JP2016002572A - Slurry composition for manufacturing precision casting mold and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a slurry composition for manufacturing a precision casting mold which satisfies both of a viscosity required for slurry and refractory characteristics and, further, facilitates the formation of a uniform slurry coating layer, in the slurry composition for manufacturing the precision casting mold constituted by using mullite-base refractory powder as aggregate, and to provide a method capable of advantageously manufacturing the slurry composition for manufacturing the precision casting mold excellent in such characteristics.SOLUTION: A slurry for manufacturing a precision casting mold is constituted by suspending powder of mullite-base refractory as aggregate into a binder composition prepared by compounding bentonite to an inorganic binder made of colloidal silica or ethyl silicate.

Description

  TECHNICAL FIELD The present invention relates to a slurry composition for producing a precision casting mold and a method for producing the same, and in particular, a slurry composition that can be suitably used in molding a precision casting mold by the lost wax method, and industrially advantageous. It relates to a method of manufacturing.

  Conventionally, in the molding of precision casting molds by the lost wax method, first, a wax mold (wax mold) having a shape corresponding to a product shape is obtained with a slurry containing a binder in which fine particle aggregates (filler materials) are suspended. After coating the surface of the model) to form a slurry layer, a stucco material is sprayed on the surface of the slurry layer and dried to form a first ceramic shell layer on the surface of the wax mold, Thereafter, the second ceramic shell layer is formed by coating with the slurry again and spraying the stucco material on the formed slurry layer. Then, by repeating such an operation a plurality of times, a plurality of ceramic shell layers are formed, and then the wax mold is removed by heating and melting, and further fired so that the desired precision casting mold is manufactured. It has become. The casting is obtained by casting a predetermined molten metal (molten high-temperature metal material) into the cavity of the mold from which the wax mold has been removed.

  In addition, when forming a precision casting mold by such a lost wax method, as an aggregate of slurry generally used, zircon fine powder, silica fine powder, alumina fine powder, mullite fine powder, etc. are known, Among them, fine powder of zircon has been widely used together with zircon grains as stucco materials (edited by the Japan Foundry Association Precision Casting Research Group, “Precision Casting”, Nikkan Kogyo Shimbun, published in January 1984, Pages 31-36 and JP-A-61-289944).

In particular, among these aggregates, zircon grains and fine powder of zircon are difficult to react with high-temperature molten metal and are difficult to cause insertion into castings, so that a beautiful cast skin can be easily obtained. In addition, since the thermal expansion is relatively small, it has a feature that the dimensional accuracy of the resulting casting is good, but because of its large specific gravity, the weight of the mold obtained by molding becomes heavy. Because it is difficult to produce large cast products and complex shaped products, it is not naturally produced in large quantities and its production area is unevenly distributed, so it will be used as a mold material in the future. May become difficult. Furthermore, since zircon grains and zircon fine powders have ZrO ₂ and SiO ₂ as chemical components, control of the chemical composition between the Al ₂ O ₃ components commonly used as stucco materials is possible. As a result, it is difficult to reuse the used mold, and in addition, since the radioactive material is contained in a trace amount, there is a problem that the disposal is expensive.

  Therefore, in order to solve such a problem, a casting mold for precision casting that does not use zircon grains or fine zircon powder has been proposed. For example, Japanese Patent Laid-Open Nos. 2005-324253 and 2003-225739 In the examples, mullite grains or alumina grains are used. Further, even in the applicant of the present application, in JP 2013-75312 A and JP 2013-75313 A, as aggregate, mullite grains, alumina grains, or a mixture thereof is used as a binder. It is clarified that a ceramic shell layer is formed by using a slurry mixed with colloidal silica.

  By the way, in the slurry obtained by blending such a fire-resistant aggregate (filler material) with an inorganic binder such as colloidal silica (for forming a primary layer or a backup layer in a precision casting mold) Viscosity has been controlled by the type and amount of fine powder, but viscosity control is not possible at the amount required when mullite refractory powder is used as such a refractory aggregate. This is possible and inherently required at a blending ratio, the viscosity becomes too low, and the problem that the slurry characteristics cannot be maintained is inherent.

  Specifically, as an aggregate serving as a slurry base material, a powder made of mullite-based refractory is mixed with a binder such as colloidal silica to form a slurry having a viscosity suitable for application to a brazing mold surface. Then, from the beginning of the blending, the binder composition to which the mullite refractory powder has been added becomes a highly viscous material, and there is a problem that it becomes extremely difficult to prepare a slurry having the desired viscosity. In addition, in a range where the viscosity as a slurry can be secured, the binder composition formed by mixing the mullite refractory powder when the blending ratio of the mullite refractory powder is reduced and added to the binder. When the viscosity of the binder composition decreases over time and becomes a stable viscosity, the viscosity of such a binder composition becomes too low, the applicability to the wax model deteriorates, and uniform coating and a predetermined thickness are achieved. As a result, it is difficult to apply the coating material, which causes a serious problem in practical use.

JP 61-289944 A JP 2005-324253 A JP 2003-225739 A JP2013-75312A JP 2013-75313 A

Edited by Japan Foundry Association, Precision Casting Research Group, “Precision Casting”, published by Nikkan Kogyo Shimbun, January 1984, pages 31-36

  Here, the present invention has been made in the background of such circumstances, and the problem to be solved is for the production of precision casting molds formed using mullite refractory powder as an aggregate. In the slurry composition, it is intended to achieve both the viscosity and refractory properties required as a slurry, and to facilitate the formation of a uniform slurry coating layer, and to produce precision casting molds excellent in such properties. It is providing the method which can manufacture the slurry composition for water advantageously.

  And in the present invention, in order to solve the above-mentioned problem or the problem grasped from the description of the entire specification, it can be suitably implemented in various aspects as listed below. Each aspect described below can be employed in any combination. It should be noted that aspects or technical features of the present invention are not limited to those described below, and can be recognized based on the description of the entire specification or the inventive idea disclosed therein. Should be understood.

(1) A slurry comprising a mullite refractory powder suspended as an aggregate in a binder composition obtained by blending bentonite with an inorganic binder made of colloidal silica or ethyl silicate. A slurry composition for producing precision casting molds.
(2) The said bentonite is contained so that it may become a ratio of 0.1 to 2 weight% with respect to the total amount of the said inorganic binder and the said mullite type refractory powder. Slurry composition for precision casting mold manufacturing.
(3) The mullite-based refractory according to the aspect (1) or the aspect (2), wherein the mullite-based refractory has a chemical composition composed of 45 to 85% by weight of Al ₂ O ₃ , the balance being SiO ₂ and impurities. Slurry composition for precision casting mold manufacturing.
(4) The said aspect (1) thru | or the said aspect (3) in which the powder of the said mullite type refractory is used in the ratio of 1.5 to 2.2 times on a weight basis with respect to the said inorganic binder. The slurry composition for precision casting mold manufacture as described in any one of these.
(5) After blending bentonite with an inorganic binder made of colloidal silica or ethyl silicate to prepare a binder composition, mullite-based refractory powder is added as an aggregate to the binder composition. A method for producing a slurry composition for producing a precision casting mold, wherein the slurry is made into a slurry by suspending.
(6) The precision casting mold according to the aspect (5), wherein the bentonite is blended in the inorganic binder, and then held for 30 minutes or more with stirring, and then the mullite refractory powder is added. A method for producing a slurry composition for production.

  As described above, in the slurry composition for producing a precision casting mold according to the present invention, a binder composition obtained by blending bentonite with an inorganic binder made of colloidal silica or ethyl silicate is used, and mullite is used as an aggregate. By suspending the refractory powder to form a slurry, a ceramic shell layer having good refractory properties can be advantageously formed for the first time while ensuring the viscosity required for the slurry. It was.

  Further, according to the method for producing a slurry composition for producing a precision casting mold according to the present invention, bentonite is pre-blended with an inorganic binder, and then the mullite-based refractory as an aggregate for the obtained binder composition. By allowing the powder to suspend and disperse, the viscosity required as a slurry can be advantageously realized without increasing or decreasing the amount of aggregate. Without blending the powder until the initial viscosity becomes extremely high, it is possible to advantageously obtain a slurry having a viscosity necessary for application to the wax model at a blending ratio at which the refractory characteristics can be sufficiently exhibited. It became.

  By the way, as an inorganic binder which is one of the components of the slurry composition for producing precision casting molds according to the present invention, a slurry conventionally used for forming a ceramic shell layer in the lost wax method (investment method). Various known colloidal silicas or ethyl silicates that give Moreover, what mix | blended media, such as water and alcohol, with such an inorganic binder as needed can be used advantageously.

  As the colloidal silica as the inorganic binder, those in which ultrafine amorphous silica having a particle diameter of about 3 to 200 nm is stably dispersed in a dispersion medium are generally used. Among these, as such colloidal silica, silica sol having a silica particle diameter of about 3 to 30 nm and dispersed at a concentration of about 20 to 40% by weight is particularly preferably used. Further, as ethyl silicate, tetraethyl orthosilicate, ethyl silicate 40, ethyl silicate 28, or the like is preferably used.

In addition, the bentonite which is blended in such an inorganic binder and constitutes the binder composition contains a clay mineral montmorillonite as a main component and a silicate mineral such as quartz as a minor component, as well known, and further includes feldspar, etc. Silicate minerals, carbonate minerals such as calcite, sulfate minerals, sulfide minerals and other weak alkaline claystones, which have the property of absorbing water and swelling in water. It is rich in metal ions and alkaline earth metal ions. Specifically, those classified into alkaline bentonite and alkaline earth bentonite are used, and generally, by containing a large amount of alkali metal, sodium bentonite (Na-bentonite), when containing a large amount of alkaline earth metal, calcium -It is called bentonite (Ca-bentonite). Such bentonite, SiO ₂ amount of the main component is in the range of 60 to 80 wt%, _{other, Al 2 O 3, Fe 2} O 3, Na 2 O, K 2 O, CaO, contain MgO or the like Yes.

Further, in the slurry composition for producing a precision casting mold according to the present invention, the mullite refractory powder used as an aggregate (filler material) is mainly composed of mullite crystals or a mixed crystal of mullite and corundum. In general, what is artificially obtained by mixing and firing an Al ₂ O ₃ source material and an SiO ₂ source material is used, but it is also a natural product. Can be used as well.

Here, it is difficult to uniquely limit the composition of such a mullite-based refractory, but in the present invention, it contains 45 to 85% by weight of Al ₂ O ₃ , and the balance is those having a chemical composition consisting of SiO ₂ and impurities, and thus preferably used. Further, the content of the remaining SiO ₂ is generally about 15 to 55% by weight, and impurities made of other oxides are about 5% by weight or less. Such mullite refractories are used as powders, and specifically, are used as powders of 100 μm or less, preferably 50 μm or less.

  And, when producing a slurry composition for precision casting mold production according to the present invention, first, a predetermined amount of bentonite is blended with the inorganic binder composed of the colloidal silica or ethyl silicate, and sufficiently stirred. By being dispersed, the binder composition is prepared. The amount of bentonite used here is appropriately selected according to the viscosity of the finally obtained slurry composition, but is generally 0 with respect to the total amount of inorganic binder and mullite refractory powder. .1 to 2% by weight, preferably about 0.25 to 1% by weight. When the amount of bentonite used is reduced, there is a problem that it is difficult to sufficiently exert the effect of addition, and when the amount used is excessive, the viscosity of the binder composition increases, and the intended slurry composition There is a risk of causing problems that make it difficult to manufacture.

  In addition, such bentonite is blended by adding bentonite little by little under stirring of an inorganic binder for its uniform dispersion or distribution, and after completion of addition of such bentonite, The obtained binder composition is desirably held for at least 30 minutes while continuing the stirring. By holding for such a predetermined time, bentonite can be effectively dispersed and present in the binder composition, and the object of the present invention can be advantageously achieved.

  Then, a predetermined slurry composition is formed by adding a predetermined amount of mullite-based refractory powder as an aggregate and suspending the resulting binder composition while stirring it. However, such a mullite refractory powder is not added at a time, but is added in small amounts over time to the binder composition, and stirred to be uniformly dispersed. It is done. The viscosity of the slurry composition thus prepared increases immediately after the addition of the mullite refractory powder, but under stirring, the slurry viscosity decreases with the passage of time. After 24 hours, a slurry viscosity with a B-type viscometer viscosity of 250 cps or more and a Zahn cup # 5 measurement value of 13 seconds or more can be realized continuously for 4 days or more. A long slurry composition can be obtained.

  The amount of the mullite refractory powder added to the binder composition as described above is appropriately selected for effective formation of the target ceramic shell layer. On the basis of weight, it is used in a ratio of 1.5 to 2.2 times, preferably 1.7 to 2.1 times. If the blending amount of this mullite refractory powder becomes too large, the viscosity of the system will increase extremely at the initial blending stage with respect to the binder composition, and further blending may become difficult. If the amount is too small, problems such as difficulty in forming a uniform ceramic shell layer and difficulty in imparting the desired fire resistance may occur.

  By the way, for the slurry composition according to the present invention thus obtained, various surfactants are used as necessary, as in the case of known slurries conventionally used in the lost wax method (investment method). Or a gelation accelerator or the like is appropriately contained.

  Then, using the slurry composition according to the present invention thus obtained, a primary layer in a precision casting mold is formed in the same manner as in the prior art, and further on (behind) such a primary layer. A backup layer is formed. That is, in the production of a precision casting mold using the slurry composition according to the present invention, the tree (wax mold) dipped in such a slurry composition is lifted from the slurry composition, and then this is taken. A predetermined stucco material is sprinkled (stucked) before the slurry composition that adheres the tree and does not dry out. In addition, when the stucco material is sprinkled, any conventionally known sprinkling method is appropriately selected. For example, a drop-type sprinkling method (rain sander method) in which sprinkling is performed by dropping the stucco material in a rainy state. The stuccoing is carried out using the solid flow ascending method, in which the tree is housed in a container and the stucco material is floated or flowed by the air blown out from the bottom of the container. It is.

The stucco material used here can be appropriately selected from known materials. For example, in addition to natural refractory particles such as zircon sand, alumina sand, and silica sand, JP2013-75312A. Apparent porosity composed of Al ₂ O ₃ : 50 to 95% by weight, SiO ₂ : 5 to 50% by weight and other oxides: 0 to 15% by weight as disclosed in Japanese Patent Application Laid-Open No. 2013-75313, etc. Spherical refractory particles having an Al content of less than 5%, Al ₂ O ₃ : 40 to 70% by weight, SiO ₂ : 30 to 60% by weight, and other oxides: an apparent porosity of 5 to 14 % Of porous spherical refractory particles or the like will be used. In particular, the stucco material used to form the innermost layer in contact with the molten metal during casting that constitutes the primary layer has an influence on the adhesion and the smoothness of the casting surface. From the point of causing defects such as leakage, the particle diameter is preferably about 0.05 mm to 0.4 mm, preferably about 0.1 to 0.3 mm without a corner, and further, the material is Artificial spherical particles such as mullite, corundum and mullite / corundum having high heat resistance and good thermal expansion characteristics are preferably used.

  After that, the first ceramic shell layer (primary layer) which becomes the innermost layer is obtained by subjecting the tree (wax type) coated with the slurry composition or sprinkled with the stucco material to natural drying or mechanical drying. ) Is formed. Then, according to the ceramic shell mold method, a plurality of series of shell layer forming steps including dipping, stuccoing, and drying are further performed in the same manner as described above on the solder mold in which the first ceramic shell layer is formed. A plurality of ceramic shell layers (overall thickness: about 3 to 10 mm) are laminated on the wax mold by repeating the times (about 4 to 10 times). In these multiple ceramic shell layers, the first and second ceramic shell layers are generally called primary layers, and the third and subsequent ceramic shell layers are called backup layers. ing. And especially the slurry composition according to this invention will be advantageously used for formation of such a primary layer, Of course, it can be used also for formation of a backup layer. In addition to the slurry composition according to the present invention, a known slurry can be used for forming the backup layer. Further, as the stucco material used for forming the backup layer, refractory particles having a particle size larger than that of the stucco material used for forming the primary layer, for example, about 0.2 to 3 mm are generally employed. It will be.

  Next, the plurality of ceramic shell layers laminated on the tree (wax mold) in this way are heated to a temperature of about 120 to 150 ° C. in an autoclave to melt and remove the wax mold. The plurality of ceramic shell layers from which the brazing mold has been removed are fired in a firing furnace at a temperature of about 800 to 1200 ° C. for 30 minutes to 120 minutes. A hollow precision casting mold having a mold wall made of a binder) is obtained.

  Then, when producing a casting using the precision casting mold produced as described above, the desired casting is obtained by pouring a predetermined molten metal into the cavity of the casting mold formed by removing the wax mold. However, the casting method of such a casting is not limited in any way, and conventionally known methods such as the pouring method, the reverse pressure method, the suction casting method, and the centrifugal casting method are known. Any of these methods is advantageously used.

  Thereafter, the cast casting is subjected to mold release after the molten metal has solidified. This mold release is processed with a knock-out machine to remove the casting mold from the casting, and further, shot blasting treatment and / or sand blasting treatment is performed to remove the casting mold attached to the casting skin, and the casting skin is removed. Preparation is done. On the other hand, for castings with high corrosion resistance to acids and alkalis, such as castings of stainless steel and heat-resistant steel, including holes and slits, the mold is chemically disintegrated and removed after treatment with a knockout machine, Thereafter, shot blasting and / or sandblasting is performed. Thus, the desired precision casting is obtained.

  The preferred embodiments of the present invention have been described in detail above, but these are merely examples, and the present invention is interpreted in a limited manner by the specific description according to such embodiments. It should be understood that it is not.

  For example, the inorganic binder and bentonite constituting the precision casting mold manufacturing slurry composition according to the present invention, and mullite refractory powders are all commercially available, and in the present invention, These commercially available products can be appropriately selected and combined to form the intended slurry composition.

  In manufacturing the precision casting mold described above, a large number of product wax molds having a target casting shape are prepared, and an appropriate number of the product wax molds prepared are used as a gate, a runner, and a weir part. The produced tree (wax mold or wax model) is used by assembling together with the mold-type wax mold, but it is just a precision casting mold for one product wax mold as described above. It is also possible to manufacture one of the desired precision castings by casting.

  Examples of the present invention will be shown below to clarify the present invention more specifically. However, the present invention is not limited by the description of such examples. Needless to say. In addition to the following examples, in addition to the specific description described above, the present invention includes various changes, modifications, and modifications based on the knowledge of those skilled in the art without departing from the spirit of the present invention. It should be understood that improvements and the like can be added.

  First, a commercially available colloidal silica (US: Ransom & Randolph product; Prime Coat) in liquid form is prepared as an inorganic binder, and a commercially available synthetic mullite powder (Itochu Ceratech Co., Ltd. product) is used as the mullite refractory powder. MM, -325 mesh), and a commercially available bentonite product (Hojun product; Hodaka) was prepared as the bentonite.

  Next, 750 parts by weight of colloidal silica and a predetermined amount of bentonite are placed in a bottomed cylindrical stainless steel container having a diameter of 140 mm, and stirred for 1 hour at a rotation speed of 200 to 250 rpm using a stirring blade of 70 mmφ. Retained. Here, the amount of bentonite used is 0%, 0.25%, 0.50%, 0.75%, or 1.00% on a weight basis with respect to the total amount of colloidal silica and synthetic mullite powder described below. It set so that it might become a ratio. Then, 1500 parts by weight of the synthetic mullite powder was added little by little over 15 minutes while continuing the stirring, and the mixture was slowly mixed. In addition, the rotation speed of the stirring blade was gradually increased so as not to involve air, and was increased up to 600 to 720 rpm. Then, after all 1500 parts by weight of the synthetic mullite powder was added and mixed, the mixture was held for 10 minutes as it was, then the number of rotations was lowered to 450 rpm, and then stirred and held at 450 rpm, whereby various slurry compositions (A To E).

  The slurry compositions (A to E) with different bentonite addition amounts thus obtained are each kept under stirring, and the Zahn cup viscosity is set immediately after the preparation until the viscosity stabilizes. Measurements were made to examine changes in the viscosity (viscosity) of the respective slurry compositions. The Zahn cup viscosity was determined as the Zahn cup viscosity by using # 5 manufactured by Bokel Co., Ltd., and measuring the time until no dripping of the slurry occurred. Further, after each slurry composition was stabilized (after 48 hours had elapsed from the time of preparation), the viscosity was measured with a B-type viscometer to determine the B-type viscosity. And while showing the result of the viscosity change accompanying the elapsed time from the slurry preparation time of the Zahn cup viscosity about each slurry composition in the following Table 1, after performing the preparation about each slurry composition, slurry viscosity The Zahn cup viscosity and B-type viscosity were measured after 48 hours from the preparation time at which the solution became stable.

  For comparison, a slurry composition is used in the same manner as described above by using kaolin, which is one of the same clays as bentonite, at a ratio of 1.00% (22.5 parts by weight) instead of bentonite. (F) is prepared, and further zircon powder is used as an aggregate, and 3200 parts by weight thereof is blended with 800 parts by weight of colloidal silica to prepare the same slurry composition (G) as in the past. As for the slurry compositions (F, G), the Zahn cup viscosity and the B-type viscosity were measured in the same manner as described above, and are shown in Table 1 and Table 2 below.

  As apparent from the results of Tables 1 and 2, according to the present invention, the slurry viscosity is effective for the slurries B to E prepared by using the binder composition obtained by adding bentonite to colloidal silica. It is recognized that a slurry viscosity similar to that of the conventionally used slurry G can be realized with a small amount of mullite powder used.

  On the other hand, in the slurry A which is a slurry composition not containing bentonite, the amount of mullite powder used is small, so that the slurry viscosity becomes too low and it is difficult to form an effective ceramic shell layer. In addition, in the slurry F which is a slurry composition in which kaolin is mixed instead of bentonite, the viscosity of the slurry cannot be sufficiently increased, and the slurry A in which bentonite is not mixed It was revealed that the slurry viscosity was comparable.

  Moreover, after the viscosity of each of the various slurry compositions A to G prepared above was stabilized, a plate retention test using a metal plate of 75 mm × 75 mm × 1 mm, width: 25 mm, thickness: 5 mm And a wax mold adhesion test using a wax mold having a length of 75 mm. The immersion depth in each slurry composition of the wax type was 50 mm. And the plate and wax type | mold immersed in each slurry composition were pulled up, the adhesion amount of the slurry composition after 1 minute, 30 minutes, and after drying was calculated | required, and the result was shown in following Table 3.

  From the results shown in Table 3, in the slurry compositions B to E containing bentonite according to the present invention, the amount of adhesion to the plate and the wax mold increases, and the amount of adhesion equivalent to that of the conventional slurry composition G. It is recognized that it is possible to realize On the other hand, in the case of the slurry composition A containing no bentonite or the slurry composition F using kaolin, which is not bentonite, the amount of the slurry composition adhering to the plate or the wax mold is small. Therefore, it is recognized that it is difficult to form an effective ceramic shell layer, and the adhesion state of A and F of these slurry compositions is uneven and has a rough uneven surface in visual observation. It was possible to see a plate or wax-type substrate.

  Furthermore, using the slurry compositions A and B prepared above, each of the trees attached with a predetermined wax mold was applied as a primary slurry in the same manner as in the past. Was insufficient in the amount of slurry adhered, and it was difficult to adhere stucco material (Celabead # 950, manufactured by ITOCHU CERATECH CORPORATION) to the wax mold. However, when the slurry composition B containing bentonite is applied, a sufficient amount of slurry can be secured, and stucco material (Celabead # 950, manufactured by ITOCHU CERATECH Co., Ltd.) can be adhered. In addition, the second layer could be laminated in the same manner. The third and subsequent ceramic shell layers can also be effectively realized as a backup layer by forming in the same manner as before, and thereafter, drying, dewaxing, and firing are performed as in the conventional case. As a result, the target mold for precision casting was obtained.

Claims (6)

  Precision characterized by suspending mullite refractory powder as an aggregate to a binder composition in which bentonite is blended with an inorganic binder made of colloidal silica or ethyl silicate to form a slurry. A slurry composition for producing casting molds.   The said bentonite is made to contain so that it may become a ratio of 0.1 to 2 weight% with respect to the total amount of the said inorganic binder and the said mullite type refractory powder. Slurry composition. The mullite refractories, 45-85 wt% Al ₂ O ₃ and the balance precision casting mold forming slurry composition according to claim 1 or claim 2 has a chemical composition consisting of SiO ₂ and impurities object.   4. The powder according to claim 1, wherein the mullite refractory powder is used in a ratio of 1.5 to 2.2 times based on weight with respect to the inorganic binder. 5. A slurry composition for the production of precision casting molds.   After blending bentonite with an inorganic binder made of colloidal silica or ethyl silicate to prepare a binder composition, a mullite refractory powder is added to the binder composition as an aggregate and suspended. A method for producing a slurry composition for producing a precision casting mold, wherein the slurry is made into a slurry by caulking. 6. The slurry composition for producing a precision casting mold according to claim 5, wherein the bentonite is blended in the inorganic binder, and is then held for 30 minutes or more under stirring, and then the mullite refractory powder is added. Manufacturing method.