JPH0432783B2 - - Google Patents

Description

[Detailed description of the invention]

[Object of the Invention] Industrial Application Field The present invention relates to a method for producing machinable vitreous ceramics suitable for producing equipment parts and the like. 2. Description of the Related Art Ceramic materials such as glass-ceramic ceramics, which can be machined, are often used for parts of electrical equipment. Such vitreous ceramics include, for example,
Glass-ceramic articles are known which contain crystals of a fluorophlogopite solid solution dispersed at least 50% by volume, as disclosed in US Pat. This glass-ceramics is made by melting and vitrifying a raw material mixture and then precipitating fluorine phlogopite crystals.
It contains fine crystals in a disordered manner, has high airtightness, and is easy to machine such as cutting, but it has the problem of low yields due to the occurrence of many cracks, especially during the process of manufacturing glass bodies. Furthermore, in JP-A-61-72654, a vitrified molded product obtained by melting a fluorine-containing mixture whose main raw material is pottery stone and an easily vaporized fluorine compound are heated at 1100 to 1360 in a closed container. A method of crystallizing fluorine mica in a glass molded article by heating at .degree. C. is disclosed. According to this method, crystallized glass ceramics can be obtained in a short time, but the occurrence of cracks in the glass body manufacturing process and the strength of the product are not significantly improved. Problems to be Solved The fluorine-phlogopite-containing vitreous ceramics in the prior art as described above can be cut and have appropriate mechanical strength. There is not much of a problem when manufacturing small products, but if you try to manufacture large products (for example, 15 cm x 15 cm x 3 cm or more or equivalent size or more), vitrified molded products (hereinafter referred to as glass objects) ) had problems in that cracks were likely to occur and the yield was low. Furthermore, although a material with high strength is desired, there is a problem in that machinability deteriorates when raw material blending ratios and manufacturing conditions are selected that result in high strength. Therefore, the present invention overcomes the above-mentioned problems in the prior art and provides a method for producing large-sized vitreous ceramics with good machinability and sufficient mechanical strength at a high yield. This is what I am trying to do. [Structure of the Invention] Means for Solving the Problems The object of the present invention as described above is to provide a compound capable of producing chinastone, magnesium fluoride, magnesium oxide, a compound capable of producing potassium oxide, and boron oxide. Compounds that can be generated include alkali metals,
Elements contained in 100 parts of the total weight excluding ignition loss by blending a composite oxide of at least one metal oxide selected from alkaline earth metals and lead with zirconium dioxide. The content of silicon: 16 to 25 parts, aluminum: 6 to 9 parts, respectively.
parts, potassium: 5.5 to 12 parts, magnesium: 4.7 to
15 parts, zirconium: 0.7 to 5.0 parts, boron: 0.7 to
3.2 parts, fluorine: 3.0 to 9.3 parts, metal elements other than these elements: 7.0 parts or less, and the balance amount of oxygen,
a step of heating and melting said compound within a range of from at least 50° C. above the transition temperature of the glass body forming the melt obtained in said melting step to at least at least above said temperature. A step of obtaining a glass body by gradually cooling the glass body at a cooling rate of 100°C/hr or less to a temperature lower than 70°C, and a step of heat-treating the glass body at a temperature exceeding 1100°C and up to 1360°C in a container with a lid. This is achieved by a method for manufacturing vitreous ceramics comprising: That is, the vitreous ceramics obtained by the present invention contains suitable compounds capable of producing china stone, magnesium fluoride, magnesium oxide, potassium oxide, and boron oxide, respectively, as raw material components, and alkali metals and alkaline earth metals. ,
It is manufactured by blending a composite oxide of at least one metal selected from lead and zirconium dioxide. Pottery stone is a mineral whose main component is a complex oxide consisting of silica, alumina, and potassium oxide.
It is desirable to use one that is as pure as possible and does not contain any impurities. By using pottery stone that has a composite structure containing each of these components, it is possible to melt quickly and easily generate fine crystals, but the amount used is limited, excluding the loss on ignition of the compound. The aluminum content is in the range of 6 to 9 parts with respect to 100 parts of the total substantial weight (hereinafter simply referred to as the blend), and the silicon content is in the range of 6 to 9 parts, and the silicon content is greater than the silicon content contained in other raw materials. A range of 16 to 25 parts is suitable. By setting it within this range, appropriate crystallization that facilitates cutting can be achieved. Magnesium fluoride is blended so that the amount of fluorine is 3.0 to 9.3 parts per 100 parts of the compound, and compounds that can produce magnesium oxide are either magnesium oxide itself or magnesium hydroxide decomposed by heating. Contains a magnesium compound that produces magnesium oxide, and together with magnesium fluoride, magnesium is also 4.7 ~
It is preferable to use 15 parts. By setting it as this range, an appropriate degree of crystallinity can be obtained. As the potassium compound that can generate potassium oxide, compounds that can be decomposed to generate potassium oxide by heating, such as potassium carbonate and potassium borate, can be used, but as long as they do not significantly affect the composition of the formulation. Other potassium compounds may also be used. The amount of potassium compound used is preferably such that the potassium content in total with potassium oxide contained in other raw materials is 5.5 to 12 parts per 100 parts of the formulation. This is the range necessary to facilitate melting and provide adequate crystallinity. Compounds that can generate boron oxide include:
Compounds that decompose to produce boron oxide when heated, such as boric acid and potassium borate, can be used, but other boron compounds may not be used as long as they do not essentially affect the composition of the raw material mixture. Good too. The amount of these boron compounds used is preferably 0.7 to 3.2 parts of boron per 100 parts of the formulation. This is a range that facilitates melting and provides favorable glass forming properties. A composite oxide of zirconium dioxide and an oxide of at least one metal selected from alkali metals, alkaline earth metals, and lead is a composite oxide of zirconium dioxide and oxides, hydroxides, or carbonates of these metals. Zirconate salts obtained by melting zirconate, such as lithium zirconate, potassium zirconate, calcium zirconate, barium zirconate, and lead zirconate, are used. When using simple zirconia without these composite oxide structures or a mixture of zirconia and other metal oxides, most or only a small amount of zirconia remains undissolved, so that the desired effect of the present invention cannot be achieved. is not demonstrated. In the present invention, by blending a zirconium compound in the form of a composite oxide, it is possible to quickly melt and obtain a uniform glass, which not only greatly reduces the cracking rate in the manufacturing process of large glass bodies, but also During heat treatment, two types of uniform, fine crystals, fluorine phlogopite and zirconia, can be easily generated, and it is effective in increasing mechanical strength and machinability at the same time. The amount of the zirconium compound in the form of a complex oxide to be used is preferably 0.7 to 5.0 parts per 100 parts of the composition. Zirconium content
If it is less than 0.7 parts, a sufficient effect cannot be obtained, and if it exceeds 5.0 parts, it remains undissolved in the melt, which has an adverse effect on quality, which is not preferable. Furthermore, regarding alkali metals, alkaline earth metals, and other metals contained in the composite oxide, which are not specifically specified, the total amount thereof may be up to 7 parts as long as the properties of the resulting vitreous ceramics are not impaired. However, in general, if it exceeds 7 parts, problems such as impaired machinability occur, so it is not preferable. After the raw material mixture containing each of these components is sufficiently ground and mixed, it is melted in a high temperature furnace to obtain a glass melt having a glass transition temperature within the range of approximately 600 to 680°C. This melt is injected into the mold from a temperature of, for example, 730°C, i.e. at least 50°C above the aforementioned transition temperature range,
i.e. at least 70
When the temperature is lower than 100°C, the material is gradually cooled and solidified at a cooling rate of 100°C or less per hour to form a glass body. If the cooling rate at this time is too high, the internal strain of the obtained glass body will increase, and if an attempt is made to obtain a large glass body, cracks will occur and the yield will decrease. Furthermore, if the cooling rate is low, there will be no problem with the quality of the glass body or the yield, but it is not preferable because productivity will decrease. The glass body thus obtained was heated to 1100 mL in a container.
Heat treated at ~1360℃. At this time, if the container is open, the vapor of the fluorine compound will volatilize, so it is necessary to put a lid on the container. By doing this, the volatilization of the fluorine compound from the surface of the glass body can be minimized. It can be done. Note that by placing a small amount of a volatile fluorine compound, such as magnesium fluoride, in the container, volatilization of the fluorine compound from the glass body is suppressed. By heat-treating in the container in this manner, fine crystals of fluorine phlogopite and zirconia are uniformly dispersed and produced in the glass matrix, resulting in a glassy ceramic with excellent properties. Effects According to the method of the present invention as described above, it is possible to prevent the occurrence of cracking, which was a problem in the prior art, especially in the process of manufacturing large glass bodies, and not only to increase the yield, but also to improve the quality of the product. Improvements in both mechanical strength and machinability are achieved. Example 1 Refined chinastone having the chemical composition as shown in Table 1, magnesium fluoride, magnesium oxide, potassium carbonate, boric acid, and zirconium-containing composite oxides such as lithium zirconate, potassium zirconate, calcium zirconate, and zirconate, respectively. By using barium and lead zirconate, and by using zirconia instead of the zirconium-containing composite oxide, raw material mixtures having the composition ratios shown in Table 2 were obtained. Table 1 Components Weight % Loss on ignition 3.41 SiO ₂ 66.86 Al ₂ O ₃ 23.21 K ₂ O 5.55 Impurities 0.97 The raw material mixture was thoroughly mixed in a ball mill for 1 hour, charged into a crucible furnace, and melted at 1450°C. This was poured into a 25 cm x 25 cm x 4 cm square graphite mold, cooled from 750°C to 500°C over 5 hours, and then allowed to cool to approximately room temperature to obtain a glass body. Table 2 also shows the results of examining the glass transition point and cracking rate of such glass bodies. Next, the steam glass molded body was placed in an alumina container alongside a crucible containing magnesium fluoride, and an alumina lid was placed on it and placed in an electric furnace, where it was heated to 1150°C for 4 hours. The mixture was heated to a temperature of 100.degree. C., maintained at that temperature for 3 hours, and then slowly cooled. The bending strength and compressive strength of the obtained vitreous ceramics were measured, and the machinability was tested using a high-speed lathe. These results are also shown in Table 2.

【table】

[Table] (1) Control example (2) Control example (according to the method of Japanese Patent Publication No. 54-34775).
_{K2O instead} of _{K2CO3 and H3BO3} , respectively
and the content _{of B2O3} . (3) Measured by specific heat method. Error ±10℃. (4) If a glass body with an area of 25cm x 25cm is molded and a glass body with an area of at least 2cm x 20cm cannot be obtained due to the occurrence of cracks, it is considered cracked, and the number of cracked pieces is indicated based on the number of pieces produced. (5) The product shaped into a cylinder is cut into a carbide tool (K type).
The tool was cut using a lathe and the wear of the tool was observed using a microscope, and the degree of wear was evaluated on a five-point scale. Good: 1 → Bad: 5 Example 2 Molten glass was produced according to the formulations of test numbers 12 and 13 in Example 1, and then the same procedure as in Example 1 was made, except that the vitrification conditions and crystallization conditions were variously changed. Glassy ceramics were produced in the same manner. Table 3 shows the test results for the bending strength, compressive strength, and machinability of the obtained product.

〔Effect of the invention〕

The method for producing vitreous ceramics of the present invention includes:
By blending specific amounts of specific raw materials, forming a glass body under specific conditions, and then crystallizing it under specific conditions, it is possible to significantly reduce the cracking rate, especially when manufacturing large glass bodies, and improve physical strength. It has the advantage of being able to obtain large molded products with good machinability, high uniformity, and no defects at a high yield.

Claims (1)

[Claims] 1 At least one selected from alkali metals, alkaline earth metals, and lead is added to chinastone, magnesium fluoride, compounds capable of producing magnesium oxide, compounds capable of producing potassium oxide, and compounds capable of producing boron oxide. When a composite oxide of one metal oxide and zirconium dioxide is blended, the content of the elements contained in 100 parts of the total weight excluding ignition loss is 16 to 25 parts silicon, respectively. Aluminum: 6 to 9 parts, Potassium: 5.5 to 12 parts, Magnesium: 4.7 to 15 parts, Zirconium: 0.7 to 5.0
parts, boron: 0.7 to 3.2 parts, fluorine: 3.0 to 9.3 parts,
A step of obtaining a compound containing 7.0 parts or less of metallic elements other than these elements and a balanced amount of oxygen, a step of heating and melting the compound, and a step of melting the molten liquid obtained in the melting step. 100°C/100°C between a temperature at least 50°C higher than the transition temperature of the glass body to be formed and a temperature at least 70°C lower than said temperature.
a step of obtaining a glass body by slow cooling at a cooling rate of less than hr;
A method for producing vitreous ceramics, comprising a step of heat treatment at temperatures up to ℃.