JPH0477372B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a substrate material for a magnetic head incorporated in a floppy disk device or a hard disk device which is a peripheral device of a computer, and particularly to a nonmagnetic substrate material for a thin film magnetic head. [Prior Art] Generally, magnetic heads for computers, VTRs, or audio devices are constructed by glass-bonding ferrite, which is a magnetic material, and ceramic, which is a non-magnetic material. On the other hand, in the case of a thin film magnetic head, a magnetic thin film such as sendust or permalloy is formed on a magnetic or non-magnetic ceramic substrate by plating, vapor deposition or sputtering. Generally, Al ₂ O ₃ (alumina)-TiC (titanium carbide) ceramics are used as the substrate material for thin film magnetic heads. The reason for this is that it has an extremely high Vickers hardness of 2000 or more compared to other materials, so it exhibits high durability against starting and stopping due to contact with magnetic recording media. [Problems to be solved by the invention] On the other hand, the disadvantages are that the sinterability is poor;
To obtain a dense product, set the sintering temperature to 1850-1900.
℃, it is difficult to meet the demand for miniaturization due to poor machinability, and the magnetic layer cannot be formed directly on the substrate due to its low resistivity, making it difficult to connect the substrate and the magnetic layer. between Al ₂ O ₃
For example, it is necessary to form an insulating layer such as Among these, in particular, if the value of specific resistance can be improved, the thickness of the insulating layer formed on the substrate can be reduced, and the time required for manufacturing the head can be shortened. [Means for Solving the Problems] As a result of research based on the above-mentioned problems and points of view, the present invention has developed an additive that promotes sintering, an additive that shows a grain growth matching effect, and an additive that improves resistivity. It is possible to obtain a good substrate material for a thin film magnetic head by simultaneously adding additives for the magnetic head. Specifically, as a result of various experiments, the present invention found that lanthanide oxide was added to 100 wt% of the main component consisting of 15 to 60 wt% TiC and the balance Al ₂ O ₃ .
Adding ~10wt% improves the wettability between Al ₂ O ₃ and TiC, improving sinterability, and
By adding 1 to 5 wt% of one or more additives that exhibit a grain growth matching effect such as Cr ₂ O ₃ , TiO ₂ , Y ₂ O ₃ , and MgO, the processability is improved as a small grain size structure, and Si ₃ N _Four
TiC, which is the cause of low resistivity by adding
By reacting the free carbon inside with the Si contained in Si ₃ N ₄ to form high-resistance SiC, the resistivity is increased, and it has excellent machinability and the resistivity value is lower than that of conventional SiC. We were able to produce a high-density Al ₂ O ₃ --TiC ceramic substrate material for thin-film magnetic heads that is one order of magnitude higher than the standard. [Example] Hereinafter, the present invention will be described in detail according to Examples. Al ₂ O ₃ with an average particle size of 0.1 to 0.5 μm and a purity of 99% or more,
TiC, La ₂ O ₃ , CeO ₂ , Sm ₂ O ₃ , Cr ₂ O ₃ , TiO ₂ ,
Powder raw materials of Y ₂ O ₃ , MgO, and Si ₃ N ₄ were weighed so as to have the composition ratios shown in Table 1, and samples Nos. 1 to 20 were prepared. Note that the main component A indicates the respective wt% of TiC and Al ₂ O ₃ when the total of TiC and Al ₂ O ₃ is 100 wt%. Also. La ₂ O ₃ , CeO ₂ , Sm ₂ O ₃ (additive B),
Cr ₂ O ₃ , TiO ₂ , Y ₂ O ₃ , MgO (Additive C), Si ₃ N ₄
All of the weighed values of (additive D) are the proportions of Al ₂ O ₃ and TiC to the main component, which is 100 wt%. Samples No. 8 to 20 are for comparison.

[Table] After each sample was weighed as described above, it was mixed in a ball mill for 20 to 40 hours using ethanol as a solvent. After filtering and drying this, an organic binder was added and pressure molded into a block of 30 x 30 x 10 mm. Next, sintering was carried out at a temperature of 1750°C for 2 hours. The atmosphere during sintering was a 9 kg/m ² N ₂ atmosphere to prevent the added Si ₃ N ₄ from decomposing. Furthermore, after sintering, _N2 gas was used as a pressure medium, and the pressure was increased to 1000.
Kg/cm ² , temperature 1650℃, holding time 2 hours
Performed HIP processing. To evaluate the material properties of the sample obtained through the above steps, relative density, Vickers hardness Hv, bending strength F, and specific resistance were measured. In addition, after cutting out a 5 x 5 x 20 mm prism from each sample, the two adjacent 5 x 20 mm sides of the prism were mirror-finished, and the number of chips larger than 2 x 2 μm that occurred on the ridges was measured at a magnification of 1000x. 1 by counting using an optical microscope with
It was converted to the incidence rate per cm and was used as an evaluation item for processability. In addition, the size of chipping is 2 depending on its length.
It was classified into ~10 μm, 11-50 μm, and 51 μm or more. The above results are shown in Table 2.

〔Effect of the invention〕

As is clear from the above results, according to the present invention,
It is dense and has excellent machinability, and the resistivity value is lower than that of conventional
High-density Al ₂ O ₃ − for thin film magnetic heads exhibiting a level of 10 ^-1 Ω·cm, which is one order of magnitude higher than the level of 10 ^-2 Ω·cm.
TiC ceramic substrates can be easily manufactured.

Claims (1)

[Claims] 1 For 100 parts by weight of the main component containing 15 to 60 wt% TiC and the balance Al ₂ O ₃ , 1 to 10 wt % of at least one of La ₂ O ₃ , CeO ₂ , Sm ₂ O ₃ , Cr ₂ O ₃ , TiO ₂ ,
A substrate material for a thin film magnetic head, characterized in that 1 to 5 wt% of at least one of Y ₂ O ₃ and MgO and 1 to 10 wt % of Si ₃ N ₄ are added simultaneously.