Ceramic shell phase detection method suitable for precision casting

Abstract

The invention discloses a ceramic shell phase detection method suitable for precision casting, which comprises the following steps: preparing ceramic slurry, and carrying out pre-dispersion treatment on the ceramic slurry; taking out part of the ceramic slurry, putting the ceramic slurry into a cylindrical transparent container, and coating an opening with a sealing film; performing liquid nitrogen quenching on the ceramic slurry for three times to obtain a solid ceramic slurry block; punching a part of holes in the sealing film, and carrying out vacuum freeze drying on the ceramic slurry block, so that solid water in the ceramic slurry block is sublimated into gas and escapes; repeating the steps of three times of liquid nitrogen quenching and one time of vacuum freeze drying; and roasting the ceramic slurry block, cutting the ceramic slurry block, and detecting the flat surface of the sample by adopting an X-ray diffraction method. According to the invention, phase detection is carried out on the ceramic slurry instead of directly carrying out phase detection on the ceramic shell, so that the authenticity and the accuracy of phase detection are improved, and the uniformity of a sample is ensured when the ceramic slurry sample is used for detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of material property testing and sample preparation, and particularly relates to a method for detecting the phase of a ceramic shell suitable for precision casting, especially for detecting the phase of a ceramic shell used in the investment casting process of a superalloy turbine blade. Background Art

[0002] An aeroengine is the heart of an aircraft. Its internal structure is very complex and consists of hundreds of thousands of components. Therefore, it is known as the pearl on the industrial crown. With the continuous progress of modern technology, aeroengines are required to have more powerful power to meet the needs of various industries such as military and civilian. The power of an aeroengine mainly depends on the temperature at the inlet of its turbine. The higher the temperature, the stronger the power of the aeroengine. The turbine blade is the component with the highest temperature-bearing requirement in the entire aeroengine, and its service environment is very harsh. The temperature-bearing capacity of the turbine blade directly determines the temperature at the inlet of the turbine, thereby affecting the power limit of the aeroengine. This is also the reason why the turbine blade is the most important core component in the entire aeroengine.

[0003] Currently, the main method for manufacturing turbine blades is precision casting, which requires multiple processes such as wax pattern preparation, shell preparation, melting and pouring. Among them, as the pouring carrier of a superalloy turbine blade, the ceramic shell is formed by evenly coating a ceramic slurry on the surface of a wax pattern, and then using refractory sand for sand spraying. After it is fully dried, the processes of coating the slurry, sand spraying, and drying are repeated, so that a hierarchically stacked ceramic shell composed of refractory slurry and refractory sand can be obtained.

[0004] The ceramic shell used for manufacturing superalloy turbine blades mainly consists of refractory slurries such as corundum, silica, and mullite. After being calcined at a high temperature above 1400 °C, phase transformation processes such as cristobalite transformation and secondary mullite phase formation often occur inside them. This kind of phase transformation will cause changes in the properties such as the size and strength of the ceramic shell, resulting in problems such as dimensional tolerance exceeding and pouring leakage in turbine blade castings. Therefore, it is particularly important to clarify the phase changes of the ceramic shell at high temperatures.

[0005] Currently, the phase detection of ceramic shells mainly uses the X-ray diffraction method (XRD). This method is based on the diffraction effect of X-rays on crystals and realizes the determination of the material structure by analyzing the atomic spatial arrangement structure inside the material. When X-rays with a certain wavelength are irradiated on a crystalline substance, the X-rays are scattered because they encounter regularly arranged atoms or ions in the crystal, and the scattered X-rays are strengthened in phase in certain directions, thus showing a unique diffraction phenomenon corresponding to the crystal structure.

[0006] When performing XRD phase detection on a ceramic shell mold, since the size of the refractory sand is dozens or even hundreds of times that of the refractory powder and nano-silica in the refractory slurry, X-rays often irradiate on the refractory sand, while the phase transformation often occurs between the refractory powder and nano-silica, which will cause the phase detection results to be distorted. If directly using the ceramic slurry for phase detection, it often faces the problem that the ceramic slurry has a too long standing time resulting in the layering of the ceramic slurry, that is, the layering of silica sol and refractory powder. Therefore, there is an urgent need to develop a phase detection method suitable for the ceramic shell mold used in the investment casting process of superalloy turbine blades, so as to effectively and accurately measure the phase transformation of the ceramic shell mold at high temperature. Summary of the Invention

[0007] To solve the problems existing in the prior art, the present invention provides a phase detection method for a ceramic shell mold suitable for precision casting. By performing phase detection on the ceramic slurry to replace directly performing phase detection on the ceramic shell mold, the detection method includes the following steps in sequence:

[0008] Step 1: Prepare a ceramic slurry for preparing a ceramic shell mold according to the designed material ratio;

[0009] Step 2: Take out a part of the prepared ceramic slurry and put it into a mixing container, and then put the mixing container filled with the ceramic slurry into a biaxial rotary mixing device to perform pre-dispersion treatment on the ceramic slurry;

[0010] Step 3: Take out a part of the ceramic slurry after pre-dispersion treatment and put it into a cylindrical transparent container, and then use a sealing film to cover and seal the opening of the cylindrical transparent container. At this time, the ceramic slurry is in a flowing state;

[0011] Step 4: Use a clamping tool to vertically put the covered and sealed cylindrical transparent container into a liquid nitrogen bucket, and make the cylindrical transparent container completely immersed in the liquid nitrogen to perform the first liquid nitrogen rapid cooling on the ceramic slurry; after the first liquid nitrogen rapid cooling is completed, use the clamping tool to vertically take out the cylindrical transparent container and place it on the horizontal ground to let the ceramic slurry stand;

[0012] Step 5: Use a clamping tool to vertically put the cylindrical transparent container into the liquid nitrogen bucket again, and make the cylindrical transparent container completely immersed in the liquid nitrogen to perform the second liquid nitrogen rapid cooling on the ceramic slurry; after the second liquid nitrogen rapid cooling is completed, use the clamping tool to vertically take out the cylindrical transparent container and place it on the horizontal ground to let the ceramic slurry stand;

[0013] Step 6: Use the clamping tool to vertically place the cylindrical transparent container into the liquid nitrogen bucket again, and fully immerse the cylindrical transparent container in the liquid nitrogen for the third rapid cooling of the ceramic slurry. After the third rapid cooling with liquid nitrogen is completed, use the clamping tool to take out the cylindrical transparent container. At this time, the ceramic slurry is completely frozen and formed into a ceramic slurry block, and the ceramic slurry changes from the initial flowing state to a solid state.

[0014] Step 7: Uniformly punch out some holes in the sealing film at the opening of the cylindrical transparent container, and then place the cylindrical transparent container in a freeze dryer for vacuum freeze-drying of the ceramic slurry block, so that the solid moisture inside the ceramic slurry block sublimes into gas and escapes.

[0015] Step 8: Repeat the operations in Step 4 to Step 7. After repeating one to two times, the solid moisture in the ceramic slurry block can be completely removed, and then take out the ceramic slurry block from the cylindrical transparent container. The ceramic slurry block is cylindrical.

[0016] Step 9: Place the cylindrical ceramic slurry block in a roasting furnace for roasting treatment.

[0017] Step 10: After the roasting treatment is completed, use wire cutting to cut a cuboid sample from the central part of the cylindrical ceramic slurry block, and evenly divide the cuboid sample into two parts in the height direction. Take the interface as the detection plane for the phase detection of the ceramic slurry block.

[0018] Step 11: Use X-ray diffraction to perform phase detection on the detection plane.

[0019] Preferably, in Step 1, the ceramic slurry is composed of fused white corundum powder, silica sol, cyanite, defoamer, and wetting agent. The mass ratio of the fused white corundum powder to the silica sol is 3.5 - 4:1. The addition amount of cyanite is 2 - 3% of the mass of the fused white corundum powder. The addition amount of the defoamer is 3 - 5% of the mass of the silica sol. The addition amount of the wetting agent is 3 - 5% of the mass of the silica sol.

[0020] The median particle size of the fused white corundum powder is 20 - 30 μm; the SiO2 content in the silica sol is 20 - 30 wt%; the mass percentages of each substance in the defoamer are: organosilane defoamer 45 - 55 wt%, n-octanol 45 - 55 wt%; the wetting agent is a gemini-based silicone wetting agent.

[0021] The preparation method of the ceramic slurry is as follows: First, mix the organosilane defoamer and n-octanol evenly at room temperature to obtain the defoamer; then put the silica sol, defoamer, and wetting agent into a reaction kettle and stir. The stirring temperature is 20 - 25°C, and the stirring time is 10 - 30 min to make the three substances fully blend; finally, put kyanite and fused white corundum powder into the reaction kettle and continue stirring. The stirring temperature is 20 - 25°C, and the stirring time is 1 - 5 h to obtain the ceramic slurry; the outflow cup viscosity of the ceramic slurry is 10 - 30 s.

[0022] In any of the above - mentioned schemes, preferably, in step two, the mass of the ceramic slurry put into the mixing container is 500 - 700 g, the temperature of the pre - dispersion treatment is room temperature, the speed is 400 - 500 r / min, and the time is 12 - 15 h.

[0023] In any of the above - mentioned schemes, preferably, in step three, the inner cavity diameter of the cylindrical transparent container is 5 cm. Put the ceramic slurry into the cylindrical transparent container, and the height of the ceramic slurry is 3 - 4 cm.

[0024] In any of the above - mentioned schemes, preferably, in step four, the time for the first liquid nitrogen rapid cooling of the ceramic slurry is 20 - 30 s, and the standing time after taking out the ceramic slurry is 3 - 5 s.

[0025] In any of the above - mentioned schemes, preferably, in step five, the time for the second liquid nitrogen rapid cooling of the ceramic slurry is 10 - 15 s, and the standing time after taking out the ceramic slurry is 3 - 5 s.

[0026] In any of the above - mentioned schemes, preferably, in step six, the time for the third liquid nitrogen rapid cooling of the ceramic slurry is 10 - 15 s.

[0027] In any of the above - mentioned schemes, preferably, in step seven, the ceramic slurry block is subjected to vacuum freeze - drying. The temperature is - 50~ - 10°C, the vacuum degree is 1.3 - 13 Pa, and the time is 12 - 15 h.

[0028] In any of the above - mentioned schemes, preferably, in step nine, the roasting treatment process of the cylindrical ceramic slurry block is as follows: First, put the cylindrical ceramic slurry block into a roasting furnace and raise the temperature from room temperature to 900°C at a speed of 15 - 20°C / min; then raise the temperature from 900°C to 1400 - 1500°C at a speed of 5 - 10°C / min and keep it warm for 30 - 40 min; finally, lower the temperature from 1400 - 1500°C to room temperature at a speed of 15 - 20°C / min, and the cylindrical ceramic slurry block cools with the furnace.

[0029] In any of the above - mentioned schemes, preferably, in step ten, the length of the cuboid - shaped sample is 1 cm, the width is 1 cm, and the height is 2 - 3 cm.

[0030] In the present invention, liquid nitrogen is used to rapidly cool the ceramic slurry, freezing the water in the ceramic slurry in the fastest way, so that the powder particles and nano-silica in the ceramic slurry block remain in a uniformly dispersed state.

[0031] The ceramic slurry block is subjected to vacuum freeze-drying, mainly to sublime the solid water inside the ceramic slurry block. By controlling the temperature, vacuum degree and time, and using the principle of ice crystal sublimation, the solid water inside the ceramic slurry block directly sublimes into gas and escapes without passing through the liquid state.

[0032] Before the ceramic slurry block is subjected to vacuum freeze-drying, some holes need to be evenly punched in the sealing film, which can make the cylindrical transparent container reach a vacuum state and also allow the water inside the ceramic slurry block to escape after sublimation.

[0033] Taking the three-time rapid cooling of the ceramic slurry with liquid nitrogen and the one-time vacuum freeze-drying of the ceramic slurry block as a cycle period, it is necessary to repeat the operation one to two times, which can fully freeze the water in the ceramic slurry and completely remove the solid water in the ceramic slurry block, so that the powder particles and nano-silica in the ceramic slurry block remain in a more uniformly dispersed state.

[0034] In the present invention, within one cycle period, the ceramic slurry needs to undergo three-time rapid cooling with liquid nitrogen, the ceramic slurry block needs to undergo one-time vacuum freeze-drying, and it is necessary to repeat the operation one to two times. The process parameters of the three-time rapid cooling with liquid nitrogen and the vacuum freeze-drying are very important. At the same time, the process parameters of the roasting treatment of the ceramic slurry block are also very important. Each parameter needs to work together to achieve the technical effects expected by the present invention. The double-axis rotation mixing equipment, roasting furnace, freeze-dryer, vacuum pump, wire cutting machine, etc. used in the present invention are all traditional equipment, and there are no special requirements for the equipment structure and model.

[0035] The present invention is applicable to the method for detecting the phase of the ceramic shell for precision casting, and has the following beneficial effects:

[0036] (1) In the present invention, the phase detection of the ceramic slurry is used to replace the direct phase detection of the ceramic shell, and it is not necessary to directly use the ceramic shell for X-ray diffraction detection, avoiding the problem of large detection errors caused by the too large volume of refractory sand in the ceramic shell.

[0037] (2) When the ceramic slurry block is used for phase detection in the present invention, due to the processes of multiple rapid cooling with liquid nitrogen and vacuum freeze-drying treatment, the nano-silica inside the ceramic slurry block can be uniformly fused with the powder, avoiding the layering of powder particles and silica sol nano-silica caused by precipitation during traditional sampling, ensuring the uniformity of the detection sample, and improving the authenticity and accuracy of phase detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 FIG. is a flowchart of a preferred embodiment of the method for detecting the phase of a ceramic mold shell suitable for precision casting according to the present invention;

[0039] Figure 2 is Figure 1 a microstructural photograph of the detection plane of the ceramic slurry block of the illustrated embodiment;

[0040] Figure 3 is Figure 1 the X-ray diffraction result of the detection plane of the ceramic slurry block of the illustrated embodiment;

[0041] Figure 4 a microstructural photograph of the detection plane of the ceramic slurry block of Comparative Example 1;

[0042] Figure 5 the X-ray diffraction result of the detection plane of the ceramic slurry block of Comparative Example 1;

[0043] Figure 6 a microstructural photograph of the detection plane of the ceramic mold shell of Comparative Example 2;

[0044] Figure 7 the X-ray diffraction result of the detection plane of the ceramic mold shell of Comparative Example 2. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] In order to further understand the content of the present invention, the present invention will be described in detail below with reference to specific embodiments.

[0046] Example 1:

[0047] As Figure 1 shown, in a preferred embodiment of the method for detecting the phase of a ceramic mold shell suitable for precision casting according to the present invention, the phase detection of the ceramic mold shell is replaced by the phase detection of the ceramic slurry, and the detection method includes the following steps in sequence:

[0048] Step 1: Prepare the ceramic slurry for preparing the ceramic mold shell according to the designed material ratio;

[0049] Step 2: Take out a part of the prepared ceramic slurry and put it into a mixing container. Then, place the mixing container containing the ceramic slurry into a double-axis rotary mixing device to perform pre-dispersion treatment on the ceramic slurry;

[0050] Step 3: Take out a part of the ceramic slurry after pre-dispersion treatment and put it into a cylindrical transparent container. Then, use a sealing film to cover and seal the opening of the cylindrical transparent container. At this time, the ceramic slurry is in a flowing state;

[0051] Step 4: Use a clamping tool to vertically place the covered and sealed cylindrical transparent container into a liquid nitrogen tank and immerse the cylindrical transparent container completely in the liquid nitrogen to perform the first rapid liquid nitrogen cooling on the ceramic slurry; after the first rapid liquid nitrogen cooling ends, use the clamping tool to vertically take out the cylindrical transparent container and place it on a horizontal ground to let the ceramic slurry stand;

[0052] Step 5: Use a clamping tool to vertically place the cylindrical transparent container into the liquid nitrogen tank again and immerse the cylindrical transparent container completely in the liquid nitrogen to perform the second rapid liquid nitrogen cooling on the ceramic slurry; after the second rapid liquid nitrogen cooling ends, use the clamping tool to vertically take out the cylindrical transparent container and place it on a horizontal ground to let the ceramic slurry stand;

[0053] Step 6: Use a clamping tool to vertically place the cylindrical transparent container into the liquid nitrogen tank again and immerse the cylindrical transparent container completely in the liquid nitrogen to perform the third rapid liquid nitrogen cooling on the ceramic slurry; after the third rapid liquid nitrogen cooling ends, use the clamping tool to take out the cylindrical transparent container. At this time, the ceramic slurry is completely frozen and formed into a ceramic slurry block, and the ceramic slurry changes from the initial flowing state to a solid state;

[0054] Step 7: Uniformly punch out some holes in the sealing film at the opening of the cylindrical transparent container, and then put the cylindrical transparent container into a freeze dryer to perform vacuum freeze-drying on the ceramic slurry block, so that the solid moisture inside the ceramic slurry block sublimes into a gaseous state and escapes;

[0055] Step 8: Repeat the operations in Step 4 to Step 7 twice. After that, the solid moisture in the ceramic slurry block can be completely removed. Then, take out the ceramic slurry block from the cylindrical transparent container. The ceramic slurry block is cylindrical;

[0056] Step 9: Put the cylindrical ceramic slurry block into a roasting furnace for roasting treatment;

[0057] Step 10: After the roasting treatment ends, cut out a cuboid sample from the central part of the cylindrical ceramic slurry block by wire cutting, and evenly divide the cuboid sample into two parts in the height direction. Use the interface as the detection plane for the phase detection of the ceramic slurry block;

[0058] Step Eleven: Perform phase detection on the detection plane by means of X-ray diffraction.

[0059] In Step One, the ceramic slurry is composed of fused white corundum powder, silica sol, cyanite, defoamer, and wetting agent. The mass ratio of the fused white corundum powder to the silica sol is 3.8:1. The addition amount of the cyanite is 2.5% of the mass of the fused white corundum powder. The addition amount of the defoamer is 4% of the mass of the silica sol. The addition amount of the wetting agent is 4% of the mass of the silica sol.

[0060] The median particle size of the fused white corundum powder is 25 μm; the SiO2 content in the silica sol is 25 wt%; the mass percentages of various substances in the defoamer are 50 wt% of organosilane defoamer and 50 wt% of n-octanol; the wetting agent is a gemini-based siloxane wetting agent.

[0061] The preparation method of the ceramic slurry is as follows: First, mix the organosilane defoamer and n-octanol evenly at room temperature to obtain the defoamer; then put the silica sol, defoamer, and wetting agent into a reaction kettle and stir. The stirring temperature is 22 °C and the stirring time is 20 min to make the three substances fully blend; finally, put the cyanite and fused white corundum powder into the reaction kettle and continue to stir. The stirring temperature is 22 °C and the stirring time is 3 h to obtain the ceramic slurry; the outflow cup viscosity of the ceramic slurry is 20 s.

[0062] In Step Two, the mass of the ceramic slurry put into the mixing container is 600 g, and the temperature, speed, and time of the pre-dispersion treatment are room temperature, 450 r / min, and 13 h respectively.

[0063] In Step Three, the inner cavity diameter of the cylindrical transparent container is 5 cm. Put the ceramic slurry into the cylindrical transparent container, and the height of the ceramic slurry is 3.5 cm.

[0064] In Step Four, the time for the first rapid cooling of the ceramic slurry with liquid nitrogen is 25 s, and the standing time after taking out the ceramic slurry is 4 s.

[0065] In Step Five, the time for the second rapid cooling of the ceramic slurry with liquid nitrogen is 12 s, and the standing time after taking out the ceramic slurry is 4 s.

[0066] In Step Six, the time for the third rapid cooling of the ceramic slurry with liquid nitrogen is 12 s.

[0067] In Step Seven, the ceramic slurry block is subjected to vacuum freeze-drying at a temperature of -30 °C, a vacuum degree of 7 Pa, and a time of 13 h.

[0068] In Step 9, the baking process of the cylindrical ceramic slurry block is as follows: First, place the cylindrical ceramic slurry block in a baking furnace and heat it from room temperature to 900°C at a rate of 18°C / min; then heat it from 900°C to 1450°C at a rate of 8°C / min and hold for 35 min; finally, cool it from 1450°C to room temperature at a rate of 18°C / min, and the cylindrical ceramic slurry block cools with the furnace.

[0069] In Step 10, the cuboid sample has a length of 1 cm, a width of 1 cm, and a height of 2.5 cm.

[0070] In this embodiment, within one cycle, the ceramic slurry needs to be quenched by liquid nitrogen three times, the ceramic slurry block needs to be vacuum freeze-dried once, and the operation needs to be repeated twice. The process parameters of the three liquid nitrogen quenches and the vacuum freeze-drying are very important. At the same time, the baking process parameters of the ceramic slurry block are also very important. All parameters need to work together to achieve the expected technical effects of this embodiment. The double-axis rotation mixing equipment, baking furnace, freeze dryer, vacuum pump, wire cutting machine, etc. used in this embodiment are all traditional equipment, and there are no special requirements for the equipment structure and model.

[0071] This embodiment is applicable to the method for detecting the phase of a ceramic shell for precision casting, and has the following beneficial effects: (1) By detecting the phase of the ceramic slurry instead of directly detecting the phase of the ceramic shell, it is not necessary to directly use the ceramic shell for X-ray diffraction detection, avoiding the problem of large detection errors caused by the large volume of refractory sand in the ceramic shell. (2) When using the ceramic slurry block for phase detection, due to the processes of multiple liquid nitrogen quenches and vacuum freeze-drying, the uniform fusion between the nano-silica and powder particles inside the ceramic slurry block can be achieved, avoiding the layering of powder particles and silica sol nano-silica due to precipitation during traditional sampling, ensuring the uniformity of the detection sample, and improving the authenticity and accuracy of the phase detection.

[0072] Embodiment 2:

[0073] According to another preferred embodiment of the method for detecting the phase of a ceramic shell for precision casting according to the present invention, its process flow, material ratio, technical principle, beneficial effects, etc. are basically the same as those of Embodiment 1, except that:

[0074] In Step 1, the ceramic slurry is composed of fused white corundum powder, silica sol, cyanite, defoaming agent, and wetting agent. The mass ratio of the fused white corundum powder to the silica sol is 3.5:1. The addition amount of the cyanite is 2% of the mass of the fused white corundum powder. The addition amount of the defoaming agent is 3% of the mass of the silica sol. The addition amount of the wetting agent is 3% of the mass of the silica sol.

[0075] The median particle size of the fused white corundum powder is 20 μm; the SiO2 content in the silica sol is 20 wt%; the mass percentages of the substances in the defoamer are 45 wt% of the organosilane defoamer and 55 wt% of n-octanol; the wetting agent is a gemini-based silicone wetting agent.

[0076] The preparation method of the ceramic slurry is as follows: First, mix the organosilane defoamer and n-octanol evenly at room temperature to obtain the defoamer; then put the silica sol, defoamer, and wetting agent into a reaction kettle and stir. The stirring temperature is 20 °C and the stirring time is 30 min to completely blend the three substances; finally, put the kyanite and fused white corundum powder into the reaction kettle and continue to stir. The stirring temperature is 20 °C and the stirring time is 5 h to obtain the ceramic slurry; the flow cup viscosity of the ceramic slurry is 10 s.

[0077] In step two, the mass of the ceramic slurry put into the mixing container is 500 g, and the temperature, speed, and time of the pre-dispersion treatment are room temperature, 400 r / min, and 15 h respectively.

[0078] In step three, the inner cavity diameter of the cylindrical transparent container is 5 cm. Put the ceramic slurry into the cylindrical transparent container, and the height of the ceramic slurry is 3 cm.

[0079] In step four, the time for the first rapid cooling of the ceramic slurry with liquid nitrogen is 20 s, and the standing time after taking out the ceramic slurry is 3 s.

[0080] In step five, the time for the second rapid cooling of the ceramic slurry with liquid nitrogen is 10 s, and the standing time after taking out the ceramic slurry is 3 s.

[0081] In step six, the time for the third rapid cooling of the ceramic slurry with liquid nitrogen is 10 s.

[0082] In step seven, the ceramic slurry block is subjected to vacuum freeze-drying at a temperature of -50 °C, a vacuum degree of 1.3 Pa, and a time of 12 h.

[0083] In step eight, repeat the operations of step four to step seven once.

[0084] In step nine, the roasting treatment process of the cylindrical ceramic slurry block is as follows: First, put the cylindrical ceramic slurry block into a roasting furnace and raise the temperature from room temperature to 900 °C at a rate of 20 °C / min; then raise the temperature from 900 °C to 1400 °C at a rate of 10 °C / min and hold for 30 min; finally, lower the temperature from 1400 °C to room temperature at a rate of 20 °C / min, and the cylindrical ceramic slurry block cools with the furnace.

[0085] In step ten, the length, width, and height of the cuboid sample are 1 cm, 1 cm, and 2 cm respectively.

[0086] Example 3:

[0087] According to another preferred embodiment of the ceramic shell phase detection method applicable to precision casting of the present invention, its process flow, material ratio, technical principle, beneficial effects, etc. are basically the same as those of Example 1, except that:

[0088] In Step 1, the ceramic slurry is composed of fused white corundum powder, silica sol, cyanite, defoaming agent and wetting agent. The mass ratio of the fused white corundum powder to the silica sol is 4:1. The addition amount of the cyanite is 3% of the mass of the fused white corundum powder. The addition amount of the defoaming agent is 5% of the mass of the silica sol. The addition amount of the wetting agent is 5% of the mass of the silica sol.

[0089] The median particle size of the fused white corundum powder is 30μm; the SiO2 content in the silica sol is 30wt%; the mass percentages of each substance in the defoaming agent are: organosilane defoaming agent 55wt%, n-octanol 45wt%; the wetting agent is a gemini-based siloxane wetting agent.

[0090] The preparation method of the ceramic slurry is as follows: First, mix the organosilane defoaming agent and n-octanol evenly at room temperature to obtain the defoaming agent; then put the silica sol, defoaming agent and wetting agent into a reaction kettle and stir. The stirring temperature is 25°C and the stirring time is 10min to make the three substances fully blend; finally, put the cyanite and fused white corundum powder into the reaction kettle and continue to stir. The stirring temperature is 25°C and the stirring time is 1h to obtain the ceramic slurry; the outflow cup viscosity of the ceramic slurry is 30s.

[0091] In Step 2, the mass of the ceramic slurry put into the mixing container is 700g, and the temperature of the pre-dispersion treatment is room temperature, the speed is 500r / min, and the time is 12h.

[0092] In Step 3, the inner cavity diameter of the cylindrical transparent container is 5cm, and the ceramic slurry is put into the cylindrical transparent container, and the height of the ceramic slurry is 4cm.

[0093] In Step 4, the time for the first rapid cooling of the ceramic slurry with liquid nitrogen is 30s, and the standing time after taking out the ceramic slurry is 5s.

[0094] In Step 5, the time for the second rapid cooling of the ceramic slurry with liquid nitrogen is 15s, and the standing time after taking out the ceramic slurry is 5s.

[0095] In Step 6, the time for the third rapid cooling of the ceramic slurry with liquid nitrogen is 15s.

[0096] In Step 7, the ceramic slurry block is subjected to vacuum freeze-drying at a temperature of -10°C, a vacuum degree of 13 Pa, and a time of 15 h.

[0097] In Step 9, the roasting process of the cylindrical ceramic slurry block is as follows: First, the cylindrical ceramic slurry block is placed in a roasting furnace and heated from room temperature to 900°C at a rate of 15°C / min; then, it is heated from 900°C to 1500°C at a rate of 5°C / min and held at this temperature for 40 min; finally, it is cooled from 1500°C to room temperature at a rate of 15°C / min, and the cylindrical ceramic slurry block is cooled with the furnace.

[0098] In Step 10, the cuboid sample has a length of 1 cm, a width of 1 cm, and a height of 3 cm.

[0099] Comparative Example 1:

[0100] In this comparative example, the ceramic slurry was prepared using the material ratio and preparation method of Example 1. A portion of the ceramic slurry was placed in a cylindrical container and then dried in an oven at a drying temperature of 80°C for 6 h. After drying, the cylindrical ceramic slurry block was taken out of the container. The inner cavity diameter of the cylindrical container is 5 cm, and the height of the ceramic slurry in the container is 3.5 cm.

[0101] A cuboid sample with a length of 1 cm, a width of 1 cm, and a height of 2.5 cm was cut from the central part of the cylindrical ceramic slurry block by wire cutting, and the cuboid sample was evenly divided into two parts in the height direction. The interface was used as the detection plane for the phase detection of the ceramic slurry block.

[0102] Comparative Example 2:

[0103] In this comparative example, the ceramic slurry was prepared using the material ratio and preparation method of Example 1, and then the prepared ceramic slurry was used to prepare a ceramic shell. The preparation process and process parameters of the ceramic shell are all traditional methods. The refractory sand used in this example is corundum sand with a particle size of 100 mesh. A cuboid sample with a length of 1 cm, a width of 1 cm, and a height of 2.5 cm was cut from the central part of the ceramic shell by wire cutting, and the cuboid sample was evenly divided into two parts in the height direction. The interface was used as the detection plane for the phase detection of the ceramic shell.

[0104] The microstructures of the detection planes of the above examples and comparative examples were detected by scanning electron microscopy under the same detection environment and conditions. The microstructure of the detection plane of the ceramic slurry block in Example 1 is as Figure 2 shown, the microstructure of the detection plane of the ceramic slurry block in Comparative Example 1 is as Figure 4 shown, and the microstructure of the detection plane of the ceramic shell in Comparative Example 2 is as Figure 6 shown.

[0105] The phase detection of the detection planes of the above-mentioned examples and comparative examples was carried out by means of X-ray diffraction. The detection environment and detection conditions were the same. The X-ray diffraction results of the detection plane of the ceramic slurry block in Example 1 are as follows Figure 3 shown. The X-ray diffraction results of the detection plane of the ceramic slurry block in Comparative Example 1 are as follows Figure 5 shown. The X-ray diffraction results of the detection plane of the ceramic shell in Comparative Example 2 are as follows Figure 7 shown.

[0106] It can be seen from the figures that after the ceramic slurry in Example 1 was subjected to multiple rapid quenching with liquid nitrogen, vacuum freeze-drying and roasting treatments, the phase detection of the ceramic slurry block was carried out, and the test results showed that the phase changed significantly; the ceramic slurry in Comparative Example 1 was only naturally dried and did not undergo rapid quenching with liquid nitrogen and vacuum freeze-drying, and stratification occurred in the obtained ceramic slurry block; in Comparative Example 2, the ceramic shell was detected, and the ceramic shell carried sand, and the phase results were blocked.

[0107] The silica sol (model FSI silica sol) used in the above-mentioned examples and comparative examples was purchased from Zhejiang Yuda Chemical Co., Ltd., the organosilane defoamer was purchased from Shandong Dinghong New Materials Co., Ltd., the gemini-based siloxane wetting agent (model LW-4100) was purchased from Dongguan Good New Materials Co., Ltd., and other chemical reagents, powder materials, etc. were purchased from Aladdin Reagent Co., Ltd. and Sinopharm Chemical Reagent Co., Ltd.

[0108] Special note: The technical solution of the present invention involves many parameters. It is necessary to comprehensively consider the synergistic effects between the various parameters 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 through a large number of experiments. For each parameter and the mutual combination of the various parameters, the inventor has recorded a large number of experimental data. Due to space limitations, the specific experimental data are not disclosed here.

[0109] It is not difficult for those skilled in the art to understand that the method for detecting the phase of the ceramic shell applicable to precision casting of the present invention includes any combination of the invention content and the specific implementation part of the present invention specification and the various parts shown in the drawings. Due to space limitations and to make the specification concise, the various solutions formed by 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 within the protection scope of the present invention.

Claims

1. A method for detecting the phase of a ceramic mold shell applicable to precision casting, characterized in that: Instead of directly detecting the phase of the ceramic shell mold, the phase of the ceramic slurry is detected. The detection method includes the following steps in sequence: Step 1: Prepare the ceramic slurry for preparing the ceramic shell mold according to the designed material ratio; Step 2: Take out a part of the prepared ceramic slurry and put it into a mixing container, and then put the mixing container containing the ceramic slurry into a biaxial rotating mixing device to perform pre-dispersion treatment on the ceramic slurry; Step 3: Take out a part of the pre-dispersed ceramic slurry and put it into a cylindrical transparent container, and then use a sealing film to cover and seal the opening of the cylindrical transparent container. At this time, the ceramic slurry is in a flowing state; Step 4: Use a clamping tool to vertically put the covered and sealed cylindrical transparent container into a liquid nitrogen bucket, and make the cylindrical transparent container completely immersed in liquid nitrogen to perform the first liquid nitrogen rapid cooling on the ceramic slurry; after the first liquid nitrogen rapid cooling is completed, use a clamping tool to vertically take out the cylindrical transparent container and place it on a horizontal ground to let the ceramic slurry stand still; Step 5: Use a clamping tool to vertically put the cylindrical transparent container into the liquid nitrogen bucket again, and make the cylindrical transparent container completely immersed in liquid nitrogen to perform the second liquid nitrogen rapid cooling on the ceramic slurry; after the second liquid nitrogen rapid cooling is completed, use a clamping tool to vertically take out the cylindrical transparent container and place it on a horizontal ground to let the ceramic slurry stand still; Step 6: Use a clamping tool to vertically put the cylindrical transparent container into the liquid nitrogen bucket again, and make the cylindrical transparent container completely immersed in liquid nitrogen to perform the third liquid nitrogen rapid cooling on the ceramic slurry; after the third liquid nitrogen rapid cooling is completed, use a clamping tool to take out the cylindrical transparent container. At this time, the ceramic slurry is completely frozen and formed into a ceramic slurry block, and the ceramic slurry changes from the initial flowing state to a solid state; Step 7: Uniformly punch out some holes in the sealing film at the opening of the cylindrical transparent container, and then put the cylindrical transparent container into a freeze dryer to perform vacuum freeze drying on the ceramic slurry block, so that the solid moisture inside the ceramic slurry block sublimes into gas and escapes; Step 8: Repeat the operations in Step 4 to Step 7. After repeating one to two times, the solid moisture in the ceramic slurry block can be completely removed, and then take out the ceramic slurry block from the cylindrical transparent container. The ceramic slurry block is cylindrical; Step 9: Put the cylindrical ceramic slurry block into a roasting furnace for roasting treatment; Step 10: After the roasting treatment is completed, use wire cutting to cut a cuboid sample from the central part of the cylindrical ceramic slurry block, and evenly divide the cuboid sample into two parts in the height direction, and use the interface as the detection plane for the phase detection of the ceramic slurry block; Step 11: Use X-ray diffraction to perform phase detection on the detection plane.

2. The method for detecting the phase of a ceramic mold shell applicable to precision casting according to claim 1, characterized in that: In Step 1, the ceramic slurry is composed of fused white corundum powder, silica sol, cyanite, defoamer and wetting agent. The mass ratio of the fused white corundum powder to the silica sol is 3.5 - 4:

1. The addition amount of the cyanite is 2 - 3% of the mass of the fused white corundum powder. The addition amount of the defoamer is 3 - 5% of the mass of the silica sol. The addition amount of the wetting agent is 3 - 5% of the mass of the silica sol; The median particle size of the fused white corundum powder is 20 - 30μm; the SiO2 content in the silica sol is 20 - 30wt%; the mass percentages of each substance in the defoamer are: organosilane defoamer 45 - 55wt%, n-octanol 45 - 55wt%; the wetting agent is a gemini-based siloxane wetting agent; The preparation method of the ceramic slurry is as follows: First, mix the organosilane defoamer and n-octanol evenly at room temperature to obtain the defoamer; then put the silica sol, defoamer and wetting agent into a reaction kettle and stir. The stirring temperature is 20 - 25°C and the stirring time is 10 - 30min to make the three substances fully blend; finally, put the cyanite and fused white corundum powder into the reaction kettle and continue to stir. The stirring temperature is 20 - 25°C and the stirring time is 1 - 5h to obtain the ceramic slurry; the flow cup viscosity of the ceramic slurry is 10 - 30s.

3. The method for detecting the phase of the ceramic mold shell applicable to precision casting according to claim 2, characterized in that: In Step 2, the mass of the ceramic slurry put into the mixing container is 500 - 700g, the temperature of the pre-dispersion treatment is room temperature, the speed is 400 - 500r / min, and the time is 12 - 15h.

4. The method for detecting the phase of a ceramic mold shell applicable to precision casting according to claim 3, characterized in that: In Step 3, the inner cavity diameter of the cylindrical transparent container is 5cm. Put the ceramic slurry into the cylindrical transparent container, and the height of the ceramic slurry is 3 - 4cm.

5. The method for detecting the phase of a ceramic mold shell applicable to precision casting according to claim 4, characterized in that: In Step 4, the time for the first liquid nitrogen rapid cooling of the ceramic slurry is 20 - 30s, and the standing time after taking out the ceramic slurry is 3 - 5s.

6. The method for detecting the phase of the ceramic mold shell applicable to precision casting according to claim 5, characterized in that: In Step 5, the time for the second liquid nitrogen rapid cooling of the ceramic slurry is 10 - 15s, and the standing time after taking out the ceramic slurry is 3 - 5s.

7. The method for detecting the phase of a ceramic mold shell applicable to precision casting according to claim 6, wherein: In Step 6, the time for the third liquid nitrogen rapid cooling of the ceramic slurry is 10 - 15s.

8. The method for detecting the phase of a ceramic mold shell applicable to precision casting according to claim 7, characterized in that: In Step 7, the ceramic slurry block is subjected to vacuum freeze-drying. The temperature is -50 to -10°C, the vacuum degree is 1.3 - 13Pa, and the time is 12 - 15h.

9. The method for detecting the phase of a ceramic mold shell applicable to precision casting according to claim 8, wherein: In Step 9, the baking treatment process of the cylindrical ceramic slurry block is as follows: First, put the cylindrical ceramic slurry block into a baking furnace and raise the temperature from room temperature to 900°C at a speed of 15 - 20°C / min; then raise the temperature from 900°C to 1400 - 1500°C at a speed of 5 - 10°C / min and keep it warm for 30 - 40min; finally, lower the temperature from 1400 - 1500°C to room temperature at a speed of 15 - 20°C / min, and the cylindrical ceramic slurry block cools with the furnace.

10. The method for detecting the phase of the ceramic mold shell applicable to precision casting according to claim 9, wherein: In Step 10, the length of the cuboid sample is 1cm, the width is 1cm, and the height is 2 - 3cm.

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