Preparation method of polycrystalline aluminum oxide pipe composite structure

Abstract

The invention provides a preparation method of a polycrystalline aluminum oxide pipe composite structure. The preparation method comprises the steps that a polycrystalline aluminum oxide main pipe layer is sintered and formed, the outer surface of the polycrystalline aluminum oxide main pipe layer is roughened, and a rough attachment surface is formed; preparing a transition layer containing a stepped tooth and stepped groove structure on the outer side of the polycrystalline aluminum oxide main pipe layer; a connecting layer is prepared on the transition layer, and punching positions corresponding to the stepped grooves are marked; a punching position is selected according to the connecting position, a surface hole is machined, and the surface hole goes deep into the stepped groove; and installing a metal riveting piece on the selected surface hole. The method has the advantages of mature and easy-to-implement preparation process, simple device structure, firm connection, stable arrangement of the metal riveting piece, light and thin overall device structure and the like.

Description

Technical Field

[0001] The present invention relates to a method for preparing a composite structure of polycrystalline alumina pipes, belonging to the technical field of alumina pipe equipment manufacturing. Background Art

[0002] Alumina pipes are pipes prepared by sintering with alumina as the main body, and have the characteristics of high hardness, high temperature resistance and light weight, and are widely used in fields such as high-temperature equipment. However, alumina pipes are relatively brittle, and brittleness will become a defect in many scenarios, thus limiting the scope of application of alumina pipes.

[0003] Polycrystalline alumina pipes with a fine and uniform polycrystalline structure obtained through grain boundary optimization can improve various properties of the pipes under high-temperature conditions. In particular, the limit temperature of high-temperature resistance can be greatly improved. After verification, the corrosion resistance and other pipe properties of polycrystalline alumina pipes can also be better. However, its disadvantages are also very obvious. First, the preparation process is relatively complex. Through precise temperature control of gel injection molding and static pressure furnace sintering, its production cost is greatly increased. Second, its weight will also increase and its heat insulation performance is average. When used in high-temperature industrial fields such as crucible diversion growth furnaces and battery electrolyte pipes, affected by the thermal cycling and continuous use of the use environment, it will lead to a short service life due to surface cracking and crack propagation.

[0004] In the above high-temperature industrial scenarios, high-temperature lining pipes are commonly used functional lining components to protect the internal structure of equipment or pipelines. Its main function is heat insulation and resistance to thermal cycling. Therefore, further pursuing the use performance of alumina pipes under high-temperature environments is an ongoing application demand in the industry. Summary of the Invention

[0005] Aiming at the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a method for preparing a composite structure of polycrystalline alumina pipes.

[0006] According to an embodiment of the present invention, the first solution is provided as: A method for preparing a composite structure of polycrystalline alumina pipes, comprising the following steps:

[0007] Sinter and form a polycrystalline alumina main pipe layer and roughen its outer surface to form a rough attachment surface;

[0008] Prepare a transition layer with stepped teeth and stepped groove structures on the outside of the polycrystalline alumina main pipe layer;

[0009] Prepare a connection layer on the transition layer and mark the punching positions corresponding to the stepped grooves;

[0010] Select punching positions according to the connection positions and process surface holes, and the surface holes penetrate into the stepped grooves;

[0011] Install metal riveting parts on the selected surface holes.

[0012] Further, the steps of sintering and forming the polycrystalline alumina main pipe layer include:

[0013] Obtain a blank and incorporate 0.5 - 2 wt% of nano aluminum nitride. Gel-casting is used to form the main pipe blank of the doped blank, and sintering is carried out at 1700 - 1850 °C for a holding time of 2 - 5 hours.

[0014] Further, the steps of roughening the surface of the polycrystalline alumina main pipe layer and forming a rough attachment surface include:

[0015] The surface roughness of the polycrystalline alumina main pipe layer is polished to 3 - 500 um by sandblasting.

[0016] Further, the steps of preparing a transition layer with stepped teeth and stepped grooves on the outer side of the polycrystalline alumina main pipe layer include:

[0017] Weave alumina fibers or silicon carbide fibers into a shape, infiltrate with silica sol, and then wind or attach them to the outer side of the polycrystalline alumina main pipe layer. Axial stepped teeth and stepped grooves between the stepped teeth are formed by laser etching or die pressing. The height of the stepped teeth is 50 - 200 mm, the tooth pitch is 200 - 800 mm, and post-sintering treatment is carried out at 1500 - 1650 °C to fix the transition layer.

[0018] Further, the stepped teeth are serrated, trapezoidal or wavy, and 6 - 36 of them are evenly distributed along the outer side of the polycrystalline alumina main pipe layer.

[0019] Further, the steps of preparing a connection layer on the transition layer include:

[0020] Pour a mixed blank of alumina and mullite fibers on the outer side of the transition layer, and carry out secondary sintering and forming at 1500 - 1600 °C.

[0021] Further, the steps of marking the drilling positions corresponding to the stepped grooves include:

[0022] Cut the cross-section of the polycrystalline alumina main pipe layer including the multi-layer coating and the connection layer, and mark the drilling positions according to the screenshot of the cutting position.

[0023] Further, the steps of selecting the drilling positions according to the connection positions and processing the surface holes include:

[0024] Drill holes at the drilling positions of the connection layer, with a hole diameter of 0.1 - 5 mm. Ultrasonic vibration-assisted tapping is used to process internal threads in the drilled holes to obtain surface holes, and the thread depth is 0.5 - 1 times the hole diameter.

[0025] Further, the steps of installing metal rivets on the selected surface holes include:

[0026] The metal rivet includes a threaded connection part, a nut and a connecting rod. The metal rivet is fixed in the surface hole through the threaded connection part and fixed by diffusion welding, and the welding temperature is 800 - 1000 °C.

[0027] Furthermore, an aluminum oxynitride coating is deposited on the inner wall of the polycrystalline alumina main pipe layer by plasma spraying, and the coating thickness is 100 - 2000 um.

[0028] According to the implementation scheme of the present invention, using the preparation method of a polycrystalline alumina pipe composite structure in the first scheme provided by the present invention, the second scheme is as follows:

[0029] A polycrystalline alumina pipe composite structure includes the structure prepared by any of the above-mentioned polycrystalline alumina pipe composite structure preparation methods.

[0030] A computer device includes a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the processor performs the following steps:

[0031] Sinter and form the polycrystalline alumina main pipe layer and roughen its outer surface to form a rough attachment surface;

[0032] Prepare a transition layer with stepped teeth and stepped groove structures on the outside of the polycrystalline alumina main pipe layer;

[0033] Prepare a connection layer on the transition layer and mark the drilling positions corresponding to the stepped grooves;

[0034] Select the drilling positions according to the connection positions and process the surface holes, and the surface holes penetrate into the stepped grooves;

[0035] Install metal rivets on the selected surface holes.

[0036] A computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the processor performs the following steps:

[0037] Sinter and form the polycrystalline alumina main pipe layer and roughen its outer surface to form a rough attachment surface;

[0038] Prepare a transition layer with stepped teeth and stepped groove structures on the outside of the polycrystalline alumina main pipe layer;

[0039] Prepare a connection layer on the transition layer and mark the drilling positions corresponding to the stepped grooves;

[0040] Select the drilling positions according to the connection positions and process the surface holes, and the surface holes penetrate into the stepped grooves;

[0041] Install metal rivets on the selected surface holes.

[0042] Compared with the prior art, the beneficial effects of the independent claim of the technical solution provided by this application are as follows: In this method, a transition layer is attached to the outer side of the sintered and formed polycrystalline alumina main pipe layer. The outer shape of the transition layer includes stepped teeth and stepped groove structures. A connection layer is further prepared on the transition layer, and metal rivets are arranged on the surface holes of the connection layer. The positions of the surface holes correspond to those of the stepped grooves. The metal rivets have a certain connection depth. Therefore, the thickness of the connection layer needs to be set relatively thick. However, in this case, the stepped grooves can provide a depth space for installing the metal rivets, and the overall connection layer can be set thinner without reducing the connection surface between the connection layer and the transition layer. It has the advantages of mature and easy-to-implement preparation process, simple device structure, firm connection, stable setting of metal rivets, and light and thin overall device structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0044] Among them:

[0045] Figure 1 is a flowchart of a method for preparing a composite structure of polycrystalline alumina pipes in an embodiment;

[0046] Figure 2 is a schematic diagram of a composite structure of polycrystalline alumina pipes in an embodiment;

[0047] Reference numerals:

[0048] 10 - polycrystalline alumina main pipe layer; 20 - transition layer; 30 - connection layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0049] In order to enable those skilled in the art to better understand the technical solutions in this application, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of this application.

[0050] Embodiment 1

[0051] The technical problem solved by this embodiment is that the defects of currently prepared polycrystalline alumina high-temperature lining tubes in use include: the service life needs to be improved. When subjected to the thermal cycling of the use environment, there is a phenomenon of surface cracking, especially at the position where it is connected to the outside, and crack propagation is likely to occur, resulting in a shortened life.

[0052] In order to improve the defects of the existing high-temperature lining tube preparation method and further enhance the function of the high-temperature lining tube, this embodiment provides a preparation method for a polycrystalline alumina tube composite structure, as Figure 1 shown, including the following steps:

[0053] S101: Sinter and form the polycrystalline alumina main tube layer 10 and roughen its outer surface to form a rough attachment surface;

[0054] S102: Prepare a transition layer 20 with a stepped tooth and stepped groove structure on the outside of the polycrystalline alumina main tube layer 10;

[0055] S103: Prepare a connection layer 30 on the transition layer 20 and mark the punching positions corresponding to the stepped grooves;

[0056] S104: Select punching positions according to the connection positions and process surface holes, and the surface holes penetrate into the stepped grooves;

[0057] S105: Install metal rivets on the selected surface holes.

[0058] In this method, a transition layer 20 is attached to the outside of the sintered and formed polycrystalline alumina main tube layer 10. The outer shape of the transition layer 20 includes a stepped tooth and stepped groove structure. A connection layer 30 is continuously prepared on the transition layer 20 and metal rivets are arranged on the surface holes of the connection layer 30. The positions of the surface holes correspond to those of the stepped grooves, and the metal rivets have a certain connection depth. Therefore, the thickness of the connection layer 30 needs to be set relatively thick. However, in this case, the stepped grooves can provide a depth space for installing the metal rivets, and the connection layer 30 as a whole can be set relatively thin without reducing the connection surface between the connection layer 30 and the transition layer 20. It has the advantages of mature and easy-to-implement preparation process, simple device structure, firm connection, stable setting of metal rivets, and light and thin overall device structure.

[0059] Embodiment 2

[0060] This embodiment provides a specific preparation method for a polycrystalline alumina tube composite structure, including the steps:

[0061] The preparation process of the main pipe layer includes: sintering and forming the polycrystalline alumina main pipe layer 10, roughening its outer surface to form a rough attachment surface; specifically, obtaining a blank and incorporating 0.5-2 wt% of nano-aluminum nitride, forming the main pipe blank of the doped blank by gel casting, sintering at 1700-1850 °C, and the heat preservation time is 2-5 hours. This step belongs to the adjustment of the conventional preparation method of polycrystalline alumina pipes, and the selected parameter range provides an optimized solution for the subsequent continuous preparation of the transition layer 20. In particular, the surface roughness of the polycrystalline alumina main pipe layer 10 is polished to 3-500 um by sandblasting.

[0062] The preparation process of the transition layer 20 includes: weaving alumina fibers or silicon carbide fibers into a shape, infiltrating with silica sol and then winding or attaching them to the outside of the polycrystalline alumina main pipe layer 10, forming axial stepped teeth and stepped grooves between the stepped teeth by laser etching or die pressing, the height of the stepped teeth is 50-200 mm, the tooth pitch is 200-800 mm, and sintering and post-treatment at 1500-1650 °C to fix the transition layer 20. It is preferably formed by die pressing, and the structure of the stepped teeth and stepped grooves is more regular, and it is convenient to prepare pipes with a half-step structure.

[0063] Specifically, the stepped teeth are serrated, trapezoidal or wavy, and 6-36 are evenly distributed along the outside of the polycrystalline alumina main pipe layer 10.

[0064] The preparation process of the connection layer 30 includes: pouring a mixed blank of alumina and mullite fibers outside the transition layer 20, and performing secondary sintering and forming at 1500-1600 °C. The connection stability of this material is better and the connection adhesion is better when synchronously receiving thermal and cold shocks with the transition layer 20.

[0065] Continuously, the polycrystalline alumina main pipe layer 10 including multiple coatings and the connection layer 30 is sectionally cut, and the punching positions are marked according to the screenshots at the cutting positions. Drill holes at the punching positions of the connection layer 30, the hole diameter is 0.1-5 mm, and internal threads are processed in the holes by ultrasonic vibration-assisted tapping to obtain surface holes, and the thread depth is 0.5-1 times the hole diameter.

[0066] The metal rivet includes a threaded connection part, a nut and a connecting rod, and the metal rivet is fixed in the surface hole through the threaded connection part. Optionally, it is fixed by diffusion welding, and the welding temperature is 800-1000 °C.

[0067] In order to enhance the self-cleaning function inside the pipeline, an aluminum oxynitride coating is deposited on the inner wall of the polycrystalline alumina main pipe layer 10 by plasma spraying, and the coating thickness is 100-2000 um.

[0068] In this method, a transition layer 20 is attached to the outer side of the sintered and formed polycrystalline alumina main pipe layer 10. The outer shape of the transition layer 20 includes a stepped tooth and a stepped groove structure. A connection layer 30 is further prepared on the transition layer 20, and a metal rivet is arranged on the surface hole of the connection layer 30. The position of the surface hole corresponds to that of the stepped groove. The metal rivet has a certain connection depth. Therefore, the thickness of the connection layer 30 needs to be set relatively thick. However, in this case, the stepped groove can provide a depth space for installing the metal rivet, and the connection layer 30 as a whole can be set relatively thin without reducing the connection surface between the connection layer 30 and the transition layer 20. It has the advantages of mature and easy-to-implement preparation process, simple device structure, firm connection, stable setting of metal rivets, and light and thin overall device structure.

[0069] Example 3

[0070] As Figure 2 shown, the multi-layer composite polycrystalline alumina high-temperature liner prepared by the above specific preparation method of the polycrystalline alumina pipe composite structure includes: a polycrystalline alumina main pipe layer 10, the cross-section of the polycrystalline alumina main pipe layer 10 is circular or elliptical; a transition layer 20, the transition layer 20 is arranged on the outer side of the polycrystalline alumina main pipe layer 10; a connection layer 30, the connection layer 30 is arranged on the outer side of the transition layer 20, and the connection layer 30 is provided with a surface hole at the connection position, and a metal rivet can be connected in the surface hole. The transition layer 20 is arranged on the outer side of the polycrystalline alumina main pipe layer 10. The function of the transition layer 20 is to wrap and connect the polycrystalline alumina main pipe layer 10 internally, perform functional modification and enhance the heat insulation performance of the polycrystalline alumina main pipe layer 10, and form an attachment surface externally, making the setting of the connection layer 30 more stable. The heat insulation performance of the transition layer 20 will also protect the connection layer 30. The connection layer 30 can be used to set surface holes and install metal rivets, so that the metal rivets are directly arranged on the multi-layer composite polycrystalline alumina high-temperature liner, simplifying the installation process and installation structure. While improving the stability of the connector, the metal rivet is connected to the connection layer 30 to avoid direct mechanical extrusion deformation of the polycrystalline alumina main pipe layer 10 by the metal rivet and cause cracks or crack propagation.

[0071] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification. The above embodiments only represent several implementation manners of the present application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application.

[0072] It should be noted that when an element is referred to as "fixed to" or "disposed on" another component, it can be directly on the other component or indirectly disposed on the other component; when a component is referred to as "connected to" another component, it can be directly connected to the other component or indirectly connected to the other component. It should be understood that the orientation or positional relationship indicated by terms such as "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation to the present application.

[0073] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, the meanings of "a plurality of" and "several" are two or more, unless otherwise specifically defined.

[0074] It should be noted that the structures, proportions, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the conditions under which the present application can be implemented. Therefore, they do not have a technical essence. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the efficacy that the present application can produce and the purpose that can be achieved, should still fall within the scope that the technical content disclosed in the present application can cover.

Claims

1. A method for preparing a composite structure of a polycrystalline alumina tube, characterized in that, It includes the following steps: Sinter and form a polycrystalline alumina main pipe layer, roughen its outer surface to form a rough attachment surface; Prepare a transition layer with stepped teeth and stepped groove structures on the outer side of the polycrystalline alumina main pipe layer; Prepare a connection layer on the transition layer and mark the drilling positions corresponding to the stepped grooves; Select the drilling positions according to the connection positions and process surface holes, and the surface holes penetrate into the stepped grooves; Install metal rivets on the selected surface holes.

2. The preparation method of the polycrystalline alumina tube composite structure according to claim 1, characterized in that, The step of sintering and forming the polycrystalline alumina main pipe layer includes: Obtain a blank and incorporate 0.5 - 2 wt% of nano-aluminum nitride. Gel-casting the doped blank to form a main pipe blank, and sintering at 1700 - 1850 °C for a holding time of 2 - 5 hours.

3. The preparation method of the polycrystalline alumina pipe composite structure according to claim 2, characterized in that, The step of roughening the surface of the polycrystalline alumina main pipe layer to form a rough attachment surface includes: Polish the surface roughness of the polycrystalline alumina main pipe layer to 3 - 500 um by sandblasting process.

4. The preparation method of the polycrystalline alumina tube composite structure according to claim 1, wherein The step of preparing a transition layer with stepped teeth and stepped groove structures on the outer side of the polycrystalline alumina main pipe layer includes: Weave alumina fibers or silicon carbide fibers into shape, infiltrate with silica sol, then wind or attach them to the outer side of the polycrystalline alumina main pipe layer, and form axial stepped teeth and stepped grooves between the stepped teeth by laser etching or die pressing. The height of the stepped teeth is 50 - 200 mm, the tooth pitch is 200 - 800 mm, and sinter and post-treat at 1500 - 1650 °C to fix the transition layer.

5. The preparation method of the polycrystalline alumina pipe composite structure according to claim 4, characterized in that, The stepped teeth are serrated, trapezoidal or wavy, and 6 - 36 of them are evenly distributed along the outer side of the polycrystalline alumina main pipe layer.

6. The preparation method of the polycrystalline alumina tube composite structure according to claim 1, characterized in that, The step of preparing a connection layer on the transition layer includes: Pour a mixed blank of alumina and mullite fibers on the outer side of the transition layer, and perform secondary sintering and forming at 1500 - 1600 °C.

7. The preparation method of the polycrystalline alumina pipe composite structure according to claim 6, characterized in that, The step of marking the drilling positions corresponding to the stepped grooves includes: Cut the cross-section of the polycrystalline alumina main pipe layer including the multi-layer coating and the connection layer, and mark the drilling positions according to the screenshot of the cutting position.

8. The preparation method of the polycrystalline alumina pipe composite structure according to claim 7, characterized in that The step of selecting the drilling positions according to the connection positions and processing surface holes includes: Drill holes at the drilling positions of the connection layer, with a hole diameter of 0.1 - 5 mm. Process internal threads in the drilled holes by ultrasonic vibration-assisted tapping to obtain surface holes, and the thread depth is 0.5 - 1 times the hole diameter.

9. The preparation method of the polycrystalline alumina tube composite structure according to claim 1, characterized in that, The step of installing metal rivets on the selected surface holes includes: The metal rivet includes a threaded connection part, a nut and a connecting rod. Fix the metal rivet in the surface hole through the threaded connection part and fix it by diffusion welding, and the welding temperature is 800 - 1000 °C.

10. The preparation method of the polycrystalline alumina tube composite structure according to claim 1, characterized in that Deposit an aluminum oxynitride coating on the inner wall of the polycrystalline alumina main pipe layer by plasma spraying, and the coating thickness is 100 - 2000 um.

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