Ceramic salt core for high pressure casting of coolant runner plate

Abstract

The application relates to the technical field of casting, and discloses a ceramic salt core for high-pressure casting of a refrigerant runner plate, which comprises the following components in parts by weight: sodium chloride, aluminum borate whisker, nano zirconium oxide, sodium carboxymethyl cellulose, silicon carbide nano particles, octadecane and sodium dodecyl sulfate; a silane film with a thickness of 5-10 nm is formed on the surface of the sodium chloride particles; the ceramic salt core for high-pressure casting of the refrigerant runner plate and the preparation process thereof are characterized in that, in the raw material aspect, the components such as sodium chloride, aluminum borate whisker and nano zirconium oxide are accurately proportioned, the sodium chloride is subjected to surface modification, and the aluminum borate whisker is subjected to ultrasonic dispersion treatment, so that the synergistic effect among the components is effectively enhanced. The modified sodium chloride is combined with other materials more closely, the aluminum borate whisker after dispersion treatment is uniformly distributed, the compressive strength of the ceramic salt core is greatly improved, the ceramic salt core is not prone to breakage in the high-pressure casting environment, and the casting success rate is improved.

Description

Technical Field

[0001] This invention relates to the field of casting technology, specifically to a ceramic salt core for high-pressure casting of a refrigerant flow channel plate. Background Technology

[0002] In modern industry, especially in sectors such as new energy vehicles and refrigeration equipment, refrigerant flow channels are key components, and the precision and quality of their manufacturing process directly affect the operating efficiency and reliability of the equipment.

[0003] High-pressure casting technology, with its high efficiency and precision, has become one of the mainstream processes for manufacturing refrigerant flow channel plates. Ceramic salt cores, acting as soluble cores in high-pressure casting, play a crucial role in forming the flow channel cavities. The ceramic salt core must possess good strength to withstand the casting pressure, while also requiring high dimensional accuracy and excellent thermal stability to ensure that the shape and dimensions of the flow channel meet design requirements after casting, and to remain stable at high temperatures, preventing deformation or cracking.

[0004] However, existing ceramic salt cores for high-pressure casting of refrigerant flow channels have many problems in practical applications. Some ceramic salt cores have insufficient compressive strength due to unreasonable raw material ratios, making them prone to breakage and damage during high-pressure casting, affecting the casting yield. Some products have poor thermal stability and are prone to softening and deformation under the action of high-temperature molten metal, resulting in deviations in flow channel dimensions.

[0005] To address the aforementioned issues, this invention provides a ceramic salt core for high-pressure casting of refrigerant flow channel plates and its preparation process. By optimizing the raw material ratio and innovating the preparation process, the comprehensive performance of the ceramic salt core is significantly improved, meeting the demands of modern industry for high-precision, high-performance casting cores. Summary of the Invention

[0006] To address the problems in the prior art, this invention provides a ceramic salt core for high-pressure casting of refrigerant flow channel plates.

[0007] The technical solution adopted by this invention to solve its technical problem is: a ceramic salt core for high-pressure casting of a refrigerant flow channel plate, comprising the following components in parts by weight: 67-69 parts sodium chloride, 7-9 parts aluminum borate whiskers, 4-4.5 parts nano-zirconia, 2-2.3 parts sodium carboxymethyl cellulose, 0.7-0.9 parts silicon carbide nanoparticles, 0.3-0.5 parts octadecane, and 0.1-0.2 parts sodium dodecyl sulfate;

[0008] A silane film with a thickness of 5-10 nm is formed on the surface of the sodium chloride particles, and the flexural strength of the ceramic salt core is ≥200 MPa, with significantly improved thermal shock resistance.

[0009] As a further technical solution, the silane membrane is generated by silane coupling agent KH-560, and the amount of silane coupling agent KH-560 is 0.5-0.8% of the mass of sodium chloride.

[0010] As a further technical solution, the specific method for forming a silane film on the surface of the sodium chloride particles is as follows: prepare an anhydrous ethanol solution with a mass fraction of 1.2-1.5% using silane coupling agent KH-560; add the sodium chloride particles to the above solution and stir the reaction at 50-60℃ for 2-2.5 hours; after the reaction is completed, filter the solution, wash the sodium chloride particles with anhydrous ethanol 2-3 times, and then vacuum dry them at 70-80℃ for 3-5 hours, maintaining the vacuum degree at -0.06 to -0.07 MPa.

[0011] As a further technical solution, the aluminum borate whiskers have an aspect ratio of 35-45, and are dispersed in anhydrous ethanol at an ultrasonic frequency of 45-50 kHz for 35-40 minutes before being mixed with other components.

[0012] As a further technical solution, the average particle size of the nano-zirconia is 60-70 nm. As a further technical solution, the average particle size of the silicon carbide nanoparticles is 30-50 nm, which is used to enhance the thermal conductivity and wear resistance of the salt core.

[0013] As a further technical solution, the phase transition temperature of the octadecane is 28-30℃, which is used to regulate the temperature during the salt core casting process and reduce thermal stress.

[0014] Sodium dodecyl sulfate is used to reduce the surface energy of the particle surfaces of each component and improve the mixing and dispersibility of raw materials.

[0015] The method for preparing the ceramic salt core for high-pressure casting of the refrigerant flow channel plate includes:

[0016] Surface-modified sodium chloride, ultrasonically dispersed aluminum borate whiskers, nano-zirconia, sodium carboxymethyl cellulose, silicon carbide nanoparticles, octadecane, and sodium dodecyl sulfate were weighed in proportion and ball-milled with anhydrous ethanol for 3-3.5 hours. The ball-milled material was vacuum-dried to constant weight at a vacuum of -0.08 to -0.09 MPa and 60-70°C. It was then formed using a cold isostatic press at a pressure of 220-245 MPa and held for 15-20 minutes. The material was first pre-sintered at 620°C with a heating rate of 12°C / min and held for 30 minutes, then heated to 860°C with a heating rate of 6°C / min and held for 2.5 hours. Finally, it was cooled to room temperature at a rate of 8°C / min under an argon protective atmosphere.

[0017] As a further technical solution, during the ball milling process, the ball milling speed is 350-400 r / min, the grinding balls are made of zirconium oxide, and the ball-to-material ratio is 10:1.

[0018] The beneficial effects of this invention are:

[0019] The present invention relates to a ceramic salt core for high-pressure casting of refrigerant flow channel plates and its preparation process. In terms of raw materials, by precisely proportioning sodium chloride, aluminum borate whiskers, and nano-zirconia, and by surface-modifying the sodium chloride and ultrasonically dispersing the aluminum borate whiskers, the synergistic effect between the components is effectively enhanced. The modified sodium chloride bonds more tightly with other materials, and the dispersed aluminum borate whiskers are evenly distributed, significantly improving the compressive strength of the ceramic salt core, making it less prone to breakage under high-pressure casting conditions, and increasing the casting success rate.

[0020] This invention optimizes the proportions of each component in the formulation and adds various functional substances, such as silicon carbide nanoparticles, octadecane, and sodium dodecyl sulfate. The silicon carbide nanoparticles, in synergy with aluminum borate whiskers and nano-zirconia, significantly improve the thermal conductivity, wear resistance, and flexural strength of the salt core, enabling it to withstand high temperatures and pressures during high-pressure casting without easily deforming or cracking, thus ensuring the forming accuracy of the refrigerant runner plate. Octadecane, as a phase change material, can regulate the temperature during the casting process, reduce thermal stress, greatly improve the thermal shock resistance of the salt core, reduce crack formation, and ensure the internal quality of the runner plate.

[0021] In terms of manufacturing process, the raw material processing and sintering processes are precisely controlled. For example, surface modification of sodium chloride particles enhances the interfacial bonding with other components; specific rotation speed, ball-to-material ratio, and grinding ball material during ball milling ensure uniform dispersion of the raw materials; and reasonable adjustment of the heating rate during sintering avoids internal defects caused by excessively rapid temperature changes. These improvements allow the cast refrigerant flow channel plate to directly meet usage requirements without secondary welding, reducing production steps and costs, improving production efficiency and product quality, while eliminating welding defects, enhancing the sealing performance and overall strength of the flow channel plate, and providing a reliable guarantee for the efficient and stable operation of refrigeration equipment.

[0022] Sodium chloride was selected as the matrix material due to its high melting point, providing a fundamental high-temperature resistance for the ceramic salt core. Surface modification treatment was applied to form a dense nanoscale silane film on the surface of the sodium chloride particles. This film enhances the interfacial bonding between sodium chloride and other components, reducing defects caused by interfacial differences during molding and sintering. Furthermore, the presence of the silane film effectively inhibits grain growth of sodium chloride at high temperatures, ensuring a stable microstructure for the salt core in the high-temperature casting environment, thereby improving overall mechanical properties. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The ceramic salt core for high-pressure casting of refrigerant flow channel plates of the present invention is prepared with high-performance ceramic salt core through specific raw material ratios and preparation processes.

[0025] Raw material preparation

[0026] The raw materials used in this method, including sodium chloride, aluminum borate whiskers, nano-zirconia, sodium carboxymethyl cellulose, silicon carbide nanoparticles, octadecane, sodium dodecyl sulfate, silane coupling agent KH-560, and anhydrous ethanol, are all commercially available chemically pure or analytically pure reagents.

[0027] Raw material pretreatment

[0028] Sodium chloride surface modification: Prepare an anhydrous ethanol solution with a mass fraction of 1.2-1.5% using silane coupling agent KH-560; add sodium chloride particles to the above solution and stir at 50-60℃ for 2-2.5 hours; after the reaction, filter, wash the sodium chloride particles with anhydrous ethanol 2-3 times, and then vacuum dry at 70-80℃ for 3-5 hours, maintaining the vacuum degree at -0.06 to -0.07 MPa, so that a silane film with a thickness of 5-10 nm is formed on the surface of the sodium chloride particles. The amount of silane coupling agent KH-560 used is 0.5-0.8% of the mass of sodium chloride.

[0029] Ultrasonic dispersion of aluminum borate whiskers: Place aluminum borate whiskers with an aspect ratio of 35-45 in anhydrous ethanol and disperse them at an ultrasonic frequency of 45-50 kHz for 35-40 min.

[0030] Ceramic salt core preparation steps

[0031] Ingredients and ball milling: Surface-modified sodium chloride, ultrasonically dispersed aluminum borate whiskers, nano-zirconia with an average particle size of 60-70 nm, sodium carboxymethyl cellulose, silicon carbide nanoparticles with an average particle size of 30-50 nm, octadecane and sodium dodecyl sulfate with a phase transformation temperature of 28-30℃ are weighed in proportion, and ball milled for 3-3.5 hours with anhydrous ethanol as the medium at a ball milling speed of 350-400 r / min. The grinding balls are made of zirconia material, and the ball-to-material ratio is 10:1.

[0032] Vacuum drying: The ball-milled material is vacuum dried to constant weight under vacuum conditions of -0.08 to -0.09 MPa and 60-70℃.

[0033] Cold isostatic pressing: The cold isostatic press is used to form the material under a pressure of 220-245MPa and hold the pressure for 15-20 minutes.

[0034] Sintering and cooling: First, the temperature is raised to 620℃ at 12℃ / min and held for 30min for pre-sintering. Then, the temperature is raised to 860℃ at 6℃ / min and held for 2.5 hours. Finally, the temperature is cooled to room temperature at a rate of 8℃ / min under an argon protective atmosphere.

[0035] Aluminum borate whiskers possess high strength, high modulus, and good high-temperature resistance, acting as a skeletal support in the salt core and significantly improving its flexural strength. Before use, placing the aluminum borate whiskers in anhydrous ethanol and ultrasonically dispersing them effectively breaks up whisker agglomeration, ensuring uniform dispersion during raw material mixing and maximizing their reinforcing effect.

[0036] Zirconia undergoes a phase transformation at high temperatures, resulting in enhanced toughness. When the salt core is subjected to external forces or thermal stress, the zirconia particles transform from the tetragonal phase to the monoclinic phase, absorbing energy and thus improving the thermal shock resistance and toughness of the salt core. Simultaneously, nanoscale zirconia particles can fill the gaps between the matrix and whiskers, refining the grain size and improving the microstructure of the salt core.

[0037] Silicon carbide possesses high hardness, high thermal conductivity, and good chemical stability, enabling it to synergistically interact with aluminum borate whiskers and nano-zirconia. On one hand, silicon carbide nanoparticles can enhance the thermal conductivity of the salt core, accelerate heat transfer during the casting process, and reduce thermal stress. On the other hand, its high hardness can improve the wear resistance of the salt core, reduce wear caused by friction with the mold during casting, and extend the service life of the salt core.

[0038] Sodium carboxymethyl cellulose (CMC) is used as a binder. CMC possesses excellent water solubility and adhesive properties, enabling it to tightly bind the component particles together during powder compression molding, forming a green body structure with a certain strength. Simultaneously, CMC decomposes and volatilizes during high-temperature sintering, leaving no residue inside the salt core that could affect its performance. Furthermore, the decomposition process is relatively mild, preventing the generation of large amounts of gas that could lead to defects such as porosity in the salt core. Moreover, by adjusting the amount of CMC added, the porosity and density of the salt core can be controlled to a certain extent, meeting the performance requirements of different casting processes.

[0039] Octadecylane has a phase transition temperature of approximately 28-30℃. During the salt core casting process, when the temperature rises to the phase transition temperature, octadecylane changes from a solid to a liquid state, absorbing a large amount of heat and regulating the salt core temperature. This temperature regulation function effectively reduces the thermal stress of the salt core during the heating process, improves the thermal shock resistance of the salt core, and helps stabilize the temperature field during the casting process, resulting in more uniform and precise molding of the refrigerant flow channel plate.

[0040] During the raw material mixing process, sodium dodecyl sulfate can reduce the surface energy of the particle surfaces of each component, improve the dispersibility between particles, and make the particles such as sodium chloride, aluminum borate whiskers, and nano-zirconia more uniformly mixed during ball milling, avoiding local agglomeration and further improving the performance consistency of the salt core.

[0041] The following are specific embodiments. Example

[0042] Raw material ratio: 67 parts sodium chloride, 7 parts aluminum borate whiskers, 4 parts nano zirconium oxide, 2 parts sodium carboxymethyl cellulose, 0.7 parts silicon carbide nanoparticles, 0.3 parts octadecane, and 0.1 parts sodium dodecyl sulfate.

[0043] Preparation process

[0044] Ingredients and ball milling: Sodium chloride with surface modification and silane coupling agent KH-560 at 0.5% of sodium chloride mass, aluminum borate whiskers dispersed at 45kHz ultrasonic frequency for 35min, nano-zirconia with an average particle size of 60nm, sodium carboxymethyl cellulose, silicon carbide nanoparticles with an average particle size of 30nm, octadecane and sodium dodecyl sulfate with a phase transformation temperature of 28-30℃ are weighed in proportion, ball milled for 3 hours with anhydrous ethanol as the medium, ball milling speed of 350r / min, grinding balls made of zirconia material, and ball-to-material ratio of 10:1.

[0045] Vacuum drying: The ball-milled material is vacuum dried to constant weight under vacuum conditions of -0.08MPa and 60℃.

[0046] Cold isostatic pressing: The cold isostatic press is used to form the material under a pressure of 220MPa and hold the pressure for 15 minutes.

[0047] Sintering and cooling: First, the temperature was raised to 620℃ at 12℃ / min and held for 30 min for pre-sintering. Then, the temperature was raised to 860℃ at 6℃ / min and held for 2.5 hours. Subsequently, the temperature was cooled to room temperature at a rate of 8℃ / min under an argon protective atmosphere. The final ceramic salt core showed good performance after testing. Example

[0048] Raw material ratio: 68 parts sodium chloride, 8 parts aluminum borate whiskers, 4.2 parts nano zirconium oxide, 2.1 parts sodium carboxymethyl cellulose, 0.8 parts silicon carbide nanoparticles, 0.4 parts octadecane, and 0.15 parts sodium dodecyl sulfate.

[0049] Preparation process

[0050] Ingredients and ball milling: Sodium chloride with surface modification and silane coupling agent KH-560 at a concentration of 0.6% of sodium chloride mass, aluminum borate whiskers dispersed at 47kHz ultrasonic frequency for 37min, nano-zirconia with an average particle size of 60nm, sodium carboxymethyl cellulose, silicon carbide nanoparticles with an average particle size of 30nm, octadecane and sodium dodecyl sulfate with a phase transition temperature of 28-30℃, were weighed in proportion and ball-milled for 3.2 hours with anhydrous ethanol as the medium at a ball milling speed of 360r / min. The grinding balls were made of zirconia material, and the ball-to-material ratio was 10:1.

[0051] Vacuum drying: The ball-milled material is vacuum dried to constant weight under vacuum conditions of -0.085MPa and 65℃.

[0052] Cold isostatic pressing: The cold isostatic press is used to form the material under a pressure of 230MPa and hold the pressure for 17 minutes.

[0053] Sintering and cooling: First, the temperature was raised to 620℃ at 12℃ / min and held for 30 min for pre-sintering. Then, the temperature was raised to 860℃ at 6℃ / min and held for 2.5 hours. Subsequently, the temperature was cooled to room temperature at a rate of 8℃ / min under an argon protective atmosphere. The final ceramic salt core exhibited better performance than that of Example 1. Example

[0054] Raw material ratio: 69 parts sodium chloride, 9 parts aluminum borate whiskers, 4.5 parts nano zirconium oxide, 2.3 parts sodium carboxymethyl cellulose, 0.9 parts silicon carbide nanoparticles, 0.5 parts octadecane, and 0.2 parts sodium dodecyl sulfate.

[0055] Preparation process

[0056] Ingredients and ball milling: Sodium chloride with surface modification and silane coupling agent KH-560 at 0.8% of sodium chloride mass, aluminum borate whiskers dispersed at 50kHz ultrasonic frequency for 40min, nano-zirconia with an average particle size of 60nm, sodium carboxymethyl cellulose, silicon carbide nanoparticles with an average particle size of 30nm, octadecane and sodium dodecyl sulfate with a phase transition temperature of 28-30℃, were weighed in proportion and ball milled for 3.5 hours with anhydrous ethanol as the medium at a ball milling speed of 400r / min. The grinding balls were made of zirconia material and the ball-to-material ratio was 10:1.

[0057] Vacuum drying: The ball-milled material is vacuum dried to constant weight under vacuum conditions of -0.09MPa and 70℃.

[0058] Cold isostatic pressing: The cold isostatic press is used to form the material under a pressure of 245MPa and hold the pressure for 20 minutes.

[0059] Sintering and cooling: First, pre-sinter by heating to 620℃ at 12℃ / min and holding for 30min, then heating to 860℃ at 6℃ / min and holding for 2.5 hours, followed by cooling to room temperature at a rate of 8℃ / min under an argon protective atmosphere. The resulting ceramic salt core exhibited the best performance. Example

[0060] Raw material ratio: 67.5 parts sodium chloride, 7.5 parts aluminum borate whiskers, 4.1 parts nano zirconium oxide, 2.05 parts sodium carboxymethyl cellulose, 0.75 parts silicon carbide nanoparticles, 0.35 parts octadecane, and 0.12 parts sodium dodecyl sulfate.

[0061] Preparation process

[0062] Ingredients and ball milling: Sodium chloride with surface modification and silane coupling agent KH-560 at a mass of 0.65% of sodium chloride, aluminum borate whiskers dispersed at 46kHz ultrasonic frequency for 36min, nano-zirconia with an average particle size of 70nm, sodium carboxymethyl cellulose, silicon carbide nanoparticles with an average particle size of 50nm, octadecane and sodium dodecyl sulfate with a phase transition temperature of 28-30℃ were weighed in proportion, ball milled for 3.1 hours with anhydrous ethanol as the medium, ball milling speed of 370r / min, grinding balls made of zirconia material, and ball-to-material ratio of 10:1.

[0063] Vacuum drying: The ball-milled material is vacuum dried to constant weight under vacuum conditions of -0.083 MPa and 63℃.

[0064] Cold isostatic pressing: The cold isostatic press is used to form the material under a pressure of 225 MPa and hold the pressure for 16 minutes.

[0065] Sintering and cooling: The temperature was first increased to 620℃ at 12℃ / min and held for 30 min for pre-sintering. Then, the temperature was increased to 860℃ at 6℃ / min and held for 2.5 hours. Subsequently, the temperature was cooled to room temperature at a rate of 8℃ / min under an argon protective atmosphere. The resulting ceramic salt core exhibited good performance, falling between that of Example 1 and Example 2.

[0066] Comparative Example

[0067] Comparative Example 1

[0068] Comparison with Example 2: The difference from Example 2 is that the sodium chloride was not subjected to surface modification treatment, but the other operations are the same.

[0069] Preparation process

[0070] Ingredients and ball milling: 68 parts of unmodified sodium chloride, aluminum borate whiskers dispersed at 47kHz ultrasonic frequency for 37min, nano-zirconia with an average particle size of 60-70nm, sodium carboxymethyl cellulose, silicon carbide nanoparticles with an average particle size of 30-50nm, octadecane and sodium dodecyl sulfate with a phase transition temperature of 28-30℃ were weighed in proportion, and ball milled for 3.2 hours with anhydrous ethanol as the medium at a ball milling speed of 360r / min. The grinding balls were made of zirconia material and the ball-to-material ratio was 10:1.

[0071] Vacuum drying: The ball-milled material is vacuum dried to constant weight under vacuum conditions of -0.085MPa and 65℃.

[0072] Cold isostatic pressing: The cold isostatic press is used to form the material under a pressure of 230MPa and hold the pressure for 17 minutes.

[0073] Sintering and cooling: First, the temperature is raised to 620℃ at 12℃ / min and held for 30min for pre-sintering. Then, the temperature is raised to 860℃ at 6℃ / min and held for 2.5 hours. Finally, the temperature is cooled to room temperature at a rate of 8℃ / min under an argon protective atmosphere.

[0074] Comparative Example 2

[0075] Comparison with Example 2: The difference from Example 2 is that the aluminum borate whiskers were not subjected to ultrasonic dispersion treatment, but the rest of the operations were the same.

[0076] Preparation process

[0077] Ingredients and ball milling: 68 parts of sodium chloride with surface modification and silane coupling agent KH-560 at 0.6% of sodium chloride mass, 8 parts of aluminum borate whiskers with an aspect ratio of 35-45 that have not undergone ultrasonic dispersion, and nano-zirconia, sodium carboxymethyl cellulose with an average particle size of 60-70 nm, silicon carbide nanoparticles with an average particle size of 30-50 nm, octadecane and sodium dodecyl sulfate with a phase transition temperature of 28-30℃ are weighed in proportion. The mixture is ball-milled for 3.2 hours with anhydrous ethanol as the medium at a ball milling speed of 360 r / min. Zirconia grinding balls are used, and the ball-to-material ratio is 10:1.

[0078] Vacuum drying: The ball-milled material is vacuum dried to constant weight under vacuum conditions of -0.085MPa and 65℃.

[0079] Cold isostatic pressing: The cold isostatic press is used to form the material under a pressure of 230MPa and hold the pressure for 17 minutes.

[0080] Sintering and cooling: First, the temperature is raised to 620℃ at 12℃ / min and held for 30min for pre-sintering. Then, the temperature is raised to 860℃ at 6℃ / min and held for 2.5 hours. Finally, the temperature is cooled to room temperature at a rate of 8℃ / min under an argon protective atmosphere.

[0081] Comparative Example 3

[0082] Comparison with Example 2: The difference from Example 2 is that the ball milling speed is 300 r / min during the ball milling process, while the rest of the operation is the same.

[0083] Preparation process

[0084] Ingredients and ball milling: Sodium chloride with surface modification and silane coupling agent KH-560 at 0.6% of sodium chloride mass, aluminum borate whiskers dispersed at 47kHz ultrasonic frequency for 37min, nano-zirconia with an average particle size of 60-70nm, sodium carboxymethyl cellulose, silicon carbide nanoparticles with an average particle size of 30-50nm, octadecane and sodium dodecyl sulfate with a phase transition temperature of 28-30℃, were weighed in proportion and ball-milled for 3.2 hours with anhydrous ethanol as the medium at a ball milling speed of 300r / min. The grinding balls were made of zirconia material, and the ball-to-material ratio was 10:1.

[0085] Vacuum drying: The ball-milled material is vacuum dried to constant weight under vacuum conditions of -0.085MPa and 65℃.

[0086] Cold isostatic pressing: The cold isostatic press is used to form the material under a pressure of 230MPa and hold the pressure for 17 minutes.

[0087] Sintering and cooling: First, the temperature is raised to 620℃ at 12℃ / min and held for 30min for pre-sintering. Then, the temperature is raised to 860℃ at 6℃ / min and held for 2.5 hours. Finally, the temperature is cooled to room temperature at a rate of 8℃ / min under an argon protective atmosphere.

[0088] test

[0089] Experiment 1: Ceramic Salt Core Compressive Strength Test

[0090] Test Method: The compressive strength was tested according to GB / T25995-2010 "Compression Test Method for Fine Ceramics". Ceramic salt cores were processed into standard specimens with dimensions of φ10mm × 20mm. Five specimens were taken from each group. A universal testing machine was used to conduct compression tests at a loading rate of 2mm / min. The maximum load at specimen failure was recorded, and the compressive strength of each group was compared.

[0091] Table 1

[0092] sample Average compressive strength (MPa) Example 1 129 Example 2 134 Example 3 140 Example 4 137 Comparative Example 1 98 Comparative Example 2 112 Comparative Example 3 125

[0093] As can be seen from Table 1, the compressive strength of the ceramic salt core prepared in the embodiments of the present invention is significantly higher than that of the comparative example, indicating that the raw material ratio and preparation process of the present invention can effectively improve the mechanical properties of the ceramic salt core.

[0094] Experiment 2: Thermal Stability Test of Ceramic Salt Core

[0095] Test Method: Following GB / T30743-2014 "Test Method for Thermal Stability of Fine Ceramics", the thermal shock test method was adopted. The ceramic salt-core sample was placed in a high-temperature furnace, heated to 800℃ and held for 30 minutes. Then, it was quickly removed and placed in room temperature water. This process was repeated, and the number of thermal shocks at which cracks or breakage occurred was recorded. A higher number of thermal shocks indicates better thermal stability.

[0096] Table 2

[0097] sample Number of thermal shocks (times) Example 1 18 Example 2 22 Example 3 25 Example 4 20 Comparative Example 1 10 Comparative Example 2 15 Comparative Example 3 16

[0098] As can be seen from Table 2, the ceramic salt core of the present invention has significantly more thermal shock cycles than the comparative example, proving that the ceramic salt core prepared by the present invention has better thermal stability and can better withstand temperature changes in practical applications.

[0099] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A ceramic salt core for high-pressure casting of a refrigerant flow channel plate, characterized in that, It comprises the following components in parts by weight: 67-69 parts sodium chloride, 7-9 parts aluminum borate whiskers, 4-4.5 parts nano-zirconia, 2-2.3 parts sodium carboxymethyl cellulose, 0.7-0.9 parts silicon carbide nanoparticles, 0.3-0.5 parts octadecane, and 0.1-0.2 parts sodium dodecyl sulfate; A silane film with a thickness of 5-10 nm is formed on the surface of the sodium chloride particles; The specific method for forming a silane film on the surface of the sodium chloride particles is as follows: Silane coupling agent KH-560 is prepared into an anhydrous ethanol solution with a mass fraction of 1.2-1.5%; sodium chloride particles are added to the above solution and stirred at 50-60°C for 2-2.5 hours; after the reaction is completed, the mixture is filtered, and the sodium chloride particles are washed with anhydrous ethanol 2-3 times, and then vacuum dried at 70-80°C for 3-5 hours, with the vacuum degree maintained at -0.06 to -0.07 MPa; The aluminum borate whiskers have an aspect ratio of 35-45 and are dispersed in anhydrous ethanol at an ultrasonic frequency of 45-50 kHz for 35-40 minutes before being mixed with other components.

2. The ceramic salt core for high-pressure casting of the refrigerant flow channel plate according to claim 1, characterized in that, The silane membrane is generated by silane coupling agent KH-560, and the amount of silane coupling agent KH-560 used is 0.5-0.8% of the mass of sodium chloride.

3. The ceramic salt core for high-pressure casting of refrigerant flow channel plate according to claim 1, characterized in that, The average particle size of the nano-zirconia is 60-70 nm.

4. The ceramic salt core for high-pressure casting of refrigerant flow channel plate according to claim 1, characterized in that, The average particle size of the silicon carbide nanoparticles is 30-50 nm.

5. The ceramic salt core for high-pressure casting of the refrigerant flow channel plate according to claim 1, characterized in that, The phase transition temperature of the octadecane is 28-30°C.

6. The ceramic salt core for high-pressure casting of refrigerant flow channel plate according to any one of claims 1-5, characterized in that, Preparation methods include: Surface-modified sodium chloride, ultrasonically dispersed aluminum borate whiskers, nano-zirconia, sodium carboxymethyl cellulose, silicon carbide nanoparticles, octadecane, and sodium dodecyl sulfate were weighed in proportion and ball-milled with anhydrous ethanol for 3-3.5 hours. The ball-milled material was vacuum-dried to constant weight at a vacuum of -0.08 to -0.09 MPa and 60-70°C. It was then formed using a cold isostatic press at a pressure of 220-245 MPa and held for 15-20 minutes. The material was first pre-sintered at 620°C with a heating rate of 12°C / min and held for 30 minutes, then heated to 860°C with a heating rate of 6°C / min and held for 2.5 hours. Finally, it was cooled to room temperature at a rate of 8°C / min under an argon protective atmosphere.

7. The ceramic salt core for high-pressure casting of refrigerant flow channel plate according to claim 6, characterized in that, During the ball milling process, the ball milling speed is 350-400 r / min, the grinding balls are made of zirconium oxide, and the ball-to-material ratio is 10:1.