Nickel-cerium intermediate alloy for high-temperature alloy and preparation method of nickel-cerium intermediate alloy

Abstract

The invention discloses a preparation method of a nickel-cerium intermediate alloy for a high-temperature alloy, which comprises the following steps: step 1, drying cerium oxide powder, nickel protoxide powder, aluminum powder, calcium oxide powder and calcium fluoride powder, and then mixing and compacting to obtain a blank; secondly, the blank is placed in an induction heating furnace to be sequentially subjected to argon blowing, preheating, heating to 1400-1500 DEG C and heat preservation, and a nickel-cerium intermediate alloy is obtained; the invention further discloses the nickel-cerium intermediate alloy for the high-temperature alloy. According to the preparation method, nickel protoxide and cerium oxide are reduced through aluminum, calcium oxide and calcium fluoride serve as slag formers, the reduced metal melt is protected, metal slag separation is facilitated, meanwhile, the melt is covered with the slag, volatilization of the cerium element can be effectively avoided, the nickel-cerium intermediate alloy high in purity and uniform in component is obtained, and the nickel-cerium intermediate alloy is suitable for industrial production. The method is suitable for alloy smelting.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy smelting, and in particular relates to a nickel-cerium master alloy for high-temperature alloys and a preparation method thereof. Background Art

[0002] High-temperature alloys are widely used in the military and civilian industries. They are key materials for manufacturing engines and hot end components of gas turbines. Their service temperature is usually above 600°C, and they have good high-temperature strength and oxidation resistance. During the heating process of high-temperature alloys, rare earth elements easily combine with O, N and S elements in the melt to form corresponding oxides, nitrides and sulfides, which float on the surface of the melt to purify the melt and improve the oxidation resistance and corrosion resistance of high-temperature alloys. Since metallic cerium is easily oxidized to form powdered oxides, there is a risk of introducing oxides when adding single cerium directly during the casting process of high-temperature alloys. Therefore, nickel-cerium intermediate alloys are usually used as the source of rare earth elements.

[0003] For example, the Chinese invention patent "A nickel-cerium master alloy and its preparation method" (publication number CN116891963A) prepared the nickel-cerium master alloy by melting the elemental nickel and adding metal cerium, and then using induction heating under the protection of an inert atmosphere. However, since the melting point of metal cerium is much lower than that of metal nickel, adding metal cerium to molten metal nickel can easily cause cerium splashing, resulting in instability in the composition of the final nickel-cerium master alloy and instability in batches. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the above-mentioned prior art and provide a method for preparing a nickel-cerium master alloy for high-temperature alloys. The preparation method uses aluminum to reduce nickelous oxide and cerium oxide, and uses calcium oxide and calcium fluoride as slag-forming agents, which are covered on the melt to isolate the air so as to protect the reduced metal melt and facilitate gold slag separation. At the same time, the slag covering the melt can effectively prevent the volatilization of cerium elements, ensure the accuracy of the final nickel-cerium master alloy composition, and solve the problem of unstable composition and batch of nickel-cerium master alloy prepared in the prior art.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing a nickel-cerium master alloy for high-temperature alloys, characterized in that the preparation method comprises the following steps: Step 1: drying cerium oxide powder, nickelous oxide powder, aluminum powder, calcium oxide powder and calcium fluoride powder, and then mixing and compacting to obtain a blank; Step 2: placing the blank obtained in step 1 in an induction heating furnace for argon purging, preheating, heating to 1400° C. to 1500° C. and keeping warm to obtain a nickel-cerium master alloy.

[0006] The present invention adopts an induction heating furnace as an external heat source for heating, and isolates the air through argon purging to prevent the reduced metal melt from being contaminated by oxygen and nitrogen elements, so as to reduce the impurity content in the melt; by preheating the billet, the gas inside the raw material powder is heated and escaped to promote exhaust, and the argon purging can continuously take away the escaped gas, thereby reducing the impurities inside the nickel-cerium master alloy and preventing a large amount of gas from escaping during the reaction process to cause melt splashing.

[0007] The above-mentioned method for preparing a nickel-cerium master alloy for a high-temperature alloy is characterized in that the mass purity of the cerium oxide powder in step one is above 94%, and the particle size is 80 mesh; the mass content of nickel element in the nickelous oxide powder is not less than 75%, and the particle size is 100 mesh; the mass purity of the aluminum powder is above 98%, and the particle size is 30 mesh; the mass purity of the calcium oxide powder is above 99%, and the particle size is 80 mesh; the mass purity of the calcium fluoride powder is above 99.5%, and the particle size is 80 mesh.

[0008] The invention ensures that the aluminothermic reduction reaction can proceed smoothly by strictly controlling the purity and particle size of the reaction raw materials, and controls the reaction rate to be moderate, thereby avoiding metal splashing and causing a reduction in yield; at the same time, the impurity content can be reduced, which is conducive to obtaining a nickel-cerium intermediate alloy with high purity, uniform composition and few inclusions.

[0009] The above-mentioned method for preparing a nickel-cerium master alloy for high-temperature alloys is characterized in that the drying temperature in step 1 is 70° C. to 160° C., and the drying time is 4 h to 6 h.

[0010] The present invention removes water vapor in the raw materials by drying the raw materials and controlling the drying temperature and time, thereby avoiding a large amount of splashing caused by water vapor evaporation due to high temperature during the reaction process, thereby affecting the yield of the nickel-cerium master alloy.

[0011] The above-mentioned method for preparing a nickel-cerium master alloy for high-temperature alloys is characterized in that the blank in step one is composed of the following components in parts by mass: 11 to 16 parts of cerium oxide, 64 to 70 parts of nickelous oxide, 11 to 14 parts of aluminum powder, 2 to 3 parts of calcium oxide, and 2 to 6 parts of calcium fluoride.

[0012] The present invention improves the fluidity of the slag by controlling the composition ratio of the reaction raw materials to ensure the gold-slag separation effect and avoid the inclusion of oxides and fluorides in the alloy; at the same time, due to the density of the slag (3g / cm 3 ~4g / cm 3 ) has a density far lower than that of the metal melt and can cover the metal to prevent the increase of oxygen and nitrogen content caused by the contact between the metal and the air, thereby obtaining a high-purity nickel-cerium master alloy.

[0013] The above-mentioned method for preparing a nickel-cerium master alloy for high-temperature alloys is characterized in that the mixing speed in step 1 is 30r / min~40r / min, and the mixing time is 30min~60min.

[0014] The invention avoids the segregation of metal elements in the nickel-cerium master alloy by controlling the mixing rotation speed and time, thereby obtaining the nickel-cerium master alloy with uniform composition.

[0015] The above-mentioned method for preparing a nickel-cerium master alloy for high-temperature alloys is characterized in that a tungsten crucible is used in the induction heating furnace in step 2, and the flow rate of the argon purge is 2L / min~4L / min.

[0016] The present invention can avoid the problem of increased O content caused by using an alumina crucible and increased C content caused by using a graphite crucible by setting the material of the reaction container to tungsten, thereby obtaining a high-purity nickel-cerium intermediate alloy; and by controlling the flow rate of argon purge, it is avoided that the flow rate is too fast, resulting in waste of argon and a large amount of heat loss, and the flow rate is too slow, resulting in the argon gas being unable to completely cover the upper part of the heating furnace to isolate the air.

[0017] The above-mentioned method for preparing a nickel-cerium master alloy for high-temperature alloys is characterized in that the preheating process in step 2 is: adjusting the power of the induction heating furnace to 30kW~50kW for preheating for more than 2 minutes.

[0018] The above-mentioned method for preparing a nickel-cerium master alloy for high-temperature alloys is characterized in that the heating process in step 2 is: the power of the heating furnace is increased to 80kW~100kW for melting until the billet is completely melted, and the insulation time is 10min~20min.

[0019] The present invention controls the blank to be kept warm for 10 to 20 minutes after being completely melted, thereby avoiding poor gold-slag separation effect caused by premature cooling of the slag and the metal, allowing the metal to have sufficient sedimentation time and the slag to have sufficient floating time, thereby obtaining a nickel-cerium intermediate alloy without inclusions.

[0020] The above-mentioned method for preparing a nickel-cerium master alloy for high-temperature alloys is characterized in that the nickel-cerium master alloy in step 2 is composed of the following components in mass fraction: Ce 25%~35%, Cu not more than 0.01%, Fe not more than 0.01%, C not more than 0.05%, N not more than 0.01%, O not more than 0.01%, and the balance is Ni.

[0021] Meanwhile, the present invention discloses a nickel-cerium intermediate alloy for high-temperature alloys, which is characterized in that it is obtained by the above-mentioned preparation method.

[0022] Compared with the prior art, the present invention has the following advantages: 1. The present invention adopts aluminum to reduce nickelous oxide and cerium oxide, and uses calcium oxide and calcium fluoride as slag-forming agents to protect the reduced metal melt and facilitate gold slag separation; at the same time, the slag covers the melt, effectively avoiding the volatilization of cerium element, ensuring the accuracy of the composition of the nickel-cerium master alloy, and further ensuring the composition and batch stability of the nickel-cerium master alloy.

[0023] 2. The present invention adopts cerium oxide and nickelous oxide as the source of nickel and cerium elements, and directly prepares the nickel-cerium intermediate alloy by aluminothermic reduction, which can effectively reduce the preparation cost.

[0024] 3. The present invention adopts induction heating as an external heat source. Compared with the traditional aluminum thermal reduction method, the melt can maintain a high temperature for a long time, and the induction heating furnace has a stirring effect on the melt, which is conducive to the floating of oxides and nitrides, and reduces the content of oxides and nitrides in the nickel-cerium intermediate alloy; and the preheating and melting process are protected by argon purging to prevent the metal melt from being contaminated by oxygen and nitrogen elements, so as to obtain a nickel-cerium intermediate alloy with high purity and uniform composition.

[0025] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a microscopic image of the nickel-cerium master alloy in Example 1 of the present invention.

[0027] Figure 2 This is a nickel element distribution diagram of the nickel-cerium master alloy in Example 1 of the present invention.

[0028] Figure 3 This is a distribution diagram of the cerium element in the nickel-cerium master alloy in Example 1 of the present invention. DETAILED DESCRIPTION

[0029] The mass purity of the cerium oxide powder used in Examples 1 to 4 is all above 94%, and the particle size is all 80 mesh; the mass content of nickel element in the nickelous oxide powder is not less than 75%, and the particle size is all 100 mesh; the mass purity of the aluminum powder is all above 98%, and the particle size is all 30 mesh; the mass purity of the calcium oxide powder is all above 99%, and the particle size is all 80 mesh; the mass purity of the calcium fluoride powder is all above 99.5%, and the particle size is all 80 mesh.

[0030] Example 1 The preparation method of this embodiment comprises the following steps: Step 1: Dry cerium oxide powder, nickelous oxide powder, aluminum powder, calcium oxide powder and calcium fluoride powder at 70°C for 4 hours, then place in a V-type mixer for mixing for 30 minutes, and compact to obtain a blank; the blank is composed of the following components by mass: 16 parts of cerium oxide, 65 parts of nickelous oxide, 11 parts of aluminum powder, 3 parts of calcium oxide, and 2 parts of calcium fluoride; the speed of the V-type mixer is 30r / min; Step 2: placing the blank obtained in step 1 in a tungsten crucible of an induction heating furnace for purging with argon at a flow rate of 2L / min, adjusting the power of the induction heating furnace to 30kW for preheating for 2min, and then adjusting the power to 80kW, raising the heating temperature to 1400°C-1500°C for heating, and obtaining a melt after the blank is completely melted. The melt is kept warm so that the molten state is maintained for 10min, and then the heating function of the induction heating furnace is turned off. After the melt solidifies and the temperature is lower than 800°C, the argon is turned off, and the upper slag is separated after air cooling, and finishing, screening and inspection are performed to obtain a nickel-cerium intermediate alloy; the argon quality purity is 99.99%.

[0031] The microstructure and energy spectrum analysis of the nickel-cerium master alloy prepared in this embodiment are as follows: Figures 1 to 3 As shown, the nickel element and the cerium element are evenly distributed in the nickel-cerium master alloy. The element content of the nickel-cerium master alloy is tested, and the test results are shown in Table 1.

[0032] Table 1 Element mass content of the nickel-cerium master alloy prepared in Example 1 (%)

[0033] It can be seen from Table 1 that the content of impurity elements in the nickel-cerium master alloy prepared in this embodiment is relatively low, indicating that the preparation method of the present invention can reduce the impurity content of the nickel-cerium master alloy and improve the purity of the nickel-cerium master alloy.

[0034] Example 2 The preparation method of this embodiment comprises the following steps: Step 1: Dry cerium oxide powder, nickelous oxide powder, aluminum powder, calcium oxide powder and calcium fluoride powder at 100°C for 5 hours, then place in a V-type mixer for mixing for 50 minutes, and compact to obtain a blank; the blank is composed of the following components by mass: 13 parts of cerium oxide, 64 parts of nickelous oxide, 12 parts of aluminum powder, 3 parts of calcium oxide, and 5 parts of calcium fluoride; the speed of the V-type mixer is 35r / min; Step 2: placing the blank obtained in step 1 in a tungsten crucible of an induction heating furnace for argon purge at a flow rate of 3L / min, adjusting the power of the induction heating furnace to 40kW for preheating for 2min, and then adjusting the power to 90kW, raising the heating temperature to 1400°C-1500°C for heating, and obtaining a melt after the blank is completely melted. After the melt is kept warm to maintain the molten state for 15min, the heating function of the induction heating furnace is turned off, and the argon is turned off after the melt solidifies and the temperature is lower than 800°C. After air cooling, the upper slag is separated, and finishing, screening and inspection are performed to obtain a nickel-cerium intermediate alloy; the argon quality purity is 99.99%.

[0035] The element content of the nickel-cerium master alloy prepared in this example was tested, and the test results are shown in Table 2.

[0036] Table 2 Element mass content of the nickel-cerium master alloy prepared in Example 2 (%)

[0037] It can be seen from Table 2 that the content of impurity elements in the nickel-cerium master alloy prepared in this embodiment is relatively low, indicating that the preparation method of the present invention can reduce the impurity content of the nickel-cerium master alloy and improve the purity of the nickel-cerium master alloy.

[0038] Example 3 The preparation method of this embodiment comprises the following steps: Step 1: Dry cerium oxide powder, nickelous oxide powder, aluminum powder, calcium oxide powder and calcium fluoride powder at 120°C for 6 hours, then place in a V-type mixer for mixing for 60 minutes, and compact to obtain a blank; the blank is composed of the following components by mass: 16 parts of cerium oxide, 65 parts of nickelous oxide, 13 parts of aluminum powder, 2 parts of calcium oxide, and 2 parts of calcium fluoride; the speed of the V-type mixer is 40r / min; Step 2: placing the blank obtained in step 1 in a tungsten crucible of an induction heating furnace for argon purge at a flow rate of 4 L / min, adjusting the power of the induction heating furnace to 50 kW for preheating for 2 minutes, and then adjusting the power to 100 kW, raising the heating temperature to 1400°C-1500°C for heating, and obtaining a melt after the blank is completely melted. After the melt is kept warm to maintain the molten state for 20 minutes, the heating function of the induction heating furnace is turned off, and the argon is turned off after the melt solidifies and the temperature is lower than 800°C. After air cooling, the upper slag is separated, and finishing, screening and inspection are performed to obtain a nickel-cerium intermediate alloy; the argon quality purity is 99.99%.

[0039] The element content of the nickel-cerium master alloy prepared in this example was tested, and the test results are shown in Table 3.

[0040] Table 3 Element mass content of the nickel-cerium master alloy prepared in Example 3 (%)

[0041] It can be seen from Table 3 that the content of impurity elements in the nickel-cerium master alloy prepared in this embodiment is relatively low, indicating that the preparation method of the present invention can reduce the impurity content of the nickel-cerium master alloy and improve the purity of the nickel-cerium master alloy.

[0042] Example 4 The preparation method of this embodiment comprises the following steps: Step 1: Dry cerium oxide powder, nickelous oxide powder, aluminum powder, calcium oxide powder and calcium fluoride powder at 160°C for 4 hours, then place in a V-type mixer for mixing for 30 minutes, and compact to obtain a blank; the blank is composed of the following components by mass: 11 parts of cerium oxide, 70 parts of nickelous oxide, 14 parts of aluminum powder, 2.5 parts of calcium oxide, and 6 parts of calcium fluoride; the speed of the V-type mixer is 30r / min; Step 2: placing the blank obtained in step 1 in a tungsten crucible of an induction heating furnace for purging with argon at a flow rate of 2L / min, adjusting the power of the induction heating furnace to 30kW for preheating for 2min, and then adjusting the power to 80kW, raising the heating temperature to 1400°C-1500°C for heating, and obtaining a melt after the blank is completely melted. The melt is kept warm so that the molten state is maintained for 10min, and then the heating function of the induction heating furnace is turned off. After the melt solidifies and the temperature is lower than 800°C, the argon is turned off, and the upper slag is separated after air cooling, and finishing, screening and inspection are performed to obtain a nickel-cerium intermediate alloy; the argon quality purity is 99.99%.

[0043] The element content of the nickel-cerium master alloy prepared in this example was tested, and the test results are shown in Table 4.

[0044] Table 4 Element mass content of the nickel-cerium master alloy prepared in Example 4 (%)

[0045] It can be seen from Table 4 that the content of impurity elements in the nickel-cerium master alloy prepared in this embodiment is relatively low, indicating that the preparation method of the present invention can reduce the impurity content of the nickel-cerium master alloy and improve the purity of the nickel-cerium master alloy.

[0046] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a nickel-cerium master alloy for high-temperature alloys, characterized in that: The preparation method comprises the following steps: Step 1: drying cerium oxide powder, nickelous oxide powder, aluminum powder, calcium oxide powder and calcium fluoride powder, and then mixing and compacting to obtain a blank; Step 2: placing the blank obtained in step 1 in an induction heating furnace for argon purging, preheating, heating to 1400° C. to 1500° C. and keeping warm to obtain a nickel-cerium master alloy.

2. The method for preparing a nickel-cerium master alloy for high-temperature alloy according to claim 1, characterized in that: The mass purity of the cerium oxide powder in step 1 is more than 94%, and the particle size is 80 mesh; the mass content of nickel element in the nickelous oxide powder is not less than 75%, and the particle size is 100 mesh; the mass purity of the aluminum powder is more than 98%, and the particle size is 30 mesh; the mass purity of the calcium oxide powder is more than 99%, and the particle size is 80 mesh; the mass purity of the calcium fluoride powder is more than 99.5%, and the particle size is 80 mesh.

3. The method for preparing a nickel-cerium master alloy for high-temperature alloy according to claim 1, characterized in that: The drying temperature in step 1 is 70° C. to 160° C., and the drying time is 4 h to 6 h.

4. The method for preparing a nickel-cerium master alloy for high-temperature alloy according to claim 1, characterized in that: The blank in step 1 is composed of the following components in parts by mass: 11-16 parts of cerium oxide, 64-70 parts of nickelous oxide, 11-14 parts of aluminum powder, 2-3 parts of calcium oxide, and 2-6 parts of calcium fluoride.

5. The method for preparing a nickel-cerium master alloy for high-temperature alloy according to claim 1, characterized in that: The mixing speed in step 1 is 30 r / min to 40 r / min, and the mixing time is 30 min to 60 min.

6. The method for preparing a nickel-cerium master alloy for high-temperature alloy according to claim 1, characterized in that: In step 2, a tungsten crucible is used in the induction heating furnace, and the flow rate of the argon purge is 2L / min~4L / min.

7. The method for preparing a nickel-cerium master alloy for high-temperature alloy according to claim 1, characterized in that: The preheating process in step 2 is: adjust the power of the induction heating furnace to 30kW~50kW for preheating for more than 2 minutes.

8. The method for preparing a nickel-cerium master alloy for high-temperature alloy according to claim 1, characterized in that: The heating process in step 2 is: the power of the heating furnace is increased to 80 kW to 100 kW for melting until the blank is completely melted, and the insulation time is 10 min to 20 min.

9. The method for preparing a nickel-cerium master alloy for high-temperature alloy according to claim 1, characterized in that: The nickel-cerium master alloy in step 2 is composed of the following components by mass fraction: Composition: Ce 25%~35%, Cu not more than 0.01%, Fe not more than 0.01%, C not more than 0.05%, N not more than 0.01%, O not more than 0.01%, and the balance is Ni.

10. A nickel-cerium master alloy for high temperature alloys, characterized in that: Obtained by the preparation method described in any one of claims 1 to 9.

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