Centre National De La Recherche Scientifique

Rhone-poulenc Chimie

Technogenia S.a.

Rene Perrier De La Bathie

Francoise Seon

Daniel Fruchart

Guy Maybon

Salvatore Miraglia

Robert Tournier

Paul Mollard

Pierre Brunet

Robert Fruchart

Paul Michel

Beatrice Legrand

Fortunat Esnault

Joel Chavanne

Method for obtaining a solid, magnetically anisotropic material, includes the steps of heating an alloy containing a rare earth element and at least one transition metal to a temperature higher than the melting temperature of the alloy and sufficient that alloy is completely liquid, and cooling the melted alloy at a rate at least equal to natural cooling in the presence of a continuous, static magnetic field to solidify the alloy and obtain the magnetically isotropic material.

Method for preparing a rare earth- and transition metal-based magnetically anisotropic material by solidifying a liquid alloy in a guiding field

There is disclosed a process for optimizing the magnetic properties of a multiphase product of composition rare earth/iron/boron endowed with permanent magnet properties at ambient temperature. This composition serves as a precursor, which is first subjected to a decrepitation treatment by hydrogenation under low pressure at low temperature to obtain an intermediate hydride in pulverulent form. The pulverulent intermediate hydride is subsequently subjected to a first heat treatment under vacuum for partial dehydrogenation at a temperature below its element separation temperature. The non-separated product thereby obtained is subjected to a second heat post-treatment under an initial primary vacuum and extensively dehydrogenated until the primary vacuum is reestablished at a temperature close to 600.degree. C. The precursor can be an isotropic material obtained by fast quenching, such as wheel quenching or hot welding with a forging ratio of at least 10. According to another aspect of the invention the dehydrogenated product obtained is subjected to a third heat post-treatment under a neutral atmosphere or under vacuum, at a temperature of between 450.degree. and 1000.degree. C. The two post-treatments are optionally separated by a thermal plateau.

Treatment of pulverant magnetic materials and products thus obtained

Process for preparing permanent magnets by division of crystals

Phosphates, e.g., the polyphosphates and halophosphates, are prepared in high purity by melt thermocondensing corresponding precursors thereof, e.g., salts of orthophosphoric, pyrophosphoric or metaphosphoric acid, via electromagnetic induction heating, for example in an auto-crucible furnace.

Preparation of phosphates by induction melting

A method and device are provided for producing refractory materials by induction, in which process a mixture of material powders and a binder in solution in water are compacted by extrusion so as to form a solid bar. The bar is introduced into a cold crucible and is caused to melt by magnetic induction. The molten material flows through a lower orifice of the crucible. The invention applies more particularly to the melting of tungsten carbide.

Method and device for producing refractory materials by induction

Growing community of inventors

Saint Pierre d'Albigny, France

Rene Perrier De La Bathie