Silicon-based ceramic cores with intensity controlled by angular-to-spherical ratio and their preparation method

Abstract

The present invention discloses a silicon-based ceramic core and a preparation method thereof for regulating strength based on angular ratio. The mass percentage of each substance in the silicon-based ceramic core is 75-90wt% of ceramic powder and 10-25wt% of plasticizer. The mass percentage of each substance in the ceramic powder is 67-85wt% of quartz glass powder, 13-32wt% of mineralizer, and 0.1-2wt% of pore-forming material. The method comprises the following steps: pre-treating spherical powder in quartz glass powder of each particle size and alumina of each particle size; pre-treating quartz glass powder of each particle size and alumina of each particle size according to the designed angular ratio; mixing ceramic powder and plasticizer evenly to obtain silicon-based ceramic core slurry; injection molding to obtain a silicon-based ceramic core blank, and obtaining a silicon-based ceramic core based on angular ratio regulation strength after roasting. The present invention can obtain a series of silicon-based ceramic core systems with nearly linearly adjustable strength to meet different requirements for ceramic core strength in different working conditions, different inner cavity structures, different alloy types, etc. of blade investment casting.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramic core material design and preparation, and specifically relates to a silicon-based ceramic core with strength controlled based on angular ball ratio and a preparation method thereof. Background Art

[0002] In the precision casting of hollow turbine blades of aircraft engines, the ceramic core is the key component for the inner cavity of the blade. The ceramic core should have a certain room temperature strength and high temperature strength to ensure that it can withstand various types of forces without fracture failure during the preparation and service process, including the mechanical force of core repair, the impact force of wax pressing, the stress of interference positioning in the die, the impact force of high-temperature metal pouring, etc.; but at the same time, the high temperature strength of the ceramic core should not be too high to avoid thermal tearing or recrystallization of the inner cavity of the high-temperature alloy casting.

[0003] Therefore, the room temperature strength and high temperature strength of the ceramic core should not be too high or too low, but need to be adjusted according to the working conditions of the hollow blade structure and the casting environment. Therefore, it is urgent to develop a series of ceramic core material systems with nearly linearly adjustable strength to meet the needs of precision casting of hollow turbine blades of different models.

[0004] Silicon-based ceramic cores are widely used because of their good yieldability, removability and thermal shock resistance. However, there are still some problems in the existing methods for regulating the room temperature strength and high temperature strength of silicon-based ceramic cores: (1) By adjusting the type and ratio of mineralizers in the raw materials of the ceramic core, such as alumina, mullite, silicon nitride, etc., the content of the reinforcing phase and the fracture mechanism of the ceramic core can be changed, thereby regulating the room temperature strength and high temperature strength of the silicon-based ceramic core; however, the disadvantage of this method is that different types of mineralizers have different strengthening mechanisms, which leads to large differences in the strength of the ceramic core with temperature changes, making it difficult to form a ceramic core material system with nearly linearly adjustable strength. (2) By adjusting the particle grading of quartz glass powder or mineralizer in the raw materials of the ceramic core, the microscopic skeleton structure and sintering strength of the silicon-based ceramic core can be changed, thereby regulating the room temperature strength and high temperature strength of the silicon-based ceramic core; however, the disadvantage of this method is that the regulation of particle grading will cause grading conflicts, which will have an adverse effect on the fluidity of the ceramic core slurry.

[0005] The invention patent with application publication number CN105174722A discloses a ceramic core material with added quartz glass spherical powder. The weight percentage of the material formula is: zircon sand powder 0-30%, white corundum powder 0-30%, mullite powder 0-30%, quartz glass spherical powder 0.5-60%, and the balance is quartz glass powder; the median particle size of the quartz glass spherical powder is 3.5-50μm. This technical solution controls the sintering shrinkage of the ceramic core by adjusting the addition amount and powder particle size of the quartz glass spherical powder. Although it does not affect the room temperature strength and high temperature strength of the ceramic core, it cannot regulate the room temperature strength and high temperature strength, and cannot form a ceramic core material system with nearly linearly adjustable strength. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention provides a silicon-based ceramic core with strength regulated based on angular ball ratio, wherein the mass percentage of each substance in the silicon-based ceramic core is 75-90wt% of ceramic powder and 10-25wt% of plasticizer; the mass percentage of each substance in the ceramic powder is 67-85wt% of quartz glass powder, 13-32wt% of mineralizer and 0.1-2wt% of pore-forming material; the strength of the silicon-based ceramic core is regulated by adjusting the angular ball ratio of quartz glass powder of each particle size and the angular ball ratio of alumina of each particle size in the mineralizer, thereby forming a silicon-based ceramic core material system with nearly linearly adjustable strength.

[0007] Preferably, the quartz glass powder includes four particle sizes, namely 35-62 μm, 13-35 μm, 3-13 μm, and 0.05-3 μm; the mass percentage of each particle size in the quartz glass powder is as follows: 35-62 μm accounts for 45-60 wt%, 13-35 μm accounts for 10-25 wt%, 3-13 μm accounts for 20-30 wt%, and 0.05-3 μm accounts for 1-5 wt%.

[0008] In any of the above schemes, it is preferred that the mass percentage of each substance in the mineralizer is 30-40wt% of mullite, 40-58wt% of alumina, 5-15wt% of zirconium silicate, and 1-5wt% of titanium dioxide.

[0009] In any of the above schemes, it is preferred that the mullite is composed of mullite chopped fibers and mullite particles, and the mass percentages of the mullite chopped fibers and the mullite particles are 7-21wt% and 79-93wt%, respectively; the length of the mullite chopped fibers is 18-45μm and the diameter is 100-170nm; the mullite particles include four particle sizes, namely 50-70μm, 30-50μm, 15-30μm, and 3-15μm, and the mass percentage of each particle size in the mullite particles is 49-65wt% for a particle size of 50-70μm, 20-25wt% for a particle size of 30-50μm, 10-20wt% for a particle size of 15-30μm, and 1-7wt% for a particle size of 3-15μm.

[0010] In any of the above schemes, it is preferred that the aluminum oxide includes four particle sizes, namely 42-65μm, 18-42μm, 3-18μm, and 0.05-3μm; the mass percentage of each particle size in the aluminum oxide is 45-60wt% for 42-65μm, 10-25wt% for 18-42μm, 20-30wt% for 3-18μm, and 1-5wt% for 0.05-3μm.

[0011] In any of the above schemes, it is preferred that the zirconium silicate includes three particle sizes, namely 45-58μm, 38-45μm, and 18-38μm, and the mass percentage of each particle size in the zirconium silicate is: 45-58μm accounts for 40-55wt%, 38-45μm accounts for 25-35wt%, and 18-38μm accounts for 20-25wt%.

[0012] In any of the above schemes, preferably, the titanium dioxide has a particle size of 13-18 μm.

[0013] In any of the above schemes, it is preferred that the angular ball ratio of the quartz glass powder of each particle size is adjusted, and the angular ball ratio is the mass ratio of angular powder to spherical powder, wherein the quartz glass powder with a particle size of 35-62 μm has a angular ball ratio of 30-50:50-70, the quartz glass powder with a particle size of 13-35 μm has a angular ball ratio of 80-90:10-20, the quartz glass powder with a particle size of 3-13 μm has a angular ball ratio of 85-95:5-15, and the quartz glass powder with a particle size of 0.05-3 μm has a angular ball ratio of 95-99:1-5.

[0014] In any of the above schemes, it is preferred to adjust the angular ball ratio of alumina of each particle size in the mineralizer, wherein the angular ball ratio is the mass ratio of angular powder to spherical powder, wherein the angular ball ratio of alumina with a particle size of 42-65 μm is 15-50:50-85, the angular ball ratio of alumina with a particle size of 18-42 μm is 25-50:50-75, the angular ball ratio of alumina with a particle size of 3-18 μm is 50-75:25-50, and the angular ball ratio of alumina with a particle size of 0.05-3 μm is 85-99:1-15.

[0015] In any of the above schemes, preferably, the pore-forming material includes any one or more of graphite, graphene, starch, and carbon nanotubes.

[0016] In any of the above schemes, it is preferred that the mass percentage of each substance in the plasticizer is 80-90wt% of the adhesive, 3-10wt% of the plasticizer, and 2-10wt% of the surfactant; the adhesive includes any one or more of paraffin, beeswax, and ozokerite; the plasticizer is low-density polyethylene and / or cellulose; the surfactant includes any one or more of stearic acid, oleic acid, sodium stearate, and aluminum stearate.

[0017] The present invention also provides a method for preparing a silicon-based ceramic core with strength regulated by angular ratio, which is used to prepare any of the above-mentioned silicon-based ceramic cores with strength regulated by angular ratio, and comprises the following steps in order:

[0018] Step 1: Weigh all raw materials according to the designed material ratio;

[0019] Step 2: pre-treating the spherical powder in the quartz glass powder of each particle size respectively, and pre-treating the spherical powder in the alumina powder of each particle size respectively;

[0020] Step 3: according to the designed angular-spherical ratio of the quartz glass powder of each particle size, the angular powder in each particle size and the pretreated spherical powder are mixed evenly to obtain quartz glass powder of each particle size, and then the quartz glass powder of each particle size is pretreated;

[0021] Step 4: according to the designed angular-spherical ratio of aluminum oxide of each particle size, the angular powder in each particle size and the pretreated spherical powder are mixed evenly to obtain aluminum oxide of each particle size, and then the aluminum oxide of each particle size is pretreated;

[0022] Step 5: Put the pretreated quartz glass powder of various particle sizes, the pretreated alumina of various particle sizes, the mullite of various particle sizes, the zirconium silicate of various particle sizes, the titanium dioxide, and the pore-forming material into a V-type mixer and mix them evenly to obtain ceramic powder;

[0023] Step 6: According to the designed material ratio, the three components of the plasticizer, namely, the adhesive, the plasticizer, and the surfactant, are placed in a blender for heating and stirring, so that the adhesive, the plasticizer, and the surfactant are completely blended to obtain the plasticizer;

[0024] Step 7: Put the ceramic powder and the plasticizer into a mixer according to the designed material ratio, heat and stir them, so that the ceramic powder and the plasticizer are evenly mixed to obtain a silicon-based ceramic core slurry;

[0025] Step 8: manufacturing a ceramic core mold according to the designed ceramic core structure, injecting the silicon-based ceramic core slurry into the ceramic core mold by an injection molding machine for filling and pressing to obtain a silicon-based ceramic core blank;

[0026] Step 9: After checking the silicon-based ceramic core blank and confirming that there are no obvious defects in its appearance, the silicon-based ceramic core blank is inserted into a calcined pot filled with kaolin filler, and the kaolin filler completely covers the silicon-based ceramic core blank;

[0027] Step 10: Place the calcining pot containing the kaolin filler and the silicon-based ceramic core blank into a calcining furnace for calcining. After the calcining is completed, a silicon-based ceramic core with strength regulated based on the angle ratio can be obtained.

[0028] Preferably, in step 2, the pretreatment of the spherical powder in the quartz glass powder of each particle size comprises the following steps in order:

[0029] Step (2-1): immersing the spherical powders in the quartz glass powders of different particle sizes in the silica sol respectively, the immersion temperature is all at room temperature, the immersion time is all 1-3 hours, and after the immersion is completed, the spherical powders are filtered out;

[0030] Step (2-2): putting the spherical powders in the quartz glass powders of different particle sizes into ball mills respectively, adding deionized water and zirconium oxide ball milling beads into the ball mills, wherein the mass ratio of the spherical powder to the deionized water is 1:3, the mass ratio of the spherical powder to the zirconium oxide ball milling beads is 1:1, and the diameter of the zirconium oxide ball milling beads is 3 mm, and then putting the ball mills into a planetary ball mill for the first ball milling, wherein the ball milling speed is 180-220 r / min, and the ball milling time is 1-3 h;

[0031] Step (2-3): After the first ball milling is completed, the spherical powder, deionized water and zirconium oxide ball milling beads are taken out from the ball milling jar and separated, and then the operation of step (2-2) is repeated to perform the second ball milling;

[0032] Step (2-4): After the second ball milling is completed, the spherical powder is taken out from the ball mill jar and then placed in a blast drying oven for drying. The drying temperature is 110-130°C and the drying time is 6-8h.

[0033] In any of the above schemes, preferably, in step 2, the pretreatment of the spherical powder in the alumina of each particle size comprises the following steps in order:

[0034] Step (2-a): immersing the spherical powders of alumina of different particle sizes in silica sol respectively, at room temperature for 1-3 hours, and filtering out the spherical powders after the immersion is completed;

[0035] Step (2-b): putting the spherical powders of alumina of different particle sizes into ball mills respectively, adding deionized water and zirconium oxide ball milling beads into the ball mills, wherein the mass ratio of the spherical powder to the deionized water is 1:3, the mass ratio of the spherical powder to the zirconium oxide ball milling beads is 1:1, and the diameter of the zirconium oxide ball milling beads is 3 mm, and then putting the ball mills into a planetary ball mill for the first ball milling, wherein the ball milling speed is 180-220 r / min, and the ball milling time is 1-3 h;

[0036] Step (2-c): After the first ball milling is completed, the spherical powder, deionized water and zirconium oxide ball milling beads are taken out from the ball milling jar and separated, and then the operation of step (2-b) is repeated to perform the second ball milling;

[0037] Step (2-d): After the second ball milling is completed, the spherical powder is taken out from the ball mill, and then placed in a blast drying oven for drying. The drying temperature is 110-130° C. and the drying time is 6-8 h.

[0038] In any of the above schemes, preferably, in step 3, the pretreatment of the quartz glass powder of each particle size comprises the following steps in order:

[0039] Step (3-1): placing quartz glass powders of various particle sizes into ball mills respectively, adding deionized water and zirconium oxide ball milling beads into the ball mills, wherein the mass ratio of quartz glass powder to deionized water is 1:1, the mass ratio of quartz glass powder to zirconium oxide ball milling beads is 1:1, and the diameter of the zirconium oxide ball milling beads is 3 mm, and then placing the ball mills into a planetary ball mill for ball milling, the ball milling speed is 320-380 r / min, and the ball milling time is 4-8 h;

[0040] Step (3-2): After the ball milling is completed, the quartz glass powder is taken out from the ball mill jar and then placed in a blast drying oven for drying. The drying temperature is 110-130°C and the drying time is 6-8h.

[0041] In any of the above schemes, preferably, in step 4, the pretreatment of aluminum oxide of each particle size comprises the following steps in order:

[0042] Step (4-1): placing aluminum oxide of various particle sizes into a ball mill respectively, adding deionized water and zirconium oxide ball milling beads into the ball mill, wherein the mass ratio of aluminum oxide to deionized water is 1:1, the mass ratio of aluminum oxide to zirconium oxide ball milling beads is 1:1, and the diameter of the zirconium oxide ball milling beads is 3 mm, and then placing the ball mill into a planetary ball mill for ball milling, the ball milling speed is 320-380 r / min, and the ball milling time is 4-8 h;

[0043] Step (4-2): After the ball milling is completed, the alumina is taken out from the ball mill jar and then placed in a blast drying oven for drying. The drying temperature is 110-130°C and the drying time is 6-8h.

[0044] In any of the above schemes, preferably, in step five, the mixing speed of the quartz glass powder of each particle size after pretreatment, the alumina of each particle size after pretreatment, the mullite of each particle size, the zirconium silicate of each particle size, the titanium dioxide, and the pore-forming material is 20-50 r / min and the mixing time is 6-10 h.

[0045] In any of the above schemes, preferably, in step six, the stirring temperature of the adhesive, plasticizer and surfactant is 60-200° C., the stirring speed is 100-200 r / min, and the stirring time is 1-4 h.

[0046] In any of the above schemes, preferably, in step seven, the stirring temperature of the ceramic powder and the plasticizer is 60-200° C., the stirring speed is 300-500 r / min, and the stirring time is 20-24 h.

[0047] In any of the above schemes, preferably, in step eight, the pressing parameters of the silicon-based ceramic core blank are injection temperature 60-105° C., injection speed 100-120 cc / s, injection pressure 6-10 MPa, and holding time 10-40 s.

[0048] In any of the above schemes, preferably, in step ten, the sintering parameters of the silicon-based ceramic core blank are a final sintering temperature of 1150-1300° C. and a sintering time of 43-59 h.

[0049] In the present invention, the V-shaped mixer, agitator, injection molding machine, roasting furnace, etc. used are all traditional equipment, and there are no special requirements for the equipment structure and model. The manufacturing process of the ceramic core mold is a traditional process, and there are no special requirements for the process flow, process parameters, mold materials, manufacturing equipment, etc. The pressing process of the ceramic core blank is also a traditional process, and there are no special requirements for the process flow, process parameters, pressing equipment, etc. It only needs to ensure that several key pressing parameters such as injection temperature, injection speed, injection pressure, and holding time meet the requirements of the present invention.

[0050] In the present invention, the quartz glass powder includes four particle sizes, namely 35-62μm, 13-35μm, 3-13μm, and 0.05-3μm, that is, 35μm≤particle size<62μm, 13μm≤particle size<35μm, 3μm≤particle size<13μm, and 0.05μm≤particle size<3μm; the mullite particles include four particle sizes, namely 50-70μm, 30-50μm, 15-30μm, and 3-15μm, that is, 50μm≤particle size<70μm, 30μm≤particle size<50μm, 15μm≤particle size<30μm, and 3μm≤particle size<15μm; the alumina It includes four particle sizes, namely 42-65μm, 18-42μm, 3-18μm, and 0.05-3μm, that is, 42μm≤particle size<65μm, 18μm≤particle size<42μm, 3μm≤particle size<18μm, and 0.05μm≤particle size<3μm; zirconium silicate includes three particle sizes, namely 45-58μm, 38-45μm, and 18-38μm, that is, 45μm≤particle size<58μm, 38μm≤particle size<45μm, and 18μm≤particle size<38μm; titanium dioxide includes one particle size, which is 13-18μm, that is, 13μm≤particle size<18μm. For each particle size, the material passes through the upper and lower sieve holes in sequence to obtain a material with a particle size between the upper and lower sieve holes, for example: the particle size is 30-50μm (30μm≤particle size<50μm), that is, the material passes through the 50μm sieve hole and the 30μm sieve hole in sequence to obtain a material with a particle size between 30-50μm.

[0051] In the present invention, the mineralizer can promote the sintering of the silicon-based ceramic core and the phase transition of quartz; the pore-forming material can form pores inside the silicon-based ceramic core, which is convenient for the subsequent dissolution and removal of the core; the spherical powder in the quartz glass powder of each particle size and the spherical powder in the alumina of each particle size need to be ball-milled twice, the purpose of which is to remove the excess silica sol attached to the spherical powder.

[0052] In the present invention, the explanation of nearly linear adjustable strength is that the strength of the silicon-based ceramic core is regulated by adjusting the angular ratio of the quartz glass powder of each particle size and the angular ratio of the alumina of each particle size in the mineralizer, so as to form a series of silicon-based ceramic core formulas with nearly equidistant strength, that is, the series of silicon-based ceramic core formulas formed correspond to a series of strengths, and this series of strengths is evenly distributed within a certain range. Angular powder is a powder particle with sharp protrusions and indentations (low roundness), and a large difference between the major axis and the minor axis (low sphericity); spherical powder is a powder particle with a rounded appearance (high roundness), and the major axis and the minor axis are basically the same (high sphericity).

[0053] In the present invention, during the entire preparation process of the silicon-based ceramic core, the angular ball ratio of quartz glass powder of each particle size, the angular ball ratio of alumina of each particle size, the pretreatment system of spherical powder in quartz glass powder of each particle size, the pretreatment system of spherical powder in alumina of each particle size, the pretreatment system of quartz glass powder of each particle size, the pretreatment system of alumina of each particle size, etc. are all very important, and each parameter needs to work synergistically to achieve the expected technical effect of the present invention.

[0054] The technical principle of the present invention is: (1) For spherical powder and angular powder of the same particle size, the spherical powder has a high degree of roundness and no small-sized sharp corners on the surface, so the driving force required for sintering is greater, it is difficult to form a sintering neck, and the sintering degree is lower under the same sintering system, so the strength of the ceramic core is lower and it is not easy to produce recrystallization; as the angle-to-ball ratio decreases, the strength of the ceramic core decreases accordingly. (2) For quartz glass powder or alumina of the same particle type, the sintering driving force of the large particle size is greater and the sintering degree is lower; reducing the angle-to-ball ratio of the coarse powder in the quartz glass powder and / or alumina reduces the degree of strength reduction to a lesser extent, and reducing the angle-to-ball ratio of the fine powder in the quartz glass powder and / or alumina reduces the degree of strength reduction to a greater extent. The present invention discloses a silicon-based ceramic core with strength controlled by angular ball ratio and a preparation method thereof, which has the following beneficial effects: based on a certain type, ratio and particle grading of ceramic powder, a series of silicon-based ceramic core material systems with nearly linearly adjustable room temperature strength and high temperature strength can be obtained by only adjusting the angular ball ratio of quartz glass powder of various particle sizes and the angular ball ratio of alumina of various particle sizes in a mineralizer, which can meet different requirements for ceramic core strength under different working conditions, different inner cavity structures, different alloy types and the like in investment casting of hollow blades of aircraft engines turbines, reduce problems such as recrystallization, core breakage, core leakage and core eccentricity of turbine blades caused by excessively high or low strength of the ceramic core, and can control the changes in sintering shrinkage and secondary shrinkage of the ceramic core within a relatively small range. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a flow chart of a preferred embodiment of a silicon-based ceramic core and a preparation method thereof for controlling strength based on angular ball ratio according to the present invention;

[0056] Figure 2 for Figure 1 The microscopic morphology of the angular powder in the quartz glass powder of the embodiment shown;

[0057] Figure 3 for Figure 1 The microscopic morphology of the spherical powder in the quartz glass powder of the embodiment shown;

[0058] Figure 4 for Figure 1 Schematic diagram of the sintering mechanism of angular powder and spherical powder in the illustrated embodiment;

[0059] Figure 5 for Figure 1 The microscopic morphology of formula 1 in the silicon-based ceramic core material system prepared in the illustrated embodiment;

[0060] Figure 6 for Figure 1 The microscopic morphology of formula 3 in the silicon-based ceramic core material system prepared in the illustrated embodiment;

[0061] Figure 7 for Figure 1 The microscopic morphology of formula 8 in the silicon-based ceramic core material system prepared in the illustrated embodiment;

[0062] Figure 8 for Figure 1 The microscopic morphology of formula 13 in the silicon-based ceramic core material system prepared in the illustrated embodiment;

[0063] Fig. 9 for Figure 1 The room temperature three-point bending strength test results of the silicon-based ceramic core material system (formulations 1-13) prepared in the examples shown;

[0064] Fig.10 for Figure 1 The high temperature three-point bending strength test results of the silicon-based ceramic core material system (formulations 1-13) prepared in the examples shown;

[0065] Fig.11 for Figure 1 The sintering shrinkage and total yield test results of the silicon-based ceramic core material system (formulations 1-13) prepared in the examples shown.

[0066] Notes in the figure: 1-angular powder, 2-spherical powder, 3-sintering neck. DETAILED DESCRIPTION

[0067] In order to further understand the content of the present invention, the present invention will be described in detail below in conjunction with specific embodiments.

[0068] Embodiment 1:

[0069] According to a preferred embodiment of the silicon-based ceramic core with strength controlled by angular ball ratio of the present invention, the mass percentage of each substance in the silicon-based ceramic core is 85wt% of ceramic powder and 15wt% of plasticizer; the mass percentage of each substance in the ceramic powder is 76wt% of quartz glass powder, 23wt% of mineralizer and 1wt% of pore-forming material; the strength of the silicon-based ceramic core is controlled by adjusting the angular ball ratio of quartz glass powder of each particle size and the angular ball ratio of alumina of each particle size in the mineralizer, thereby forming a silicon-based ceramic core material system with nearly linearly adjustable strength.

[0070] The quartz glass powder includes four particle sizes, namely 35-62μm, 13-35μm, 3-13μm, and 0.05-3μm; the mass percentage of each particle size in the quartz glass powder is as follows: 35-62μm accounts for 52wt%, 13-35μm accounts for 20wt%, 3-13μm accounts for 25wt%, and 0.05-3μm accounts for 3wt%.

[0071] The mass percentage of each substance in the mineralizer is 35wt% of mullite, 50wt% of aluminum oxide, 12wt% of zirconium silicate, and 3wt% of titanium dioxide.

[0072] The mullite is composed of mullite chopped fibers and mullite particles, and the mullite chopped fibers and the mullite particles account for 14wt% and 86wt% of the mass percentage of the mullite respectively; the length of the mullite chopped fibers is 31μm and the diameter is 135nm; the mullite particles include four particle sizes, namely 50-70μm, 30-50μm, 15-30μm, and 3-15μm, and the mass percentage of each particle size in the mullite particles is 58wt% for 50-70μm, 23wt% for 30-50μm, 15wt% for 15-30μm, and 4wt% for 3-15μm.

[0073] The aluminum oxide includes four particle sizes, namely 42-65 μm, 18-42 μm, 3-18 μm, and 0.05-3 μm; the mass percentage of each particle size in the aluminum oxide is: 42-65 μm accounts for 52wt%, 18-42 μm accounts for 20wt%, 3-18 μm accounts for 25wt%, and 0.05-3 μm accounts for 3wt%.

[0074] The zirconium silicate includes three particle sizes, namely 45-58 μm, 38-45 μm, and 18-38 μm, and the mass percentage of each particle size in the zirconium silicate is 48wt% for particle size 45-58 μm, 30wt% for particle size 38-45 μm, and 22wt% for particle size 18-38 μm. The titanium dioxide includes a particle size of 13-18 μm. The pore-forming material is graphene.

[0075] The mass percentages of the substances in the plasticizer are as follows: 86wt% of the adhesive, 7wt% of the plasticizer, and 7wt% of the surfactant; the adhesive is paraffin; the plasticizer is low-density polyethylene; and the surfactant is sodium stearate.

[0076] In this embodiment, the strength of the silicon-based ceramic core is regulated by adjusting the angular-sphere ratio of the quartz glass powder of each particle size and the angular-sphere ratio of the alumina of each particle size in the mineralizer, so as to form a series of silicon-based ceramic core formulas with strengths close to arithmetic arrangement, that is, the series of silicon-based ceramic core formulas formed correspond to a series of strengths, and the series of strengths are evenly distributed within a certain range. The angular-sphere ratio is the mass ratio of the angular powder to the spherical powder.

[0077] (1) Adjust the angle ratio of quartz glass powder of different particle sizes, wherein the angle ratio of quartz glass powder with a particle size of 35-62 μm is 30-50:50-70, the angle ratio of quartz glass powder with a particle size of 13-35 μm is 80-90:10-20, the angle ratio of quartz glass powder with a particle size of 3-13 μm is 85-95:5-15, and the angle ratio of quartz glass powder with a particle size of 0.05-3 μm is 95-99:1-5.

[0078] (2) Adjust the angular ratio of alumina of different particle sizes in the mineralizer, wherein the angular ratio of alumina with a particle size of 42-65 μm is 15-50:50-85, the angular ratio of alumina with a particle size of 18-42 μm is 25-50:50-75, the angular ratio of alumina with a particle size of 3-18 μm is 50-75:25-50, and the angular ratio of alumina with a particle size of 0.05-3 μm is 85-99:1-15.

[0079] A series of silicon-based ceramic core formulas are formed by taking values ​​within the above-mentioned angular ball ratio range of the quartz glass powder of each particle size and the angular ball ratio range of the alumina of each particle size, as follows:

[0080] Formula 1: The angle ratio of quartz glass powder with a particle size of 35-62μm is 50:50, the angle ratio of quartz glass powder with a particle size of 13-35μm is 90:10, the angle ratio of quartz glass powder with a particle size of 3-13μm is 95:5, and the angle ratio of quartz glass powder with a particle size of 0.05-3μm is 99:1. The angle ratio of aluminum oxide with a particle size of 42-65μm is 50:50, the angle ratio of aluminum oxide with a particle size of 18-42μm is 50:50, the angle ratio of aluminum oxide with a particle size of 3-18μm is 75:25, and the angle ratio of aluminum oxide with a particle size of 0.05-3μm is 99:1.

[0081] Formula 2: The angular ball ratio of quartz glass powder with a particle size of 35-62μm is 30:70, the angular ball ratio of quartz glass powder with a particle size of 13-35μm is 90:10, the angular ball ratio of quartz glass powder with a particle size of 3-13μm is 95:5, and the angular ball ratio of quartz glass powder with a particle size of 0.05-3μm is 99:1. The angular ball ratio of aluminum oxide with a particle size of 42-65μm is 50:50, the angular ball ratio of aluminum oxide with a particle size of 18-42μm is 50:50, the angular ball ratio of aluminum oxide with a particle size of 3-18μm is 75:25, and the angular ball ratio of aluminum oxide with a particle size of 0.05-3μm is 99:1.

[0082] Formula 3: The angle ratio of quartz glass powder with a particle size of 35-62μm is 50:50, the angle ratio of quartz glass powder with a particle size of 13-35μm is 80:20, the angle ratio of quartz glass powder with a particle size of 3-13μm is 95:5, and the angle ratio of quartz glass powder with a particle size of 0.05-3μm is 99:1. The angle ratio of aluminum oxide with a particle size of 42-65μm is 50:50, the angle ratio of aluminum oxide with a particle size of 18-42μm is 50:50, the angle ratio of aluminum oxide with a particle size of 3-18μm is 75:25, and the angle ratio of aluminum oxide with a particle size of 0.05-3μm is 99:1.

[0083] Formula 4: The angular ball ratio of quartz glass powder with a particle size of 35-62μm is 30:70, the angular ball ratio of quartz glass powder with a particle size of 13-35μm is 80:20, the angular ball ratio of quartz glass powder with a particle size of 3-13μm is 95:5, and the angular ball ratio of quartz glass powder with a particle size of 0.05-3μm is 99:1. The angular ball ratio of aluminum oxide with a particle size of 42-65μm is 50:50, the angular ball ratio of aluminum oxide with a particle size of 18-42μm is 50:50, the angular ball ratio of aluminum oxide with a particle size of 3-18μm is 75:25, and the angular ball ratio of aluminum oxide with a particle size of 0.05-3μm is 99:1.

[0084] Formula 5: The angular ball ratio of quartz glass powder with a particle size of 35-62μm is 30:70, the angular ball ratio of quartz glass powder with a particle size of 13-35μm is 80:20, the angular ball ratio of quartz glass powder with a particle size of 3-13μm is 85:15, and the angular ball ratio of quartz glass powder with a particle size of 0.05-3μm is 99:1. The angular ball ratio of aluminum oxide with a particle size of 42-65μm is 50:50, the angular ball ratio of aluminum oxide with a particle size of 18-42μm is 50:50, the angular ball ratio of aluminum oxide with a particle size of 3-18μm is 75:25, and the angular ball ratio of aluminum oxide with a particle size of 0.05-3μm is 99:1.

[0085] Formula 6: The angle ratio of quartz glass powder with a particle size of 35-62μm is 50:50, the angle ratio of quartz glass powder with a particle size of 13-35μm is 80:20, the angle ratio of quartz glass powder with a particle size of 3-13μm is 85:15, and the angle ratio of quartz glass powder with a particle size of 0.05-3μm is 95:5. The angle ratio of aluminum oxide with a particle size of 42-65μm is 50:50, the angle ratio of aluminum oxide with a particle size of 18-42μm is 50:50, the angle ratio of aluminum oxide with a particle size of 3-18μm is 75:25, and the angle ratio of aluminum oxide with a particle size of 0.05-3μm is 99:1.

[0086] Formula 7: The angle ratio of quartz glass powder with a particle size of 35-62μm is 30:70, the angle ratio of quartz glass powder with a particle size of 13-35μm is 80:20, the angle ratio of quartz glass powder with a particle size of 3-13μm is 85:15, and the angle ratio of quartz glass powder with a particle size of 0.05-3μm is 95:5. The angle ratio of aluminum oxide with a particle size of 42-65μm is 50:50, the angle ratio of aluminum oxide with a particle size of 18-42μm is 50:50, the angle ratio of aluminum oxide with a particle size of 3-18μm is 75:25, and the angle ratio of aluminum oxide with a particle size of 0.05-3μm is 99:1.

[0087] Formula 8: The angle ratio of quartz glass powder with a particle size of 35-62μm is 30:70, the angle ratio of quartz glass powder with a particle size of 13-35μm is 80:20, the angle ratio of quartz glass powder with a particle size of 3-13μm is 85:15, and the angle ratio of quartz glass powder with a particle size of 0.05-3μm is 95:5. The angle ratio of aluminum oxide with a particle size of 42-65μm is 15:85, the angle ratio of aluminum oxide with a particle size of 18-42μm is 50:50, the angle ratio of aluminum oxide with a particle size of 3-18μm is 75:25, and the angle ratio of aluminum oxide with a particle size of 0.05-3μm is 99:1.

[0088] Formula 9: The angle ratio of quartz glass powder with a particle size of 35-62μm is 30:70, the angle ratio of quartz glass powder with a particle size of 13-35μm is 80:20, the angle ratio of quartz glass powder with a particle size of 3-13μm is 85:15, and the angle ratio of quartz glass powder with a particle size of 0.05-3μm is 95:5. The angle ratio of aluminum oxide with a particle size of 42-65μm is 50:50, the angle ratio of aluminum oxide with a particle size of 18-42μm is 25:75, the angle ratio of aluminum oxide with a particle size of 3-18μm is 75:25, and the angle ratio of aluminum oxide with a particle size of 0.05-3μm is 99:1.

[0089] Formula 10: The angle ratio of quartz glass powder with a particle size of 35-62μm is 30:70, the angle ratio of quartz glass powder with a particle size of 13-35μm is 80:20, the angle ratio of quartz glass powder with a particle size of 3-13μm is 85:15, and the angle ratio of quartz glass powder with a particle size of 0.05-3μm is 95:5. The angle ratio of aluminum oxide with a particle size of 42-65μm is 15:85, the angle ratio of aluminum oxide with a particle size of 18-42μm is 25:75, the angle ratio of aluminum oxide with a particle size of 3-18μm is 75:25, and the angle ratio of aluminum oxide with a particle size of 0.05-3μm is 99:1.

[0090] Formula 11: The angular ball ratio of quartz glass powder with a particle size of 35-62μm is 30:70, the angular ball ratio of quartz glass powder with a particle size of 13-35μm is 80:20, the angular ball ratio of quartz glass powder with a particle size of 3-13μm is 85:15, and the angular ball ratio of quartz glass powder with a particle size of 0.05-3μm is 95:5. The angular ball ratio of aluminum oxide with a particle size of 42-65μm is 15:85, the angular ball ratio of aluminum oxide with a particle size of 18-42μm is 25:75, the angular ball ratio of aluminum oxide with a particle size of 3-18μm is 50:50, and the angular ball ratio of aluminum oxide with a particle size of 0.05-3μm is 99:1.

[0091] Formula 12: The angle ratio of quartz glass powder with a particle size of 35-62μm is 30:70, the angle ratio of quartz glass powder with a particle size of 13-35μm is 80:20, the angle ratio of quartz glass powder with a particle size of 3-13μm is 85:15, and the angle ratio of quartz glass powder with a particle size of 0.05-3μm is 95:5. The angle ratio of aluminum oxide with a particle size of 42-65μm is 50:50, the angle ratio of aluminum oxide with a particle size of 18-42μm is 25:75, the angle ratio of aluminum oxide with a particle size of 3-18μm is 50:50, and the angle ratio of aluminum oxide with a particle size of 0.05-3μm is 99:1.

[0092] Formula 13: The angular ball ratio of quartz glass powder with a particle size of 35-62μm is 30:70, the angular ball ratio of quartz glass powder with a particle size of 13-35μm is 80:20, the angular ball ratio of quartz glass powder with a particle size of 3-13μm is 85:15, and the angular ball ratio of quartz glass powder with a particle size of 0.05-3μm is 95:5. The angular ball ratio of aluminum oxide with a particle size of 42-65μm is 15:85, the angular ball ratio of aluminum oxide with a particle size of 18-42μm is 25:75, the angular ball ratio of aluminum oxide with a particle size of 3-18μm is 50:50, and the angular ball ratio of aluminum oxide with a particle size of 0.05-3μm is 85:15.

[0093] like Figure 1As shown, this embodiment also provides a method for preparing a silicon-based ceramic core with strength regulated by angular ratio, which is used to prepare the above silicon-based ceramic core with strength regulated by angular ratio, and includes the following steps in order:

[0094] Step 1: Weigh all raw materials according to the designed material ratio;

[0095] Step 2: pre-treating the spherical powder in the quartz glass powder of each particle size respectively, and pre-treating the spherical powder in the alumina powder of each particle size respectively;

[0096] Step 3: according to the designed angular-spherical ratio of the quartz glass powder of each particle size, the angular powder in each particle size and the pretreated spherical powder are mixed evenly to obtain quartz glass powder of each particle size, and then the quartz glass powder of each particle size is pretreated;

[0097] Step 4: according to the designed angular-spherical ratio of aluminum oxide of each particle size, the angular powder in each particle size and the pretreated spherical powder are mixed evenly to obtain aluminum oxide of each particle size, and then the aluminum oxide of each particle size is pretreated;

[0098] Step 5: Put the pretreated quartz glass powder of various particle sizes, the pretreated alumina of various particle sizes, the mullite of various particle sizes, the zirconium silicate of various particle sizes, the titanium dioxide, and the pore-forming material into a V-type mixer and mix them evenly to obtain ceramic powder;

[0099] Step 6: According to the designed material ratio, the three components of the plasticizer, namely, the adhesive, the plasticizer, and the surfactant, are placed in a blender for heating and stirring, so that the adhesive, the plasticizer, and the surfactant are completely blended to obtain the plasticizer;

[0100] Step 7: Put the ceramic powder and the plasticizer into a mixer according to the designed material ratio, heat and stir them, so that the ceramic powder and the plasticizer are evenly mixed to obtain a silicon-based ceramic core slurry;

[0101] Step 8: manufacturing a ceramic core mold according to the designed ceramic core structure, injecting the silicon-based ceramic core slurry into the ceramic core mold by an injection molding machine for filling and pressing to obtain a silicon-based ceramic core blank;

[0102] Step 9: After checking the silicon-based ceramic core blank and confirming that there are no obvious defects in its appearance, the silicon-based ceramic core blank is inserted into a calcined pot filled with kaolin filler, and the kaolin filler completely covers the silicon-based ceramic core blank;

[0103] Step 10: Place the calcining pot containing the kaolin filler and the silicon-based ceramic core blank into a calcining furnace for calcining. After the calcining is completed, a silicon-based ceramic core with strength regulated based on the angle ratio can be obtained.

[0104] In step 2, the pretreatment of the spherical powder in the quartz glass powder of each particle size includes the following steps in order:

[0105] Step (2-1): immersing the spherical powders in the quartz glass powders of different particle sizes in the silica sol respectively, at room temperature for 2 hours, and filtering out the spherical powders after the immersion is completed;

[0106] Step (2-2): putting the spherical powders in the quartz glass powders of different particle sizes into ball mills respectively, adding deionized water and zirconium oxide ball milling beads into the ball mills, the mass ratio of the spherical powder to the deionized water is 1:3, the mass ratio of the spherical powder to the zirconium oxide ball milling beads is 1:1, the diameter of the zirconium oxide ball milling beads is 3 mm, and then putting the ball mills into a planetary ball mill for the first ball milling, the ball milling speed is 200 r / min, and the ball milling time is 2 h;

[0107] Step (2-3): After the first ball milling is completed, the spherical powder, deionized water and zirconium oxide ball milling beads are taken out from the ball milling jar and separated, and then the operation of step (2-2) is repeated to perform the second ball milling;

[0108] Step (2-4): After the second ball milling is completed, the spherical powder is taken out from the ball mill jar and then placed in a blast drying oven for drying. The drying temperature is 120° C. and the drying time is 7 h.

[0109] In step 2, the pretreatment of the spherical powder in the alumina of each particle size includes the following steps in order:

[0110] Step (2-a): immersing the spherical powders of alumina of different particle sizes in silica sol respectively, at room temperature for 2 hours, and filtering out the spherical powders after the immersion is completed;

[0111] Step (2-b): putting the spherical powders of alumina of different particle sizes into ball mills respectively, adding deionized water and zirconium oxide ball milling beads into the ball mills, wherein the mass ratio of the spherical powder to the deionized water is 1:3, the mass ratio of the spherical powder to the zirconium oxide ball milling beads is 1:1, and the diameter of the zirconium oxide ball milling beads is 3 mm, and then putting the ball mills into a planetary ball mill for the first ball milling, the ball milling speed is 200 r / min, and the ball milling time is 2 h;

[0112] Step (2-c): After the first ball milling is completed, the spherical powder, deionized water and zirconium oxide ball milling beads are taken out from the ball milling jar and separated, and then the operation of step (2-b) is repeated to perform the second ball milling;

[0113] Step (2-d): After the second ball milling is completed, the spherical powder is taken out from the ball mill jar and then placed in a blast drying oven for drying. The drying temperature is 120° C. and the drying time is 7 h.

[0114] In step 3, the pretreatment of the quartz glass powder of each particle size includes the following steps in order:

[0115] Step (3-1): placing quartz glass powders of various particle sizes into ball mills respectively, adding deionized water and zirconium oxide ball milling beads into the ball mills, wherein the mass ratio of quartz glass powder to deionized water is 1:1, the mass ratio of quartz glass powder to zirconium oxide ball milling beads is 1:1, and the diameter of the zirconium oxide ball milling beads is 3 mm, and then placing the ball mills into a planetary ball mill for ball milling, the ball milling speed is 350 r / min, and the ball milling time is 6 h;

[0116] Step (3-2): After the ball milling is completed, the quartz glass powder is taken out from the ball mill jar and then placed in a blast drying oven for drying. The drying temperature is 120° C. and the drying time is 7 h.

[0117] In step 4, the pretreatment of aluminum oxide of each particle size includes the following steps in order:

[0118] Step (4-1): placing aluminum oxide of various particle sizes into a ball mill respectively, adding deionized water and zirconium oxide ball milling beads into the ball mill, wherein the mass ratio of aluminum oxide to deionized water is 1:1, the mass ratio of aluminum oxide to zirconium oxide ball milling beads is 1:1, and the diameter of the zirconium oxide ball milling beads is 3 mm, and then placing the ball mill into a planetary ball mill for ball milling, the ball milling speed is 350 r / min, and the ball milling time is 6 h;

[0119] Step (4-2): After the ball milling is completed, the alumina is taken out from the ball mill jar and then placed in a forced air drying oven for drying. The drying temperature is 120°C and the drying time is 7 hours.

[0120] In step 5, the mixing speed of the pretreated quartz glass powder of various particle sizes, the pretreated alumina of various particle sizes, the mullite of various particle sizes, the zirconium silicate of various particle sizes, the titanium dioxide, and the pore-forming material is 35 r / min and the mixing time is 8 h.

[0121] In step six, the stirring temperature of the adhesive, plasticizer and surfactant is 130° C., the stirring speed is 150 r / min and the stirring time is 3 h.

[0122] In step seven, the stirring temperature of the ceramic powder and the plasticizer is 130° C., the stirring speed is 400 r / min, and the stirring time is 22 h.

[0123] In step eight, the pressing parameters of the silicon-based ceramic core blank are injection temperature 80° C., injection speed 110 cc / s, injection pressure 8 MPa, and holding time 25 s.

[0124] In step ten, the sintering parameters of the silicon-based ceramic core blank are a final sintering temperature of 1225° C. and a sintering time of 51 h.

[0125] In this embodiment, the microscopic morphology of the angular powder in the quartz glass powder is as follows: Figure 2 As shown in Figure 2, the microscopic morphology of spherical powder is as follows: Figure 3 As shown in Figure 2, the sintering mechanism of angular powder and spherical powder is as follows: Figure 4 As shown, the angular powder 1 and the spherical powder 2 are sintered to form a sintering neck 3. The typical microscopic morphology of the silicon-based ceramic core material system prepared in this embodiment is as follows: Figure 5-8 As shown, the microstructure of formula 1 is as follows: Figure 5 As shown, the microstructure of formula 3 is as follows Figure 6 As shown, the microstructure of formula 8 is as follows Figure 7 As shown, the microstructure of formula 13 is as follows Figure 8 shown.

[0126] According to the material formula and preparation process of this embodiment, a ceramic core test rod was prepared. The test rod size was 120mm×10mm×4mm. The room temperature three-point bending strength, high temperature three-point bending strength (1500°C), sintering shrinkage (shrinkage from wet state to sintered state), and total shrinkage (shrinkage from wet state to 1550°C) were tested. The test results are as follows: Figure 9-11 shown.

[0127] It can be seen from the figure that with the regulation of the angle ratio of quartz glass powder with different particle sizes and the angle ratio of alumina, the room temperature three-point bending strength and high temperature three-point bending strength of the silicon-based ceramic core series formula change linearly, and the sintering yield of the series formula

[0128] The shrinkage rate is controlled within 0.2% and the total shrinkage rate is controlled within 0.6%.

[0129] The silicon-based ceramic core with strength controlled by angular ball ratio and the preparation method thereof in the present embodiment have the following beneficial effects: based on a certain type, ratio and particle grading of ceramic powder, a series of silicon-based ceramic core material systems with nearly linearly adjustable room temperature strength and high temperature strength can be obtained by only adjusting the angular ball ratio of quartz glass powder of various particle sizes and the angular ball ratio of alumina of various particle sizes in the mineralizer, which can meet the different requirements for ceramic core strength under different working conditions, different inner cavity structures, different alloy types and the like in investment casting of hollow blades of aircraft engine turbines, reduce the problems of turbine blade recrystallization, core breakage, core leakage, core eccentricity caused by excessively high or low strength of the ceramic core, and can control the changes in sintering shrinkage and secondary shrinkage of the ceramic core within a relatively small range.

[0130] Embodiment 2:

[0131] According to another preferred embodiment of the silicon-based ceramic core and its preparation method for controlling strength based on angular ratio of the present invention, its material ratio, preparation process, technical principle, beneficial effects, etc. are basically the same as those of the first embodiment, except that:

[0132] The mass percentages of each substance in the silicon-based ceramic core are: 75wt% ceramic powder, 25wt% plasticizer; the mass percentages of each substance in the ceramic powder are: 67wt% quartz glass powder, 32wt% mineralizer, 1wt% pore-forming material; the mass percentages of each substance in the mineralizer are: 32wt% mullite, 58wt% alumina, 5wt% zirconium silicate, 5wt% titanium dioxide.

[0133] The quartz glass powder includes four particle sizes, namely 35-62μm, 13-35μm, 3-13μm, and 0.05-3μm; the mass percentage of each particle size in the quartz glass powder is as follows: 35-62μm accounts for 45wt%, 13-35μm accounts for 25wt%, 3-13μm accounts for 29wt%, and 0.05-3μm accounts for 1wt%.

[0134] The mullite is composed of mullite chopped fibers and mullite particles, and the mullite chopped fibers and the mullite particles account for 7wt% and 93wt% of the mass percentage of the mullite respectively; the length of the mullite chopped fibers is 18μm and the diameter is 100nm; the mullite particles include four particle sizes, namely 50-70μm, 30-50μm, 15-30μm, and 3-15μm, and the mass percentage of each particle size in the mullite particles is 49wt% for particle size 50-70μm, 25wt% for particle size 30-50μm, 20wt% for particle size 15-30μm, and 6wt% for particle size 3-15μm.

[0135] The aluminum oxide includes four particle sizes, namely 42-65μm, 18-42μm, 3-18μm, and 0.05-3μm; the mass percentage of each particle size in the aluminum oxide is: 42-65μm accounts for 45wt%, 18-42μm accounts for 25wt%, 3-18μm accounts for 29wt%, and 0.05-3μm accounts for 1wt%.

[0136] The zirconium silicate includes three particle sizes, namely 45-58 μm, 38-45 μm, and 18-38 μm, and the mass percentage of each particle size in the zirconium silicate is 40wt% for particle size 45-58 μm, 35wt% for particle size 38-45 μm, and 25wt% for particle size 18-38 μm. The titanium dioxide includes a particle size of 13-18 μm. The pore-forming material is selected from carbon nanotubes.

[0137] The mass percentages of the various substances in the plasticizer are 80wt% of the adhesive, 10wt% of the plasticizer, and 10wt% of the surfactant; the adhesive is beeswax; the plasticizer is low-density polyethylene; and the surfactant is aluminum stearate.

[0138] In this embodiment, the strength of the silicon-based ceramic core is regulated by adjusting the angular ball ratio of quartz glass powder of various particle sizes and the angular ball ratio of alumina of various particle sizes in the mineralizer, thereby forming a silicon-based ceramic core material system with nearly linearly adjustable strength.

[0139] (1) Adjust the angle ratio of quartz glass powder of different particle sizes, wherein the angle ratio of quartz glass powder with a particle size of 35-62 μm is 30-50:50-70, the angle ratio of quartz glass powder with a particle size of 13-35 μm is 80-90:10-20, the angle ratio of quartz glass powder with a particle size of 3-13 μm is 85-95:5-15, and the angle ratio of quartz glass powder with a particle size of 0.05-3 μm is 95-99:1-5.

[0140] (2) Adjust the angular ratio of alumina of different particle sizes in the mineralizer, wherein the angular ratio of alumina with a particle size of 42-65 μm is 15-50:50-85, the angular ratio of alumina with a particle size of 18-42 μm is 25-50:50-75, the angular ratio of alumina with a particle size of 3-18 μm is 50-75:25-50, and the angular ratio of alumina with a particle size of 0.05-3 μm is 85-99:1-15.

[0141] In step 2, the pretreatment process parameters of the spherical powder in the quartz glass powder of each particle size are: the immersion time is 1h; the first ball milling treatment, the ball milling speed is 180r / min, the ball milling time is 3h; the drying temperature is 110°C, and the drying time is 8h. The pretreatment process parameters of the spherical powder in the alumina of each particle size are: the immersion time is 1h; the first ball milling treatment, the ball milling speed is 180r / min, the ball milling time is 3h; the drying temperature is 110°C, and the drying time is 8h.

[0142] In step 3, the pretreatment process parameters of the quartz glass powder of each particle size are: the ball milling speed is 320 r / min, the ball milling time is 8 h, the drying temperature is 110° C., and the drying time is 8 h.

[0143] In step 4, the pretreatment process parameters of aluminum oxide of each particle size are as follows: the ball milling speed is 320 r / min, the ball milling time is 8 h, the drying temperature is 110° C., and the drying time is 8 h.

[0144] In step 5, the mixing speed of the pretreated quartz glass powder of various particle sizes, the pretreated alumina of various particle sizes, the mullite of various particle sizes, the zirconium silicate of various particle sizes, the titanium dioxide, and the pore-forming material is 20 r / min and the mixing time is 10 h.

[0145] In step six, the stirring temperature of the adhesive, plasticizer and surfactant is 60° C., the stirring speed is 200 r / min and the stirring time is 1 h.

[0146] In step seven, the stirring temperature of the ceramic powder and the plasticizer is 60° C., the stirring speed is 500 r / min, and the stirring time is 20 h.

[0147] In step eight, the pressing parameters of the silicon-based ceramic core blank are injection temperature 60° C., injection speed 120 cc / s, injection pressure 6 MPa, and holding time 40 s.

[0148] In step ten, the sintering parameters of the silicon-based ceramic core blank are a final sintering temperature of 1150° C. and a sintering time of 59 h.

[0149] Embodiment three:

[0150] According to another preferred embodiment of the silicon-based ceramic core and its preparation method for controlling strength based on angular ratio of the present invention, its material ratio, preparation process, technical principle, beneficial effects, etc. are basically the same as those of the first embodiment, except that:

[0151] The mass percentages of each substance in the silicon-based ceramic core are: 90wt% ceramic powder, 10wt% plasticizer; the mass percentages of each substance in the ceramic powder are: 85wt% quartz glass powder, 13wt% mineralizer, 2wt% pore-forming material; the mass percentages of each substance in the mineralizer are: 40wt% mullite, 45wt% alumina, 14wt% zirconium silicate, 1wt% titanium dioxide.

[0152] The quartz glass powder includes four particle sizes, namely 35-62μm, 13-35μm, 3-13μm, and 0.05-3μm; the mass percentage of each particle size in the quartz glass powder is as follows: 35-62μm accounts for 60wt%, 13-35μm accounts for 13wt%, 3-13μm accounts for 22wt%, and 0.05-3μm accounts for 5wt%.

[0153] The mullite is composed of mullite chopped fibers and mullite particles, and the mullite chopped fibers and the mullite particles account for 21wt% and 79wt% of the mass percentage of the mullite respectively; the length of the mullite chopped fibers is 45μm and the diameter is 170nm; the mullite particles include four particle sizes, namely 50-70μm, 30-50μm, 15-30μm, and 3-15μm, and the mass percentage of each particle size in the mullite particles is 65wt% for particle size 50-70μm, 20wt% for particle size 30-50μm, 13wt% for particle size 15-30μm, and 2wt% for particle size 3-15μm.

[0154] The aluminum oxide includes four particle sizes, namely 42-65 μm, 18-42 μm, 3-18 μm, and 0.05-3 μm; the mass percentage of each particle size in the aluminum oxide is: 42-65 μm accounts for 60wt%, 18-42 μm accounts for 13wt%, 3-18 μm accounts for 22wt%, and 0.05-3 μm accounts for 5wt%.

[0155] The zirconium silicate includes three particle sizes, namely 45-58 μm, 38-45 μm, and 18-38 μm, and the mass percentage of each particle size in the zirconium silicate is 55wt% for particle size 45-58 μm, 25wt% for particle size 38-45 μm, and 20wt% for particle size 18-38 μm. The titanium dioxide includes a particle size of 13-18 μm. The pore-forming material is graphite.

[0156] The mass percentages of the substances in the plasticizer are 90wt% of the binder, 5wt% of the plasticizer, and 5wt% of the surfactant; the binder is ceresin; the plasticizer is cellulose; and the surfactant is oleic acid.

[0157] In this embodiment, the strength of the silicon-based ceramic core is regulated by adjusting the angular ball ratio of quartz glass powder of various particle sizes and the angular ball ratio of alumina of various particle sizes in the mineralizer, thereby forming a silicon-based ceramic core material system with nearly linearly adjustable strength.

[0158] (1) Adjust the angle ratio of quartz glass powder of different particle sizes, wherein the angle ratio of quartz glass powder with a particle size of 35-62 μm is 30-50:50-70, the angle ratio of quartz glass powder with a particle size of 13-35 μm is 80-90:10-20, the angle ratio of quartz glass powder with a particle size of 3-13 μm is 85-95:5-15, and the angle ratio of quartz glass powder with a particle size of 0.05-3 μm is 95-99:1-5.

[0159] (2) Adjust the angular ratio of alumina of different particle sizes in the mineralizer, wherein the angular ratio of alumina with a particle size of 42-65 μm is 15-50:50-85, the angular ratio of alumina with a particle size of 18-42 μm is 25-50:50-75, the angular ratio of alumina with a particle size of 3-18 μm is 50-75:25-50, and the angular ratio of alumina with a particle size of 0.05-3 μm is 85-99:1-15.

[0160] In step 2, the pretreatment process parameters of the spherical powder in the quartz glass powder of each particle size are: the immersion time is 3h; the first ball milling treatment, the ball milling speed is 220r / min, the ball milling time is 1h; the drying temperature is 130°C, and the drying time is 6h. The pretreatment process parameters of the spherical powder in the alumina of each particle size are: the immersion time is 3h; the first ball milling treatment, the ball milling speed is 220r / min, the ball milling time is 1h; the drying temperature is 130°C, and the drying time is 6h.

[0161] In step 3, the pretreatment process parameters of the quartz glass powder of each particle size are: the ball milling speed is 380 r / min, the ball milling time is 4 h, the drying temperature is 130° C., and the drying time is 6 h.

[0162] In step 4, the pretreatment process parameters of aluminum oxide of each particle size are as follows: the ball milling speed is 380 r / min, the ball milling time is 4 h, the drying temperature is 130° C., and the drying time is 6 h.

[0163] In step 5, the mixing speed of the pretreated quartz glass powder of various particle sizes, the pretreated alumina of various particle sizes, the mullite of various particle sizes, the zirconium silicate of various particle sizes, the titanium dioxide, and the pore-forming material is 50 r / min and the mixing time is 6 h.

[0164] In step six, the stirring temperature of the adhesive, plasticizer and surfactant is 200° C., the stirring speed is 100 r / min and the stirring time is 4 h.

[0165] In step seven, the stirring temperature of the ceramic powder and the plasticizer is 200° C., the stirring speed is 300 r / min, and the stirring time is 24 h.

[0166] In step eight, the pressing parameters of the silicon-based ceramic core blank are injection temperature 105° C., injection speed 100 cc / s, injection pressure 10 MPa, and holding time 10 s.

[0167] In step ten, the sintering parameters of the silicon-based ceramic core blank are a final sintering temperature of 1300° C. and a sintering time of 43 h.

[0168] The chemical reagents, powder materials, etc. used in the above examples were purchased from Aladdin Reagent Co., Ltd. and Sinopharm Chemical Reagent Co., Ltd.

[0169] Special note: The technical solution of the present invention involves many parameters, and the synergistic effects between the various parameters need to be comprehensively considered to obtain the beneficial effects and significant progress of the present invention. Moreover, the value ranges of the various parameters in the technical solution are obtained after a large number of experiments. For each parameter and the combination of each parameter, the inventor has recorded a large amount of experimental data. Due to space limitations, the specific experimental data will not be disclosed here.

[0170] It is not difficult for those skilled in the art to understand that the silicon-based ceramic core and its preparation method based on angular ratio strength control of the present invention include any combination of the invention content and specific implementation methods of the above-mentioned invention specification and the various parts shown in the drawings. Due to the limited space and to make the specification concise, the various schemes composed of these combinations are not described one by one. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A silicon-based ceramic core with strength controlled by angular ratio, characterized in that: The mass percentage of each substance in the silicon-based ceramic core is 75-90wt% of ceramic powder and 10-25wt% of plasticizer; the mass percentage of each substance in the ceramic powder is 67-85wt% of quartz glass powder, 13-32wt% of mineralizer, and 0.1-2wt% of pore-forming material; the strength of the silicon-based ceramic core is regulated by adjusting the angular ratio of quartz glass powder of each particle size and the angular ratio of alumina of each particle size in the mineralizer, so as to form a silicon-based ceramic core material system with nearly linear adjustable strength, that is, to form a series of silicon-based ceramic core formulas with strengths close to arithmetic arrangement, and the formed series of silicon-based ceramic core formulas correspond to a series of strengths, and this series of strengths is evenly distributed within a certain range; The quartz glass powder includes four particle sizes, namely 35μm≤particle size<62μm, 13μm≤particle size<35μm, 3μm≤particle size<13μm, 0.05μm≤particle size<3μm, and the mass percentage of each particle size in the quartz glass powder is 45-60wt% for 35μm≤particle size<62μm, 10-25wt% for 13μm≤particle size<35μm, 20-30wt% for 3μm≤particle size<13μm, and 1-5wt% for 0.05μm≤particle size<3μm; The mass percentage of each substance in the mineralizer is 30-40wt% of mullite, 40-58wt% of alumina, 5-15wt% of zirconium silicate, and 1-5wt% of titanium dioxide; the alumina includes four particle sizes, namely 42μm≤particle size<65μm, 18μm≤particle size<42μm, 3μm≤particle size<18μm, and 0.05μm≤particle size<3μm, and the mass percentage of each particle size in the alumina is 42μm≤particle size<65μm, accounting for 45-60wt%, 18μm≤particle size<42μm, accounting for 10-25wt%, 3μm≤particle size<18μm, accounting for 20-30wt%, and 0.05μm≤particle size<3μm, accounting for 1-5wt%; Adjust the angular ball ratio of the quartz glass powder of each particle size, wherein the angular ball ratio is the mass ratio of angular powder to spherical powder, wherein the angular ball ratio of quartz glass powder with a particle size of 35 μm ≤ <62 μm is 30-50:50-70, the angular ball ratio of quartz glass powder with a particle size of 13 μm ≤ <35 μm is 80-90:10-20, the angular ball ratio of quartz glass powder with a particle size of 3 μm ≤ <13 μm is 85-95:5-15, and the angular ball ratio of quartz glass powder with a particle size of 0.05 μm ≤ <3 μm is 95-99:1-5; The angular ball ratio of alumina of each particle size in the mineralizer is adjusted, and the angular ball ratio is the mass ratio of angular powder to spherical powder, wherein the angular ball ratio of alumina with a particle size of 42μm≤<65μm is 15-50:50-85, the angular ball ratio of alumina with a particle size of 18μm≤<42μm is 25-50:50-75, the angular ball ratio of alumina with a particle size of 3μm≤<18μm is 50-75:25-50, and the angular ball ratio of alumina with a particle size of 0.05μm≤<3μm is 85-99:1-15.

2. The silicon-based ceramic core with strength controlled by angular ratio according to claim 1, characterized in that: The mullite is composed of mullite chopped fibers and mullite particles, and the mass percentages of the mullite chopped fibers and the mullite particles are 7-21wt% and 79-93wt% respectively; the length of the mullite chopped fibers is 18-45μm and the diameter is 100-170nm; the mullite particles include four particle sizes, namely 50μm≤particle size<70μm, 30μm≤particle size<50μm, 15μm≤particle size<30μm, and 3μm≤particle size<15μm, and the mass percentage of each particle size in the mullite particles is 49-65wt% for 50μm≤particle size<70μm, 20-25wt% for 30μm≤particle size<50μm, 10-20wt% for 15μm≤particle size<30μm, and 1-7wt% for 3μm≤particle size<15μm.

3. The silicon-based ceramic core with strength controlled by angular ratio according to claim 2, characterized in that: The zirconium silicate includes three particle sizes, namely 45μm≤particle size<58μm, 38μm≤particle size<45μm, and 18μm≤particle size<38μm. The mass percentage of each particle size in the zirconium silicate is: 45μm≤particle size<58μm accounts for 40-55wt%, 38μm≤particle size<45μm accounts for 25-35wt%, and 18μm≤particle size<38μm accounts for 20-25wt%.

4. The silicon-based ceramic core with strength controlled by angular ratio according to claim 3, characterized in that: The titanium dioxide has a particle size range of 13-18 μm.

5. The silicon-based ceramic core with strength controlled by angular ratio according to claim 4, characterized in that: The pore-forming material includes any one or more of graphite, graphene, starch, and carbon nanotubes.

6. The silicon-based ceramic core with strength controlled by angular ratio according to claim 5, characterized in that: The mass percentages of the various substances in the plasticizer are as follows: 80-90wt% of the adhesive, 3-10wt% of the plasticizer, and 2-10wt% of the surfactant; the adhesive includes any one or more of paraffin, beeswax, and ozokerite; the plasticizer is low-density polyethylene and / or cellulose; the surfactant includes any one or more of stearic acid, oleic acid, sodium stearate, and aluminum stearate.

7. A method for preparing a silicon-based ceramic core with strength controlled by angular ratio, characterized in that: The method for preparing the silicon-based ceramic core with angular ratio-controlled strength as claimed in claim 6 comprises the following steps in chronological order: Step 1: Weigh all raw materials according to the designed material ratio; Step 2: pre-treating the spherical powder in the quartz glass powder of each particle size respectively, and pre-treating the spherical powder in the alumina powder of each particle size respectively; Step 3: according to the designed angular-spherical ratio of the quartz glass powder of each particle size, the angular powder in each particle size and the pretreated spherical powder are mixed evenly to obtain quartz glass powder of each particle size, and then the quartz glass powder of each particle size is pretreated; Step 4: according to the designed angular-spherical ratio of aluminum oxide of each particle size, the angular powder in each particle size and the pretreated spherical powder are mixed evenly to obtain aluminum oxide of each particle size, and then the aluminum oxide of each particle size is pretreated; Step 5: Put the pretreated quartz glass powder of various particle sizes, the pretreated alumina of various particle sizes, the mullite of various particle sizes, the zirconium silicate of various particle sizes, the titanium dioxide, and the pore-forming material into a V-type mixer and mix them evenly to obtain ceramic powder; Step 6: According to the designed material ratio, the three components of the plasticizer, namely, the adhesive, the plasticizer, and the surfactant, are placed in a blender for heating and stirring, so that the adhesive, the plasticizer, and the surfactant are completely blended to obtain the plasticizer; Step 7: Put the ceramic powder and the plasticizer into a mixer according to the designed material ratio, heat and stir them, so that the ceramic powder and the plasticizer are evenly mixed to obtain a silicon-based ceramic core slurry; Step 8: manufacturing a ceramic core mold according to the designed ceramic core structure, injecting the silicon-based ceramic core slurry into the ceramic core mold by using an injection molding machine for filling and pressing to obtain a silicon-based ceramic core blank; Step 9: Check the silicon-based ceramic core blank and confirm that there are no obvious defects in its appearance, then insert the silicon-based ceramic core blank into a calcined pot filled with kaolin filler, and make the kaolin filler completely cover the silicon-based ceramic core blank; Step 10: Place the calcining pot containing the kaolin filler and the silicon-based ceramic core blank into a calcining furnace for calcining. After the calcining is completed, a silicon-based ceramic core with strength regulated based on the angle ratio can be obtained.

8. The method for preparing a silicon-based ceramic core with strength controlled by angular ratio according to claim 7, characterized in that: In step 2, the pretreatment of spherical powder in quartz glass powder of each particle size includes the following steps in order: Step (2-1): immersing the spherical powders in the quartz glass powders of different particle sizes in the silica sol respectively, the immersion temperature is all at room temperature, the immersion time is all 1-3 hours, and after the immersion is completed, the spherical powders are filtered out; Step (2-2): putting the spherical powders in the quartz glass powders of each particle size into a ball mill respectively, adding deionized water and zirconium oxide ball milling beads into the ball mill, the mass ratio of the spherical powder to the deionized water is 1:3, the mass ratio of the spherical powder to the zirconium oxide ball milling beads is 1:1, the diameter of the zirconium oxide ball milling beads is 3 mm, and then putting the ball mill into a planetary ball mill for the first ball milling, the ball milling speed is 180-220 r / min, and the ball milling time is 1-3 h; Step (2-3): After the first ball milling is completed, the spherical powder, deionized water and zirconium oxide ball milling beads are taken out from the ball milling jar and separated, and then the operation of step (2-2) is repeated to perform the second ball milling; Step (2-4): After the second ball milling is completed, the spherical powder is taken out from the ball mill, and then placed in a blast drying oven for drying, the drying temperature is 110-130°C, and the drying time is 6-8h; In step 2, the pretreatment of the spherical powder in each particle size alumina comprises the following steps in order: Step (2-a): immersing the spherical powders of alumina of different particle sizes in silica sol respectively, at room temperature for 1-3 hours, and filtering out the spherical powders after the immersion is completed; Step (2-b): putting the spherical powders of alumina of different particle sizes into ball mills respectively, adding deionized water and zirconium oxide ball milling beads into the ball mills, wherein the mass ratio of the spherical powder to the deionized water is 1:3, the mass ratio of the spherical powder to the zirconium oxide ball milling beads is 1:1, and the diameter of the zirconium oxide ball milling beads is 3 mm, and then putting the ball mills into a planetary ball mill for the first ball milling, wherein the ball milling speed is 180-220 r / min, and the ball milling time is 1-3 h; Step (2-c): After the first ball milling is completed, the spherical powder, deionized water and zirconium oxide ball milling beads are taken out from the ball milling jar and separated, and then the operation of step (2-b) is repeated to perform the second ball milling; Step (2-d): After the second ball milling is completed, the spherical powder is taken out from the ball mill, and then placed in a blast drying oven for drying. The drying temperature is 110-130° C. and the drying time is 6-8 h.

9. The method for preparing a silicon-based ceramic core with strength controlled by angular ratio according to claim 8, characterized in that: In step 3, the pretreatment of the quartz glass powder of each particle size includes the following steps in order: Step (3-1): placing quartz glass powders of various particle sizes into ball mills respectively, adding deionized water and zirconium oxide ball milling beads into the ball mills, wherein the mass ratio of quartz glass powder to deionized water is 1:1, the mass ratio of quartz glass powder to zirconium oxide ball milling beads is 1:1, and the diameter of the zirconium oxide ball milling beads is 3 mm, and then placing the ball mills into a planetary ball mill for ball milling, the ball milling speed is 320-380 r / min, and the ball milling time is 4-8 h; Step (3-2): After the ball milling is completed, the quartz glass powder is taken out from the ball mill jar and then placed in a blast drying oven for drying. The drying temperature is 110-130°C and the drying time is 6-8h. In step 4, the pretreatment of aluminum oxide of each particle size comprises the following steps in order: Step (4-1): placing aluminum oxide of various particle sizes into a ball mill respectively, adding deionized water and zirconium oxide ball milling beads into the ball mill, wherein the mass ratio of aluminum oxide to deionized water is 1:1, the mass ratio of aluminum oxide to zirconium oxide ball milling beads is 1:1, and the diameter of the zirconium oxide ball milling beads is 3 mm, and then placing the ball mill into a planetary ball mill for ball milling, the ball milling speed is 320-380 r / min, and the ball milling time is 4-8 h; Step (4-2): After the ball milling is completed, the alumina is taken out from the ball mill jar and then placed in a blast drying oven for drying. The drying temperature is 110-130°C and the drying time is 6-8h.

10. The method for preparing a silicon-based ceramic core with strength controlled by angular ratio according to claim 9, characterized in that: In step 5, the mixing speed of the pretreated quartz glass powder of each particle size, the pretreated alumina of each particle size, the mullite of each particle size, the zirconium silicate of each particle size, the titanium dioxide, and the pore-forming material is 20-50 r / min and the mixing time is 6-10 h; In step 6, the stirring temperature of the adhesive, plasticizer and surfactant is 60-200°C, the stirring speed is 100-200r / min, and the stirring time is 1-4h; In step 7, the stirring temperature of the ceramic powder and the plasticizer is 60-200° C., the stirring speed is 300-500 r / min, and the stirring time is 20-24 h; In step eight, the pressing parameters of the silicon-based ceramic core blank are injection temperature 60-105° C., injection speed 100-120 cc / s, injection pressure 6-10 MPa, and holding time 10-40 s. In step ten, the sintering parameters of the silicon-based ceramic core blank are a final sintering temperature of 1150-1300° C. and a sintering time of 43-59 h.

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