Three-layer composite material for gear pump and preparation method thereof

Abstract

The application discloses a three-layer composite material for a gear pump and a preparation method thereof. The composite material comprises 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: calcium fluoride, ETFE, nano-aluminum oxide, graphite, iron red, and PTFE emulsion. ETFE is a tetrafluoroethylene-ethylene alternating copolymer. ETFE has a certain blending compatibility with the PTFE plastic matrix, and can form better bonding force in a sintered state. The calcium fluoride material has the characteristics of low-temperature brittleness and high-temperature plasticity. Under high-speed and high-load conditions, the high-plasticity calcium fluoride is easy to combine with PTFE under the influence of friction heat, and the transfer and consumption process can be more smooth, thereby improving the product performance. Through the cooperation of the components, the obtained plastic layer has high bonding strength, and the running time under continuous pressure durability test is significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of composite material preparation, and specifically relates to a three-layer composite material for gear pumps and its preparation method. Background Technology

[0002] With market development, the performance requirements for self-lubricating three-layer composite bearings in the gear pump field are becoming increasingly stringent. Overseas customers have reported that domestically produced three-layer composite bushings perform well in short-term operation, but are prone to failure during high-speed, long-term durability tests. The failure often involves cracking and peeling of the plastic layers, indicating insufficient bonding strength. Current domestic research in this field focuses on the bonding between the plastic layers and the substrate, as exemplified by CN202310049396.8. However, this often overlooks the bonding strength between the plastic layers. The fillers are often inorganic materials, such as graphite and molybdenum disulfide, which primarily reduce friction and wear on the base plastic. However, these fillers are largely non-reactive and have a certain inhibitory effect on the base plastic, hindering the bonding between the plastic layers. Yet, without fillers, the friction-reducing and wear-resistant properties of the plastic layers are insufficient to meet the requirements. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a three-layer composite material for gear pumps and its preparation method. The plastic layers in this composite material exhibit high bonding strength, resulting in a significantly improved operating time under continuous pressure durability testing.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A three-layer composite material for gear pumps includes a metal base layer, a copper powder layer sintered onto 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: 5-15 parts calcium fluoride, 5-15 parts ETFE, 3-7 parts nano-alumina, 1-5 parts graphite, 1-3 parts iron oxide red, and 65-75 parts PTFE emulsion. Preferably, the nano-alumina is γ-type nano-alumina; the metal base layer is a steel plate.

[0006] The present invention also provides a method for preparing the above-described three-layer composite material for gear pumps, comprising the following steps:

[0007] (1) Select low carbon steel plate as metal base layer, spread CuSn8Zn3 spherical copper powder evenly on low carbon steel plate, and sinter to form copper powder layer with a certain porosity to obtain copper powder plate; sintering temperature is 890-910℃ and sintering time is 40-60min.

[0008] (2) Weigh out 5-15 parts of dry calcium fluoride micro powder, 5-15 parts of ETFE micro powder, 3-7 parts of nano alumina, 1-5 parts of graphite, and 1-3 parts of iron oxide red according to the weight proportions. Stir using a mixer, stopping for 10-30 seconds after every 6-10 seconds of stirring to allow cooling and prevent agglomeration of the micro powder and nano powder. Repeat this process 3-7 times. Then weigh out 65-75 parts of PTFE emulsion and stir using a mixer. Add the evenly mixed dry powder during the stirring process and continue stirring for 5-15 minutes. Then weigh out 20-40 parts of alcohol to break the emulsion and form moist plastic particles.

[0009] (3) Dry the plastic particles in a box furnace at 50-70℃ for 7-13 minutes, ensuring that the edges of the plastic particles are not completely dry. Take out the plastic particles, squeeze and turn them over, and continue to dry them for 2-5 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into the crusher for crushing. The drying in this step has the following two functions: First, moderate drying makes it easier for the crusher to crush the particles, forming a mud material containing a trace of moisture, which is convenient for subsequent rolling steps and control of precision (it is more difficult to roll into the gaps of the copper powder plate and control the dimensional precision if it is completely dried into a dry mud state); Second, it controls the moisture as much as possible, which makes it easier to dry completely in the subsequent step (5). If the drying is not complete, the moisture will also evaporate during sintering. The moisture may cause defects such as holes in the plastic in the sintered state. Even if it is rolled again after sintering and cooling, the holes will not be completely bonded in the cooled state, which may become fatigue crack propagation sources.

[0010] (4) Sprinkle crushed plastic particles onto the copper powder plate and then perform compounding by rolling mill with adjusted dimensions;

[0011] (5) The composite plate is dried in a mesh belt furnace with a set temperature and time of 240-260℃ and 4-8min. After completion, it is further dried in a rolling mill with adjusted dimensions. The thickness of the rolled plate is required to be 20-40μm larger than the thickness of the finished product.

[0012] (6) Continue to put the plate into a nitrogen-filled box furnace for sintering at a temperature of 360-380℃ for 10-30 minutes. After completion, continue to roll it to the finished size through a rolling mill with the dimensions adjusted.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] (1) This invention improves the bonding strength and operating time of the plastic layer by introducing ETFE micropowder. ETFE is a tetrafluoroethylene-ethylene alternating copolymer, which has certain compatibility with the PTFE plastic matrix and can form better bonding force in the sintered state. Moreover, due to the characteristics of its composition, the melting point of ETFE is mostly between 250 and 270°C, which is lower than that of PTFE (327°C). In the sintered state, it has higher fluidity and can better coat and bond other inorganic fillers, thereby improving the overall bonding force. In addition, the presence of amorphous regions in ETFE material enables the impact strength of ETFE to reach 90 J / m, which is superior to PTFE material in all aspects of mechanical strength. In addition to being continuously subjected to load, the bushing of the high-pressure gear pump is also subjected to the scouring of lubricating oil in different directions. The introduction of high-impact strength ETFE can significantly resist the initiation and propagation of cracks, improve the fatigue resistance of the material, and extend the operating time.

[0015] (2) This invention improves product performance by introducing calcium fluoride micro powder. Calcium fluoride material has the characteristics of low-temperature brittleness and high-temperature plasticity. Under high-speed and high-load conditions, under the influence of frictional heat, the highly plastic calcium fluoride is easy to combine with PTFE, and the transfer and consumption process can be smoother. This avoids the peeling caused by other inorganic fillers due to poor bonding with the matrix. The peeling site is easy to become the initiation source of cracks, which leads to fatigue crack propagation and fatigue failure.

[0016] (3) The nano-alumina introduced in this invention is γ-type nano-alumina, which is an active alumina with high specific surface area, high porosity, strong heat resistance and formability. Its specific surface area is usually several times larger than that of ordinary alumina, and its high porosity can also be mechanically bonded to PTFE, making the bonding more complete. Detailed Implementation

[0017] The present invention will be further described below with reference to embodiments, so that those skilled in the art can better understand and implement the present invention, but the embodiments are not intended to limit the present invention.

[0018] In addition, unless otherwise specified, the preparation processes in the following embodiments are all conventional methods in the prior art, and therefore will not be described in detail; the parts in the following embodiments refer to parts by weight; the raw materials used are all commercially available products.

[0019] Example 1

[0020] A method for preparing a three-layer composite material for a gear pump, comprising the following steps:

[0021] (1) CuSn8Zn3 spherical copper powder is evenly spread on a low carbon steel plate and sintered to form a copper powder layer with a certain porosity, and a copper powder plate is obtained. The sintering temperature is 900℃ and the sintering time is 50min.

[0022] (2) Weigh out 10 parts by weight of dry calcium fluoride micro powder, 10 parts by weight of ETFE micro powder, 5 parts by weight of γ-type nano alumina, 3 parts by weight of graphite, and 2 parts by weight of iron oxide. Stir with a mixer, stopping for 20 seconds after every 8 seconds of stirring to allow cooling and prevent agglomeration of the micro powder and nano powder. Repeat this process 5 times. Then weigh out 70 parts by weight of PTFE emulsion and stir with a mixer. Add the well-mixed dry powder during the stirring process and continue stirring for 10 minutes. Then weigh out 30 parts by weight of alcohol to break the emulsion and form moist plastic particles.

[0023] (3) Dry the plastic particles in a box furnace at 60°C for 10 minutes to ensure that the edges of the plastic particles are not completely dry. Take out the plastic particles, squeeze and turn them over, and continue to dry them for 3 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into the crusher for crushing.

[0024] (4) Sprinkle crushed plastic particles onto the copper powder plate and then perform compounding by rolling mill with adjusted dimensions;

[0025] (5) 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 further dried in a rolling mill with the dimensions adjusted. The thickness of the rolled plate is 30μm larger than the thickness of the finished product.

[0026] (6) 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.

[0027] Example 2

[0028] A method for preparing a three-layer composite material for a gear pump, comprising the following steps:

[0029] (1) CuSn8Zn3 spherical copper powder is evenly spread on a low carbon steel plate and sintered to form a copper powder layer with a certain porosity, and a copper powder plate is obtained. The sintering temperature is 890℃ and the sintering time is 60min.

[0030] (2) Weigh out 5 parts of dry calcium fluoride micro powder, 15 parts of ETFE micro powder, 7 parts of γ-type nano alumina, 5 parts of graphite, and 3 parts of iron oxide according to the weight proportions. Stir with a mixer, stopping for 10 seconds after every 6 seconds of stirring to allow cooling and prevent agglomeration of the micro powder and nano powder. Repeat this process 7 times. Then weigh out 65 parts of PTFE emulsion and stir with a mixer. Add the evenly mixed dry powder during the stirring process. After stirring for 5 minutes, weigh out 20 parts of alcohol to break the emulsion and form moist plastic particles.

[0031] (3) Dry the plastic particles in a box furnace at 50°C for 13 minutes, ensuring that the edges of the plastic particles are not completely dry. Take out the plastic particles, squeeze and turn them over, and continue to dry them for 5 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into the crusher for crushing.

[0032] (4) Sprinkle crushed plastic particles onto the copper powder plate and then perform compounding by rolling mill with adjusted dimensions;

[0033] (5) 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 further dried in a rolling mill with the dimensions adjusted. The thickness of the rolled plate is 40μm larger than the thickness of the finished product.

[0034] (6) 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 it to the finished size through a rolling mill with the dimensions adjusted.

[0035] Example 3

[0036] A method for preparing a three-layer composite material for a gear pump, comprising the following steps:

[0037] (1) CuSn8Zn3 spherical copper powder is evenly spread on a low carbon steel plate and sintered to form a copper powder layer with a certain porosity, and a copper powder plate is obtained. The sintering temperature is 910℃ and the sintering time is 40min.

[0038] (2) Weigh out 15 parts of dry calcium fluoride micro powder, 5 parts of ETFE micro powder, 3 parts of γ-type nano alumina, 1 part of graphite, and 1 part of iron oxide red according to the weight proportions. Stir with a mixer, stopping for 30 seconds after every 10 seconds of stirring to allow cooling and prevent agglomeration of the micro powder and nano powder. Repeat this process 3 times. Then weigh out 75 parts of PTFE emulsion and stir with a mixer. Add the evenly mixed dry powder during the stirring process. After stirring for 15 minutes, weigh out 40 parts of alcohol to break the emulsion and form moist plastic particles.

[0039] (3) Dry the plastic particles in a box furnace at 70°C for 7 minutes to ensure that the edges of the plastic particles are not completely dry. Take out the plastic particles, squeeze and turn them over, and continue to dry them for 2 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into the crusher for crushing.

[0040] (4) Sprinkle crushed plastic particles onto the copper powder plate and then perform compounding by rolling mill with adjusted dimensions;

[0041] (5) 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 in a rolling mill with the dimensions adjusted. The thickness of the rolled plate is 20μm larger than the thickness of the finished product.

[0042] (6) Continue to put the plate into a nitrogen-filled box furnace for sintering at a temperature of 380°C for 10 minutes. After completion, continue to roll it to the finished size through a rolling mill with the dimensions adjusted.

[0043] Comparative Example 1:

[0044] A method for preparing a three-layer composite material for a gear pump, comprising the following steps:

[0045] (1) CuSn8Zn3 spherical copper powder is evenly spread on a low carbon steel plate and sintered to form a copper powder layer with a certain porosity, and a copper powder plate is obtained. The sintering temperature is 900℃ and the sintering time is 50min.

[0046] (2) Weigh 15 parts of dry graphite powder and 15 parts of iron oxide red according to the weight proportions. Stir with a mixer, stopping for 20 seconds after every 8 seconds of stirring to allow cooling and prevent agglomeration of micro and nano powders. Repeat this process 5 times. Then weigh 70 parts of PTFE emulsion and stir with a mixer. Add the well-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.

[0047] (3) Dry the plastic particles in a box furnace at 60°C for 10 minutes to ensure that the edges of the plastic particles are not completely dry. Take out the plastic particles, squeeze and turn them over, and continue to dry them for 3 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into the crusher for crushing.

[0048] (4) Sprinkle crushed plastic particles onto the copper powder plate and then perform compounding by rolling mill with adjusted dimensions;

[0049] (5) 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 further dried in a rolling mill with the dimensions adjusted. The thickness of the rolled plate is 30μm larger than the thickness of the finished product.

[0050] (6) 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.

[0051] Comparative Example 2:

[0052] A method for preparing a three-layer composite material for a gear pump, comprising the following steps:

[0053] (1) CuSn8Zn3 spherical copper powder is evenly spread on a low carbon steel plate and sintered to form a copper powder layer with a certain porosity, and a copper powder plate is obtained. The sintering temperature is 900℃ and the sintering time is 50min.

[0054] (2) Weigh out 5 parts of dry γ-type nano alumina powder, 15 parts of graphite, and 10 parts of iron oxide red according to the weight proportions. Stir with a mixer, stopping for 20 seconds after every 8 seconds of stirring to allow cooling and prevent agglomeration of micro and nano powders. Repeat this process 5 times. Then weigh out 70 parts of PTFE emulsion and stir with 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.

[0055] (3) Dry the plastic particles in a box furnace at 60°C for 10 minutes to ensure that the edges of the plastic particles are not completely dry. Take out the plastic particles, squeeze and turn them over, and continue to dry them for 3 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into the crusher for crushing.

[0056] (4) Sprinkle crushed plastic particles onto the copper powder plate and then perform compounding by rolling mill with adjusted dimensions;

[0057] (5) 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 further dried in a rolling mill with the dimensions adjusted. The thickness of the rolled plate is 30μm larger than the thickness of the finished product.

[0058] (6) 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.

[0059] Comparative Example 3:

[0060] A method for preparing a three-layer composite material for a gear pump, comprising the following steps:

[0061] (1) CuSn8Zn3 spherical copper powder is evenly spread on a low carbon steel plate and sintered to form a copper powder layer with a certain porosity, and a copper powder plate is obtained. The sintering temperature is 900℃ and the sintering time is 50min.

[0062] (2) Weigh out 10 parts of dry ETFE micro powder, 10 parts of graphite, and 10 parts of iron oxide red according to the weight proportions. Stir with a mixer, stopping for 20 seconds after every 8 seconds of stirring to allow cooling and prevent agglomeration of the micro powder and nano powder. Repeat this process 5 times. Then weigh out 70 parts of PTFE emulsion and stir with a mixer. Add the well-mixed dry powder during the stirring process and continue stirring for 10 minutes. Then weigh out 30 parts of alcohol to break the emulsion and form moist plastic particles.

[0063] (3) Dry the plastic particles in a box furnace at 60°C for 10 minutes to ensure that the edges of the plastic particles are not completely dry. Take out the plastic particles, squeeze and turn them over, and continue to dry them for 3 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into the crusher for crushing.

[0064] (4) Sprinkle crushed plastic particles onto the copper powder plate and then perform compounding by rolling mill with adjusted dimensions;

[0065] (5) 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 further dried in a rolling mill with the dimensions adjusted. The thickness of the rolled plate is 30μm larger than the thickness of the finished product.

[0066] (6) 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.

[0067] Comparative Example 4:

[0068] A method for preparing a three-layer composite material for a gear pump, comprising the following steps:

[0069] (1) CuSn8Zn3 spherical copper powder is evenly spread on a low carbon steel plate and sintered to form a copper powder layer with a certain porosity, and a copper powder plate is obtained. The sintering temperature is 900℃ and the sintering time is 50min.

[0070] (2) Weigh out 10 parts of dry calcium fluoride micro powder, 10 parts of graphite, and 10 parts of iron oxide red according to the weight proportions. Stir with a mixer, stopping for 20 seconds after every 8 seconds of stirring to allow cooling and prevent agglomeration of the micro powder and nano powder. Repeat this process 5 times. Then weigh out 70 parts of PTFE emulsion and stir with a mixer. Add the well-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.

[0071] (3) Dry the plastic particles in a box furnace at 60°C for 10 minutes to ensure that the edges of the plastic particles are not completely dry. Take out the plastic particles, squeeze and turn them over, and continue to dry them for 3 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into the crusher for crushing.

[0072] (4) Sprinkle crushed plastic particles onto the copper powder plate and then perform compounding by rolling mill with adjusted dimensions;

[0073] (5) 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 further dried in a rolling mill with the dimensions adjusted. The thickness of the rolled plate is 30μm larger than the thickness of the finished product.

[0074] (6) 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.

[0075] Comparative Example 5:

[0076] A method for preparing a three-layer composite material for a gear pump, comprising the following steps:

[0077] (1) CuSn8Zn3 spherical copper powder is evenly spread on a low carbon steel plate and sintered to form a copper powder layer with a certain porosity, and a copper powder plate is obtained. The sintering temperature is 900℃ and the sintering time is 50min.

[0078] (2) Weigh out 10 parts of dry ETFE micro powder, 5 parts of γ-type nano alumina, 10 parts of graphite, and 5 parts of iron oxide according to the weight proportions. Stir with a mixer, stopping for 20 seconds after every 8 seconds of stirring to allow cooling and prevent agglomeration of the micro powder and nano powder. Repeat this process 5 times. Then weigh out 70 parts of PTFE emulsion and stir with a mixer. Add the well-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.

[0079] (3) Dry the plastic particles in a box furnace at 60°C for 10 minutes to ensure that the edges of the plastic particles are not completely dry. Take out the plastic particles, squeeze and turn them over, and continue to dry them for 3 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into the crusher for crushing.

[0080] (4) Sprinkle crushed plastic particles onto the copper powder plate and then perform compounding by rolling mill with adjusted dimensions;

[0081] (5) 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 further dried in a rolling mill with the dimensions adjusted. The thickness of the rolled plate is 30μm larger than the thickness of the finished product.

[0082] (6) 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.

[0083] Comparative Example 6:

[0084] A method for preparing a three-layer composite material for a gear pump, comprising the following steps:

[0085] (1) CuSn8Zn3 spherical copper powder is evenly spread on a low carbon steel plate and sintered to form a copper powder layer with a certain porosity, and a copper powder plate is obtained. The sintering temperature is 900℃ and the sintering time is 50min.

[0086] (2) Weigh out 10 parts of dry calcium fluoride micro powder, 5 parts of γ-type nano alumina, 10 parts of graphite, and 5 parts of iron oxide red according to the weight proportions. Stir with a mixer, stopping for 20 seconds after every 8 seconds of stirring to allow cooling and prevent the micro powder and nano powder from agglomerating. Repeat this process 5 times. Then weigh out 70 parts of PTFE emulsion and stir with 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.

[0087] (3) Dry the plastic particles in a box furnace at 60°C for 10 minutes to ensure that the edges of the plastic particles are not completely dry. Take out the plastic particles, squeeze and turn them over, and continue to dry them for 3 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into the crusher for crushing.

[0088] (4) Sprinkle crushed plastic particles onto the copper powder plate and then perform compounding by rolling mill with adjusted dimensions;

[0089] (5) 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 further dried in a rolling mill with the dimensions adjusted. The thickness of the rolled plate is 30μm larger than the thickness of the finished product.

[0090] (6) 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.

[0091] Comparative Example 7:

[0092] A method for preparing a three-layer composite material for a gear pump, comprising the following steps:

[0093] (1) CuSn8Zn3 spherical copper powder is evenly spread on a low carbon steel plate and sintered to form a copper powder layer with a certain porosity, and a copper powder plate is obtained. The sintering temperature is 900℃ and the sintering time is 50min.

[0094] (2) Weigh out 10 parts of dry calcium fluoride micro powder, 10 parts of ETFE micro powder, 5 parts of graphite, and 5 parts of iron oxide red according to the weight proportions. Stir with a mixer, stopping for 20 seconds after every 8 seconds of stirring to allow cooling and prevent agglomeration of the micro powder and nano powder. Repeat this process 5 times. Then weigh out 70 parts of PTFE emulsion and stir with 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.

[0095] (3) Dry the plastic particles in a box furnace at 60°C for 10 minutes to ensure that the edges of the plastic particles are not completely dry. Take out the plastic particles, squeeze and turn them over, and continue to dry them for 3 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into the crusher for crushing.

[0096] (4) Sprinkle crushed plastic particles onto the copper powder plate and then perform compounding by rolling mill with adjusted dimensions;

[0097] (5) 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 further dried in a rolling mill with the dimensions adjusted. The thickness of the rolled plate is 30μm larger than the thickness of the finished product.

[0098] (6) 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.

[0099] Performance Tests and Results

[0100] The products prepared in the above embodiments and comparative examples were subjected to performance tests, and the test methods are as follows:

[0101] The strength test was conducted according to GB / T 5210, using a single test column from one side. Prior to the test, the surface plastic layer was treated with sodium-naphthalene. The diameter of the test column was... The tensile testing machine speed is 60 mm / min.

[0102] The running time is for durability testing, and the test is conducted with reference to the equipment and related parameters in GB / T 7948. Continuous pressure durability testing is performed at 18 MPa / 3000 rpm / 80℃.

[0103] The test results are shown in Table 1.

[0104] Table 1. Performance test results of the products prepared in each embodiment and comparative example.

[0105] Material Bond strength (MPa) Running time (h) Comparative Example 1 3.17 179 Comparative Example 2 3.54 243 Comparative Example 3 4.91 287 Comparative Example 4 3.99 313 Comparative Example 5 6.13 389 Comparative Example 6 5.16 364 Comparative Example 7 5.77 407 Example 1 8.02 ＞500 Example 2 8.34 ＞500 Example 3 7.83 ＞500

[0106] Comparative Examples 1-7 are comparison examples of Example 1 using the same process but different formulations, mainly to verify the bonding strength and operating time under continuous pressure durability testing. Table 1 above shows that graphite + iron powder has a negative impact on the bonding strength of the plastic layer; the higher the content, the lower the bonding strength. As the graphite + iron powder content decreased, and ETFE, alumina, and calcium fluoride were added instead, the bonding strength was improved positively, and the operating time under continuous pressure durability testing also gradually increased.

[0107] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A three-layer composite material for a gear pump, 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: 5-15 parts calcium fluoride, 5-15 parts ETFE, 3-7 parts nano alumina, 1-5 parts graphite, 1-3 parts iron oxide red, and 65-75 parts PTFE emulsion.

2. The three-layer composite material for gear pumps according to claim 1, characterized in that: The nano-alumina is γ-type nano-alumina.

3. The three-layer composite material for gear pumps according to claim 1, characterized in that: The metal base layer is a steel plate.

4. The method for preparing the three-layer composite material for gear pumps according to any one of claims 1 to 3, characterized in that: Includes the following steps: (1) CuSn8Zn3 spherical copper powder is evenly spread on a metal substrate. After sintering, a copper powder layer with a certain porosity is formed on the metal substrate, and a copper powder plate is obtained. (2) Weigh out 5-15 parts of calcium fluoride, 5-15 parts of ETFE, 3-7 parts of nano alumina, 1-5 parts of graphite, and 1-3 parts of iron oxide according to the weight of the components, stir evenly to obtain a mixed dry powder; add 65-75 parts of PTFE emulsion to the mixed dry powder and continue stirring, then add alcohol to finely break the emulsion to form moist plastic particles. (3) Heat the wet plastic particles to dry them appropriately. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into the crusher for crushing. (4) Sprinkle crushed plastic particles onto the copper powder plate and then composite it using a rolling mill; (5) The composite plate is placed in a mesh belt furnace for drying. After drying, it is rolled by a rolling mill. The thickness of the rolled size is required to be 20-40μm larger than the thickness of the finished product. (6) The sheet is sintered in a protective atmosphere and then rolled to the finished size by a rolling mill.

5. The method for preparing the three-layer composite material for gear pumps according to claim 4, characterized in that: In step (1), the sintering temperature is 890-910℃ and the sintering time is 40-60min.

6. The method for preparing the three-layer composite material for gear pumps according to claim 4, characterized in that: In step (3), the heating temperature is 50-70℃.

7. The method for preparing the three-layer composite material for gear pumps according to claim 4, characterized in that: In step (5), the drying temperature is 240-260℃ and the drying time is 4-8 minutes.

8. The method for preparing the three-layer composite material for gear pumps according to claim 4, characterized in that: In step (6), the sintering temperature is 360-380℃ and the sintering time is 10-30min.