Abstract: A grooved magnetic substrate for thin film magnetic heads having grooves filled with glass having substantially no pores therein and an interdiffusion layer between substrate and glass of 5 microns or less. The substrate is produced by hot-filling the groove with glass at a viscosity of 10.sup.6 -10.sup.8 poise and subjecting the substrate to hot isostatic pressure at 10.sup.6 poise or higher to define a definite apex point to define the gap depth.

Abstract: A flatness measuring apparatus which optically measures the flatness of an object, such as a slider surface of a magnetic head at a magnetic tape recording apparatus, required to have the flatness of hyperfine accuracy of 0.05 .mu.m or less. The flatness measuring apparatus is so constructed that interference fringes related to the plane of the object and a reference plane are produced and caught by a one-dimensional image sensor and that an optical element disposed between the image sensor and an interference fringe producing means is turned to change the visual field in the extending direction of the interference fringe, and is provided with a unit for measuring the flatness in connection with the turning position information of the optical element and an output of the image sensor, so that the error factor, such as the ununiformness in the characteristic of each bit at the image sensor or disorder with the lapse of time in the optical system, can be eliminated to thereby gain the measurement accuracy of 0.

Abstract: A composite substrate for a thin-film magnetic head comprises a substrate material, and an insulating oxide film formed thereon, and defining a smooth and stress-free surface having a surface roughness not greater than 50 .ANG.. A film of a magnetic material having improved magnetic properties may be formed on the surface of the oxide film.

Abstract: An alumina base substrate material for recording heads, which comprises a densely sintered body consisting essentially of:per 100 parts by weight of a base component of 30 to 40% by weight of a titanium compound having TiO.sub.2 to (TiC+TiO.sub.2) percentage of 5 to 15% by weight and the balance being Al.sub.2 O.sub.3,components A, B and C, provided that the A to B ratio is within a hatched KLMN area in FIG. 1, in the following given parts by weight, andoxidic impurities in amounts of no higher than 0.2% by weight based on the total composition,said sintered body having an average crystal grain size of no higher than 1.3 microns, a porosity per area of no higher than 0.5%, a bending strength of at least 70 kg/cm.sup.2 and a hardness H.sub.R A of at least 93.0: whereincomponent A is at least one of spinels expressed by RO-Al.sub.2 O.sub.3, where R is at least one of Mg, Mn, Ni and Co, in an amount of 2.0 to 17.5 parts by weight,component B is 0.2 to 2.0 parts by weight of ZrO.sub.2, andComponent C is 0.

Abstract: Aluminum oxide substrate material for magnetic heads having improved toughness consisting essentially of: (1) 100 parts by weight, consisting of aluminum oxide and 30 to 50 parts by weight of (TiC+TiO.sub.2), and that provided TiO.sub.2 /(TiC+TiO.sub.2).times.100=5 to 15, (2) 0.5 to 5 parts by weight of addition of free cutting comprising at least one from the group of MgO, NiO, Cr.sub.2 O.sub.3 and ZrO.sub.2, and (3) 0.05 to 2 parts by weight of Y.sub.2 O.sub.3.The method of hot-forming aluminum oxide substrate material for magnetic head having improved sinterability consisting of (a) preparing a green compact by molding a raw material mixture which contains: (1) 100 parts by weight, consisting of aluminum oxide and 30 to 50 percent by weight of (TiC+TiO.sub.2), and that provided TiO.sub.2 /(TiC+TiO.sub.2).times.100=5 to 15, (2) 0.5 to 5 parts by weight of machinability agents comprising at least one from the group of MgO, NiO, Cr.sub.2 O.sub.3 and ZrO.sub.2, and (3) 0.05 to 2 parts by weight of Y.sub.2 O.

Abstract: Magnetic head slider material consisting of 5.about.10 percent by weight of silicon, 1.3.about.7.8 percent by weight of tungsten silicide and essentially balanced silicon carbide. And it is method for producing said magnetic head slider material that at the time of which the mixed powder consisting of silicon carbide, carbon and tungsten is sintered, cellulose is also mixed with said mixed powder and sintered together at the same time. And then fibrous micropores are caused to the sintered body by the above-described sintering, after that molten metallic silicon infiltrated into fibrous micropores.

Abstract: A material for magnetic head sliders comprises a mixed powder consisting of 40 to 80% by weight of Al.sub.2 O.sub.3 and 20 to 60% by weight of TiO.sub.2, and further contains, per 100 parts by weight of the Al.sub.2 O.sub.3 and TiO.sub.2 mixture, 0.5 to 5 parts by weight of at least one of CaO, MgO and Y.sub.2 O.sub.3, and 0.5 to 10 parts by weight of ZrO.sub.2.