JPH05155657A - Ceramics made of zeolite wherein high density leusite and/or porsite are incorporated as main ingredients - Google Patents

Abstract

PURPOSE: To control a thermal expansion coefficient by calcining K substitution zeolite powder at a prescribed temperature, turning it to amorphous powder, then compacting it and sintering it at a specified temperature further.

CONSTITUTION: The K salt solution of KCl or the like for generating K ions several times as much as an amount required for ion exchange is adjusted to a prescribed pH. The zeolite powder for which the ratio of SiO₂/Al₂O₃ is 3.5-7.5 of zeolite Y or the like is added and mixed in the K salt solution and heated and circulated for prescribed time, then, a mixture is filtered and washed and the zeolite powder for which a K composition is more than 50% of an ion exchange amount is obtained. Then, the K substitution zeolite is calcined at 900-1100°C for 0.5-2 hours in an atmosphere, pulverized and turned to the amorphous zeolite powder of a prescribed particle size. The powder is mixed with a binder, pressure-compacted and sintered at 1150-1400°C for 0.5-12 hours and a ceramic material for which a main crystal phase is leucite and porosity is less than 5% is obtained. By using Cs and Rb instead of K, leucite/pollucite and pollucite crystal phase are obtained.

COPYRIGHT: (C)1993,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a new method for producing a material which is substantially free of cracks and which has a porosity of 5% or less and which is a ceramic material mainly containing leucite or porusite. Is.

[0002]

2. Description of the Related Art Ceramic materials have many uses such as catalyst fixing materials, dental porcelain products, heat exchangers, turbine blades, and integrated circuit substrates. The particular ceramic used in a given application depends on the properties required for that application. For example, leucite ceramics can be used as a dental porcelain product or as a coating for metal-to-metal or metal / ceramic sealing.
(Leucite is also called leucite.) For an overview of the importance of the composition of potassium aluminosilicate in dental ceramics, see C. Hahn and K. Teuchert, Ber.
Dt. Keram. Ges., 57, (1980) Nos. 9-10, 208-215. The weakness of using leucite in dental applications is that it is easily broken and difficult to repair. For this reason, a metal frame is usually required when inserting dentures. Therefore, it is desired that leucite ceramics become stronger. Further, it is necessary to establish a method for producing leucite ceramics at a lower temperature so as to eliminate the steps of melting glass at a high temperature, making the frit, and crushing the glass. U.S. Pat. No. 4,798,536 showed that the addition of potassium salts to various feldspars produced porcelain with high leucite phase content and increased strength. Partially crystallized leucite glass-ceramics were produced by the method devised in this report, and their strength is stronger than that reported in the '536 document. That is, when zeolite Y powder substituted with potassium is used and heated at 1050 ° C., it becomes an amorphous powder. When this amorphous powder is molded into a predetermined shape and sintered at 1150-1400 ° C., it becomes a leucite ceramic material. This eliminates the need for melting the glass and making the frit.

Although there was a method for producing ceramics from zeolite in the prior art, there is no report on a procedure for producing a dense leucite ceramic material. For example,
D. W. Breck is a book on "Zeolite Molecular Sieves"
(John Wiley & Sons, New York (1974), p493-496)
, "When heating Mg-X, cordierite is formed." The publicly announced process Mg-X is heated at 1500 ℃ to make glass, and it is heated at 1000 ℃ or more to produce cordierite, which requires two steps to make cordierite. .. Another document that describes a method of making cordierite-based ceramic materials is Chowdry et al., US Pat. No. 4,814,303. Chowdry is a method for making single crystal anorthite, anorthite-cordierite, or cordierite-based ceramic material, which is zeolite X,-
Calcium, Ca / Mg, and Mg forms of Y and -A from about 900 ℃ to 135
It has been announced that heating is performed in the temperature range of 0 ° C. Chowdry
No. 33 of KAlSi ₂ was produced by preparing zeolite X substituted with potassium and sintering it at 1000 ℃.
It was alleged that a material that was O ₆ was formed, which must have shown the Leucite X-ray diffraction pattern (JCPDS file # 15-47). Finally, European Patent Publication No. 298,701 (Taga
Et al.) Describe the preparation of a ceramic material with anorthite phase from calcium zeolite. The process involves a calcination operation to form an amorphous material, which is shaped into a product and sintered at a temperature of about 850-950 ° C.

[0004]

The process of the present invention differs significantly from the prior art. First, the process of the present invention has two steps, while the process of Chouwdry has two steps. As illustrated, the two-step process is crucial for making useful ceramic materials. Next, the types of zeolite used in the process of this invention and the sintering conditions are
It is completely different from the one in the literature. The process of the present invention can also be used for producing a ceramic material whose main crystal phase is porcite. Porcite has a coefficient of thermal expansion
In the temperature range of 50-700 ℃, it is less than 2 × 10 ▲ superscript-6 ▼, and its melting point is more than 1900 ℃. Can be used in the field. This type of ceramic material can be produced by sintering at about 1250 ° C. using cesium-substituted zeolite instead of potassium-substituted zeolite.

Another problem with the application of leucite is its high coefficient of thermal expansion. Leucite undergoes a phase transformation (from tetragonal to cubic) between 400 and 600 ° C, resulting in a 5% expansion of the unit cell volume. Even at temperatures below this structural transition point, leucite and its glass-ceramics exhibit a relatively high coefficient of thermal expansion.
It has been stated in the previous technical documents that the thermal expansion of leucite glass / ceramics can be changed only within a narrow range by changing the ratio of leucite crystals in the sintered ceramic to the remaining glass. This method of varying the thermal expansion is described in U.S. Pat. No. 4,604,366, by mixing two different glass frits and two different ceramic powders in various ratios to produce a 10 × 10 ▲ superscript -6. It is said that it can be adjusted within the range from ▼ to 19 × 10 ▲ Superscript -6 ▼. The coefficient of thermal expansion of leucite is 2 × 10 in the temperature range of 50 to 700 ℃ ▲ Superscript -6 ▼
To 27 × 10 ▲ superscript -6 ▼ was invented. The change in the coefficient of thermal expansion is realized by introducing the porusite phase into the leucite ceramics. Porcite is a relatively low thermal expansion cesium
-Silica-alumina ceramics, which has a cubic high-leucite structure at room temperature and forms a solid solution with leucite in the temperature range below the solidus. As the proportion of cesium in the leucite ceramics increases, the coefficient of thermal expansion decreases to the point where the leucite / porcite has a high leucite cubic structure at room temperature, and thereafter the coefficient of expansion further increases as the cesium composition increases. Will continue to decrease. The leucite / porcite ceramics material can be produced by replacing the zeolite with potassium and cesium like zeolite Y and performing the steps described above. By varying the amounts of potassium and cesium in the starting zeolite and performing the steps described above, a solid solution of any desired leucite / porcite ratio can be obtained. Using potassium- and cesium-substituted zeolites as a starting material produces a uniform distribution of these cations and consequently achieves a homogeneity of these cations in the ceramic material. By changing the amounts of cesium and potassium in the starting material zeolite, the coefficient of thermal expansion of the ceramic material can be adjusted to any value within the above range of values. As described above, the new process makes it easier to control the coefficient of thermal expansion than the conventional technique and expands the range of the coefficient of thermal expansion that can be realized.

[0006]

The present invention relates to the following steps and materials. That is, a step for producing a ceramic material whose main crystal phase is tetragonal leucite, a step for producing a ceramic material whose main crystal phase is porusite, and a main crystal phase is rubidium-leucite A process for producing a certain ceramic material,
It relates to a process for producing a ceramic material whose main crystal phase is a leucite / porcite solid solution, and a ceramic material containing a leucite / porcite solid solution. Therefore, one of the embodiments of the invention is a process of producing a ceramic material having a porosity of 5% or less and substantially no crack, the main crystal phase of which is tetragonal leucite. The process involves calcining the potassium-substituted zeolite powder at a temperature of 900 ° to 1000 ° C for a time sufficient to collapse the zeolite lattice into an amorphous powder, and produce the amorphous powder. And then sinter it at a temperature of 1150 to 1400 ° C for 0.5 to 12 hours, resulting in
The above-mentioned ceramic material is obtained. Here, zeolite is a substance having a SiO ₂ / Al ₂ O ₃ ratio of 3.5 to 7.5.

Another embodiment of the present invention is a process for producing a ceramic material having substantially no cracks and a porosity of 5% or less. The main crystal phase is leucite / porcite solid solution, and the process is 900 to 1100 ℃ for zeolite powder which is simultaneously substituted with potassium and cesium, or zeolite powder which is substituted only with potassium and zeolite which is substituted only with cesium. At a certain temperature, calcination is performed for a sufficient time so that the zeolite lattice collapses into an amorphous powder,
The amorphous powder is molded and sinters at a temperature of 1150 ° to 1400 ° C.
It is to sinter for 5 to 12 hours to obtain the above-mentioned ceramic material. Zeolites with a Si0 ₂ / Al ₂ O ₃ ratio of 3.5 to 7.5 have here a potassium composition of zero to 100% of their ion exchange capacity and a cesium composition of zero to 100% of their ion exchange capacity and their total ion exchange capacity. At least 50% of capacity
It has a total composition of potassium and cesium. However, another embodiment of the present invention is a step of producing a material having substantially no crack and a porosity of 5% or less, the main crystal phase of which is porusite. The process is
A cesium-substituted zeolite powder with a ratio of Si0 ₂ / Al ₂ O ₃ of 3.5 to 7.5 900 to 1100 ° C calcination for a time sufficient to collapse the zeolite lattice into an amorphous powder at a temperature of 1100 ° C. Then, the amorphous powder is molded and sintered at a temperature of 1150 ° to 1400 ° C. for 0.5 to 12 hours to obtain the above-mentioned ceramic material.

Still another embodiment of the present invention is a step of producing a ceramic material having no cracks and a porosity of 5% or less, the main crystal phase of which is a lucite / porcite solid solution. This is the case where the material is an empirical formula expressed as a metal oxide and is xK ₂ O: yCs ₂₀ : zSiO ₂ : Al ₂ O ₃ . Here, x varies from 0.01 to 0.99, y varies from 0.01 to 0.99, and z varies from 3.5 to 7.5. Exceptionally, y is greater than 0.19 when z is 7.5. This ceramic has a coefficient of thermal expansion in the range of 50 ° to 700 ° C from 2 × 10 ▲ superscript -6 ▼ to 27 × 10 ▲ superscript -6 ▼.

Zeolites are an essential component of the process of this invention. Zeolites have a well-known three-dimensional lattice structure with micropores. Generally crystalline zeolites are AlO ₂ and Si.
Formed from corners distributed by tetrahedrons of O ₂ , having uniform-sized micropores, large ion-exchange capacity, and adsorption dispersed inside micropores or crystal voids. It is characterized by the ability to reversibly desorb a phase (without displacing the atoms that form the basis of the crystal structure). Zeolites can be represented by the formula M ₂ / nAl ₂ O ₃ : xSiO ₂ as an anhydride. Where M is a cation with valence n and x is generally equal to or greater than 2. In naturally occurring zeolites, M is Li, Na, C
a, K, Mg and Ba. The M cations are loosely bound to the crystal structure and can be wholly or partially exchanged with other cations by conventional ion exchange techniques. Zeolites used in this invention, the 3.5 ratio of Si0 ₂ / Al ₂ O ₃
It contains all zeolites that can be synthesized between 7.5. Also, the necessary condition of the cation in the zeolite is that it can be replaced with potassium, cesium, rubidium, or a mixture of potassium and cesium. Examples of zeolites with this characteristic are zeolite Y, zeolite L, zeolite LZ-210, zeolite B, zeolite.
Omega, zeolite LZ-202, and zeolite W. Zeolite LZ-210 is obtained by increasing the silicon composition of zeolite Y by treatment with ammonia fluorosilicate ((NH ₄ ) ₂ SiF ₆ ) water. The preparation and characterization of this zeolite is described in the document accompanying US Pat. No. 4,503,023. Zeolite LZ-202 is an omega-type zeolite made without a template agent, the process of which is described in the document attached to U.S. Pat. No. 4,840,779. Of these zeolites, zeolite Y, L,
B, W and Omega are suitable.

Although Zeolite Y is used as an example of the process in the following description, it is by no means meant that the invention is limited to Zeolite Y. Zeolite Y is Na ₂ O: Al ₂ O
₃ : Synthetic zeolite represented by the formula xSiO ₂ , where x is a value in the range of 3 to 6. US patent for synthesizing zeolite
It is described in the document attached to No. 3,130,007. This synthetic method basically requires the preparation of a mixture of sodium aluminate, sodium silicate, colloidal silica, and sodium hydroxide, which is produced at 20 ° to 175 ° C.
At a certain temperature, the product is taken out by heating under autogenous pressure for a time sufficient to confirm complete crystallization, usually about 16 to 40 hours.

Generally two techniques are sodium cations,
Or remove other cations and remove it with potassium,
Used to exchange for cesium, rubidium, or a mixture of potassium and cesium. One is a method of exchanging potassium cations with various kinds of ions, and the other is that the zeolite is first exchanged with a cation such as NH ₄ ▲ superscript + ▼, and then potassium ions and ions are exchanged. It is a way to exchange. Ion exchange can be effectively carried out by exposing the zeolite to an aqueous solution of metal ions to be exchanged. For example, prepare a dilute aqueous solution of potassium chloride or potassium nitrate (about 1 mol) and adjust the pH of the solution.
Is adjusted to about 8.5 with potassium hydroxide. The volume of the solution to be prepared is an amount that can supply about 5 to 10 times the amount of sodium in the zeolite or the amount of potassium necessary for completely ion-exchanging unnecessary alkali metals. A batch process is effectively used to contact the potassium salt solution with the zeolite. Therefore, the solution is mixed with the zeolite powder and refluxed for about 2 hours. Next, the mixed solution is filtered to remove the zeolite powder. The batch is treated with fresh solution and the procedure is repeated until the potassium composition is at least 50%, preferably at least 90% of the ion exchange capacity of the zeolite. Mole
The definition of the ion exchange capacity of zeolite in units of / g is:
Mol / g of aluminum in the zeolite substructure when the monovalent cation is replaced by zeolite. As an alternative method of potassium exchange, the well-known continuous method such as putting zeolite in a cylinder and flowing a potassium solution through the cylinder or using a basket centrifuge can be used. The continuous method is advantageous in that the potassium solution can be used more effectively.

Next, potassium Y-substituted zeolite Y is 90
It is calcined at a temperature of 0 to 1100 ° C, preferably 1000 to 1075 ° C for 0.5 to 2 hours, that is, heated in the atmosphere. This calcination destroys the structure of the zeolite and turns it into an amorphous powder, but when it is shaped into a ceramic material (at the stage of the unsintered material), it is compared to the case of using non-calcined zeolite. Higher density. The effect of this calcination treatment is to minimize or eliminate cracks and distortions in the shape thereof contained in the finished ceramic material, and the finished material is substantially free of cracks and distortions. Agglomeration of the zeolite will occur during calcination. Therefore, the calcined (amorphous) powder was sieved to 60 mesh (US standard, 250
It is preferable to use only powder that has passed through (μ hole diameter). Of course, the calcined powder can be further crushed using a conventional crusher such as a ball mill, an attrition mill, an impact mill, or the like so that the powder particle size becomes 60 mesh or less. By using a powder having a small particle size, a ceramic material with less cracks can be produced and the work can be facilitated. A well-known technique may be used to form the amorphous powder into a desired shape. A typical molding method is to load the zeolite powder into a metal die and use 500 to 50,00.
Pressurization at a pressure of 0 psi (3,440 to about 344,000 kPa).

A binder may be added to the powder to aid its shaping. The binder will be selected from the well-known materials such as polyvinyl alcohol and polyethylene glycol. If a binder is added, its amount is up to 15 weight percent of the zeolite powder. When the molding of zeolite substituted with potassium is completed,
The molding material is from 1150 ° to about 1400 ° C, preferably 1200
Sintered at temperatures from ° to 1300 ° C for 2 to 6 hours.
It has been found that the ceramic material obtained after sintering has tetragonal leucite as the main crystal phase. "mainly"
The expression means that at least 90% of the crystalline phase is leucite. The obtained ceramic material has substantially no cracks and a porosity of 5% or less. "Substantially crack-free" means visually free of cracks. Porosity can be measured by conventional techniques such as scanning electron microscopy or transmission electron microscopy for microstructural analysis.

A ceramic material containing porusite as a main crystal phase can be produced by a method similar to that described for the leucite ceramic material. The zeolite is replaced with a cesium salt, ie cesium nitrate, in a procedure similar to that described above for potassium replacement. The amount of cesium to be replaced is at least 50%, preferably at least 90% of the ion exchange capacity of the zeolite. The cesium-substituted zeolite is treated in the same manner as the above-mentioned potassium-substituted zeolite to produce a ceramic material having porcite as a main crystal phase. In a similar manner, zeolites can be replaced by rubidium instead of potassium or cesium. Rubidium substitution is rubidium chloride,
Alternatively, it is carried out in the same manner as the potassium or cesium substitution except that rubidium nitrate is used. The rubidium-substituted zeolite is then treated in the same manner as described for potassium-substituted zeolites to make a ceramic material with the rubidium-leucite phase as the predominant crystal phase.

The present invention also relates to a process for producing a ceramic material whose main crystal phase is a solid solution of leucite / porcite. By changing the amount of porusite in the ceramic material, its coefficient of thermal expansion can be increased from 2 × 10 ▲ to −6 ▼ to 27 × 10 in the temperature range from 50 to 700 ° C.
▲ Superscript -6 ▼ Can be changed to ℃. When making a ceramic material made of a leucite / porcite solid solution, a zeolite such as zeolite Y is first substituted to obtain the potassium form as described above, and the cesium chloride, cesium hydroxide or cesium nitrate Is replaced with a cesium salt such as When both potassium and cesium are present in the zeolite, that is, they are simultaneously replaced, the potassium composition is between zero and 100% of the ion exchange capacity of the zeolite, and the cesium composition is also between zero and 100% of its ion exchange capacity. In between, the total potassium and cesium composition is at least 50% of the ion exchange capacity, preferably 90% or more. As the amount of cesium in the zeolite increases, the coefficient of thermal expansion decreases. Therefore, changing the concentrations of potassium and cesium provides a step of controlling the coefficient of thermal expansion of the ceramic material containing the leucite / porcite solid solution. Once the zeolite containing potassium and cesium is obtained, it is treated in the manner described above to obtain a ceramic material containing a leucite / porcite solid solution as the main phase. Instead of using a zeolite substituted with both potassium and cesium, two types of zeolite powder (which may be of the same or different structure type) may be used. That is, one with only potassium and the other with only cesium. Mix the two zeolite powders together to produce the desired potassium-cesium ratio, and eventually use the desired leucite. It will lead to the ratio of Polcite. The abundances of potassium and cesium are equal in the case of simultaneous substitution. Both methods can be used, but they do not always give the same results. Therefore, it is preferable to use a zeolite powder containing both potassium and cesium.

The leucite / porcite ceramic material can be described as a metal oxide by the following empirical formula. xK ₂ 0: yCs ₂ 0: zSi 0 ₂ : Al ₂ 0 ₃ where x varies from 0.01 to 0.99, y varies from 0.99 to 0.01, and z varies from 3.5 to 7.5. When z is 7.5,
y is greater than 0.19. This ceramic material is 50 ° to 70
The thermal expansion coefficient is 2 × 10 ▲ superscript -6 ▼ 7 × 1 between 0 ℃
0- ▲ Superscript -6 ▼ It has the feature that it changes to ℃. Porosity less than 5%, very high fire resistance, 1450
Has a melting point above ℃. Finally, the main crystalline phase of the ceramic material is leucite / porcite solid solution, which is leucite / porcite. The proposed leucite / porcite ceramic material has several applications, including dental porcelain and metal / ceramic seals where the coefficient of thermal expansion is graded in the transition region between metal and ceramic. ing.

Example 1 In this example, potassium-substituted zeolite Y is produced from NaY zeolite.
Dissolve 3.7 g of KCl in 3 liters of distilled water in a container,
The pH of the solution was adjusted to 8.5 by adding a small amount of KOH. To this solution, 150 g of NaY was added, and USP 3,130,00
By making it according to the procedure of No. 7, the chemical composition is 19,
_{52wt.% Al 2 0 3,} 41.45wt.% Si0 2, 12.82wt.% Na 2 O, and so is 26.21wt.% LOI. The chemical formula expressed as the ratio of oxides based on anhydride was 1.08Na ₂ O: 1.00Al ₂ 0 ₃ : 3.61Si 0 ₂ . The resulting slurry was refluxed for 2 hours with stirring.
Heated. The zeolite powder is filtered off and the replacement operation is repeated three more times, always with an equal volume of fresh KCl solution (pH adjusted to 8.5), before the final filtration operation. The powder is then washed with 9 liters of distilled water. The powder thus extracted is dried at room temperature. The component _{analysis, 20.2wt.% Al 2 0 3} ,
41.0wt.% Si0 ₂ , 0.188wt.% Na ₂ O, 17.0wt.% K ₂ O, and
It was shown to be 22.2 wt.% LOI. The chemical formula expressed as the ratio of the anhydrous oxide was 0.02Na ₂ O: 0.91K ₂ O: 1.0Al ₂ O ₃ : 3.4Si 0 ₂ .

[Example 2] LZ-Y62 (usually 2.7 wt.% Residual N
a ₂ O in Si0 ₂ / Al ₂ 0 ₃ ratio 53.3 lb. H ₂ 0 samples 360 lb. of the Y zeolite substituted with about 5 ammonium) and 40 l
b. Slurried with NH ₄ Cl. The mixture is refluxed for 1 hour and filtered on a filter press, the powder being left in the filter press for ion exchange. 40 l
A fresh solution of b. NH ₄ Cl and 360 lb. of H ₂ 0 is piped to a filter press, heated and refluxed in a kettle. Zeolite powder is added to this solution for 2 hours,
It is circulated through the filter press and is also passed through a heated kettle to bring the reflux temperature as close as possible. Three
A single exchange operation is carried out in the above circulation path, using an equal volume of fresh NH ₄ Cl solution each time. Finally zeolite powder left in the filter press machine is washed with H ₂ 0 of 75 gallons. The moist powder is removed from the filter press and dried overnight at 100 ° C. 17.8w in component analysis
_{t.% Al 2 0 3,} 51.7wt.% Si0 2, 8.7wt.% (NH 4) 2 O, 0.31wt.% N
It was found to have a ₂ O and 29.7 wt.% LOI. Formula expressed as the ratio of free hydroxide _{0.03Na 2 O: 1.0Al 2 0 3} : 4.9Si0 2: 0.96 (NH 4) was ₂ O.

Example 3 500 g of the ammonium-substituted zeolite Y produced in Example 2 is substituted as follows. In a vessel 1011.1 g KNO ₃ is dissolved in 10 liters H ₂ O and the pH is adjusted to about 9 with a small amount of KOH. The zeolite powder becomes a slurry in solution and the mixture is heated, stirred and refluxed for 2 hours. Then, the zeolite powder is separated by a filter, further subjected to an ion exchange operation three times, and an equivalent amount of fresh KNO ₃ solution (adjusted to pH 9) is used each time. Finally, the powder is washed with 15 liters of distilled water and dried at room temperature. Component analysis is 16.4 wt.% Al ₂ O ₃ , 48.0 wt.% Si 0 ₂ , 14.5 wt.% K ₂ O,
Then, it was 21.0 wt.% LOI, and when expressed by the ratio of anhydrous oxide, it was 0.96K ₂ O: 1.0Al ₂ 0 ₃ : 5.0Si 0 ₂ .

Example 4A This example is a method for producing ceramic pellets using the potassium-substituted zeolite Y used in Example 3. The two pellets are
Approximately 1 g of potassium-substituted zeolite Y 0.5 inch (1.27c
m) diameter steel die, 10,000psi (68950kP
It is formed by compressing in a). The two pellets are heated at 6 ℃ / min to 1050 ℃ and held at 1050 ℃ for 4 hours. The heated pellets are white, chalky and apparently not sintered at a density of 1.55.
It was 1.55 g / cc. One of the pellets was ground into a fine powder and subjected to X-ray diffraction, which pellet was shown to be amorphous.

Example 4B This example is a method for producing ceramic pellets using the potassium-substituted zeolite Y used in Example 3. 2 pellets
Approximately 1 g of potassium-substituted zeolite Y 0.5 inch (1.27c
m) diameter steel die, 10,000psi (68950kP
It is formed by compressing in a). The two pellets are heated at 6 ° C / min to 1150 ° C and held at 1150 ° C for 4 hours. The sintered pellets were vitreous, light gray and had densities of 12.31 and 2.32 g / cc. One of the pellets was ground into a fine powder and then subjected to X-ray diffraction, which revealed that the pellet was amorphous.

Example 4C The same pellets as in Example 4A above were prepared using the same potassium-substituted zeolite powder. The pellet was heated to 1150 ° C at 6 ° C / min and kept at 1150 ° C for 12 hours. The appearance of the two sintered pellets is similar to that of Example 4B and its density is 2.32.
It was 2.29 g / cc. One of the pellets was ground to a fine powder and then subjected to X-ray diffraction, which showed that the pellet contained tetragonal leucite (JCPDS file No. 15-47).

Example 4D Approximately 25 g of potassium-substituted zeolite Y was added as described in Example 3, 2.25 inches (57 m).
The pellets were made by placing in a m) diameter steel die and pressing at 3000 psi (20685 kPa). At that stage, the diameter of the pellet was 57.15 mm. The pellets were heated at 10 ° C / min to 1050 ° C, then at 4 ° C / min to 1250 ° C and held at 1250 ° C for 4 hours. The pellets after sintering were severely cracked. The diameter measured in the area without small cracks was 39.3 mm, showing a shrinkage of 31% in the diameter of the pellet.

Example 4E In the same manner as in Example 3, a small rectangular pellet of potassium-substituted zeolite Y having a length of 0.26 "(6.6 mm) was placed on a horizontal thermal dilatometer and The length direction was set to be the axis of shrinkage measurement.The pellets were heated at 6 ° C / min to 1400 ° C.The sintered pellets had a final length of 0.19 "(4.8mm), 27%. It showed linear shrinkage. The pellet was finely crushed into powder and subjected to an X-ray diffraction experiment. As a result, the presence of tetragonal leucite was observed as in Example 4B. Examples 4A to 4E showed that the method of producing a ceramic material by a one-step operation gave very unsatisfactory results. Leucite begins to form only after heating at 1150 ° C for 12 hours. It was then found that the moldings (pellets) shrink considerably (at least 27% shrinkage) due to sintering.

Example 5A As in Example 3, about 5 g of potassium-substituted zeolite Y was heated at 1050 ° C. for 1 hour without being powdered. Six pellets were formed by pressing the calcined powder in a 0.5 inch (12.7 mm) steel die at 10,000 psi (68950 kPa). The heating rate used in the following experiments was 4 ° C / min. The three pairs of pellets were heated for 4 hours at 1150 °, 1250 °, and 1350 ° C, respectively. The average densities of the pellets sintered at the three processing temperatures were 2.31, 2.345, and 2.39 g / cc, respectively. One from each pellet pair was taken out, powdered and subjected to X-ray diffraction. X-ray diffraction measurements of the three powders showed the following crystalline phases. Corresponding to each sintering temperature, tetragonal leucite, 12
It was tetragonal leucite at 50 ° C and tetragonal leucite at 1350 ° C. The leucite glass treated at 1250 ° C showed the highest crystallinity.

Example 5B In the same manner as in Example 3, about 100 g of potassium-substituted zeolite Y was heated as it was at 10 ° C./min to 1050 ° C. without being molded, and kept at 1050 ° C. for 1 hour. Approximately 45 g of the calcined powder was packed into a 57.15 mm diameter circular steel die and compression molded at 3000 psi (20685 kPa). Similarly, about 9 g of calcined powder has a diameter of 82.55 mm and a depth of 9.5 mm.
It was packed in a die and compression molded at 4000 psi (27580 kPa). The pellets were heated in an electric furnace at 10 ° C./min to 1050 ° C., at 4 ° C./min to 1250 ° C., and kept at 1250 ° C. for 4 hours. This heating scheme is the same as that used in Example 4D. The result of this heat treatment was minimal strain and no cracks were found. The round pellets had a diameter of 44.95 mm and a density of 2.37. On the other hand, when the cross section was rectangular and rod-shaped, the length was 66 mm and the density was 2.26 g / cc. Linear shrinkage during sintering is 20-21% for calcined powder
And it is much smaller than the case of non-calcined powder.
The latter typically showed 27-33% shrinkage. The degree of shrinkage of the non-calcined powder formed practically makes it impossible to produce ceramics without cracks and distortion. On the other hand, if calcined powder is used, a strong and defect-free product can be smoothly produced.

[Example 5C] A rod having a rectangular cross section prepared in Example 5B was 2.0 in (50.8 m) with a diamond cutter.
It was cut at the length of m). Small test pieces were ground in fine powder for X-ray diffraction. X-ray diffraction measurements revealed that tetragonal leucite was the only crystalline phase. 2.
The test piece of 0in was loaded in the thermal expansion meter, and about 4 ℃ / min
It was heated up to 800 ℃ and measured. 50 ° −700 calculated
Average thermal expansion coefficient in the range of ° C. is corrected based on the standard Al ₂ 0 _3, were ▼ 26.7 × 10 ▲ superscript -6 ▼ ° C. ▲ superscript -1. The transformation from tetragonal to cubic (low temperature to high temperature leucite) occurred at about 410 ℃ from the thermal expansion curve.

Example 6A For the potassium-substituted zeolite Y made in Example 1, small rectangular pellets were made by pressing the powder into a rectangular die at 5000 psi (34475 kPa). The length of the pellet was 0.272 in (6.9 mm). The pellet was loaded in a thermal dilatometer so that the length direction was parallel to the measurement axis, and heated to 1350 ° C at 6 ° C / min. The final length of the sintered pellets was 0.181 in (4.6 mm), and a linear shrinkage of 33% occurred. As a result of crushing the pellets into fine powder and performing X-ray diffraction, it was found that the only crystal component was tetragonal leucite.

Example 6B About 15 g of the potassium-substituted zeolite Y produced in Example 1 was heated to 1000 ° C. for 1 hour in a powder state. 88.55 m long as in Example 5A
A rod with a rectangular cross-section at m was made from calcined powder using a steel die. The bar was heated at 10 ° C / min to 1000 ° C, then 4 ° C / min to 1250 ° C and held at 1250 ° C for 4 hours. Use a diamond cutter on the heated rod 2.
It was cut to a length of 0 in (50.8 mm). The measured density of the bar is 2.36
It was g / cc. Crush a short test piece of the same rod into fine powder, and
As a result of line diffraction, it was found that there was tetragonal leucite. Load the rod into a self-recording thermal dilatometer, 4 ℃ / m
Heated to 900 ° C in. Average thermal expansion coefficient in the range of 50 ° -700 ° C. as determined by the calculation is corrected based on the standard Al ₂ 0 _3, 2
It was 8.0 × 10 ▲ superscript -6 ▼ ° C ▲ superscript -1 ▼. Transformation from tetragonal to cubic (low temperature leucite to high temperature leucite) Although not clear in this ceramic composition, there is a slight slope change in the thermal expansion curve between 500 ° and 650 ° C, suggesting its existence. It was

Example 7 This example illustrates the preparation of zeolite substituted with cesium and potassium. The potassium-substituted zeolite Y produced by the method shown in Example 3 is replaced with cesium as follows. 33 in container
1.35 g of cesium nitrate was dissolved in 1.7 liters of water and the pH was adjusted to 8 with a small amount of CsCO ₃ . 100 g of zeolite powder was put into the solution to form a slurry, and the mixture was heated and refluxed with stirring for 2 hours. The powder was isolated by filtration. 2 more ion exchange operations like this
Each time, it was repeated with an equal volume of CsN0 ₃ solution that was freshly prepared and pH was adjusted. The final powder is separated by filtration 15
It was washed with liters of deionized water and dried in air at room temperature. The result of the component analysis is 14.1 wt.% Al ₂ O ₃ , 41.4 wt.
% Si0 ₂ , 3.01 wt.% K ₂ O, 27.2 wt.% Cs ₂₀ and 15.8 wt.%
It was LOI. The ratio of anhydrous oxide is 0.70C
s ₂ 0: 0.23K ₂ O: 1.0Al ₂ 0 ₃ : 4.95Si 0 ₂ .

Example 8A About 5 g of the zeolite Y substituted with cesium and potassium prepared in Example 7 was heated to 1050 ° C. for 1 hour without molding. Six pellets were pressed from the calcined powder in a 0.5 in (12.7 mm) steel die at 10,000 psi (68950 kPa). The heating rate used in the following experiments is 4 ° C / min. The three pellet pairs were held for 4 hours at temperatures of 1150 °, 1250 ° and 1350 ° C, respectively. The average densities of the sintered pellets at the three heat treatment temperatures are 2.71, 2.76 and 2.77 g, respectively.
It was / cc. One test piece of each pair was crushed into fine powder and subjected to X-ray diffraction. As a result, the following crystal phase was shown.
It was 1150 ° C.-amorphous, 1250 ° C.-porcite (cubic leucite), and 1350 ° C.-porcite (cubic leucite) for each sintering temperature.

[Example 8B] About 5 g of the cesium / potassium-substituted zeolite Y prepared in Example 7 was calcined to 1050 ° C for 1 hour without molding. The powder was passed through a standard 60-mesh sieve (hole diameter: 0.21 mm) to remove a large lump, and the powder was molded into a rod having a length of 82.55 mm and a rectangular section with a side of 9.5 mm in a steel die. The stick is 10 ℃ / mi
n up to 1050 ° C, then 4 ° C / min to 1250 ° C, 1
It was kept at 250 ° C for 4 hours. The heat-treated rod was cut with a diamond cutter to a length of 2.0 in (50.8 mm). The measured density of the bar was 2.73 g / cc. Short test pieces of the same rod were crushed into fine powder and subjected to X-ray diffraction. As a result, it was found that cubic leucite was present. The rod was loaded into a thermographic dilatometer and heated to 875 ° C at 4 ° C / min. The average coefficient of thermal expansion in the range of 50 ° -700 ° C calculated is the standard A
is corrected based on l ₂ 0 _3, were ▼ 4.47 × 10 ▲ superscript -6 ▼ ° C. ▲ superscript -1. No sign of any structural transformation was found in the thermal expansion curve.

Example 9 50 g of potassium-substituted zeolite Y prepared as in Example 3 was substituted as follows (with cesium and potassium-substituted zeolite Y). 7.14 g of cesium chloride was dissolved in 212.5 ml of water in a container, and the pH was adjusted to 7.5 with a small amount of CsCO ₃ . Zeolite powder was poured into the solution to form a slurry, and the mixture was heated and refluxed with stirring for 2 hours. The powder was isolated by filtration, washed with deionized water until free of chloride and dried in air at room temperature. The results of component _{analysis, 15.18wt.% Al 2 0 3} , 10.9wt.% K 2 O, 8.9wt.% Cs 2 0, cation ratio in the substituted zeolite is 78% K and 22% Cs
Met.

Example 10 About 10 g of the potassium-cesium-substituted zeolite Y prepared in Example 9 was calcined at 10 ° C./min to 1050 ° C. for 1 hour without molding. The powder was molded in a steel die into a rod having a length of 82.55 mm and a rectangular cross section with a side of 9.5 mm. The bar was heated at 10 ° C / min to 1050 ° C, then 4 ° C / min to 1250 ° C and held at 1250 ° C for 4 hours. The heat-treated bar had no cracks. 2.0 in (50.
8 mm) was cut. The measured density of the bar was 2.49 g / cc. Short test pieces of the same rod were crushed into fine powder and subjected to X-ray diffraction. As a result, it was found that there were high temperature tetragonal leucite. Load the rod into a self-recording thermal dilatometer, 77 at 4 ℃ / min.
Heated to 5 ° C. Average thermal expansion coefficient in the range of 50 ° -700 ° C. as determined by the calculation is corrected based on the standard Al ₂ 0 _3, 14.1 × 1
It was 0 ▲ superscript -6 ▼ ° C ▲ superscript -1 ▼. No sign of any structural transformation was found in the thermal expansion curve.

[Example 11] Potassium zeolite L is identified by product number 3069, and the anhydrous oxide ratio by component analysis is
_{1.1K 2 O: 1.0Al 2 0 3} : 6.4Si0 was _2. About 5g of this sample
Was heated to 1050 ° C. for 1 hour without molding. 6 pellets of this calcined powder 0.5 in (12.7 m
m) in a steel die at 10,000 psi (68950 kPa). The heating rate used in the following experiments is 4 ° C / min. The three pellet pairs were held for 4 hours at temperatures of 1150 °, 1250 ° and 1350 ° C, respectively. The density of the three sintered pellets could not be measured due to the rather viscous flow during sintering. One test piece of each pair was crushed into fine powder and subjected to X-ray diffraction. As a result, the following crystal phase was shown.
1150 ℃ -Tetragonal Leucite, 125 for each sintering temperature
They were 0 ° C.-tetragonal leucite and 1350 ° C.-tetragonal leucite.

[0036]

INDUSTRIAL APPLICABILITY The ceramics containing porusite as a main component of the present invention has high fire resistance and can be usefully used in the fields of metal and ceramic seals. Further, the ceramic according to the method of the present invention has an industrial effect that it is easy to control the coefficient of thermal expansion.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Edit M. Flanigan United States, 10603 New York, White Plains, 502 Woodland Hills Road

Claims (10)

[Claims] 1. A process for producing ceramics which is virtually free of cracks, has a porosity of 5% or less, and whose main crystal phase is tetragonal lucite. It calcinates the powder of potassium-substituted zeolite at a temperature of 900 ° to 1100 ° C for a time sufficient to collapse the structure of the zeolite into an amorphous powder, and then bring the amorphous powder into the desired shape. Molded and 1150
In this step, the above ceramic material is obtained by sintering at a temperature of ° to 1400 ° C for 0.5 to 12 hours. What is zeolite here?
A substance with a SiO ₂ / Al ₂ O ₃ ratio of 3.5 to 7.5. 2. The starting material zeolite is zeolite Y,
The process of claim 1 when selected from Zeolite B, Zeolite L, Zeolite W, and Zeolite-Omega groups. 3. The process according to claim 1, wherein the amount of potassium in the potassium-substituted zeolite is at least 50% of the ion exchange capacity of the zeolite. 4. A process for producing ceramics which is virtually free of cracks, has a porosity of 5% or less, and has a major crystal phase of a lucite / porcite solid solution. It calcinates a zeolite powder containing potassium and cesium substituted cations at a temperature of 900 ° to 1100 ° C for a time sufficient to collapse the zeolite structure to an amorphous powder. Here, zeolite is a substance with a SiO ₂ / Al ₂ O ₃ ratio of 3.5 to 7.5, the potassium composition is between zero and 100% of the ion exchange capacity of the zeolite, and the cesium composition is also zero of its ion exchange capacity. To 100% and the sum of potassium and cesium composition is at least 50% of the ion exchange capacity.
Is. Next, the amorphous powder was molded into a predetermined shape, and 1150
In this step, the above ceramic material is obtained by sintering at a temperature of ° to 1400 ° C for 0.5 to 12 hours. 5. The process according to claim 4, wherein the zeolite powder is replaced simultaneously with potassium and cesium cations. 6. The process of claim 4 where the zeolite powder is a mixture of potassium substituted zeolite and cesium substituted zeolite. 7. The starting material zeolite is zeolite Y,
7. The process of claim 4, 5 or 6 when selected from Zeolite B, Zeolite L, Zeolite W, and Zeolite-Omega groups. 8. A process for producing ceramics, which is virtually free of cracks, has a porosity of 5% or less, and whose main crystal phase is rubidium-rucite. It involves calcining rubidium-substituted zeolite powder at a temperature of 900 ° to 1100 ° C for a time sufficient to collapse the structure of the zeolite into an amorphous powder, and This is a process of forming into a shape and sintering at a temperature of 1150 ° to 1400 ° C for 0.5 to 12 hours to obtain the above ceramic material. Here, zeolite is a substance having a SiO ₂ / Al ₂ O ₃ ratio of 3.5 to 7.5. 9. A process for producing ceramics, which is virtually free of cracks, has a porosity of 5% or less, and whose main crystal phase is porcite. It calcinates cesium-substituted zeolite powder at a temperature of 900 ° to 1100 ° C for a time sufficient to collapse the zeolite structure into an amorphous powder, and then bring the amorphous powder into the desired shape. Molded, 1150 ° to 14
This is a process of sintering at a temperature of 00 ° C for 0.5 to 12 hours to obtain the above ceramic material. Here, zeolite is SiO ₂ / Al ₂
It is a substance with an O ₃ ratio of 3.5 to 7.5. 10. A ceramic which is virtually free of cracks, has a porosity of 5% or less, and has a major crystal phase of a leucite / porcite solid solution, and xK ₂ O is an empirical formula expressed as a metal oxide. : YCs ₂ 0: zSiO ₂ : Al ₂ O ₃ . Where x is 0.01 to 0.99
, Y also varies from 0.01 to 0.99, and z varies from 3.5 to 7.5. When z is 7.5, y is larger than 0.19. This ceramic has a coefficient of thermal expansion in the range of 50 ° to 700 ° C from 2 × 10 ▲ superscript -6 ▼ to 27 × 10 ▲ superscript -6 ▼.