Process for preparing rare earth polishing powder through temperature control precipitation method

Abstract

The invention discloses a process for preparing rare earth polishing powder by a temperature control precipitation method. The process comprises the following steps: step 1, preparing a solvent; step 2, temperature-controlled precipitation reaction; step 3, cleaning; step 4, crushing; and step 5, roasting. According to the process, a temperature-controlled precipitation method is adopted, the initial temperature and the temperature rising rate are controlled in the precipitation reaction process, particle growth can be controlled, particle aggregation can be inhibited, and the rare earth polishing powder with good uniformity and uniform particle size distribution can be obtained after crushing and roasting; the method does not need aging treatment after precipitation reaction to adjust the apparent morphology of the precursor, can effectively shorten the preparation process flow, and is suitable for the technical field of micro-nano powder synthesis.

Description

Technical Field

[0001] The invention belongs to the technical field of micro-nano powder synthesis, and in particular relates to a process for preparing rare earth polishing powder by a temperature-controlled precipitation method. Background Art

[0002] Chemical mechanical polishing (CMP) is an industrial technology for ultra-precision machining. It is widely used in precision optics, aerospace, and information technology because it can perfectly balance global flatness, material surface defects, and reliability. However, with the continuous improvement of product standards in the field of high-precision polishing, the requirements for the uniformity of rare earth polishing powder particles, especially the avoidance of large particles, are increasing year by year, becoming an important factor affecting the quality of polishing powder.

[0003] The methods for preparing rare earth polishing powder that are easy to implement in industry mainly include precipitation method and hydrothermal method. Among them, the hydrothermal method has a better morphology for preparing polishing powder, and can obtain nearly spherical particles of different sizes through process control, but it requires a high temperature and high pressure environment during preparation, with high production cost and low efficiency. In comparison, the precipitation method, as the most widely used method for preparing polishing powder, has the advantages of high production efficiency, low process cost, and simple equipment requirements.

[0004] For example, the Chinese invention patent "An ultrafine, spheroidized rare earth polishing powder and its preparation process" (publication number CN101284983B) uses ammonia precipitation to prepare ultrafine, spheroidized rare earth polishing powder, which needs to be aged at high temperature after precipitation, and then crushed and screened by ball milling or air flow milling to obtain rare earth polishing powder. The Chinese invention patent "A method for preparing micron cerium oxide with a large specific surface area" (publication number CN106277020A) adds oxalic acid or sodium hydroxide and anionic surfactants to a rare earth salt solution, obtains a precursor after precipitation and aging, and then adds a coupling agent and burns to obtain cerium oxide. However, the above precipitation method uses a fixed temperature insulation reaction, and it is necessary to age after the precipitation reaction to optimize the product morphology. There are problems such as a long precipitation + aging process and difficulty in controlling the product morphology. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a process for preparing rare earth polishing powder by temperature-controlled precipitation. The method controls the temperature rise during the precipitation reaction, and does not require aging. After crushing and roasting, polishing powder with good uniformity and narrow particle size distribution can be obtained, which solves the problems of long preparation process and difficult product morphology control of rare earth polishing powder in the prior art.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a process for preparing rare earth polishing powder by temperature-controlled precipitation method, characterized in that the process comprises the following steps:

[0007] Step 1, solvent preparation: mix the rare earth salt, dispersant and water evenly to obtain solvent A; mix the alkaline precipitant, oxidant and water evenly to obtain solvent B;

[0008] Step 2: Temperature-controlled precipitation reaction: Solvent A and solvent B obtained in step 1 are mixed in a heated environment, and a precipitation reaction is performed to obtain a precursor;

[0009] Step 3, cleaning: adding the precursor obtained in step 2 into deionized water for ultrasonic cleaning and centrifugation;

[0010] Step 4: crushing: drying and crushing the precursor after centrifugation in step 3 to obtain precursor powder;

[0011] Step 5: Calcination: Calcinate the precursor powder obtained in step 4 to obtain rare earth polishing powder.

[0012] The present invention increases the valence state of the rare earth element by adding an oxidant to the solvent B, and transforms the precipitation product into a rare earth oxide by combining the temperature-raising precipitation reaction, thereby achieving preliminary crystallization. Subsequent calcination can strengthen the crystallization and improve the crystallinity of the rare earth polishing powder. For example, when the rare earth salt includes a Ce salt, the oxidant oxidizes the rare earth into Ce. 4+ The precipitation product is transformed into CeO2 to achieve initial crystallization, and the crystallization is strengthened by calcination. However, the product precipitated at a fixed temperature in the prior art is generally an amorphous precursor, which is transformed into basic carbonates such as Ce2(CO3)3·8H2O, [Nd, La, Ca][CO3][OH][H2O] after aging. The morphology and particle size uniformity of the product after calcination are poor.

[0013] The above-mentioned process for preparing rare earth polishing powder by a temperature-controlled precipitation method is characterized in that the concentration of the rare earth salt in the solvent A in step one is 0.1 mol / L to 1 mol / L, and the rare earth salt is one or more of water-soluble rare earth salts and hydrates thereof.

[0014] The above-mentioned process for preparing rare earth polishing powder by temperature-controlled precipitation method is characterized in that the mass concentration of the dispersant in the solvent A in step one is 0.1% to 4%, and the dispersant is one of polyethylene glycol, polyvinyl pyrrolidone and hydroxypropyl cellulose.

[0015] The above-mentioned process for preparing rare earth polishing powder by a temperature-controlled precipitation method is characterized in that the concentration of the alkaline precipitant in the solvent B in step 1 is 1.5 mol / L to 5.5 mol / L, and the alkaline precipitant is one or more of ammonium bicarbonate, ammonia water, sodium bicarbonate and urea.

[0016] The above-mentioned process for preparing rare earth polishing powder by a temperature-controlled precipitation method is characterized in that the concentration of the oxidant in the solvent B in step 1 is 0.1 mol / L to 2 mol / L, and the oxidant is hydrogen peroxide.

[0017] The above-mentioned process for preparing rare earth polishing powder by a temperature-controlled precipitation method is characterized in that the mixing process described in step 2 is: using a micro-injection pump or a peristaltic pump to dropwise add solvent B into solvent A at a flow rate of 1 mL / min to 20 mL / min; stirring is performed during the mixing process; the temperature rising environment system is: first controlling the initial temperature below 40°C, then heating to 65°C to 95°C at a rate of 0.5°C / min to 2°C / min and then keeping warm, and the temperature difference between the keeping temperature and the initial temperature is not less than 45°C; the precipitation reaction time does not exceed 90 minutes.

[0018] The present invention controls the uniform dripping speed of solvent B by using a microinjection pump or a peristaltic pump, controls the precipitation reaction time within 90 minutes according to the amount of reactants and the dripping speed, and can avoid excessively large product particles, wherein the dripping time of solvent B is the precipitation reaction time; controls the temperature rise rate and the temperature difference between the beginning and the end of the precipitation reaction during the dripping of solvent B, and is used to control the supersaturation and precipitation coefficient of the mixture of solvent A and solvent B, thereby increasing crystal nucleation, inhibiting the growth of product particles, and improving product uniformity; combined with controlling the precipitation reaction time and temperature, the particle size can be controlled to be below 1 μm, and the generation of excessively large product particles can be avoided.

[0019] The above-mentioned process for preparing rare earth polishing powder by temperature-controlled precipitation method is characterized in that the precursor in step three is ultrasonically cleaned and cooled to below 50° C. before centrifugation.

[0020] The present invention can maintain the product morphology by cooling the precursor before ultrasonic cleaning and centrifugation, and avoid the hot solution directly entering the liquid with a lower temperature and rapidly cooling to generate amorphous precipitation.

[0021] The above-mentioned process for preparing rare earth polishing powder by temperature-controlled precipitation method is characterized in that the crushing in step 4 is drying grinding or freeze-drying treatment.

[0022] The present invention disperses the adhered agglomerates in the precipitation product by crushing. The precipitation product does not need to be adjusted for the morphology for a second time and can be simply crushed by drying, grinding or freeze-drying. The freeze-drying process is performed by a freeze dryer, which can simultaneously realize the drying and crushing of the wet precipitate, and has better uniformity.

[0023] The above-mentioned process for preparing rare earth polishing powder by temperature-controlled precipitation method is characterized in that the calcination temperature in step five is 300°C to 1000°C.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. The present invention adopts a temperature-controlled precipitation method to control the temperature rise during the precipitation reaction, thereby controlling particle growth and inhibiting particle agglomeration. After crushing and roasting, polishing powder with good uniformity and uniform particle size distribution can be obtained.

[0026] 2. The preparation process of the present invention does not require aging after the precipitation reaction to adjust the surface morphology of the precursor, which can effectively shorten the preparation process of the rare earth polishing powder, thereby reducing energy consumption and improving production efficiency.

[0027] 3. The present invention adds an oxidant to the solvent B to increase the valence state of the rare earth element, transform the precipitation product into a rare earth oxide, and achieve preliminary crystallization. Subsequent calcination can strengthen the crystallization and improve the crystallinity and particle size uniformity of the rare earth polishing powder. This avoids the use of a precipitation + aging process in the prior art, in which after precipitation at a fixed temperature, the morphology is controlled by adjusting the aging temperature and time, resulting in excessive grain growth, which is not conducive to controlling the morphology and particle size uniformity of the rare earth polishing powder.

[0028] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a graph showing the XRD test results of the rare earth polishing powder obtained in Example 1 of the present invention.

[0030] Figure 2 This is a scanning electron microscope image of the rare earth polishing powder obtained in Example 1 of the present invention.

[0031] Figure 3 This is a scanning electron microscope image of the rare earth polishing powder obtained in Comparative Example 1 of the present invention.

[0032] Figure 4 This is a scanning electron microscope image of the rare earth polishing powder obtained in Example 2 of the present invention. DETAILED DESCRIPTION

[0033] Example 1

[0034] The process of this embodiment includes the following steps:

[0035] Step 1, solvent preparation: 7 g of cerium nitrate hexahydrate, 3 g of lanthanum nitrate hexahydrate and 1 g of polyethylene glycol were mixed with 50 mL of deionized water to obtain solvent A; 4 g of ammonium bicarbonate, 2 mL of ammonia water, 5 mL of hydrogen peroxide and 50 mL of deionized water were mixed to obtain solvent B;

[0036] Step 2, temperature-controlled precipitation reaction: preheat the solvent A obtained in step 1 in a water bath at 40°C, and use a microinjection pump to drop solvent B into solvent A at a flow rate of 1 mL / min, and during the dropwise addition, the water bath is heated to 85°C at a rate of 1°C / min and then kept warm to obtain a precursor; during the temperature-controlled precipitation reaction, stirring is performed at a speed of 600 r / min, and the precipitation reaction time is 50 min;

[0037] Step 3, cleaning: cooling the precursor obtained in step 2 to below 50° C., and then adding it to deionized water for ultrasonic cleaning and centrifugation;

[0038] Step 4, crushing: placing the precursor after centrifugation in step 3 in an oven at 60°C and grinding to obtain precursor powder;

[0039] Step 5: Calcination: The precursor powder obtained in step 4 is placed in a muffle furnace and calcined at 600° C. to obtain rare earth polishing powder.

[0040] The rare earth polishing powder obtained in this embodiment was subjected to XRD analysis, and the results are as follows: Figure 1 As shown in FIG. 1 , the main phase of the rare earth polishing powder is (Ce, La)O2; the rare earth polishing powder obtained in this embodiment is subjected to microscopic analysis, as shown in FIG. Figure 2 As shown, the rare earth polishing powder is submicron particles with uniform particle size distribution, and no large particle agglomeration occurs.

[0041] The rare earth polishing powder obtained in this embodiment is used to prepare a polishing liquid containing 0.5% by mass of rare earth polishing powder. A polishing test is performed on K9 glass, and the surface removal rate (MRR) of the polishing liquid is measured to be 500nm / min, and the surface roughness (Ra) of the polishing liquid after polishing is 0.48nm.

[0042] Comparative Example 1

[0043] The difference between this comparative example and Example 1 is that the ambient temperature of the temperature-controlled precipitation reaction in step 2 is a constant temperature of 75°C.

[0044] The rare earth polishing powder obtained in this comparative example was subjected to microscopic analysis. Figure 3 As shown, the rare earth polishing powder has a distinct flaky morphology and varies in size. Some particles have a particle size greater than 10 μm and are not suitable for direct use as polishing powder. This indicates that in Example 1, by carrying out a precipitation reaction under a rising temperature environment, the particle size of the rare earth polishing powder can be effectively reduced, the morphology can be optimized, and the uniformity of the particle size of the rare earth polishing powder can be improved.

[0045] Example 2

[0046] The process of this embodiment includes the following steps:

[0047] Step 1, solvent preparation: 13g of cerium nitrate hexahydrate, 3g of lanthanum nitrate hexahydrate and 1.5g of polyethylene glycol were mixed with 50mL of deionized water to obtain solvent A; 6g of ammonium bicarbonate, 3ml of ammonia water, 6mL of hydrogen peroxide and 50mL of deionized water were mixed to obtain solvent B;

[0048] Step 2, temperature-controlled precipitation reaction: preheat the solvent A obtained in step 1 in a water bath at 20°C, and use a microinjection pump to drop solvent B into solvent A at a flow rate of 1 mL / min, and during the dropping process, the water bath is heated to 65°C at a rate of 1°C / min and then kept warm to obtain a precursor; during the temperature-controlled precipitation reaction, stirring is performed at a speed of 1000 r / min, and the precipitation reaction time is 50 min;

[0049] Step 3, cleaning: cooling the precursor obtained in step 2 to below 50° C., and then adding it to deionized water for ultrasonic cleaning and centrifugation;

[0050] Step 4, crushing: freeze-drying the precursor after centrifugation in step 3 using a freeze dryer to obtain a precursor powder;

[0051] Step 5: Calcination: The precursor powder obtained in step 4 is placed in a muffle furnace and calcined at 700° C. to obtain rare earth polishing powder.

[0052] The rare earth polishing powder obtained in this embodiment was subjected to microscopic analysis. Figure 4 As shown, the rare earth polishing powder is a submicron particle with uniform particle size distribution. Compared with Example 1, the rare earth polishing powder has higher uniformity. The freeze-drying technology used on the surface is beneficial to improving the uniformity of the particle size of the rare earth polishing powder.

[0053] The rare earth polishing powder obtained in this embodiment is used to prepare a polishing liquid containing 0.5% by mass of rare earth polishing powder. A polishing test is performed on K9 glass, and the surface removal rate (MRR) of the polishing liquid is measured to be 556nm / min, and the surface roughness (Ra) of the polishing liquid after polishing is 0.34nm.

[0054] Example 3

[0055] The process of this embodiment includes the following steps:

[0056] Step 1, solvent preparation: 5g of cerium nitrate hexahydrate, 1g of lanthanum nitrate hexahydrate and 1g of polyvinyl pyrrolidone were mixed with 50mL of deionized water to obtain solvent A; 4g of sodium bicarbonate, 1ml of ammonia water, 3mL of hydrogen peroxide and 50mL of deionized water were mixed to obtain solvent B;

[0057] Step 2, temperature-controlled precipitation reaction: preheat the solvent A obtained in step 1 in a water bath at 30°C, and use a microinjection pump to drop solvent B into solvent A at a flow rate of 1 mL / min, and during the dropping process, the water bath is heated to 95°C at a rate of 2°C / min and then kept warm to obtain a precursor; during the temperature-controlled precipitation reaction, stirring is performed at a speed of 600 r / min, and the precipitation reaction time is 50 min;

[0058] Step 3, cleaning: cooling the precursor obtained in step 2 to below 50° C., and then adding it to deionized water for ultrasonic cleaning and centrifugation;

[0059] Step 4, crushing: placing the precursor after centrifugation in step 3 in an oven at 60°C and grinding to obtain precursor powder;

[0060] Step 5: Calcination: The precursor powder obtained in step 4 is placed in a muffle furnace and calcined at 600° C. to obtain rare earth polishing powder.

[0061] The rare earth polishing powder obtained in this embodiment is used to prepare a polishing liquid containing 0.5% by mass of rare earth polishing powder. A polishing test is performed on K9 glass, and the surface removal rate (MRR) of the polishing liquid is measured to be 621nm / min, and the surface roughness (Ra) of the polishing liquid after polishing is 0.52nm.

[0062] Example 4

[0063] The process of this embodiment includes the following steps:

[0064] Step 1, solvent preparation: 76g of cerium nitrate hexahydrate, 35g of lanthanum nitrate hexahydrate and 15g of polyvinyl pyrrolidone were mixed with 500mL of deionized water to obtain solvent A; 80g of ammonium bicarbonate, 30ml of ammonia water, 45mL of hydrogen peroxide and deionized water were mixed into 500mL to obtain solvent B;

[0065] Step 2, temperature-controlled precipitation reaction: preheat the solvent A obtained in step 1 in a water bath at 40°C, use a peristaltic pump to dropwise add solvent B into solvent A at a flow rate of 5.5 mL / min, and during the dropping process, the water bath is heated to 85°C at a rate of 0.5°C / min and then kept warm to obtain a precursor; during the temperature-controlled precipitation reaction, stirring is performed at a speed of 1000 r / min; the reaction time is 90 min.

[0066] Step 3, cleaning: cooling the precursor obtained in step 2 to below 50° C., and then adding it to deionized water for ultrasonic cleaning and centrifugation;

[0067] Step 4, crushing: placing the precursor after centrifugation in step 3 in an oven at 60°C and grinding to obtain precursor powder;

[0068] Step 5: Calcination: The precursor powder obtained in step 4 is placed in a muffle furnace and calcined at 800° C. to obtain rare earth polishing powder.

[0069] The rare earth polishing powder obtained in this embodiment is used to prepare a polishing liquid containing 0.5% by mass of rare earth polishing powder. A polishing test is performed on K9 glass, and the surface removal rate (MRR) of the polishing liquid is measured to be 628nm / min, and the surface roughness (Ra) of the polishing liquid after polishing is 0.74nm.

[0070] Example 5

[0071] The process of this embodiment includes the following steps:

[0072] Step 1, solvent preparation: 200g of cerium nitrate hexahydrate, 100g of lanthanum nitrate hexahydrate and 30g of polyvinyl pyrrolidone are mixed with 1500mL of deionized water to obtain solvent A; 200g of ammonium bicarbonate, 30ml of ammonia water, 80mL of hydrogen peroxide and deionized water are mixed to make 1500mL to obtain solvent B;

[0073] Step 2, temperature-controlled precipitation reaction: preheat the solvent A obtained in step 1 in a water bath at 40°C, use a peristaltic pump to dropwise add solvent B into solvent A at a flow rate of 20 mL / min, and during the dropping process, the water bath is heated to 85°C at a rate of 1°C / min and then kept warm to obtain a precursor; during the temperature-controlled precipitation reaction, stirring is performed at a speed of 1000 r / min; the reaction time is 75 min.

[0074] Step 3, cleaning: cooling the precursor obtained in step 2 to below 50° C., and then adding it to deionized water for ultrasonic cleaning and centrifugation;

[0075] Step 4, crushing: placing the precursor after centrifugation in step 3 in an oven at 60°C and grinding to obtain precursor powder;

[0076] Step 5: Calcination: Place the precursor powder obtained in step 4 in a muffle furnace and calcine it at 1000° C. to obtain rare earth polishing powder.

[0077] The rare earth polishing powder obtained in this embodiment is used to prepare a polishing liquid containing 0.5% by mass of rare earth polishing powder. A polishing test is performed on K9 glass, and the surface removal rate (MRR) of the polishing liquid is measured to be 778nm / min, and the surface roughness (Ra) of the polishing liquid after polishing is 1.02nm.

[0078] Example 6

[0079] The process of this embodiment includes the following steps:

[0080] Step 1, solvent preparation: 2g of cerium nitrate hexahydrate and 0.05g of polyvinyl pyrrolidone were mixed with 50mL of deionized water to obtain solvent A; 4g of ammonium bicarbonate, 1ml of ammonia water, 1mL of hydrogen peroxide and deionized water were mixed into 50mL to obtain solvent B;

[0081] Step 2, temperature-controlled precipitation reaction: preheat the solvent A obtained in step 1 in a water bath at 40°C, and use a microinjection pump to drop solvent B into solvent A at a flow rate of 1 mL / min, and during the dropwise addition, the water bath is heated to 85°C at a rate of 1°C / min and then kept warm to obtain a precursor; during the temperature-controlled precipitation reaction, stirring is performed at a speed of 600 r / min, and the precipitation reaction time is 50 min;

[0082] Step 3, cleaning: cooling the precursor obtained in step 2 to below 50° C., and then adding it to deionized water for ultrasonic cleaning and centrifugation;

[0083] Step 4, crushing: placing the precursor after centrifugation in step 3 in an oven at 60°C and grinding to obtain precursor powder;

[0084] Step 5: Calcination: Place the precursor powder obtained in step 4 in a muffle furnace and calcine it at 300° C. to obtain rare earth polishing powder.

[0085] The sample quantity obtained was small and no polishing test was performed.

[0086] Example 7

[0087] The process of this embodiment includes the following steps:

[0088] Step 1, solvent preparation: 11g of cerium nitrate hexahydrate, 10g of lanthanum nitrate hexahydrate and 2g of polyvinyl pyrrolidone were mixed with 50mL of deionized water to obtain solvent A; 16.5g of urea, 3ml of ammonia water, 10mL of hydrogen peroxide and deionized water were mixed into 50mL to obtain solvent B;

[0089] Step 2, temperature-controlled precipitation reaction: preheat the solvent A obtained in step 1 in a water bath at 40°C, and use a microinjection pump to drop solvent B into solvent A at a flow rate of 1 mL / min, and during the dropwise addition, the water bath is heated to 85°C at a rate of 1°C / min and then kept warm to obtain a precursor; during the temperature-controlled precipitation reaction, stirring is performed at a speed of 600 r / min, and the precipitation reaction time is 50 min;

[0090] Step 3, cleaning: cooling the precursor obtained in step 2 to below 50° C., and then adding it to deionized water for ultrasonic cleaning and centrifugation;

[0091] Step 4, crushing: placing the precursor after centrifugation in step 3 in an oven at 60°C and grinding to obtain precursor powder;

[0092] Step 5: Calcination: The precursor powder obtained in step 4 is placed in a muffle furnace and calcined at 700° C. to obtain rare earth polishing powder.

[0093] The rare earth polishing powder obtained in this embodiment is used to prepare a polishing liquid containing 0.5% by mass of rare earth polishing powder. A polishing test is performed on K9 glass, and the surface removal rate (MRR) of the polishing liquid is measured to be 651nm / min, and the surface roughness (Ra) of the polishing liquid after polishing is 0.63nm.

[0094] 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 process for preparing rare earth polishing powder by temperature-controlled precipitation method, characterized in that: The process includes the following steps: Step 1, solvent preparation: mix the rare earth salt, dispersant and water evenly to obtain solvent A; mix the alkaline precipitant, oxidant and water evenly to obtain solvent B; Step 2: Temperature-controlled precipitation reaction: Solvent A and solvent B obtained in step 1 are mixed in a heated environment, and a precipitation reaction is performed to obtain a precursor; Step 3, cleaning: adding the precursor obtained in step 2 into deionized water for ultrasonic cleaning and centrifugation; Step 4: crushing: drying and crushing the precursor after centrifugation in step 3 to obtain precursor powder; Step 5: Calcination: Calcinate the precursor powder obtained in step 4 to obtain rare earth polishing powder.

2. The process for preparing rare earth polishing powder by a temperature-controlled precipitation method according to claim 1, characterized in that: The concentration of the rare earth salt in the solvent A in step 1 is 0.1 mol / L to 1 mol / L, and the rare earth salt is one or more of water-soluble rare earth salts and hydrates thereof.

3. The process for preparing rare earth polishing powder by a temperature-controlled precipitation method according to claim 1, characterized in that: The mass concentration of the dispersant in the solvent A in step 1 is 0.1% to 4%, and the dispersant is one of polyethylene glycol, polyvinyl pyrrolidone and hydroxypropyl cellulose.

4. The process for preparing rare earth polishing powder by a temperature-controlled precipitation method according to claim 1, characterized in that: The concentration of the alkaline precipitant in the solvent B in step 1 is 1.5 mol / L to 5.5 mol / L, and the alkaline precipitant is one or more of ammonium bicarbonate, ammonia water, sodium bicarbonate and urea.

5. The process for preparing rare earth polishing powder by a temperature-controlled precipitation method according to claim 1, characterized in that: The concentration of the oxidant in the solvent B in step 1 is 0.1 mol / L to 2 mol / L, and the oxidant is hydrogen peroxide.

6. The process for preparing rare earth polishing powder by a temperature-controlled precipitation method according to claim 1, characterized in that: The mixing process in step 2 is: using a microinjection pump or a peristaltic pump to dropwise add solvent B into solvent A at a flow rate of 1 mL / min to 20 mL / min; stirring is performed during the mixing process; the temperature rise environment system is: first controlling the initial temperature below 40°C, then heating to 65°C to 95°C at a rate of 0.5°C / min to 2°C / min and then keeping warm, and the temperature difference between the keeping temperature and the initial temperature is not less than 45°C; the precipitation reaction time does not exceed 90 minutes.

7. The process for preparing rare earth polishing powder by a temperature-controlled precipitation method according to claim 1, characterized in that: In step 3, the precursor is ultrasonically cleaned and cooled to below 50° C. before centrifugation.

8. The process for preparing rare earth polishing powder by a temperature-controlled precipitation method according to claim 1, characterized in that: The crushing in step 4 is drying and grinding or freeze-drying.

9. The process for preparing rare earth polishing powder by a temperature-controlled precipitation method according to claim 1, characterized in that: The calcination temperature in step 5 is 300°C to 1000°C.

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