A high-corrosion-resistant medicinal glass rotary tube and its preparation method

Abstract

The present invention relates to the field of glass preparation technology, and in particular to a highly corrosion-resistant pharmaceutical glass rotating tube and its preparation method, in order to alleviate the problems of poor corrosion resistance of existing mullite rotating tubes and the easy cracking of high-zirconium rotating tubes. This solution effectively locks the Na in the glass liquid by introducing waste borosilicate glass into an alumina (main crystal phase α-Al2O3) matrix with good high-temperature stability. + The added CaO and MgO can promote the conversion of γ-Al2O3 to α-Al2O3 at a lower temperature (α-Al2O3 has better high-temperature stability). At the same time, the formed composite borate CaMgB2O5 can inhibit the growth of ZrO2 grains, stabilize the cubic phase of ZrO2, avoid cracking caused by crystal transformation, and effectively improve the thermal shock resistance, thereby extending the service life of the rotary tube and reducing the adverse effects of the rotary tube on product quality.

Description

Technical Field

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

[0002] In the production of pharmaceutical glass drawn tubes using the Danner process, the rotary tube is an essential core component. Existing rotary tubes are mostly made of mullite or high zirconium (precious metal rotary tubes are expensive and rarely used in China), but their service life is relatively short. Frequent replacement of rotary tubes has become a bottleneck for drawn tube manufacturers to improve production capacity and quality. The main reasons are as follows:

[0003] 1. Mullite rotary tube: Mullite (Al2O3.SiO2) is a slightly acidic oxide with poor resistance to alkali ion corrosion, which is manifested in:

[0004] ① The chemical composition of pharmaceutical glass contains alkali ions such as K+ and Na+. At high temperatures, mullite easily corrodes with alkali ions such as K+ and Na+ in the glass liquid to form nepheline (Na2O.Al2O3.2SiO2) and feldspar (Na2O.Al2O3.6SiO2, K2O.Al2O3.6SiO2) crystals, affecting the quality of glass products. As the corrosion intensifies, the surface of the rotating tube becomes uneven and loses its performance.

[0005] ② The physical properties of mullite refractory materials and their preparation process have a high porosity (20% to 30%). The surface tension of the glass liquid rich in alkali ions is small, which can easily corrode the pores and reduce 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.

[0006] The above erosion causes have a serious impact on the strength and service life of the mullite rotary tube.

[0007] 2. High zirconium rotating tube:

[0008] When using a high-zirconium rotary tube, it is found that bubbles and crystallization will occur in the glass liquid after a short period of use. The main reasons are:

[0009] ① The high zirconium rotating tube has a high ZrO2 content and high density. The temperature difference between the front and rear ends and the inner and outer walls of the rotating tube is large, which can reach 300℃~500℃, resulting in large thermal stress inside the rotating tube. When the stress concentrates to a certain extent, the rotating tube will produce microcracks; ZrO2 undergoes a transformation from monoclinic to tetragonal crystals at 900℃~1200℃. The volume density difference between monoclinic and tetragonal crystals is large (about 7%), which can easily cause product cracking during crystal transformation. The molding temperature of the rotating tube is between 850℃~1300℃, which includes the ZrO2 crystal transformation temperature. This is an important reason for the cracks in the rotating tube; when the microcracks expand to a certain extent, gas will gather, causing bubbles to form at the contact between the glass liquid and the rotating tube, which affects the quality of the glass products.

[0010] ② The high zirconium rotating tube has a high ZrO2 content. Under the action of alkali ions in the glass liquid, it will produce a strong Zr field. +4 ions, Zr +4 Ions are a nucleating agent. If the concentration is too high and at this molding temperature, it will cause crystallization and affect the quality of the glass product. Summary of the Invention

[0011] The invention provides a high-corrosion-resistant medicinal glass rotating tube and a preparation method thereof, so as to alleviate the problems that the existing mullite rotating tube has poor corrosion resistance and the high-zirconium rotating tube is prone to cracking.

[0012] In order to alleviate the above technical problems, the technical solution provided by the present invention is:

[0013] A highly corrosion-resistant pharmaceutical glass rotary tube comprises the following components in parts by mass:

[0014] Alumina: 70-80 parts;

[0015] Zirconium oxide: 3-5 parts;

[0016] Silicon oxide: 3-5 parts;

[0017] Calcium oxide and magnesium oxide in total: 3-5 parts, wherein the molar ratio of calcium oxide to magnesium oxide is 1:1;

[0018] Total of cerium oxide and yttrium oxide: 5 to 7 parts, wherein the molar ratio of cerium oxide to yttrium oxide is 1:1;

[0019] Silicon carbide: 4-7 parts;

[0020] Waste borosilicate glass: 2-15 parts, wherein the waste borosilicate glass is first pickled to remove surface sodium ions, and when B2O3 <10%, it is mixed with boron mud or H3BO3 calcined product to make B2O3 ≥10%, and the molar content of Na2O in the waste borosilicate glass is calculated. Quicklime is added in a molar ratio of 1:1 to generate sodium calcium borate at high temperature to fix sodium.

[0021] Furthermore,

[0022] The particle size of alumina is 2-8 μm.

[0023] Furthermore,

[0024] The particle size of zirconium oxide is 3-10 μm.

[0025] Furthermore,

[0026] The silica particle size is 2-8 μm.

[0027] Furthermore,

[0028] The particle size of calcium oxide and magnesium oxide is 2-8 μm.

[0029] Furthermore,

[0030] The particle sizes of cerium oxide and yttrium oxide are both 5-10 μm.

[0031] Furthermore,

[0032] The particle size of silicon carbide is 10-50 μm.

[0033] Furthermore,

[0034] The waste borosilicate glass comprises, by mass, 70-85 parts of SiO2; 8-12 parts of B2O3; 3-10 parts of Na2O and / or K2O3; 0-5 parts of Al2O3; and 0-3 parts of CaO.

[0035] A method for preparing a highly corrosion-resistant pharmaceutical glass rotary tube comprises the following steps:

[0036] Waste borosilicate glass is acid-washed to remove surface sodium ions, and samples are taken to determine the percentage of each component. If the B2O3 in the waste borosilicate glass is less than 10%, boron mud or H3BO3 calcined product is mixed to make B2O3 ≥ 10%. The molar content of Na2O in the waste borosilicate glass is calculated, and quicklime is added in a molar ratio of 1:1 to generate sodium calcium borate at high temperature to fix sodium.

[0037] Grinding the waste borosilicate glass that has been acid-washed and sodium-solidified into powder;

[0038] Add 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 and dry-mix for 10-15 minutes. Then add phosphate binder and water and wet-mix for 15-20 minutes. Pass the mixed slurry through a spinning machine and spin it into a cylindrical body using centrifugal force.

[0039] Place the formed green body in a drying chamber for low-temperature drying for 4-6 hours;

[0040] The dried green body is placed in a high temperature kiln for firing at a temperature between 1600-1700°C for 6-8 hours;

[0041] After sintering, the mixture was cooled to room temperature at a cooling rate of 100-150°C / hour.

[0042] The beneficial effects of the highly corrosion-resistant pharmaceutical glass rotary tube of the present invention are analyzed as follows:

[0043] 1. The waste borosilicate glass in the rotating tube is treated with sodium solidification, and the residual B2O3 generates metaborate (KBO2 / NaBO2) which can be used to lock the Na in the glass liquid. + , reducing the migration of free alkali metal ions, thereby reducing the erosion of alkali metal ions on the main crystal phase.

[0044] 2. CaO and MgO can accelerate the conversion of γ-Al2O3 to α-Al2O3 at a lower temperature, so that alumina retains a higher α-Al2O3 crystal phase, greatly improving the high-temperature corrosion resistance of the rotating tube.

[0045] 3. CaO and MgO enter the B2O3 network to generate a stable phase CaMgB2O5 (complex borate, low thermal expansion coefficient) with a higher melting point. CaMgB2O5 can effectively inhibit the growth of ZrO2 grains, stabilize the cubic phase of ZrO2 (rather than the monoclinic phase that is easy to crack), and maintain a fine and uniform grain structure (nanometer / submicron level). At the same time, the thermal expansion coefficient 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 O 2- migration, inhibiting the transformation of monoclinic phase to tetragonal phase, Mg 2+ and Ca 2+ Partially replace Zr 4+ (forming defective solid solution), lowering the phase transition temperature, and keeping ZrO2 in the metastable tetragonal phase (t ' -ZrO2), avoiding sudden volume changes. In addition, the B2O3 glass phase encapsulates the ZrO2 particles, reducing the erosion of the ZrO2 in the rotating tube by the alkali metal ions in the glass liquid.

[0046] 4. The rare earth elements cerium oxide and yttrium oxide have high melting points and excellent chemical stability. They can maintain the structural integrity of the material at high temperatures, thereby enhancing the high-temperature strength of the rotating tube. They can also inhibit the growth of Al2O3 and ZrO2 grains, maintaining the microstructure of the rotating tube. Cerium oxide and yttrium oxide can fill tiny gaps in the material, reduce creep, maintain the structural stability of the rotating tube, and improve the dimensional accuracy and yield rate of the product.

[0047] 5. Silicon carbide can inhibit the growth of Al2O3 and ZrO2 grains, maintain the stability of the microstructure of the rotating tube, and at the same time has good bonding with the main crystal phase alumina, enhancing the overall strength and toughness of the rotating tube. More importantly, silicon carbide still has high hardness and strength at high temperatures, and its wear resistance is very excellent, which greatly enhances the ability of the rotating tube to resist glass liquid erosion and greatly extends the service life of the rotating tube. DETAILED DESCRIPTION

[0048] The test method is as follows:

[0049] Erosion resistance (erosion rate, mm / h): Rotating tube specimens were placed in molten glass at 1300°C to simulate actual production conditions and undergo a dynamic erosion test. Samples were removed at regular intervals, the surface erosion depth was measured, and the average erosion rate per unit time was calculated.

[0050] Thermal shock performance (number of cycles): The rotating tube specimen is kept at a high temperature of 1300℃ for a certain period of time, and then quickly cooled to room temperature (such as water quenching or air cooling), and the number of cycles before cracks appear on the specimen is recorded.

[0051] Glass liquid quality: Count the number of bubbles in the glass liquid as a percentage of the total observation area.

[0052] Example 1:

[0053] The waste borosilicate glass was washed with 5% HNO3 to remove the surface Na + Add boron mud until the B2O3 content reaches 10%; add quicklime at a molar ratio of 1:1 between Na2O and quicklime in the waste borosilicate glass, generate sodium calcium borate at high temperature to solidify the sodium; grind.

[0054] Weigh in parts by mass: 75 parts of aluminum oxide; 4 parts of zirconium oxide; 4 parts of silicon oxide; 4 parts of calcium oxide and magnesium oxide (molar ratio of 1:1); 6 parts of cerium oxide and yttrium oxide (molar ratio of 1:1); 5 parts of silicon carbide; and 4 parts of treated waste borosilicate glass powder.

[0055] Add the weighed raw materials to a high-speed mixer and dry-mix for 10-15 minutes. Then, add an appropriate amount of binder (such as a phosphate binder) and water and wet-mix for 15-20 minutes. The mixed slurry is passed through a spinning machine, where it is centrifugally spun into a tubular body. The formed body is placed in a drying chamber and dried at a low temperature (≤100°C) for 4-6 hours to ensure complete dryness. The dried body is then fired in a high-temperature kiln at a temperature between 1600-1700°C for approximately 6-8 hours. After firing, the material is slowly cooled to room temperature. During the cooling process, maintain a cooling rate of 100-150°C / hour to avoid cracks caused by thermal stress.

[0056] Performance Analysis:

[0057] Erosion resistance: Rotating tube surface erosion rate ≤ 0.05 mm / h (1300℃ glass liquid erosion)

[0058] Thermal shock resistance: 30 cycles (1300℃ room temperature).

[0059] Glass liquid quality: bubble rate 0.02%.

[0060] Principle analysis: Waste borosilicate glass reacts with CaO at high temperature to generate Na2CaB2O5, locking Na + The remaining B2O3 reacts with CaO / MgO to form CaMgB2O5 (complex borate).

[0061] Comparative Example 1:

[0062] The waste borosilicate glass was washed with 5% HNO3 to remove the surface Na + The B2O3 content in the waste borosilicate glass was determined to be 5%, indicating no boron supplementation. Quicklime was added to the waste borosilicate glass at a molar ratio of 1:1, generating sodium calcium borate at high temperature to solidify the sodium, which was then ground.

[0063] Weigh in parts by mass: 75 parts of aluminum oxide; 4 parts of zirconium oxide; 4 parts of silicon oxide; 4 parts of calcium oxide and magnesium oxide (molar ratio of 1:1); 6 parts of cerium oxide and yttrium oxide (molar ratio of 1:1); 5 parts of silicon carbide; and 2 parts of treated waste borosilicate glass powder.

[0064] Add the weighed raw materials to a high-speed mixer and dry-mix for 10-15 minutes. Then, add an appropriate amount of binder (such as a phosphate binder) and water and wet-mix for 15-20 minutes. The mixed slurry is passed through a spinning machine, where it is centrifugally spun into a tubular body. The formed body is placed in a drying chamber and dried at a low temperature (≤100°C) for 4-6 hours to ensure complete dryness. The dried body is then fired in a high-temperature kiln at a temperature between 1600-1700°C for approximately 6-8 hours. After firing, the material is slowly cooled to room temperature. During the cooling process, maintain a cooling rate of 100-150°C / hour to avoid cracks caused by thermal stress.

[0065] Erosion resistance: erosion rate 0.12 mm / h,

[0066] Thermal shock resistance: 24 cycles (1300℃ room temperature).

[0067] Glass liquid quality: bubble rate 0.3%.

[0068] Principle analysis: Insufficient B2O3 and insufficient formation of complex borate.

[0069] Comparative Example 2

[0070] Weigh by mass: 75 parts of aluminum oxide; 4 parts of zirconium oxide; 4 parts of silicon oxide; 4 parts of calcium oxide and magnesium oxide (molar ratio of 1:1); 6 parts of cerium oxide and yttrium oxide (molar ratio of 1:1); 5 parts of silicon carbide;

[0071] Add the weighed raw materials to a high-speed mixer and dry-mix for 10-15 minutes. Then, add an appropriate amount of binder (such as a phosphate binder) and water and wet-mix for 15-20 minutes. The mixed slurry is passed through a spinning machine, where it is centrifugally spun into a tubular body. The formed body is placed in a drying chamber and dried at a low temperature (≤100°C) for 4-6 hours to ensure complete dryness. The dried body is then fired in a high-temperature kiln at a temperature between 1600-1700°C for approximately 6-8 hours. After firing, the material is slowly cooled to room temperature. During the cooling process, maintain a cooling rate of 100-150°C / hour to avoid cracks caused by thermal stress.

[0072] Erosion resistance: erosion rate 0.25 mm / h

[0073] Thermal shock resistance: 21 cycles (1300℃ room temperature).

[0074] Glass liquid quality: bubble rate 0.8%.

[0075] Principle analysis: No B2O3-CaO-MgO synergistic protection.

[0076] Comparative Example 3:

[0077] The waste borosilicate glass was washed with 5% HNO3 to remove the surface Na + Add boron mud until the B2O3 content reaches 10%; add quicklime at a molar ratio of 1:1 between Na2O and quicklime in the waste borosilicate glass, generate sodium calcium borate at high temperature to solidify the sodium; grind.

[0078] Weigh in parts by mass: 75 parts of aluminum oxide; 4 parts of zirconium oxide; 4 parts of silicon oxide; 6 parts of cerium oxide and yttrium oxide (molar ratio of 1:1); 5 parts of silicon carbide; and 4 parts of treated waste borosilicate glass powder.

[0079] Add the weighed raw materials to a high-speed mixer and dry-mix for 10-15 minutes. Then, add an appropriate amount of binder (such as a phosphate binder) and water and wet-mix for 15-20 minutes. The mixed slurry is passed through a spinning machine, where it is centrifugally spun into a tubular body. The formed body is placed in a drying chamber and dried at a low temperature (≤100°C) for 4-6 hours to ensure complete dryness. The dried body is then fired in a high-temperature kiln at a temperature between 1600-1700°C for approximately 6-8 hours. After firing, the material is slowly cooled to room temperature. During the cooling process, maintain a cooling rate of 100-150°C / hour to avoid cracks caused by thermal stress.

[0080] Erosion resistance: Erosion rate 0.18 mm / h (no CaMgB2O5 generation, Na + volatilization exacerbates erosion).

[0081] Thermal shock resistance: 19 cycles (1300℃ room temperature).

[0082] Glass liquid quality: bubble rate 0.6%.

[0083] 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 above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A highly corrosion-resistant pharmaceutical glass rotary tube, characterized by: The following components are included in parts by mass: Alumina: 70-80 parts; Zirconium oxide: 3-5 parts; Silicon oxide: 3-5 parts; Calcium oxide and magnesium oxide in total: 3-5 parts, wherein the molar ratio of calcium oxide to magnesium oxide is 1:1; Total of cerium oxide and yttrium oxide: 5 to 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 firstly pickled to remove surface sodium ions. When B2O3 is less than 10%, it is mixed with boron mud or H3BO3 calcined product to make B2O3 ≥ 10%. The molar content of Na2O in the waste borosilicate glass is calculated, and quicklime is added at a molar ratio of 1:1 to generate sodium calcium borate at high temperature to fix sodium. The waste borosilicate glass comprises, by mass, 70-85 parts of SiO2; 8-12 parts of B2O3; 3-10 parts of Na2O and / or K2O; 0-5 parts of Al2O3; and 0-3 parts of CaO.

2. The highly corrosion-resistant pharmaceutical glass rotary tube according to claim 1, characterized in that: Waste borosilicate glass is pickled with 5%-10% HNO3.

3. The highly corrosion-resistant pharmaceutical glass rotary tube according to claim 1, characterized in that: The particle size of alumina is 2-8 μm.

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

5. The highly corrosion-resistant pharmaceutical glass rotary tube according to claim 1, characterized in that: The silica particle size is 2-8 μm.

6. The highly corrosion-resistant pharmaceutical glass rotary tube according to claim 1, characterized in that: The particle size of calcium oxide and magnesium oxide is 2-8 μm.

7. The highly corrosion-resistant pharmaceutical 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 highly corrosion-resistant pharmaceutical 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 to 8, characterized in that: The steps include: Waste borosilicate glass is acid-washed to remove surface sodium ions. When B2O3 is less than 10%, boron mud or H3BO3 calcined product is added to make B2O3 ≥ 10%. The molar content of Na2O in the waste borosilicate glass is calculated, and quicklime is added at a molar ratio of 1:1 to generate sodium calcium borate at high temperature to fix sodium. Grinding the waste borosilicate glass that has been acid-washed and sodium-solidified into powder; Add 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 and dry-mix for 10-15 minutes. Then add phosphate binder and water and wet-mix for 15-20 minutes. Pass the mixed slurry through a spinning machine and spin it into a cylindrical body using centrifugal force. Place the formed green body in a drying chamber for low-temperature drying for 4-6 hours; The dried green body is placed in a high temperature kiln for firing at a temperature between 1600-1700°C for 6-8 hours; After sintering, the mixture was cooled to room temperature at a cooling rate of 100-150°C / hour.