JPH0788233B2 - Graphite jig for glass molding - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a graphite jig for glass forming, and more specifically, various graphite jigs used for glass forming, for example, hermetic sealing, bottle making molds. The present invention relates to a liner, a glass lens mold, a glass melting carbon tank, a glass fusing jig, and the like. In particular, the present invention relates to a graphite jig that is extremely suitable for hermetic sealing used for hermetically sealing the lead wires of transistors and diodes and the terminals of devices with glass.

[Conventional technology]

At present, isotropic graphite is used as a jig for hermetic sealing, and this jig functions as a mold for positioning the lead wires of a transistor or a diode and sealing them with glass.

In other words, this jig is the contamination of transistors and diodes,
Used to hermetically seal leads and devices for the purpose of blocking moisture, the most general schematic is shown in FIG. For example, as shown in FIG. 1, a glass tablet (2) in which lead wire holes are bored, a shell ring (3) made of an iron alloy such as Kovar (Kovar (Fe-Ni-Co alloy)), and a lead wire (1). ) Is put into a graphite jig (4) and assembled, and this is heated to about 700 to 1000 ° C. in a nitrogen or nitrogen and hydrogen gas atmosphere to weld glass to the stem (s).
tem) is manufactured. There are various types of jigs for hermetic seals, from one hole for a diode to more than 10 lead wires for an IC.

However, when it is repeatedly used for the conventional hermetic sealing jig, there is a problem that the machining accuracy is deteriorated due to wear of pores due to insertion of lead wires and oxidation consumption of the jig itself. Further, as a result of abrasion of the pores and oxidative consumption, carbon powder is detached from the graphite jig and carbon powder adheres to the glass to contaminate the product, resulting in a problem that its performance is deteriorated.

Originally, the releasability between graphite and glass is generally good, but it cannot be said that it is sufficient for the purpose of hermetic sealing, and it is more resistant to oxidation, higher in strength, and higher in purity. Was requested.

The above-mentioned problems as the jig for the hermetic seal do not occur only in the jig for the hermetic seal,
It occurs widely in graphite jigs for glass molding, and similar problems occur in bottle liners for bottle making, graphite molds for glass lens molding, graphite tanks for glass melting, graphite jigs for glass melting, etc. .

[Problems to be solved by the invention]

The problem to be solved by the present invention is to solve the above-mentioned difficulties of the conventional graphite jig for glass molding of this kind, typically, the above-mentioned difficulties of the graphite jig for hermetic sealing, and more specifically, high strength. It is an object of the present invention to obtain a graphite jig for glass molding, for example, a jig for hermetic sealing, which is excellent in oxidation resistance and abrasion resistance, does not scatter fine carbon powder, and has better releasability from glass.

[Means for solving problems]

This problem is achieved by forming or (and) infiltrating a pyrolytic carbon (hereinafter referred to as PyC) coating on the surface or (and) inside of a conventional graphite jig of this kind. The present inventor has conducted extensive studies in order to solve the above-mentioned problems of a jig for glass molding of this kind using a conventional isotropic graphite, for example, a jig for hermetic sealing, and as a result, has 2 to 2 carbon atoms.
8 In particular, when a hydrocarbon gas having 3 carbon atoms (for example, C ₃ H ₈ ) or a hydrocarbon compound is pyrolyzed, PyC is infiltrated onto the substrate, and / or a film is formed on the surface, it should be of high purity. The inventors have found that a graphite jig of this kind can be manufactured that has high strength, excellent oxidation resistance, and excellent wear resistance, does not scatter carbon fine powder, and has better releasability from glass, and completed the present invention. That is, the present invention has a high-purity, glass-impervious, dense glass on or (and) inside the isotropic graphite substrate.
The present invention relates to a graphite jig for glass molding which has a PyC coating formed and / or impregnated with it.

[Operation and Configuration of Invention]

As a glass molding jig of the present invention, a hermetic sealing jig will be described below as a typical example for convenience of description.
However, it goes without saying that the present invention is not limited to this.

The hermetic sealing jig of the present invention is provided with Py on the substrate surface or (and) inside the conventional hermetic sealing jig.
Forming C to a film thickness of 5-250 μm or (and) 100 μm
It is formed by permeating m or more. And at this time PyC
The membrane needs to be particularly high in purity and impermeable and dense and strong. Here, impermeable means that the average pore radius measured by mercury porosimetry does not exceed 0.1 μm, and high purity means that the total ash content is 20 ppm or less.

In the present invention, the PyC film is required to satisfy both of the above requirements, and if any one of these requirements is not satisfied, the desired effect cannot be achieved sufficiently. The film thickness must be within the range of 5 to 250 μm.

In the Japanese Patent Application No. 60-98291 filed by the present inventor earlier, the coefficient of thermal expansion of the graphite base material is 0.5 × 10 ⁻⁶ / ° C. to 3.0 × 1.
0 ^-6 / ℃, the PyC coating film thickness of 20 ~ 250μm is preferred, but after further intensive research, as a result, the thermal expansion coefficient of the graphite substrate 3.0 × 10 ^-6 / ℃ ~ 6.0 × 10
^The inventors have found that it is possible to alleviate cracking or peeling of the PyC film under the thermal expansion of the PyC film coated with PyC and the graphite base material in the range of ^-6 / ℃. That is, the present invention provides improved slow conditions, i.e., relatively low temperature, low pressure, i.e., less than 1300 ° C and less than 50 Torr.
By generating PyC, it is possible to deeply impregnate PyC inside the graphite base material over a wide range of thermal expansion coefficient, and by forming a PyC coating on it,
The mechanical entanglement between the graphite base material and the PyC coating becomes stronger,
We have discovered a new fact that can suppress cracking and peeling of the PyC film due to the difference in thermal expansion between the graphite base material and the PyC film. Furthermore, by impregnating PyC into the inside of the graphite base material, the surface of the graphite base material becomes denser, and the mechanical strength and impact resistance are excellent, the wear of the graphite jig due to lead wire insertion is suppressed, and the oxidation resistance is further improved. It is also one of the major features of the jig for hermetic sealing in the present invention that the durability is significantly improved.

From the above, the range of the coefficient of thermal expansion of the graphite base material is 0.5 × 1
It is necessary to be 0 ^-6 / ° C to 6.0 × 10 ^-6 / ° C. It is generally accepted that the anisotropy gradually increases and the mechanical strength decreases as the thermal expansion coefficient of the base material decreases, and that the base material with a thermal expansion coefficient of less than 0.5 × 10 ^-6 / ° C is used for hermetic sealing. It is difficult to obtain the mechanical strength suitable for the jig. On the other hand, if the coefficient of thermal expansion becomes too large than 6.0 × 10 ^-6 / ° C, the graphite base material becomes dense, resulting in few graphite base material pores and Py.
The penetration of C becomes difficult, and the mechanical interlocking between the graphite base material and the coating described above becomes weaker accordingly, and cracks and cracks in the PyC film due to the difference in thermal expansion between the graphite base material and the PyC film during the heating-cooling cycle. There is a tendency that peeling occurs and the protective effect is reduced.

Impregnating a graphite substrate with PyC is a “graphite susceptor”
It is described in Japanese Patent Publication No. 47-1003, which is an invention related to the invention. In this invention, the temperature is 1100 to 1600 ° C and 0.5 to 1.2 mm.
The carbonaceous gas is thermally decomposed at a pressure of the carbonaceous gas of Hg, and then the carbonaceous gas is heated at a temperature 300 to 800 ° C. higher than the temperature and 0.5 to 1.0 mmHg higher than the carbonaceous gas pressure. A method is adopted in which the pyrolytic graphite is allowed to penetrate into the pores of the porous graphite body by decomposition. However, according to the research by the present inventor, it was found that the PyC film has a different thermal expansion coefficient when the production temperature is different. That is, during the so-called PyC impregnation step in the above patented invention, it is impossible to perform only the impregnation into the graphite base material, and the reaction involved in the PyC film formation is normally performed concurrently with the impregnation reaction. As a result, PyC films with different generation temperatures are stacked. Therefore, as described above, the PyC film cracks and peels due to the difference in thermal expansion between the PyC films. On the other hand, in the present invention, as a result of repeated studies in order to solve the problems such as cracking and peeling of the PyC film, by carrying out the reaction of impregnating PyC and forming a PyC film at the same production temperature, We have found the fact that the mechanical interlocking of the graphite substrate and the PyC coating can be strengthened. Further, the impregnation of PyC into the graphite base material is preferably 100 μm or more. If the amount is less than this, the strength of mechanical interlocking between the graphite base material and the PyC coating decreases. Regarding the PyC film thickness, the thermal expansion coefficient of the graphite base material is 0.5.
× 10 ^-6 /℃~3.0×10 ^-6 / ℃ is PyC thickness within the range of 5 to 25
It should be about 0 μm. If this film thickness becomes too large, rapid heating-cooling cycles tend to cause cracking or peeling, and the graphite base material may be exposed, resulting in an insufficient film forming effect. On the other hand, if the film thickness is too small, the intended effect due to the film formation is not sufficiently exerted. In the present invention, Py
When C is impregnated into the graphite base material, the properties such as abrasion resistance are further improved by the anchor effect. Therefore, by coating PyC to about 5 μm, it is equal to or more than the one with only 20 μm PyC coating formed. Exert the effect of. The coefficient of thermal expansion of the graphite base material is 3.0 × 10 ^{-6 /} ℃ ~ 6.0 × 1
Within a large range of 0 ⁻⁶ / ° C., the PyC film thickness needs to be 5 to 60 μm. Although impregnating PyC into the graphite base material improves the mechanical interlocking of the graphite base material and the PyC coating, if the PyC coating is performed in a range of more than 60 μm, the graphite base material becomes The difference in thermal expansion from the PyC coating tends to cause cracking and delamination of the PyC coating.

In summary, the thermal expansion coefficient of the graphite base material is 0.5 × 10 ^-6 / ℃ ~
Preferably in the range of 6.0 × 10 ^-6 / ℃, the thermal expansion coefficient of the PyC thickness particularly graphite substrate at that time, 0.5 × 10 ^-6 /℃~3.0×10 ^-6 /
Within the range of ℃, about 5 ~ 250μm, thermal expansion coefficient is 3.0 × 10
^In the range of ^-6 / ° C to 6.0 x 10 ^-6 / ° C, it is necessary to be about 5 to 60 µm.

In the present invention, when forming the PyC coating, it is preferable to selectively orient the graphite crystal basal plane, that is, the hexagonal carbon plane of the carbon, on the surface of the substrate. Such parallel orientation can further improve the oxidation resistance.
This specific orientation can be easily achieved by adjusting the temperature during PyC film formation, and can be achieved by setting the temperature to 1000 to 1300 ° C.

According to the research conducted by the present inventor, the following has been clarified. When the intensity of the (002) diffraction line is used as a measure of the degree of selective orientation, the results are shown in Table 1 below, and a thermogravimetric analyzer is used. Then, the oxidation onset temperature of the PyC film at each production temperature is measured and used as a guide for the oxidation resistance, as shown in Table 1 below.

From these results, Py with a low anisotropy and a low anisotropy was observed when the generation temperature was 1400-1600 ° C, the oxidation initiation temperature was low.
C film is formed, whereas 1000-1300 ℃ and 1700-250
At 0 ° C., it is found that the PyC film having a high oxidation start temperature, a high X-ray diffraction intensity and a large anisotropy is selectively oriented on the base material graphite. However, there was a drawback that diffusion and impregnation of PyC into the base material were not always good under the conditions of high temperature.

This tendency is slightly influenced by other conditions,
The above temperature range does not necessarily have to be strictly adjusted, and for example, the concentration range can be made slightly wider by appropriately selecting the concentration of the hydrocarbon gas used and the degree of pressure reduction. Further, in such a temperature range it is possible to further improve the oxidation resistance, especially in the field of use where the oxidation resistance is not strongly required,
It is not always necessary to set the temperature within the above range, and the wettability with glass and the releasability are excellent even at a temperature outside the above temperature range.

The PyC itself of the PyC coating formed in the present invention is well known in the art, and is produced by thermally decomposing a carbonaceous material such as a hydrocarbon gas such as C ₃ H ₈ or a hydrocarbon compound. It is also well known that it is a carbon that does.

In the present invention, the method itself for forming the PyC coating on the surface of the graphite base material is not limited in any way, and the method is not limited as long as the PyC coating having the above-mentioned predetermined requirements is formed. Any of the above forming methods can be effectively applied.

It should be noted that the graphite itself originally has a property that it does not wet the molten glass and does not easily adhere to it, but by further coating it with PyC, the strength is increased, it is less likely to break, and the durability is increased,
In addition to imparting the property of being difficult to be pulverized, it is possible to further improve the wettability with the glass and the releasability, conveniently as a glass molding material.

The wettability between the PyC-coated graphite and the glass and the releasability of the glass are shown below, when the present inventors actually show experimental results.

As a glass sample, glass for Kovar cut into cubes with dimensions of 5 × 5 × 5 mm was used, and the coefficient of thermal expansion conventionally used as a jig for hermetic sealing is 4.4 × 10 ^-6 / ° C.
For a graphite base material with a bulk specific gravity of 1.86 [-] and dimensions of 30 x 30 x ^t 3 mm
It was formed under the conditions of Example 1 described below at a temperature of 1000 to 2500 ° C.
Using PyC-coated graphite (thickness about 30 μm), place the above glass sample on it, and use an electric furnace in N ₂ gas atmosphere to
The temperature was raised to ℃ and held for 10 minutes. The maximum contact angle at that time was measured using an angle reader.

As a result, while the contact angle between graphite and glass used as a conventional hermetic sealing jig was about 110 ° C, the PyC-coated graphite according to the present invention had a contact angle of about 150 ° C regardless of the generation temperature. It can be seen that the contact angle of is and the performance is remarkably improved in terms of wettability with glass and releasability. Further, peeling after cooling could be performed without any trouble, and there was no damage due to the difference in expansion.

Further, in the present invention, by coating with PyC, the jig becomes impermeable to the glass, the molten glass penetrates into the graphite pores and adheres after cooling, making it difficult to remove or damage due to expansion difference. There are no drawbacks such as doing. It can be said that one of the features of the present invention is that the release property of the PyC-coated graphite material is improved and the impermeability is a property suitable as a jig material for glass molding.

Although the application as a jig for hermetic sealing has been mainly described above for convenience of description, it can be used for many applications as a glass forming jig or a matrix material by utilizing such properties of PyC-treated graphite. For example, a liner for bottle making molds, a mold for glass lenses (glasses, optical lenses, etc.), a carbon tank used when melting and mixing glass and metal, and further glass for metals (terminals, plates, etc.), ceramics. It is sufficiently effective for various purposes such as jigs used for fusing to etc.

〔Example〕

Next, the present invention will be described more specifically with reference to Examples.
The invention is not limited to these examples.

Example 1 The substrate characteristics for the graphite jig used were as follows.

Thermal (referred to as hereinafter CTE) expansion coefficient of ^{2.4 × 10 -6 /℃,5.5×10 -6 / ℃} ( room temperature to 400 ° C.), the bulk specific gravity 1.55 (CTE is 2.4 × 10 ^-6 / ℃ graphite), 1.85 (CTE is 5.5 × 10 ^-6 / ° C graphite) ・ Anisotropic ratio 1.02 ・ Ash content 20ppm or less ・ Dimensions 150 × 100 × ^t 20mm (Hole diameter φ1mm (× 100 pieces)) The above graphite jig to 1250 ° C Heat and add C ₃ H ₈ gas at 25 l / min
(STP) and H ₂ gas were flown at a flow rate of 60 l / min (STP), the furnace pressure was maintained at 30 Torr, PyC was impregnated into the graphite base material for about 120 μm, and a PyC coating film was formed as it was. The thickness of the coating varies according to the generation period and is shown in Table 2 (CTE is 2.4 × 10 ^-6 /
C. (for graphite jig), and Table 3 (for CTE 5.5.times.10.sup.- ⁶ / .degree. C. for graphite jig).

The PyC impregnation and coating were carried out by using the apparatus shown in FIG. 2 and setting this graphite jig on the sample mounting table (13) of the apparatus shown in FIG. The heating method was performed by resistance heating of a graphite heater (8), and C ₃ H ₈ gas and H ₂ gas were introduced from the bottom of the sample chamber through a gas introduction pipe (12) and discharged upward as shown in FIG. However, in FIG. 2, (5) is a vacuum container, (6) is a gas exhaust pipe, (7) is a heat insulating material, (8) is a graphite heater,
(9) is a graphite susceptor, (10) is a heat insulating material mounting base, (1
1) is a graphite support post, (12) is a gas inlet pipe, (1
3) is a sample mounting table, (14) is a sample, and (15) is a gas exhaust pipe.

Using various PyC coated graphite jigs obtained above,
The diode was glass-sealed in an N ₂ atmosphere. The life of the hermetic seal jig was determined by the number of times the contact portion when the lead wire was inserted was repeatedly worn by 0.1 mm.

Next, a rapid heating and cooling test was conducted, and PyC obtained in the same manner as above
The coated graphite jig was heated to 1500 ° C. for 5 minutes and then placed in water to examine the peeling state of the PyC coating. Five samples were used for each condition.

Further, at the same time as the above graphite jig, put a base graphite processed into a size of φ10 × 20 mm, coat PyC by the same method, measure the average pore radius by the mercury injection method, and evaluate the impermeability. .

The results are shown in Tables 2 and 3.

From Tables 2 and 3 above, the CTE of the graphite base material is 0.5 × 10 ^-6 / ° C.
Within the range of ~ 3.0 × 10 ^-6 / ℃, the thickness of PyC coating is 5
About ～250Myuemu, about 5~60μm within the scope of CTE is 3.0 × 10 ^-6 /℃~6.0×10 ^-6 / ℃ is not adhered carbon powder, excellent wear resistance, achieve the intended purpose It turns out that it is extremely effective in doing so.

Example 2 As shown in Table 4 below, a graphite base material having a predetermined CTE value was coated with 50 μm of PyC under the same conditions as in Example 1, and a rapid heating and quenching test was conducted.

From Table 4 below, no peeling or cracking occurs when coating PyC
It can be seen that it is possible to use a graphite substrate having a CTE in the range of ^{0.5 × 10 -6 /℃~6.0×10 -6 / ℃} .

From the above, a graphite jig for glass molding which is obtained by thermally decomposing a hydrocarbon gas such as C ₃ H ₈ gas or a hydrocarbon compound on the surface of and / or inside the isotropic graphite base material has high purity and carbon powder is glass. It can be said that it is a graphite jig that does not adhere to the surface and has excellent wear resistance and oxidation resistance and good releasability.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a jig for hermetic sealing, and FIG. 2 is a drawing showing an example of an apparatus used for manufacturing the jig of the present invention. 1 ... Lead wire 2 ... Glass tablet 3 ... Shell ring 4 ... Graphite jig 5 ... Vacuum container 6 ... Gas discharge pipe 7 ... Insulation material 8 ... Graphite heater 9 ... Graphite susceptor 10 ... Heat insulating material mounting table 11 …… Graphite support post 12 …… Gas inlet tube 13 …… Sample mounting table 14 …… Sample 15 …… Gas discharge tube

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication C03B 11/00 N C03C 27/02 Z C04B 35/52 41/87 H (56) References Sho 60-103087 (JP, A) JP 61-256993 (JP, A) JP-B 47-1003 (JP, B1)

Claims (4)

[Claims] 1. The average coefficient of thermal expansion from room temperature to 400 ° C. is 0.5.
On the surface of the isotropic graphite substrate of × 10 ^-6 / ° C. to 3.0 × 10 ^-6 / ° C., the total ash content is 20 ppm or less of high purity, and the average pore radius measured by mercury porosimetry is 0.1. A pyrolytic carbon having an impermeability not exceeding μm is coated with a thickness of 5 to 250 μm to form a film, and / or the pyrolytic carbon is 100 μm or more from the surface inside the isotropic graphite substrate. A graphite jig for glass molding that penetrates all the way. 2. The average coefficient of thermal expansion from room temperature to 400 ° C. is 3.0.
On the surface of the isotropic graphite substrate of × 10 ^-6 / ℃ ~ 6.0 × 10 ^-6 / ℃, the total ash content is 20ppm or less of high purity, and the average pore radius measured by mercury porosimetry is 0.1. Pyrolytic carbon having an impermeability not exceeding μm is coated to a thickness of 5 to 60 μm to form a film, and / or 100 μm from the surface of the isotropic graphite base material. Graphite jig for glass molding that is impregnated to the above. 3. The graphite jig for glass molding according to claim 1, wherein the graphite jig for glass molding is a jig for hermetic sealing. 4. The graphite jig for glass molding according to claim 2, wherein the graphite jig for glass molding is a jig for hermetic sealing.