Cavitation-resistant lining material and preparation method thereof

Abstract

The invention discloses a cavitation-resistant lining material and a preparation method thereof.The material comprises a metal base layer, a copper powder layer sintered on one face of the metal base layer and a plastic layer embedded into and covering the copper powder layer, and the plastic layer is prepared from, by weight, 3-10 parts of molybdenum disulfide, 1-3 parts of iron oxide red, 5-10 parts of PFA, 3-10 parts of crystalline aluminum hydroxide and 67-88 parts of PTFE emulsion. According to the invention, alpha-type crystalline aluminum hydroxide, PFA and PTFE are introduced to achieve a synergistic effect, and a multi-layer composite structure and a specific sintering process are adopted, so that the cavitation resistance, interface bonding strength and comprehensive mechanical properties of the bushing material are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, specifically to a cavitation-resistant bushing material and its preparation method. Background Technology

[0002] PTFE materials are widely used in bushing components in hydraulic systems, pumps, valves, and marine propulsion systems due to their excellent corrosion resistance, low coefficient of friction, and good self-lubricating properties. However, pure PTFE materials suffer from low hardness, poor load-bearing capacity, and susceptibility to cavitation wear, which limits their service life under high-speed and high-pressure conditions.

[0003] Existing technologies often improve the mechanical properties of PTFE by adding fillers such as bronze powder, glass fiber, and carbon fiber. However, these fillers have weak interfacial bonding with the PTFE matrix and are prone to detachment under long-term cavitation impact, leading to material failure. Silane coupling agents are also used to treat the PTFE matrix, making the bonding tighter. However, for industrial production, this adds an extra step, increasing costs and causing problems. Furthermore, ordinary fillers have limited effectiveness in suppressing cavitation damage, making it difficult to meet the application requirements of high-reliability bushings. Summary of the Invention

[0004] In view of this, the present invention provides a cavitation-resistant bushing material and its preparation method. By introducing crystalline aluminum hydroxide and PFA and PTFE synergistic effects, and by adopting a multi-layer composite structure and a specific sintering process, the cavitation resistance, interfacial bonding strength and comprehensive mechanical properties of the bushing material are significantly improved.

[0005] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention discloses a cavitation-resistant bushing material, comprising a metal base layer, a copper powder layer sintered on one side of the metal base layer, and a plastic layer embedded in and covering the copper powder layer, wherein the plastic layer is prepared from the following components in parts by weight: 3-10 parts of molybdenum disulfide, 1-3 parts of iron oxide red, 5-10 parts of PFA, 3-10 parts of crystalline aluminum hydroxide, and 67-88 parts of PTFE emulsion.

[0006] As a further aspect of the present invention: the crystalline aluminum hydroxide is α-Al(OH)3.

[0007] As a further aspect of the present invention, the metal base layer is made of low-carbon steel.

[0008] Secondly, this invention discloses a method for preparing the cavitation-resistant bushing material as described above, comprising the following steps: (1) CuSn8Zn3 spherical copper powder is evenly spread on a metal substrate. After sintering, a porous copper powder layer is formed on the metal substrate to obtain a copper powder plate. (2) Weigh molybdenum disulfide, iron oxide red, PFA (perfluoroalkoxy resin), and aluminum hydroxide according to the weight parts, mix them thoroughly to obtain a mixed dry powder; add the mixed dry powder to PTFE emulsion and continue stirring, then add alcohol to finely break the emulsion to form moist plastic particles; (3) The wet plastic particles are crushed and evenly sprinkled on the copper powder plate, and then the composite plate is obtained by rolling. (4) The composite board is dried, and then rolled a second time after drying; (5) The plate obtained in step (4) is sintered in a protective atmosphere and then rolled three times to obtain the cavitation resistant bushing material.

[0009] As a further aspect of the present invention: in step (1), the sintering temperature is 890-910℃ and the sintering time is 40-60min.

[0010] As a further aspect of the present invention: in step (4), the drying temperature is 240-260℃ and the drying time is 4-8min.

[0011] As a further aspect of the present invention: in step (5), the sintering temperature is 360-380℃ and the sintering time is 10-30min.

[0012] As a further aspect of the present invention: in step (4), the thickness of the plate after secondary rolling is 60-80 μm smaller than that of the dried plate.

[0013] As a further aspect of the present invention: in step (1), the porosity of the copper powder layer is 15%-30%. If the porosity is too high, the final material will not be able to bear the load. If the porosity is too low, the metal layer and the plastic layer will not bond well.

[0014] The advantages of introducing crystalline Al(OH)3 in this invention are twofold. First, its molecular surface is rich in hydroxyl groups (-OH). These polar hydroxyl groups can form hydrogen bonds or van der Waals forces with the small number of unstable end groups (such as carboxyl groups -COOH) that may be generated during the processing of PTFE due to slight shearing or thermal effects. Although PTFE itself is inert, this difference in surface polarity makes the interfacial compatibility and wettability between aluminum hydroxide and the PTFE matrix better, and the interfacial bonding force stronger, making it superior to alumina in terms of interfacial adhesion and compatibility. Second, compared with amorphous Al(OH)3, crystalline Al(OH)3 has higher hardness, stability, and is less prone to decomposition, and has stronger resistance to cavitation.

[0015] Both PFA and PTFE are perfluoropolymers with good thermodynamic compatibility. Through melt co-sintering, they achieve molecular-level fusion, conforming to the principle of "like dissolves like." Furthermore, during the dry powder stage, high-speed shear mixing ensures all fillers come into contact with PFA. Because PFA has a higher surface energy than PTFE, it binds more easily with other fillers, acting as a "binder" between PTFE and other fillers. This better promotes the bonding of difficult-to-bond fillers to the matrix, improving the material's resistance to cavitation. In addition, PFA has an extremely low coefficient of friction, only slightly higher than PTFE, but its wear resistance, creep resistance, tensile strength, toughness, and hardness are significantly superior to PTFE.

[0016] Compared with the prior art, the beneficial effects of the present invention are: The cavitation-resistant bushing material prepared by this invention utilizes the polar groups on the surface of α-type crystalline aluminum hydroxide to form a strong interfacial bond with the unstable end groups of PTFE, and uses PFA as a molecular bridge and a highly efficient adhesive to firmly fuse the PTFE matrix with various fillers, thereby greatly solving the problem of cavitation failure caused by filler detachment in traditional PTFE composite materials.

[0017] In terms of macroscopic properties, this material exhibits excellent resistance to cavitation wear, while also possessing a low coefficient of friction, high wear resistance, excellent creep resistance, and higher tensile strength and toughness. This comprehensive improvement in performance enables it to adapt well to harsh operating conditions involving high speed and high pressure.

[0018] Furthermore, the preparation method provided by this invention optimizes key process steps such as dry powder mixing, alcohol demulsification, multi-stage rolling, and protective atmosphere sintering. While ensuring material performance, it achieves stable and controllable process flow, avoids complex treatments such as the use of coupling agents, and has good prospects for industrial application. Attached Figure Description

[0019] Figure 1 The surface damage morphology of the final product obtained in Comparative Example 1 after a 30-minute standard cavitation test is shown. Figure 2 The surface damage morphology of the final product obtained in Comparative Example 2 after a 30-minute standard cavitation test; Figure 3 The surface damage morphology of the final product obtained in Comparative Example 3 after a 30-minute standard cavitation test; Figure 4 The surface damage morphology of the final product obtained in Example 1 after a 30-minute standard cavitation test; Figure 5 The surface damage morphology of the final product obtained in Example 2 after a 30-minute standard cavitation test; Figure 6The surface damage morphology of the final product obtained in Example 3 after a 30-minute standard cavitation test; Figure 7 The surface damage morphology of the final product obtained in Comparative Example 4 after a 30-minute standard cavitation test is shown. Detailed Implementation

[0020] To facilitate understanding of the present invention, a more comprehensive description will be given below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0022] Example 1 (1) CuSn8Zn3 spherical copper powder is evenly spread on SPCC low carbon steel plate and sintered to form a copper powder layer with pores, and a copper powder plate is obtained; wherein, the sintering temperature is 900℃ and the sintering time is 50min; (2) Weigh out 8 parts of molybdenum disulfide, 2 parts of iron oxide red, 10 parts of PFA, and 6 parts of α-aluminum hydroxide (Zibo Pengfeng New Materials, pf-1) according to the weight proportions, and stir using a high-speed shear machine. Stop stirring for 20 seconds every 8 seconds to allow cooling, to prevent agglomeration of micro and nano powders, repeating this process 5 times. Then weigh out 74 parts of PTFE emulsion (60% solid content), stir using a mixer, and add the evenly mixed dry powder during the stirring process. After stirring for 10 minutes, add 30 parts of alcohol to break the emulsion, forming moist plastic particles. Place the plastic particles into a crusher for crushing.

[0023] (3) Sprinkle crushed plastic particles onto the copper powder plate and laminate it using a rolling mill with adjusted dimensions. The thickness of the plastic layer on the composite plate is controlled between 0.01-0.03 mm; (4) The composite plate is dried in a mesh belt furnace with the temperature and time set at 250℃ for 6 minutes. After completion, it is rolled by a rolling mill with the dimensions adjusted so that the thickness of the rolled plate is 70μm smaller than that of the dried plate; (5) Continue to sinter the plate in a nitrogen-filled box furnace at a temperature of 370°C for 20 minutes. After completion, continue to roll the plate through a mill with adjusted dimensions to obtain a finished product with a thickness of 1.98 mm.

[0024] Example 2 (1) CuSn8Zn3 spherical copper powder is evenly spread on SPCC low carbon steel plate and sintered to form a copper powder layer with pores, and a copper powder plate is obtained; wherein, the sintering temperature is 890℃ and the sintering time is 60min; (2) Weigh out 10 parts of dry molybdenum disulfide powder, 3 parts of iron oxide red, 5 parts of PFA, and 3 parts of α-aluminum hydroxide (Zibo Pengfeng New Materials, pf-1) according to the weight proportions, and stir using a high-speed shearing machine. During the stirring process, stop for 10 seconds every 6 seconds to allow cooling to prevent the micro powder and nano powder from agglomerating, and repeat this process 7 times. Then weigh out 79 parts of PTFE emulsion (solid content of 60%), stir using a mixer, add the evenly mixed dry powder during the stirring process, and continue stirring for 5 minutes. Weigh out 20 parts of alcohol to demulsify and form moist plastic particles, and put the plastic particles into a crusher for crushing.

[0025] (3) Sprinkle crushed plastic particles on the copper powder plate and perform composite by rolling mill with adjusted size. The thickness of the plastic layer on the composite plate is controlled at 0.01-0.03mm. (4) The composite plate is dried in a mesh belt furnace with the temperature and time set at 240℃ for 8 minutes. After completion, it is rolled through a rolling mill with the dimensions adjusted, and the thickness of the rolled plate is 60μm smaller than that of the dried plate. (5) Continue to put the plate into a nitrogen-filled box furnace for sintering at a temperature of 360°C for 30 minutes. After completion, continue to roll the plate through a mill with adjusted dimensions to obtain a finished product with a thickness of 1.98 mm.

[0026] Example 3 (1) CuSn8Zn3 spherical copper powder is evenly spread on SPCC low carbon steel plate and sintered to form a copper powder layer with pores, and a copper powder plate is obtained; wherein, the sintering temperature is 910℃ and the sintering time is 40min; (2) Weigh out 3 parts of molybdenum disulfide, 1 part of iron oxide red, 10 parts of PFA, and 10 parts of α-aluminum hydroxide (Zibo Pengfeng New Materials, pf-1) according to the weight proportions. Stir using a high-speed shearing machine. Stop stirring for 30 seconds every 10 seconds to allow cooling to prevent agglomeration of micro powder and nano powder. Repeat this process 3 times. Weigh out 76 parts of PTFE emulsion (60% solid content) and stir using a mixer. Add the evenly mixed dry powder during the stirring process. After stirring for 15 minutes, weigh out 40 parts of alcohol to demulsify and form moist plastic particles. Put the plastic particles into a crusher for crushing.

[0027] (3) Sprinkle crushed plastic particles on the copper powder plate and perform composite by rolling mill with adjusted size. The thickness of the plastic layer on the composite plate is controlled at 0.01-0.03mm. (4) The composite plate is dried in a mesh belt furnace with the temperature and time set at 260℃ for 4 minutes. After completion, it is further dried by rolling mill with the dimensions adjusted, and the thickness of the rolled plate is 80μm smaller than that of the dried plate. (5) Continue to put the plate into a box furnace with nitrogen gas for sintering at a temperature of 380°C for 10 minutes. After completion, continue to roll the plate through a rolling mill with adjusted dimensions to obtain a finished product with a thickness of 1.98 mm.

[0028] Comparative Example 1 (1) CuSn8Zn3 spherical copper powder is evenly spread on SPCC low carbon steel plate and sintered to form a copper powder layer with pores, and a copper powder plate is obtained; wherein, the sintering temperature is 900℃ and the sintering time is 50min; (2) Weigh 8 parts of molybdenum disulfide and 2 parts of iron oxide according to the weight proportions. Stir using a high-speed shearing machine. Stop stirring for 20 seconds every 8 seconds to allow cooling and prevent agglomeration of micro powder and nano powder. Repeat this process 5 times. Weigh 90 parts of PTFE emulsion (60% solid content) and stir using a mixer. Add the evenly mixed dry powder during the stirring process. After stirring for 10 minutes, weigh 30 parts of alcohol to break the emulsion and form moist plastic particles. Put the plastic particles into a crusher for crushing.

[0029] (3) Sprinkle crushed plastic particles on the copper powder plate and perform composite by rolling mill with adjusted size. The thickness of the plastic layer on the composite plate is controlled at 0.01-0.03mm. (4) The composite plate is dried in a mesh belt furnace with the temperature and time set at 250°C for 6 minutes. After completion, it is rolled through a rolling mill with the dimensions adjusted, and the thickness of the rolled plate is 70 μm smaller than that of the dried plate. (5) Continue to put the plate into a nitrogen-filled box furnace for sintering at a temperature of 370°C for 20 minutes. After completion, continue to roll it to the finished size through a rolling mill with the dimensions adjusted.

[0030] Comparative Example 2 (1) CuSn8Zn3 spherical copper powder is evenly spread on SPCC low carbon steel plate and sintered to form a copper powder layer with pores, and a copper powder plate is obtained; wherein, the sintering temperature is 900℃ and the sintering time is 50min; (2) Weigh out 8 parts of molybdenum disulfide, 2 parts of iron oxide red, and 10 parts of PFA according to the weight proportions. Stir using a high-speed shear mixer. Stop stirring for 20 seconds every 8 seconds to allow cooling and prevent agglomeration of micro powder and nano powder. Repeat this process 5 times. Weigh out 80 parts of PTFE emulsion (solid content 60%) and stir using a mixer. Add the evenly mixed dry powder during the stirring process. After stirring for 10 minutes, weigh out 30 parts of alcohol to break the emulsion and form moist plastic particles. Put the plastic particles into a crusher for crushing.

[0031] (3) Sprinkle crushed plastic particles on the copper powder plate and perform composite by rolling mill with adjusted size. The thickness of the plastic layer on the composite plate is controlled at 0.01-0.03mm. (4) The composite plate is dried in a mesh belt furnace with the temperature and time set at 250°C for 6 minutes. After completion, it is rolled through a rolling mill with the dimensions adjusted, and the thickness of the rolled plate is 70 μm smaller than that of the dried plate. (5) Continue to put the plate into a nitrogen-filled box furnace for sintering at a temperature of 370°C for 20 minutes. After completion, continue to roll it to the finished size through a rolling mill with the dimensions adjusted.

[0032] Comparative Example 3 (1) CuSn8Zn3 spherical copper powder is evenly spread on SPCC low carbon steel plate and sintered to form a copper powder layer with pores, and a copper powder plate is obtained. The sintering temperature is 900℃ and the sintering time is 50min. (2) Weigh out 8 parts of molybdenum disulfide, 2 parts of iron oxide red, and 6 parts of α-aluminum hydroxide (Zibo Pengfeng New Materials, pf-1) according to the weight proportions. Stir using a high-speed shear machine. Stop stirring for 20 seconds every 8 seconds to allow cooling and prevent agglomeration of micro powder and nano powder. Repeat this process 5 times. Weigh out 84 parts of PTFE emulsion (60% solid content) and stir using a mixer. Add the evenly mixed dry powder during the stirring process. After stirring for 10 minutes, weigh out 30 parts of alcohol to break the emulsion and form moist plastic particles. Put the plastic particles into a crusher for crushing.

[0033] (3) Sprinkle crushed plastic particles on the copper powder plate and perform composite by rolling mill with adjusted size. The thickness of the plastic layer on the composite plate is controlled at 0.01-0.03mm. (4) The composite plate is dried in a mesh belt furnace with the temperature and time set at 250°C for 6 minutes. After completion, it is rolled through a rolling mill with the dimensions adjusted, and the thickness of the rolled plate is 70 μm smaller than that of the dried plate. (5) Continue to put the plate into a nitrogen-filled box furnace for sintering at a temperature of 370°C for 20 minutes. After completion, continue to roll it to the finished size through a rolling mill with the dimensions adjusted.

[0034] Comparative Example 4 Compared with Example 1, the only difference is that α-aluminum hydroxide is replaced by an equal amount of γ-Al(OH)3 (grade HCW-101).

[0035] Test case The products prepared in the above embodiments and comparative examples were subjected to cavitation tests, and the test methods are as follows: The cavitation test was conducted using an ultrasonic material cavitation tester (compliant with ASTM G32), with a test frequency of 14 Hz and a test duration of 30 min.

[0036] Test results are available Figure 1-7 Therefore, it can be seen that Comparative Example 1 only used two relatively traditional fillers, molybdenum disulfide and iron oxide red, completely lacking PFA and crystalline aluminum hydroxide. The result was the worst cavitation resistance among all groups, proving that PTFE composites without the core components of this invention (PFA and crystalline aluminum hydroxide) cannot effectively resist cavitation damage, and the filler is prone to detachment. Comparative Example 2 added PFA but did not add aluminum hydroxide, with limited improvement. This indicates that although PFA can act as a binder to improve the overall integrity of the matrix, the lack of crystalline aluminum hydroxide, a key filler that provides strong interfacial bonding and high hardness, limits the improvement in cavitation resistance. Comparative Example 3 added aluminum hydroxide but did not add PFA, resulting in insufficient interfacial bonding in the finished material. This shows that although crystalline aluminum hydroxide has superior properties, without PFA as a bridge to enhance its bonding with the inert PTFE matrix, its advantages cannot be fully utilized, also leading to weak bonding and detachment. Comparative Examples 2 and 3 together reveal that the adhesive effect of PFA and the reinforcing and bonding effect of crystalline aluminum hydroxide are complementary. Although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0037] Therefore, the above description is only a preferred embodiment of this application and is not intended to limit the scope of this application; that is, all equivalent modifications made in accordance with the scope of the claims of this application shall be within the protection scope of the claims of this application.

Claims

1. A material for a cavitation-resistant bushing, characterized in that, It includes a metal base layer, a copper powder layer sintered on one side of the metal base layer, and a plastic layer embedded in and covering the copper powder layer. The plastic layer is prepared from the following components in parts by weight: 3-10 parts of molybdenum disulfide, 1-3 parts of iron oxide red, 5-10 parts of PFA, 3-10 parts of crystalline aluminum hydroxide, and 67-88 parts of PTFE emulsion.

2. The erosion resistant liner material of claim 1, wherein, The crystalline aluminum hydroxide is α-Al(OH)3.

3. The erosion resistant liner material of claim 1, wherein, The metal base layer is made of low-carbon steel.

4. The erosion resistant liner material of claim 1, wherein, The solid content of the PTFE emulsion is 55%-65%.

5. The method of producing an erosion-resistant bushing material according to any one of claims 1 to 4, wherein Includes the following steps: (1) CuSn8Zn3 spherical copper powder is evenly spread on a metal substrate. After sintering, a porous copper powder layer is formed on the metal substrate to obtain a copper powder plate. (2) Weigh molybdenum disulfide, iron oxide red, PFA and aluminum hydroxide according to the weight parts, mix them thoroughly to obtain a mixed dry powder; add the mixed dry powder to PTFE emulsion and continue stirring, then add alcohol to finely break the emulsion to form moist plastic particles; (3) The wet plastic particles are crushed and evenly sprinkled on the copper powder plate, and then the composite plate is obtained by rolling. (4) The composite board is dried, and then rolled a second time after drying; (5) The plate obtained in step (4) is sintered in a protective atmosphere and then rolled three times to obtain the cavitation resistant bushing material.

6. The production method according to claim 5, wherein In step (1), the sintering temperature is 890-910℃ and the sintering time is 40-60min.

7. The preparation method according to claim 5, characterized in that, In step (4), the drying temperature is 240-260℃ and the drying time is 4-8 min.

8. The preparation method according to claim 5, characterized in that, In step (5), the sintering temperature is 360-380℃ and the sintering time is 10-30min.

9. The preparation method according to claim 5, characterized in that, In step (4), the thickness of the plate after secondary rolling is 60-80 μm smaller than that of the dried plate.

10. The method of claim 5, wherein, In step (1), the porosity of the copper powder layer is 15%-30%.

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