Abstract: Disclosed is a rare earth-based, magnetically anisotropic permanent magnet material consisting of a rare earth element, e.g., neodymium or praseodymium, iron optional in combination with cobalt and boron and having excellent magnetic properties by virtue of the magnetic coupling between the magnetically hard and soft phases. The magnet material has a structure consisting of crystalline particles of, e.g., Nd.sub.2 Fe.sub.14 B, having a particle diameter of 1 .mu.m or larger and fine crystals of iron of submicron size in a rod-shaped or platelet form precipitated within each crystalline particle of Nd.sub.2 Fe.sub.14 B. This magnet material can be prepared by several different methods including, for example, a solid phase reaction of an intermetallic compound of Nd.sub.2 Fe.sub.17 with boron to effect a double decomposition reaction producing Nd.sub.2 Fe.sub.14 B and iron.

Abstract: Disclosed is a method for the preparation of a novel composite rare earth-based magnetically anisotropic sintered permanent magnet in which: (a) a base alloy consisting of a host phase of R.sub.2 T.sub.14 B (R: a rare earth element; T: iron or a combination of iron and cobalt) having a particle diameter of 2 to 10 .mu.m and containing in each particle a phase rich in the content of T and having a particle diameter not exceeding 1 .mu.m is prepared by the strip casting method; (b) the base alloy is crushed; (c) the base alloy powder is blended in a specified proportion with a powder of an auxiliary alloy of R-T or R-T-B in a specified proportion; (d) the powder blend is subjected to further comminution; (e) the comminuted powder blend is subjected to compression-molding in a magnetic field into a powder compact; and (f) the powder compact is sintered by a heat treatment.

Abstract: An improvement is proposed in the method for the preparation of a magnetic recording medium comprising a non-magnetic substrate plate of silicon and a magnetic recording layer formed on the substrate surface by the method of bias-sputtering, by which the magnetic recording layer can be imparted with an unexpectedly large coercive force. The improvement can be accomplished by the use of a silicon substrate plate which has a volume resistivity not exceeding 2 ohm-cm at room temperature. The improvement is more remarkable when the contact resistance between the silicon substrate plate and the substrate holder is kept not to exceed 10 kohm during the bias-sputtering for the formation of the magnetic recording layer on the substrate surface.

Abstract: The recording sensitivity can be improved of a magneto-optical recording medium having a laminar structure consisting of a first dielectric layer, a recording layer, a second dielectric layer and reflecting layer successively formed on a transparent substrate plate by forming the reflecting layer from an alloy consisting of aluminum and from 0.05 to 3 atomic % of a rare earth element such as neodymium and gadolinium in place of pure aluminum as in conventional magneto-optical recording media.

Abstract: Proposed is a magnetic recording medium consisting of a non-magnetic substrate and a magnetic recording layer formed thereon by the method of sputtering, in which the non-magnetic substrate is a disk of single crystal silicon having a surface of the crystallographic orientation of (100), the surface roughness Rp being 40 nm or smaller. By virtue of the use of the unique material for the substrate, the magnetic recording layer is outstandingly stable as compared with conventional aluminum or glass substrates and the magnetic layer formed thereon by sputtering has a greatly improved coercive force of 1300 oersted or higher.

Abstract: Proposed is a magnetic recording medium consisting of a non-magnetic substrate and a magnetic recording layer formed thereon by the sputtering method, in which the non-magnetic substrate is a disk of single crystal silicon having a surface substantially in parallel with the crystallographic (111) plane with an angle of deviation not exceeding 15.degree., of which the surface roughness Rp does not exceed 25 nm. By virtue of the use of the unique material for the substrate, the magnetic recording layer is outstandingly stable as compared with conventional aluminum or glass substrates and the magnetic layer formed thereon by sputtering has a greatly improved coercive force of 1300 oersted or higher.

Abstract: An improvement is proposed in the method for the preparation of a magnetic recording medium by forming a magnetic recording layer of a magnetic alloy on the surface of a non-magnetic substrate plate of, e.g., silicon so as to impart the magnetic recording medium with improved CSS (contact-start-stop) characteristics still without affecting the magnetic recording density. The improvement can be obtained by subjecting the surface of the substrate plate, prior to the formation of the magnetic recording layer, to a surface-roughening treatment which is performed either by a dry-process such as plasma etching and reactive ion etching or by a wet-process of anisotropic etching by using an aqueous solution of sodium or potassium hydroxide as the anisotropic etching solution. In particular, the plasma etching or reactive ion etching is conducted in the presence of a particulate scattering source body of aluminum, etc.

Abstract: A magneto-optical recording medium having a layered structure consisting of a first dielectric layer, magnetic recording layer, second dielectric layer and reflecting layer successively formed on a transparent substrate plate can be imparted with improved performance relative to the recording sensitivity and the C/N ratio when the recording layer and the second dielectric layer each have such a thickness that the angle .delta. given by the equation .delta.=tan.sup.-1 (.epsilon./.theta.k), in which .epsilon. is the Kerr ellipticity of the regenerative light and .theta.k is the Kerr rotation angle, does not exceed 10.degree., the thickness of the recording layer being in the range from 8 nm to 13.5 nm and the thickness of the second dielectric layer satisfying the relationship given by the inequality0.06.ltoreq.nd/.lambda..ltoreq.0.14,in which d is the thickness of the second dielectric layer, .lambda.

Abstract: An improvement is obtained in the stability and recording density of a magneto-optical recording medium having a laminar structure on a transparent substrate plate successively consisting of a first dielectric layer, a magnetic recording layer, a second dielectric layer and a metallic light-reflecting layer by forming the dielectric layer with a unique and specific dielectric material which is an amorphous composite material comprising boron and hydrogen in a specified weight proportion formed by the method of plasma CVD or sputtering. The dielectric material can be a ternary composite of boron, hydrogen and nitrogen or quaternary composite of boron, hydrogen, nitrogen and silicon or carbon.

Abstract: A rare earth permanent magnet of a composition, Ce(CO.sub.1-x-y-a Fe.sub.x Cu.sub.y M.sub.a).sub.z, where a, x, y, and z are: 0.005<1<0.10; 0.20<x<0.40; 0.10<y<0.30; 4.8<z<6.0; and M is zirconium, titanium, nickel, and/or manganese. A method for manufacturing the magnet is disclosed comprising the steps of: applying a first solid solution heat treatment to an alloy ingot having the above composition at temperatures from 900.degree. to 1100.degree. C. for 10 minutes to 100 hours; pulverizing the alloy ingot; obtaining a magnet body from this pulverized alloy by the powder metallurgy method; sintering the magnet body; applying a second solid solution heat treatment to the sintered magnet body at 900.degree.-100.degree. C. for 10 minutes to 100 hours; and applying aging heat treatment to the sintered magnet.

Abstract: The magnetic properties or, in particular, coercive force of a sintered permanent magnet composed of a light rare earth element, boron and iron can be greatly improved without affecting the residual magnetic flux by the admixture of a relatively small amount of additive elements including heavy rare earth elements, aluminum, titanium, vanadium, niobium and molybdenum. In the inventive magnets, the distribution of the additive element is not uniform but localized in the vicinity of the grain boundaries of the matrix particles. Such a localized distribution of the additive elements is obtain by sintering a powder mixture composed of a powder of an alloy of the base ingredients and a powder containing the additive element or elements.

Abstract: An inner tube for use in a semiconductor diffusion furnace is provided comprising a liner or diffusion tube and an insulating layer formed on the entire outer surface of the tube by spraying, typically plasma spraying. The sprayed insulating layer is resistant to deterioration and peeling, ensuring an extended period of service for the tube.

Abstract: Disclosed is a silicon carbide type diffusion tube comprising a diffusion tube base made of reaction-sintered silicon carbide having an iron concentration of 20 ppm or below and a density of 3.0 g/cm.sup.3 or over, and a silicon carbide layer consisting of a high-purity silicon carbide film having an iron concentration of 5 ppm or below deposited on the inner surface of the tube base and a silicon carbide type diffusion tube comprising a diffusion tube base made of reaction-sintered silicon carbide, and a silicon carbide layer consisting of a Si-depleted layer formed in the inner wall of the reaction-sintered silicon carbide tube base and a high-purity silicon carbide film deposited on the Si-depleted layer, said silicon carbide film having a thickness of more than 0.5 mm.

Abstract: A rare earth permanent magnet of the formulaR(Fe.sub.1-x-y Co.sub.x M.sub.y).sub.z,in which R is rare earth element(s) and/or Y, M is Si, Ti, Mo, B, W, V, Cr, Mn, Al, Nb, Ni, Sn, Ta, Zr, and/or Hf, and x, y, z are numbers such that0.ltoreq.x.ltoreq.0.99,0.01.ltoreq.y.ltoreq.0.03, and8.5<z<12.0,and in which the matrix cells consist of two finely segregated phases.

Abstract: Method of preparing an anisotropic permanent magnet by a powder metallurgical technique, in which, the step of orientation of anisotropically magnetic particles during shaping by compression to give a green body prior to sintering, the magnetic field is applied pulse-wise to the mass of magnetic particles and an impacting compressive force is applied to the thus oriented particles in the direction parallel to the magnetic field during the period in which a pulse of the pulse-wise magnetic field is sustained. This method ensures a much higher degree of particle orientation than in the conventional static-field method by virtue of the possibility of obtaining a much stronger magnetic field without problems which otherwise are unavoidable. The principle of the method is applicable to the preparation of a cylindrical or annular permanent magnet magnetizable in a plurality of radial directions.

Abstract: The invention provides a method for producing a magnetic bias field in a magnetic bubble domain memory device. The method comprises coupling a magnetic bubble domain element with a permanent magnet. The permanent magnet is formed of a rare earth metal-containing alloy for use in the bubble domain memory device in respect of the reversible temperature coefficient of the magnet capable of being in compliance with the temperature coefficient of the bubble disappearance field of the memory device. The alloy characteristically contains nickel as an essential component so that the composition of the alloy is expressed by the formulaR(Co.sub.1-x-y Cu.sub.x Ni.sub.y).sub.z,in which R is a rare earth element, e.g. samarium or cerium, and s, y and z are each a positive number from 0.001 to 0.4, from 0.001 to 0.6 and from 4.0 to 9.0, respectively, with the proviso that x+y is smaller than 1.

Abstract: The permanet magnet composed of a rare earth element, e.g. samarium, and cobalt together with iron, copper and some other additive elements and prepared according to the inventive method has a high coercive force and excellent squareness of the magnetic hysteresis loop despite the relatively low content of copper which has been considered to be indispensable for obtaining a high coercive force. The characteristic feature of the inventive method consists in the aging treatment of the sintered body of the alloy powder of a specified composition undertaken in two or more steps, each being carried out by continuously cooling the sintered body within a specified temperature range at a specified cooling velocity.

Abstract: The invention provides a rare earth metal-containing alloy for permanent magnets having a composition expressed by the formulaSm.sub.1-.alpha. Ce.sub..alpha. (Co.sub.1-x-y-u-v-w Fe.sub.x Cu.sub.y Ti.sub.u Zr.sub.v Mn.sub.w).sub.z,in which the suffixes are each a numerical value as defined by:0.1.ltoreq..alpha..ltoreq.0.90;0.10.ltoreq.x.ltoreq.0.30;0.05.ltoreq.y.ltoreq.0.15;0.002.ltoreq.u.ltoreq.0.03;0.002.ltoreq.v.ltoreq.0.03;0.005.ltoreq.w.ltoreq.0.08;with the proviso that 0.01.ltoreq.u+v+w.ltoreq.0.10; and 5.7.ltoreq.z.ltoreq.8.1 . The permanent magnets prepared with the alloy have very high magnetic properties, especially, in the coercive force and the maximum energy product even better than those obtained with a samarium-based alloy along with good machinability as in the cerium-based alloys suitable for mass production.

Abstract: Fine-grained sintered magnetic material having the composition expressed by SmMz where M is essentially cobalt or a combination of cobalt, iron and copper, exhibits a large coercive force critically when the z-value is in the vicinity of 8. As small amount of zinc can be added to the raw material to aid in the sintering of the material.

Abstract: Rare earth cobalt magnet materials, which comprised of cobalt, manganese, copper and 12 to 13 mole % of cerium and/or samarium are provided. These magnetic materials have improved magnetic characteristics, especially very high values of the maximum energy product.