JP2014177358A - Manufacturing method of unglazed porcelain with use of shell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an unglazed porcelain having a surface with a color denatured by firing, with use of shell only.SOLUTION: A greenware formed of porcelain raw material with or without contacting shell disposed in a furnace is heated to 900°C and held at the temperature for several tens of minutes. Heating is then stopped and the furnace is cooled. The unglazed porcelain taken out from the furnace is disposed in a furnace and heated to 1300°C in an oxidizing or reducing atmosphere and held at the temperature for several tens of minutes. Heating is then stopped and the furnace is cooled. Such a manufacturing method produces a porcelain having a color denatured by firing.

Description

  The present invention relates to a manufacturing method in which only a shell is used and a color of kiln modulation appears on the surface of a ceramic without glazing.

  In Bizen ware, which produces a color called kiln change on the surface of ceramics without glazing, ceramics in an unglazed state are made by using a climbing kiln and firing for a long time using a large amount of wood as fuel. Yes. The surface of Bizen ware taken out from the climbing kiln exhibits various colors depending on the ash and flame of wood or the change of atmosphere in the kiln.

  On the other hand, in Patent Document 1, a firing space surrounded by a sheath made of a heat-resistant material is formed on the workpiece placement floor in the firing furnace, and charcoal is disposed in at least a part of the firing space; and , Placing the unglazed workpiece on the workpiece placing floor, and placing the shell in close proximity to and at least part of the periphery of the unglazed workpiece so as to be non-contact with the outer peripheral surface of the unglazed workpiece, The inside of the firing furnace is heated from room temperature to about 900 ° C. to 950 ° C. in an oxidizing atmosphere for 4 to 8 hours, and then heated to about 1250 ° C. in a reducing atmosphere for about 3 hours to 4 hours, Maintain for 1 to 2 hours, then slowly cool to 1150 ° C. over about 20 to 30 minutes in a reducing atmosphere, and maintain the state at about 1100 to 1170 ° C. for about 1 hour before heating. Pottery to stop By adopting the firing method, it is shown that the use of a large amount of wood and the long firing time required for firing ceramics in a climbing kiln can be reduced, and the same color as Bizen ware can be obtained. ing.

JP 2007-55874 A

However, since it is indispensable to use charcoal in the method of Patent Document 1, it is necessary to form a coal bed layer in the lower part of the unglazed workpiece. Therefore, the method of Patent Document 1 is shown below. It has potential technical challenges.
(1) Costs due to the use of charcoal and labor are required to form a coal bed layer, and carbon dioxide, which is one of the global greenhouse gases, is emitted by the combustion of charcoal. Furthermore, (2) when heating at about 1250 ° C., it is necessary to put the unglazed workpiece, charcoal and shells in the sheath, and in that case, it is indispensable not to contact the outer peripheral surface of the unglazed workpiece. Therefore, a relatively large sheath is required to fire one unglazed workpiece, occupying a wide space in the furnace, and therefore, the number of ceramics that express the color of the kiln modulation by one heat treatment is as follows: Compared to the case of heat treatment without using a sheath, the amount is at least half.
Due to the factors (1) and (2), the fuel cost occupies the manufacturing cost of one unglazed workpiece, and the price of the baked product is increased.

  Therefore, the present invention provides a method for producing ceramics that uses only shells without using charcoal, and that develops the color of the kiln modulation without glazing, and the properties of the shell and the color of the kiln modulation appear. By examining the temperature in detail, it is an object of the present invention to reduce the manufacturing cost of a ceramic that efficiently heats and exhibits a kiln modulation color.

  In the first aspect of the present invention, a raw material formed from a ceramic raw material or an unglazed ceramic, or a raw material formed from a ceramic raw material and an unglazed ceramic are placed in a sheath made of a heat-resistant material. After placing the shell so that it does not come into contact with or covering the sheath, the shell is heated to a temperature in the vicinity of 600 ° C. to 1000 ° C. in an oxidizing or reducing atmosphere in a heating furnace, and at that temperature for an arbitrary time. Cool after holding. After cooling, only the unglazed ceramics taken out from the heating furnace are heated in an oxidizing or reducing atmosphere in a heating furnace to a temperature in the vicinity of 1100 ° C. to 1300 ° C., held at the same temperature for an arbitrary time, and then cooled. This is a method for producing a ceramic.

  According to a second aspect of the present invention, a raw material formed from a ceramic raw material or an unglazed ceramic, or a raw material formed from a ceramic raw material and an unglazed ceramic are placed in a sheath made of a heat-resistant material. After placing the shell so that it does not come into contact with the sheath and covering the sheath, it is heated in an oxidizing or reducing atmosphere in a heating furnace to a temperature in the vicinity of 1100 ° C to 1300 ° C, kept at the same temperature for an arbitrary time, and then cooled. This is a method for producing ceramics.

  A third aspect of the present invention is the method for manufacturing a ceramic according to the first aspect and the second aspect, wherein the sheath is not covered.

  According to a fourth aspect of the present invention, there is provided a method for producing ceramics, characterized in that, in the first and second aspects, no sheath is used.

  In the fifth aspect of the present invention, the shell used in the first to fourth aspects is either a solid shape, a shape subjected to a pulverization treatment, or a shape formed after the pulverization treatment. The method for producing ceramics is characterized by using a shell made of oyster, shijimi, turban shell, abalone or the like in which calcium carbonate as a main component is present.

  A sixth aspect of the present invention is characterized in that, in the first aspect to the fourth aspect, a raw material or unglazed ceramic made by molding a ceramic raw material with a glaze applied to a part of its surface is used. This is a method for producing ceramics.

  In the seventh aspect of the present invention, the temperature is raised from 1100 ° C. to near 1300 ° C. in an oxidizing atmosphere or reducing atmosphere in a firing furnace, held at the same temperature for an arbitrary time, and then lowered to an arbitrary temperature up to 1000 ° C. It is a method for producing ceramics, characterized in that it is held for an arbitrary period of time or lowered at an arbitrary cooling rate.

  According to the present invention, it is possible to produce ceramics having various colors by using only shells without using charcoal, and without glazing, and as a result, reduce the cost by using charcoal and form a coal bed layer. Reduction of carbon dioxide, one of the global greenhouse gases generated by the combustion of charcoal, and a relatively large pod for firing one unglazed workpiece It has succeeded in achieving the unexpected effect that it is not necessary. Furthermore, since the main component of the shell used is calcium oxide by heat treatment, it can be reused as a glaze raw material even though it contains trace amounts of impurities, resulting in zero emissions. It is a success.

It is the schematic of the state which has arrange | positioned the powder (3) and the shape | molded container (4) which crushed the shell in the sheath (1) which consists of a heat insulating material, and the lid | cover (2). In the sheath (1) made of heat insulating material, the powder (3) obtained by pulverizing the shell and the molded vessel (4) are placed, the shell (6) is placed on the vessel, and the lid (2) is placed. It is the schematic of the state which carried out. It is the schematic of the state which arrange | positioned the shell (6) and the shape | molded container (4) alternately in the sheath (1) which consists of heat insulating materials, and was covered. It is the schematic of the state which has arrange | positioned the container (4) shape | molded in the bowl (8) shape | molded using the crushed shell in the sheath (1) which consists of heat insulating materials, and the lid (2). .

The best method for firing ceramics is to place a raw material that has only been dried after molding the ceramic raw material in a sheath made of refractory material, and place a powdered oyster shell around it, With the lid on, heat to 900 ° C. in an oxidizing atmosphere in an electric furnace. After holding at 900 ° C. for 30 minutes, heating is stopped and the furnace is cooled to room temperature. Next, a ceramic called unglazed state taken out from the sheath is placed in an electric furnace, heated to 1280 ° C. in an oxidizing atmosphere or a reducing atmosphere, held at 1280 ° C. for 30 minutes, and then the heating is stopped and allowed to cool naturally. .
EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to an Example.

  The dried oyster shell was pulverized to about 5 to 10 mm using a jaw crusher, and then powdered using a crusher. This powder was placed in a deep ceramic container and placed in a sheath made of heat-resistant material. In the vicinity, a vessel was placed after molding clay for Iwamiyaki and dried, and then the lid was covered. A cross-sectional image in this state is shown in FIG.

  Put the powder of the oyster shell and the sheath containing the vessel into an electric furnace, raise the temperature from room temperature to 900 ° C. for 9 hours in an oxidizing atmosphere, hold the temperature at 900 ° C. for 30 minutes, and then stop heating. Naturally cooled.

  The vessel taken out from the pod was placed in an electric furnace, heated for about 15 hours from room temperature to 1280 ° C. in an oxidizing atmosphere, held at 1280 ° C. for 30 minutes, and then the heating was stopped and allowed to cool naturally.

  The outside of the vessel taken out of the electric furnace had a reddish brown color, indicating a kiln modulated color like Bizen ware.

  The dried oyster shell was pulverized to about 5 to 10 mm using a jaw crusher, and then powdered using a crusher. This powder was placed in a deep ceramic container and placed in a sheath made of heat-resistant material. Around that area, a vessel molded with clay for Iwami-yaki was heat-treated at 900 ° C., and a vessel called unglazed was placed. Furthermore, after placing the raw oyster shell so as to cover the upper part of the vessel, the sheath was covered. A cross-sectional image in this state is shown in FIG.

  Put the oyster shell powder and the sheath containing the vessel in an electric furnace, raise the temperature from room temperature to 1280 ° C in an oxidizing atmosphere for about 15 hours, hold at 1280 ° C for 30 minutes, and then stop heating. Naturally cooled.

  The outside and inside of the vessel taken out from the pod were colored reddish brown, indicating kiln-modulated color like Bizen ware.

  In a sheath made of a heat-resistant material, after placing the clay and the oyster shells that were dried after molding clay for Iwami-yaki, the sheaths were covered. A cross-sectional view of this state is shown in FIG.

  Put the pod with the container and oyster shells alternately stacked in an electric furnace, raise the temperature from room temperature to 900 ° C. in an oxidizing atmosphere, take 9 hours, hold at 900 ° C. for 30 minutes and heat Stopped and allowed to cool naturally.

  Although there were cases where oyster shells were attached to a part of the surface of the vessel taken out from the pod, most of the portions were not attached with oyster shells and could be removed. The vessel was placed in an electric furnace, and the temperature was raised from room temperature to 1280 ° C. in an oxidizing atmosphere for about 15 hours. After holding at 1280 ° C. for 30 minutes, heating was stopped and the mixture was allowed to cool naturally.

  The surface of the vessel taken out from the electric furnace had a reddish brown color, indicating a kiln modulated color like Bizen ware.

  The dried oyster shell was placed in a sheath made of heat-resistant material as it was without being processed. A vessel molded with clay for Iwami-yaki was heat-treated at 900 ° C. around the vessel, and a vessel called unglazed was placed, and then the lid was covered.

  The oyster shell and the sheath containing the vessel were placed in an electric furnace and subjected to the following three heat treatments. (1) It took 8 hours from room temperature to 800 ° C. in an oxidizing atmosphere, and after holding for 30 minutes, the heating was stopped and allowed to cool naturally. (2) It took 8.5 hours to heat from room temperature to 850 ° C. in an oxidizing atmosphere. After holding for 30 minutes, the heating was stopped and the mixture was allowed to cool naturally. (3) It took 9 hours from room temperature to 900 ° C. in an oxidizing atmosphere, and after holding for 30 minutes, the heating was stopped and the mixture was allowed to cool naturally.

  Place the vessel after three heat treatments in an electric furnace, raise the temperature from room temperature to 1280 ° C for about 15 hours in an oxidizing atmosphere, hold the temperature at 1280 ° C for 30 minutes, stop heating, and let it cool naturally did.

  The external appearance of the three types of containers taken out from the electric furnace is slightly reddish brown on the outside of the case in the case of (1) above, and in the order of the case of (3) in the case of (2) above. Became thicker.

  The dried oyster shell was placed in a sheath made of heat-resistant material without processing. A vessel molded with clay for Iwami-yaki was heat-treated at 900 ° C. around the vessel, and a vessel called unglazed was placed, and then the lid was covered.

  Put the oyster shell and the sheath containing the vessel in an electric furnace, heat in an oxidizing atmosphere from room temperature to 900 ° C for 9-10 hours, hold at 900 ° C for 30 minutes, stop heating, Allowed to cool.

  The vessel taken out from the pod was placed in an electric furnace, heated from room temperature to 1280 ° C. in a reducing atmosphere, held at the same temperature for 30 minutes, then stopped and allowed to cool naturally.

  The external appearance of the vessel taken out of the electric furnace was dark brown and a typical Bizen ware color.

The dried oyster shell was pulverized to about 5 to 10 mm using a jaw crusher, and then powdered using a crusher. A small amount of tap water was added to this powder to form a bowl shape. A container molded with clay for Iwami-yaki was placed in a sheath made of heat-resistant material, and the container was covered with rice cake molded with oyster shell powder, and then the sheath was covered. Note that the vessel and the bowl are not brought into contact with each other. A cross-sectional view of this state is shown in FIG.

  Put the vessel and the pod with the porridge covering it into an electric furnace, heat from room temperature to 900 ° C. in an oxidizing atmosphere for 9-10 hours, hold at 900 ° C. for 30 minutes, and then stop heating Naturally cooled.

  The vessel taken out from the pod was placed in an electric furnace, heated from room temperature to 1280 ° C. in an oxidizing atmosphere, held at the same temperature for 30 minutes, then stopped and allowed to cool naturally.

  The inside and outside of the vessel taken out of the electric furnace had a reddish brown color, indicating a kiln-modulated color like Bizen ware.

  After drying, the shiney husks from Shimane Prefecture were not processed and placed in a sheath made of heat-resistant material. A vessel molded with clay for Iwami-yaki was heat-treated at 900 ° C. around the vessel, and a vessel called unglazed was placed, and then the lid was covered.

  The sheath containing the husk and the vessel is put in an electric furnace, and it takes 9 hours from room temperature to 900 ° C. in an oxidizing atmosphere. After holding at 900 ° C. for 40 minutes, heating is stopped, Allowed to cool.

  The vessel taken out from the pod was placed in an electric furnace, and the temperature was raised from room temperature to 1280 ° C. for about 15 hours in an oxidizing atmosphere. After holding at 1280 ° C. for 30 minutes, heating was stopped and the mixture was allowed to cool naturally.

  The outside of the vessel taken out of the electric furnace had a reddish brown color, indicating a kiln modulated color like Bizen ware.

  The dried oyster shell was pulverized to about 5 to 10 mm using a jaw crusher, and then powdered using a crusher. A slurry-like liquid obtained by adding a small amount of tap water to this powder was applied to the inside and the outside of the vessel in a state called unglazed and dried.

  Next, after putting the vessel glazed in an electric furnace, it was heated to 1280 ° C. in an oxidizing atmosphere for 14 hours, held at 1280 ° C. for 30 minutes, and then the heating was stopped and the furnace was cooled to room temperature.

  Inside the vessel taken out from the electric furnace, a white film whose main component is calcium oxide is fixed to the oyster shell by heating. It looked like this.

  When the peeled film on the outside of the vessel was removed, the outside of the vessel turned reddish brown, indicating a color of kiln modulation like Bizen ware. It was difficult to remove the white film because the white film reacted with the vessel and stuck inside. Therefore, the vessel could not be used.

Oyster shells and shiitake shells collected in Shimane Prefecture were subjected to thermal analysis in an oxidizing atmosphere and a reducing atmosphere. Under the oxidizing atmosphere, the temperature at which the decomposition of calcium carbonate, which is the main component of shells, started at around 615 ° C. It was confirmed that the temperature at which the decomposition was completed was around 800 ° C. Further, a weight loss of about 4% was confirmed between 800 ° C. and 900 ° C. for oyster shells, and a very small weight loss between 800 ° C. and 900 ° C. was confirmed for shijimi shells. Between 900 ° C. and 1200 ° C., there was almost no weight loss in both the oyster shell and the crepe shell. On the other hand, under a reducing atmosphere, the temperature at which the decomposition of calcium carbonate, which is the main component of the shell, starts at about 640 ° C. for both oyster shells and shiitake shells, and the temperatures at which the decomposition is completed differ, 825 ° C. and 815 ° C., respectively. It was confirmed that it was in the vicinity. Further, a weight loss of about 4% was confirmed between 825 ° C. and 920 ° C. for oyster shells, and a very small weight loss between 815 ° C. and 920 ° C. was confirmed for shijimi shells. Between 920 ° C. and 1200 ° C., almost no weight loss occurred in both the oyster shell and the crepe shell.

  From the experimental results of Example 4 and the results of thermal analysis of Example 9, it is considered that the substance that contributes to the expression of the color of the kiln modulation is emitted from the shell at a temperature range of at least 800 to 900 ° C. .

  An example of the result of analyzing the red-brown area on the surface of the vessel and the area of the substrate of the cross section that appears by cutting the vessel using an electron microscope (SEM) and an energy dispersive X-ray detector (EDS) It is shown in 1.

  It was found that the substrate was mainly composed of Si and Al and composed of a compound containing a small amount of K and Fe. On the other hand, in the reddish brown region of the surface of the vessel, Mg that was not detected on the substrate was detected at a relatively high concentration, and the concentration of Si decreased, and the concentrations of Al, K, and Fe increased relatively. . From these results, it is not possible to find out what compound shows reddish brown, but Mg is considered to be one element involved in reddish brown color development.

  Next, Table 2 shows the results of analysis using an oyster shell fluorescent X-ray apparatus that was heated at 900 ° C. for 30 minutes in Example 4. From this analysis result, it was found that the oyster shell contained Mg, and when considered together with the result of the thermal analysis, Mg carbonate was decomposed simultaneously with the decomposition of calcium carbonate occurring between about 600 ° C. and about 900 ° C. It seems that sublimation occurred and adhered to the vessel placed around the oyster shell.

  Furthermore, (1) Oyster shell that was heated at 800 ° C. for 30 minutes, (2) Oyster shell that was heated at 850 ° C. for 30 minutes, and (3) 900 ° C. for 30 minutes. Each of the heated oyster shells is analyzed using an X-ray diffractometer, and the main component of (1) and (2) is calcium carbonate, and the main component of (3) is calcium oxide. found. It is considered desirable to perform heat treatment with the vessel at a temperature above the temperature at which calcium carbonate, the main component of the shell, changes to calcium oxide.

  In this specification, the heating time or holding time is specified as “arbitrary time”, but this is because the color of the kiln modulation of the finally obtained ceramic varies depending on the length of the heating time or holding time. In addition, the specific “arbitrary time” has a technical meaning because it is an arbitrary time because it can provide a unique color of kiln modulation according to the difference. There is nothing to be limited.

  Iwami-yaki, which is made in the Iwami area of Shimane Prefecture, has a history of nearly 250 years and is made mainly from locally collected clay and natural glaze ingredients. The present invention can express a kiln-modulated color not found in Iwami-yaki by using a gas furnace or an electric furnace without using a climbing kiln. Therefore, the unglazed ceramic produced by the manufacturing method of the present invention is named “Miyaki Yaki”, providing a new color and manufacturing method not found in conventional Iwami Yaki, and promoting its use.

DESCRIPTION OF SYMBOLS 1 Sheath which consists of heat insulation materials 2 Lid lid which consists of heat insulation materials 3 Powdery shells 4 Raw material or unglazed ceramics which made ceramic raw materials 5 Ceramic containers 6 Raw shells 7 Ceramic jigs 8 Powders Bowl-shaped bowl formed by mixing shaped shells

Claims (8)

  Place the raw material molded ceramic raw material, unglazed ceramic, or raw material molded ceramic raw material and unglazed ceramic, arrange shells so that they do not contact or contact these, and heat furnace In an oxidizing atmosphere or a reducing atmosphere, the mixture is heated to a temperature of 600 ° C. to 1000 ° C., preferably 800 ° C. to 1000 ° C., more preferably 850 ° C. to 950 ° C., held at the same temperature for an arbitrary time, and then cooled. After cooling, the unglazed ceramics taken out from the heating furnace are heated to a temperature of 1100 ° C to 1350 ° C, preferably 1150 ° C to 1300 ° C, more preferably 1200 ° C to 1300 ° C in an oxidizing or reducing atmosphere in the heating furnace. And cooling after holding at the same temperature for an arbitrary time.   Place raw material formed from ceramic raw material, unglazed ceramic, or raw material formed from ceramic raw material and unglazed ceramic, arrange shells so that they do not come into contact with them, and oxidize in a heating furnace. A ceramic that is heated in a reducing atmosphere to a temperature of 1100 ° C. to 1350 ° C., preferably 1150 ° C. to 1300 ° C., more preferably 1200 ° C. to 1300 ° C., held at the same temperature for an arbitrary time, and then cooled. Production method.   3. The method for manufacturing ceramics according to claim 1, further comprising a step of covering the sheath made of a heat-resistant material after placing the shell.   The method for producing a ceramic according to claim 1 or 2, wherein the raw material formed from the ceramic raw material, the unglazed ceramic, the raw raw material formed from the ceramic raw material and the unglazed ceramic, and the shell are: A method for producing ceramics, characterized by being placed in a sheath made of a heat-resistant material.   The method for producing a ceramic according to any one of claims 1 to 4, wherein the shell has a solid shape, a shape subjected to a pulverization process, a shape formed after the pulverization process, and a combination thereof. A method for producing ceramics, comprising using a shell selected from the group consisting of calcium carbonate as a main component of the shell.   The method for manufacturing a ceramic according to any one of claims 1 to 4, comprising a raw material formed from a ceramic raw material in which a glaze is applied to a part of the surface or a ceramic in an unglazed state. A method for producing ceramics.   5. The method for producing a ceramic according to claim 1, wherein the furnace is 1100 ° C. to 1350 ° C., preferably 1150 ° C. to 1300 ° C., more preferably 1200 ° C. in an oxidizing or reducing atmosphere in a heating furnace. After cooling to a temperature of 1300 ° C and holding at that temperature for an arbitrary period of time, natural cooling by stopping the heating, cooling at a cooling rate of 30 ° C or less per minute, or up to 1000 ° C A method for producing a ceramic, characterized in that the ceramic is kept at an arbitrary temperature for an arbitrary time.   A ceramic produced by the method according to any one of claims 1 to 8.