JPH06316459A - Structural nonmagnetic ceramics material - Google Patents

Abstract

PURPOSE:To provide a structural nonmagnetic ceramics material having a high magnetic flux density, a coefft. of thermal expansion nearly equal to that of Mn-Zn ferrite, enhanced mechanical strength and workability by using a multiple oxide sintered compact consisting of NiO and ZnO as a base. CONSTITUTION:A mixture of 50-95mol% NiO with 50-5mol% ZnO is calcined, pulverized and granulated. The resulting granules are compacted and fired to obtain the objective nonmagnetic ceramics material made of a multiple oxide sintered compact consisting of NiO and ZnO and having 120X10<-7>-145X10<-7>/ deg.C coefft. of thermal expansion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structural non-magnetic ceramic material, and more particularly to a non-magnetic ceramic material useful as a material for sliders, spacers, substrates of magnetic heads.

[0002]

_2. Description of the Related Art Conventionally, as nonmagnetic materials for magnetic heads of this kind, CaO--TiO.sub.2 series, MnO--NiO series and MgO have been used.
-NiO ceramic material is used. The thermal expansion coefficient of each of these materials can be selected within the range of 100 to 120 × 10 ⁻⁷ / ° C. by appropriately adjusting the composition,
The Vickers hardness is moderate at 750 to 900 Hv, is dense, and has an advantage that a smooth polished surface can be obtained.

[0003]

However, in recent years,
The high magnetic flux density MnZn-based ferrite that has been adopted as a magnetic head material to improve recording density is
Since the coefficient of thermal expansion is as large as 130 to 145 × 10 ⁻⁷ / ° C., the conventional non-magnetic ceramic material has a problem that cracks occur in the manufacturing process of the magnetic head and deterioration of magnetic characteristics due to residual thermal stress. It became clear.

Therefore, it is an object of the present invention to obtain a structural non-magnetic ceramic material having a thermal expansion coefficient approximately equal to that of a high magnetic flux density MnZn type ferrite and excellent in mechanical strength and workability. Is.

[0005]

As a means for achieving the above object, the present invention provides a composite oxide sintered body composed of 50 to 95 mol% of NiO and the balance substantially ZnO as a main component of a nonmagnetic ceramic material for a structure. It is intended to be used as.

[0006]

The reason for limiting the composition of the complex oxide sintered body to the above range is as follows. When the content of NiO is less than 50 mol%, that is, when the content of ZnO is more than 50 mol%, the thermal expansion coefficient becomes smaller than 120 × 10 ⁻⁷ / ° C., and the content of Nio is more than 95 mol%, that is, the content of ZnO is 5 mol%. This is because if it is less than%, the workability decreases.

[0007]

Example As a raw material, commercially available reagent grade nickel oxide and zinc oxide were weighed and blended in the composition ratio shown in Table 1,
Wet mix using a ball mill and dry to 1000
It was calcined at ℃ for 2 hours. Each of the obtained calcined products was finely pulverized and granulated, and formed into a diameter of 10 mm and a thickness of 2 mm at a pressure of 1.0 t / cm ² , and then fired at 1300 to 1350 ° C. for 2 hours to obtain Ni.
A sample composed of a composite oxide of O and ZnO was obtained.

The thermal expansion coefficient, Vickers hardness, bending strength and workability of each sample were measured. The results are shown in Table 1. In addition, in Table 1, the workability indicates the amount of increase in power consumption of the spindle motor in units of W when processed by the same processing machine. Further, the samples marked with * in the numbers have compositions outside the scope of the present invention.

[0009]

[Table 1] Sample composition (mol%) Coefficient of thermal expansion Vickers hardness Flexural strength Workability No. NiO ZnO (× 10 ^-7 / ° C) (Hv) (kg / cm ² ) (W) * 1 20 80 86 756 1960 300 * 2 30 70 88 725 2020 290 * 3 40 60 95 732 2380 238 * 4 45 55 115 720 2370 210 5 5 50 50 122 717 2380 211 6 5 55 45 129 695 2360 217 2240 217 60 40 132 706 6260 2290 213 9 80 20 134 655 2200 222 10 90 10 138 661 2210 226 11 955 5 141 643 2150 235 * 12 98 2 145 550 1870 331

As is clear from the results shown in Table 1, the composite oxides of Sample Nos. 5 to 11, which are examples of the present invention, overlap with the high magnetic permeability MnZn ferrite 120 to.
It has a coefficient of thermal expansion in the range of 145 × 10 ⁻⁷ / ° C. and exhibits excellent mechanical strength and workability. On the other hand, as in the comparative examples shown in Sample Nos. 1 to 4, the coefficient of thermal expansion is 120 × 10 in the composite oxide having the molar percentage of NiO less than 50 mol%.
^-7 / ° C, which is smaller than the coefficient of thermal expansion of high-permeability MnZn ferrite, and when the content of Nio exceeds 95 mol% as in the comparative example shown in Sample No. 12, the coefficient of thermal expansion is 140 It is suitable to be × 10 ^-7 / ° C, but it is found that the mechanical strength and workability are poor.

[0011]

As described above, according to the present invention, the structural non-magnetic ceramic material is made of 50 to 95 mol% of NiO and ZnO.
Since the composite oxide sintered body composed of 5 to 50 mol% is the main component, it is excellent in mechanical strength and workability, and the thermal expansion coefficient can be controlled within the range of 120 to 145 × 10 ⁻⁷ / ° C. Therefore, even when a magnetic head is manufactured using high magnetic flux density MnZn ferrite, sliders, spacers,
It is possible to prevent cracks from being generated in the substrate and the like, and it is possible to reduce residual thermal stress, so that it is possible to prevent deterioration of the magnetic characteristics of the magnetic head.

Claims (1)

[Claims] 1. A structural non-magnetic ceramic material containing, as a main component, a composite oxide sintered body composed of 50 to 95 mol% of NiO and the balance substantially consisting of ZnO.