JPH066492B2 - Method for manufacturing sintered body of fluorine phlogopite mica ceramics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to glass ceramics containing dispersed mica fine crystals in a glassy matrix.

[Conventional technology]

Glass ceramics containing mica fine crystals dispersed in a glassy matrix has excellent dielectric properties, thermal shock resistance, and good machinability, and is regarded as a promising material for expanding the application of fine ceramics. Glass ceramics containing fluorine phlogopite microcrystals dispersed therein are excellent in high temperature stability and are good materials.

As a method for producing such glass ceramics, a powder mixture of raw material components is prepared so that the final product has a composition suitable for forming and containing a necessary amount of fluorine phlogopite microcrystals. It is heated to a high temperature and melted to form a glassy matrix, which is once cooled and at the same time solidified into the desired shape of the final product, then 750 again.
A method is known in which a desired product is obtained by performing a heat treatment at a high temperature of -1100 ° C for a long time (for example, Japanese Patent Publication No. 54-34775).
In this method, it is necessary to heat to a high temperature of at least around 1400 ° C in order to obtain a homogeneous amorphous matrix by melting, but this increases the reactivity of the material itself containing a large amount of fluorine. The wear of the container is remarkable.
Also, when the melt is poured into a desired mold and solidified, in the case of a molded body having a large size, it is unavoidable that the temperature difference between the surface portion and the inside of the molded body becomes large during cooling. Will be non-uniform, and the final product after heat treatment will also be non-uniform. Therefore, it is difficult to obtain a good product having a large size. Further, since heating and melting at around 1400 ° C., cooling and solidification, and reheat treatment at 750-1100 ° C. are performed, there is a drawback that the heat energy cost is further increased.

Another manufacturing method is a method in which a fine powder of fluorine phlogopite crystals is sintered together with a binder having a lower melting point such as glass, phosphate, or low melting point mica to obtain the glass ceramics. In this method, one of the drawbacks of the above method, which is high in thermal energy cost, can be solved, but the heat resistance is lowered by being dominated by the binder as a matrix, and the content ratio of fluorine phlogopite crystal is low. Product quality deteriorates.

[Problems to be solved by the invention]

As a method for producing a new fluorophlogopite microcrystal-containing glass ceramics that solves the above-mentioned drawbacks of the conventional method, the present inventors have dissolved a component constituting fluorophlogopite in a polar solvent in an alkoxide compound and a polar solvent. A non-alkoxide compound mixed and dissolved is used as a starting material, which is hydrolyzed, dehydrated and dried, and then heat-treated to obtain a fluorine phlogopite ceramics sintered body. (Japanese Patent Application No. 59-70917) further advanced the research and completed a simpler, more economical and inexpensive manufacturing method.

[Means for solving problems]

The present invention relates to a solution (hereinafter referred to as an “alkoxide mixed solution”) obtained by dissolving a component of fluorine phlogopite in the form of an alkoxide compound and a fluorine compound in a polar solvent, and a finely ground fluorine solution. Fluorine phlogopite mica ceramics sintered with high heat resistance and excellent machinability by mixing with phlogopite mica powder, adding water to it to cause hydrolysis reaction, dehydrating and drying, and then heat treating It is a body manufacturing method.

In the present invention, the alkoxide mixed solution forms a glass matrix in the heat treatment sintering process, and plays a role of a binder for condensing the fluorophlogopite powder. Further, a part of the components of the glass matrix promotes the growth of fluorine phlogopite mica microcrystals derived from the fluorophlogopite mica powder, and crystallizes itself, and at the end of sintering, the fluorophlogene in the sintered body is completed. An isotropic sintered body having a structure in which mica crystals are closely intertwined is formed.

The crystals of fluorine phlogopite are likely to be oriented and anisotropy occurs during pressure molding, and in order to suppress this as much as possible, the fluorophlogopite crystals in the sintered body should be made as fine as possible. is necessary. That is, in order to obtain a fluorophlogopite mica ceramics sintered body having good machinability, the fluorophlogopite mica crystal has a size of 5 to 10 μm and has a structure in which they are closely entangled with each other without a space. It is necessary. For that purpose, the fluorophlogopite mica crystal contained in the raw material of fluorophlogopite mica powder is as small as possible, and the crystal grows in the sintering process to cause entanglement, and the size of 5 to 10 μm after the completion of sintering. It is necessary to be In order to satisfy this condition, it is desirable to use the raw material fluorophlogopite powder as fine powder having an average particle size of 1.5 μm or less.

The amount of the fluorine phlogopite powder used as a raw material is preferably 30 to 70% by weight of the content at the time of forming a product sintered body. When the ratio of the raw material fluorine phlogopite powder falls outside this range, the effect of the present invention that the heat treatment time is shortened cannot be obtained, while when the ratio increases beyond this range, the condensing effect of the glass matrix is increased. Insufficient to obtain a good quality sintered body, which is the object of the present invention.

The alkoxide mixed solution used in the present invention forms a glass matrix in the sintering process and serves as a sintering aid for coagulating the fluorophlogopite powder. The alkoxide mixed solution contains Si in a weight ratio at the time when the constituents of fluorine phlogopite in the form of alkoxide compound and fluorine compound are converted into oxides.
_{O 2 35~50%, Al 2 O} 3 10~30%, MgO10~30
%, K ₂ O _{3 to} 15% and F component 5 to 10% are preferable. When the amount of each component is within this range, the chemical composition of the glass matrix formed during the sintering process is similar to that of fluorophlogopite, and hence the affinity between the fluorophlogopite powder and the glass matrix is similar. It has a very good sex and its binding force is strong. Further, heat treatment in the sintering process causes precipitation of fluorine phlogopite crystals in the glass matrix. Due to this crystal precipitation, not only the fluorophlogopite crystals derived from the fluorophlogopite powder grow, but also new crystals are generated in the matrix, which are closely and complexly entangled with each other to form intercrystalline crystals. As a result, a high-strength fluorophlogopite mica ceramics sintered compact having a dense and isotropic property can be produced.

If the amount of each component in the alkoxide mixed solution deviates from the above range, the ability of the glass matrix as a sintering aid of the fluorophlogopite powder becomes insufficient. For example, if the amount of SiO ₂ increases, the growth of fluorine phlogopite crystals will be insufficient, and the amorphous glass matrix portion remaining after completion of sintering will increase, resulting in a sintered body with poor machinability. On the other hand, if the amount of SiO ₂ is reduced, the meltability of the matrix portion during sintering deteriorates, the surface of the fluorophlogopite powder cannot be sufficiently wet, and the sinterability decreases.
In addition, if the composition ratio is different from the above, other than fluorine phlogopite
Mg ₂ SiO ₄ etc. will start to crystallize as by-products.

The alkyl group of the alkoxide compound is a lower alkyl group,
In particular, it is desirable to use a C ₁ -C ₄ alkoxide.

As the fluorine compound, any liquid compound can be used, but as an example, boron trifluoride methanol complex salt [(CH ₃ OH) · BF ₃ ] is suitable.

The polar solvent, an alcohol (C ₁ -C _3), ketones (acetone, MEK, acetophenone, etc.) and the like are preferable. The amount used is based on the futon element mica ceramics standard,
A range of 5-15 per kg is suitable.

The alkoxide mixed solution is a soluble component that can be changed to another oxide such as B ₂ O ₃ , Li ₂ O, Rb ₂ O and Cs ₂ O in an amount of 15% or less by weight when converted to an oxide. May be contained. In addition, the soluble component in the alkoxide mixed solution does not need to be the entire amount of the alkoxide compound, and some of them are in the form of other compounds soluble in a polar solvent, such as KF, KOH, and H ₃ BO ₃ . It may be one.

In the present invention, a mixture of an alkoxide mixed solution and finely pulverized fluorine phlogopite powder is used as a starting material, and water is added to the starting material to carry out the hydrolysis reaction. The hydrolysis conditions are as follows. That is, the amount of water added is 1 to 10 times the theoretical amount required for the decomposition of alkoxide. If the amount is too small, the amount of fluorine phlogopite produced will be small. On the contrary, if the amount is too large, the hydrolysis rate of each alkoxide component will be significantly different, resulting in a nonuniform gel. The pH is preferably 6.5 or higher. If the pH is lower than this range, the hydrolysis of the silicon alkoxide will be slow and the gelation rate will be slow, so that a non-uniform gel is likely to be formed. Therefore, different compounds (for example, Mg ₂ SiO ₄ ) may be generated in the glass ceramics, which is not preferable. Further, the temperature is in the range of 25 to 100 ° C., 60 ° C.
Before and after is preferable. 40 ~ 100 ℃ after hydrolysis
If the heating is continued at, the alkoxide mixed solution part will gradually gel.

When this gel-like substance is further heated at 500 to 950 ° C. for 1 to 24 hours (hereinafter referred to as the first stage heat treatment), it becomes an amorphous glass matrix, and fluorine phlogopite crystals are present in this glass matrix. A substance in a state of being dispersed and suspended in is obtained. At the stage of this first-stage heat treatment, formation of celite and the like, which will be the nucleus of the formation of fluorine phlogopite crystals in the future, will begin to occur actively in the glass matrix phase, but the growth of fluorine phlogopite crystals is not remarkable.

During the process of the first-stage heat treatment, the volume of the solvent or excess water is volatilized so that the volume shrinks greatly, and the obtained substance is likely to have a distorted shape. Therefore, at this stage, it is crushed once into a fine powder and molded again into a desired shape.
It is preferable to perform the second stage heat treatment (sintering) at 00 to 1200 ° C.

The fluorophlogopite crystals that had been dispersed in the molded product by the second-stage heat treatment continued to grow with the help of the crystalline phase generated in the glass matrix phase, and the entangled crystals Forming phases. Accordingly, the size of the fluorophlogopite mica crystal of the final sintered body is 5 to 10 μm, and a good fluorophlogopite mica ceramics sintered body having a structure in which they are closely intertwined with each other is obtained.

In the first-stage heat treatment, it is necessary that fluorine phlogopite crystals are dispersed and suspended in the amorphous glass matrix phase, so that the matrix matrix phase is completely wet.

One of the purposes of the second-stage heat treatment is to grow fluorophlogopite crystals in the glass matrix phase at the same time as sintering, and the temperature is below the softening point (approximately 1400 ° C) of the fluorophlogopite crystals. To implement. The preferable temperature is in the range of 900 to 1200 ° C., and the firing time is 1 to 10 hours.

The fluorophlogopite mica ceramics sintered body obtained by the method of the present invention contains 40 to 80% by weight of fluorophlogopite mica crystals, and the flaky crystals of fluorophlogopite mica having a size of 5 to 10 μm are entirely contained. It is evenly and densely entangled and distributed.

The fluorine phlogopite mica ceramics sintered body obtained in the present invention,
Unlike the conventional method in which all fluorous phlogopite crystals are crystallized from amorphous glass matrix (for example, Japanese Patent Publication No. 54-34775), the raw material already contains a considerable proportion of fluorophlogopite crystals. Therefore, a sintered body having a high fluorine phlogopite crystal content can be easily obtained. On the other hand, in the conventional method of sintering the fluorophlogopite mica crystal powder with a sintering aid having a chemical composition different from that of the fluorophlogopite mica, the content rate of the fluorophlogopite mica crystal can be arbitrarily selected, but the entanglement of the crystals In addition, the crystal arrangement is likely to have anisotropy, and only the sintering aid binds the crystals, and the bond between the crystals is weak.
The machinability of the obtained sintered body is low. In addition, since the sintering aid has a lower melting point than the fluorophlogopite crystal, it is inevitable that the sintered body has low heat resistance.

The sintered body obtained in the present invention has extremely excellent machinability. That is, it is easy to drill with a drill or cut with a lathe. Further, since it has been heated at a temperature of about 1000 ° C. for a long time, this sintered body has sufficient strength as a mechanical member without causing shrinkage, deformation or strength deterioration.

〔Example〕

Hereinafter, the present invention will be further described with reference to examples. In the following examples, the machinability was evaluated by a lathe under the same cutting conditions (cutting speed 50 m / min, bite cutting amount 0.5 mm, bite feeding amount 0.05 mm / re).
v) was performed, and it was judged based on the amount of wear of the cutting tool, the magnitude of resistance during cutting, and the degree of surface finish. That is, the cutting length until the flank wear amount of the cutting tool reaches a certain size,
The magnitude of the force (main component force, feed component force and back component force) applied to the cutting tool during cutting and the state of the finished surface were measured and compared with a sample commercially available as free-cutting ceramics,
The quality of the performance was judged.

Examples 1 to 5 Ethyl silicate 40 (Colcoat KK trade name) 113
Part, magnesium methoxide (Mg (OCH ₃ ) ₂ ) 28 parts, potassium methoxide (KOCH ₃ ) 15 parts, boron methoxide (B (OCH ₃ ) ₃ ) 3 parts, boron trifluoride methanol complex salt (BF
₃ (CH ₃ OH)) and 172 parts of benzene, and aluminum isopropoxide (Al (i-OC ₃ H ₇ ) ₃ ) 7 previously dissolved.
A predetermined amount (42-233 parts) of fluorine phlogopite powder pulverized to 1 μm or less by mixing 2 parts in 1500 parts of methanol
The mixture was added and heated to reflux at about 70 ° C. to mix. After mixing for 1 hour, 200 parts of water adjusted to pH 10 was gradually added to carry out hydrolysis. After hydrolysis and gelation are complete 1
It was dried at 20 ° C. to obtain 180 to 370 parts of dried product. The dried material was crushed and subjected to the first stage heat treatment at 700 ° C. for 7 hours to obtain an amorphous substance 150 to 3 mixed with fluorine phlogopite.
30 parts were obtained. 500kgf / cm after crushing and granulating
^It was pressure-molded at 2, and the second stage heat treatment (1100 ° C., 5 hours) was performed to obtain 120 to 300 parts of a sintered body.

The fluorine phlogopite mica ceramics sintered body obtained in this manner is a uniform dispersion of the fluorophlogopite mica in the glass matrix,
It constituted a good sintered body, had good machinability, and a bending strength of 760 to 1080 kgf / cm ² . Table 1 shows manufacturing conditions and results. In addition, the numerical value in the column of the compounding ratio (%) in the table is the balance of alkoxides corresponding to 30 to 70 parts by weight of fluorophlogopite powder, and 100 parts by weight of the sintered product of the final product. It shows that the amount was blended (in the following Examples and Comparative Examples as well, it is indicated according to this).

Examples 6 to 19 The mixing ratio of the alkoxides was changed so that the composition of each component was as shown in Table 1, and the fluorophlogopite powder was 100 parts with respect to 100 parts of each oxide from the alkoxides in total. The mixture was mixed at a ratio and subjected to hydrolysis, heat treatment and the like in the same manner as in Examples 1 to 5 to obtain a fluorophlogopite mica ceramics sintered body. All show good machinability with a bending strength of 71.
It was 0 to 1050 kgf / cm ² . Table 1 shows manufacturing conditions and results.

Examples 20 to 43 The operating conditions such as the mixing ratio of alkoxides and fluorine phlogopite powder and hydrolysis were the same as in Example 3, and the heat treatment conditions of the first step and the second step were changed as shown in Table 1. To obtain a sintered body of fluorine phlogopite mica ceramics. The properties of the obtained sintered bodies are shown in Table 1, and all showed good machinability and bending strength.

Comparative Examples 1 to 9 Table 2 shows examples in which the blending ratio of alkoxides or the blending ratio of fluorophlogopite powder deviates from the preferable range as a comparative example. Compared with the case of the examples, the machinability and / or the flexural strength are all lower.

Front Page Continuation (72) Inventor Toshio Hamasaki 3826 Yumieda, Tagawa-shi, Fukuoka Prefecture Mitsui Kozan Co., Ltd.Tagawa Works (72) Inventor Katsuya Eguchi 3826, Yumizuta, Tagawa City, Fukuoka Mitsui Minesama Co., Ltd. Tagawa Works (56) References JP-A-60-215548 (JP, A)

Claims (1)

[Claims] 1. A solution obtained by dissolving a component of fluorophlogopite in the form of an alkoxide compound and a fluorine compound in a polar solvent, the component constituting fluorophlogopite in the form of an alkoxide compound and a fluorine compound. the, SiO ₂ 35 to 50% by weight at the time of an _{oxide, Al 2 O 3 10~30%,} MgO10
Time of 30%, a solution containing the K ₂ O3~15% and F components 5-10%, and a fluorine phlogopite powder pulverized, the amount of fluorine phlogopite powder was a sintered body With the content in
A method for producing a fluorophlogopite ceramics sintered body, which comprises mixing 30 to 70% by weight, adding water to the mixture to cause a hydrolysis reaction, dehydration and drying, and then heat treatment.