Preparation method of Hf-C-N composite material superhigh-temperature ceramic crucible and method for preparing blade by using crucible

Abstract

The invention discloses a preparation method of an Hf-C-N composite material ultrahigh-temperature ceramic crucible and a method for preparing blades by using the crucible, and relates to the technical field of electromagnetic metallurgy. The invention solves the problems of high oxygen adsorption and ceramic inclusion pollution in an alloy matrix caused by long-term interaction of the existing molten alloy and ceramic crucible, and the problem that the industrial size of the market demand cannot be met. The refractory material Hf-C-N is used, the refractory material Hf-C-N is high in melting point and has high phase stability, mechanical performance and ablation resistance, the influence of a ceramic material on melt pollution and structure control is avoided, and the inner wall of the crucible is coated with the HfC-20wt% SiC coating and the SiC coating capable of enhancing the binding force between the HfC-20wt% SiC coating and the inner wall of a body. And the interaction between the alloy and the crucible is effectively controlled. And the prepared alloy has the characteristics of large size, good uniformity and convenience in subsequent processing. The method is used for preparing the directional solidification Nb-Si alloy.

Description

Technical Field

[0001] The present invention relates to the field of composite materials and their preparation, and in particular to a method for preparing a Hf-CN composite ultra-high temperature ceramic crucible and a method for preparing a blade using the crucible. The blade prepared by the present invention is an equiaxed crystal blade of a Nb-Si based alloy. Background Art

[0002] Since electromagnetic cold crucible technology has the advantages of being able to melt high-melting-point, active materials and preparing materials with uniform composition, it has been widely used in material smelting and preparation. The current electromagnetic cold crucible directional solidification has broad application prospects in the aerospace and automotive industries.

[0003] However, the materials used in the current electromagnetic cold crucible are commercial ceramic materials (such as Al2O3, ZrO2, CaO). The production of Nb-Si alloy ingots is carried out under the action of the electromagnetic field. The material is gradually melted by induction heating and forms a liquid hump under the combined action of electromagnetic thrust, surface tension, gravity and pressure. After the directional solidification begins, the material is fed and pulled according to the principle of equal feeding and pulling volumes.

[0004] During the process of directional solidification to produce Nb-Si alloys, the inevitable lateral heat dissipation will cause the molten alloy to contact the ceramic crucible. Long-term interaction leads to high oxygen adsorption in the alloy matrix and ceramic inclusion contamination. Dissolution and corrosion are the main mechanisms of alloy-crucible interaction, which increase with increasing heating temperature and action time. As a result, the microstructure and mechanical properties of the alloy deteriorate. Compared with Al2O3 or ZrO2 (another important crucible material), CaO is cheaper and has better thermochemical inertness, but its strong hydration tendency limits its practical application.

[0005] In addition, with the gradual expansion of the application scope of electromagnetic cold crucible directional solidification alloys and the demand for industrial engine blade production, the market's requirements for the cross-sectional size of ingots have changed from small to large, and there is an urgent need to develop large-size ingots. However, it is difficult to control the process conditions of large-size castings during the production process, resulting in a low qualified finished product rate for large-size castings.

[0006] Based on the above considerations, it is necessary to develop a new generation of ceramic crucibles for the production of high-quality industrial-grade alloys.

[0007] In summary, the long-term interaction between the existing molten alloy and the ceramic crucible leads to the problems of high oxygen adsorption in the alloy matrix and ceramic inclusion contamination, as well as the problem of industrial size that cannot meet market demand. Summary of the invention

[0008] The purpose of the present invention is to solve the problems of high oxygen adsorption and ceramic inclusion contamination in the alloy matrix caused by the long-term interaction between the existing molten alloy and the ceramic crucible, as well as the problem of industrial size that cannot meet market demand. Further, a method for preparing an ultra-high temperature ceramic crucible of Hf-CN composite material and a method for preparing a blade using the crucible are provided.

[0009] The technical solution of the present invention is:

[0010] A method for preparing a Hf-CN composite material ultra-high temperature ceramic crucible comprises the following steps:

[0011] Step 1: The crucible material is selected from Hf-CN ultra-high temperature ceramic material, and Hf and C powders are ground by a high-energy ball mill under an argon atmosphere;

[0012] Step 2: Mechanically induce the ground Hf and C powders to undergo composite combustion in a nitrogen atmosphere;

[0013] Step 3: Sintering the synthesized powder after combustion in a nitrogen atmosphere for 5 to 7 minutes by spark plasma sintering to prepare Hf-CN ultrahigh temperature ceramic material;

[0014] Step 4: Making the Hf-CN ultra-high temperature ceramic material into a crucible body.

[0015] Furthermore, it also includes step five: coating the inner wall of the crucible body with a HfC-20wt% SiC coating, and coating a SiC coating between the inner wall of the crucible body and the HfC-20wt% SiC coating to enhance the bonding strength between the HfC-20wt% SiC coating and the inner wall of the crucible body.

[0016] Furthermore, the HfC-20wt%SiC coating in step 5 includes the following steps:

[0017] Step 51: Weigh Si powder and C powder according to the mass ratio, and take them out after ball milling;

[0018] Step 52: Mix the crucible body with the powder, and ensure that the inner side of the crucible body is completely and evenly covered by the powder;

[0019] Step 53: placing the crucible body into a high-temperature vacuum sintering furnace to prepare a SiC coating;

[0020] Step 54: The HfC and SiC powders are granulated by a spray granulation method, and a mixture of 80% by mass of HfC particles and 20% by mass of SiC particles after granulation is used as a precursor, and a HfC-SiC coating is prepared on the inner wall of the crucible by a supersonic plasma spraying method.

[0021] Furthermore, the molar ratio of Hf powder to C powder in step 1 is 2:1, the ratio of steel balls to Hf powder and C powder during ball milling is 20:1, and the grinding time is 2 h.

[0022] Preferably, the ammonia pressure in step 2 is 1 Pa, and the powder is locally preheated to initiate combustion synthesis.

[0023] Furthermore, in step three, a load of 50 MPa is continuously applied to the sample after the sectioning, the heating rate is 100° C. / min, the temperature is 1800° C., and the residence time is 15 min.

[0024] Preferably, the crucible manufacturing technology adopted in step 4 is a mortar casting method.

[0025] Preferably, the SiC particles in step 5-1 are ground in ethanol for 24 hours. The slurry is dried in an evaporator at 90° C. The dried mixture is then ball-milled for 24 hours.

[0026] Furthermore, the crucible containing the powder in step 53 is sintered at 1900-2300° C. for 5 minutes and kept in a vacuum atmosphere at 1100-1500° C. for 8 hours.

[0027] The present invention also provides a method for preparing a single crystal Nb-Si alloy for blades, which comprises the following steps:

[0028] Step 1: Install the crucible and the material, connect the induction coil to the electrode, connect the bottom bracket to the pull rod, connect the crucible to the positioning water outlet, connect the feeding rod to the feeding rod, and adjust the coil, the bottom bracket and the feeding rod to the predetermined position, and then install the feeding rod and the prepared crucible;

[0029] Step 2: Auxiliary measures and inspections, using crucible pads and feeding positioning brackets as aids, check the position of each component and clean the furnace and electrodes before closing the furnace door;

[0030] Step 3: Close the furnace door and exhaust valve, start the mechanical pump to evacuate; start the vacuum system to pump the air pressure in the furnace to below 1Pa, and then recoil high-purity argon gas into the furnace to 300Pa. Repeat this process 3-5 times;

[0031] Step 4: Turn on the power supply and the cooling water valve of the cold crucible, start the circulating water cooling system and check whether the water supply to the crucible and power supply is normal, and then turn on the main power supply;

[0032] Slowly adjust the power supply voltage to gradually increase the output power. First, adjust the power supply output voltage to 100V at a uniform speed. Then, increase 20V per minute in the range of 100-200V, add 10V per minute in the range of 200-300V, and add 5V every half minute above 300V until the required power is adjusted. Adjust the feeding speed and the downward pulling speed, start melting, and directionally solidify in the gallium-indium liquid.

[0033] Step 5: After the ingot is pulled to the predetermined length, the power is slowly unloaded, and then the heating power is disconnected. After the sample is sufficiently cooled, the cooling system is closed, air is introduced, and the furnace door is opened to take samples. When the ingot is pulled to the predetermined length, the feeding and pulling system can be stopped, and then quenching is performed to retain the solidification interface and solidification structure, thereby obtaining a directionally solidified Nb-Si based alloy equiaxed crystal blade.

[0034] Compared with the prior art, the present invention has the following effects:

[0035] 1. The present invention changes the material of the crucible and prolongs its service life. The refractory material Hf-CN is used, which has a high melting point, high phase stability, mechanical properties and ablation resistance. The influence of traditional ceramic materials on melt contamination and structure control can be avoided, and the interaction between the alloy and the crucible can be controlled.

[0036] 2. The present invention also has a HfC-20wt% SiC coating and a SiC coating that can enhance the bonding between the HfC-20wt% SiC coating and the inner wall of the body on the inner wall of the crucible. The coating will form dense HfSiO4 on the inner wall of the crucible, and because it has high oxidation resistance at high temperatures, it can effectively avoid high oxygen adsorption.

[0037] 3. The alloy produced by the crucible of the present invention has a diameter of about 500mm-550mm, which lays a foundation for further forging of the ingot and improves the machinability of the ingot. It can realize the manufacture of large-size equiaxed crystal blades, meet production needs, and facilitate industrial large-scale production and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The sample tissue image is obtained by grinding, polishing and corroding the ingot produced by traditional copper crucible, and then observing the tissue using a scanning electron microscope (SEM).

[0039] Figure 2 The sample tissue picture is obtained by grinding, polishing and corroding the ingot produced by Hf-CN crucible, and then observing the sample tissue using a scanning electron microscope (SEM).

[0040] Figure 3 It is a structural schematic diagram of the vacuum non-consumable electromagnetic cold crucible directional solidification equipment of the present invention. DETAILED DESCRIPTION

[0041] Specific implementation method 1: Combination Figures 1 to 3 To illustrate this embodiment, the embodiment includes the following steps:

[0042] Step 1: The crucible material is Hf-CN ultra-high temperature ceramic material, and Hf and C powders are ground by a high-energy ball mill under argon atmosphere. The molar ratio of Hf powder to C powder is 2:1, the ratio of steel balls to HfC powder during ball milling is 20:1, and the grinding time is 2h;

[0043] Step 2: Mechanically induced milled Hf and C powders were compositely burned by local preheating in a nitrogen atmosphere at a pressure of 1 Pa;

[0044] Step 3: The synthetic powder after combustion was sintered in a nitrogen atmosphere by spark plasma sintering for 5 to 7 minutes, and a load of 50 MPa was continuously applied to the sintered sample. The heating rate was 100 ° C / min, the temperature was 1800 ° C, and the residence time was 15 minutes to prepare Hf-CN ultra-high temperature ceramic material;

[0045] Step 4: The Hf-CN ultra-high temperature ceramic material is made into a crucible body by a mortar casting method.

[0046] The crucible body prepared in this embodiment is Figure 3 The water-cooled crucible 4 is installed in the smelting furnace 10. The present invention makes the water-cooled crucible 4 have ablation resistance by changing the material of the water-cooled crucible 4 and spraying the coating on the structure, thereby avoiding the influence of traditional ceramic materials on melt contamination and structure control.

[0047] Specific implementation method 2: Combination Figures 1 to 3 To illustrate this embodiment, this embodiment also includes step five: coating the inner wall of the crucible body with a HfC-20wt% SiC coating, and providing a SiC coating between the inner wall of the crucible body and the HfC-20wt% SiC coating to enhance the bonding strength between the HfC-20wt% SiC coating and the inner wall of the crucible body.

[0048] In this way, the present invention uses the refractory material Hf-CN, which has a high melting point, high phase stability, mechanical properties and ablation resistance, to avoid the influence of traditional ceramic materials on melt contamination and organizational control, and the inner wall of the crucible is also coated with a HfC-20wt% SiC coating and a SiC coating that can enhance the bonding force between the HfC-20wt% SiC coating and the inner wall of the crucible body. The interaction between the alloy and the crucible can be effectively controlled. The prepared alloy has the characteristics of good uniformity and convenient subsequent processing. The present invention is used for the preparation of directional solidification Nb-Si alloy. Other components and connection relationships are the same as those in the first specific embodiment.

[0049] Specific implementation method three: Combination Figures 1 to 3 To illustrate this embodiment, the HfC-20wt% SiC coating and the SiC coating in step 5 of this embodiment include the following steps:

[0050] Step 51: Weigh the SiC particles and take them out after ball milling;

[0051] Step 52: Mix the crucible body with the powder, and ensure that the inner and outer sides of the crucible body are completely and evenly covered by the powder;

[0052] Step 53: Place the crucible body into a high-temperature vacuum sintering furnace to prepare a SiC coating;

[0053] Step 54: The HfC and SiC powders are granulated by a spray granulation method, and a mixture of 80% by mass of HfC particles and 20% by mass of SiC particles after granulation is used as a precursor, and a HfC-SiC coating is prepared on the inner wall of the crucible by a supersonic plasma spraying method.

[0054] Such arrangement can enhance the bonding force between the HfC-20wt% SiC coating and the inner wall of the crucible body. Other components and connection relationships are the same as those of the first or second specific implementation.

[0055] Specific implementation method four: Combination Figures 1 to 3 To illustrate this embodiment, the molar ratio of Hf powder to C powder in step 1 of this embodiment is 2:1, the ratio of steel balls to Hf powder and C powder during ball milling is 20:1, and the grinding time is 2 hours. With such settings, a finer powder can be obtained, and the other compositions and connection relationships are the same as any one of the specific embodiments 1 to 3.

[0056] Specific implementation method five: Combination Figures 1 to 3 To illustrate this embodiment, the ammonia pressure in step 2 of this embodiment is 1 Pa, and the powder is locally preheated to initiate combustion synthesis.

[0057] Such arrangement can control the reaction conditions and optimize the product quality. The other structures and compositions are the same as any one of the specific embodiments 1 to 4.

[0058] Specific implementation method six: Combination Figures 1 to 3 To illustrate this embodiment, in step three of this embodiment, a load of 50 MPa is continuously applied to the sample, the heating rate is 100° C. / min, the temperature is 1800° C., and the residence time is 15 min.

[0059] Such arrangement can improve the reaction rate and the compactness of the product and ensure that the reaction proceeds fully. The other components and connection relationships are the same as any one of the specific embodiments 1 to 3.

[0060] Specific implementation method seven: Combination Figures 1 to 3 To illustrate this embodiment, the crucible manufacturing technology used in step 4 of this embodiment is a mortar casting molding method. This method can effectively produce high-quality crucibles suitable for high-temperature environments. Other components and connection relationships are the same as any one of the specific embodiments 1 to 6.

[0061] Specific implementation method eight: Combination Figure 1 and Figure 2 In this embodiment, the step 53 of this embodiment wraps the SiC

[0062] The crucible of the powder was sintered at 1900-2300 °C for 5 min and kept at 1100–1500 °C in a vacuum atmosphere for 8 h.

[0063] Such arrangement promotes the rapid sintering of SiC powder and improves the compactness of SiC coating. Other components and connection relationships are the same as any one of the specific embodiments 1 to 8.

[0064] In addition, the spraying process current in step 54 of the present invention is 400A and the spraying voltage is 150V, which can ensure the uniformity and density of the coating.

[0065] Specific implementation method ten: Combination Figure 1 , Figure 2 and Figure 3 The present embodiment is described. The blade preparation method of the present embodiment comprises the following steps:

[0066] Step 1: Install the crucible and the material. Connect the induction coil 6 to the electrode 9, connect the bottom bracket 7 to the pull rod 8, connect the crucible 4 to the positioning water port 13, connect the feed rod 2 to the feed rod 1, and adjust the coil, bottom bracket, and feed rod to the predetermined position. Then install the feed rod 2 and the crucible prepared by the preparation method of the Hf-CN composite material ultra-high temperature ceramic crucible 4 described in any one of claims 1 to 9;

[0067] Step 2: Auxiliary measures and inspection. Use the crucible pad 14 and the feeding positioning bracket 3 as an aid to check the position of each component and clean the furnace and electrodes before closing the furnace door;

[0068] Step 3: Close the furnace door and exhaust valve, start the mechanical pump to evacuate; start the vacuum system to pump the air pressure in the furnace to below 1Pa, and then recoil high-purity argon gas into the furnace to 300Pa. Repeat this process 3-5 times;

[0069] Step 4: Turn on the power supply and the cooling water valve of the cold crucible, start the circulating water cooling system and check whether the water supply to the crucible and power supply is normal, and then turn on the main power supply;

[0070] Slowly adjust the power supply voltage to gradually increase the output power. First, adjust the power supply output voltage to 100V at a uniform speed, then increase 20V per minute in the range of 100-200V, add 10V per minute in the range of 200-300V, and add 5V every half minute above 300V until the required power is adjusted. Adjust the feeding speed and the downward pulling speed, start melting, and directionally solidify in the gallium-indium liquid;

[0071] Step 5: After pulling to the predetermined length, slowly unload the power and then disconnect the heating power. After the sample is sufficiently cooled, close the cooling system, let in air, and open the furnace door to take samples. When the ingot is pulled to the predetermined length, the feeding and pulling system can be stopped, and then quenching is performed to retain the solidification interface and solidification structure, thereby obtaining a directionally solidified Nb-Si based alloy equiaxed crystal blade.

[0072] Such an arrangement can optimize the directional solidification process and ensure that a high-quality alloy can be obtained. Other compositions and connection relationships are the same as any one of the specific embodiments 1 to 8.

[0073] The vacuum non-consumable electromagnetic cold crucible directional solidification equipment in step 1 includes a melting furnace 10, a feed rod 2, a feed positioning device 3, a water-cooled crucible 4, a vacuum system 5, a water cooling system 11, a coil 6, a bottom support 7, a pulling device 8, a control power supply 9 and an argon gas bottle 15.

[0074] A feed port 1 and an upper observation window 12 are provided at the upper end of the smelting furnace 10, a water cooling system 11 is provided on the side of the smelting furnace 10, a feeding positioning device 3 is installed on the upper part of the smelting furnace 10, a pulling device 8 is installed at the lower end inside the smelting furnace 10, a bottom support 7 is installed on the pulling device 8, and a gallium indium liquid 16 is provided in the bottom support 7, a water-cooled crucible 4 is installed directly above the bottom support 7, a coil 6 is sleeved on the outside of the water-cooled crucible 4, the water cooling system 11, the vacuum system 5, the control power supply 9 and the argon gas bottle 15 are connected to the interior of the smelting furnace 10, and the feed rod 2 passes through the feed port 1 and the feeding positioning device 3 and then extends into the water-cooled crucible 4.

[0075] The top of the feeding rod 2 is connected to the feeding positioning device 3, and the bottom of the feeding rod 2 is at the same height as the upper part of the coil 6. The lower part of the bottom support 7 is in the gallium-indium liquid 16 and is connected to the pulling device 8.

[0076] The diameter of the feeding rod 2 is 250 mm, and the diameter of the bottom support 7 is 500 mm. The pressure in the melting furnace 10 is 300 Pa. The power supply voltage is slowly adjusted to gradually increase the output power. The ratio of the feeding speed to the pulling speed is 2:1.

[0077] Combination Figures 1 to 3 The working principle of the present invention is described:

[0078] Combination Figures 1 to 3This embodiment is described. In the preparation process of a Nb-Si based alloy equiaxed crystal blade for directionally solidified, a novel electromagnetic cold crucible is required, which includes the following steps:

[0079] 1. Crucible preparation:

[0080] 1) Grinding Hf and C powders by high energy ball mill under argon atmosphere;

[0081] 2) Mechanically induced combustion of the milled Hf / C composite particles in a nitrogen atmosphere;

[0082] 3) The Hf-CN ultrahigh temperature ceramic material was prepared by rapidly sintering the synthesized powder after combustion in a nitrogen atmosphere through spark plasma sintering (SPS).

[0083] 4) The Hf-CN ultrahigh temperature ceramic material is used to make a crucible by a mortar casting method.

[0084] 5) Weighing SiC particles according to a certain mass ratio and taking them out after ball milling; mixing the crucible product with SiC powder, and ensuring that the crucible is completely and evenly coated with the SiC powder; placing the crucible in a high-temperature vacuum sintering furnace to prepare a SiC coating;

[0085] 6) The HfC and SiC powders were granulated by a spray granulation method, and a mixture of 80% by mass of HfC particles and 20% by mass of SiC particles after granulation was used as a precursor, and a HfC-SiC coating was prepared on the inner wall of the crucible by a supersonic plasma spraying method.

[0086] 2. Alloy casting:

[0087] 1): Start the control power of the electromagnetic cold crucible directional solidification device, screw the adapter into the screw hole of the pulling system, and then install the bottom bracket and the ingot in sequence, followed by the installation of the feeding rod and the cold crucible according to claim 2.

[0088] 2): Close the furnace door and exhaust valve, open the cooling water valve of the mechanical pump and start the mechanical pump to vacuum;

[0089] 3): Turn on the power supply and the cooling water valve of the cold crucible to start the circulating water cooling system;

[0090] 4): Adjust the upper feeding speed and the lower pulling speed as required to carry out melting and directional solidification;

[0091] 5): When the material is pulled to a predetermined length, the feeding and pulling system can be stopped, and then quenching is performed to retain the solidification interface and solidification structure;

[0092] The ingots produced by traditional copper crucibles and Hf-CN crucibles were ground, polished and corroded, and the SEM microstructures were observed using a scanning electron microscope. The results are as follows: Figure 1 , Figure 2 shown.

[0093] The solidification structure of the alloy is mainly composed of primary Nb SS and Nb SS / Nb5Si3 eutectic structure. There are two types of eutectics: fine eutectics in the center of the cell and coarse eutectics at the edge of the cell. The directional solidification structure of the alloy is arranged in parallel along the growth direction. In the longitudinal section, the primary Nb SS The silicides are all arranged along the longitudinal axis; in the cross section, the directional structure of the alloy melted in the copper crucible is fine and the growth is discontinuous; the growth coupling degree of the alloy eutectic melted in the Hf-CN crucible is relatively high. The above results show that the use of a dense crucible with changed materials can effectively reduce the reaction between the crucible and the alloy, improve the purity of the directionally solidified alloy, and enhance the directional growth effect of the directionally solidified structure of the Nb-Si-based ultra-high temperature alloy.

[0094] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a Hf-CN composite material ultra-high temperature ceramic crucible, characterized in that: It includes the following steps: Step 1: The crucible material is selected from Hf-CN ultra-high temperature ceramic material, and Hf and C powders are ground by a high-energy ball mill under an argon atmosphere; Step 2: Mechanically induce the ground Hf and C powders to undergo composite combustion in a nitrogen atmosphere; Step 3: Sintering the burned synthetic powder in a nitrogen atmosphere for 5 to 7 minutes by spark plasma sintering to prepare Hf-CN ultrahigh temperature ceramic material; Step 4: Making the Hf-CN ultra-high temperature ceramic material into a crucible body.

2. The method for preparing a Hf-CN composite material ultra-high temperature ceramic crucible according to claim 1, characterized in that: It also includes step five: coating the inner wall of the crucible body with a HfC-20wt% SiC coating, and coating a SiC coating between the inner wall of the crucible body and the HfC-20wt% SiC coating to enhance the bonding strength between the HfC-20wt% SiC coating and the inner wall of the crucible body.

3. The method for preparing a Hf-CN composite material ultra-high temperature ceramic crucible according to claim 1, characterized in that: The HfC-20wt%SiC coating in step 5 includes the following steps: Step 51: Weigh an appropriate amount of SiC particles and obtain SiC powder by ball milling; Step 52: Mix the crucible body with the SiC powder, and ensure that the inner side of the crucible body is completely and evenly coated with the SiC powder; Step 53: placing the crucible body wrapped with SiC powder into a high-temperature vacuum sintering furnace to prepare a SiC coating; Step 54: The Hf-C and SiC powders are granulated by a spray granulation method, and a mixture of 80% by mass of HfC particles and 20% by mass of SiC particles after granulation is used as a precursor, and a HfC-SiC coating is prepared on the inner wall of the crucible by a supersonic plasma spraying method.

4. The method for preparing a Hf-CN composite material ultrahigh temperature ceramic crucible according to claim 3, characterized in that: The molar ratio of Hf powder to C powder in step 1 is 2:1, the ratio of steel balls to Hf powder and C powder during ball milling is 20:1, and the grinding time is 2 h.

5. The method for preparing a Hf-CN composite material ultra-high temperature ceramic crucible according to claim 3, characterized in that: The ammonia pressure in step 2 is 1 Pa, and the powder is locally preheated to initiate combustion synthesis.

6. The method for preparing a Hf-CN composite material ultra-high temperature ceramic crucible according to claim 3, characterized in that: In step 3, a load of 50 MPa is continuously applied to the sample, the heating rate is 100°C / min, the temperature is 1800°C, and the residence time is 15 min.

7. The method for preparing a Hf-CN composite material ultrahigh temperature ceramic crucible according to claim 3, characterized in that: The crucible manufacturing technology adopted in step 4 is the mortar casting molding method.

8. The method for preparing a Hf-CN composite material ultra-high temperature ceramic crucible according to claim 3, characterized in that: The SiC particles in step 5-1 were ground in ethanol for 24 h. The slurry was dried in an evaporator at 90° C. The dried mixture was then ball milled for 24 h.

9. The method for preparing a Hf-CN composite material ultra-high temperature ceramic crucible according to claim 3, characterized in that: The crucible containing the powder in step 53 is sintered at 1900-2300°C for 5 minutes and kept in a vacuum atmosphere at 1100-1500°C for 8 hours.

10. A method for preparing a single crystal Nb-Si alloy for blades, characterized in that: It includes the following steps: Step 1: Install the crucible and the material, connect the induction coil (6) to the electrode (9), connect the bottom bracket (7) to the pull rod (8), connect the crucible (4) to the positioning water outlet (13), connect the feed rod (2) to the feed rod (1), and adjust the coil, the bottom bracket and the feed rod to a predetermined position, and then install the feed rod (2) and the crucible prepared by the method for preparing an ultra-high temperature ceramic crucible of a Hf-CN composite material according to any one of claims 1 to 9; Step 2: Auxiliary measures and inspection, using the crucible pad (14) and the feeding positioning bracket (3) as an aid, check the position of each component and clean the furnace and electrodes before closing the furnace door; Step 3: Close the furnace door and exhaust valve, start the mechanical pump to evacuate; start the vacuum system to pump the air pressure in the furnace to below 1Pa, and then recoil high-purity argon gas into the furnace to 300Pa. Repeat this process 3-5 times; Step 4: Turn on the power supply and the cooling water valve of the cold crucible, start the circulating water cooling system and check whether the water supply to the crucible and power supply is normal, and then turn on the main power supply; Slowly adjust the power supply voltage to gradually increase the output power. First, adjust the power supply output voltage to 100V at a uniform speed. Then, increase 20V per minute in the range of 100-200V, add 10V per minute in the range of 200-300V, and add 5V every half minute above 300V until the required power is adjusted. Adjust the feeding speed and the downward pulling speed, start melting, and directionally solidify in the gallium-indium liquid. Step 5: After the ingot is pulled to the predetermined length, the power is slowly unloaded, and then the heating power is disconnected. After the sample is sufficiently cooled, the cooling system is closed, air is introduced, and the furnace door is opened to take samples. When the ingot is pulled to the predetermined length, the feeding and pulling system can be stopped, and then quenching is performed to retain the solidification interface and solidification structure, thereby obtaining a directionally solidified Nb-Si based alloy equiaxed crystal blade.

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