JPS6031780B2 - Sealing glass - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sealing glass, particularly to a sealing glass used for sealing ferrite.

Mn-Zn ferrite (ferromagnetic material), which is hot-press molded after mixing and mixing oxides of Fe203, Mn02, and ZNO in a certain ratio, is used as a main component of various magnetic heads such as video recorders and recording machines. However, the sealing glass used for sealing the ferrite must fill the magnetic insulation part of the ferrite and have extremely high magnetic insulation properties. When sealing ferrite, in order to prevent cracks or fractures from occurring in the glass or ferrite during the cooling process, it goes without saying that the optimal thermal slope coefficient of the glass for sealing should be selected and the peeling speed should be carefully considered. That's true.

For example, during the slow cooling process, the temperature rises from the softening point (Ts) to the strain point (Sp) of the glass at a rate of 0.5 to 2°C/min, and the temporary strain that occurs during slow cooling must be removed. . In addition, in order to minimize the permanent strain that occurs below the seoing point, the thermal properties of the sealing glass must be a transition point (Tg) of 330 to 340°C and a softening point (Ts).
) 400℃ or less, coefficient of thermal expansion (QIO -3000) 9
The condition of 6 to 103×10-7 skin/arc/°C must be satisfied. Furthermore, since the ferrite insulating part has a complicated shape, it is important that the filled glass sufficiently wets the ferrite without forming voids, and that physical erosion does not occur at the interface. Furthermore, since water is used in the process of polishing the ferrite after sealing, the glass must also have water resistance and chemical resistance. The present invention applies Co to Pbo-ZNO-B2Q-based or POO-&03-based low melting point sealing glass.
By adding an appropriate amount of o, a sealing glass that satisfies the above conditions can be provided. That is, in weight percentage, Pb070~85%, &035~20%, Zn00
~12%, Si021~13%, R20ROO~5%
, A-2031 to 10%, and Coo 0.5-5%. Here, R20 represents an alkali metal oxide, and RO represents an alkali metal oxide. The composition of ordinary sealing glass with a low melting point is Pb0-Zn○-B203 system.
It is a type 3 glass, and contains additives such as Si02, A203, and alkali metal oxides.

The glass composition of the present invention satisfies the required thermal properties by using all or several of these components, and limits the range in which devitrification is low. Furthermore, this composition was obtained based on numerous experiments. The reason why the oxide composition constituting the glass of the present invention is limited to the above range is as follows.

Pbo is the main glass-forming oxide, but if the content exceeds 85%, the coefficient of thermal expansion will be too large for sealing Mn-Zn ferrite, resulting in large devitrification properties, and if it is less than 70%, high temperature viscosity will occur. The amount of gas also becomes high, and defoaming cannot be performed sufficiently.

When B203 exceeds 20%, the coefficient of thermal expansion becomes too low and becomes unsuitable for sealing ferrite, and when it is less than 5%, the softening point becomes high and degassing becomes difficult. Si02 is 13%
If it exceeds 1%, the high-temperature viscosity becomes high, and if it is less than 1%, devitrification becomes large and fluidity is lost during sealing. A203 contains Si02 to prevent devitrification when it exceeds 10%.
Combined with the addition of , the high-temperature viscosity becomes high and defoaming becomes difficult, and if it is less than 1%, the toughness of the glass decreases and cracks are likely to occur during processing.

If Coo exceeds 5%, devitrification becomes large and fluidity decreases, and if it is less than 0.5%, sufficient effects in water resistance, adhesive strength, and crack prevention cannot be obtained.

Zn○ can be added up to 12% to lower the softening point, improve water resistance, and lower the coefficient of thermal expansion.

If it exceeds 12%, devitrification becomes large and is not good.

Up to 5% of alkali metal oxides and alkali metal oxides may be added to adjust the thermal properties of the glass. Next, Examples of the present invention are shown in Tables 1 and 2.

Table 1 shows glass composition and thermal properties, and Table 2 shows properties such as Vickers hardness and water resistance. No. 1
~No. 5 is the glass of the present invention, and the gunwale. 6~M. 8 is Co
This is an example of glass that does not contain o. Note that the crack occurrence rate and crack occurrence rate in Table 2 are the results of a practical test of 50 to 100 pieces. Table 1 Table 2 The characteristics of the present invention are Pb○-ZnO-B203 system or P
By adding 0.5 to 5% Coo to the -B203 series glass, the mechanical strength increases, as is clear from the examples in the table, and the wetting property with ferrite and water resistance are significantly improved. It is permitted to do so.

As a result, the crack occurrence rate and fracture occurrence rate of the ferrite product are rapidly reduced, and the yield is improved. The addition of Cd○ has a slight effect on the Vickers hardness of the glass, but in terms of the wear resistance of ferrite heads and magnetic tapes, it is sufficient to meet the required characteristic values of glass of 300 to 500k9/grandson. There is no particular problem. These sealing glasses are extremely susceptible to devitrification, and if the composition of the glass slightly deviates, the devitrification often occurs immediately.

For example, it has been experimentally confirmed that glass containing 6% or more of COO exhibits devitrification and causes physical corrosion at the interface with ferrite. The devitrification test was confirmed by differential thermal analysis and holding at a temperature of 80020 for 2 hours. The wettability test was performed by placing a three-legged cube of glass on a ferrite plate and performing sealing heat treatment, and then measuring the wettability diameter in units of ribs.

If the wettability between glass and ferrite is poor, glass holes may occur at the interface, and Vo
ID and deteriorates magnetic insulation, making it unusable. For the water resistance test, 3 pieces of 20-30 mesh glass powder are placed in a Tough flask and boiled in 150 pieces of distilled water for 1 hour.

The amount of Pze+ ions eluted from the glass is analyzed in units of ppm using an atomic absorption spectrometer. Water resistance was significantly improved by adding the Coo component. Normally POO is 20~
The water resistance of borosilicate glass containing 30% is 20 to 3 PM, which is almost equivalent to this value. Recently, there have been many demands for a sealing glass with extremely good water resistance, and the present invention fully satisfies this demand.

Especially in the case of ferrite heads, if the glass is weak against the water and chemicals used during polishing, A reef grains (alundum type),
Abrasive materials such as C abrasive grains (silicon carbide-based) often bite into glass surfaces that have been corroded by water or chemicals, creating localized stress and causing glass cracks or breaks. These improvements in yield in the Examples shown in the table above demonstrate the effect of the present invention in overcoming the above-mentioned drawbacks. As described in detail above, the present invention applies Coo to the sealing glass at 0.5%.
By containing 5 to 5%, a sealing glass with significantly improved mechanical strength, wettability, and water resistance compared to conventional glass is obtained, which has extremely excellent practical effects. .

Claims (1)

[Claims] 1 PbO70-85% by weight percentage, B_2O_35
~20%, ZnO0~12%, SiO_21~13%,
R_2O+RO0-5%, Al_2O_31-10%,
A ferrite sealing glass having a composition of 0.5 to 5% CoO. However, R_2O represents an alkali metal oxide, and RO represents an alkaline earth metal oxide.