Salt core, injection molded product and method for producing same, and water outlet housing

Abstract

The application discloses a salt core and a preparation method thereof, an injection molding product and a preparation method thereof, and a water outlet device shell. The water-soluble salt core comprises the following components in percentage by mass: 50-60% of sodium chloride, 5-15% of magnesium oxide, 5-10% of diatomite, 5-15% of water glass, 3-10% of polyvinyl alcohol fiber, and 3-10% of a binder. The water-soluble salt core has high mechanical strength and toughness, has good hydrolysis and collapse performance, and is helpful to the implementation of the hot water core removal process during the preparation of the metal powder injection molding product.

Description

Technical Field

[0001] This application relates to the fields of home and living technology, and in particular to a water-soluble salt core and its preparation method, a metal powder injection molded product and its preparation method, and a water outlet device housing. Background Technology

[0002] When using metal powder injection molding for faucets, the existing core-pulling mechanism can only perform straight core pulling or core pulling along curves with regular curvature. Therefore, it cannot produce irregularly shaped faucets. To achieve the production of irregularly shaped faucets using metal powder injection molding, obtaining an easily extractable core is crucial. Traditional technologies mainly include the following solutions: using resin cores made of POM (polyoxymethylene) + PVA (polyvinyl alcohol), during the injection molding process, when the mold temperature rises to 120℃, the resin core expands due to heat, blocking the powder flow channels and leading to material shortages; using aluminum alloy cores for injection molding, during the core-pulling process with sodium hydroxide, hydrogen gas is easily generated and accumulates in the faucet's inner cavity, resulting in a faucet blank that has not undergone high-temperature sintering, has low strength, and may crack. Furthermore, aluminum cores suffer from low extraction efficiency, and the use of sodium hydroxide is environmentally unfriendly. Using conventional salt cores results in insufficient salt core strength, easily leading to salt core breakage or even pulverization during the metal powder injection molding process. Summary of the Invention

[0003] Therefore, it is necessary to provide a water-soluble salt core. The water-soluble salt core of the present invention has high mechanical strength and toughness, and good hydrolytic disintegration properties, which facilitates the implementation of hot water core removal process in the preparation of metal powder injection molded products.

[0004] One embodiment of this application provides a water-soluble salt core.

[0005] A water-soluble salt core comprises the following components by mass percentage: 50%~60% sodium chloride, 5%~15% magnesium oxide, 5%~10% diatomaceous earth, 5%~15% water glass, 3%~10% polyvinyl alcohol fiber, and 3%~10% binder.

[0006] In some embodiments, the composition includes the following components by weight percentage: 50% to 60% sodium chloride, 7.5% to 12.5% ​​magnesium oxide, 5% to 8% diatomaceous earth, 5% to 12.5% ​​water glass, 3% to 7.5% polyvinyl alcohol fiber, and 5% to 10% binder.

[0007] In some embodiments, the composition includes the following components by weight percentage: 55% to 60% sodium chloride, 7.5% to 10% magnesium oxide, 7% to 7.5% diatomaceous earth, 7.5% to 12.5% ​​water glass, 5% to 7.5% polyvinyl alcohol fiber, and 5% to 7.5% binder.

[0008] In some embodiments, the binder comprises silica sol.

[0009] In some embodiments, the water-soluble salt core has a pressure resistance greater than 150 MPa, and the water-soluble salt core can be hydrolyzed and disintegrated after being soaked in hot water at a temperature of 70°C to 100°C for 30 to 120 minutes.

[0010] An embodiment of this application also provides a method for preparing a water-soluble salt core.

[0011] A method for preparing the water-soluble salt core includes the following steps:

[0012] Sodium chloride, magnesium oxide, and diatomaceous earth were dried separately.

[0013] The dried sodium chloride, magnesium oxide, diatomaceous earth, water glass, polyvinyl alcohol fiber, and binder are mixed evenly according to a preset ratio to obtain a mixed material.

[0014] The mixed material is placed in a salt core mold for pressing to obtain a pressed intermediate; and

[0015] The compressed intermediate is sintered to obtain a water-soluble salt core.

[0016] In some embodiments, the drying process is carried out at a drying temperature of 150°C to 200°C and a holding time of at least 3 hours.

[0017] In some embodiments, during the pressing process, the temperature of the salt core mold is controlled at 80℃~120℃, the pressing pressure is 200Mpa~300Mpa, and the pressing time is 3min~10min.

[0018] In some embodiments, the sintering process is carried out at a sintering temperature of 200°C to 250°C and a holding time of 0.5h to 2h.

[0019] In some embodiments, after the drying process, at least one of the following conditions is met:

[0020] (1) The particle size of the sodium chloride is controlled to be 50 μm to 100 μm;

[0021] (2) The particle size of the magnesium oxide is controlled to be 50 μm to 100 μm;

[0022] (3) The particle size of the diatomaceous earth is controlled to be 50μm~100μm.

[0023] In some embodiments, when the mixed material is placed in a salt core mold for pressing, the following step is further included: introducing pressurized CO2 into the salt core mold, wherein the pressure of the CO2 is 0.5 MPa to 1 MPa.

[0024] One embodiment of this application also provides a water-soluble salt core.

[0025] An embodiment of this application also provides a method for preparing a metal powder injection molded product.

[0026] A method for preparing a metal powder injection molded product includes the following steps:

[0027] A water-soluble salt core is placed inside the cavity of a molding die, and the gap between the water-soluble salt core and the cavity of the molding die forms a molding chamber.

[0028] Metal powder is placed in a molding cavity between the water-soluble salt core and the molding die for injection molding; and

[0029] Remove the molding die, and immerse the water-soluble salt core and the injection product in hot water at 70℃~100℃ for 30min~120min to achieve hydrolysis and disintegration of the water-soluble salt core, thereby obtaining the metal powder injection molded product.

[0030] In some embodiments, the molding pressure during injection molding is 150 MPa to 200 MPa.

[0031] In some embodiments, the metal powder includes one or more of stainless steel powder, low alloy steel powder, titanium alloy powder, and cemented carbide powder.

[0032] One embodiment of this application also provides a housing for a water outlet device.

[0033] A water outlet device housing is prepared using the aforementioned metal powder injection molding method.

[0034] The aforementioned water-soluble salt cores possess high mechanical strength and toughness, and exhibit good hydrolytic and disintegration properties, which facilitates the implementation of hot water core removal processes during the preparation of metal powder injection molded products. Detailed Implementation

[0035] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0036] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0037] In this document, unless otherwise stated, the reaction steps may be performed in the order described herein or not. For example, other steps may be included between reaction steps, and the order of reaction steps may be appropriately interchanged. This is something that those skilled in the art can determine based on conventional knowledge and experience. Preferably, the reaction methods described herein are performed sequentially.

[0038] In this application, when numerical intervals (i.e., numerical ranges) are mentioned, unless otherwise specified, the distribution of selectable numerical values ​​within the numerical interval is considered continuous, and includes the two endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that numerical interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, etc.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0040] This application provides a water-soluble salt core to address at least one of the following problems associated with conventional metal powder injection molded faucet cores: ordinary salt cores lack sufficient strength, easily leading to breakage or even pulverization; resin cores have poor thermal stability, and thermal expansion can block powder flow channels, resulting in material shortages; aluminum cores are difficult to remove, easily causing cracking of the faucet blank. The water-soluble salt core of this application can be used in applications requiring metal powder injection molded faucets.

[0041] For example, a water-soluble salt core comprises the following components by mass percentage: 50%~60% sodium chloride, 5%~15% magnesium oxide, 5%~10% diatomaceous earth, 5%~15% water glass, 3%~10% polyvinyl alcohol fiber, and 3%~10% binder.

[0042] In some embodiments, the composition includes the following components by weight percentage: 50% to 60% sodium chloride, 7.5% to 12.5% ​​magnesium oxide, 5% to 8% diatomaceous earth, 5% to 12.5% ​​water glass, 3% to 7.5% polyvinyl alcohol fiber, and 5% to 10% binder.

[0043] In some embodiments, the composition includes the following components by weight percentage: 55% to 60% sodium chloride, 7.5% to 10% magnesium oxide, 7% to 7.5% diatomaceous earth, 7.5% to 12.5% ​​water glass, 5% to 7.5% polyvinyl alcohol fiber, and 5% to 7.5% binder.

[0044] In some embodiments, the water-soluble salt core has a pressure resistance greater than 150 MPa, and the water-soluble salt core can be hydrolyzed and disintegrated after being immersed in hot water at a temperature of 70°C to 100°C for 30 to 120 minutes.

[0045] The aforementioned water-soluble salt core possesses high mechanical strength and toughness, and exhibits excellent hydrolytic disintegration properties, which facilitates the implementation of the hot water core removal process in the preparation of metal powder injection molded products. It should be noted that the aforementioned hydrolytic disintegration properties refer to the ability of the water-soluble salt core to disintegrate under water-soluble conditions at temperatures ranging from 70℃ to 100℃, demonstrating excellent water-soluble disintegration performance. Specifically, the diatomaceous earth used in this application has porous characteristics, easily connecting particles such as sodium chloride and magnesium oxide during the pressing process of water-soluble salt core preparation, thereby forming numerous three-dimensional interconnected channels and improving the strength and toughness of the water-soluble salt core. Polyvinyl alcohol fiber (PVA) has high strength and good affinity and binding properties with sodium chloride and magnesium oxide, which can improve the mechanical strength of the water-soluble salt core. Simultaneously, PVA has good water solubility, which facilitates the hot water core removal process in the preparation of metal powder injection molded products. In addition, this application has a multi-adhesive system, including an adhesive and water glass, which has strong bonding strength and together with the water glass, improves the mechanical strength of the water-soluble salt core.

[0046] In some embodiments, the binder includes silica sol. This application uses silica sol as a binder, which has strong bonding strength and, together with water glass, improves the mechanical strength of the water-soluble salt core.

[0047] An embodiment of this application also provides a method for preparing a water-soluble salt core.

[0048] A method for preparing a water-soluble salt core includes the following steps:

[0049] S1. Dry sodium chloride, magnesium oxide and diatomaceous earth separately.

[0050] S2. The dried sodium chloride, magnesium oxide, diatomaceous earth, water glass, polyvinyl alcohol fiber, and binder are mixed evenly according to a preset ratio to obtain a mixed material.

[0051] S3. Place the mixed material in a salt core mold for pressing to obtain a pressed intermediate.

[0052] S4. The pressed intermediate is sintered to obtain a water-soluble salt core.

[0053] In some embodiments, the drying process is carried out at a drying temperature of 150°C to 200°C and a holding time of at least 3 hours. The drying temperature values ​​include, but are not limited to, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, or any range between the foregoing.

[0054] In some embodiments, during the pressing process, the temperature of the salt core mold is controlled at 80℃~120℃, the pressing pressure is 200MPa~300MPa, and the pressing time is 3min~10min. The salt core mold temperature includes, but is not limited to, 80℃, 90℃, 100℃, 110℃, 120℃, or any range between the aforementioned values. The pressing pressure includes, but is not limited to, 200MPa, 210MPa, 220MPa, 230MPa, 240MPa, 250MPa, 260MPa, 270MPa, 280MPa, 290MPa, 300MPa, or any range between the aforementioned values. The pressing time includes, but is not limited to, 3min, 4min, 5min, 6min, 7min, 8min, 9min, 10min, or any range between the aforementioned values.

[0055] In some embodiments, during sintering, the sintering temperature is 200℃~250℃, and the holding time is 0.5h~2h. The sintering temperature includes, but is not limited to, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, or any range between the two. The holding time includes, but is not limited to, 0.5h, 1h, 1.5h, 2h, or any range between the two.

[0056] In some embodiments, after the drying process, at least one of the following conditions is met:

[0057] (1) Control the particle size of sodium chloride to 50μm~100μm;

[0058] (2) Control the particle size of magnesium oxide to 50μm~100μm;

[0059] (3) Control the particle size of diatomaceous earth to 50μm~100μm.

[0060] For example, in a specific instance, the particle size of sodium chloride may include, but is not limited to, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm or any range between the two aforementioned.

[0061] For example, in a specific instance, the particle size of magnesium oxide may include, but is not limited to, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm or any range between the two aforementioned.

[0062] For example, in a specific instance, the particle size of diatomaceous earth may include, but is not limited to, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm or any range between the two aforementioned.

[0063] In some embodiments, when the mixed material is placed in a salt core mold for pressing, the following step is further included: introducing pressurized CO2 into the salt core mold, wherein the pressure of the CO2 is 0.5 MPa to 1 MPa. In the preparation of water-soluble salt cores, CO2 is simultaneously introduced into the salt core mold during the pressing process. The CO2 with a certain positive pressure can rapidly harden the water glass, resulting in a water-soluble salt core with high mechanical strength and facilitating demolding of the salt core mold. The CO2 pressure value includes, but is not limited to, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1 MPa, or any range between the foregoing.

[0064] One embodiment of this application also provides a water-soluble salt core.

[0065] A water-soluble salt core is prepared by the above-mentioned method. The water-soluble salt core has a pressure resistance greater than 150 MPa and can be hydrolyzed and disintegrated after being soaked in hot water at 70℃~100℃ for 30min~120min.

[0066] An embodiment of this application also provides a method for preparing a metal powder injection molded product.

[0067] A method for preparing a metal powder injection molded product includes the following steps:

[0068] S1. Place the water-soluble salt core into the cavity of the molding mold, and the gap between the water-soluble salt core and the cavity of the molding mold forms the molding chamber.

[0069] S2. The metal powder is placed in the molding cavity between the water-soluble salt core and the molding mold cavity for injection molding.

[0070] S3. Remove the molding die, and immerse the water-soluble salt core and the injection product in hot water at a temperature of 70℃~100℃ for 30min~120min to achieve hydrolysis and disintegration of the water-soluble salt core, thereby obtaining the metal powder injection molded product.

[0071] In some embodiments, step S2, the injection molding process includes the following steps: adding metal powder to a binder and mixing them evenly to obtain a mixture; injecting the mixture into the molding chamber using an injection molding machine and pressing it at a temperature of 120°C to 150°C to obtain an injection-molded product. The mass ratio of metal powder to binder is (60~70):(30~40), and the binder includes one or more of paraffin wax, polyethylene, polystyrene, polyoxymethylene, polypropylene, stearic acid, epoxy resin, and phenolic resin.

[0072] In some embodiments, in step S3, after obtaining the metal powder injection molded product, the product is subjected to nitric acid degreasing and vacuum thermal degreasing reactions sequentially in a vacuum furnace under a nitric acid atmosphere to remove the binder. After degreasing, it is sintered at 1200℃-1500℃ for at least 30 hours to improve its structural strength. The degreasing reaction includes sequential nitric acid degreasing and vacuum thermal degreasing, with the vacuum thermal degreasing process involving a reaction at 150℃~160℃ for at least 10 hours. The degreasing reaction and sintering are carried out in the same vacuum furnace.

[0073] In some embodiments, the molding pressure during injection molding is 150 MPa to 200 MPa. The molding pressure value includes, but is not limited to: 150 MPa, 160 MPa, 170 MPa, 180 MPa, 190 MPa, 200 MPa, or any range between the foregoing.

[0074] In some embodiments, the metal powder includes one or more of stainless steel powder, low-alloy steel powder, titanium alloy powder, and cemented carbide powder. The specific type of metal powder is selected according to the product to be prepared. Cemented carbide powder is an alloy material made from a hard compound of a refractory metal and a binder metal through powder metallurgy. The hard compound of the refractory metal includes tungsten carbide (WC), titanium carbide (TiC), tantalum carbide (TaC), etc., and the binder metal includes cobalt, nickel, etc. For example, cemented carbide powder can be tungsten steel powder, etc.

[0075] One embodiment of this application also provides a housing for a water outlet device.

[0076] A water outlet device housing is prepared using the aforementioned method for preparing metal powder injection molded products.

[0077] The water outlet device housing of this application uses the aforementioned water-soluble salt core, which enables the production of irregular water outlet device housings and facilitates demolding during the production process.

[0078] In some embodiments, the water outlet housing includes irregularly shaped faucets, water pipes, and other equipment.

[0079] Example 1

[0080] This embodiment provides a water-soluble salt core.

[0081] The water-soluble salt core comprises the following components by weight percentage: 50% sodium chloride, 5% magnesium oxide, 10% diatomaceous earth, 15% water glass, 10% polyvinyl alcohol fiber, and 10% binder, wherein the binder is silica sol.

[0082] The preparation method of water-soluble salt core includes the following steps:

[0083] S1. Sodium chloride, magnesium oxide and diatomaceous earth are dried separately at a temperature of 200℃ for 3 hours.

[0084] S2. The dried sodium chloride, magnesium oxide, diatomaceous earth, water glass, polyvinyl alcohol fiber, and binder are mixed evenly according to the above-mentioned preset ratio to obtain a mixed material. Among them, sodium chloride, magnesium oxide, and diatomaceous earth with a particle size of 50μm~55μm are selected.

[0085] S3. Place the mixed material in a salt core mold, and introduce pressurized CO2 into the salt core mold. The pressure of CO2 is 0.5 MPa. Press the material to obtain a pressed intermediate. During the pressing process, the temperature of the salt core mold is controlled at 80℃, the pressing pressure is 300 MPa, and the pressing time is 3 minutes.

[0086] S4. The pressed intermediate is sintered to obtain a water-soluble salt core. The sintering temperature is 200℃ and the holding time is 2h.

[0087] The prepared water-soluble salt core was subjected to performance tests. The water-soluble salt core had a pressure resistance of 190 MPa and a tensile strength of 25 MPa. The water-soluble salt core could be hydrolyzed and disintegrated after being immersed in hot water at a temperature of 70℃~100℃ for 100 minutes.

[0088] Example 2

[0089] This embodiment provides a water-soluble salt core.

[0090] The water-soluble salt core comprises the following components by weight percentage: 60% sodium chloride, 10% magnesium oxide, 5% diatomaceous earth, 5% water glass, 10% polyvinyl alcohol fiber, and 10% binder, wherein the binder is silica sol.

[0091] The preparation method of the water-soluble salt core is the same as in Example 1.

[0092] The prepared water-soluble salt core was subjected to performance tests. The water-soluble salt core had a pressure resistance of 155 MPa and a tensile strength of 18 MPa. The water-soluble salt core could be hydrolyzed and disintegrated after being immersed in hot water at a temperature of 70℃~100℃ for 30 minutes.

[0093] Example 3

[0094] This embodiment provides a water-soluble salt core.

[0095] The water-soluble salt core comprises the following components by weight percentage: 60% sodium chloride, 15% magnesium oxide, 9% diatomaceous earth, 10% water glass, 3% polyvinyl alcohol fiber, and 3% binder, wherein the binder is silica sol.

[0096] The preparation method of the water-soluble salt core is the same as in Example 1.

[0097] The prepared water-soluble salt core was subjected to performance tests. The water-soluble salt core had a pressure resistance of 170 MPa and a tensile strength of 21 MPa. The water-soluble salt core could be hydrolyzed and disintegrated after being immersed in hot water at a temperature of 70℃~100℃ for 50 minutes.

[0098] Example 4

[0099] This embodiment provides a water-soluble salt core.

[0100] The water-soluble salt core comprises the following components by weight percentage: 55% sodium chloride, 12% magnesium oxide, 8% diatomaceous earth, 12.5% ​​water glass, 7.5% polyvinyl alcohol fiber, and 5% binder, wherein the binder is silica sol.

[0101] The preparation method of the water-soluble salt core is the same as in Example 1.

[0102] The performance of the prepared water-soluble salt core was tested. The water-soluble salt core has a pressure resistance of 175 MPa and a tensile strength of 22 MPa. The water-soluble salt core can be hydrolyzed and disintegrated after being soaked in hot water at a temperature of 70℃~100℃ for 80 minutes.

[0103] Example 5

[0104] This embodiment provides a water-soluble salt core.

[0105] The water-soluble salt core comprises the following components by mass percentage: 57.5% sodium chloride, 7.5% magnesium oxide, 7.5% diatomaceous earth, 12.5% ​​water glass, 7.5% polyvinyl alcohol fiber, and 7.5% binder, wherein the binder is silica sol.

[0106] The preparation method of the water-soluble salt core is the same as in Example 1.

[0107] The prepared water-soluble salt core was subjected to performance tests. The water-soluble salt core had a pressure resistance of 160 MPa and a tensile strength of 20 MPa. The water-soluble salt core could be hydrolyzed and disintegrated after being immersed in hot water at a temperature of 70℃~100℃ for 70 minutes.

[0108] Example 6

[0109] This embodiment provides a water-soluble salt core.

[0110] The mass percentage composition of the water-soluble salt core is the same as in Example 1.

[0111] The preparation method of the water-soluble salt core is basically the same as that in Example 1, except that in this example, step S1 uses sodium chloride with a particle size of 100 μm, magnesium oxide with a particle size of 100 μm, and diatomaceous earth with a particle size of 100 μm. The sodium chloride, magnesium oxide, and diatomaceous earth are dried separately at 150°C for 4 hours.

[0112] The prepared water-soluble salt core was tested for performance. The water-soluble salt core had a pressure resistance of 180 MPa and a tensile strength of 23 MPa. The water-soluble salt core could be hydrolyzed and disintegrated after being soaked in hot water at a temperature of 70℃~100℃ for 90 minutes.

[0113] Example 7

[0114] This embodiment provides a water-soluble salt core.

[0115] The mass percentage composition of the water-soluble salt core is the same as in Example 1.

[0116] The preparation method of water-soluble salt core is basically the same as that in Example 1, except that in this example, the pressure of CO2 in step S3 is 1 MPa.

[0117] The prepared water-soluble salt core was subjected to performance tests. The water-soluble salt core had a pressure resistance of 200 MPa and a tensile strength of 25.5 MPa. The water-soluble salt core could be hydrolyzed and disintegrated after being immersed in hot water at a temperature of 70℃~100℃ for 120 minutes.

[0118] Example 8

[0119] This embodiment provides a water-soluble salt core.

[0120] The mass percentage composition of the water-soluble salt core is the same as in Example 1.

[0121] The preparation method of water-soluble salt core is basically the same as that in Example 1, except that in this example, during the pressing process in step S3, the temperature of the salt core mold is controlled at 120°C, the pressing pressure is 200 MPa, and the pressing time is 3 min.

[0122] The prepared water-soluble salt core was subjected to performance tests. The water-soluble salt core had a pressure resistance of 178 MPa and a tensile strength of 24 MPa. The water-soluble salt core could be hydrolyzed and disintegrated after being immersed in hot water at a temperature of 70℃~100℃ for 95 minutes.

[0123] Example 9

[0124] This embodiment provides a water-soluble salt core.

[0125] The mass percentage composition of the water-soluble salt core is the same as in Example 1.

[0126] The preparation method of water-soluble salt core is basically the same as that in Example 1, except that in this example, during the pressing process in step S4, the sintering temperature is 250°C and the holding time is 0.5h.

[0127] The prepared water-soluble salt core was tested for performance. The water-soluble salt core had a pressure resistance of 185 MPa and a tensile strength of 24.5 MPa. The water-soluble salt core could be hydrolyzed and disintegrated after being soaked in hot water at a temperature of 70℃~100℃ for 100 minutes.

[0128] Comparative Example 1

[0129] This comparative example provides a water-soluble salt core.

[0130] The difference between the water-soluble salt core composition of this comparative example and that of Example 1 is that the water-soluble salt core composition of this comparative example lacks water glass. Specifically, the water-soluble salt core of this comparative example includes the following components by mass percentage: 65% sodium chloride, 5% magnesium oxide, 10% diatomaceous earth, 10% polyvinyl alcohol fiber, and 10% binder. The binder is silica sol.

[0131] The preparation method of the water-soluble salt core is the same as in Example 1.

[0132] The prepared water-soluble salt core was subjected to performance tests. The water-soluble salt core had a pressure resistance of 80 MPa and a tensile strength of 10 MPa. The water-soluble salt core could be hydrolyzed and disintegrated after being immersed in hot water at a temperature of 70℃~100℃ for 25 minutes.

[0133] Comparative Example 2

[0134] This comparative example provides a water-soluble salt core.

[0135] The difference between the water-soluble salt core composition of this comparative example and that of Example 1 is that the water-soluble salt core composition of this comparative example lacks a binder. Specifically, the water-soluble salt core of this comparative example includes the following components by mass percentage: 60% sodium chloride, 5% magnesium oxide, 10% diatomaceous earth, 15% water glass, and 10% polyvinyl alcohol fiber, wherein the binder is silica sol.

[0136] The preparation method of the water-soluble salt core is the same as in Example 1.

[0137] The prepared water-soluble salt core was subjected to performance tests. The water-soluble salt core had a pressure resistance of 95 MPa and a tensile strength of 13 MPa. The water-soluble salt core could be hydrolyzed and disintegrated after being immersed in hot water at a temperature of 70℃~100℃ for 70 minutes.

[0138] Comparative Example 3

[0139] This comparative example provides a water-soluble salt core.

[0140] The difference between the water-soluble salt core composition of this comparative example and that of Example 1 is that the water-soluble salt core composition of this comparative example lacks magnesium oxide. Specifically, the water-soluble salt core of this comparative example includes the following components by mass percentage: 55% sodium chloride, 10% diatomaceous earth, 15% water glass, 10% polyvinyl alcohol fiber, and 10% binder, wherein the binder is silica sol.

[0141] The preparation method of the water-soluble salt core is the same as in Example 1.

[0142] The prepared water-soluble salt core was subjected to performance tests. The water-soluble salt core had a pressure resistance of 115 MPa and a tensile strength of 13 MPa. The water-soluble salt core could be hydrolyzed and disintegrated after being immersed in hot water at a temperature of 70℃~100℃ for 90 minutes.

[0143] Comparative Example 4

[0144] This comparative example provides a water-soluble salt core.

[0145] The difference between the water-soluble salt core composition of this comparative example and that of Example 1 is that the water-soluble salt core composition of this comparative example lacks diatomaceous earth. Specifically, the water-soluble salt core of this comparative example includes the following components by mass percentage: 60% sodium chloride, 5% magnesium oxide, 15% water glass, 10% polyvinyl alcohol fiber, and 10% binder, wherein the binder is silica sol.

[0146] The preparation method of the water-soluble salt core is the same as in Example 1.

[0147] The prepared water-soluble salt core was subjected to performance tests. The water-soluble salt core had a pressure resistance of 100 MPa and a tensile strength of 11 MPa. The water-soluble salt core could be hydrolyzed and disintegrated after being immersed in hot water at a temperature of 70℃~100℃ for 80 minutes.

[0148] Comparative Example 5

[0149] This comparative example provides a water-soluble salt core.

[0150] The difference between the water-soluble salt core composition of this comparative example and that of Example 1 is that the water-soluble salt core composition of this comparative example lacks polyvinyl alcohol fiber. Specifically, the water-soluble salt core of this comparative example includes the following components by mass percentage: 60% sodium chloride, 5% magnesium oxide, 10% diatomaceous earth, 15% water glass, and 10% binder, wherein the binder is silica sol.

[0151] The preparation method of the water-soluble salt core is the same as in Example 1.

[0152] The prepared water-soluble salt core was subjected to performance tests. The water-soluble salt core had a pressure resistance of 115 MPa and a tensile strength of 16 MPa. The water-soluble salt core could be hydrolyzed and disintegrated after being immersed in hot water at a temperature of 70℃~100℃ for 130 minutes.

[0153] Comparative Example 6

[0154] This comparative example provides a water-soluble salt core.

[0155] The difference between the water-soluble salt core composition of this comparative example and that of Example 1 is that the water-soluble salt core of this comparative example includes the following components by mass percentage: 53% sodium chloride, 2% magnesium oxide, 10% diatomaceous earth, 15% water glass, 10% polyvinyl alcohol fiber, and 10% binder, wherein the binder is silica sol.

[0156] The preparation method of the water-soluble salt core is the same as in Example 1.

[0157] The prepared water-soluble salt core was subjected to performance tests. The water-soluble salt core had a pressure resistance of 120 MPa and a tensile strength of 14 MPa. The water-soluble salt core could be hydrolyzed and disintegrated after being immersed in hot water at a temperature of 70℃~100℃ for 93 minutes.

[0158] Comparative Example 7

[0159] This comparative example provides a water-soluble salt core.

[0160] The difference between the water-soluble salt core composition of this comparative example and that of Example 1 is that the water-soluble salt core of this comparative example includes the following components by mass percentage: 57% sodium chloride, 5% magnesium oxide, 3% diatomaceous earth, 15% water glass, 10% polyvinyl alcohol fiber, and 10% binder, wherein the binder is silica sol.

[0161] The preparation method of the water-soluble salt core is the same as in Example 1.

[0162] The prepared water-soluble salt core was subjected to performance tests. The water-soluble salt core had a pressure resistance of 110 MPa and a tensile strength of 13 MPa. The water-soluble salt core could be hydrolyzed and disintegrated after being immersed in hot water at a temperature of 70℃~100℃ for 82 minutes.

[0163] Comparative Example 8

[0164] This comparative example provides a water-soluble salt core.

[0165] The difference between the water-soluble salt core composition of this comparative example and that of Example 1 is that the water-soluble salt core of this comparative example includes the following components by mass percentage: 62% sodium chloride, 5% magnesium oxide, 10% diatomaceous earth, 3% water glass, 10% polyvinyl alcohol fiber, and 10% binder, wherein the binder is silica sol.

[0166] The preparation method of the water-soluble salt core is the same as in Example 1.

[0167] The prepared water-soluble salt core was subjected to performance tests. The water-soluble salt core had a pressure resistance of 90 MPa and a tensile strength of 12 MPa. The water-soluble salt core could be hydrolyzed and disintegrated after being immersed in hot water at a temperature of 70℃~100℃ for 38 minutes.

[0168] Comparative Example 9

[0169] This comparative example provides a water-soluble salt core.

[0170] The difference between the water-soluble salt core composition of this comparative example and that of Example 1 is that the water-soluble salt core of this comparative example includes the following components by mass percentage: 58% sodium chloride, 5% magnesium oxide, 10% diatomaceous earth, 15% water glass, 2% polyvinyl alcohol fiber, and 10% binder, wherein the binder is silica sol.

[0171] The preparation method of the water-soluble salt core is the same as in Example 1.

[0172] The prepared water-soluble salt core was subjected to performance tests. The water-soluble salt core had a pressure resistance of 120 MPa and a tensile strength of 17 MPa. The water-soluble salt core could be hydrolyzed and disintegrated after being immersed in hot water at a temperature of 70℃~100℃ for 120 minutes.

[0173] Comparative Example 10

[0174] This comparative example provides a water-soluble salt core.

[0175] The difference between the water-soluble salt core composition of this comparative example and that of Example 1 is that the water-soluble salt core of this comparative example includes the following components by mass percentage: 58% sodium chloride, 5% magnesium oxide, 10% diatomaceous earth, 15% water glass, 10% polyvinyl alcohol fiber, and 2% binder, wherein the binder is silica sol.

[0176] The preparation method of the water-soluble salt core is the same as in Example 1.

[0177] The prepared water-soluble salt core was subjected to performance tests. The water-soluble salt core had a pressure resistance of 100 MPa and a tensile strength of 14 MPa. The water-soluble salt core could be hydrolyzed and disintegrated after being soaked in hot water at a temperature of 70℃~100℃ for 60 minutes.

[0178] As can be seen from Examples 1-9 and Comparative Examples 1-10, when the content of magnesium oxide, diatomaceous earth, water glass, polyvinyl alcohol fiber, or binder in the water-soluble salt core is too low or absent, it will affect the mechanical strength and toughness of the water-soluble salt core, resulting in lower pressure resistance of the water-soluble salt core, which is not conducive to the preparation of metal powder injection molded products. Since the molding pressure during injection molding in the preparation process of metal powder injection molded products is 150Mpa~200Mpa, and diatomaceous earth has the characteristic of being porous, it is easy to connect particles such as sodium chloride and magnesium oxide during the processing and pressing process of water-soluble salt core preparation, thereby forming a large number of three-dimensional through channels, which improves the strength and toughness of water-soluble salt core. Reducing the diatomaceous earth content to below 5% or excluding diatomaceous earth will prevent the formation of effective three-dimensional through channels, thereby reducing the strength of the salt core. The composite bonding system of water glass and silica sol can significantly improve the strength and pressure resistance of the salt core. Reducing the water glass content to below 5% or the silica sol content to below 3%, while accelerating the dissolution efficiency of the salt core, also significantly reduces strength and pressure resistance. Polyvinyl alcohol fiber (PVA) has high strength and good affinity and binding properties with sodium chloride and magnesium oxide, which can improve the mechanical strength of the water-soluble salt core. Simultaneously, PVA's good water solubility facilitates hot water core removal during the metal powder injection molding process. When the PVA fiber content is below 3%, the mechanical strength of the salt core also decreases significantly. Magnesium oxide has high hardness, and its dispersed distribution in the salt core can improve its impact resistance; however, when the magnesium oxide content is below 5%, the strengthening effect is poor. Therefore, the water-soluble salt cores in Comparative Examples 1 to 10 cannot withstand the molding pressure, resulting in poor injection molding performance or injection molding failure in the metal powder injection molding process, making it impossible to produce metal powder injection molded products.

[0179] In summary, the water-soluble salt core of this application has high mechanical strength and toughness, and good hydrolysis and disintegration properties, which is helpful for the implementation of hot water core removal process in the preparation of metal powder injection molded products.

[0180] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0181] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0182] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A water soluble salt core, characterized in that, The water-soluble salt core comprises the following components in percentage by mass: sodium chloride 50-60%, magnesium oxide 5-15%, diatomite 5-10%, water glass 5-15%, polyvinyl alcohol fiber 3-10%, and binder 3-10%, wherein the binder comprises silica sol, and the water-soluble salt core has a pressure resistance greater than 150 MPa.

2. The water soluble salt core according to claim 1, wherein, The water-soluble salt core comprises the following components in percentage by mass: sodium chloride 50-60%, magnesium oxide 7.5-12.5%, diatomite 5-8%, water glass 5-12.5%, polyvinyl alcohol fiber 3-7.5%, and binder 5-10%, wherein the binder comprises silica sol, and the water-soluble salt core has a pressure resistance greater than 150 MPa.

3. The water soluble salt core of claim 1, wherein, The water-soluble salt core comprises the following components in percentage by mass: sodium chloride 55-60%, magnesium oxide 7.5-10%, diatomite 7-7.5%, water glass 7.5-12.5%, polyvinyl alcohol fiber 5-7.5%, and binder 5-7.5%, wherein the binder comprises silica sol, and the water-soluble salt core has a pressure resistance greater than 150 MPa.

4. The water-soluble salt core according to any one of claims 1 to 3, characterized in that The water-soluble salt core can be hydrolyzed and disintegrated after being soaked in hot water at a temperature of 70-100°C for 30-120 min.

5. A process for producing the water-soluble salt core according to any one of claims 1 to 4, characterized by, The method comprises the following steps: The sodium chloride, magnesium oxide, and diatomite are dried respectively; The dried sodium chloride, magnesium oxide, and diatomite are mixed with the water glass, polyvinyl alcohol fiber, and binder according to a preset ratio to obtain a mixed material; The mixed material is placed in a salt core mold for compression treatment to obtain a compression intermediate; and The compression intermediate is sintered to obtain the water-soluble salt core.

6. The method of claim 5, wherein the water-soluble salt core is prepared by the steps of: During the drying treatment, the drying temperature is 150-200°C, and the holding time is at least 3 h.

7. The method of claim 5, wherein the water-soluble salt core is prepared by the steps of: During the compression treatment, the temperature of the salt core mold is controlled to be 80-120°C, the compression pressure is 200-300 MPa, and the compression time is 3-10 min.

8. The method of producing a water soluble salt core according to any one of claims 5 to 7, characterized by, During the sintering treatment, the sintering temperature is 200-250°C, and the holding time is 0.5-2 h.

9. The method of producing a water-soluble salt core according to any one of claims 5 to 7, characterized by, After the drying treatment, at least one of the following conditions is satisfied: (1) the particle size of the sodium chloride is controlled to be 50-100 μm; (2) the particle size of the magnesium oxide is controlled to be 50-100 μm; (3) the particle size of the diatomite is controlled to be 50-100 μm.

10. The method of producing a water-soluble salt core according to any one of claims 5 to 7, characterized by, When the mixed material is placed in the salt core mold for compression treatment, the following step is further included: CO2 at a pressure of 0.5-1 MPa is introduced into the salt core mold.

11. A method for the production of a metal powder injection molded product, characterized in that, The method comprises the following steps: The water-soluble salt core of any one of claims 1-4 or prepared by the method of any one of claims 5-10 is placed in a cavity of a forming mold, and a gap between the water-soluble salt core and the cavity of the forming mold forms a forming chamber; Metal powder is placed in the forming chamber between the water-soluble salt core and the cavity of the forming mold for injection molding; and ​ The forming mold is removed, the water-soluble salt core is soaked in hot water at a temperature of 70-100 ℃ for 30-120 min with the injection product, the water-soluble salt core is hydrolyzed and scattered, and a metal powder injection molding product is obtained.

12. The method of producing a metal powder injection molded product according to claim 11, characterized in that, During injection molding, the molding pressure is 150-200 MPa.

13. The method of producing a metal powder injection molded product according to claim 11, characterized by, The metal powder comprises one or more of stainless steel powder, low-alloy steel powder, titanium alloy powder and hard alloy powder.

14. A water outlet device housing, characterized by The metal powder injection molding product is prepared by the method of any one of claims 11-13.