A manufacturing process for an impeller-type shell

Abstract

The present application belongs to the technical field of investment casting, and particularly relates to a manufacturing process of a impeller shell. The manufacturing process of the impeller shell comprises the following steps: 1) preparing a wax mold; 2) preparing a surface layer shell; 3) preparing a back layer shell; 4) sealing the shell with slurry; 5) dewaxing; and 6) baking. The manufacturing process of the impeller shell has the characteristics of short production cycle, low production cost, good shell removal, high finished product rate and the like, and improves the casting quality of the castings containing the impeller with a runner width less than 4 mm in the production of the casting industry.

Description

Technical Field

[0001] This invention belongs to the field of investment casting technology, and specifically relates to a manufacturing process for an impeller housing. Background Technology

[0002] Investment casting is a liquid forming process and a near-net-shape forming technology with high raw material utilization. It is also known as precision casting or lost-wax casting. Due to its high dimensional accuracy, good surface quality, applicability to complex shapes, flexible production batches, and applicability to a variety of alloys, it has been widely used in the precision forming of difficult-to-machine parts and complex thin-walled parts in the fields of automobiles, aerospace, military industry, and medical devices.

[0003] Investment casting involves creating a precisely dimensional mold from a simple, easily fusible material. A refractory material is then applied to the upper surface of the mold as needed. After standing and allowing the refractory material to dry and harden, the mold is demolded to form a shell. This shell is then fired to form a shell with a certain structural strength before pouring the casting. After cooling, the casting is obtained. The preparation of the shell is the most crucial part of investment casting. The shell, used in lost-wax casting, consists of a binder, refractory material, and auxiliary materials.

[0004] The impeller is one of the main components of a pump and plays a crucial role. Due to the complex spatial curved surface structure of the impeller flow channel and the varying widths of the channels, the manufacturing of the impeller shell is challenging. The conventional preparation process for the impeller casting mold shell involves using mullite powder for the backing layer and silica sol or water glass as a binder. In narrower flow channels, sealing with slurry or direct sand plugging is used. Cooling is performed in a reducing atmosphere during casting, requiring sand embedding and mold sealing. Furthermore, narrower flow channels often merge after four or five layers, resulting in a thicker shell in these areas. Under normal firing temperatures, this can lead to incomplete firing. Because copper alloys have low casting temperatures, when used to cast copper impellers, the shell can adhere to the cast model, making shell cleaning very difficult. However, to ensure thorough firing of thicker sections, the firing time must be extended, resulting in resource waste and potentially causing shell deformation and other problems.

[0005] Chinese invention patent CN109202019A discloses a forming process for casting closed impellers, including the following steps: mold making, surface shell making, slurry pouring, back shell making, dewaxing, firing, casting, cleaning, and heat treatment. This forming process improves the forming quality of closed impellers with flow channel widths of 4mm-15mm and diameters greater than 120mm in the casting industry; it increases production efficiency, reduces production costs, and promotes the advancement and development of precision casting closed impeller production technology. However, certain difficulties remain in producing impellers with flow channel widths less than 4mm. Summary of the Invention

[0006] In order to overcome the above-mentioned shortcomings of the existing technology, the purpose of this invention is to provide a manufacturing process for an impeller housing.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A manufacturing process for an impeller housing includes the following steps:

[0009] 1) Making wax mold: Pour wax paste into the impeller mold, wait for it to cool and solidify to form a melt pattern, and then assemble and bond the melt pattern to obtain the impeller wax mold;

[0010] 2) Preparation of surface shell: Clean and dry the impeller wax mold, then immerse the wax mold in the surface slurry, take it out and evenly sprinkle a layer of 80-120 mesh zircon sand, let it dry naturally at room temperature and blow off the loose sand. Repeat step 2) to prepare a two-layer shell for later use.

[0011] 3) Preparation of back shell: Immerse the above surface shell into the back slurry, then take it out and sprinkle sand. After drying naturally at room temperature, blow off the loose sand. Repeat step 3) to obtain two back shells for later use.

[0012] 4) Shell sealing: Immerse the above-mentioned back shell into the sealing slurry, then take it out and let it dry naturally at room temperature to complete the sealing.

[0013] 5) Dewaxing: Place the mold shell after sealing into a dewaxing kettle for high-pressure steam dewaxing, and remove it after dewaxing;

[0014] 6) Firing: Place the dewaxed shell into a firing furnace for firing. After firing, cool it to room temperature with the furnace and remove it to obtain the impeller shell.

[0015] As a preferred embodiment of the above technical solution, in step 2), the surface slurry comprises a binder and 300-325 mesh zircon powder in a weight ratio of 1:(3-4). Preferably, the surface slurry further comprises 0.1-0.3% by weight of a wetting agent and 0.1-0.3% by weight of a defoamer. The wetting agent is a vinyl alkyl alcohol ether, and the defoamer is n-octanol.

[0016] In the above technical solution, adding wetting agents and defoamers to the surface slurry can reduce the surface tension of the slurry, improve the interlayer adhesion between the slurry and the wax mold, and at the same time reduce the porosity of the surface layer, reduce the generation of defects, and improve the quality of the shell.

[0017] As a preferred embodiment of the above technical solution, in step 3), when the width of the flow channel inside the mold shell is less than 4 mm, the back layer slurry is composed of a binder and graphite sand in a weight ratio of 1:(1-2), and the sand used for sprinkling is graphite sand; when the width of the flow channel inside the mold shell is greater than or equal to 4 mm, the back layer slurry is composed of a binder and mullite powder in a weight ratio of 1:(1-2), and the sand used for sprinkling is mullite sand.

[0018] In the above technical solution, different types of materials are used depending on the width of the flow channels inside the shell. Compared with the prior art, which uses the same type of material for the shell back layer regardless of the width of the flow channels, this invention uses graphite sand for narrow flow channels and mullite powder for wide flow channels. This is mainly because: 1) Graphite sand is grayish-black and soft. Artificial graphite formed by pressure is harder, with a specific gravity of 1.9 to 2.3 and a melting point as high as 3850±50℃. Its main characteristic is high temperature resistance. Even under ultra-high temperature arc burning, the weight loss is very small, and the coefficient of linear expansion is very small (2×10). -6 Mullite powder, being 1 / 4 the size of fused alumina and 2 / 5 the size of zircon, exhibits high thermal shock resistance and minimal volume change during sudden temperature changes. Therefore, the use of graphite sand in the mold shell of this invention will not cause cracks, reducing the probability of shrinkage cracking in the product. Furthermore, mullite powder is cheaper than graphite sand, and this invention uses graphite sand only in narrow flow channels. This shortens the mold shell firing time, ensures mold shell quality, and reduces production costs.

[0019] As a preferred embodiment of the above technical solution, in step 4), the sealing grout is composed of a binder and a refractory material in a weight ratio of 1:(1.2-2). The refractory material is one or both of graphite sand and mullite powder. Preferably, the refractory material is a mixture of graphite sand and mullite powder in a weight ratio of (0.6-1):(0.6-1).

[0020] In the above technical solution, graphite sand and mullite powder are used together as refractory materials. This is mainly because there are two materials in the back shell. If only a single material is used during grouting, cracks may occur at the junction of the wide and narrow channels in the back layer due to differences in material properties, affecting the integrity of the entire shell. Therefore, this invention mixes graphite sand and mullite powder in the grouting layer, which can effectively avoid cracks at the junction caused by differences in material properties and improve the quality of the shell.

[0021] As a preferred embodiment of the above technical solution, the binder is one of silica sol and water glass.

[0022] As a preferred embodiment of the above technical solution, in step 5), the dewaxing process parameters are: pressure 0.6~0.75MPa, temperature 150~170℃, and time 6~10min.

[0023] As a preferred embodiment of the above technical solution, in step 6), the calcination process parameters are: temperature 800–900℃, heating rate 3–8℃ / min, and holding time 1.5–3h. Preferably, the calcination process parameters are: temperature 850℃, heating rate 5℃ / min, and holding time 2h.

[0024] In summary, the present invention has the following beneficial effects:

[0025] 1. The mold shell prepared using graphite sand in this invention, compared with the mold shell prepared using mullite sand in the prior art, has the advantage of preventing external oxygen from being trapped outside due to the presence of graphite sand. This eliminates the need for sand-buried cooling boxes and allows for direct air cooling without the boxes, significantly reducing the operational difficulty in the smelting workshop. Furthermore, the isolation of external oxygen from the mold shell creates a favorable protective reducing atmosphere for the molten metal, effectively preventing oxidation and the formation of pits and craters, thus improving the quality of the impeller casting. In addition, the use of graphite sand in the mold shell helps reduce its residual strength, improves its release properties, and enhances processing efficiency in post-processing.

[0026] 2. In this invention, different back layer slurries are used in the back layer according to different flow channel widths, which can not only shorten the shell firing time and reduce the shell firing temperature, but also ensure the shell quality and reduce the probability of product shrinkage cracking.

[0027] 3. In this invention, graphite sand and mullite powder are mixed in the sealing layer as a refractory material, which can effectively avoid cracks at the joint caused by differences in material properties and improve the quality of the shell.

[0028] 4. The impeller shell manufacturing process of the present invention has the characteristics of short production cycle, low production cost, good shell removal and high yield, which improves the quality of castings containing impellers with a flow channel width of less than 4 mm in the casting industry. Detailed Implementation

[0029] The technical solution of the present invention will be further described below with reference to specific embodiments. However, the specific details of the embodiments are only for illustrating the present invention and do not represent all technical methods under the concept of the present invention. Therefore, they should not be construed as limiting the overall technical solution of the present invention.

[0030] The impeller molds used in the following embodiments and comparative examples of the present invention are impeller molds of the same size and model.

[0031] Example 1

[0032] A manufacturing process for an impeller housing includes the following steps:

[0033] 1) Pour wax paste into the impeller mold, let it cool and solidify to form a melt pattern, and then assemble and bond the melt pattern to obtain the impeller wax model;

[0034] 2) Clean and dry the impeller wax mold, then immerse the wax mold in the surface slurry. After taking it out, sprinkle a layer of 100-mesh zircon sand evenly. After drying naturally at room temperature, blow off the loose sand. Repeat step 2) to prepare a two-layer shell for later use.

[0035] The surface slurry comprises silica sol and 300-mesh zircon powder in a weight ratio of 1:3, and also includes 0.2% ethylene alkyl alcohol ether and 0.2% n-octanol by weight of the slurry.

[0036] 3) Immerse the above-mentioned surface shell into the back layer slurry, then take it out and sprinkle sand. After drying naturally at room temperature, blow off the loose sand. Repeat step 3) to obtain two back layer shells for later use.

[0037] When the width of the flow channel inside the shell is less than 4 mm, the back layer slurry is composed of silica sol and 60-mesh graphite sand in a weight ratio of 1:1.6, and the sand used for sprinkling is 60-mesh graphite sand.

[0038] When the width of the flow channel inside the shell is greater than or equal to 4 mm, the back layer slurry is composed of silica sol and 200-mesh mullite powder in a weight ratio of 1:1.6, and the sand used for sprinkling is 60-mesh mullite sand.

[0039] 4) Immerse the above-mentioned back shell into the sealing slurry, then remove it and allow it to dry naturally at room temperature to complete the sealing process;

[0040] The sealing slurry is composed of silica sol, graphite sand and mullite powder in a weight ratio of 1:0.7:0.7.

[0041] 5) Place the mold shell after sealing into a dewaxing kettle for high-pressure steam dewaxing, and remove it after dewaxing; the dewaxing process parameters are: pressure 0.7MPa, temperature 160℃, time 8min;

[0042] 6) Place the dewaxed shell into a baking furnace for baking. After baking, cool it to room temperature with the furnace and remove it to obtain the impeller shell. The baking process parameters are: temperature 850℃, heating rate 5℃ / min, and holding time 2h.

[0043] In Example 1, 50 iron alloy impellers and 50 copper alloy impellers were cast from the mold shells, and all of them were qualified. During the shell cleaning process, the mold shells in the flow channel were easily removed.

[0044] Example 2

[0045] A manufacturing process for an impeller housing includes the following steps:

[0046] 1) Pour wax paste into the impeller mold, let it cool and solidify to form a melt pattern, and then assemble and bond the melt pattern to obtain the impeller wax model;

[0047] 2), Clean and air dry the impeller wax mold, then immerse the wax mold in the surface layer slurry. After taking it out, evenly sprinkle a layer of 80-mesh zircon sand, naturally dry it at room temperature, and blow off the floating sand. Repeat the operation of step 2) to prepare two layers of surface layer shells for standby;

[0048] The surface layer slurry is composed of silica sol and 300-mesh zircon powder in a weight ratio of 1:3.5.

[0049] 3), Immerse the above surface layer shell in the backing layer slurry, then take it out and sprinkle sand. Naturally dry it at room temperature and blow off the floating sand. Repeat the operation of step 3) to obtain two layers of backing layer shells for standby;

[0050] When the width of the runner in the shell is less than 4 mm, the backing layer slurry is composed of silica sol and 60-mesh graphite sand in a weight ratio of 1:1.6, and the sand for sand sprinkling is 60-mesh graphite sand.

[0051] When the width of the runner in the shell is greater than or equal to 4 mm, the backing layer slurry is composed of silica sol and 200-mesh mullite powder in a weight ratio of 1:1.6, and the sand for sand sprinkling is 60-mesh mullite sand.

[0052] 4), Immerse the above backing layer shell in the sealant layer slurry, then take it out and naturally dry it at room temperature to complete the sealing;

[0053] The sealant layer slurry is composed of silica sol, graphite sand and mullite powder, and their weight ratio is 1:0.7:0.7.

[0054] 5), Put the shell after completing the sealing into a dewaxing kettle for high-pressure steam dewaxing, and take it out after dewaxing; among them, the process parameters of dewaxing are: pressure 0.65 MPa, temperature 170 °C, time 6 min;

[0055] 6), Put the dewaxed shell into a roasting furnace for roasting, cool it to room temperature with the furnace after completion, and take it out to obtain an impeller shell; among them, the process parameters of roasting are: temperature 900 °C, heating rate 8 °C / min, holding time 1.5 h.

[0056] The shells manufactured in Example 2 were used to cast 50 ferroalloy impellers and 50 copper alloy impellers respectively. Except for a small amount of pitting on the surface of 1 ferroalloy impeller, the rest were all qualified. During the shell shaking and sand cleaning process, the shell in the runner was also very easy to remove. It is speculated that the small amount of pitting on the surface of this 1 impeller may be due to the fact that wetting agents and defoaming agents were not used in the surface layer slurry, which may lead to a relatively high surface tension of the slurry, insufficient adhesion between the slurry and the wax mold, increased porosity, and thus a small amount of defects would be generated, affecting the product quality.

[0057] Example 3

[0058] A manufacturing process for an impeller housing includes the following steps:

[0059] 1) Pour wax paste into the impeller mold, let it cool and solidify to form a melt pattern, and then assemble and bond the melt pattern to obtain the impeller wax model;

[0060] 2) Clean and dry the impeller wax mold, then immerse the wax mold in the surface slurry. After taking it out, evenly sprinkle a layer of 120-mesh zircon sand. After drying naturally at room temperature, blow off the loose sand. Repeat step 2) to prepare a two-layer shell for later use.

[0061] The surface slurry comprises silica sol and 300-mesh zircon powder in a weight ratio of 1:4, and also includes 0.1% ethylene alkyl alcohol ether and 0.3% n-octanol by weight of the slurry.

[0062] 3) Immerse the above-mentioned surface shell into the back layer slurry, then take it out and sprinkle sand. After drying naturally at room temperature, blow off the loose sand. Repeat step 3) to obtain two back layer shells for later use.

[0063] When the width of the flow channel inside the shell is less than 4 mm, the back layer slurry is composed of silica sol and 60-mesh graphite sand in a weight ratio of 1:1.8, and the sand used for sprinkling is 60-mesh graphite sand.

[0064] When the width of the flow channel inside the shell is greater than or equal to 4 mm, the back layer slurry is composed of silica sol and 200-mesh mullite powder in a weight ratio of 1:1.8, and the sand used for sprinkling is 60-mesh mullite sand.

[0065] 4) Immerse the above-mentioned back shell into the sealing slurry, then remove it and allow it to dry naturally at room temperature to complete the sealing process;

[0066] The sealing layer slurry is composed of silica sol and mullite powder in a weight ratio of 1:1.4.

[0067] 5) Place the mold shell after sealing into a dewaxing kettle for high-pressure steam dewaxing, and remove it after dewaxing; the dewaxing process parameters are: pressure 0.7MPa, temperature 160℃, time 8min;

[0068] 6) Place the dewaxed shell into a baking furnace for baking. After baking, cool it to room temperature with the furnace and remove it to obtain the impeller shell. The baking process parameters are: temperature 850℃, heating rate 5℃ / min, and holding time 2h.

[0069] In Example 3, 50 iron alloy impellers and 50 copper alloy impellers were cast from the mold shells. One iron alloy impeller and one copper alloy impeller had surface cracks, while the remaining impellers were all qualified. During the shell cleaning process, the mold shells in the flow channel were easily removed. It is speculated that the cracks leading to product defects may be due to the use of a single mullite powder as the refractory material, which may not completely eliminate the performance differences caused by the backing material, resulting in hidden cracks. During casting, the cracks were amplified by the high temperature, thus adversely affecting the impeller quality.

[0070] Example 4

[0071] A manufacturing process for an impeller housing includes the following steps:

[0072] 1) Pour wax paste into the impeller mold, let it cool and solidify to form a melt pattern, and then assemble and bond the melt pattern to obtain the impeller wax model;

[0073] 2) Clean and dry the impeller wax mold, then immerse the wax mold in the surface slurry. After taking it out, sprinkle a layer of 100-mesh zircon sand evenly. After drying naturally at room temperature, blow off the loose sand. Repeat step 2) to prepare a two-layer shell for later use.

[0074] The surface slurry comprises silica sol and 325-mesh zircon powder in a weight ratio of 1:3.2, and also includes 0.3% ethylene alkyl alcohol ether and 0.1% n-octanol by weight of the slurry.

[0075] 3) Immerse the above-mentioned surface shell into the back layer slurry, then take it out and sprinkle sand. After drying naturally at room temperature, blow off the loose sand. Repeat step 3) to obtain two back layer shells for later use.

[0076] When the width of the flow channel inside the shell is less than 4 mm, the back layer slurry is composed of silica sol and 60-mesh graphite sand in a weight ratio of 1:1.2, and the sand used for sprinkling is 60-mesh graphite sand.

[0077] When the width of the flow channel inside the shell is greater than or equal to 4 mm, the back layer slurry is composed of silica sol and 200-mesh mullite powder in a weight ratio of 1:1.2, and the sand used for sprinkling is 60-mesh mullite sand.

[0078] 4) Immerse the above-mentioned back shell into the sealing slurry, then remove it and allow it to dry naturally at room temperature to complete the sealing process;

[0079] The sealing layer slurry is composed of silica sol and graphite sand in a weight ratio of 1:1.4.

[0080] 5) Place the mold shell after sealing into a dewaxing kettle for high-pressure steam dewaxing, and remove it after dewaxing; the dewaxing process parameters are: pressure 0.7MPa, temperature 160℃, time 8min;

[0081] 6), Put the above dewaxed mold shell into a roasting furnace for roasting, and after completion, cool it to room temperature with the furnace and take it out to obtain an impeller mold shell; among them, the technological parameters of roasting are: temperature 850 °C, heating rate 5 °C / min, and heat preservation time 2 h.

[0082] The mold shells manufactured in Example 4 were used to cast 50 ferrous alloy impellers and 50 copper alloy impellers respectively. Among them, 1 ferrous alloy impeller and 1 copper alloy impeller had cracks on the surface, and the rest of the impellers were all qualified. During the shell shaking and sand cleaning process, the mold shell in the runner was very easy to remove. It is speculated that the factor causing the unqualified products due to cracks may be that using single graphite sand as the refractory material may not be able to completely eliminate the performance differences brought by the backing material and generate invisible cracks. During pouring, the cracks are enlarged by high temperature, thus having an adverse impact on the quality of the impeller.

[0083] Comparative Example 1

[0084] A manufacturing process for an impeller mold shell includes the following steps:

[0085] 1), Inject wax paste into an impeller mold. After it cools and solidifies to form a investment mold, then assemble, bond and fix the investment mold to obtain an impeller wax mold;

[0086] 2), Clean and air-dry the impeller wax mold, then immerse the wax mold in the surface layer slurry, take it out and evenly sprinkle a layer of 100-mesh zircon sand, naturally dry it at room temperature and then blow off the floating sand. Repeat the operation of step 2) to prepare two surface layer mold shells for standby;

[0087] The surface layer slurry is composed of colloidal silica and 300-mesh zircon powder according to a weight ratio of 1:3.5.

[0088] 3), Immerse the above surface layer mold shell in the backing layer slurry, then take it out and sprinkle sand, naturally dry it at room temperature and then blow off the floating sand. Repeat the operation of step 3) to obtain two backing layer mold shells for standby;

[0089] The backing layer slurry is composed of colloidal silica and 200-mesh mullite powder according to a weight ratio of 1:1.6, and the sand for sprinkling sand is 60-mesh mullite sand.

[0090] 4), Immerse the above backing layer mold shell in the sealant layer slurry, then take it out and naturally dry it at room temperature to complete the sealing;

[0091] The sealant layer slurry is composed of colloidal silica and mullite powder, and its weight ratio is 1:1.4.

[0092] 5), Put the above mold shell after completing the sealing into a dewaxing kettle for high-pressure steam dewaxing, and take it out after dewaxing; among them, the technological parameters of dewaxing are: pressure 0.7 MPa, temperature 160 °C, and time 8 min;

[0093] 6) Place the dewaxed shell into a baking furnace for baking. After baking, cool it to room temperature with the furnace and remove it to obtain the impeller shell. The baking process parameters are: temperature 850℃, heating rate 5℃ / min, and holding time 2h.

[0094] Comparative Example 1 produced mold shells from which 50 iron alloy impellers and 50 copper alloy impellers were cast. During casting, sand was embedded in the mold under a reducing atmosphere, and the mold was then closed for cooling. However, 13 iron alloy impellers and 10 copper alloy impellers still had surface defects, resulting in product defects. Compared to the above embodiments, the product defect rate increased significantly. Furthermore, the mold shells prepared with mullite powder required sand embedding and closure under a reducing atmosphere during casting, which not only increased the operational difficulty in the smelting workshop but also, if the closure was not tight, could introduce defects, leading to an increased product defect rate.

[0095] In addition, during the shell cleaning process, the shell inside the flow channel is difficult to remove, especially the copper alloy impeller. It is speculated that the reason may be that the casting temperature of copper alloy is low, and the shell prepared by mullite powder is easy to stick to the cast model, thus making shell cleaning difficult.

Claims

1. A manufacturing process for an impeller housing, characterized in that, Includes the following steps: 1) Making wax mold: Pour wax paste into the impeller mold, wait for it to cool and solidify to form a melt pattern, and then assemble and bond the melt pattern to obtain the impeller wax mold; 2) Preparation of surface shell: Clean and dry the impeller wax mold, then immerse the wax mold in the surface slurry, take it out and evenly sprinkle a layer of 80-120 mesh zircon sand, let it dry naturally at room temperature and blow off the loose sand. Repeat step 2) to prepare a two-layer shell for later use. 3) Preparation of back shell: Immerse the above surface shell into the back slurry, then take it out and sprinkle sand. After drying naturally at room temperature, blow off the loose sand. Repeat step 3) to obtain two back shells for later use. 4) Shell sealing: Immerse the above-mentioned back shell into the sealing slurry, then take it out and let it dry naturally at room temperature to complete the sealing. 5) Dewaxing: Place the mold shell after sealing into a dewaxing kettle for high-pressure steam dewaxing, and remove it after dewaxing; 6) Firing: Place the dewaxed shell into a firing furnace for firing. After firing, cool it to room temperature with the furnace and remove it to obtain the impeller shell. In step 3), when the width of the flow channel inside the mold shell is less than 4 mm, the back layer slurry is composed of binder and graphite sand in a weight ratio of 1:(1-2), and the sand used for sprinkling is graphite sand; when the width of the flow channel inside the mold shell is greater than or equal to 4 mm, the back layer slurry is composed of binder and mullite powder in a weight ratio of 1:(1-2), and the sand used for sprinkling is mullite sand. In step 4), the sealing grout is composed of binder and refractory material in a weight ratio of 1:(1.2~2); The refractory material is a mixture of graphite sand and mullite powder in a weight ratio of (0.6-1):(0.6-1).

2. The manufacturing process of an impeller housing according to claim 1, characterized in that, In step 2), the surface slurry includes a binder and 300-325 mesh zircon powder, with a weight ratio of 1:(3-4).

3. The manufacturing process of an impeller housing according to claim 2, characterized in that, The surface slurry also includes 0.1-0.3% wetting agent and 0.1-0.3% defoamer by weight of the slurry.

4. The manufacturing process of an impeller housing according to claim 1 or 2, characterized in that, The binder is one of silica sol and water glass.

5. The manufacturing process of an impeller housing according to claim 1, characterized in that, In step 5), the dewaxing process parameters are: pressure 0.6-0.75 MPa, temperature 150-170℃, and time 6-10 min.

6. The manufacturing process of an impeller housing according to claim 1, characterized in that, In step 6), the calcination process parameters are: temperature 800-900℃, heating rate 3-8℃ / min, and holding time 1.5-3h.