JPH0459264B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a non-magnetic ceramic material used in the construction of a magnetic head, and in particular to a non-magnetic ceramic substrate material for a thin-film magnetic head for depositing or sputtering a metal magnetic thin film. be. [Prior art] The magnetic head is a VTR (Video Tape Recorder),
Demand has been rapidly increasing in recent years as a core component of computers and audio equipment. As high-density recording in VTRs, computers, etc. continues to advance, research into thin-film magnetic heads made of thin films has recently been actively conducted as the next generation magnetic head. Thin film heads are composite heads in which recording and reproducing functions are provided by a metal magnetic thin film such as Permalloy (Fe-Ni) or Sendust (Fe-Al-Si), and a non-magnetic substrate is provided with sliding performance such as wear resistance. The substrate itself also requires important characteristics. Conventionally, barium titanate BaTiO ₃ and calcium titanate have been used as non-magnetic ceramic substrates of this type.
CaTiO ₃ , alumina/titanium carbide Al ₂ O ₃・T・C
Ceramic materials such as [Problems to be Solved by the Invention] However, ceramic substrates made of such materials have the following problems. In other words, during film formation such as evaporation and sputtering to bring out the characteristics of the metal magnetic thin film, and during subsequent heat treatment and glass bonding at the gap part, the thin film may peel off due to the difference in thermal expansion coefficient with the substrate as described later. There was a problem with that. Furthermore, the previously proposed ceramic substrates have a small thermal expansion coefficient of about 10×10 ^-6 /°C, and glass, whose thermal expansion coefficient matches that of a metal magnetic thin film, has low hardness and is not suitable for magnetic tapes. The disadvantage was that there was a large amount of wear during sliding. For this reason, there has been a strong demand for a non-magnetic substrate that has a thermal expansion coefficient of 12 to 15×10 ^-6 /° C. of a metal magnetic thin film such as permalloy, and has wear resistance comparable to that of ferrite. [Means for Solving the Problem] In view of the above, the present inventor has conducted extensive research and found that a TiO ₂ -NiO-CaO-MgO composite oxide with a specific composition meets the above objective. As a result of further research, it was discovered that more preferable wear resistance can be imparted by adding at least one of Al ₂ O ₃ , ZrO ₂ or Cr ₂ O ₃ , and the present invention has been completed. The non-magnetic substrate made of the ceramic substrate material for thin film heads of the present invention is characterized by 20-60% by weight of _TiO2 , 20-60% by weight of NiO, 10-40% by weight of at least one of CaO or MgO, and 10-40% by weight of at least one of CaO or MgO. ₂ O ₃ , ZrO ₂ or
At least one of Cr ₂ O ₃ is contained in an amount of 2.5 to 10% by weight, which increases the thermal expansion coefficient to 11 to 14×10 ^-6 /
The object of the present invention is to provide a material that has a wear resistance that almost matches that of a metal magnetic thin film in terms of temperature and has a wear resistance that is higher than that of ferrite. In the above range, if TiO ₂ is less than 20% by weight, the wear resistance will be poor, and if it is more than 60% by weight, the coefficient of thermal expansion will be small. Although NiO increases the coefficient of thermal expansion,
If it is less than 20% by weight, the coefficient of thermal expansion will be small, and if it is more than 60% by weight, the abrasion resistance will be poor. If the content of at least one of CaO or MgO is less than 10% by weight, the coefficient of thermal expansion will be small, and if it is more than 40% by weight, the wear resistance will decrease. The amount of at least one of Al ₂ O ₃ , ZrO ₂ or Cr ₂ O ₃ needs to be 2.5 to 10% by weight, and if it is more than this, the coefficient of thermal expansion will be small. [Example] An example of a method for manufacturing a ceramic substrate using the nonmagnetic ceramic material for a magnetic head of the present invention will be described. After thoroughly mixing a predetermined amount of titanium oxide, nickel oxide, calcium oxide, magnesium oxide, or a compound that can be converted into these oxides by firing using a mixer such as a ball mill, this mixture is heated at a temperature of 800 to 1200℃. Calculate. Next, Al ₂ O ₃ , ZrO ₂ , and Cr ₂ O ₃ powders are added to this calcined powder, mixed and ground again using a mixer such as a ball mill, and after drying, a press binder is mixed and molded.
Calcinate in air or nitrogen at a temperature range of 1250-1400°C. In this case, each raw material may be used as an independent powder, or any combination of calcined powders may be used. Furthermore, it may be used as a composite oxide or composite oxide powder prepared by known means such as a coprecipitation method or a colloid addition method. In the firing after molding, a high-density firing method such as a hot press method may be used in addition to the pressureless sintering method. Next, the present invention will be explained in more detail with reference to specific examples. The coefficient of thermal expansion was determined from the average linear expansion from room temperature to 500°C according to the JIS method. In addition, the wear resistance is
Using a disc type abrasion tester, load 50Kg/cm ² , circumferential speed
The test piece was operated for 100 hours at a speed of 150 cm/sec, and the change in length of the test piece was determined. The sample was used as the pin, and iron was used as the disk. Example: Varying the ratio of titanium oxide, nickel oxide, magnesium oxide and calcium carbonate, using a ball mill.
The mixture was wet mixed for 24 hours, dried, and then fired at 1000°C in the air to produce various calcined powders. Next, Al ₂ O ₃ , ZrO ₂ , and Cr ₂ O ₃ powders were added in various ratios to the various powders obtained, wet mixed in a ball mill for 24 hours, and after drying, the powders obtained as a press binder were mixed.
Add 1% by weight of PVA (polyvinyl alcohol),
Samples 1 to 20 shown in Table 1 were prepared by molding at 2 tons/cm ² and firing in the air at 1300° C. for 1 hour.

【table】

〔effect〕

According to the present invention, it is possible to obtain a non-magnetic ceramic substrate suitable for a thin film head, which has a coefficient of thermal expansion that almost matches that of a metal magnetic thin film and has a small amount of wear. It should be noted that the ceramic material of the present invention is not limited to the thin film head described above, but can naturally be used as a non-magnetic ceramic material for other magnetic heads to which such performance can be applied.

Claims (1)

[Claims] 1 TiO ₂ 20 to 60% by weight, NiO 20 to 60% by weight,
At least one of CaO or MgO is 10 to 40% by weight
and at least one of Al ₂ O ₃ , ZrO ₂ or Cr ₂ O ₃
A non-magnetic ceramic material for a magnetic head, characterized by comprising 2.5 to 10% by weight. 2. The ceramic material for a magnetic head according to claim 1, which has a coefficient of thermal expansion of 11 to 14×10 ^-6 /°C.