Rare earth polishing powder as well as preparation method and application thereof

Abstract

The invention discloses rare earth polishing powder as well as a preparation method and application thereof. The preparation method of the rare earth polishing powder comprises the following steps: 1) roasting praseodymium-containing cerium carbonate in an up-down simultaneous heating manner to obtain a roasted product; wherein in the praseodymium-containing cerium carbonate, the content of Pr6O11 / TREO is 0.1 to 2 weight percent, and the content of CeO2 / TREO is 90 to 99.9 weight percent; the heating temperature above the praseodymium-containing cerium carbonate is 950-1200 DEG C, and the heating temperature below the praseodymium-containing cerium carbonate is 900-1100 DEG C; (2) the roasted product is subjected to airflow crushing, and crushed coarse powder is obtained; and (3) screening the crushed coarse powder under a screen of 150-350 meshes to prepare the rare earth polishing powder. The polishing corrosion amount of the prepared rare earth polishing powder to a polished part is at least 0.15 mg / cm < 2 >. Min, the scratch rate is at most 8%, and the rare earth polishing powder has excellent polishing performance.

Description

Technical Field

[0001] The invention relates to rare earth polishing powder and a preparation method and application thereof. Background Art

[0002] In recent years, my country's crystal processing industry has developed rapidly, and its products are sold well at home and abroad. However, the proportion of high-quality products is not large, which not only affects the reputation of crystal jewelry, but also wastes crystal raw materials. The reason is that most of the so-called inferior products are caused by the lack of strict control of polishing quality. Many polished facets have obvious scratches, sand holes, and even unevenness or unfinished polishing, which seriously affects the optical effect of crystal, which already has very low dispersion. The reasons for these problems are related to the polishing time, and more importantly, they are directly related to the selected polishing materials.

[0003] Polishing is the last step in crystal processing, the most time-consuming step, and the most critical step. Generally speaking, the polishing discs used for polishing faceted crystal jewelry in China are water-based chromium oxide, cerium oxide, or iron oxide with tin alloy polishing discs, organic glass discs, or foam discs.

[0004] CN102965026A discloses a rare earth polishing powder and a preparation method thereof. The rare earth polishing powder is a homogeneous solid solution composed of one or more of cerium oxide, lanthanum oxide and praseodymium oxide, and the crystal form is a cubic phase rare earth oxide. The polishing powder is obtained by ball milling, drying and roasting rare earth carbonate in an alkaline solution. The praseodymium-containing carbonate used to prepare the rare earth polishing powder is lanthanum cerium praseodymium carbonate, and the preparation method requires slurrying the rare earth carbonate with water and adding alkali for pretreatment.

[0005] CN103130262A discloses a method for preparing a low-polish cerium oxide polishing powder. The method first adds a cerium nitrate solution into a reactor, adds a certain amount of cerium oxalate under stirring conditions, and then heats the material in the reactor to keep the material temperature at 45-60°C, adds an oxalic acid solution at this temperature, and continues stirring for 20-45 minutes after the oxalic acid solution is added, then stops stirring, and allows the cerium oxalate precursor to precipitate for 15-30 minutes, washes with water until the pH value is 6.5-7.0, and then sifts and filters the precipitate to form a loose granular cerium oxalate material; then the cerium oxalate material after drying and filtering is kept warm, and after cooling, it is sieved and impurities are removed to obtain a cerium oxide polishing powder with an average particle size of 7-10 μm and a maximum particle size controlled within 30 μm. The method uses oxalic acid precipitated high-purity cerium nitrate as a precursor to prepare cerium oxide polishing powder, and the particle size of the polishing powder is too large. And the method does not detect the polishing amount of rare earth polishing powder.

[0006] CN103555206A discloses a rare earth polishing powder and a preparation method thereof. The rare earth polishing powder is composed of rare earth oxide and aluminum silicate; wherein the rare earth oxide is lanthanum cerium oxide or lanthanum cerium praseodymium oxide; the mass content of the rare earth oxide in the rare earth polishing powder is 66-85%; the rest is aluminum silicate. The rare earth polishing powder is prepared by slurrying rare earth carbonate and aluminosilicate, ball milling, drying, roasting and crushing. The rare earth polishing powder contains aluminum silicate and the preparation method requires making a slurry of rare earth carbonate and aluminosilicate. And the polishing amount of the rare earth polishing powder prepared by the method is low. The addition of aluminum silicate will cause irreparable scratches, pits and other damages to the surface of the crystal glass, seriously affecting the light scattering effect of the crystal glass.

[0007] CN117655937A discloses a rare earth polishing disc for polishing crystal glass. The rare earth polishing disc comprises a polishing layer, which is prepared from a rare earth polishing liquid, which comprises the following raw materials in mass percentage: 50.0-60.0% polishing powder, 15.0-25.0% epoxy resin glue, 2-7% dispersant, 1.0-2% defoamer, and the balance is water. The polishing powder is an intermediate raw material for preparing the polishing disc and is not directly used for polishing. The polishing powder is directly mixed by 96-99.55wt% cerium oxide, 0.4-4wt% praseodymium oxide, and 0-3.5wt% non-rare earth compound. Summary of the invention

[0008] In view of this, an object of the present invention is to provide a method for preparing rare earth polishing powder, wherein the polishing amount of the rare earth polishing powder prepared by the method is at least 0.15 mg / cm 2 ·min, having excellent grinding force. Another object of the present invention is to provide a rare earth polishing powder prepared by the above preparation method. Still another object of the present invention is to provide a use of the above rare earth polishing powder.

[0009] The present invention adopts the following technical solutions to achieve the above-mentioned purpose.

[0010] On the one hand, the method for preparing rare earth polishing powder provided by the present invention comprises the following steps:

[0011] 1. A method for preparing rare earth polishing powder, comprising the following steps:

[0012] 1) calcining cerium carbonate containing praseodymium by heating it up and down simultaneously to obtain a calcined product; wherein the Pr in the cerium carbonate containing praseodymium is 6 O 11 / TREO is 0.1-2wt%, CeO 2 / TREO is 90-99.9wt%; the heating temperature of the upper part of the praseodymium-containing cerium carbonate is 950-1200°C, and the heating temperature of the lower part is 900-1100°C;

[0013] 2) air flow pulverizing the roasted product to obtain coarse pulverized powder;

[0014] 3) The coarse powder is sieved on a 150-350 mesh sieve to obtain rare earth polishing powder.

[0015] According to the preparation method of the present invention, preferably, the TREO containing praseodymium cerium carbonate is at least 98 wt %.

[0016] According to the preparation method of the present invention, preferably, the Pr in the cerium carbonate containing praseodymium 6 O 11 / TREO is 0.3-1.5wt%, CeO 2 / TREO is 90.5~99.7wt%.

[0017] According to the preparation method of the present invention, preferably, in step 1), the heating temperature of the upper part of the praseodymium-containing cerium carbonate is 980-1100°C, and the heating temperature of the lower part is 960-1080°C.

[0018] According to the preparation method of the present invention, preferably, in step 1), the calcination time is 2 to 10 hours.

[0019] According to the preparation method of the present invention, preferably, in step 2), the particle size D of the crushed coarse powder is 50 2~50μm, D max 20~100μm.

[0020] According to the preparation method of the present invention, preferably, in step 3), the sieve has a mesh size of 180 to 325.

[0021] On the other hand, the present invention also provides a rare earth polishing powder, which is prepared by any of the above preparation methods.

[0022] According to the rare earth polishing powder of the present invention, preferably, the rare earth polishing powder has an erosion amount of at least 0.15 mg / cm 2 ·min, the scratch rate is at most 8%.

[0023] In another aspect, the present invention also provides the use of the rare earth polishing powder in polishing crystal glass or synthetic spinel.

[0024] The method for preparing the rare earth polishing powder of the present invention directly heats and roasts the cerium carbonate containing praseodymium at the same time, which has a simple process, low preparation cost, and can significantly improve the particle uniformity of the rare earth polishing powder. The rare earth polishing powder prepared by the present invention contains praseodymium but does not contain lanthanum, and its polishing amount to the polishing piece is at least 0.15 mg / cm 2·min, the scratch rate is at most 8%, with excellent polishing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the particle size distribution diagram of the rare earth polishing powder of Example 1.

[0026] Figure 2 This is the particle size distribution diagram of the rare earth polishing powder of Comparative Example 1.

[0027] Figure 3 This is the particle size distribution diagram of the rare earth polishing powder of Comparative Example 2. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0029] The "TREO" mentioned in the present invention refers to the total amount of rare earth oxides.

[0030] The "Pr 6 O 11 / TREO” refers to Pr 6 O 11 The amount accounts for the weight ratio of TREO.

[0031] The "CeO 2 / TREO” refers to CeO 2 The amount accounts for the weight ratio of TREO.

[0032] The “polishing amount” mentioned in the present invention refers to the amount of polishing of the sample by the rare earth polishing powder per unit time and per unit area, and the unit is mg / cm 2 ·min.

[0033] The "scratch rate" mentioned in the present invention refers to the percentage of the number of polished parts with scratches on the surface after polishing by rare earth polishing powder to the total number of polished parts.

[0034] The "light transmittance" mentioned in the present invention refers to the percentage of the light flux passing through the polished part to the incident light flux.

[0035] The particle size D 50 "" refers to the particle size corresponding to when the cumulative particle size distribution percentage of a sample reaches 50%, and the unit is μm.

[0036] The particle size D max "" refers to the maximum particle size in the cumulative particle size distribution of a sample, in μm.

[0037] <Preparation method of rare earth polishing powder>

[0038] The method for preparing the rare earth polishing powder of the present invention comprises a roasting step, a jet milling step and a screening step, which are described in detail below.

[0039] Calcination steps

[0040] The cerium carbonate containing praseodymium is roasted by heating both above and below to obtain a roasted product.

[0041] According to one embodiment of the present invention, the TREO (total rare earth oxide) content in the praseodymium-containing cerium carbonate may be at least 98 wt %, preferably at least 99 wt %, and most preferably at least 99.9 wt %.

[0042] According to one embodiment of the present invention, the Pr in the cerium carbonate containing praseodymium 6 O 11 / TREO may be 0.1 to 2 wt%, preferably 0.3 to 1.5 wt%, and more preferably 0.5 to 1.0 wt%.

[0043] According to one embodiment of the present invention, CeO in the cerium carbonate containing praseodymium 2 / TREO may be 90 to 99.9 wt %, preferably 90.5 to 99.7 wt %, more preferably 91 to 99.5 wt %.

[0044] According to one embodiment of the present invention, the heating temperature of the upper part of the cerium carbonate containing praseodymium may be 950-1200°C, preferably 980-1100°C, and more preferably 1020-1080°C.

[0045] According to one embodiment of the present invention, the heating temperature of the lower portion of the cerium carbonate containing praseodymium may be 900 to 1100°C, preferably 960 to 1080°C, and more preferably 990 to 1060°C.

[0046] According to one embodiment of the present invention, the calcination time may be 2 to 10 hours, preferably 3 to 8 hours, and more preferably 4 to 6 hours.

[0047] According to one embodiment of the present invention, the cerium carbonate containing praseodymium can be in powder, strip or block form, preferably in powder form. The thickness of the cerium carbonate containing praseodymium during heating and roasting can be 2 to 10 cm, preferably 3 to 9 cm, and more preferably 5 to 8 cm. Reasonable thickness is conducive to uniform heating of the cerium carbonate containing praseodymium.

[0048] Limiting the heating temperature and roasting time of the upper and lower parts of the cerium carbonate containing praseodymium to the above range is conducive to improving the particle uniformity of the rare earth polishing powder and enhancing the polishing performance of the rare earth polishing powder. At the same time, heating the upper and lower parts of the cerium carbonate containing praseodymium at the same time can also save costs, meet the roasting requirements and product index requirements at one time, and ensure the uniformity of the particles of the polishing powder.

[0049] Airflow milling steps

[0050] The calcined product is subjected to air flow pulverization to obtain coarse pulverized powder.

[0051] According to one embodiment of the present invention, the particle size D of the crushed coarse powder is 50 It can be 2 to 50 μm, preferably 2 to 30 μm, and more preferably 2.5 to 10 μm; D max The thickness may be 20 to 100 μm, preferably 20 to 80 μm, and more preferably 25 to 50 μm.

[0052] Compared with the traditional preparation method, the present invention is optimized and improved, and uses air flow crushing instead of wet grinding, which can save a lot of manufacturing costs and improve production efficiency.

[0053] Reasonable particle size of coarse powder is beneficial to control the particle size range of powder and improve the pass rate of subsequent screening process.

[0054] In the present invention, the air flow pulverization can be achieved by using any type of air flow pulverization equipment known in the art, and is not particularly limited here, for example but not limited to an air flow pulverizer.

[0055] Screening steps

[0056] The coarse powder is sieved on a 150-350 mesh sieve to obtain rare earth polishing powder.

[0057] According to one embodiment of the present invention, the sieve may be 150-350 meshes, preferably 180-325 meshes, and more preferably 200-280 meshes.

[0058] Reasonable screening conditions are conducive to screening rare earth polishing powder with suitable particle size, and are more conducive to increasing the polishing amount of rare earth polishing powder and ensuring the surface quality of polished parts.

[0059] In the present invention, the screening can be performed in any type of screening equipment known in the art, and is not particularly limited herein, such as but not limited to an ultrasonic vibration screen.

[0060] <Rare earth polishing powder>

[0061] The invention also provides rare earth polishing powder prepared by the method.

[0062] According to one embodiment of the present invention, the erosion amount of the rare earth polishing powder on the polishing piece can be at least 0.15 mg / cm 2 min, preferably at least 0.155 mg / cm 2 ·min, more preferably at least 0.16 mg / cm 2 ·min.

[0063] According to one embodiment of the present invention, the polishing piece may be crystal glass or synthetic spinel, preferably crystal glass.

[0064] According to one embodiment of the present invention, the scratch rate of the rare earth polishing powder on the polishing piece may be at most 8%, preferably at most 5%, more preferably at most 3%, and most preferably 0%.

[0065] According to one embodiment of the present invention, the TREO of the rare earth polishing powder may be at least 97 wt %, preferably at least 98 wt %, and more preferably at least 98.5 wt %.

[0066] According to one embodiment of the present invention, the particle size D of the rare earth polishing powder is 50 The particle size D may be 1.5 to 4.00 μm, preferably 1.8 to 3.5 μm, and more preferably 2.0 to 3.0 μm. max The thickness may be 10 to 22 μm, preferably 15 to 22 μm, and more preferably 15 to 20 μm.

[0067] The rare earth polishing powder of the present invention has a high TREO content and contains praseodymium but no lanthanum, thereby increasing the cerium content and improving the wear resistance of the polishing powder, thereby having a high polishing amount and excellent polishing performance.

[0068] <Purpose>

[0069] The invention also provides use of the rare earth polishing powder in polishing crystal glass or synthetic spinel.

[0070] According to one embodiment of the present invention, after the rare earth polishing powder is used to polish the polishing piece, the surface of the polishing piece is flat, without scratches or pits. The surface transmittance of the polishing piece can be at least 95%, preferably at least 96%, and more preferably at least 98%.

[0071] <Test method>

[0072] Determination of rare earth oxides: in accordance with GB / T 18882.1-2023.

[0073] Particle size and particle size distribution were determined using the S3500 laser particle size analyzer produced by the American company Microtrac.

[0074] Determination of surface flatness, scratches and pits of polished parts: visual inspection under LED white light.

[0075] Determination of light transmittance of polished parts surface: The WTM-1100 light transmittance tester produced by Guangzhou Lantai was used.

[0076] Determination of polishing amount and scratch rate: carried out in accordance with GB / T 20167-2012; wherein, the SF-5 glass sheet is replaced by a crystal glass sheet with a specification of 100×100×3mm.

[0077] <Ingredients>

[0078] The raw materials in the following examples are all commercially available products unless otherwise specified.

[0079] Among them, cerium carbonate containing praseodymium and cerium-praseodymium carbonate containing lanthanum were purchased from Northern Rare Earth Smelting Company.

[0080] The roller kiln was purchased from Zibo Guiyuan Kiln Engineering Co., Ltd.

[0081] The muffle furnace model is Sigma SGMM30 / 12SA, purchased from Sigma (Shanghai) High Temperature Electric Furnace Co., Ltd.

[0082] Example 1

[0083] This embodiment prepares rare earth polishing powder, and the specific contents are as follows:

[0084] (1) Take cerium carbonate powder containing praseodymium (Pr 6 O 11 / TREO=0.6wt%CeO 2 / TREO=99.3wt%)5kg was added into the calcination pot and flattened to a thickness of 6cm. Then the calcination pot was placed in a roller kiln, the upper part of the cerium carbonate containing praseodymium was heated to 1050℃, the lower part was heated to 1030℃, and the calcination time was 5h to obtain a calcined product.

[0085] (2) The calcined product is subjected to air flow pulverization to obtain a coarse powder; the particle size of the coarse powder is D 50 =3μm; D max =30μm.

[0086] (3) The coarse powder is sieved on a 200-mesh sieve using an ultrasonic vibration sieve to obtain rare earth polishing powder.

[0087] Comparative Example 1

[0088] This embodiment prepares rare earth polishing powder, and the specific contents are as follows:

[0089] (1) Take lanthanum cerium praseodymium carbonate powder (Pr 6 O 11 / TREO=4.2wt%La 2 O 3 / TREO=33.23wt%CeO 2 / TREO=62.55wt%)5kg was added into the calcination pot and flattened to a thickness of 6cm. Then the calcination pot was placed in a roller kiln, the upper heating temperature of lanthanum cerium praseodymium carbonate was 1050℃, the lower heating temperature was 1030℃, the calcination time was 5h, and the calcination product was obtained.

[0090] (2) The calcined product is subjected to air flow pulverization to obtain a coarse powder; the particle size of the coarse powder is D 50 =3μm; D max =30μm.

[0091] (3) The coarse powder is sieved on a 200-mesh sieve using an ultrasonic vibration sieve to obtain rare earth polishing powder.

[0092] Comparative Example 2

[0093] This embodiment prepares rare earth polishing powder, and the specific contents are as follows:

[0094] (1) Take cerium carbonate containing praseodymium (Pr 6 O 11 / TREO=0.55wt%CeO 2 / TREO=99.4wt%)5kg was added into a calcination mortar and flattened to a thickness of 6cm. The calcination mortar was then placed in a muffle furnace and heated from the top and both sides with praseodymium-containing cerium carbonate at 1050℃ and calcination time of 5h to obtain a calcined product.

[0095] (2) The calcined product is subjected to air flow pulverization to obtain a coarse powder; the particle size of the coarse powder is D 50 =3μm; D max =30μm.

[0096] (3) The crushed product is sieved on a 200-mesh sieve using an ultrasonic vibration sieve to obtain rare earth polishing powder.

[0097] Experimental Example 1

[0098] After testing, the rare earth polishing powder prepared in Example 1 has a TREO of 98.68 wt %, and the rare earth polishing powder prepared in Comparative Example 1 has a TREO of 96.28 wt %.

[0099] The particle size distribution of the rare earth polishing powder obtained in Example 1 is as follows: Figure 1 The particle size distribution of the rare earth polishing powder prepared in Comparative Example 1 is shown in Figure 2 The particle size distribution of the rare earth polishing powder prepared in Comparative Example 2 is shown in Figure 3 shown.

[0100] like Figures 1 to 3 It can be seen that the particle size D of the rare earth polishing powder prepared in Example 1 is 50=2.24μm, particle size D max =15.56 μm. The particle size D of the rare earth polishing powder obtained in Comparative Example 1 50 =2.16μm, D max =15.56 μm. The particle size D of the rare earth polishing powder obtained in Comparative Example 2 50 =3.24μm, D max =15.56 μm. The particle size D50 of Example 1 is smaller, and there are more small particles with a cumulative particle size distribution of less than 50%, which is more conducive to improving the consistency and uniformity of the polishing effect.

[0101] Experimental Example 2

[0102] Twenty crystal glass sheets of the same quality and specifications of 100×100×3 mm were used as a group, and three groups were provided in total. The polishing powders prepared in Example 1, Comparative Example 1 and Comparative Example 2 were used to polish a group of crystal glass sheets, respectively, and the polishing effect of each crystal glass sheet in each group was tested. The results are shown in Table 1.

[0103] Table 1

[0104]

[0105]

[0106] Note: The light transmittance of the polished surface, the erosion amount of rare earth polishing powder and the scratch rate of the polished surface are all average values.

[0107] It can be seen from Table 1 that the polishing effect of the polishing powder prepared in Example 1 of the present invention is the best.

[0108] The present invention is not limited to the above-mentioned embodiments. Without departing from the essential content of the present invention, any deformation, improvement and substitution that can be conceived by those skilled in the art shall fall within the scope of the present invention.

Claims

1. A method for preparing rare earth polishing powder, comprising the following steps: 1) calcining cerium carbonate containing praseodymium by heating it from top to bottom simultaneously to obtain a calcined product; wherein Pr6O 11 / TREO is 0.1-2wt%, CeO2 / TREO is 90-99.9wt%; the heating temperature of the upper part of the praseodymium-containing cerium carbonate is 950-1200°C, and the heating temperature of the lower part is 900-1100°C; 2) air flow pulverizing the roasted product to obtain coarse pulverized powder; 3) The coarse powder is sieved on a 150-350 mesh sieve to obtain rare earth polishing powder.

2. The preparation method according to claim 1, characterized in that: The TREO containing cerium praseodymium carbonate is at least 98 wt%.

3. The preparation method according to claim 1, characterized in that: The Pr6O in the cerium carbonate containing praseodymium 11 / TREO is 0.3~1.5wt%, CeO2 / TREO is 90.5~99.7wt%.

4. The preparation method according to claim 1, characterized in that: In step 1), the heating temperature of the upper part of the praseodymium-containing cerium carbonate is 980-1100°C, and the heating temperature of the lower part is 960-1080°C.

5. The preparation method according to claim 1, characterized in that: In step 1), the calcination time is 2 to 10 hours.

6. The preparation method according to claim 1, characterized in that: In step 2), the particle size D of the crushed coarse powder is 50 2~50μm, D max 20~100μm.

7. The preparation method according to claim 1, characterized in that: In step 3), the sieve is 180-325 mesh.

8. A rare earth polishing powder, characterized in that: The rare earth polishing powder is prepared by the preparation method according to any one of claims 1 to 7.

9. The rare earth polishing powder according to claim 8, characterized in that: The rare earth polishing powder has an erosion rate of at least 0.15 mg / cm 2 ·min, the scratch rate is at most 8%.

10. Use of the rare earth polishing powder according to claim 8 or 9 in polishing crystal glass or synthetic spinel.

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