Abstract: A permanent magnet assembly for false tooth stabilization which includes a cup-shaped case formed of a corrosion resistant and magnetic material, an axially magnetized permanent magnet stored in the case, and a seal plate formed of a corrosion resistant material and fitted into and fixed to an end opening in the case to hermetically seal the case, the seal plate being composed of a central seal plate portion formed of a magnetic material to face the end face of the permanent magnet and a seal edge portion formed of a non-magnetic material to face in the region of the outer periphery of the permanent magnet. The width dimension of the seal edge portion is in the range of 0.03 to 0.07 mm, and at least the abutting portions of the case and seal plate are welded to each other.

Abstract: A floating type magnetic head is made of a polycrystalline material. A surface to be opposed to a magnetic recording medium is undulated with lands and grooves having a height difference of 50 to 200 .ANG. on an average and a repetition pitch of 5 to 20 microns on an average. The portions, in which the heights of the lands and the grooves abruptly change, extend along the boundaries of the polycrystals. The head surface opposed to the magnetic recording medium is sputter-etched to have the predetermined surface roughness.

Abstract: A floating type magnetic head is made of a polycrystalline material. A surface to be opposed to a magnetic recording medium is undulated with lands and grooves having a height different of 50 to 200 .ANG. on an average and a repetition pitch of 5 to 20 microns on an average. The portions, in which the heights of the lands and the grooves abruptly change, extend along the boundaries of the polycrystals. The head surface opposed to the magnetic recording medium is sputter-etched to have the predetermined surface roughness.

Abstract: A thin layer magnetic head comprising a ceramic substrate consisting essentially of 100 parts by weight of a ceramic material and 0.05 to 5 parts by weight of at least one compound from the group consisting of silicon oxide and iron oxide.

Abstract: A magnetic head assembly has, at least, a recording/reproducing magnetic head made of an Mn-Zn ferrite, a first reinforcer made of a non-magnetic ceramic material and bonded by a glass to the recording/reproducing magnetic head in parallel with the gap formed in the recording/reproducing magnetic head, erasing magnetic heads attached to both sides of the first reinforcer so as to limit the recording width of the recording/reproducing magnetic head, and second reinforcers made of a non-magnetic ceramic material and bonded in parallel to gaps in the erasing magnetic heads, the second reinforcers being positioned at both sides of said recording/reproducing magnetic head. The area Af defined by the thermal expansion coefficient curve of the Mn-Zn ferrite in the temperature range between the normal room temperature and the softening point of the bonding glass and the area Ac defined by the thermal expansion coefficient curve of the first reinforcer in the same temperature range satisfy the following condition:-3.

Abstract: Non-oxide powders such as carbides, nitrides, carbides/nitrides and borides are obtained by reducing an oxide powder in a reducing atmosphere, and after or concurrently with the reduction, treating the reduced powder in a carbonizing atmosphere, a nitrogenizing atmosphere, a carbonizing and nitrogenizing atmosphere, or a boronizing atmosphere. As the above oxide powder, there is used a brittle material obtained by rapid cooling of a melted oxide. The non-oxide powders obtained are utilized as a hard component of cemented carbides and cermet. These powders are fine particles having a particle size of 1.0 .mu.m or smaller and a high purity.

Abstract: A magnetic head device comprising a recording/playback magnetic head and erasing magnetic head, each of which consisting of cores made from a ferrite of Mn-Zn system and a reinforcement plate made from a non-magnetic ceramic material and bonded to respective cores; and sliders made from a non-magnetic ceramic material and united with the magnetic heads. The non-magnetic ceramic material for the sliders has a thermal expansion coefficient which is at least 5.times.10.sup.-7 /.degree.C. greater than that of the non-magnetic ceramic material for the reinforcement plate.