JP3031872B2 - Thermal shock resistant ceramics and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal shock resistant ceramic having high durability against sudden temperature changes such as rapid heating and rapid cooling, and a method for producing the same. The present invention relates to a heat-resistant tableware or cooker suitable for heating by heating or freezing and preserving food, or a heat-resistant ceramic which can be applied as a heat-resistant industrial material having heat resistance up to high temperatures and heat shock resistance to rapid heat quenching.

[0002]

_2. Description of the Related Art Ceramics used as heat-resistant dishes or cookers or heat-resistant materials that are required to have durability against such rapid temperature changes include petalite (Li ₂ O.Al ₂ O _3. 8SiO ₂ ) crystal or spodumene (Li ₂ O.Al ₂ O ₃ .4Si)
So-called Lithia porcelain having O ₂ ) crystal as the main crystal phase,
Also cordierite _{(2MgO · 2Al 2 O 3 ·} 5Si
There is cordierite porcelain having an O ₂ ) crystal as a main crystal phase.

[0003] These Lithia porcelains are generally appropriately mixed with a water-insoluble lithium raw material obtained by mixing and calcining a petalite raw material, a kaolin raw material, a quartz raw material, lithium carbonate, quartz and kaolin, and the like. Is fired at a high temperature of 1350 ° C. or more to produce a porcelain containing petalite or spodumene crystals. This Lithia porcelain has a low coefficient of thermal expansion of 5 × 10 ⁻⁷ / ° C. or less and is extremely excellent in thermal shock resistance. However, lithium oxide is an expensive raw material, and the cost for calcination increases. In addition, the range of the firing temperature at which dense ceramics can be stably obtained is as narrow as about 10 ° C., and there is a problem that it is difficult to manufacture with good yield.

[0004] The cordierite porcelain is composed of a raw material of kaolin, talc, magnesite, and the like. The raw material cost is relatively low, but the thermal expansion coefficient is 2%.
It is about 0 × 10 ^-7 / ° C, which is slightly larger than that of Lithia porcelain. The firing temperature requires high-temperature firing of about 1350 ° C. as in the case of Lithia porcelain, and the range of appropriate firing temperature at which dense ceramics can be obtained stably is as narrow as about 10 ° C. Was.

[0005] Such conventional Lithia porcelain and cordierite porcelain are both sufficiently sintered, for example, to obtain dense ceramics having a water absorption of 3.0% or less, a high temperature of 1350 ° C or more. Baking is required. However, in the case of a baking furnace capable of such high-temperature baking, furnace construction costs and heating fuel costs are relatively high, and kiln tools such as baking shelf furnace materials, pillar furnace materials, and platen setters also use expensive materials. It has to be used and there is a problem that the operating cost increases.
In addition, since the range of appropriate firing temperature is as narrow as about 10 ° C. or less, the firing yield has to be extremely low, and it is difficult to mass-produce at low cost. Not widely available.

[0006] In order to solve the problem of high firing temperature in the above-mentioned Lithia porcelain, a base material containing petalite and kaolin, which are relatively inexpensive as raw materials, is widely used in the production of ordinary sanitary ware and tiles. A method of firing at a firing temperature of about 1150 to 1250 ° C. with a firing furnace used to obtain a thermal shock resistant ceramic has been put to practical use. The thermal shock-resistant ceramic obtained by this method has a firing temperature range of 5 at which firing shrinkage and density are stable.
0 ° C., which is a practical level of dimensional stability, and a thermal expansion coefficient of 30 × 10 ⁻⁷ / ° C. or less provides sufficient thermal shock resistance, but only a material having a water absorption of 10% or more can be obtained. It was insufficient in shrinkage, porous and poor in mechanical strength.

[0007] The porous and large water absorbing properties are improved by applying a glaze to the surface of the fired product, and the poor mechanical strength is compensated by increasing the thickness of the vessel. Then, for example, what is called "earthen pot" has been put to practical use. However, even these materials may leak from the cracks in the glaze during use, or the permeated water may expand and break during heating. It was inefficient in energy efficiency and could not be widely applied because it was used for specific cooking such as hot pot cooking in winter.

The following method has been put to practical use in order to improve such a porous problem. It is a raw material containing one or two alkali oxides of Na ₂ O and K ₂ O in addition to petalite and kaolin as raw materials, for example,
By adding an appropriate amount of feldspar, it is possible to sinter densely at a firing temperature of 1250 ° C or less, and to widen the appropriate firing temperature range, so that it can be applied to tableware and cookware other than clay pots to some extent. Became. However, in this method, it is difficult to obtain a material having a thermal expansion coefficient of 30 × 10 ⁻⁷ / ° C. or less, and the thermal shock resistance is insufficient. There has been a demand for ceramics that may be broken at the time, have a low coefficient of thermal expansion, have a wide range of appropriate firing temperature, and can be fired at a relatively low temperature.

[0009]

As described above,
Ceramics that can be widely used as tableware or cookers for thermal shock resistance have a thermal expansion coefficient of 30 × 10 ⁻⁷ / ° C. on the assumption that relatively inexpensive raw materials can be used.
To further improve the thermal shock resistance as follows, and to be able to be fired at a firing temperature of 1250 ° C. or less, which is almost the same as that of general ceramic products, to a dense body having a water absorption of 3% or less,
An important issue is that the appropriate firing temperature range is practical and wide, and the present invention provides a thermal shock resistant ceramic which solves these problems and a method for producing the same.

[0010]

Thermal shock resistance ceramic is a first invention to solve the above problems BRIEF SUMMARY OF THE INVENTION are the SiO ₂ fifty-five to seventy-three wt% oxide composition, the Al ₂ O ₃ 18~3
1 wt%, the Li ₂ O .6-3.5 wt%, the MgO 2.0 to 12 wt%, the total amount of Na ₂ O and K ₂ O 0.7
To 3.0% by weight only it contains, and as the predominant crystal phase, petalite
And one or two crystallites of spodumene and
Gillite microcrystals as essential crystals.
One or two kinds of Na ₂ O and K ₂ O between these crystal grains
Crystal or glass phase containing, and water absorption is 3% or less
And a dense sintered body substantially sintering substantially without water permeability . And
The present invention can be preferably embodied in the following modes. (1) acid
The SiO ₂ 55 to 63 wt% in product composition, the Al ₂ O ₃
21-31 wt%, the Li ₂ O 0.6-2.3 wt%,
MgO and 5.0 to 12 wt%, the total amount of Na ₂ O and K ₂ O
The thermal shock-resistant ceramic containing 0.7 to 2.5% by weight of
Cousin. (2) 63 to 73 weight of SiO ₂ in the oxide composition
%, The Al ₂ O ₃ 18 to 26 wt%, the Li ₂ O 1.5
~ 3.5 wt%, MgO 2.0 ~ 9.0 wt%, Na
_The above-mentioned amount containing 1.0 to 3.0% by weight of the total amount of ₂ O and K ₂ O
Thermal shock resistant ceramics.

Further, the method for producing a thermal shock resistant ceramic according to the second invention, which solves the above problem, is characterized in that when 20 to 40 % by weight of a kaolin raw material is blended , 25 to 60 % by weight of a lithium silicate raw material; 5-25 % by weight of feldspar raw material and 2-9 % by weight of magnesium oxide or magnesium oxide-based raw material in terms of MgO
When the raw material is blended at 40 to 60% by weight, lithium
13-45% by weight of silicate material, 0-20% by weight of feldspar material
%, Magnesium oxide or magnesium oxide-based raw material
It was blended 5 to 12% by weight in terms of MgO, mainly natural raw
And a maximum firing temperature of 125.
It is characterized by firing at 0 ° C. or less .
And, the present invention provides an oxide composition by the above calcination.
The SiO ₂ 55 to 63 wt%, the Al ₂ O ₃ 21-31
Weight%, Li ₂ O 0.6-2.3% by weight, MgO
5.0 to 12 wt%, the total amount of Na ₂ O and K ₂ O 0.7
２．５2.5 % by weight or SiO ₂ of 63-7%
3 wt%, the Al ₂ O ₃ 18 to 26 wt%, the Li ₂ O
1.5-3.5% by weight, MgO 2.0-9.0% by weight
%, The total amount of Na ₂ O and K ₂ O is 1.0 to 3.0% by weight.
Petalite and Spodju
One or two crystallites and cordierite microcrystals
Contains crystals as the main crystal phase and has a maximum coefficient of thermal expansion of 30 × 1
0 ^-7 / ° C, to form a dense sintered body.
It can be embodied in a method for producing a thermal shock resistant ceramic.

[0012]

Next, an embodiment of the thermal shock resistant ceramic of the present invention will be described. In the present invention, SiO ₂ , Al ₂ O ₃ , MgO, L
and i ₂ O, further with one or the essential components of Na ₂ O and K ₂ O, is respectively have a composition of the range. Here, the raw materials from which these oxides are derived are not particularly limited, but as described later, lithium silicate raw materials such as petalite, kaolin raw materials such as clay, and natural raw materials such as talc are preferable in terms of cost.

The oxide composition has SiO ₂ of 55 to 63.
When the weight% is, the Al ₂ O ₃ 21-31% by weight, the Li ₂ O from 0.6 to 2.3 wt%, the MgO 5.0
12%, the total amount of Na ₂ O and K ₂ O 0.7 to 2.
5 wt% comprising the composition is preferably further, SiO ₂ is 6
When the content is ₃ to 73% by weight, Al ₂ O ₃ is added to 18 to ₂ %.
6 wt%, the Li ₂ O 1.5 to 3.5 wt%, the MgO 2.0 to 9.0 wt%, the total amount of Na ₂ O and K ₂ O 1.
Compositions containing 0-3.0% by weight are also suitable.

The chemical components forming the thermal shock resistant ceramics of the present invention are not limited to the above-mentioned oxides, and other components contained in ordinary ceramics may be used as long as the effects of the present invention are not impaired. It can be included. For example, coloring metal oxide added 10 wt% or less, a small amount of CaO to be taken from natural sources, there may be TiO ₂ or other unavoidable impurities.

In the thermal shock resistant ceramic of the present invention, one or two kinds of microcrystals of petalite and spodumene, which are low thermal expansion lithium silicates, and cordierite microcrystals are used as main crystal phases. Crystals as essential crystals, and Na
A crystalline or glass phase containing one or two of ₂ O and K ₂ O is present, and is a dense sintered body substantially sintered without water permeability, sufficiently sintered to have a water absorption of 3% or less. .

As described above, the thermal shock resistant ceramics of the present invention is characterized in that the Li ₂ O component and the MgO component coexist and contains petalite crystals or spodumene crystals and cordierite crystals as main crystal phases. L
Since i ₂ O-based and MgO-based crystals have low expansion properties, in the present invention, despite containing Na ₂ O or K ₂ O,
An increase in the coefficient of thermal expansion is suppressed. And
At the grain boundaries of these low thermal expansion crystals, there exists a crystal or glass phase containing one or two of Na ₂ O and K ₂ O, and the crystal or glass phase may have a relatively low melting point. In a relatively low temperature region of the firing process, acts to promote the growth and sintering of the low thermal expansion crystal, as a result, significantly lower the firing temperature of the thermal shock resistant ceramic of the present invention, and It seems that the appropriate firing temperature range can be widened.

Particularly, in the present invention, the MgO component, which is a characteristic component, has a remarkable effect on lowering the firing temperature and expanding the appropriate firing temperature range, and is a plastic raw material indispensable for the molding step. SiO _{2 in} kaolin raw material,
The clay component containing Al ₂ O ₃ as a main component suppresses the generation of high thermal expansion mullite crystals and the like, and rather contributes to the generation of low thermal expansion cordierite crystals. It has the effect of keeping the coefficient of thermal expansion low.

Therefore, the thermal shock resistant ceramics of the present invention
As a chemical component of_Two, Al _TwoO_Three, MgO,
To approximate the composition of cordierite,_Two,
Al _TwoO_Three, Li_TwoO approximates the composition of petalite
And also SiO_Two, Al_TwoO_Three, K_TwoO, Na_Two
O is a glass or glass having an appropriate coefficient of thermal expansion and melting temperature.
Consider the content so that it has a composition that produces crystals.
It is appropriate to combine the respective components.

From this point, it is necessary to contain the MgO component in an amount of 2% or more, and if it exceeds 12%, the above effect is rather deteriorated, which is not preferable. Such Mg
When the total amount of Na ₂ O and K ₂ O is 0.8% or more in the presence of O and Li ₂ O, a dense sintered body is obtained at a firing temperature of 1250 ° C. or less while maintaining low thermal expansion. And the appropriate firing temperature range can be expanded to 40 to 50 ° C. or more. However, Na ₂ O, K ₂ O
, The baking temperature can be further lowered, but the coefficient of thermal expansion is 30 ×
When it exceeds 10 ^-7 / ° C, it becomes impractical for thermal shock applications.

Here, the thermal shock resistant ceramic of the present invention
In the most preferred embodiment, it has the oxide composition of Si
O_TwoFrom 58 to 69% by weight of Al_TwoO_ThreeIs 21-28 weight
%, Li_Two0.9 to 3.0% by weight of O and 4.0 of MgO
-10% by weight, Na_TwoO and K _TwoThe total amount of O is 0.7-2.
5% by weight, together with petalite crystals and spoju
At least one kind of iron crystal and cordierite crystal
It consists of a dense sintered body containing as a crystal phase, and has a thermal expansion coefficient of
Up to 25 × 10^-7/ ° C, appropriate firing temperature range is at least 4
A thermal shock resistant ceramic characterized by being at 0 ° C
is there. And in this thermal shock resistant ceramic,
The characteristics of the balanced thermal expansion coefficient and the appropriate firing temperature range are combined.
Ceramics with good thermal shock resistance
It can be provided under practical manufacturing conditions.

The thermal shock resistant ceramic of the present invention described in detail above can be manufactured by the above-described method of manufacturing a thermal shock resistant ceramic according to the second invention of the present invention. Here, the embodiment will be described. First, a lithium silicate raw material, for example, a petalite raw material or a spodumene raw material, and a kaolin raw material, for example, those containing a large amount of clay minerals such as frog-eye clay and kaolin clay, and a magnesium oxide-based raw material For example, in addition to talc, magnesite, and the like, MgO alone, magnesium hydroxide, or the like is used as an essential raw material.
_A base is prepared by adding feldspar containing at least one of ₂ O and K ₂ O, and blending a raw material of SiO ₂ compound, for example, a raw material such as silica stone, silica sand, and quartz. Next, the resultant article is molded and fired by a usual method to obtain the thermal shock resistant ceramic.

The kaolin raw material of the present invention is an indispensable raw material for maintaining plasticity or preventing cracks after molding when forming a blended base material, and it is necessary to contain 20% by weight or more. Then, according to the two ranges of the kaolin content of 20 to 40% by weight and 40 to 60% by weight, the preferable content of the other raw materials differs as described below.

In this case, when 20 to 40% by weight of the kaolin raw material is blended, 25 to 40% by weight of the lithium silicate raw material is used.
60 wt%, 2-9 wt% in terms of MgO as magnesium oxide based material, K ₂ O, is preferred to feldspar compounding 5-25 wt% containing either Na ₂ O, also, kaolin When the raw material is compounded in an amount of 40 to 60% by weight, 13 to 45% by weight of a lithium silicate raw material, 5 to 12% by weight of a magnesium oxide-based raw material in terms of MgO, and either K ₂ O or Na ₂ O Feldspar containing 0-20
It is preferable to mix by weight%.

The lithium silicate raw material of the present invention is a basic raw material for exhibiting a low thermal expansion property, and petalite is optimal from the viewpoint of cost. The content is 13% by weight
If it is less than 30 × 10 ⁻⁷ / ° C. or less, it is difficult to obtain one having a coefficient of thermal expansion of less than 60% by weight. From 13 to 60% by weight. Preferably, the range is 18 to 55% by weight.

Further, the present invention is characterized in that a magnesium oxide-based material such as talc is used in combination with the kaolin material and the lithium silicate material. When the kaolin raw material is fired, it generates mullite or cristobalite having a large thermal expansion coefficient, which is generally a cause of increasing the thermal expansion coefficient of the fired product. As a result, it became possible to lower the coefficient of thermal expansion rather than to generate cordierite from kaolin and the MgO component (addition of SiO _{2 as} necessary). It was also recognized that the MgO component promoted the sintering action when coexisting with petalite and the like.

As a starting material for the MgO component, talc (talc) is suitable in addition to containing an appropriate amount of SiO ₂ and cost, and when the MgO component is insufficient, magnesia, magnesite or the like is applied. It is possible that the amount of the compound is MgO corresponding to a stoichiometric amount corresponding to the production of cordierite from the kaolin raw material, but is preferably 2.0 to 12% by weight in terms of MgO.
It is preferably contained in an amount of 4 to 10% by weight.

The feldspar used in the present invention is K ₂ O, N
Orthodoxite and albite containing at least one of a ₂ O may be used. Use of this proper amount is effective in promoting the formation and sintering of the main crystal phase, and is indispensable for lowering the firing temperature to 1250 ° C or lower and expanding the appropriate firing temperature range to 40 ° C or higher. although, since the strong effect of increasing the thermal expansion coefficient, the other ingredients, but to determine the amount depending on the firing temperature of components and adopting, 0.7 as the total amount of Na ₂ O and K ₂ O In view of Na ₂ O and K ₂ O components obtained from raw materials other than feldspar, feldspar may not be particularly required to be blended, and the upper limit is suitably 25% by weight. However, the amount is preferably 1 to 20% by weight.

Here, the most preferred embodiment of the method for producing a thermal shock ceramic according to the present invention will be described. The kaolin raw material is 25 to 50% by weight, and the lithium silicate raw material is 18 to 55%.
% By weight, 1 to 20% by weight of feldspar material, and at least one of talc, magnesium hydroxide and magnesite in terms of MgO.
A method for producing a thermal shock-resistant ceramic, comprising molding a composition containing from 10 to 10% by weight and firing at a maximum firing temperature of 1250 ° C. or lower. And furthermore,
This is a production method in which such a raw material composition is fired to form the above-mentioned thermal shock-resistant ceramic. That is, in the oxide composition, SiO ₂ is 58 to 69% by weight, Al ₂
O ₃ 21 to 28 wt%, the Li ₂ O 0.9 to 3.0 wt%, the MgO 4.0-10 wt%, Na ₂ O and K ₂ O
Of 0.7 to 2.5% by weight, at least one of petalite crystals and spodumene crystals and cordierite crystals as a main crystal phase, and a coefficient of thermal expansion of at most 25 × 10 ⁻⁷ / ° C. And forming a dense sintered body having an appropriate firing temperature range of at least 40 ° C.

[0029]

Next, the present invention will be described in detail based on the test results shown in Table 1.

[Table 1]

In Table 1, those marked with an asterisk (*) indicate a comparative example, and the others indicate examples of the present invention. The chemical composition in the center column indicates the chemical component composition calculated from the raw material mixing ratio in the left column in terms of% by weight.

Here, the raw materials to be used are usually available, blended according to the raw material blending ratios in Table 1, added with an appropriate amount of water, wet-pulverized and mixed with a ball mill, dried appropriately, and then vacuum kneaded. The base was prepared by kneading with a machine. Next, a prismatic sample having a cross section of 10 × 10 mm and a length of 60 mm was prepared from this base material using a dry press molding machine, and fired to obtain a test body.

[0032] The test specimen was placed in an electric heating furnace for 11 hours.
Heat up to 200 ° C at a heating rate of 200 ° C / hr.
When the temperature is higher than 00 ° C., the heating rate is reduced to 120 ° C./hr, and the heating is performed. The temperature at which the water absorption of the sintered specimen reaches 3.0% or less is defined as the hardening temperature in Table 1. And Further, the test piece thus obtained was measured for a coefficient of linear thermal expansion by measuring a coefficient of thermal expansion in a range from room temperature to 500 ° C. using a normal tester for measuring thermal expansion. Further, when sintering was continued at a temperature exceeding the above-mentioned baking temperature ° C., the limit temperature immediately before the glass was floated on the surface of the sample was measured. An appropriate firing temperature range was set.

According to Table 1 showing the above test results, first, examples of No. 1 and No. 2 in the table are conventional general ones, which are blends using petalite and kaolin. Since a high temperature of 1340 ° C. is required and the appropriate firing temperature range is narrow, it is difficult to supply a large amount at low cost. The thermal expansion coefficient when a large amount of petalite is blended is 30
× 10 ⁻⁷ / ° C. or less, which is at a practically preferable level. However, when the firing temperature is set to about 1250 ° C., since the hardening is not sufficient as described above, there is a possibility of water leakage or insufficient strength. The use is limited.

The examples of Nos. 3 and 4 in the table are those in which feldspar is further blended with petalite and kaolin, and the firing temperature is lowered to 1250 ° C. or less and the appropriate firing temperature range is widened due to the effect of the alkali component in the feldspar. Therefore, in that respect, it is preferable for mass production.
It is difficult to reduce the temperature to 0 ⁻⁷ / ° C. or less, and it cannot be used in application fields that require more severe thermal shock resistance.

The examples of No. 5 to No. 21 in the table relate to the present invention. In addition to petalite, kaolin and feldspar, magnesium hydroxide or talc is used as a compounding raw material, and SiO ₂ , Al ₂ O ₃ is used as a chemical component. , Li ₂ O, MgO, and at least one of K ₂ O and Na ₂ O. From these results, the following was found.

(1) As exemplified in No. 3 and No. 12, and No. 4 and No. 9, petalite is made of MgO alone or M
By substituting gO and SiO ₂ , the coefficient of thermal expansion can be significantly reduced and the firing temperature can be lowered. Thus, despite the low blending amount of low thermal expansion petalite, the coefficient of thermal expansion was greatly reduced because the kaolin raw material did not generate high thermal expansion mullite or cristobalite and had low thermal expansion. This is probably due to the change to sexual cordierite.

It is generally said that cordierite is not easily synthesized in a temperature range of 1250 ° C. or less.
It is presumed that this is due to the effect of Li ₂ O, K ₂ O, and Na ₂ O which coexist simultaneously with the kaolin and MgO raw materials as in this example. The content of MgO is preferably in accordance with the reaction formula for changing the kaolin content blended into cordierite as described above, but the effect is considerably remarkable when the content is higher or lower. Yes, it is suitable in the range of 2 to 12% by weight.

(2) As the amount of Na ₂ O and K ₂ O increased, the firing temperature decreased and the appropriate firing temperature range tended to increase. However, the tendency for the thermal expansion coefficient to increase at the same time was observed. Also, as the amount of petalite increased, the coefficient of thermal expansion tended to decrease. From these, the total amount of Na ₂ O and K ₂ O is preferably in the range of 0.7 to 3.0% by weight, and Li ₂ obtained from the petalite component is preferable.
The O content is preferably in the range of 0.6 to 3.5% by weight.

(3) In the invention according to the production method of the present invention, as for the moldability at the time of molding, the kaolin raw material is 2%.
Mechanical rotomolding was possible in the range of 0 to 60% by weight, but in particular, when the wall thickness is thin, or when shrinkage cracks are liable to occur during drying such as a deep pan shape, in order to increase the drying strength, The kaolin content is preferably 25% by weight or more, more preferably 30% by weight or more.

[0040]

According to the thermal shock resistant ceramics of the present invention, since lithiasilicate and cordierite crystals, both of which have low thermal expansion, coexist, they have a dense and low thermal expansion characteristic and an appropriate amount of K _2. The present invention provides a ceramic excellent in thermal shock resistance, capable of lowering the hardening temperature to 1250 ° C. or lower due to the presence of O or Na ₂ O and widening the appropriate firing temperature range. Further, according to the manufacturing method, there is an excellent effect of providing a practical method for manufacturing a thermal shock-resistant ceramic having the above-mentioned features without using an expensive raw material such as lithium carbonate. Accordingly, the present invention has a thermal shock resistant ceramic which has solved the conventional problems and a method for producing the same, which has an extremely large industrial value.

Claims (5)

(57) [Claims] 1. An oxide composition comprising 55 to 73% by weight of SiO ₂ , 18 to 31% by weight of Al ₂ O ₃ and 0.6% of Li ₂ O.
To 3.5 wt%, the MgO from 2.0 to 12 wt%, Na ₂
The O and K ₂ the total amount of O unrealized 0.7 to 3.0 wt%, and the main
One of petalite and spodumene as crystalline phase
Or two kinds of microcrystals and cordierite microcrystals are essential
Contained as crystals, and Na ₂ O
And a crystal or glass phase containing one or two of K ₂ O
Exists and is sufficiently sintered to have a water absorption of 3% or less.
Thermal shock resistant ceramics characterized by being made of a dense sintered body that is qualitatively non-permeable . 2. An oxide composition comprising SiO _Two 55 to 63 weight
%, Al _Two O _Three 21 to 31% by weight of Li _Two O to 0.6
2.3 wt%, MgO 5.0-12 wt%, Na _Two
O and K _Two 2. The composition according to claim 1, wherein the total amount of O is 0.7 to 2.5% by weight.
Thermal shock resistant ceramics described in 1. 3. An oxide composition comprising SiO _Two The 63-73 weight
%, Al _Two O _Three From 18 to 26% by weight of Li _Two O to 1.5
~ 3.5 wt%, MgO 2.0 ~ 9.0 wt%, Na
_Two O and K _Two The total amount of O is 1.0 to 3.0% by weight.
2. The thermal shock resistant ceramic according to 1. 4. A blend of kaolin raw material in an amount of 20 to 40 % by weight .
In this case, 25 to 60 % by weight of a lithium silicate raw material, 5 to 25 % by weight of a feldspar raw material, and 2 to 9 % by weight of magnesium oxide or a magnesium oxide-based raw material in terms of MgO .
Or 40 to 60% by weight of kaolin raw material
When the lithium silicate raw material is 13 to 45% by weight,
0-20% by weight of stone material, magnesium oxide or oxidized
Contains 5-12% by weight of magnesium based material in terms of MgO
It was, molding the blend composition consisting mainly of natural sources,
A method for producing a thermal shock-resistant ceramic, comprising firing at a maximum firing temperature of 1250 ° C. or lower . 5. The method according to claim 1, wherein the sintering is performed to obtain an oxide composition of SiO 2.
_Two From 55 to 63% by weight of Al _Two O _Three The 21-31 weight
%, Li _Two 0.6 to 2.3% by weight of O and 5.0 of MgO
~ 12% by weight, Na _Two O and K _Two The total amount of O is 0.7-2.
5% by weight or SiO _Two The 63-73 weight
%, Al _Two O _Three From 18 to 26% by weight, L i _Two O to 1.5
~ 3.5 wt%, MgO 2.0 ~ 9.0 wt%, Na
_Two O and K _Two Containing 1.0 to 3.0% by weight of O
The main crystal phases are petalite and spodumene.
One or two types of microcrystals and cordierite microcrystals
Included as crystalline phase, maximum 30 × 10 ^-7 / ℃
The heat-resistant bump according to claim 4, which forms a dense sintered body that is:
Manufacturing method of hammering ceramics.