High-corrosion-resistance medicinal glass rotating tube and preparation method thereof

Abstract

The invention relates to the technical field of glass preparation, in particular to a high-corrosion-resistance medicinal glass rotating tube and a preparation method thereof, and aims to solve the problems that an existing mullite rotating tube is poor in corrosion resistance, and a high-zirconium rotating tube is prone to cracks. According to the scheme, the waste borosilicate glass is introduced into an aluminum oxide (main crystal phase alpha-Al2O3) matrix with relatively good high-temperature stability, so that Na < + > in molten glass is effectively locked, the added CaO and MgO can promote conversion from gamma-Al2O3 to alpha-Al2O3 at a relatively low temperature (alpha-Al2O3 has relatively good high-temperature stability), and meanwhile, the formed composite borate CaMgB2O5 can inhibit growth of ZrO2 crystal grains and stabilize a cubic phase of ZrO2, so that the high-temperature stability of ZrO2 is improved. Cracking caused by crystal transformation is avoided, thermal shock resistance can be effectively improved, the service life of the rotating pipe is prolonged, and the adverse effect of the rotating pipe on the product quality is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of glass preparation, and particularly relates to a highly corrosion-resistant medicinal glass rotary tube and a preparation method thereof. Background Art

[0002] In the production of medicinal glass draw tubes by the Danner process, the rotary tube is an essential core component in the production. The existing rotary tubes are mostly made of mullite or high zirconium (precious metal rotary tubes are costly and rarely used in China), but their service lives are relatively short, resulting in frequent replacement of the rotary tubes, which has become a bottleneck for draw tube manufacturers to improve production capacity and quality. The main reasons are as follows: 1. Mullite rotary tube: Mullite (Al2O3.SiO2) is a kind of acidic oxide with poor resistance to alkali ion erosion, which is manifested in: ① The chemical composition of medicinal glass contains alkali ions such as K+ and Na+. At high temperatures, mullite is very easy to react with alkali ions such as K+ and Na+ in the glass melt to form nepheline (Na2O.Al2O3. 2SiO2), feldspar (Na2O.Al2O3.6SiO2, K2O.Al2O3. 6SiO2) crystals, which affects the quality of glass products. With the aggravation of erosion, the surface of the rotary tube becomes uneven and loses its effectiveness; ② Due to the physical properties and preparation process of mullite refractory materials, the porosity is relatively high (20% - 30%). The surface tension of the glass melt rich in alkali ions is small, and it is easy to erode the pores, reducing the structural strength. At the same time, the gas escaping from the pores forms bubbles in the glass melt, affecting the quality of glass products.

[0003] The above erosion reasons have a serious impact on the strength and service life of mullite rotary tubes.

[0004] 2. High zirconium rotary tube: When using a high zirconium rotary tube, it is found that bubbles and crystallization will occur in the glass melt in a very short period of time. The main reasons are: ① The high zirconium rotary tube has a high ZrO2 content and high density. The temperature difference between the front and rear ends, the inner and outer walls of the rotary tube is large, up to 300℃ - 500℃, resulting in relatively large internal thermal stress in the rotary tube. When the stress is concentrated to a certain extent, microcracks will occur in the rotary tube; ZrO2 has a phase transformation between monoclinic and tetragonal crystal forms at 900℃ - 1200℃, and the volume densities of monoclinic crystals and tetragonal crystals are quite different (about 7%). During the phase transformation, it is easy to cause cracking of the product. The forming temperature of the rotary tube is between 850℃ - 1300℃, which includes the ZrO2 phase transformation temperature, which is an important reason for the generation of cracks in the rotary tube; When the microcracks expand to a certain extent, gas will be accumulated, resulting in bubbles at the contact area between the glass melt and the rotary tube, affecting the quality of glass products.

[0005] ②The high-zirconia rotating tube has a high ZrO2 content. Under the action of alkali ions in the glass melt, Zr +4 ions will be generated. Zr +4 ions are a kind of nucleating agent. If the concentration is too high and at this forming temperature, it will cause crystallization and affect the quality of glass products. Summary of the Invention

[0006] The present invention provides a highly corrosion-resistant pharmaceutical glass rotating tube and a preparation method thereof to alleviate the problems of poor erosion resistance of the existing mullite rotating tube and easy generation of cracks in the high-zirconia rotating tube.

[0007] In order to alleviate the above technical problems, the technical solution provided by the present invention is as follows: A highly corrosion-resistant pharmaceutical glass rotating tube, comprising the following components in parts by mass: Aluminum oxide: 70-80 parts; Zirconium oxide: 3-5 parts; Silicon oxide: 3-5 parts; The total of calcium oxide and magnesium oxide: 3-5 parts, wherein the molar ratio of calcium oxide to magnesium oxide is 1:1; The total of cerium oxide and yttrium oxide: 5-7 parts, wherein the molar ratio of cerium oxide to yttrium oxide is 1:1; Silicon carbide: 4-7 parts; Waste borosilicate glass: 2-15 parts, wherein, first, the waste borosilicate glass is pickled to remove surface sodium ions. When B2O3 < 10%, mixed boron mud or H3BO3 calcined product is added to make B2O3 ≥ 10%. Calculate the molar content of Na2O in the waste borosilicate glass, and add quicklime in a molar ratio of 1:1 to form calcium sodium borate at high temperature to fix sodium.

[0008] Furthermore, The particle size of aluminum oxide is 2-8 μm.

[0009] Furthermore, The particle size of zirconium oxide is 3-10 μm.

[0010] Furthermore, The particle size of silicon oxide is 2-8 μm.

[0011] Furthermore, The particle sizes of calcium oxide and magnesium oxide are both 2-8 μm.

[0012] Furthermore, The particle sizes of cerium oxide and yttrium oxide are both 5-10 μm.

[0013] Furthermore, The particle size of silicon carbide is 10-50 μm.

[0014] Furthermore, The waste borosilicate glass comprises, by mass parts: 70 - 85 parts of SiO2; 8 - 12 parts of B2O3; 3 - 10 parts of Na2O and / or K2O; 0 - 5 parts of Al2O3; 0 - 3 parts of CaO.

[0015] A preparation method of a highly corrosion-resistant medicinal glass rotary tube comprises the following steps: Pickle the waste borosilicate glass to remove surface sodium ions, take samples to measure the percentage content of each component. If the B2O3 in the waste borosilicate glass is < 10%, mix borax mud or calcined H3BO3 to make B2O3 ≥ 10%, calculate the molar content of Na2O in the waste borosilicate glass, and add quicklime in a ratio of 1:1 in molar ratio to form sodium calcium borate at high temperature to fix sodium.

[0016] Grind the waste borosilicate glass that has been pickled and sodium-fixed into powder; Add the waste borosilicate glass powder, alumina, zirconia, silica, calcium oxide, magnesium oxide, cerium oxide, yttrium oxide and silicon carbide into a high-speed mixer, first perform dry mixing for 10 - 15 minutes, then add a phosphate binder and water, and perform wet mixing for 15 - 20 minutes; Pass the mixed slurry through a spinning press and use centrifugal force to spin it into a circular tube blank; Put the formed blank into a drying chamber for low-temperature drying, and the drying time is 4 - 6 hours; Put the dried blank into a high-temperature kiln for firing, the firing temperature is between 1600 - 1700 °C, and the firing time is 6 - 8 hours; After firing is completed, cool it to room temperature, and the cooling rate is 100 - 150 °C / hour.

[0017] The beneficial effects of the highly corrosion-resistant medicinal glass rotary tube in the present invention are analyzed as follows: 1. The metaborate (KBO2 / NaBO2) formed by the remaining B2O3 in the waste borosilicate glass in the rotary tube after sodium-fixing treatment can be used to lock Na in the glass melt, + reduce the migration of free alkali metal ions, thereby reducing the erosion of alkali metal ions on the main crystal phase.

[0018] 2. CaO and MgO can accelerate the transformation of γ-Al2O3 to α-Al2O3 at a lower temperature, so that the alumina retains a higher α-Al2O3 crystal phase, greatly improving the high-temperature corrosion resistance of the rotary tube.

[0019] 3. CaO and MgO enter the B2O3 network to form a stable phase CaMgB2O5 with a relatively high melting point (a composite borate with a low coefficient of thermal expansion). CaMgB2O5 can effectively inhibit the grain growth of ZrO2, stabilize the cubic phase of ZrO2 (instead of the easily cracked monoclinic phase), and maintain a fine and uniform grain structure (nano / sub-micron scale). At the same time, the coefficient of thermal expansion of CaMgB2O5 is lower than that of ZrO2, which can buffer the thermal stress of ZrO2 and reduce the risk of interface cracking. In addition, CaMgB2O5 has a stabilizing effect. CaMgB2O5 wraps the ZrO2 particles to form a diffusion barrier, hindering the 2- migration of O 2+ and inhibiting the transformation from the monoclinic phase to the tetragonal phase. Mg 2+ and Ca 4+ partially replace Zr ' to form a defect solid solution, reducing the phase transformation temperature, so that ZrO2 remains in the metastable tetragonal phase (t

[0020] -ZrO2) at the working temperature (850–1300 °C), avoiding volume mutation. In addition, the B2O3 glass phase wraps the ZrO2 particles, reducing the erosion of ZrO2 in the rotary tube by alkali metal ions in the glass melt.

[0021] 4. Rare earth elements cerium oxide and yttrium oxide have relatively high melting points and good chemical stability. They can maintain the structural integrity of the material at high temperatures, thereby enhancing the high-temperature strength of the rotary tube. They can also inhibit the grain growth of Al2O3 and ZrO2 and maintain the stability of the microstructure of the rotary tube. Cerium oxide and yttrium oxide can fill the tiny voids in the material, reduce the occurrence of creep, maintain the stability of the structural dimensions of the rotary tube, and improve the dimensional accuracy and yield of the product. 5. Silicon carbide can inhibit the grain growth of Al2O3 and ZrO2 and maintain the stability of the microstructure of the rotary tube. At the same time, it has good bonding with the main crystal phase alumina, enhancing the overall strength and toughness of the rotary tube. More importantly, silicon carbide still has relatively high hardness and strength at high temperatures, and its wear resistance is very excellent, greatly enhancing the ability of the rotary tube to resist glass melt erosion and significantly extending the service life of the rotary tube. Specific Embodiments

[0022] The test methods are as follows: Erosion resistance (erosion rate, mm / h): Place the rotary tube specimen in the glass melt at 1300 °C and conduct a dynamic erosion experiment under simulated actual production conditions. Take out the specimen at regular intervals, measure the surface erosion depth, and calculate the average erosion rate per unit time.

[0023] Thermal shock performance (number of cycles): Keep the rotary tube specimen at 1300 °C for a certain period of time, and then quickly cool it to room temperature (such as water quenching or air cooling). Record the number of cycles before cracks appear on the specimen.

[0024] Glass liquid quality: Statistically calculate the percentage of the number of bubbles in the glass liquid accounting for the total observation area.

[0025] Example 1: Pickle the waste borosilicate glass with 5% HNO3 to remove the surface Na + . Add boron mud until the B2O3 content reaches 10%; add quicklime with the molar ratio of Na2O to quicklime in the waste borosilicate glass being 1:1, and generate sodium calcium borate at high temperature to fix sodium; grind.

[0026] Weigh by mass: 75 parts of alumina; 4 parts of zirconia; 4 parts of silica; 4 parts of calcium oxide and magnesium oxide (molar ratio 1:1); 6 parts of cerium oxide and yttrium oxide (molar ratio 1:1); 5 parts of silicon carbide; 4 parts of the treated waste borosilicate glass powder.

[0027] Add the weighed raw materials into a high-speed mixer, first perform dry mixing for 10 - 15 minutes, then add an appropriate amount of binder (such as phosphate binder) and water, and perform wet mixing for 15 - 20 minutes. Pass the mixed slurry through a spinning press and use centrifugal force to spin it into a circular tubular green body. Put the formed green body into a drying chamber and conduct low-temperature (≤100°C) drying, with the drying time controlled within 4 - 6 hours to ensure that the green body is completely dried. Put the dried green body into a high-temperature kiln for firing, with the firing temperature controlled between 1600 - 1700°C and the firing time about 6 - 8 hours. After firing is completed, slowly cool the material to room temperature. Control the cooling rate at 100 - 150°C / h during the cooling process to avoid cracks caused by thermal stress.

[0028] Performance analysis: Erosion resistance: The erosion rate on the surface of the rotating tube ≤ 0.05 mm / h (scoured by glass liquid at 1300°C) Thermal shock performance: Cycle 30 times (1300°C Room temperature).

[0029] Glass liquid quality: Bubble rate 0.02%.

[0030] Principle analysis: The waste borosilicate glass reacts with CaO at high temperature to form Na2CaB2O5, locking sodium + . The remaining B2O3 forms CaMgB2O5 (complex borate) with CaO / MgO.

[0031] Comparative example 1: Pickle the waste borosilicate glass with 5% HNO3 to remove the surface Na +。After detection, the B2O3 content in the waste borosilicate glass is 5%, and boron is not supplemented. Quicklime is added in a molar ratio of Na2O to quicklime in the waste borosilicate glass of 1:1, and sodium calcium borate is formed at high temperature to fix sodium, followed by grinding.

[0032] Weigh by mass parts: 75 parts of alumina; 4 parts of zirconia; 4 parts of silica; 4 parts of calcium oxide and magnesium oxide (molar ratio 1:1); 6 parts of cerium oxide and yttrium oxide (molar ratio 1:1); 5 parts of silicon carbide; 2 parts of the treated waste borosilicate glass powder.

[0033] Add the weighed raw materials into a high-speed mixer, first perform dry mixing for 10 - 15 minutes, then add an appropriate amount of binder (such as phosphate binder) and water, and perform wet mixing for 15 - 20 minutes. Pass the mixed slurry through a spinning press and use centrifugal force to spin it into a circular tubular green body. Place the formed green body in a drying chamber and conduct low-temperature (≤100°C) drying, with the drying time controlled within 4 - 6 hours to ensure that the green body is completely dry. Place the dried green body in a high-temperature kiln for firing, with the firing temperature controlled between 1600 - 1700°C and the firing time about 6 - 8 hours. After firing is completed, slowly cool the material to room temperature. During the cooling process, control the cooling rate at 100 - 150°C / hour to avoid cracks caused by thermal stress.

[0034] Erosion resistance: Erosion rate 0.12 mm / h, Thermal shock performance: Cycle 24 times (1300°C room temperature).

[0035] Quality of glass liquid: Bubble rate 0.3%.

[0036] Principle analysis: Insufficient B2O3, and composite borate is not fully formed.

[0037] Comparative example 2 Weigh by mass parts: 75 parts of alumina; 4 parts of zirconia; 4 parts of silica; 4 parts of calcium oxide and magnesium oxide (molar ratio 1:1); 6 parts of cerium oxide and yttrium oxide (molar ratio 1:1); 5 parts of silicon carbide; Add the weighed raw materials into a high-speed mixer, first conduct dry mixing for 10 - 15 minutes, then add an appropriate amount of binder (such as phosphate binder) and water, and conduct wet mixing for 15 - 20 minutes. Pass the mixed slurry through a spinning press and use centrifugal force to spin it into a circular tubular blank. Place the formed blank into a drying chamber and conduct low-temperature (≤100°C) drying, with the drying time controlled within 4 - 6 hours to ensure the blank is completely dry. Place the dried blank into a high-temperature kiln for firing, with the firing temperature controlled between 1600 - 1700°C and the firing time about 6 - 8 hours. After firing is completed, slowly cool the material to room temperature. Control the cooling rate at 100 - 150°C / h during the cooling process to avoid cracks caused by thermal stress.

[0038] Erosion resistance: Erosion rate 0.25 mm / h Thermal shock performance: Cycle 21 times (1300°C Room temperature).

[0039] Quality of glass melt: Bubble rate 0.8%.

[0040] Principle analysis: No B2O3-CaO-MgO synergistic protection.

[0041] Comparative example 3: Pickle the waste borosilicate glass with 5% HNO3 to remove surface Na + . Add boron mud until the B2O3 content reaches 10%; add quicklime according to the molar ratio of Na2O in the waste borosilicate glass to quicklime of 1:1, and generate sodium calcium borate at high temperature to fix sodium; grind.

[0042] Weigh by mass: 75 parts of alumina; 4 parts of zirconia; 4 parts of silica; 6 parts of cerium oxide and yttrium oxide (molar ratio 1:1); 5 parts of silicon carbide; 4 parts of the treated waste borosilicate glass powder.

[0043] Add the weighed raw materials into a high-speed mixer, first conduct dry mixing for 10 - 15 minutes, then add an appropriate amount of binder (such as phosphate binder) and water, and conduct wet mixing for 15 - 20 minutes. Pass the mixed slurry through a spinning press and use centrifugal force to spin it into a circular tubular blank. Place the formed blank into a drying chamber and conduct low-temperature (≤100°C) drying, with the drying time controlled within 4 - 6 hours to ensure the blank is completely dry. Place the dried blank into a high-temperature kiln for firing, with the firing temperature controlled between 1600 - 1700°C and the firing time about 6 - 8 hours. After firing is completed, slowly cool the material to room temperature. Control the cooling rate at 100 - 150°C / h during the cooling process to avoid cracks caused by thermal stress.

[0044] Erosion resistance: Erosion rate 0.18 mm / h (no CaMgB2O5 is formed, Na +Volatilization intensifies erosion).

[0045] Thermal shock performance: 19 cycles (1300 °C room temperature).

[0046] Quality of glass liquid: bubble rate 0.6%.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high corrosion-resistant pharmaceutical glass rotating tube, characterized in that: Comprises the following components by mass parts: Aluminum oxide: 70 - 80 parts; Zirconium oxide: 3 - 5 parts; Silicon oxide: 3 - 5 parts; Total of calcium oxide and magnesium oxide: 3 - 5 parts, wherein the molar ratio of calcium oxide to magnesium oxide is 1:1; Total of cerium oxide and yttrium oxide: 5 - 7 parts, wherein the molar ratio of cerium oxide to yttrium oxide is 1:1; Silicon carbide: 4 - 7 parts; Waste borosilicate glass: 2 - 15 parts, wherein the waste borosilicate glass is first pickled with acid to remove surface sodium ions. When B2O3 < 10%, mixed boron mud or H3BO3 calcined product is added to make B2O3 ≥ 10%. Calculate the molar content of Na2O in the waste borosilicate glass, and add quicklime in a molar ratio of 1:1 to form sodium calcium borate at high temperature to fix sodium. The waste borosilicate glass by mass parts includes: SiO2 70 - 85 parts; B2O3 8 - 12 parts; Na2O and / or K2O 3 - 10 parts; Al2O3 0 - 5 parts; CaO 0 - 3 parts.

2. The high corrosion-resistant medicinal glass rotary tube according to claim 1, characterized in that: The waste borosilicate glass is pickled with 5% - 10% concentration of HNO3.

3. The high corrosion-resistant medicinal glass rotary tube according to claim 1, characterized in that: The particle size of aluminum oxide is 2 - 8 μm.

4. The high corrosion-resistant medicinal glass rotary tube according to claim 1, characterized in that: The particle size of zirconium oxide is 3 - 10 μm.

5. The high corrosion-resistant medicinal glass rotary tube according to claim 1, characterized in that: The particle size of silicon oxide is 2 - 8 μm.

6. The high corrosion-resistant medicinal glass rotary tube according to claim 1, characterized in that: The particle sizes of calcium oxide and magnesium oxide are both 2 - 8 μm.

7. The high corrosion-resistant medicinal glass rotary tube according to claim 1, characterized in that: The particle sizes of cerium oxide and yttrium oxide are both 5 - 10 μm.

8. The high corrosion-resistant medicinal glass rotary tube according to claim 1, characterized in that: The particle size of silicon carbide is 10 - 50 μm.

9. A method for preparing a highly corrosion-resistant pharmaceutical glass rotary tube according to any one of claims 1-8, characterized in that: Comprises the following steps: Pickle the waste borosilicate glass to remove surface sodium ions. When B2O3 < 10%, mix boron mud or H3BO3 calcined product to make B2O3 ≥ 10%. Calculate the molar content of Na2O in the waste borosilicate glass, and add quicklime in a molar ratio of 1:1 to form sodium calcium borate at high temperature to fix sodium; Grind the pickled and sodium-fixed waste borosilicate glass into powder; Add the waste borosilicate glass powder, aluminum oxide, zirconium oxide, silicon oxide, calcium oxide, magnesium oxide, cerium oxide, yttrium oxide and silicon carbide into a high-speed mixer, first dry mix for 10 - 15 minutes, then add a phosphate binder and water, and wet mix for 15 - 20 minutes; Pass the mixed slurry through a spinning press and use centrifugal force to spin it into a circular tube blank; Put the formed blank into a drying chamber for low-temperature drying, and the drying time is 4 - 6 hours; Put the dried blank into a high-temperature kiln for firing, the firing temperature is between 1600 - 1700 °C, and the firing time is 6 - 8 hours; After firing is completed, cool to room temperature, and the cooling rate is 100 - 150 °C / hour.