/2 of 1 per cent, the time of treating at 450-550 DEG C being sufficient to produce a film of Fe3O4. The initial atmosphere may be water vapour, or an atmosphere of a combusted gas analyzing 15 per cent water, 12 per cent carbon dioxide, 5.4 per cent carbon monoxide, 3 per cent hydrogen, and the balance nitrogen may be used. The time of treatment may be four hours. The laminations may be removed from the furnace, which may be of the batch or of the continuous type, at a temperature between 300 DEG C and 100 DEG C and cooled in air. The Specification as open to inspection under Sect. 91, relates also to the formation of an oxide film when the original surface is not contaminated with any other oxide film. It also refers to a temperature range of 400-570 DEG C. This subject-matter does not appear in the Specification as accepted.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US678715XA | 1948-01-15 | 1948-01-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB678715A true GB678715A (en) | 1952-09-10 |
Family
ID=22078973
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB188/49A Expired GB678715A (en) | 1948-01-15 | 1949-01-04 | Improvements in or relating to the formation of electrically insulating surfaces on ferrous metal laminations |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB678715A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2123443A (en) * | 1982-07-06 | 1984-02-01 | Xerox Corp | Oxidized steel carrier particles for electrostatographic developer |
-
1949
- 1949-01-04 GB GB188/49A patent/GB678715A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2123443A (en) * | 1982-07-06 | 1984-02-01 | Xerox Corp | Oxidized steel carrier particles for electrostatographic developer |
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