A vacuum heat-collecting outer glass tube and preparation method thereof

Abstract

The present invention relates to the technical field of vacuum heat collector outer glass tubes, and relates to a vacuum heat collector outer glass tube and a preparation method thereof. The outer glass tube is formed by sealing a molybdenum glass group, a 3# glass and a 4.0 glass tube in sequence with a Kovar alloy ring; the thermal expansion coefficient of the Kovar alloy ring is 4.8 to 4.9×10 ‑6 / ℃, the thermal expansion coefficient of molybdenum glass group is 4.7~4.8×10 ‑6 / ℃, the thermal expansion coefficient of 3# glass is 4.45~4.55×10 ‑6 / ℃, the thermal expansion coefficient of 4.0 glass tube is 4.0×10 ‑6 / ℃, the outer glass tube only needs to be sealed 3 times during the sealing process, reducing the number of sealing times of 2 stages, doubling the sealing efficiency, and the Kovar alloy ring does not need to be machined with thin edges, reducing the difficulty and cost of sealing. At the same time, the matching sealing of 4J29 Kovar and molybdenum group glass eliminates the structural stress after annealing and reduces the hidden danger of vacuum failure. It solves the problems of many types of transition glass, many sealing times, complicated processes, low production efficiency, hidden dangers of vacuum aging, high sealing difficulty and high processing cost in the prior art.

Description

Technical Field

[0001] The invention relates to the technical field of vacuum heat-collecting outer glass tubes, in particular to a vacuum heat-collecting outer glass tube and a preparation method thereof. Background Art

[0002] Metal-glass flame sealing is the main method for producing outer glass tubes for vacuum collectors. At present, there are two main methods for preparation, namely, using 4J29 Kovar alloy to seal three kinds of transition glass in sequence and then flame sealing with 3.3 borosilicate glass to form an outer glass tube. The sealing needs to be carried out according to the gradient of the expansion coefficient. Therefore, when preparing the outer glass tube, many types of transition glass are required, the sealing times are many, the process is cumbersome, and the production efficiency is low. Alternatively, a 4J29 Kovar alloy with an expansion coefficient of 4.0×10 -6 / ℃ new constant expansion alloy and glass expansion coefficient is 4.0×10 -6 / ℃ glass tube is flame-sealed into an outer glass tube. Although this method reduces the types of transition glass and reduces the number of sealing times, the new constant expansion alloy has a narrow temperature range for matching the glass expansion curve, the structural stress of the sealed part is large after annealing, and there is a risk of vacuum failure. At the same time, the sealing Kovar alloy ring needs to be machined with a thin edge, which makes sealing difficult and the processing cost high. Summary of the invention

[0003] In view of the problems in the prior art such as many types of transition glass, many sealing times, complicated processes, low production efficiency, hidden dangers of vacuum aging, great sealing difficulty and high processing cost, the present invention provides a vacuum solar collector outer glass tube and a preparation method thereof.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] The present invention provides a vacuum heat-collecting outer glass tube, comprising a Kovar alloy ring, wherein the Kovar alloy ring is sequentially sealed with a molybdenum glass group, a 3# glass and a 4.0 glass tube; wherein the thermal expansion coefficient of the Kovar alloy ring is 4.8 to 4.9×10 -6 / ℃, the thermal expansion coefficient of molybdenum glass group is 4.7~4.8×10 -6 / ℃, the thermal expansion coefficient of 3# glass is 4.45~4.55×10 -6 / ℃, the thermal expansion coefficient of 4.0 glass tube is 4.0×10 -6 / ℃.

[0006] Furthermore, the 3# glass includes the following raw material components by weight: 67% to 71% SiO2, 18% to 25% B2O3, 3% to 5% ZnO, 2% to 4% Na2O, 1% to 3% Al2O3 and 0.1% to 0.5% Li2O.

[0007] Preferably, the Kovar alloy ring is 4J29 Kovar alloy.

[0008] Preferably, flame processing and sealing are adopted between the Kovar alloy ring and the molybdenum glass group, between the molybdenum glass group and 3# glass, and between 3# glass and 4.0 glass tube.

[0009] The method for preparing the above-mentioned vacuum heat collection outer glass tube comprises the following steps:

[0010] S1: hydrogen burning treatment of the Kovar alloy ring;

[0011] S2: preheating the molybdenum glass group and the hydrogen-burned Kovar alloy ring, and performing flame sealing treatment;

[0012] S3: flame-seal the molybdenum glass group sealed with the Kovar alloy ring with 3# glass and 4.0 glass tube in turn to form a vacuum heat collection outer glass tube;

[0013] S4: Annealing the vacuum solar collector outer glass tube after the sealing process, thus completing the preparation of the vacuum solar collector outer glass tube.

[0014] Furthermore, the hydrogen burning treatment temperature in S1 is 800-1300°C.

[0015] Furthermore, in S4, the annealing temperature is 510° C., and the annealing time is 35 to 45 min.

[0016] Furthermore, the annealing heating rate in S4 is 4-6°C / min, and the annealing cooling rate in S4 is 1-4°C / min.

[0017] Preferably, the flame sealing treatment in S2 or S3 is carried out under the conditions of natural gas sealing, with a flame temperature between 780 and 830° C. and a sealing time of 2 to 3 minutes.

[0018] Preferably, the flame sealing treatment in S2 or S3 is carried out by sealing by combustion of hydrogen and oxygen, with a flame temperature between 850 and 890° C. and a sealing time of 1 to 2 min.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention discloses a vacuum heat collection outer glass tube, wherein the outer glass tube is formed by sealing a molybdenum glass group, a 3# glass and a 4.0 glass tube in sequence with a Kovar alloy ring; the thermal expansion coefficient of the Kovar alloy ring is 4.8 to 4.9×10 -6 / ℃, the thermal expansion coefficient of molybdenum glass group is 4.7~4.8×10 -6 / ℃, the thermal expansion coefficient of 3# glass is 4.45~4.55×10 -6 / ℃, the thermal expansion coefficient of 4.0 glass tube is 4.0×10-6 / ℃, the outer glass tube only needs to be sealed 3 times during the sealing process, reducing the number of sealing times in 2 stages, doubling the sealing efficiency, and the Kovar alloy ring does not need to be machined with a thin edge, reducing the difficulty and cost of sealing. At the same time, the matching sealing of 4J29 Kovar and molybdenum group glass eliminates the structural stress after annealing and reduces the risk of vacuum failure.

[0021] The application of 3# glass can ensure that the outer glass tube has good chemical stability, light transmittance and sealing matching while meeting the required thermal expansion coefficient of the outer glass tube, and can also reduce the melting temperature of the glass.

[0022] The present invention also provides a method for preparing the above-mentioned vacuum heat collection outer glass tube, which only requires hydrogen burning treatment of the Kovar alloy ring; then preheating the molybdenum glass group and the Kovar alloy ring after hydrogen burning, and flame processing and sealing treatment, and then flame sealing treatment is performed on the molybdenum glass group after the Kovar alloy ring sealing treatment, the molybdenum glass group, 3# glass and 4.0 glass tube in turn, to make the vacuum heat collection outer glass tube; finally, annealing the vacuum heat collection outer glass tube after the sealing treatment, that is, the preparation of the vacuum heat collection outer glass tube is completed. The sealing process is simple, the skill requirements are reduced, and the sealing efficiency is improved. The original 5-pass transition sealing is changed to only 3-pass sealing, and the production efficiency is increased to 2 times; the sealed product is safe and reliable, the product life is long, and the mechanical strength and light transmission performance of the sealing part are good. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of a vacuum solar collector outer glass tube of the present invention.

[0024] Figure 2 The present invention is a flow chart of the method for preparing the vacuum solar collector outer glass tube.

[0025] Among them, 1-Kovar alloy ring, 2-Molybdenum glass group, 3-3# glass, 4-4.0 glass tube. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0029] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0030] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0031] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0033] The present invention discloses a vacuum heat collecting outer glass tube, referring to Figure 1 , comprising a Kovar alloy ring 1, wherein the Kovar alloy ring 1 sequentially seals the molybdenum glass group 2, the 3# glass 3 and the 4.0 glass tube 4; wherein the Kovar alloy ring 1 is 4J29 Kovar alloy, and the thermal expansion coefficient of the Kovar alloy ring 1 is 4.8-4.9×10 -6 / ℃, the thermal expansion coefficient of molybdenum glass group 2 is 4.7~4.8×10 -6 / ℃, the thermal expansion coefficient of 3# glass 3 is 4.45~4.55×10 -6 / ℃, the thermal expansion coefficient of 4.0 glass tube 4 is 4.0×10 -6 / ℃. The Kovar alloy ring 1, the molybdenum glass group 2 and the 3# glass 3 are symmetrically distributed along the 4.0 glass tube 4. Preferably, the Kovar alloy ring 1 and the molybdenum glass group 2, the molybdenum glass group 2 and the 3# glass 3, and the 3# glass 3 and the 4.0 glass tube 4 are all sealed by flame processing.

[0034] The 3# glass 3 comprises the following raw material components: 67-71% SiO2, 18-25% B2O3, 3-5% ZnO, 2-4% Na2O, 1-3% Al2O3 and 0.1-0.5% Li2O. The preparation method is as follows: after mixing the above raw materials in proportion, heat preservation at 1150-1250°C for 4-6 hours, then heating to 1395-1415°C at a rate of 0.3-1°C / min for melting until the raw materials are completely melted to form glass liquid, finally clarifying at 1250-1350°C for 30-40 hours, blowing at 1150-1250°C, annealing at 540-560°C for 2-3 hours, and obtaining the 3# glass 3.

[0035] See also Figure 2 The present invention provides a method for preparing the above-mentioned vacuum solar collector outer glass tube, comprising the following steps:

[0036] S1: performing hydrogen burning treatment on the Kovar alloy ring 1, and the hydrogen burning treatment temperature is 800-1300°C;

[0037] S2: Preheat the molybdenum glass group 2 and the hydrogen-burned Kovar alloy ring 1, and perform flame processing and sealing treatment; wherein, the conditions for medium flame sealing treatment are: natural gas sealing, flame temperature between 780 and 830°C, sealing time 2 to 3 minutes, or hydrogen and oxygen combustion sealing for flame sealing treatment, flame temperature between 850 and 890°C, sealing time 1 to 2 minutes.

[0038] S3: flame-seal the molybdenum glass group 2 sealed with the Kovar alloy ring 1 with the 3# glass 3 and the 4.0 glass tube 4 in turn to form a vacuum collector outer glass tube; wherein, the conditions for the medium flame sealing treatment are: natural gas sealing, the flame temperature is between 780 and 830°C, and the sealing time is 2 to 3 min, or hydrogen and oxygen combustion is used for flame sealing, the flame temperature is between 850 and 890°C, and the sealing time is 1 to 2 min.

[0039] S4: Annealing the vacuum solar collector outer glass tube after the sealing treatment, that is, completing the preparation of the vacuum solar collector outer glass tube, wherein the annealing heating rate is 4-6°C / min, the annealing temperature is 510°C, the annealing time is 35-45 min, and the annealing cooling rate is 1-4°C / min.

[0040] In summary, the present invention provides a vacuum heat collection outer glass tube and a preparation method thereof, wherein the outer glass tube is formed by sequentially sealing the molybdenum glass group 2, the 3# glass 3 and the 4.0 glass tube 4 with a Kovar alloy ring 1; during the sealing process, the outer glass tube only needs to be sealed 3 times, reducing the number of sealing times of 2 sections, doubling the sealing efficiency, and the Kovar alloy ring does not need to be machined with a thin edge, reducing the sealing difficulty and cost. At the same time, the matching sealing of the 4J29 Kovar and the molybdenum group glass eliminates the structural stress after annealing and reduces the hidden danger of vacuum failure.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and substitutions, and these modifications and substitutions are also within the scope of protection covered by the claims.

Claims

1. A vacuum solar collector outer glass tube, characterized in that: The invention comprises a Kovar alloy ring (1), wherein the Kovar alloy ring (1) is sequentially sealed with a molybdenum glass group (2), a 3# glass (3) and a 4.0 glass tube (4); wherein the thermal expansion coefficient of the Kovar alloy ring (1) is 4.8 to 4.9×10 -6 / ℃, the thermal expansion coefficient of the molybdenum glass group (2) is 4.7~4.8×10 -6 / ℃, the thermal expansion coefficient of 3# glass (3) is 4.45~4.55×10 -6 / ℃, the thermal expansion coefficient of the 4.0 glass tube (4) is 4.0×10 -6 / ℃; wherein the 3# glass (3) comprises the following raw material components by weight: 67% to 71% SiO2, 18% to 25% B2O3, 3% to 5% ZnO, 2% to 4% Na2O, 1% to 3% Al2O3 and 0.1% to 0.5% Li2O; the Kovar alloy ring is 4J29 Kovar alloy; Flame processing and sealing are used between the Kovar alloy ring (1) and the molybdenum glass group (2), between the molybdenum glass group (2) and the 3# glass (3), and between the 3# glass (3) and the 4.0 glass tube (4). The flame sealing treatment conditions are: natural gas sealing, and the flame temperature is between 780 and 830°C.

2. The method for preparing the vacuum solar collector outer glass tube according to claim 1, characterized in that: The following steps are involved: S1: performing hydrogen burning treatment on the Kovar alloy ring (1); S2: preheating the molybdenum glass group (2) and the hydrogen-burned Kovar alloy ring (1), and performing flame sealing treatment; S3: flame-sealing the molybdenum glass group (2) after the sealing treatment with the Kovar alloy ring (1) with the 3# glass (3) and the 4.0 glass tube (4) in sequence to produce a vacuum heat collection outer glass tube; S4: Annealing the vacuum solar collector outer glass tube after the sealing process, thus completing the preparation of the vacuum solar collector outer glass tube.

3. The method for preparing the vacuum solar collector outer glass tube according to claim 2, characterized in that: The hydrogen treatment temperature in S1 is 800-1300°C.

4. The method for preparing the vacuum solar collector outer glass tube according to claim 3, characterized in that: In S4, the annealing temperature is 510°C and the annealing time is 35 to 45 min.

5. The method for preparing the vacuum solar collector outer glass tube according to claim 2, characterized in that: The annealing heating rate in S4 is 4-6°C / min, and the annealing cooling rate in S4 is 1-4°C / min.

6. The method for preparing the vacuum solar collector outer glass tube according to any one of claims 2 to 5, characterized in that: The flame sealing treatment conditions in S2 or S3 are: natural gas sealing, flame temperature between 780 and 830°C, and sealing time of 2 to 3 minutes.

7. The method for preparing the vacuum solar collector outer glass tube according to any one of claims 2 to 5, characterized in that: The flame sealing treatment conditions in S2 or S3 are: flame sealing treatment is carried out by burning hydrogen and oxygen, the flame temperature is between 850 and 890°C, and the sealing time is 1 to 2 minutes.

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