Impact-resistant large ceramic impeller

Abstract

The utility model discloses an impact-resistant large ceramic impeller. The impact-resistant large ceramic impeller comprises a hub and an impeller body arranged on the hub, the impeller body is provided with a plurality of groups of outer lining plates on the radial outer side of the front cover plate or / and the rear cover plate of the impeller; the splicing position of every two adjacent sets of outer lining plates is arranged at the combination position of the blades and the front cover plate or the rear cover plate, and the two sides of each set of outer lining plates are arranged at the combination position of the blades and the front cover plate or the rear cover plate. A connecting part which is made of a silicon carbide material and is used for combining the outer lining plate into a whole is arranged between the blades and the inner side part of the front cover plate or / and the rear cover plate. The large ceramic impeller is better in structural performance and lower in production cost.

Description

Technical Field

[0001] The utility model belongs to the technical field of functional ceramic materials, and more specifically relates to an impact-resistant large-scale ceramic impeller. Background Art

[0002] The impeller of a slurry pump is the component most subject to wear and tear. It is typically made of wear-resistant alloy or rubber. However, in some severe wear conditions, wear-resistant alloy and rubber impellers often fail to meet service requirements. To improve impeller life, attempts are currently being made to utilize silicon carbide ceramic materials, which offer superior wear resistance. Common silicon carbide ceramics, depending on the process and raw materials, include pressureless sintered silicon carbide, hot-pressed silicon carbide, reaction-bonded silicon carbide, silicon nitride-bonded silicon carbide, and oxide-bonded silicon carbide. Pressureless sintered and hot-pressed silicon carbide, due to their complex molding and sintering processes, are currently only suitable for producing simple workpieces and are not suitable for complex, large parts like slurry pump impellers. Reaction-bonded silicon carbide, silicon nitride-bonded silicon carbide, and oxide-bonded silicon carbide, on the other hand, can be molded using casting or slipcasting techniques, allowing for the manufacture of complex workpieces. Currently, almost all silicon carbide ceramic impellers are manufactured from reaction-bonded silicon carbide, silicon nitride-bonded silicon carbide, and oxide-bonded silicon carbide.

[0003] Both silicon nitride-bonded silicon carbide and oxide-bonded silicon carbide can be cast, making them suitable for manufacturing complex workpieces such as impellers. The basic production process for both silicon nitride-bonded and oxide-bonded silicon carbide involves mixing α-SiC particles with metallic silicon powder, a binder, and water, pouring the mixture into a mold, and then releasing the mixture to dry. The blank is heated to 1420°C in high-purity nitrogen. The metallic silicon powder and nitrogen in the blank react to form silicon nitride, ultimately resulting in silicon nitride-bonded silicon carbide. The blank is then heated to 1420°C in oxygen or air. The metallic silicon powder and oxygen in the blank react to form silicon oxide, ultimately resulting in oxide-bonded silicon carbide. The porosity of silicon nitride-bonded silicon carbide is generally 8%-15%, and the α-SiC content is generally 65%-80%. Its flexural strength is generally 30-60 MPa. The porosity of oxide-bonded silicon carbide is generally 15%-20%, and the α-SiC content is generally 75%-85%. The flexural strength is generally 20-30Mpa.

[0004] Reaction-bonded silicon carbide ceramics generally refer to reaction-bonded silicon carbide. There is also reaction-formed silicon carbide, sometimes also called reaction-sintered silicon carbide, that is, the material is all β-SiC generated by carburization reaction, but this material has poor processability and high cost. There are currently no reports of its use in the manufacture of commercial applications of impellers. When manufacturing complex-shaped workpieces such as impellers, reaction-bonded silicon carbide is used, and slip casting is generally used. The manufacturing process is: raw materials containing α-SiC micropowder and carbon black micropowder are added with water, binders, dispersants, etc. and mixed evenly to form a slurry, which is then injected into the cavity of a gypsum mold (or other water-absorbing mold). The gypsum mold absorbs the water in the slurry. After the slurry loses some of its water content, the binder gives the blank a certain strength. The gypsum mold is removed to obtain the blank. After the ceramic blank is dried and trimmed, the blank and excess metal silicon particles are stacked in a reaction sintering furnace and sintered under vacuum or inert gas. The temperature is raised to about 800℃, and the binder and dispersant are completely carbonized. The temperature is continued to rise to 1500-1700℃, and the metallic silicon is liquefied or vaporized. It penetrates into the blank under the action of capillaries and reacts with the carbon in the blank to form β-SiC, and combines the α-SiC powder in the blank together. The excess metallic silicon fills the pores in the blank at the same time. After cooling, a ceramic material with very low porosity (generally less than 0.1%) is obtained, and the main components are silicon carbide (generally 85-93% of α-SiC + β-SiC) and free silicon (also called residual silicon, generally 7-15%).

[0005] In recent years, 3D printing technology has also been applied to the manufacture of reaction-sintered blanks. Reaction-sintered silicon carbide not only has much higher wear resistance than silicon nitride-bonded silicon carbide and oxide-bonded silicon carbide, but also has much higher mechanical strength than the latter two, with a typical bending strength of 250-500 MPa. Therefore, reaction-sintered silicon carbide is significantly superior to silicon nitride-bonded silicon carbide and oxide-bonded silicon carbide in terms of both wear resistance and strength. However, reaction-sintered silicon carbide technology also has a number of problems. Currently, reaction-sintered silicon carbide impellers manufactured using conventional technology can only achieve a diameter of approximately 500 mm. For example, the utility model patent with authorization announcement number CN209687784U discloses a "monolithic ceramic impeller," some models of which have been put into commercial use. However, the current market success is limited to a few small-scale reaction-sintered silicon carbide impellers with diameters generally not exceeding 500 mm. When manufacturing reaction-sintered silicon carbide impellers with larger diameters, it was found that the yield was very low, which led to a sharp increase in manufacturing costs. In addition, the manufactured reaction-sintered silicon carbide impellers had poor impact resistance. Not only were they prone to cracking under strong impact conditions, but the probability of cracking was also high under slight impact conditions.

[0006] Through in-depth research into the above phenomenon, we found that for ceramics such as silicon nitride-bonded silicon carbide, oxide-bonded silicon carbide, and sialon-bonded silicon carbide, due to their high porosity, these tiny pores can significantly reduce the internal stress generated during the ceramic sintering process and absorb the stress caused by external impact. As a result, the residual stress in the workpiece is low and the impact resistance is strong. However, due to the high porosity, their wear resistance and ability to withstand large particle erosion are significantly lower than low-porosity ceramic materials such as reaction-sintered silicon carbide.

[0007] Utility model patent application CN118407930A discloses a large silicon carbide ceramic impeller proposed by the applicant. The impeller is constructed by bonding together several components, including multiple ceramic impeller bodies. Because the ceramic bodies are significantly smaller than the impellers, the internal stress of the workpiece is significantly reduced, and the impeller's impact resistance is greatly improved. However, this technical solution suffers from the following major problems: both the slip-cast and 3D-printed workpieces experience significant shrinkage during the drying and sintering processes, resulting in low dimensional accuracy of the sintered impeller bodies. This makes it difficult to achieve the required precision during assembly. Machining to meet the required precision is costly, while machining without it can easily lead to significant misalignment at the joints, leaving a large seam during assembly, which can easily wear out the adhesive filling the seam. This not only reduces the lifespan and strength of the impeller but also reduces pump efficiency.

[0008] The utility model patent application, CN 219197703 U, discloses another ceramic impeller solution proposed by the applicant. The impeller comprises an impeller body made of silicon nitride-bonded silicon carbide (SiC). A liner made of reaction-sintered SiC is installed on the severely worn impeller flow channel surface. The liner and impeller body are integrally formed and sintered. This technical solution can improve the wear resistance of the impeller flow channel surface, but it also has some drawbacks. First, when the impeller is larger, the flow channel area is larger, and the number of liners must be increased to reduce the outer dimensions of the liners. Otherwise, during sintering, there is a high probability of liner detachment due to the difference in expansion coefficient between SiC-bonded SiC and reaction-sintered SiC. This results in a large number of joints on the impeller flow channel surface, resulting in a decrease in the hydraulic performance of the impeller. Second, many other areas of the impeller are also subject to severe wear, making it difficult to reliably install liners in these areas, shortening the impeller's life.

[0009] Another difficult problem to overcome when using larger impellers is the low strength of the blank. During the manufacturing process, cracks are prone to form in certain areas (particularly the front and rear covers), a problem that becomes more pronounced with larger impellers. When the impeller diameter exceeds 1000mm, the weight of the impeller blank often reaches over 1000kg. During the trimming, drying, and kiln loading processes, the blank needs to be hoisted and moved, making it difficult to support its own weight and prone to breakage. This results in a significant drop in yield and extremely high production costs. Summary of the Invention

[0010] In order to solve the deficiencies and shortcomings of the prior art, the purpose of the present invention is to provide a large-scale ceramic impeller that is impact-resistant.

[0011] The technical solution of the utility model to solve the above technical problems is:

[0012] A large, impact-resistant ceramic impeller comprises a hub and an impeller body arranged on the hub, wherein the impeller body is provided with several groups of outer lining plates at the radially outer sides of the front cover plate and / or the rear cover plate of the impeller; the joint between two adjacent groups of outer lining plates is provided at the junction of the blades and the front cover plate or the rear cover plate, and the two sides of each group of outer lining plates are provided at the junction of the blades and the front cover plate or the rear cover plate; a connecting portion made of silicon carbide material is provided between the blades and the inner side of the front cover plate and / or the rear cover plate for combining the outer lining plates into a whole.

[0013] Preferably, the impeller body is an integral sintered structure.

[0014] Preferably, the head and working surface of the blade are both provided with a blade liner, and the blade liner and the impeller body are an integral sintered structure.

[0015] Preferably, a front frame is provided on the front cover plate, and a front lining is provided on the axially outer side of the front frame; an outer lining provided on the front cover plate is provided with a groove for accommodating the front frame on its axial outer side, and the front frame, the impeller body and the front lining are bonded into a whole by an adhesive.

[0016] Preferably, a rear frame is provided on the rear cover plate, and a rear lining plate is provided on the axially outer side of the rear frame; an outer lining plate provided on the rear cover plate is provided with a groove for accommodating the rear frame on its axial outer side, and the rear frame, the impeller body and the rear lining plate are bonded into a whole by an adhesive.

[0017] Preferably, one or more outer anti-slip structures with narrow outer sides and wide inner sides are provided on the radial inner side of the outer lining plate, and an inner anti-slip structure adapted to the anti-slip structure is also provided on the connecting portion.

[0018] Preferably, an air gap filled with adhesive is provided between the outer anti-slip structure on the outer lining plate and the inner anti-slip structure on the connecting portion adapted thereto.

[0019] Preferably, an axial protrusion is provided on the outer lining plate, and a mounting hole that cooperates with the protrusion is provided on the front frame or the rear frame.

[0020] Preferably, the radial size of the outer lining plate is 0.1-0.2 times the diameter of the impeller body.

[0021] Preferably, a flow channel lining plate is provided on the surface of the flow channel on the radial inner side of the outer lining plate.

[0022] Preferably, a bonding silicon carbide layer is provided between the front skeleton and the outer lining plate, the bonding silicon carbide layer and the outer lining plate are sintered into one piece, and the average axial thickness of the bonding silicon carbide layer is less than 40% of the axial thickness of the outer lining plate; or a bonding silicon carbide layer is provided between the rear skeleton and the outer lining plate; the average axial thickness of the bonding silicon carbide layer between the rear skeleton and the outer lining plate is less than 40% of the axial thickness of the outer lining plate.

[0023] Preferably, after two adjacent sets of outer lining plates are spliced ​​together, a gap corresponding to the blade is formed at the splicing position, and the width S2 of the gap is smaller than the thickness S of the blade but larger than the width S3 of the gap at the outer edge of the gap.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] 1. The impeller body of the large ceramic impeller of the present invention is obtained by secondary molding and secondary sintering; that is, before the impeller body is formed, a primary molding is first performed to obtain a blank such as an outer lining plate, which is then sintered once to obtain a primary sintered part such as the outer lining plate; the primary sintered part is then placed in a molding mold for the impeller body and subjected to secondary molding, and the secondary molded impeller body blank is then subjected to secondary sintering to obtain the impeller body. When manufacturing large impellers with current technology, the strength of the blank after molding generally does not exceed 3MPa. Due to the large weight of the impeller, the blank is extremely susceptible to damage during trimming, drying, and kiln loading operations, especially the outer edge of the front cover plate or rear cover plate located between adjacent blades, which is easily broken and scrapped due to insufficient strength. After the secondary molding of the impeller body in the present invention, since the outer lining plate thereof has been sintered once, its bending strength is very high, generally reaching about 100 MPa. Since the joint between the outer lining plates is located at the joint between the blades and the front cover plate or the rear cover plate, the force applied to the outer lining plate is similar to that of a simply supported beam, with the fulcrums being the blades at both ends. The outer lining plate is similar to the steel bars in a reinforced concrete structure. This structure greatly improves the strength of the secondary molded blank, especially the outer edge of the front cover plate or the rear cover plate of the impeller body blank between the blades, thereby greatly reducing the breakage rate of the impeller body blank and reducing production costs.

[0026] 2. Because existing ceramic impellers suffer from severe radial wear along their outer edges, several outer lining plates are installed along the outer edges of the front and / or rear shrouds through the impeller body. The joint between two adjacent outer lining plates is located at the junction between the blades and the front or rear shrouds, reinforcing the impeller body with the outer lining plates, thereby enhancing the wear resistance of the impeller body. Furthermore, because the outer lining plates are significantly smaller than the overall dimensions of the impeller body, the internal stress in the outer lining plates after a single sintering process is significantly lower than that of a reaction-sintered impeller sintered entirely. The joint between the outer lining plates is located at the junction between the blades and the front and / or rear shrouds, distributing the greater internal stress generated by the secondary sintering process to the blade tails. While this increases the probability of cracks in the impeller body due to sintering stress at this joint, cracks there generally do not result in the impeller being scrapped, as the joint is well-stressed. Furthermore, the stress is largely relieved, thereby improving the impeller's impact resistance.

[0027] 3. The present invention effectively addresses the problem of insufficient precision and difficult-to-correct misalignment of multiple impeller bodies in the large silicon carbide ceramic impeller disclosed in application publication number CN118407930A. When the primary-sintered outer liner is positioned within the impeller body mold for secondary molding, even if the outer liner and mold do not completely fit, the secondary molding filling process corrects the misalignment caused by the splicing of the primary-sintered workpieces. This results in higher dimensional accuracy for the secondary-molded and secondary-sintered impeller body, thereby reducing subsequent processing and manufacturing costs while also improving the impeller's hydraulic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a cross-sectional view of a first specific embodiment of the impact-resistant large ceramic impeller of the present invention.

[0029] Figure 2 for Figure 1 Sectional view at AA.

[0030] Figure 3 A cross-sectional view of the impeller body.

[0031] Figure 4 for Figure 3 A cross-sectional view of the BB.

[0032] Figure 5 for Figure 3 Cross-sectional view of CC.

[0033] Figure 6 This is the main view of the outer lining.

[0034] Figure 7 for Figure 6 In the cross-sectional view of EE.

[0035] Figure 8 This is the main view of the outer lining after assembly.

[0036] Figure 9 for Figure 3 In the cross-sectional view of DD.

[0037] Figure 10 Schematic diagram of the secondary molding of the impeller body.

[0038] Figure 11 This is a cross-sectional view of the impeller body in the second specific embodiment of the impact-resistant large-scale ceramic impeller of the present invention.

[0039] Figure 12 for Figure 11 Cross-sectional view of FF.

[0040] Figure 13 This is the main view of the outer lining.

[0041] Figure 14 for Figure 13 Cross-sectional view of GG.

[0042] Figure 15 This is a cross-sectional view of a third specific embodiment of the impact-resistant large ceramic impeller of the present invention.

[0043] Figure 16 This is the main view of the outer lining.

[0044] Figure 17 for Figure 16 Sectional view of HH.

[0045] Figure 18 This is the main view of the rear skeleton.

[0046] In the figure: 1-outer lining, 2-connecting part, 3-rear skeleton, 4-front skeleton, 5-flow channel lining, 6-front lining, 7-rear lining, 8-hub, 9-blade skeleton, 10-adhesive, 11-blade lining, 12-blade cavity, 13-empty gap, 14-impeller body outer mold, 15-impeller body mud core, 16-impeller body pouring gate, 101-groove, 102-outer anti-slip structure, 103-axial protrusion, 104-bonded silicon carbide layer, 202-inner anti-slip structure, 303-mounting hole. DETAILED DESCRIPTION

[0047] The present invention will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto. Example

[0048] like Figures 1-9 As shown, the diameter of the large impact-resistant ceramic impeller of the present invention is 1430 mm, and it includes a hub 8 and an impeller body arranged on the hub 8, wherein the impeller body is provided with 5 outer lining plates 1 on the radial outer sides of the front cover plate and the rear cover plate of the impeller; the joint between two adjacent groups of outer lining plates 1 is provided at the junction of the blade and the front cover plate or the rear cover plate, and the two sides of each group of outer lining plates 1 are provided at the junction of the blade and the front cover plate or the rear cover plate; a connecting portion 2 made of silicon carbide material is provided between the blade and the inner side of the front cover plate or / and the rear cover plate for combining the outer lining plates 1 into a whole.

[0049] like Figure 3As shown, the impeller body is a monolithic sintered structure, allowing the joints between the outer liner plates 1 to be filled with bonded silicon carbide. Bonded silicon carbide refers to materials with a silicon carbide content exceeding 60%, formed by sintering at temperatures above 1000°C, such as silicon nitride-bonded silicon carbide, oxide-bonded silicon carbide, sialon-bonded silicon carbide, and reaction-bonded silicon carbide. Because bonded silicon carbide has greater wear resistance than adhesives, the impeller body is protected from premature damage to the ceramic impeller due to wear at the joints.

[0050] like Figure 2 、 Figure 4 As shown, blade liners 11 are provided on the head and working surface of the blade, and the blade liners 11 and the impeller body are an integral sintered structure; since the head and working surface of the blade are the parts with more severe wear, providing blade liners 11 at these parts can significantly improve the life of the impeller.

[0051] like Figure 2 、 Figure 3 、 Figure 6 、 Figure 7 、 Figure 8 As shown, the front cover plate is provided with a front frame 4, which can significantly improve the impact resistance of the front cover plate. A front liner plate 6 is provided on the axial outer side of the front frame 4. The outer liner plate 1 provided on the front cover plate is provided with a groove 101 on its axial outer side for accommodating the front frame 4. The front frame 4, the impeller body, and the front liner plate 6 are bonded together into a whole by an adhesive. By providing the outer liner plate 1 provided with the groove 101 in the axial direction for accommodating the front frame 4 on the front cover plate, the front frame 4, the impeller body, and the front liner plate 6 are bonded together into a whole by an adhesive, so that the outer liner plate 1 is bonded to the front frame 4, preventing the outer liner plate 1 from falling out of the impeller body.

[0052] like Figure 1 、 Figure 3 As shown, the rear cover plate is provided with a rear frame 3, which can significantly improve the impact resistance of the rear cover plate, and a rear lining plate 7 is provided on the axial outer side of the rear frame 3; the outer lining plate 1 provided on the rear cover plate is provided with a groove 101 for accommodating the rear frame 3 on its axial outer side, and the rear frame 3, the impeller body and the rear lining plate 7 are bonded into a whole by an adhesive; in this way, the outer lining plate 1 can be bonded to the rear frame 3 to prevent the outer lining plate 1 from falling off from the impeller body.

[0053] like Figure 6As described above, the radial dimension S1 of the outer lining plate 1 is 168 mm, and the diameter of the impeller body is 1430 mm, that is, the radial dimension S1 of the outer lining plate 1 is 0.117 times the diameter of the impeller. This makes the outer lining plate 1, when subjected to stress, break in the direction of the cross-section with smaller bending strength of the workpiece, that is, pointing to the axial direction of the impeller body. Therefore, even if the outer lining plate 1 is broken by impact, since both ends of the break are bonded to the front frame 4 / rear frame 3 and the front lining plate 6 / rear lining plate 7 as a whole, the probability of falling off from the impeller body is very low, and the reliability of the impeller is improved.

[0054] like Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 As shown, a flow channel lining plate 5 is provided on the radially inner flow channel surface of the outer lining plate 1 to improve the wear resistance of the impeller; in this embodiment, two flow channel lining plates 5 are provided on each flow channel surface, so a total of 10 flow channel lining plates 5 are provided.

[0055] like Figure 2 and Figure 4 As shown, a blade lining 11 is provided on the head and working surface of the blade. On each blade, the connecting portion 2 connects the front cover plate and the rear cover plate into one body; a blade cavity 12 for accommodating the blade skeleton 9 and the adhesive 10 is provided on the connecting portion 2 of the blade.

[0056] In this embodiment, the material of the outer lining plate 1 and the flow channel lining plate 5 is reaction-sintered silicon carbide, and the material of the connecting part 2 is silicon nitride bonded silicon carbide; and the material of the front frame 4, the rear frame 3, the blade frame 9 and the hub 8 is carbon steel, among which the rear frame 3, the blade frame 9 and the hub 8 are welded into a whole.

[0057] See also Figures 1-9 The specific manufacturing process of the impeller body of this embodiment is:

[0058] (1) Injecting grout into a gypsum mold to form the blanks of the outer lining plate 1, the blade lining plate 11 and the flow channel lining plate 5;

[0059] (2) After trimming and drying the blanks of the outer lining plate 1, the blade lining plate 11 and the flow channel lining plate 5, the blanks are placed in a vacuum sintering furnace, metallic silicon is stacked in proportion outside the blanks, and the blanks are heated to 1500-1700°C under vacuum conditions for a single sintering to obtain the outer lining plate 1, the blade lining plate 11 and the flow channel lining plate 5 of reaction sintered material;

[0060] (3) Position the outer lining plate 1, blade lining plate 11, etc. on the corresponding positions of the impeller body outer mold 14 and the impeller body mud core 15, and fill the mold cavity with a mixture of silicon nitride and silicon carbide from the impeller body pouring port 16 for secondary molding. After demolding, the impeller body blank (such as Figure 10 shown);

[0061] (4) After the impeller body blank is dried, it is placed in a nitriding furnace, and high-purity nitrogen is introduced for secondary sintering, and heated to about 1400°C to obtain the impeller body;

[0062] The impeller body manufactured according to the above process has a gap between the outer lining plate 1 and the secondary molding mold during the secondary molding process, and a layer of silicon nitride combined with silicon carbide layer mixture will be formed on the surface of part of the outer lining plate 1, and after sintering, it will become a silicon nitride combined with silicon carbide layer (i.e. Figure 7 When the impeller is bonded, the adhesive with lower viscosity can penetrate the pores of the silicon nitride bonded silicon carbide layer to bond the outer lining plate 1 and the front frame 4 / rear frame 3 into a whole. In order to improve the bonding force to the outer lining plate 1, the average axial thickness of the silicon nitride bonded silicon carbide layer is less than 40% of the axial thickness of the outer lining plate 1.

[0063] In this embodiment, the axial thickness of the outer lining plate 1 is 62 mm, the axial thickness of the silicon nitride bonded silicon carbide layer between the front skeleton 4 and the outer lining plate 1 is 2 mm, and the thickness of the silicon nitride bonded silicon carbide layer between the rear skeleton 3 and the outer lining plate 1 is 1 mm.

[0064] like Figure 5 、 Figure 8 As shown, when the five outer lining plates 1 are assembled, a gap 13 corresponding to the blade is formed at the joint. The width S2 of the gap 13 is less than the thickness S of the blade but greater than the width S3 of the gap at the outer edge of the gap 13. This structure can use the silicon nitride-bonded silicon carbide material filled in the relatively large gap in the gap 13 as a binder to improve the strength of the impeller blank and the impeller body, while ensuring that there is a smaller gap at the outer edge of the impeller body between the outer lining plates 1, so that the silicon nitride-bonded silicon carbide filled therein is not easily worn, thereby improving the wear resistance of the impeller body. The pores in the silicon nitride-bonded silicon carbide material in the gap 13 can release the stress generated by the secondary sintering, thereby reducing the probability of impeller rupture and improving the impact resistance of the impeller. At the same time, the silicon nitride-bonded silicon carbide in this area is also protected by the blade lining 11 to prevent it from rapid wear. In this embodiment, the thickness S of the blade at the corresponding position is 70 mm, the gap S2 of the empty gap 13 is 30-40 mm, and the gap S3 at the outer edge of the empty gap 13 is 0.5-2 mm.

[0065] In this embodiment, the material of the front lining plate 6 and the rear lining plate 7 is pressureless sintered silicon carbide, and the adhesive is acrylic resin. Example

[0066] This embodiment is substantially the same as embodiment 1, with the following main differences:

[0067] like Figure 11 、 Figure 12 、 Figure 13 、 Figure 14 As shown, the diameter of the impeller in this embodiment is 1620 mm, and five outer lining plates 1 are provided on the front cover of the impeller body, and five outer lining plates 1 are also provided on the rear cover. Two outer anti-slip structures 102 with narrow outer sides and wide inner sides are provided on the radial inner side of each outer lining plate 1, as shown in FIG. Figure 12 、 13 In the figure, the inner width B1 of the outer anti-slip structure is 55 mm, and the outer width B2 is 52 mm. The inner anti-slip structure 202 adapted to the outer anti-slip structure 102 is naturally formed on the connecting portion 2 during the secondary molding; the radial dimension S4 of the outer lining plate 1 is 162 mm, that is, the radial dimension of the outer lining plate 11 is 0.1 times the impeller diameter.

[0068] By arranging one or more outer anti-slip structures with narrow outer sides and wide inner sides on the radial inner side of the outer lining plate 1, an inner anti-slip structure 202 adapted to the outer anti-slip structure 102 will naturally be formed on the connecting portion 2 during casting, thereby preventing the outer lining plate 1 from falling out of the impeller body under the action of centrifugal force.

[0069] In this embodiment, the outer lining plate 1 is made of pressureless sintered silicon carbide, and the connecting portion 2 is made of oxide-bonded silicon carbide.

[0070] The manufacturing process of the impeller body of this embodiment is substantially the same as that of embodiment 1, with the main differences being:

[0071] After primary sintering and before secondary molding, a 0.1-0.5mm thick layer of organic glue is applied to the outer anti-slip structure 102 and other surfaces of the outer liner 1. During secondary sintering after secondary molding, the organic glue is burned away. After secondary sintering, an air gap is left between the outer anti-slip structure 102 and the inner anti-slip structure 202, preventing cracking or significant residual stress caused by differences in expansion coefficients. During the subsequent bonding process, adhesive is infiltrated into this air gap, improving the impeller's strength and impact resistance. Example

[0072] like Figure 15-18 As shown, this embodiment is substantially the same as embodiment 1, with the following main differences:

[0073] The impeller has a diameter of 950 mm, the outer lining plate 1 is made of pressureless sintered silicon carbide or reaction-sintered silicon carbide, and the connecting portion 2 is made of reaction-sintered silicon carbide.

[0074] Each outer lining plate 1 has two axial protrusions 103 and is embedded in the corresponding mounting holes 303 on the front frame 4 / rear frame 3. This can improve the bonding force between the outer lining plate 1 and the front frame 4 / rear frame 3 and prevent the outer lining plate 1 from falling off the impeller body.

[0075] Because the distribution of internal stress and the direction of impact cracking in the outer liner 1 after primary and secondary sintering are related to its shape, a larger radial dimension allows it to cover a wider area, improving the impeller's wear resistance. However, the stress distribution of this shape causes the direction of the cracking to have a smaller angle with the tangent of the outer circle after impact, making the fractured parts more likely to fall off, thus causing the impeller to fail and reduce its reliability. Conversely, when the radial dimension of the outer liner 1 is smaller, the stress distribution causes the direction of the cracking to have a larger angle with the tangent of the outer circle, meaning that the crack extends toward the center of the circle. After the outer liner 1 breaks, the stress is released, and the crack no longer extends toward the connecting portion 2 at the center of the circle. Since the broken outer liner 1 can still be fixed to the front frame 4 or the rear frame 3 with adhesive, the impeller can continue to be used, thus improving the impeller's reliability. However, if the area covered by the outer liner 1 is too small, the overall wear resistance of the impeller will be reduced, or the installation of the flow channel liner 5 will be more difficult. When the radial dimension of the outer lining plate 1 is 0.1-0.2 times the diameter of the impeller, the above contradiction can be balanced.

[0076] Therefore, after the impeller body of this embodiment is bonded with the adhesive, the outer lining plate 1 can be prevented from falling off after cracks appear on the outer lining plate 1. The radial dimension S5 of the outer lining plate 1 is 130 mm, which is 0.126 times the impeller diameter.

[0077] The above is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited to the above content. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A large impact-resistant ceramic impeller, characterized in that: It includes a hub and an impeller body arranged on the hub, wherein the impeller body is provided with several groups of outer lining plates at the radial outer side of the front cover plate or / and the rear cover plate of the impeller; the joint between two adjacent groups of outer lining plates is arranged at the junction of the blade and the front cover plate or the rear cover plate, and the two sides of each group of outer lining plates are arranged at the junction of the blade and the front cover plate or the rear cover plate; a connecting part made of silicon carbide material is provided between the blade and the inner side of the front cover plate or / and the rear cover plate for combining the outer lining plates into a whole.

2. The impact-resistant large ceramic impeller according to claim 1, characterized in that: The impeller body is an integral sintered structure.

3. The impact-resistant large ceramic impeller according to claim 1, characterized in that: The head and working surface of the blade are both provided with a blade liner, and the blade liner and the impeller body are an integral sintered structure.

4. The impact-resistant large ceramic impeller according to claim 1, characterized in that: A front frame is provided on the front cover plate, and a front lining plate is provided on the axial outer side of the front frame; an outer lining plate provided on the front cover plate is provided with a groove for accommodating the front frame on its axial outer side, and the front frame, the impeller body and the front lining plate are bonded into a whole by an adhesive.

5. The impact-resistant large ceramic impeller according to claim 4, characterized in that: A rear frame is provided on the rear cover plate, and a rear lining plate is provided on the axial outer side of the rear frame; an outer lining plate provided on the rear cover plate is provided with a groove for accommodating the rear frame on its axial outer side, and the rear frame, the impeller body and the rear lining plate are bonded into a whole by an adhesive.

6. The impact-resistant large ceramic impeller according to claim 1, characterized in that: One or more outer anti-slip structures with narrow outer sides and wide inner sides are provided on the radial inner side of the outer lining plate, and an inner anti-slip structure adapted to the anti-slip structure is also provided on the connecting portion.

7. The impact-resistant large ceramic impeller according to claim 6, characterized in that: An air gap filled with adhesive is provided between the outer anti-slip structure on the outer lining plate and the inner anti-slip structure on the connecting portion adapted thereto.

8. The impact-resistant large ceramic impeller according to claim 5, characterized in that: The outer lining plate is provided with an axial protrusion, and the front frame or the rear frame is provided with a mounting hole that matches the protrusion.

9. The impact-resistant large ceramic impeller according to claim 1, characterized in that: The radial dimension of the outer lining plate is 0.1-0.2 times the diameter of the impeller body.

10. The impact-resistant large ceramic impeller according to claim 5, characterized in that: A bonding silicon carbide layer is provided between the front skeleton and the outer lining plate, the bonding silicon carbide layer and the outer lining plate are sintered into one body, and the average axial thickness of the bonding silicon carbide layer is less than 40% of the axial thickness of the outer lining plate; or a bonding silicon carbide layer is provided between the rear skeleton and the outer lining plate; the average axial thickness of the bonding silicon carbide layer between the rear skeleton and the outer lining plate is less than 40% of the axial thickness of the outer lining plate.

11. The impact-resistant large ceramic impeller according to claim 1, characterized in that: After two adjacent sets of outer lining plates are joined together, a gap corresponding to the blade is formed at the joint. The width S2 of the gap is smaller than the thickness S of the blade but larger than the width S3 of the gap at the outer edge of the gap.

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