JPS6163542A - Crystallized glass having high thermal expansion coefficient and its preparation - Google Patents

Abstract

PURPOSE:To obtain a crystallized glass having high thermal expansion coefficient and suitable for chemical milling, etc., by melting and forming a glass raw material containing nucleation substance, and carrying out the thermal treatment and crystallization under controlled exposure to ultraviolet radiation at a specific temperature range. CONSTITUTION:100pts. of a base glass containing 76-84(wt)% SiO2, 1-7% Al2O3, 8-13% Li2O, 0-3% Na2O, 0-6% K2O, O-5% MgO, CaO, SrO, BaO, ZnO and/or PbO, and 0-3% B2O3 is added with 0.003-0.05% CeO2, 0.005-0.03% Au, 0.001-0.20% Ag, 0-0.5% Sb2O3, etc. The glass having the above composi tion is formed by melting, exposed to a controlled dose of ultraviolet radiation, and heat-treated at 780-840 deg.C. Fine crystals of lithium metasilicate, lithium disilicate and alpha-quartz are precipitated in the glass by this process. A crystal lized glass having a thermal expansion coefficient adjustable arbitrary within 110X10<-7>-145X10<-7>/ deg.C can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a crystallized glass having a large coefficient of thermal expansion, such as a substrate material for a magnetic head, and a method for producing the same.

[Prior Art] In magnetic recording devices such as VTRs and computers, advances are being made to increase recording density and accuracy, and to reduce device size and cost. Efforts are being made to introduce new materials and manufacturing methods.

So far, machined soft ferrite heads have been used for magnetic heads used for writing and reading magnetic recording tapes and disks.

However, soft ferrite heads have problems such as a high saturation magnetic density, a sharp drop in magnetic permeability in the high frequency range of 10M l-1z or more, and an inability to process track widths that are becoming narrower with high-density recording. Therefore, thin film magnetic heads are being actively developed which are manufactured by vapor deposition or sputtering of sendust, permalloy, amorphous metal, etc. on a non-magnetic substrate using a method similar to that used for manufacturing ICs.

Candidates for this substrate material include ceramics made by sintering powder and crystallized glass made by depositing crystals in glass. With these materials, if the difference in thermal expansion coefficient between the magnetic 7ig film and the substrate is large, the substrate may crack or the magnetic aj! Even if it is small, it may peel or break, causing warping, so matching the thermal expansion coefficient of the substrate and the magnetic thin film is an important property required for the substrate. However, for ceramic substrates, the thermal expansion coefficient of the magnetic thin film A two-substrate material with matching high thermal expansion has not yet been obtained. Additionally, the substrate is required to have no pores and to be able to obtain good flatness and surface roughness by polishing, but it is difficult to obtain a ceramic made by sintering powder that is completely free of pores. Moreover, in order to obtain a flat surface with low surface roughness, the particle size of the powder must be fine and uniform, making it very expensive.

On the other hand, crystallized glass is produced by melting the required glass components.
After molding, heat treatment is performed at an appropriate upper bound speed to form crystal nuclei, −
Next, it is made by sequentially growing secondary crystals and depositing microcrystals over the entire glass, so it is easy to obtain a porosity-free and well-polished surface. Regarding the technology for refining precipitated crystals in crystallized glass, please refer to T! It is already known that ZrO2 and ZrO2 can be used as nuclei for crystal formation of oxides, fluorides, metal colloids, and the like. Furthermore, Lfzo-A
ff20y S io2 type glass containing photosensitive silver chloride and cerium oxide as a sensitizing agent produces a latent image in the irradiated area when exposed to ultraviolet rays, and when this is heat-treated, silver colloid is generated, and furthermore, at high temperatures, Li2O・SiO2 crystals precipitate. The dissolution rate of these crystals in hydrofluoric acid is several tens of times faster than that of the glass portion, so only the precipitated portion can be dissolved away.
This allows images to be transferred optically and precisely cut, so it is used in wire guides for dot printers, heads for inkjet printers, etc. This method of manufacturing glass for chemical cutting is known, for example, from Japanese Patent Publication No. 32-50.
It is described in Publication No. 80. In other words, Special Public Interest Publications 1973-5
Publication No. 080 states that (1) lithium disilicate, (2 beta!!1) lithium disilicate, (2 beta!!1) %pyroxene,
(3) beta quartz, (4) crystalline solid solution of beta pyroxene and quartz, (5) lithium disilicate and beta pyroxene,
(61 Lithium disilicate and beta quartz, (7) Sodium disilicate and a crystalline solid solution of beta silicate and quartz,
Disclosed is a method for producing ceramic-like ceramic articles having high mechanical strength by heating for a sufficient period of time to form microcrystals such as porcelain.

[Problems to be Solved by the Invention] Although the above-mentioned Japanese Patent Publication No. 32-5080 obtains crystallized glass with high mechanical strength, the crystallization heat treatment essentially converts crystalline lithium metasilicate into crystals. This is done to change the glass matrix into crystalline lithium disilicate, and to change the glass matrix into crystallinity, and the precipitated crystals are thought to be limited from the viewpoint of mechanical strength, and are rather metastatic. Lithium silicate crystals are excluded. Also, the crystallization temperature is 890
℃, but in crystallized glass heat-treated at such a high temperature, crystal coexistence of meta, lithium silicate, and α-quartz can no longer occur, and therefore the thermal expansion coefficient is 110X.
It would be less than 10-1/'C. Although there are no detailed descriptions of the ultraviolet exposure conditions, there are usually many exposure steps to make the precipitated crystals fine and to obtain high strength, and the crystallized glass exposed under these conditions is similar to the heat treatment temperature mentioned above. Since the coexistence of three crystals becomes difficult to occur, the coefficient of thermal expansion becomes 110×10'/'C or less.

In view of the above points, the present invention provides a crystallized glass suitable as a chemical cutting glass such as a substrate material for a thin film magnetic head, particularly a crystallized glass having a coefficient of thermal expansion of 110 to 145X 1o-7/'C. The object of the present invention is to provide a method for easily manufacturing the crystallized glass.

Means for Solving Problem L] Achieving the above objective means having the following elements. In other words, a. It must be a non-magnetic material.

The coefficient of thermal expansion should match well with the magnetic thin film, and no warping will occur after the film is attached.

C. It must be compatible with magnetic thin films and have sufficient adhesion resistance.

D. There should be no reaction with the magnetic a film.

Ho, there are no pores.

To1: High strength.

and wear resistance equivalent to that of magnetic materials.

H. Good flatness and surface roughness can be obtained.

- Chipping is less likely to occur during the cutting process.

etc. is to be satisfied.

In order to achieve the above object, this invention finds that crystallized glass is most suitable, and that the coefficient of thermal expansion is improved by heat-treating and crystallizing glass made by melting and forming a glass raw material containing a crystal nucleus substance in a specific temperature range. This was completed after discovering that the thermal expansion coefficient becomes abnormally large and that this coefficient of thermal expansion also changes depending on the exposure R of ultraviolet rays. That is, in weight a%,
5i0276~84%, Al12031~7%, Li0
28-13%, Na2O 0-3%, K2O 0-6%
, MOOCaOlSrO, Bad, ZnO and PbO or a total amount of 0 to 5%, B2O: 10 to 3%.
~0.05%, A U 0.0005-0.03% and/or Ag 0.001-0.20% and 5
The main crystals precipitated in the crystallized glass produced by heat-treating the glass with 0.5% b2030 to precipitate microcrystals in the glass are lithium metasilicate, lithium disilicate, and α-quartz, and their thermal expansion The coefficient is 110X 10 /'C
The present invention relates to a crystallized glass characterized in that the temperature is 148×10 −7 /”C.

Furthermore, the coefficient of thermal expansion of this crystallized glass is adjusted by adjusting the amount of ultraviolet rays exposed to the glass and by adjusting the temperature range of 780 to 840'' in which lithium metasilicate crystals precipitated at a temperature higher than the transition point of the glass change to lithium disilicate crystals during heating. The present invention relates to a method for producing crystallized glass having a large coefficient of thermal expansion, which is carried out by adjusting the crystallization temperature between C and C.

Next, the reasons for the limitations of the present invention will be described.

The glass according to the invention is a so-called photosensitive glass for chemical cutting and is a lithium lithium silicate glass containing CeO2 as a sensitizer and AU and/or Ag as a nucleating agent. CeO2 is 0.003%
Below, the sensitizing effect is poor, and above o, osx, the sensitivity is poor. In addition, the nucleating agents AU and Ag should be added alone or together; if the nucleating agent is less than 5% of Au, O, 00, or less than 1% of O, oo, nucleation will be insufficient; u 0.03X, A go,
Addition of more than 20% of the Hakarasuni solution is wasteful as it will not be incorporated.

The substrate glass has a composition that facilitates the formation of crystals of lithium metasilicate, lithium disilicate, and α-quartz.
i0276% or less, L! At 0213% or more, the number of precipitation stages of α-quartz, which has a large effect of increasing the thermal expansion coefficient, decreases, making it impossible to obtain a thermal expansion coefficient of 110X 10-7/'C or more. As crystals G) become too small, it becomes difficult to melt the glass.

Further, Al1203 is added in an amount of 1% or more to improve the chemical durability of the glass, but if it is more than 7%, beta-vopyroxene crystals will precipitate, reducing the coefficient of thermal expansion. Na2O and 20 are added because they improve the melting properties of the glass, and 20 promotes the precipitation of lithium metasilicate crystals.
If it is 6% or more, crystals will be difficult to precipitate.

MQO, caolSrO, Bad, ZnO and PbO
The divalent metal oxide has the effect of preventing the precipitation of cristobalite crystals that cause a relatively noticeable bend in the thermal expansion curve around 200°C, so it may be added, but if it exceeds 5%, it will be difficult for the crystals to precipitate, resulting in acid resistance. degrade sexuality. B203 is effective in improving the meltability of glass, but if it exceeds 3%, it prevents crystal precipitation. 5b201 is 111 when melting glass
2. It is added as a foaming agent, but preferably 0.5% or less.

The coefficient of thermal expansion of glass before crystallization is 80-90X 10'
/'C, and the thermal expansion coefficient of crystallized glass in which only lithium metasilicate crystals are precipitated is equivalent to that of glass.

In the crystallized glass heat-treated at a temperature higher than the crystallization temperature of the present invention, the main crystals become lithium disilicate, and the coefficient of thermal expansion is 10.
It will be around 0X 10'/'C. Therefore, 110
Crystallized glass with a large coefficient of thermal expansion of ~145X 10'/'C varies somewhat depending on the glass composition, but it crystallizes in the temperature range where lithium metasilicate crystals change to lithium disilicate crystals, that is, at temperatures from 780°C to 840°C. became
It is obtained when the precipitated main crystals are lithium metasilicate, lithium disilicate, and α-quartz.

Regarding the exposure speed of ultraviolet rays, the sensitivity wavelength of glass is approximately 25
Since the range is 0 to 400 nl and the spectral energy distribution differs depending on the light source, it cannot be strictly limited, but if the amount of light emitted is lower than the normal amount of light emitted to promote the precipitation of sodium disilicate crystals. Crystallized glass with a large coefficient of thermal expansion can be obtained.

[Example] Glass having the following composition was melt-molded, exposed to ultraviolet light, and then heat treated. The results are shown in the table. (Margin below) The exposure time in the table is a parallel beam of irradiance of 76 mw/cm2 (measured by Dobcon ultraviolet intensity meter) obtained by passing 600w This shows the total time for equal exposure from both sides. Further, in the heat treatment, the heating rate is preferably 300° C./hour or less in order to ensure sufficient nucleation, but in this example, the heating rate is 100° C./hour. A suitable holding time is 1 to 3 hours in order to sufficiently precipitate crystals. The cooling rate is not particularly limited as long as it does not cause cracking, but in this example, the power was cut off and the material was left to cool in the furnace. Thermal expansion coefficient is measured and calculated by differential thermal dilatometer from 100 to 300℃
The average coefficient of thermal expansion between

Example No. 095 is due to the exposure time being too long, and
Samples No. 0 and No. 17 show examples in which the crystallization temperature is too high, so that the coefficient of thermal expansion is 110X 10-7/'C.

In addition to using chloroauric acid as a raw material for gold and silver chloride and silver nitrate as raw materials for silver, the glass according to the present invention uses oxides, carbonates, nitrates, and hydroxides as raw materials for ordinary optical glasses. 1,400 to 150 in a platinum crucible using
After polishing the glass that was melted at a temperature of 0℃ and slowly cooled,
It is obtained by exposure to light under predetermined conditions, heat treatment, and crystallization.

[Effects of the Invention 1] The crystallized glass of the present invention has a coefficient of thermal expansion close to that of magnetic materials such as cement and amorphous metals. Crystallized glass that matches the expansion coefficient can be easily manufactured.

Furthermore, in the crystallized glass of the present invention, the precipitated crystals are made fine by nucleation, so the polished surface has very good flatness and surface roughness, and the strength is about three times that of glass, and it has a hard surface. Since it is similar to the above-mentioned magnetic materials, it is suitable as a substrate material for magnetic heads and magnetic disks. Moreover, since it also has properties as a photosensitive glass for chemical cutting, chemical cutting processes such as holes and grooves can be applied to the glass according to mask patterns, and it can also be used for microfabrication of magnetic heads.

BRIEF DESCRIPTION OF THE DRAWINGS The drawing shows thermal expansion curves of the crystallized glasses shown in Examples Nos. 16 and 17. Applicant Hoya Glass Co., Ltd. Agent Masayuki Asako Temperature (°C)

Claims (1)

[Claims] 1 SiO_2 76-84% by weight percentage, Al_2
O_3 1-7%, Li_2O 8-13%, Na_2
O 0-3%, K_2O 0-6%, MgO, CaO,
CeO_2 0.003-0.0 per 100 parts by weight of base glass consisting of one or a total of 0-5% of SrO, BaO, ZnO and PbO, and 0-3% B_2O_3
5%, Au 0.0005-0.03% and/or Ag 0.001-0.20%, Sb_2O_3 0-
0.5%, the main crystals are lithium metasilicate, lithium disilicate, and α-quartz, and the coefficient of thermal expansion is 110.
A crystallized glass characterized in that the temperature is from ×10^-^7/°C to 145 × 10/°C. 2 SiO_2 76-84% by weight percentage, Al_2
O_3 1-7%, Li_2O 8-13%, Na_2
O 0-3%, K_2O 0-6%, MgO, CaO,
CeO_2 0.003-0.0 per 100 parts by weight of a base glass consisting of one of SrO, BaO, ZnO and PbO or a content of 0-5% and B_2O_3 0-3%
5%, Au0.0005-0.03% and/or A
g 0.001-0.20%, Sb_2O_3 0-0
．． After melting and forming glass with 5% added, it is exposed to ultraviolet rays and heat treated to precipitate microcrystals of lithium metasilicate, lithium disilicate and α-quartz in the glass. Thermal expansion characterized by adjusting the crystallization temperature between 110 x 10^-^7/°C and 145 x 10^-^7/°C by adjusting the crystallization temperature between 110 x 10^-^7/°C and 145 x 10^-^7/°C. A method for producing crystallized glass with a large coefficient.