 Hot filament CVD of boron nitride films |
| Therefore, it is an object of the present invention to provide a method for coating a boron nitride ... |
|
| Process for depositing a layer containing boron and nitrogen |
| OF PREFERRED EMBODIMENTS The process according to the invention for depositing a layer containing ... |
|
| Process for the preparation of an optical structure and optical structure obtained thereby |
| We claim: 1. A process for producing an optical structure comprising a silicon-based coating on an ... |
|
| Stripping fingers for copying machine |
| OF THE INVENTION The above-described liquid crystal polyester is synthesized from different kinds ... |
|
| Direct positive type silver halide photosensitive material |
| OF THE INVENTION The cobalt, nickel, ruthenium and chromium metal ammine complex salts used in the ... |
|
| Chemically durable nitrogen containing phosphate glasses useful for sealing to metals |
| What is claimed is: 1. An alkali phosphate glass comprising 10-60 mole percent Li.sub.2 O, Na.sub.2 ... |
|
| Spin-on-glass planarization process with ion implantation |
| A principal object of the present invention is to provide an effective and manufacturable method ... |
|
| Liquid two-component coating compositions |
| OF THE PREFERRED EMBODIMENTS The ratio of numbers of functional groups of polyamine curing agents (... |
|
| Method of image formation with a screen element and charging means |
| It is an object of the present invention to present a method of image formation which is carried ... |
|
| Continuous polymerization apparatus and process |
| We claim: 1. A device for the production of water soluble polymers which comprises a tubular ... |
|
|
Method of preparing ferromagnetic material
| Details |
Inventors: Rau, Hans; Knauff, Karl-Georg;
Assignee: U.S. Philips Corporation (New York, NY)
Primary Examiner: Satterfield; Walter R.
Assistant Examiner:
Attorney, Agent or Firm: Trifari; Frank R., Steinhauser; Carl P.
A method of preparing iron powder for recording in which iron oxide hydrate powder is reduced by flowing hydrogen in intimate contact with the iron oxide hydrate powder, preferrably in a fluidized bed. |
|
DETAILED DESCRIPTION What is claimed is: 1.
A method of preparing ferromagnetic material in the form of acicular particles consisting at least predominantly of iron, comprising the steps of reducing an iron oxide or iron oxide hydrate powder by intimately contacting the powder with a quantity of a gaseous reduction agent which predomimantly contains hydrogen flowing at a rate corresponding at least to the formula V = 0.
4 .
times.
T -120, where V is the volume in liters of the quantity of gaseous reduction agent at 0.
degree.
C and 1 atm.
which flows per hour and per gram of Fe contents of the material to be reduced, and T is the reduction temperature in .
degree.
C, T being between 300.
degree.
and 600.
degree.
C.
2.
A method as claimed in claim 1, wherein the reduction is carried out at temperatures between 300.
degree.
and 400.
degree.
C in a single-stage fluidised bed.
3.
A method as claimed in claim 1, wherein the reduction is carried out in a tilting furnace.
4.
A method as claimed in claim 1, wherein the powder is transported from the top to the bottom in counter current with the gaseous reduction agent, and deposited, after successively passing through a plurality of sieves, into a storage container.
5.
A method as claimed in claim 4, wherein successive sieves move relative to each other in opposite directions.
Description:
The invention relates to a method of preparing ferromagnetic material which shows the form of a powder of acicular particles consisting at least predominantly of iron, by reduction of iron oxide powder and/or iron oxide hydrate powder possibly containing additives, by means of a gaseous reduction agent which predominantly contains hydrogen.
Such ferromagnetic materials are used, for example, in the manufacture of magnetic information memories (magnetic tapes, magnetic discs).
Said materials contain, for example, Ge, Sn, Al, Ag, Ni and Co as additives.
U.
S.
Pat.
No.
3,598,568 describes reducing tin-doped acicular iron oxide hydrate with flowing hydrogen at 250
|
| Related patents |
|
|
Acicular .alpha.-iron particles, their preparation and recording media employing same
OF THE INVENTION The crux of the present invention lies in the hydrogen reduction of acicular particles of .alpha.-FeOOH which are intimately codispersed with calcium ...
|
|
|
Stable colloidal dispersions of triacontanol
OF THE INVENTION The stable colloidal dispersions of the present invention allow for the uniform application of a large number of very small crystalline triacontanol ...
|
|
|
Variable preload ball drive
OF THE INVENTION Referring to the drawings for the purposes of illustrating the preferred embodiment of the invention only, and not for the purpose of limiting the same,...
|
|
|
Patterning process for bipolar optical storage medium
OF THE INVENTION FIG. 1 illustrates a prior art optical storage device 1 having, for example, a plurality of concentric tracks 2, a few of which are shown. Each track 2 ...
|
|
|
Master disc for an optical disc and method for manufacturing the master disc
In view of the foregoing, it is an object of the present invention to provide a master disc and a method for manufacturing the master disc in which a plurality of pits ...
|
|
|
Cubic boron nitride preparation
AND BEST MODE The invention provides for deposition of cubic boron nitride on a substrate through activated reactive evaporation by a method which includes: (a) ...
|
|
|
Cubic boron nitride preparation
OF THE INVENTION The invention involves the deposition of CBN on a substrate through activated reactive evaporation including the steps of (a) heating the substrate in ...
|
|
|
Method of producing thin, hard coating
An object of this invention is the provision of a hard, tenacious, anti-galling and corrosion-resistant coating on at least the seal gland and bearing surfaces of a ...
|
|
|
Process for production of high-hardness boron nitride film
Proceeding from the above-mentioned background, research was performed, and as a result, it was found that when vacuum deposition and ion irradiation are carried out on ...
|
|
|
Method of making mixed nitride films with at least two metals
It is an object of the present invention is to solve the aforementioned problems by providing mixed nitride films particularly adapted to different requirements. The ...
|
|
|
Manufacturing Materials 
