DE1940464C - Process for increasing the coercive field strength of finely dispersed rare earth cobalt alloys - Google Patents

Claims (4)

ι 2 The invention relates to a method for increasing the deposition of the tin can in various ways the coercive field strength or prevention or prevention. For example, it is possible to use a Reduction of the drop in the coercive field strength of powder-tin-mercury alloy with approx. shaped rare earth cobalt alloys by weight percentage tin with the powdery rare earth Deposition of a metal on the surface of the 5 earth cobalt alloy mix and that Alloy powder. Mercury by heating, possibly in the vacuum Rare earth cobalt alloys are especially hard to remove from the mixture. The severing their way of producing permanent magnets voltage of the mercury takes place at temperatures of suitable, since such alloys in a range of over 200 "C. At these temperatures, too chose area extremely high uniaxial magnetic io already the diffusion of tin: "the alloy Have crystal anisotropy. particle causes. Such alloys for permanent magnets can consist of 10 to 25 atomic percent Y, Sc, La, Ce _1, which are relatively thin layers of tin, by using the finely ground Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm ₇ Yb, Lu, rare earth-cobalt alloy in the aqueous lion, where the elements alone or in a mixture are introduced into a tin salt and can optionally lie, and 75 to 90 atomic percent cobalt is heated. There is a quick and even covering. The cobalt can optionally be obtained as a mixture of the surfaces of the alloy particles, with one or more of the elements manganese, by grinding the iron and / or nickel. Rare earth cobalt alloy in a tin salt The rare 20 solution to be treated according to the invention takes place. To achieve thicker layers Earth-cobalt alloys have the previously set, but it is advisable to apply a given composition. Tension the tin electrolytically on the alloy It is known to be disadvantageous that the powder particles separate out. Particularly good results shaped rare earth-cobalt alloys with nisse are achieved when this deposition with Store a reduction in their coercive field strength 35 low pH values, e.g. at a pH value of show. This decrease in the coercive field strength affects 2 to 4 is made. The solution can be The technical usefulness of such a system needs to be buffered in the usual way in order to achieve constancy Alloy powder. the pH value during the electrolysis It has already been suggested that the alloy sites. powder Li a nickel bath to treat the 30 The heat treatment of the tin-plated Increase coercive field strength. Alloy parts are expediently carried out at temperature It is also known that the coercive force of such doors is above 150 C. It is obvious to those skilled in the art that the acid treatment of rare earths cobalt can be improved with increasing temperature. action time can be reduced. It will desZiel of the invention is, half select a Bchandlungstemperatur a Oberflächenbehand- 35 which development of these rare ^F: .rden-cobalt alloy powder ensures a sufficiently short treatment time, to find, on the one hand the reduction of the inside of a Temperalurintervalls 150 and coercive force at the Storing the powder prevents 500 ° C, the treatment time drops from around 2 hours or the given coercive force of an alloy to a few minutes. pulvcrs of the aforementioned composition increased. 40 The heat treatment can be done with the shaping The coating should be as simple as possible for the rare earth cobalt alloy particles Way to be done. At the same time, the following should be a permanent magnet, possibly with a Formgehiing facilitated as possible and the binding effect of a magnetic field, combined, As mentioned at the beginning, the shape of the to be improved. 45 permanent magnets by pressing and sintering under Surprisingly, it has been found that this is accomplished using a binder. crfindungsgcmüß succeeds in that one on the. A particular advantage of the invention Surface of the powdery rare F.rdcn process lies; in that when using Cobalt alloys deposit tin and the tin or tin gicningcn as Nf: itri \ die with tin Coated powders are then coated at temperatures of alloy layers which are particularly good warms, in which a diffusion of the tin in the size / surface of the surface to the surrounding matrix Surface layers of rare earth cobalt show the mechanical properties of the Lcgicrimgslcilchcn takes place. Magnets are improved. The civic class of the Lc- At least monoatomic tin layers must be coated, but even then this is of particular importance be generated. Particularly good results are important if the matrix is an organic however, achieved with thicker layers if the tin binder is used, which prevents the oxidation of the does not by itself depend on the weight of the alloy-embedded alloy part pulvcrs, elwii 0.1 to 5 "mi. Can prevent. Properly generated The tin layer is capable of this through the inventive heat treatment.
of the coated alloy powder diffuses a 60 ...
Part of the tin layer in the surface layer.
the l.egieriinpteilecliLn a. It is true that the method for increasing the coercive field layers already achieves that the coercive force of the strength or prevention or reduction of the particle is no longer reduced during the agem. Decrease in the coercive field strength in powder form The partial diffusion of the deposited tin 65 Rare Brden-Cobalt-Legicrtingcn by Abhat jcdodi a / critical increase in the coercive separation of a metal on the surface of the force of the 11 rch metal dissipation of the surface structure geke η η ze i chile r particles result. no; t that on the rare earth cobalt alloy Metallic tin is deposited and the sealant Powder is then heated to temperatures at which diffusion of the Zinns in the Oherlläehensehichlen of the alloy parts he follows. 2. The method according to claim 1, characterized in that dnil, based on the weight of the Alloy particles, about 0.1 to 5 weight percent Tin is deposited. 3. The method according to claim 1 or 2, characterized in that for the diffusion of the tin in the OhcrllächcnschichichU'ii of the I ig Chen treated at temperatures above III C. will. 4. Verlahren according to claim I or 2, characterized in that the HudilliMun des /.inns in the Oberlläclii-nschichtcii tier l.cgierunusleilchen iiiul the lorniuehuni; de · »l'.hayered hunting | iuKeis / ti a l'eunanentmauneten, possibly under the influence of a magnetic field, is carried out in one process step.