CN114410994A - Based on CaO-MgO-Al2O3Method for smelting nickel-based high-temperature alloy by using refractory material - Google Patents

Abstract

The invention provides a method for melting nickel-based superalloy based on CaO _- MgO _- Al ₂ O ₃ refractory material. The base superalloy raw material is put into the CaO-MgO-Al ₂ O ₃ refractory crucible and smelted in an induction melting device to obtain a nickel-based superalloy. The method for smelting nickel-based superalloy based on CaO-MgO-Al ₂ O ₃ refractory material provided by the invention can effectively prevent oxidation pollution of nickel-based superalloy melt, and smelt nickel-based superalloy with high metallurgical quality.

Description

Method for melting nickel-based superalloy based on CaO-MgO-Al2O3 refractory

technical field

The invention relates to the technical field of nickel-based superalloy smelting, in particular to a method for smelting nickel-based superalloy based on CaO-MgO-Al ₂ O ₃ refractory materials.

Background technique

Nickel-based superalloys are widely used in turbine disks and blades of aero-engines and gas turbines, and are also key materials for the manufacture of major equipment in petrochemical, thermal and nuclear power, energy conservation and environmental protection. Trace elements in nickel-based superalloys can be divided into two categories: beneficial elements and harmful elements. Oxygen exists as a harmful trace impurity element in nickel-based superalloys, and its existing forms are solid solution and oxide inclusions. Since nickel-based superalloys usually contain strong oxide-forming elements such as aluminum, inclusions such as alumina will be formed even if a trace amount of oxygen is contained in the nickel-based alloy liquid. Oxide inclusions are usually the initiation sites and expansion channels of fatigue cracks, which affect the creep and endurance strength of nickel-based superalloys. Therefore, it is of great significance to maintain low oxygen content in nickel-based superalloys.

At present, the vacuum crucible induction melting technology is mostly used for the melting of superalloys. The most commonly used refractory crucibles for smelting are alumina crucibles, magnesia crucibles or calcium oxide crucibles. However, alumina refractory crucibles are used in nickel-based superalloy melts. The dissolution reaction easily occurs in the nickel-based alloy, resulting in the formation of inclusions and affecting the properties of nickel-based alloys. The magnesia refractory crucible is prone to decompose under vacuum conditions, supplying oxygen to the nickel-based alloy melt, and further polluting the nickel-based alloy melt. Although calcium oxide refractory crucible has good thermodynamic stability, it is difficult to be applied on an industrial scale due to its easy hydration.

Therefore, there is an urgent need for a high metallurgical quality nickel-based superalloy smelting method to solve the problem of polluted alloys existing in the induction melting of refractory crucibles such as magnesium oxide, aluminum oxide or calcium oxide to prepare nickel-based superalloys.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a method for smelting nickel-based superalloys with high metallurgical quality based on CaO-MgO-Al ₂ O ₃ refractory materials, using CaO-MgO-Al ₂ O ₃ refractory materials as crucible materials for smelting, and in Vacuum melting is adopted in the induction melting equipment, the melting temperature and time are controlled and the protective atmosphere is used during melting, which can effectively prevent the oxidation pollution of the nickel-based superalloy melt.

In order to solve the above-mentioned technical problems, the present invention provides a method for smelting nickel-based superalloy based on CaO-MgO-Al ₂ O ₃ refractory material, comprising the following steps:

Place the CaO-MgO-Al ₂ O ₃ refractory crucible in the induction melting equipment;

The nickel-based superalloy raw material is put into the CaO-MgO-Al ₂ O ₃ refractory crucible and smelted in an induction melting device to obtain a nickel-based superalloy.

Further, the CaO-MgO-Al ₂ O ₃ refractory crucible is prepared by the following method:

Mixing the raw material powder of the CaO-MgO-Al ₂ O ₃ refractory material with the binder to obtain a mixture;

The mixture is rammed or cold isostatically pressed into a crucible blank;

The crucible green body is baked at high temperature or calcined in a high temperature sintering furnace to obtain a CaO-MgO-Al ₂ O ₃ refractory crucible.

Further, the binder is one or more of borax, paraffin, glycerol and dehydrated alcohol.

Further, the induction melting equipment is a vacuum induction melting furnace, and the vacuum induction melting furnace includes:

A CaO-MgO-Al ₂ O ₃ refractory crucible arranged in an openable spherical furnace;

a hollow copper coil arranged between the inside of the openable spherical furnace and the periphery of the crucible, the hollow copper coil is connected to a power supply box, and circulating water is arranged inside the hollow copper coil;

An asbestos cloth is arranged between the crucible and the hollow copper coil, the asbestos cloth wraps the bottom and the upper part of the crucible, alumina sand is filled between the asbestos cloth and the bottom of the crucible, and the asbestos cloth and the crucible are The upper part is filled with magnesia sand;

The bottom of the asbestos cloth is provided with a tray fixed inside the openable spherical furnace;

The openable spherical furnace chamber is respectively provided with a through hole communicating with the low vacuum pump and a through hole communicating with the high vacuum pump;

The openable spherical furnace is respectively provided with an air inlet connected to the protective gas input device and an air inlet connected to the atmosphere.

Further, the low vacuum pump is a mechanical pump, and the high vacuum pump is a molecular pump.

Further, the smelting of the nickel-based superalloy raw material by the vacuum induction smelting furnace includes the following steps:

Use the mechanical pump to evacuate the interior of the closed vacuum induction melting furnace to 0-20Pa, and then fill the protective gas to 0.01-0.08Mpa through the protective gas input device;

Repeat the above evacuation and inflation operations 2 to 5 times;

Use the high vacuum pump to evacuate the interior of the vacuum induction melting furnace to 0.0001-0.01Pa;

The hollow copper coil is heated with a heating power of 5-8KW by the power supply in the power box, and the heated hollow copper coil heats the nickel-based superalloy raw material in the CaO-MgO-Al ₂ O ₃ refractory crucible to melt;

The hollow copper coil is heated by the power supply in the power box with a heating power of 3-5KW, and the heated hollow copper coil heats and refines the molten nickel-based superalloy raw material.

Further, during the heating and melting process of the nickel-based superalloy raw material, the heating power is first increased at a rate of 1-2KW/h, and when the nickel-based superalloy raw material begins to melt, the vacuum pump is turned off, and the protective gas is filled, and at the same time Increase the heating power to 5-8KW at a speed of 5-10KW/h, and keep the temperature for 0.1-0.5h until the nickel-based superalloy raw materials are melted into molten metal;

The heating power is then reduced to 3-5KW at a speed of 2-5KW/h, and the molten nickel-based superalloy raw material is heated and refined for 0.5-1.5h of heat preservation.

Further, in the process of smelting the nickel-based superalloy raw material in the vacuum induction melting furnace, the smelting temperature is controlled at 1450-1750° C., and the smelting time is 2-15 hours.

Further, the melting temperature in the vacuum induction melting furnace is determined by observation with an infrared thermometer.

Further, the gas pressure of the protective gas in the smelting process is controlled at 1-9×10 ⁴ Pa.

The invention provides a method for melting nickel-based superalloy based on CaO _- MgO _{-Al 2 O 3} refractory material. -MgO-Al ₂ O ₃ refractory material is referred to as CMA material, which is formed by solid solution of CaAl ₁₂ O ₁₉ of magnetoplumbite structure and MgAl ₂ O ₄ of cubic structure at high temperature, including CaAl ₁₂ O ₁₉ and MgAl ₂ O ₄ has the characteristics of high melting point, low thermal conductivity, good thermal insulation, good thermal stability, good thermal shock resistance and excellent slag resistance. It is very stable in a reducing atmosphere (such as in CO). Metal melt (including steel and nickel-based superalloy) and slag have low wetting effect, so CaO-MgO-Al ₂ O ₃ refractory is used as a crucible for nickel-based superalloy smelting, which can effectively reduce the number of crucibles in the smelting process. Refractory contamination of nickel-based superalloy melts.

Furthermore, the present invention provides a method for smelting nickel-based superalloy based on CaO-MgO-Al ₂ O ₃ refractory material. The CaO-MgO-Al ₂ O ₃ refractory crucible containing nickel-based superalloy is placed in a vacuum induction In the smelting of nickel-based superalloys in the melting furnace, the vacuum induction melting process is adopted. By controlling the vacuum conditions, melting temperature and melting time, and using protective atmosphere protection during smelting, and strictly controlling the protective gas pressure, the oxidation pollution of the superalloy melt can be prevented. Can significantly reduce the amount of oxygen contamination in nickel-based superalloys.

At the same time, the present invention provides a method for smelting nickel-based superalloy based on CaO-MgO-Al ₂ O ₃ refractory material, the smelting process is simple, the requirements for process parameters are low, energy consumption and pollution can be reduced, and the requirements of green metallurgy are met. It has high economic benefits and is worthy of popularization and application.

Description of drawings

1 is a flowchart of a method for smelting nickel-based superalloys based on CaO-MgO-Al ₂ O ₃ refractory materials provided in an embodiment of the present invention;

2 is a sequence diagram of placing crucibles and fillers in a vacuum induction melting furnace in a method for smelting nickel-based superalloys based on CaO-MgO-Al ₂ O ₃ refractory materials provided by an embodiment of the present invention;

3 shows the inclusions in nickel-based superalloys obtained by melting nickel-based superalloys using alumina refractory crucibles, magnesia refractory crucibles and CaO-MgO-Al ₂ O ₃ refractory crucibles provided by the embodiments and comparative examples of the present invention area distribution map;

4 shows the inclusions in nickel-based superalloys obtained by melting nickel-based superalloys using alumina refractory crucibles, magnesia refractory crucibles and CaO-MgO-Al ₂ O ₃ refractory crucibles provided by the embodiments and comparative examples of the present invention Quantity distribution map of different sizes.

Detailed ways

Referring to FIG. 1 , a method for smelting nickel-based superalloy based on CaO-MgO-Al ₂ O ₃ refractory material provided by an embodiment of the present invention mainly includes the following steps:

Step 1) Place the CaO-MgO-Al ₂ O ₃ refractory crucible in a vacuum induction melting furnace.

Wherein, the preparation of the CaO-MgO-Al ₂ O ₃ refractory crucible includes the following steps:

(1) The raw material powder of the CaO-MgO-Al ₂ O ₃ refractory material is mixed with a binder to obtain a mixture.

Specifically, the CaO-MgO-Al ₂ O ₃ refractory raw materials, zirconia grinding balls, and anhydrous ethanol are first prepared and added to the ball mill after the mass ratio of raw materials: grinding balls: ethanol is 2:3:0.8. , milled on a planetary ball mill for 8h. Then, it is dried and sieved in an oven at 120° C. to obtain powder, and then the obtained powder is added to the binder and stirred evenly to obtain a mixture. Wherein, the binder is one or more of borax, paraffin, glycerol, and absolute ethanol. As a specific embodiment of the present invention, the obtained powder is mixed with anhydrous ethanol, and the mixture is uniformly stirred to obtain a mixed material.

(2) Ramming the mixture or cold isostatic pressing to form a crucible green body.

As a specific embodiment of the present invention, the obtained mixture is placed in a self-made crucible mold, and a pressure of 140 MPa is applied in a cold isostatic pressing device and the pressure is maintained for 5 minutes to obtain a crucible green body.

(3) The CaO-MgO-Al ₂ O ₃ refractory crucible is obtained by calcining the crucible green body at a high temperature or in a high-temperature sintering furnace.

As a specific embodiment of the present invention, the obtained crucible china is first pre-sintered at 800°C for 6 hours, then sintered at 1400°C for 6 hours, then sintered at 1700°C for 6 hours, and finally cooled to room temperature to obtain CaO- The MgO-Al ₂ O ₃ refractory crucible, wherein the heating and cooling rate during the heating and cooling process is controlled to be 100°C/h.

Step 2) Place the nickel-based superalloy raw material in a CaO-MgO-Al ₂ O ₃ refractory crucible and smelt in an induction melting device to obtain a nickel-based superalloy.

As a specific embodiment of the present invention, the induction melting equipment is a vacuum induction melting furnace.

Referring to FIG. 2, the vacuum induction melting furnace includes a CaO-MgO-Al ₂ O ₃ refractory crucible 7 arranged in an openable spherical furnace (the openable spherical furnace is not shown in FIG. 2 ), which is arranged in the openable spherical furnace The hollow copper coil 3 between the interior and the periphery of the crucible 7 . One end of the hollow copper coil 3 is connected to the power supply box, and the hollow copper coil 3 can be heated by a certain heating power by controlling the power supply in the power supply box, so that the heated hollow copper coil 3 can heat the crucible 7 enclosed within it. Heating of nickel-based superalloys. In order to facilitate cooling, circulating water is provided inside the hollow copper coil 3 .

In addition, an asbestos cloth 2 is provided between the crucible 7 and the hollow copper coil 3 , and the asbestos cloth 2 wraps the bottom and the upper portion of the crucible 7 . Among them, alumina sand 8 is filled between the asbestos cloth 2 and the bottom of the crucible 7 , and magnesia sand 5 is filled between the asbestos cloth 2 and the upper part of the crucible 7 .

The bottom of the asbestos cloth 2 is provided with a tray 1 fixed inside the openable spherical furnace. The tray 1 supports the bottom of the asbestos cloth 2, thereby fixing the crucible 7 wrapped in the asbestos cloth 2.

At the same time, the openable spherical furnace chamber is respectively provided with a through hole communicating with the low vacuum pump and a through hole communicating with the high vacuum pump. The chamber can be evacuated by a low vacuum pump and a high vacuum pump. In addition, the openable spherical furnace is also provided with an air inlet connected to the protective gas input device and an air inlet connected to the atmosphere. The protective gas can be filled into the furnace through the protective gas input device. The gas port exhausts the gas in the furnace.

As a specific embodiment of the present invention, the gas tank inside the protective gas input device is filled with argon gas as the protective gas, and at the same time, the gas flow rate is guaranteed to be stable during output.

As a specific embodiment of the present invention, the low vacuum pump is a mechanical pump, and the high vacuum pump is a molecular pump.

Smelting the nickel-based superalloy raw material in the CaO-MgO-Al ₂ O ₃ refractory crucible 7 using a vacuum induction melting furnace includes the following steps:

(1) First use a mechanical pump to evacuate low vacuum, evacuate the inside of the closed vacuum induction melting furnace to 0-20Pa, and after reaching the optimal vacuum degree, fill the furnace with protective gas to 0.01-0.08Mpa through the protective gas input device .

(2) Then repeat the above-mentioned vacuuming and inflating operations for 2 to 5 times to perform low-vacuum cleaning.

(3) After reaching the optimal number of low-vacuum scrubbing, turn on high-vacuum scrubbing, and use a molecular pump to evacuate the inside of the vacuum induction melting furnace. Repeat at least 1 to 3 times to evacuate the interior of the vacuum induction melting furnace to the maximum. Excellent vacuum degree 0.0001 ~ 0.01Pa.

(4) After the high vacuum scrubbing reaches the optimum vacuum degree, the hollow copper coil 3 is heated by the power supply in the power box with a heating power of 5-8KW, and the heated hollow copper coil 3 will make the CaO-MgO-Al ₂ O ₃ refractory to CaO-MgO-Al 2 O 3 The nickel-based superalloy feedstock in the material crucible is heated to melt. Among them, in the process of heating and melting the nickel-based superalloy raw materials, the heating power is first increased at a speed of 1-2KW/h, and when the nickel-based superalloy raw materials start to melt, the molecular pump is closed and the protective gas is filled, as one of the present invention. In a specific embodiment, the gas pressure of the filled protective gas is controlled at 1˜9×10 ⁴ Pa. At the same time, the heating power is increased to 5-8KW at a speed of 5-10KW/h, and the temperature is kept for 0.1-0.5h until the nickel-based superalloy raw materials are melted into molten metal.

(5) The hollow copper coil 3 is heated by the power supply in the power box with a heating power of 3-5KW, and the heated hollow copper coil heats and refines the molten nickel-based superalloy raw material. Among them, in this process, the heating power when the nickel-based superalloy raw materials are first melted into molten metal is 5-8KW, and the heating power is reduced to 3-5KW at a speed of 2-5KW/h, and the temperature is kept for 0.5-1.5h. Alloy raw materials are heated and refined.

Among them, the smelting temperature in the whole smelting process of the nickel-based superalloy raw material in the vacuum induction smelting furnace is controlled at 1450-1750 ℃, and the smelting time is 2-15 h. Among them, the melting temperature in the vacuum induction melting furnace is observed and determined by an infrared thermometer.

As a specific embodiment of the present invention, in the vacuum induction melting stage, it is best to repeat the low-vacuum scrubbing of the furnace chamber of the vacuum induction melting furnace 3 times.

As a specific embodiment of the present invention, in the vacuum induction melting stage, it is best to repeat the high-vacuum scrubbing of the furnace chamber of the vacuum induction melting furnace twice. And the vacuum degree reached by high-vacuum scrubbing is 3×10 ^-3 Pa.

As a specific embodiment of the present invention, in the vacuum induction melting stage, the pressure in the furnace cavity of the melting furnace under high vacuum is 1-8 × 10 ^-3 Pa, and the pressure in the furnace cavity of the melting furnace under low vacuum is 1-30 Pa. good.

A method for smelting nickel-based superalloy based on CaO-MgO-Al ₂ O ₃ refractory material provided by the present invention will be further described in detail below with examples and comparative examples.

Example 1

Using nickel-based superalloy GH4169 as raw material. The nickel-based superalloy GH4169 was placed in a CaO-MgO-Al ₂ O ₃ refractory crucible, and then the crucible was placed in the hollow copper coil in the hearth of the vacuum induction melting furnace. Vacuum scrubbing, and then carry out 2 high vacuum scrubbing to make the vacuum degree in the furnace chamber of the vacuum induction melting furnace reach 3 × 10 ^-3 Pa, and then heat the hollow copper coil through the power supply in the power box, and then pass the hollow copper coil to the crucible. The inner nickel-based superalloy GH4169 is heated. During the heating and melting process, the heating power was first increased to 1.5KW at a rate of 1KW/h, and when the nickel-based superalloy GH4169 began to melt, a high vacuum of 3×10 ^-3 to 1×10 ^-1 Pa was maintained. At the same time, the heating power is increased to 6.5KW at a speed of 5.5KW/h, and the nickel-based superalloy GH4169 is rapidly melted into molten metal. Then reduce the heating power to 3.5KW at a rate of 2.5KW/h to refine the molten nickel-based superalloy GH4169, keep it at a temperature of 1550 ° C for 0.5h and then cool it naturally, so that the nickel-based superalloy GH4169 solidifies inside the crucible, take out the crucible The solid obtained by internal solidification, the sample obtained at this time is designated A1.

Comparative Example 1

Using nickel-based superalloy GH4169 as raw material. The alloy ingot was placed in the Al ₂ O ₃ crucible of the inner coil of the vacuum induction furnace, and the power was applied under 3 times of low vacuum and 2 times of high vacuum to reach the vacuum degree of 3 × 10 ^-3 Pa, and the high vacuum was maintained at 3 × 10 ^{- 3} to 1×10 ^-1 Pa state. After 6.7KW high-power rapid melting and 3-3.4KW medium-power refining, it was kept at 1550°C for 30min and then cooled inside the crucible, and the sample was marked as A2.

Comparative Example 2

Using nickel-based superalloy GH4169 as raw material. The alloy ingot is placed in the MgO crucible of the inner coil of the vacuum induction furnace, and the power is applied under the vacuum degree of 3×10 ^-3 Pa after 3 times of low vacuum and 2 times of high vacuum, and the high vacuum is maintained at 3×10 ^-3 ～1 ×10 ^-1 Pa state. After 6.7KW high-power rapid melting and 3-3.4KW medium-power refining, it was kept at 1550°C for 30min and then cooled inside the crucible, and the sample was marked as A3.

The properties of the nickel-based superalloy GH4169 samples obtained by smelting in the embodiment of the present invention and the comparative example were tested.

An oxygen/nitrogen analyzer was used to detect the oxygen content of the three samples smelted in the embodiment and the comparative example, respectively. The test results are shown in Table 1. As can be seen from Table 1, Example 1 of the present invention uses a CaO-MgO-Al ₂ O ₃ refractory crucible to obtain the high-temperature nickel-based alloy sample A1 obtained by melting according to the shown smelting process, compared to Comparative Example 1 using Al ₂ O ₃ Crucibles and Comparative Examples 2 High-temperature nickel-based alloy samples A2 and A3 obtained by smelting MgO crucibles, the oxygen content in the alloys is low, thus illustrating the use of CaO-MgO-Al ₂ O ₃ refractory crucibles smelting in the embodiment of the present invention to obtain The nickel-based superalloys are of higher quality.

Table 1

During the smelting process, the nickel-based superalloy obtained by using the CaO-MgO-Al ₂ O ₃ refractory crucible in Example 1 of the present invention showed good purity, and the surface morphology of the alloy after smelting was compared with those of Comparative Examples 1 and 1. Comparative example 2 is cleaner. By dissecting the interface between the nickel-based superalloy and the crucible, it is found that the CaO-MgO-Al ₂ O ₃ refractory material shows obvious non-wetting, which further indicates that CaO-MgO-Al ₂ O ₃ refractory material crucible melting nickel-based superalloy shows better corrosion resistance to nickel-based alloy melt.

Referring to FIG. 3 and FIG. 4 , by comparing the area of inclusions and the distribution of different sizes and numbers of inclusions in the nickel-based superalloys obtained by smelting Example 1, Comparative Example 1 and Comparative Example 2 of the present invention, it can be seen that the present invention The nickel-based superalloy prepared in Example 1 is significantly better than the nickel-based superalloy prepared in Comparative Example 1 and Comparative Example 2.

The invention provides a method for preparing a high metallurgical quality nickel-based superalloy based on a CaO-MgO-Al ₂ O ₃ (CMA) refractory material. The CaO-MgO-Al ₂ O ₃ refractory material is used as the crucible material for melting, and the The control of vacuum smelting process flow, smelting temperature, smelting time and protective gas pressure during smelting can effectively prevent oxidation pollution of nickel-based superalloy melt, and can smelt to obtain nickel-based superalloy with high metallurgical quality.

Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to examples, those of ordinary skill in the art should understand that the technical solutions of the present invention can be Modifications or equivalent substitutions without departing from the spirit and scope of the technical solutions of the present invention should be included in the scope of the claims of the present invention.

Claims (10)

1. a method based on CaO-MgO-Al ₂ O ₃ refractory smelting nickel-based superalloy, is characterized in that, comprises the steps: Place the CaO-MgO-Al ₂ O ₃ refractory crucible in the induction melting equipment; The nickel-based superalloy raw material is put into the CaO-MgO-Al ₂ O ₃ refractory crucible and smelted in an induction melting device to obtain a nickel-based superalloy. 2. The method for smelting nickel-based superalloy based on CaO-MgO-Al ₂ O ₃ refractory material according to claim 1, wherein the CaO-MgO-Al ₂ O ₃ refractory material crucible is prepared by the following method : Mixing the raw material powder of the CaO-MgO-Al ₂ O ₃ refractory material with the binder to obtain a mixture; The mixture is rammed or cold isostatically pressed into a crucible blank; The crucible green body is baked at high temperature or calcined in a high temperature sintering furnace to obtain a CaO-MgO-Al ₂ O ₃ refractory crucible. 3. the method for smelting nickel-based superalloy based on CaO-MgO-Al ₂ O ₃ refractory material according to claim 2, is characterized in that: described binder is borax, paraffin, glycerol, dehydrated alcohol one or more of them. 4. The method for smelting nickel-based superalloy based on CaO-MgO-Al ₂ O ₃ refractory material according to claim 1, wherein the induction melting equipment is a vacuum induction melting furnace, and the vacuum induction melting furnace comprises : A CaO-MgO-Al ₂ O ₃ refractory crucible arranged in an openable spherical furnace; a hollow copper coil arranged between the inside of the openable spherical furnace and the periphery of the crucible, the hollow copper coil is connected to a power supply box, and circulating water is arranged inside the hollow copper coil; An asbestos cloth is arranged between the crucible and the hollow copper coil, the asbestos cloth wraps the bottom and the upper part of the crucible, alumina sand is filled between the asbestos cloth and the bottom of the crucible, and the asbestos cloth and the crucible are The upper part is filled with magnesia sand; The bottom of the asbestos cloth is provided with a tray fixed inside the openable spherical furnace; The openable spherical furnace chamber is respectively provided with a through hole communicating with the low vacuum pump and a through hole communicating with the high vacuum pump; The openable spherical furnace is respectively provided with an air inlet connected to the protective gas input device and an air inlet connected to the atmosphere. 5 . The method for smelting nickel-based superalloys based on CaO-MgO-Al ₂ O ₃ refractory materials according to claim 4 , wherein the low vacuum pump is a mechanical pump, and the high vacuum pump is a molecular pump. 6 . 6. The method for smelting nickel-based superalloy based on CaO-MgO-Al ₂ O ₃ refractory material according to claim 5, characterized in that, the smelting of nickel-based superalloy raw materials in the vacuum induction melting furnace comprises the following steps: Use the mechanical pump to evacuate the interior of the closed vacuum induction melting furnace to 0-20Pa, and then fill the protective gas to 0.01-0.08Mpa through the protective gas input device; Repeat the above evacuation and inflation operations 2 to 5 times; Use the high vacuum pump to evacuate the interior of the vacuum induction melting furnace to 0.0001-0.01Pa; The hollow copper coil is heated with a heating power of 5-8KW by the power supply in the power box, and the heated hollow copper coil heats the nickel-based superalloy raw material in the CaO-MgO-Al ₂ O ₃ refractory crucible to melt; The hollow copper coil is heated by the power supply in the power box with a heating power of 3-5KW, and the heated hollow copper coil heats and refines the molten nickel-based superalloy raw material. 7. the method for smelting nickel-based superalloy based on CaO-MgO-Al ₂ O ₃ refractory material according to claim 6, is characterized in that: During the heating and melting process of the nickel-based superalloy raw material, the heating power is first increased at a rate of 1-2KW/h, and when the nickel-based superalloy raw material begins to melt, the vacuum pump is turned off, and the protective gas is filled, while the heating power is 5-10KW. The heating power is increased to 5-8KW at the speed of /h, and the temperature is kept for 0.1-0.5h until the nickel-based superalloy raw materials are melted into molten metal; The heating power is then reduced to 3-5KW at a speed of 2-5KW/h, and the molten nickel-based superalloy raw material is heated and refined for 0.5-1.5h of heat preservation. 8. The method for smelting nickel-based superalloy based on CaO-MgO-Al ₂ O ₃ refractory material according to claim 7, wherein the vacuum induction melting furnace controls the smelting temperature in the smelting process of nickel-based superalloy raw materials At 1450～1750℃, the smelting time is 2～15h. 9 . The method for smelting nickel-based superalloys based on CaO-MgO-Al ₂ O ₃ refractory materials according to claim 8 , wherein the smelting temperature in the vacuum induction melting furnace is observed and determined by an infrared thermometer. 10 . 10. The method for smelting nickel-based superalloy based on CaO-MgO-Al ₂ O ₃ refractory material according to claim 7, characterized in that: the gas pressure of the protective gas in the smelting process is controlled at 1～9×10 ⁴ Pa .

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