Method for testing the erosion resistance of a rotating tube

Abstract

This invention discloses a test method for the corrosion resistance of rotating tubes, belonging to the field of analytical testing technology. The test method is as follows: The rotating tube is at least partially inserted into molten glass and heated and held at that temperature; the rotating tube is then lifted from the surface of the molten glass, and the molten glass adhering to the end of the rotating tube forms a glass droplet. This glass droplet is then broken off from the end of the rotating tube, and the broken glass droplet is used as an analytical sample. The corrosion resistance of the rotating tube is determined based on the inclusions and bubbles in the analytical sample. This invention's test method is simple, low-cost, and highly accurate. It can also pre-screen high-quality rotating tubes with strong corrosion resistance, reducing the number of downtime replacements caused by peeling and bubbles during production, and improving the continuity and yield of glass tube drawing production lines.

Description

Technical Field

[0001] This invention relates to the field of analytical testing technology, and in particular to a method for testing the corrosion resistance of a rotating tube. Background Technology

[0002] Rotary tubes are important refractory material components in glass tube drawing systems. They come into direct contact with molten glass, and their performance directly affects the output and quality of glass tubes, as well as the overall value and efficiency of the glass tube production line.

[0003] During actual use, rotating tubes undergo phase transformation under high-temperature conditions. This phase transformation process leads to changes in the volume and porosity of the rotating tube, which intensifies the penetration of molten glass into the rotating tube, promoting erosion and peeling. This results in problems such as faster periodic replacement, longer downtime and impact time, increased replacement and maintenance costs, and discontinuous glass tube production, all of which have many adverse effects on improving the quality of glass tubes. Therefore, it is necessary to test and analyze the erosion resistance of rotating tubes.

[0004] Currently, the test method for the erosion resistance of refractory materials is "Test Method for Static Resistance of Refractory Materials for Glass Melting Furnaces to Molten Glass". The specific test process is to characterize the erosion resistance of refractory materials by measuring the amount of erosion at the liquid surface where the refractory material and molten glass come into contact.

[0005] However, actual experiments have shown that the corrosion of rotating tubes is mainly manifested by stone spalling and bubble formation. The corrosion at the liquid surface where the refractory material and the molten glass come into contact is not suitable for characterizing this type of rotating tube. Therefore, it is urgent to develop a test method that can determine the corrosion resistance of rotating tubes characterized by stone spalling and bubble formation to fill the gap in this field. Summary of the Invention

[0006] The main objective of this invention is to provide a test method for the corrosion resistance of rotating tubes, which solves the technical problem that existing test methods for the corrosion resistance of refractory materials are not applicable to testing rotating tubes, and allows for convenient and clear observation of the corrosion resistance of rotating tubes.

[0007] To achieve the above objectives, the present invention provides a method for testing the corrosion resistance of a rotating tube, comprising the following steps: (a) Insert the rotating tube at least partially into the molten glass and heat and hold it at that temperature; (b) The rotating tube is lifted from the molten glass, and the molten glass adhering to the end of the rotating tube forms a glass droplet. The glass droplet is then broken off from the end of the rotating tube. The broken glass droplet is used as an analytical sample, and the corrosion resistance of the rotating tube is determined based on the stones and bubbles in the analytical sample.

[0008] In some embodiments of the present invention, the material of the rotating tube includes corundum mullite.

[0009] In some embodiments of the present invention, the rotating tube is strip-shaped.

[0010] In some embodiments of the present invention, the rotating tube is immersed in the molten glass at 1 / 3 to 1 / 2 of its length from the end.

[0011] In some embodiments of the present invention, in step (a), glass is placed in a container and heated to form the molten glass, wherein: The glass includes borosilicate glass.

[0012] In some embodiments of the present invention, the dimensions of the container are: outer diameter 60±0.5mm, inner diameter 50±0.5mm, and height 55±0.5mm; And / or, the container is made of quartz.

[0013] In some embodiments of the present invention, the heating and heat preservation temperature is 1300℃~1400℃; And / or, the heating and heat preservation time is 100h~120h; And / or, the heating and heat preservation rate is 3℃ / min to 5℃ / min.

[0014] In some embodiments of the present invention, the corrosion resistance of the rotating tube is determined based on the number and size of the stones and the number and size of the bubbles.

[0015] In some embodiments of the present invention, the erosion resistance level is classified according to the number and size of the stones and the number and size of the bubbles, and arranged in descending order of erosion resistance performance as Level 1, Level 2, Level 3, and Level 4: Level 1: No stones, no air bubbles; Level 2: The number of air bubbles is less than 3, the diameter of the stones is less than 0.3 mm, and the number of stones is less than 3. Level 3: A string of stones appears; Grade IV: The diameter of the stone is 0.7 mm or more, and the number of air bubbles is 3 or more.

[0016] In some embodiments of the present invention, the length of the glass droplet is 20 mm to 30 mm; and / or, 1 / 6 to 1 / 3 of the length of the glass droplet from the broken end is used as the analytical sample.

[0017] The beneficial effects that this invention can achieve are: This invention involves immersing a rotating tube partially into molten glass. Depending on its corrosion resistance, the rotating tube will dissolve some of its structure into the molten glass to varying degrees. After being heated and held at a certain temperature in the molten glass for a period of time, the rotating tube is lifted out of the molten glass, forming a glass droplet at its end. The glass droplet and the rotating tube are then separated. The corrosion resistance of the rotating tube is determined by analyzing the inclusions and bubbles in the glass droplet. Compared with the traditional method that only measures the amount of corrosion at the liquid surface, this method is suitable for rotating tubes made of materials where partial tissue peeling and bubble formation are used as corrosion characteristics, such as rotating tubes made of corundum mullite.

[0018] Moreover, the testing method of this invention is simple, low-cost, and highly accurate. It can also screen out high-quality rotating tubes with strong corrosion resistance in advance, reduce the number of downtime replacements caused by peeling and bubbles in the production process, and improve the continuity of glass tube drawing production lines and the yield of finished products. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of a rotating tube being inserted vertically into molten glass in an embodiment of the present invention; Figure 2 This is a schematic diagram of a glass wire formed at the end of a rotating tube according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the glass wire being separated from the end of the rotating tube according to an embodiment of the present invention; Figure 4 This is a microscopic image of the analytical sample of group 1 in Embodiment 1 of the present invention; Figure 5 This is a microscopic image of the analytical sample of group 2 in Example 1 of the present invention; Figure 6 This is a microscopic image of the analytical sample of group 3 in Example 1 of the present invention; Figure 7 This is a microscopic image of the analytical sample of group 4 in Example 1 of the present invention.

[0021] Explanation of icon numbers: 10. Rotating tube; 20. Molten glass; 21. Glass droplet; 211. Stone; 212. Bubble.

[0022] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0023] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] In this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Furthermore, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. If the combination of technical solutions is contradictory or impossible to implement, such a combination should be considered non-existent and not within the scope of protection claimed by this invention.

[0026] This invention provides a method for testing the corrosion resistance of a rotating tube, comprising the following steps: (a) Reference Figure 1 The rotating tube 10 is at least partially inserted into the molten glass 20 and heated and kept at that temperature. (b) Refer to Figure 1 , Figure 2 and Figure 3 The rotating tube 10 is lifted from the molten glass 20, and the molten glass 20 adhering to the end of the rotating tube 10 forms a glass droplet 21. The glass droplet 21 is then broken off from the end of the rotating tube 10. The broken glass droplet 21 is used as an analysis sample, and the corrosion resistance of the rotating tube is judged based on the stones 211 and bubbles 212 in the analysis sample.

[0027] In this invention, a rotating tube refers to a type of hollow refractory tube with equal wall thickness and closed at one end in the glass tube drawing process. During operation, it rotates continuously around its axis and is partially immersed in molten glass. The molten glass is drawn into a tubular product by centrifugal force and traction force.

[0028] The principle of the rotating tube corrosion resistance test method of the present invention is as follows: The rotating tube is partially immersed in molten glass and heated and kept at that temperature for a period of time. The immersed part will be corroded to different degrees due to the different corrosion resistance of the rotating tube. The stones and bubbles produced by the corrosion will dissolve into the glass liquid near the wall of the rotating tube. The rotating tube is lifted out of the molten glass. The glass liquid adhering to the wall of the rotating tube will slowly form glass droplets under the influence of gravity and air cooling, carrying the dissolved stones and bubbles. The glass droplets are separated from the rotating tube. By analyzing the stones and bubbles in the glass droplets, the corrosion resistance of the rotating tube can be determined.

[0029] Compared to traditional methods that only measure the amount of erosion at the liquid level, the testing method of this invention is applicable to rotating tubes made of materials characterized by partial tissue peeling and bubble formation, such as rotating tubes made of corundum-mullite. Furthermore, the testing method of this invention is simple, low-cost, and highly accurate. It can also pre-screen high-quality rotating tubes with strong erosion resistance, reducing the number of downtime replacements caused by peeling and bubbles during production, and improving the continuity and yield of glass tube drawing production lines.

[0030] In some embodiments, the rotating tube is made of corundum mullite. Rotating tubes made of ordinary materials exhibit significant corrosion at the molten glass interface. The corrosion resistance of the rotating tube can be determined by measuring the difference in corrosion resistance before and after corrosion at the molten glass interface according to the "Test Method for Static Resistance of Refractory Materials for Glass Melting Furnaces." However, materials like corundum mullite do not readily show significant corrosion at the molten glass interface; their corrosion is mainly manifested in the shedding of the rotating tube structure and the formation of bubbles. Therefore, by using the test method of this invention to analyze the stones and bubbles that detach into the glass wire, the corrosion resistance of rotating tubes made of this material can be determined.

[0031] Rotating tubes are typically large, making it inconvenient to test the entire tube. Since the outer wall of the rotating tube is in contact with the molten glass, the outer wall can be selected as a test sample. This not only facilitates operation but also makes the test results more convincing.

[0032] In some embodiments, the rotating tube is shaped like a strip. Strip-shaped test samples are more likely to allow molten glass to converge at the end and form glass droplets. Moreover, they are easier to retain impurities such as stones and bubbles generated during the erosion process.

[0033] In some embodiments, the rotating tube is rectangular in shape.

[0034] In some embodiments, the rotating tube has dimensions of 50±0.5mm×10±0.5mm×10±0.5mm. The elongated test sample allows the molten glass to easily gather at the end and form glass droplets. Moreover, the test can be completed with fewer samples, saving resources.

[0035] In some embodiments, one-third to one-half of the rotating tube is immersed in the molten glass from its end. It is understood that the end of the rotating tube refers to the end facing the molten glass.

[0036] In some embodiments, in step (a), the rotating tube is inserted at least partially vertically into the molten glass. This eliminates the influence of factors such as bending or tilting of the rotating tube on the test results. Moreover, when the rotating tube is lifted, it is easy to form glass droplets at the end of the rotating tube. At the same time, impurities such as stones and bubbles dissolved in the glass droplets are effectively retained.

[0037] In some embodiments, in step (b), the rotating tube is lifted from a direction perpendicular to the liquid surface of the molten glass. This can eliminate the influence of factors such as bending or tilting of the rotating tube on the test results. Moreover, when the rotating tube is lifted, it is easy to form glass droplets at the end of the rotating tube. At the same time, impurities such as stones and bubbles dissolved in the glass droplets are effectively retained.

[0038] In some embodiments, a groove can be made at the end of the rotating tube away from the molten glass. The rotating tube is suspended and partially immersed in the molten glass through the groove, so that the rotating tube remains perpendicular to the surface of the molten glass during the test, eliminating the influence of factors such as bending or tilting of the rotating tube on the test results.

[0039] In some embodiments, in step (a), glass is placed in a container, a rotating tube is suspended directly above the bottom of the container, the glass is heated to molten glass, and the rotating tube is at least partially inserted into the molten glass, and heating is continued and maintained at that temperature. It is understood that the glass referred to here is solid glass that has not yet melted.

[0040] In some embodiments, the heating rate is 8°C / min to 12°C / min, and may be 10°C / min.

[0041] In some embodiments, the rotating tube is suspended vertically directly above the bottom of the container without contacting the container, allowing molten glass to encase the entire end of the rotating tube and collect stones that have detached due to erosion and the resulting bubbles.

[0042] In some embodiments, the glass includes borosilicate glass, which has moderate corrosion resistance and can identify the dividing point of the corrosion resistance of the rotating tube, preventing inaccurate judgment of the corrosion resistance of the rotating tube due to excessively strong or weak corrosion resistance of the glass.

[0043] In some embodiments, the glass comprises borosilicate glass.

[0044] In this invention, the average particle size of the glass can be appropriately adjusted according to the size of the rotating tube and the container. In some embodiments, the average particle size of the glass is ≤2mm, and can be 2mm, 1mm, 0.5mm, 0.1mm, etc. The glass can be melted quickly and uniformly to obtain molten glass, reducing the impact of impurities such as extra bubbles generated in the glass droplets due to uneven melting caused by excessively large glass particle size, which affects the accuracy of the test results.

[0045] In this invention, the weight of the glass can be appropriately adjusted according to the size of the rotating tube and the container, preferably to submerge a portion of the rotating tube. In some embodiments, the weight of the glass is 55g to 65g, which is suitable for small-volume test samples and can save materials.

[0046] The size of the container can be adjusted according to the size of the rotating tube so that the rotating tube can be partially immersed in the molten glass. In some embodiments, the container dimensions are an outer diameter of 60±0.5 mm, an inner diameter of 50±0.5 mm, and a height of 55±0.5 mm.

[0047] In some embodiments, the container includes a crucible.

[0048] In some embodiments, the crucible is made of quartz.

[0049] In some embodiments, the heating and holding temperature is 1300℃~1400℃, which can be 1300℃, 1330℃, 1350℃, 1360℃, 1380℃, 1400℃, etc. Under the above heating and holding conditions, the temperature of molten glass flowing through the rotating tube during the production process can be simulated, and the rotating tube itself is less likely to break due to excessively high heating and holding temperatures.

[0050] In some embodiments, the heating and holding time is 100h~120h, which can be 100h, 103h, 105h, 108h, 110h, 115h, 118h, 119h, 120h, etc. Within the above heating and holding time, the dividing point of the erosion resistance performance of the rotating tube can be identified, preventing the heating and holding time from being too short or too long, which would affect the accuracy of the test.

[0051] In some embodiments, the heating and holding time is calculated from the moment the rotating tube is partially immersed in the molten glass, which facilitates the analysis of the rotating tube's corrosion resistance.

[0052] In some embodiments, the heating and heat preservation rate is 3°C / min to 5°C / min.

[0053] In this invention, reference Figure 2Glass droplets 21 refer to the glass liquid that adheres to the wall of the rotating tube 10 as the rotating tube 10 is lifted from the molten glass 20. This part of the glass liquid slowly forms glass droplets under the influence of gravity and air cooling as the rotating tube 10 is lifted.

[0054] In this invention, the bubbles generated in the glass droplet analysis object typically originate from: (1) fine particles eroded and detached from the rotating tube; and (2) gases generated by the chemical reaction of the tissue in the rotating tube being eroded by the glass liquid. The stones in the rotating tube refer to the parts of the rotating tube eroded and detached by the glass liquid. Therefore, the erosion resistance of the rotating tube can be accurately reflected by the bubbles appearing in the analysis object and the stones falling from the rotating tube.

[0055] In some embodiments, the corrosion resistance of the rotating tube is determined based on the number and size of precipitates and bubbles in the glass droplets. The fewer the number and the smaller the volume of precipitates and bubbles, the better the corrosion resistance of the rotating tube.

[0056] In some embodiments, the corrosion resistance of the rotating tube can be graded according to the number and size of stones and the number and size of bubbles in the glass droplets.

[0057] The erosion resistance level is determined based on the number and size of the stones and the number and size of the air bubbles, and is ranked from best to worst as Level 1, Level 2, Level 3, and Level 4. Level 1: No stones, no air bubbles; Level 2: The number of air bubbles is less than 3, the diameter of the stones is less than 0.3 mm, and the number of stones is less than 3. Level 3: A string of stones appears; Grade IV: The diameter of the stone is 0.7 mm or more, and the number of air bubbles is 3 or more.

[0058] In some embodiments, the length of the glass droplet is 20mm to 30mm.

[0059] In some embodiments, the length of the glass droplet from the broken end is used as the analysis sample. This ensures that erosion defects such as stones and bubbles have been fully analyzed and entered into the glass droplet for easy observation, while avoiding observation difficulties caused by being too close to the end or insufficient defects caused by being too far from the end, which would affect the accuracy of the test results.

[0060] The tail of a glass droplet typically forms a glass filament. In some embodiments, the formed glass filament can be cut off to facilitate observation of erosion defects.

[0061] In some embodiments, testing is performed using two or more rotating tubes to improve the accuracy of the test.

[0062] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following specific embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0063] Example 1 Prepare 4 sets of corundum mullite rotating tube samples: Use a cutting machine to cut the corundum mullite rotating tubes to obtain rotating tube samples. The size of the rotating tube samples is 50mm×10mm×10mm (error ±0.5mm). Use a diamond cutting machine to groove the rotating tube samples (mainly for sample suspension).

[0064] Prepare the container: Use a quartz crucible as the container. The crucible dimensions are: outer diameter 60mm, inner diameter 50mm, and height 55mm.

[0065] The test methods for the corrosion resistance of the four groups of rotating tubes in Example 1 are as follows: (a) A borosilicate glass shard with a particle size of less than 2 mm and a weight of 60 g is placed in a crucible and then placed in a combustion furnace. The rotating tube sample is vertically suspended above the bottom of the container through a groove. The borosilicate glass is then heated at a heating rate of 10 °C / min to melt the borosilicate glass and form molten glass. The rotating tube sample is then partially inserted vertically into the molten glass. The temperature is then increased to 1360 °C at a heating rate of 3 °C / min and held for 120 h.

[0066] (b) After the heat preservation is completed, the rotating tube sample is lifted from the direction perpendicular to the bottom of the crucible. The molten glass adhering to the end of the rotating tube sample forms a glass droplet of about 30 mm in length. The glass droplet is broken off from the end of the rotating tube sample. The broken glass droplet is used as the analysis sample. The corrosion resistance of the rotating tube is judged based on the stones and bubbles in the analysis sample.

[0067] Results analysis: A 5mm length from the broken end of the glass droplet was used as the analysis sample. The number and size of stones and bubbles in the sample were observed and analyzed under a microscope. The fewer and smaller the number and size of stones and bubbles, the better the corrosion resistance. The corrosion resistance levels were divided into four grades from best to worst: Grade 1, Grade 2, Grade 3, and Grade 4. Level 1: No stones, no air bubbles; Level 2: The number of air bubbles is less than 3, the diameter of the stones is less than 0.3 mm, and the number of stones is less than 3. Level 3: A string of stones appears; Grade IV: The diameter of the stone is 0.7 mm or more, and the number of air bubbles is 3 or more.

[0068] Microscopic images are shown below. Figures 4 to 7The condition of stones and air bubbles is summarized in Table 1, and the actual number of days of use of the samples in the four groups were tested respectively.

[0069] Table 1

[0070] As shown in Table 1, the corrosion resistance obtained from the test, arranged from strongest to weakest, are group 1, group 2, group 3, and group 4. In terms of actual usage days, the usage days, arranged from most to least, are group 1, group 2, group 3, and group 4, which are consistent with the test results. It can be seen that the test method for the corrosion resistance of the rotating tube of the present invention is accurate and feasible.

[0071] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A method for testing the corrosion resistance of a rotating tube, characterized in that, Includes the following steps: (a) Insert the rotating tube at least partially into the molten glass and heat and hold it at that temperature; (b) The rotating tube is lifted from the molten glass, and the molten glass adhering to the end of the rotating tube forms a glass droplet. The glass droplet is then broken off from the end of the rotating tube. The broken glass droplet is used as an analytical sample, and the corrosion resistance of the rotating tube is determined based on the stones and bubbles in the analytical sample.

2. The test method for the corrosion resistance of the rotating tube according to claim 1, characterized in that, The rotating tube is made of corundum mullite.

3. The test method for the corrosion resistance of the rotating tube according to claim 1, characterized in that, The rotating tube may be strip-shaped.

4. The test method for the corrosion resistance of a rotating tube according to claim 1, characterized in that, The rotating tube is immersed in the molten glass for 1 / 3 to 1 / 2 of its length from the end; and / or, in step (a), the rotating tube is inserted into the molten glass at least partially perpendicularly; and / or, in step (b), the rotating tube is lifted from a direction perpendicular to the liquid surface of the molten glass.

5. The test method for the corrosion resistance of the rotating tube according to claim 1, characterized in that, In step (a), glass is placed in a container and heated to form the molten glass, wherein: The glass includes borosilicate glass.

6. The test method for the corrosion resistance of the rotating tube according to claim 1, characterized in that, The dimensions of the container are: outer diameter 60±0.5mm, inner diameter 50±0.5mm, and height 55±0.5mm; And / or, the container is made of quartz.

7. The test method for the corrosion resistance of the rotating tube according to claim 1, characterized in that, The heating and heat preservation temperature is 1300℃~1400℃; And / or, the heating and heat preservation time is 100h~120h; And / or, the heating and heat preservation rate is 3℃ / min to 5℃ / min.

8. The test method for the corrosion resistance of the rotating tube according to claim 1, characterized in that, The corrosion resistance of the rotating tube is determined based on the number and size of the stones and the number and size of the bubbles.

9. The test method for the corrosion resistance of the rotating tube according to claim 8, characterized in that, The erosion resistance level is determined based on the number and size of the stones and the number and size of the air bubbles, and is ranked from best to worst as Level 1, Level 2, Level 3, and Level 4. Level 1: No stones, no air bubbles; Level 2: The number of air bubbles is less than 3, the diameter of the stones is less than 0.3 mm, and the number of stones is less than 3. Level 3: A string of stones appears; Grade IV: The diameter of the stone is 0.7 mm or more, and the number of air bubbles is 3 or more.

10. The test method for the corrosion resistance of the rotating tube according to any one of claims 1 to 9, characterized in that, The length of the glass droplet is 20mm to 30mm; and / or, 1 / 6 to 1 / 3 of the length of the glass droplet from the broken end is used as the analytical sample.

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