KR101343808B1 - Composite for low temperature sinterable porcelain and manufacturing method of low temperature sinterable porcelain - Google Patents

Abstract

wollastonite are included to the molar ration of 20:80-35:65, a sintered body has a uniformly distributed crystal phase, and the water absorption of the sintered body is equal to or less than 0.5%, and to a method for producing porcelain at low temperatures. According to the present invention, an element based on a mullite phase can be replaced with an element based on a Anorthite phase to make sintering possible at low temperatures under 1200°C. When comparing with the normal porcelain element based on a mullite phase,he element based on a Anorthite phase is fully densified, having mechanical strength suitable for being used as porcelain.

Description

Low temperature sintered porcelain composition and method for manufacturing low temperature sintered porcelain using the same {Composite for low temperature sinterable porcelain and manufacturing method of low temperature sinterable porcelain}

The present invention relates to a magnetic composition and a method of manufacturing the porcelain, and more particularly, to a porcelain based on an anthite (Anorthite) phase and a low-temperature firing porcelain composition capable of sintering at a low temperature of 1200 ° C. or lower and low calcining using the same. It relates to a manufacturing method of porcelain.

Pottery refers to a product that is cured by applying heat after molding and mixing inorganic materials such as clay, feldspar and silica. Pottery is divided into earthenware, stoneware, pottery and porcelain according to the firing temperature and physical properties. Porcelain is densified by firing in 1st and 2nd step at high temperature of 1,250 ℃ ~ 1,450 ℃ according to the characteristics The water absorption rate is classified into 0.5% or less.

The porcelain body is generally composed of 50% by weight of clay mineral (usually kaolin), 25% by weight of flux (feldspar), and 25% by weight of filler (silica). Provide (plasticity) and the quartz acts as a skeleton. In addition, the flux forms a liquid phase at a temperature lower than the melting temperature of clay or silica and serves to promote plasticity.

In porcelain, clay forms a mullite and glass phase in the substrate after firing, thereby contributing to the white light transmitting property while maintaining sufficient strength in the use environment.

Naturally produced feldspar belongs to three single-component families: potassium feldspar (KAlSi ₃ O ₈ ), soda feldspar (NaAlSi ₃ O ₈ ), and calcium feldspar (CaAl ₂ Si ₂ O ₈ ). Potassium feldspar and calcium feldspar hardly form a solid solution, but potassium feldspar and soda feldspar, and soda feldspar and calcium feldspar form a continuous solid solution. Feldspar is used as a raw material for porcelain, and dissolves clay or silica in the firing process, forming a liquid and mullite phase to act as a flux to give strength.

Silica is mainly composed of silica, so its refractory degree is SK32 ~ 35, which acts as a skeleton of the base during the forming and firing process and forms glass. When the silica is used in the base material, the whiteness and light transmittance are increased, the mechanical strength is improved, and the wear rate is decreased.

In the Samsung system of clay-feldspar-gyuseok, the temperature at which the magnetic composition is equilibrated to mullite is over 1600 ℃. Generally, however, a flux such as feldspar is used to promote the formation of the mullite phase between 1250 and 1300 ° C. to complete the sintering.

In recent years, research has been conducted to replace the base material based on the mullite phase and develop a magnetic base material which is sintered at a low temperature of 1200 ° C. or lower. The present invention relates to an anthite phase based on the mullite phase. Subsequently, the present invention proposes a magnetic composition in which sintering is performed at a low temperature of 1200 ° C. or lower as a base material.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a low temperature fired ceramic composition and a method of manufacturing a low temperature fired ceramic using the same that are used for porcelain based on an anthite (Anorthite) phase and sintered at a low temperature of 1200 ° C. or lower.

The present invention includes kaolin and wollastonite, wherein the kaolin and wollastonite have a molar ratio of 20:80 to 35:65, and the calcined body formed by firing uniformly distributes an annosite crystal phase, The absorptivity provides a low temperature firing ceramic composition exhibiting a value less than or equal to 0.5%.

The shrinkage rate of the fired body is less than or equal to 10%, and the bending strength of the fired body is higher than 70 MPa.

The low temperature fired ceramic composition may further include 0.01 to 15 parts by weight of at least one material selected from glass frit and waste glass based on 100 parts by weight of kaolin.

In addition, the low-temperature baking ceramic composition may further comprise 0.01 to 7 parts by weight of boric acid based on 100 parts by weight of the kaolin.

In addition, the low-temperature baking ceramic composition may further comprise 0.01 to 15 parts by weight of soda feldspar based on 100 parts by weight of the kaolin.

In addition, the low-temperature firing ceramic composition may further include 0.01 to 15 parts by weight of carlisle based on 100 parts by weight of the kaolin.

In addition, the present invention, (a) mixing the kaolin and wollastonite in a molar ratio of 20:80 to 35:65, (b) shaping and drying the mixed product in the desired form and (c) the dried product The step of firing at a temperature of 1000 ~ 1200 ℃ to form a porcelain, wherein the porcelain anodized crystal phase is uniformly distributed, the low-temperature calcined porcelain exhibiting the absorption rate of the porcelain is less than or equal to 0.5% Provide a method.

The shrinkage rate of the magnetism is less than or equal to 10%, and the bending strength of the magnetism is higher than 70 MPa.

In step (a), 0.01 to 15 parts by weight of one or more materials selected from glass frit and waste glass may be further mixed with respect to 100 parts by weight of kaolin.

In the step (a), 0.01-7 parts by weight of boric acid may be further mixed with respect to 100 parts by weight of the kaolin.

In the step (a), 0.01 to 15 parts by weight of soda feldspar may be further mixed with respect to 100 parts by weight of the kaolin.

In the step (a) it may be further mixed with 0.01 to 15 parts by weight of carrierite relative to 100 parts by weight of the kaolin.

According to the present invention, the base material based on the mullite phase can be replaced with the base material based on the anorthite phase, and sintering is possible at a low temperature of 1200 ° C. or lower.

In addition, according to the present invention, compared with the general magnetic material having a mullite phase, the base material based on the anosite can be sufficiently densified to have a mechanical strength suitable for use as a magnet.

1 is a graph showing the ternary system of K ₂ O—Al ₂ O ₃ —SiO ₂ .
2 is a graph showing the ternary system of CaO-Al ₂ O ₃ -SiO ₂ .
3 is a scanning electron microscope (SEM) photograph showing the microstructure of the wollastonite powder used in Example 1. FIG.
4 is a view showing a change in bending strength according to the composition change of the fired specimen prepared according to Example 1.
5 is a view showing an X-ray diffraction (XRD) pattern of the fired specimen prepared according to Example 1.
6 is a photograph of the objects produced by the injection molding method according to Example 2.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it should be understood that the following embodiments are provided so that those skilled in the art will be able to fully understand the present invention, and that various modifications may be made without departing from the scope of the present invention. It is not.

The ceramic composition for low temperature firing according to a preferred embodiment of the present invention comprises kaolin and wollastonite, wherein the kaolin and wollastonite have a molar ratio of 20:80 to 35:65, and the calcined body formed by firing is an annosite. The crystal phases are uniformly distributed, and the absorption rate of the fired body is less than or equal to 0.5% (eg, 0.2 to 0.5%).

The shrinkage rate of the fired body is less than or equal to 10% (eg, 0.7 to 10%), and the bending strength of the fired body is higher than 70 MPa (eg, 70 to 100 MPa).

The low temperature fired ceramic composition may further include 0.01 to 15 parts by weight of at least one material selected from glass frit and waste glass based on 100 parts by weight of kaolin.

In addition, the low-temperature baking ceramic composition may further comprise 0.01 to 7 parts by weight of boric acid based on 100 parts by weight of the kaolin.

In addition, the low-temperature baking ceramic composition may further comprise 0.01 to 15 parts by weight of soda feldspar based on 100 parts by weight of the kaolin.

In addition, the low-temperature firing ceramic composition may further include 0.01 to 15 parts by weight of carlisle based on 100 parts by weight of the kaolin.

According to a preferred embodiment of the present invention, there is provided a method for producing a low-temperature fired porcelain, (a) mixing kaolin and wollastonite at a molar ratio of 20:80 to 35:65, and (b) forming the mixed product into a desired shape. Drying and (c) calcining the dried product at a temperature of 1000 to 1200 ° C. to form porcelain, wherein the anosite crystal phase is uniformly distributed, and the absorptivity of the porcelain is less than 0.5%. Or the same value.

The shrinkage rate of the magnetism is less than or equal to 10%, and the bending strength of the magnetism is higher than 70 MPa.

In step (a), 0.01 to 15 parts by weight of one or more materials selected from glass frit and waste glass may be further mixed with respect to 100 parts by weight of kaolin.

In the step (a), 0.01-7 parts by weight of boric acid may be further mixed with respect to 100 parts by weight of the kaolin.

In the step (a), 0.01 to 15 parts by weight of soda feldspar may be further mixed with respect to 100 parts by weight of the kaolin.

In the step (a) it may be further mixed with 0.01 to 15 parts by weight of carrierite relative to 100 parts by weight of the kaolin.

Hereinafter, a method of manufacturing the low temperature calcined porcelain of the present invention will be described in detail.

As seen in the ternary system of the _{K 2 O-Al 2 O 3} -SiO 2 in Figure 1, the alkali (Alkali), alkaline earth (Alkali earth) except for K ₂ O Assuming that all of the K ₂ O-based oxide magnetic possession The composition of is in the region where the mullite is the main phase, the mullite phase must be present when sintering at a predetermined temperature or more. Indeed, the strength after sintering of porcelain is known to be highly dependent on the shape and amount of mullite phase present in the body, and efforts have been made to optimize the shape and amount of the mullite phase in the body.

Sequentially looking at the reaction occurring during the sintering process of the base with clay- feldspar-gyuseok, kaolin loses the crystal water at 500 ~ 600 ℃ to form metakaolin. At around 990 ° C., amorphous SiO ₂ promotes the formation of eutectic melts. Near 1075 ° C. metakaolin decomposes and begins to form primary mullite. As the sintering proceeds above 1200 ° C., the liquid phase formed in the substrate begins to saturate the SiO ₂ component, and the secondary mullite begins to grow in the region where feldspar was present. The body currently used for living magnetics is generally sintered at 1250 ° C. or higher to form a densified structure having a bulk density of 2.4 g / cm 3 or more composed of glassy, mullite and unmelted silica.

In the Samsung system of clay-feldspar-gyuseok, the temperature at which the magnetic composition is equilibrated to mullite is over 1600 ℃. Generally, however, a flux such as feldspar is used to promote the formation of the mullite phase between 1250 and 1300 ° C. to complete the sintering.

In the present invention, to replace the base material based on the mullite phase that has been used until now to develop a base material based on the anodite (Anorthite) phase sintering at a temperature of 1200 ℃ or less.

In the ternary system of CaO-Al ₂ O ₃ -SiO ₂ shown in FIG. 2, CaO, SiO ₂ , and Al ₂ O ₃ components are mixed at a ratio (molar ratio) of 1: 2: 1 and subjected to a heat treatment at a high temperature of 1200 ° C. or higher. It can be seen that the anosite phase is formed.

In previous studies, limestone could be used as a source of CaO, and kaolin and silica could be added in appropriate proportions to form an anosite phase. The problem with this method, however, is that CO ₂ and H ₂ O decompose during the heat treatment process in limestone and kaolin, resulting in high porosity. In order to solve this problem, the raw materials were micronized and densified material was obtained by using a flux such as waste glass or boric acid. However, the micronization of raw materials leaves room for various problems in the actual production process.

Therefore, in the present invention, cyano sites _{(Anorthite, CaO · 2SiO 2 ·} Al 2 O 3) kaolin for the production of the substrate for forming a crystal phase _{(Kaolinite, Al 2 O 3 ·} 2SiO 2 · 2H 2 O) and wollastonite (Wollastonite, CaOSi0 ₂ ) is used. Dense bases can be produced using wollastonite instead of limestone as a source of CaO.

Wollastonite has a larger particle size than kaolin with a particle size of 50 µm or more. The particle size distribution forming bimodal distribution with kaolin can solve problems such as abnormal shrinkage and cracking during the drying process which may occur due to differentiation. 3 shows the microstructure of the wollastonite powder used in Example 1. FIG.

Kaolin and wollastonite are mixed in a molar ratio of 20:80 to 35:65 to produce low temperature calcined porcelain. Kaolin and wollastonite are responsible for forming an anosite crystal phase in the porcelain, and the anosite crystal phase is uniformly distributed in the porcelain as a single phase in the porcelain. Thus, the porcelain in which the anosite single phase is distributed is less than 0.5%. Or the same value, the sintering temperature can be lowered to 1200 ° C or lower (eg, 1000 to 1200 ° C).

At this time, by adding glass frit, waste glass, boric acid, boric acid, soda feldspar, and feldspar together, the sintering temperature may be further lowered. The presence of minerals or additives in the substrate during the sintering process that allows the formation of liquid phases at an early time may accelerate the formation of anosite crystal phases, resulting in lowering the sintering temperature.

The at least one material selected from glass frit and waste glass is preferably mixed with 0.01 to 15 parts by weight based on 100 parts by weight of the kaolin.

It is preferable that the said boric acid mixes 0.01-7 weight part with respect to 100 weight part of said kaolins.

The soda feldspar is preferably mixed with 0.01 to 15 parts by weight based on 100 parts by weight of the kaolin.

It is preferable to mix 0.01-15 weight part of said karyorite with respect to 100 weight part of said kaolins.

The mixing may use a process such as ball milling.

The wet ball milling process is described as an example.

Kaolin and wollastonite are charged into a ball milling machine and mixed with solvents such as water and ethanol. The ball mill is rotated at a constant speed to mechanically mix the kaolin and wollastonite. The ball used for the ball milling is preferably a ceramic ball such as alumina or zirconia, and the balls may be all the same size or may be used together with balls having two or more sizes. The size of the balls, the milling time, and the rotation speed per minute of the ball miller are adjusted so as to be crushed to the target particle size. For example, in consideration of the size of the particles, the size of the balls may be set in the range of about 1 mm to 50 mm, and the rotational speed of the ball miller may be set in the range of about 50 to 500 rpm. The ball milling is preferably performed for 1 to 48 hours in consideration of the target particle size and the like. By ball milling, kaolin and wollastonite are crushed into particles of fine size and mixed with a uniform particle size distribution. As a result, the mixed product of kaolin and wollastonite, which have undergone the wet grinding process, is micronized to form a slurry.

In order to remove the iron (Fe) component contained in the slurry may be carried out a step of de-ironing with a degasser. A known method can be used for the de-ironing process, and a description thereof will be omitted here.

In addition, the slurry may be subjected to a dehydration process. The dehydration process may be performed using an extrusion filter press, or may be mixed with a refiner after dehydration treatment.

The resulting mixture of kaolin and wollastonite is shaped into the desired shape and dried. The above-mentioned molding can be variously adopted, such as injection molding, extrusion molding, etc. The drying process is preferably carried out for 2 to 72 hours at a temperature of room temperature to 150 ℃.

The dried resultant is calcined at a temperature of 1000 to 1200 캜 to form porcelain. The magnetite thus formed is uniformly distributed in the anosite crystal phase, and its absorption rate is less than or equal to 0.5%. In addition, the shrinkage rate of magnetism is less than or equal to 10%, and the bending strength of magnetism is higher than 70 MPa.

Hereinafter, the firing process will be described in detail.

The resultant mixed for the firing is charged to a furnace such as an electric furnace and the firing process is performed. The firing process is preferably performed for 10 minutes to 48 hours at a temperature of about 1000 ~ 1200 ℃. It is desirable to keep the pressure inside the furnace constant during firing.

The firing is preferably carried out at a temperature in the range of 1000 to 1200 ° C. When the firing temperature is less than 1000 ° C, the thermal or mechanical properties of the porcelain may be poor due to incomplete firing, and when it exceeds 1200 ° C, it is uneconomical due to high energy consumption.

The firing temperature is preferably raised at a heating rate of 1 to 50 ° C / min. If the heating rate is too slow, the time is long and productivity is deteriorated. If the heating rate is too high, thermal stress is applied due to a rapid temperature rise It is preferable to raise the temperature at the temperature raising rate in the above range.

The firing is preferably carried out at a firing temperature for 10 minutes to 48 hours. If the firing time is too long, it is not economical since the energy consumption is high. Further, it is difficult to expect further firing effect. If the firing time is small, the physical properties of the ceramic material may not be good due to incomplete firing.

In addition, the firing can be performed in both an oxidizing or reducing atmosphere, and there is no limitation.

After carrying out the firing process, the furnace temperature is lowered to unload the fired body. The furnace cooling may be allowed to cool down in a natural state by turning off the furnace power source, or to set a temperature drop rate (eg, 10 ° C./min) arbitrarily. The pressure inside the furnace is preferably kept constant while the furnace temperature is lowered.

The firing process may be performed as follows. After heating up to 1st temperature (700-1000 degreeC), it carries out initial firing, and after performing chaebol firing which hold | maintains for a fixed time (10 minutes-48 hours) at 2nd temperature (for example, 1000-1200 degreeC), it cools to normal temperature. It may be made of a process to. After performing the above initial firing, the chaebol firing may be performed by cooling to room temperature and raising the temperature to a second temperature (for example, 1000 to 1200 ° C).

Hereinafter, embodiments according to the present invention will be specifically shown, and the present invention is not limited to the following embodiments.

≪ Example 1 >

Kaolin and wollastonite were combined at the ratios (molar ratios) shown in Table 1 below and injection molded into rod-shaped specimens.

Furtherance Kaolin Wollastonite Sum One 47 53 100 2 37 63 100 3 28 72 100

The molded specimen was dried at room temperature and then fired in an air atmosphere using an electric furnace. The temperature was raised at a rate of 5 ° C. per minute, maintained at 1200 ° C. for 1 hour, and then cooled to obtain a fired specimen.

The fired specimens were measured for volume specific gravity and water absorption (KSL 4008) using the Archimedes method, and the shrinkage ratio (KSL 1590) was calculated by measuring the bow axis of the fired specimens. In addition, the crystal phase and the bending strength (KSL 1595) of the fired specimens by composition were measured.

Looking at Table 2 below, it can be seen that as the amount of wollastonite added in the composition increases, the volume specific gravity increases but the absorption rate decreases. It can be seen that the fired specimen using composition 3 has an absorption rate of 0.5% or less corresponding to the definition of porcelain. It can be seen that the shrinkage increases with the addition of wollastonite, but has a very low shrinkage compared to the general magnetic material (~ 14%).

Table 2 below shows the physical properties of the fired specimens.

Furtherance Volume specific gravity (g / cm 3) Absorption Rate (%) Shrinkage (%) One 1.76 18.57 0.73 2 2.13 8.83 6.17 3 2.51 0.30 9.33

Figure 4 shows the change in bending strength according to the composition change of the fired specimen prepared according to Example 1.

Referring to Figure 4, it can be seen that the addition amount of wollastonite increases and the bending strength increases. In particular, in the case of the fired specimen using the third composition, the strength is significantly increased, and the average value is 80 MPa or more. Although the standard deviation also increases, this figure indicates that the porcelain porcelain has sufficient mechanical strength. Considering the volume specific gravity, it can be seen that the mechanical strength appears due to sufficient densification of the pores. It can be seen that the anodized base also has a suitable mechanical strength when used as porcelain when sufficiently densified as compared with ordinary porcelain bodies having mullite phase.

5 is a crystalline phase according to the change in composition for the fired specimen prepared according to Example 1 was measured by X-ray diffraction (XRD) analysis. In Figure 5 (a) is the X-ray diffraction pattern of the fired specimen prepared using the composition 1 of Table 1, (b) is the X-ray diffraction pattern of the fired specimen prepared using the composition 2 of Table 1 , (c) is the X-ray diffraction pattern of the fired specimen prepared using the composition 3 of Table 1.

Referring to FIG. 5, it can be seen that the fired specimens using the second and third compositions consisted of a single phase of ananosite. However, it can be seen that cristobalite is present together with the anosite in the case of the fired specimen using the first composition. This can be seen as a result of the relatively high amount of kaolin in the starting composition. Cristobalite may cause problems such as breakage upon cooling due to high coefficient of thermal expansion, and therefore, composition 1 is not suitable as a magnetic holding composition.

<Example 2>

Kaolin and wollastonite were combined in a molar ratio of 28:72 and mixed using ball milling. At this time, in order to prevent the aggregation of kaolin and wollastonite in water and to promote uniform mixing, 0.5% water glass and sodium polyacrylate-based dispersant were added to the total content of kaolin and wollastonite.

After 12 hours of ball milling, a slurry in which impurities and aggregates were removed through a vibrating body was prepared. This slurry was directly injected into a gypsum mold to prepare a product. 6 is a photograph of the objects produced by the injection molding method.

As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to the said embodiment, A various deformation | transformation by a person of ordinary skill in the art within the scope of the technical idea of this invention is carried out. This is possible.

Claims (12)

Includes kaolin and wollastonite,
The kaolin and the wollastonite form a molar ratio of 20:80 to 35:65,
Further comprising 0.01 to 7 parts by weight of boric acid based on 100 parts by weight of the kaolin,
In the fired body formed by firing, the anosite crystal phase is uniformly distributed,
Absorption rate of the calcined body is less than 0.5%, characterized in that the magnetic composition for low-temperature firing.
The magnetic composition of claim 1, wherein the shrinkage of the fired body is less than or equal to 10% and the bending strength of the fired body is higher than 70 MPa.
The ceramic composition for low temperature firing according to claim 1, further comprising 0.01 to 15 parts by weight of at least one material selected from glass frit and waste glass, based on 100 parts by weight of kaolin.
delete The magnetic composition for low temperature firing according to claim 1, further comprising 0.01 to 15 parts by weight of soda feldspar based on 100 parts by weight of the kaolin.
The magnetic composition for low-temperature firing according to claim 1, further comprising 0.01 to 15 parts by weight of feldspar based on 100 parts by weight of the kaolin.
(a) mixing kaolin and wollastonite in a molar ratio of 20:80 to 35:65;
(b) shaping and drying the mixed result into the desired form; And
(c) calcining the dried product at a temperature of 1000 to 1200 ° C. to form porcelain,
0.01 to 7 parts by weight of boric acid is further mixed with respect to 100 parts by weight of the kaolin in step (a),
The porcelain anodized crystal phase is uniformly distributed,
The absorption rate of the porcelain is a method of producing a low-temperature fired porcelain, characterized in that less than or equal to 0.5%.
8. The method of claim 7, wherein the shrinkage rate of the porcelain is less than or equal to 10% and the bending strength of the porcelain is higher than 70 MPa.
The method of claim 7, wherein in step (a), 0.01 to 15 parts by weight of at least one material selected from glass frit and waste glass is further mixed with respect to 100 parts by weight of kaolin.
delete The method of claim 1, wherein in the step (a), 0.01 to 15 parts by weight of soda feldspar is further mixed with respect to 100 parts by weight of the kaolin.
[8] The method for manufacturing low-temperature fired porcelain according to claim 7, further comprising mixing 0.01 to 15 parts by weight of carrierite with respect to 100 parts by weight of the kaolin in the step (a).

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