International Business Machines Corporation

Eugene B Rigby

William W Chow

Robert R Suchomel

Gerald A Daughenbaugh

Ralph W Scheidecker

A low magnetic isolation closure glass for use in multitrack magnetic tape heads has been prepared by combining a specific lead borosilicate glass with a specific borosilicate glass in a 60/40 weight percent ratio. The glass formed from the combination exhibits compatibility with ferrite and has reduced wear. Controlling the anneal temperature regulates the residual stress of the closure glass produced, and thus, provides some control over the wear characteristics of the glass.

Method of making low wear glass for magnetic heads

Process of hot isostatic pressing of MnZn ferrite material for producing ferrite close to theoretical density without a significant increase in grain size. Permeability is increased with the increase in theoretical density. The process includes the steps of pressurizing an entire ferrite sample which is surrounded by pieces of similar composition while in alumina crucibles with fused alumina grain there between and an optional oxygen getter on top of the grain, introducing an inert atmosphere, elevating pressure and temperature, the temperature elevated to a value below that previously used for sintering or hot pressing, and maintaining temperature to optimize density without excess grain growth. Density is thereby optimized without excess grain growth, while maintaining or improving the magnetic properties.

Process of hot isostatic pressing of ferrite material

In magnetic heads it is often necessary to place conductive films on a ferrite substrate. If the ferrite is conductive, an insulative film is required between the ferrite substrate and the conductive film. A thin insulative film can be formed on a surface of the ferrite substrate by alternately dipping the substrate in solutions containing particles of silica and alumina.

Method of making a thin film insulator

A bonding method which uses two solutions, one being anionic and the other being cationic, to lay down alternating layers of particles of accurate dimension onto members which are to be bonded. Thereafter, the layers are placed in contact, and the members are bonded together by diffusion bonding techniques.

Bonding method for producing very thin bond lines

A manufacturing process for making a finer ferrite powder which can then be used to make a very dense block of the ferrite ceramic. The process for making the powder includes the steps of co-precipitation of an aqueous solution of metal ions and an ammonium oxalate solution. The co-precipitation particles are separated, washed and dried. The particles are low-temperature calcined and then vibro-energy or ball milled and dried. The particles are fluffed and broken up in a blender and pressed into a mold for sintering and pressing in a hot isostatic press procedure. The ferrite blocks are then post annealed in an oxygen atmosphere and cooled to form a dense magnetic ceramic particle. Preferably the process is for use in the production of nickel-zinc ferrite used for magnetic heads.

Process for making fine magnetic ferrite powder and dense ferrite blocks

Diffusion bonding of dissimilar ceramics can be accomplished by the application of pressure only while the ceramics are at a temperature at which their expansion rates are the same. A process for manufacturing magnetic head cores is disclosed where a magnetic ferrite is diffusion bonded to a non-magnetic ceramic by heating the core pieces to the expansion rate crossover temperature and then applying the diffusion bonding pressure. The pressure is removed either before or after the bonded pieces are cooled.

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Tucson, AZ, United States of America

Eugene B Rigby