Three-layer composite material for gear pump and preparation method of three-layer composite material

Abstract

The invention discloses a three-layer composite material for a gear pump and a preparation method of the three-layer composite material, 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, and the plastic layer is prepared from calcium fluoride, ETFE, nanometer aluminum oxide, graphite, iron oxide red and PTFE emulsion. ETFE is a tetrafluoroethylene-ethylene alternating copolymer, the ETFE and a PTFE plastic matrix have certain blending compatibility, and better binding force can be formed in a sintering state; the calcium fluoride material has the characteristics of low-temperature brittleness and high-temperature plasticity, under the high-speed and high-load condition and under the influence of friction heat, the high-plasticity calcium fluoride is easily combined with PTFE, the transfer and consumption process can be smoother, and therefore the product performance is improved; through cooperative use of all the components, the obtained plastic layer is high in bonding strength, and the running time under a continuous pressure durability test is remarkably prolonged.

Description

Technical Field

[0001] The invention belongs to the field of composite material preparation, and particularly relates to a three-layer composite material for a gear pump and a preparation method thereof. Background Art

[0002] With the development of the market, the performance requirements of self-lubricating three-layer composite bearings in the field of gear pumps are getting higher and higher. Foreign customers have reported that domestic three-layer composite sleeve products can run for a short time, but are prone to failure during high-speed and long-term durability tests. The failure form is often accompanied by cracking and peeling of the plastic layer. Cracking and peeling mean that the bonding force is insufficient. At present, domestic research in this field has been focusing on the bonding between the plastic layer and the substrate, such as CN202310049396.8. However, this often ignores the bonding strength between plastic layers, because the fillers are often some inorganic materials, such as graphite, molybdenum disulfide, etc., most of which have the effect of reducing friction and wear on the base plastic, but these fillers basically do not react, and have a certain separatist effect on the base plastic, which is not conducive to the bonding between plastic layers, but lack of fillers, the friction reduction and wear resistance of the plastic layer is difficult to meet the demand. Summary of the invention

[0003] To address the deficiencies of the prior art, the present invention aims to provide a three-layer composite material for a gear pump and a preparation method thereof, wherein the plastic layers in the composite material have high bonding strength and the operating time under a continuous pressure durability test is significantly improved.

[0004] The objective of the present invention is achieved through the following technical solutions:

[0005] A three-layer composite material for a gear pump, the composite material comprising a metal base, a copper powder layer sintered on one side of the metal base, and a plastic layer embedded in and covering the copper powder layer, wherein the plastic layer is prepared from the following components by weight: 5-15 parts of calcium fluoride, 5-15 parts of ETFE, 3-7 parts of nano-alumina, 1-5 parts of graphite, 1-3 parts of iron oxide red, and 65-75 parts of PTFE emulsion. Preferably, the nano-alumina is γ-type nano-alumina; and the metal base is a steel plate.

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

[0007] (1) Selecting a low-carbon steel plate as the metal base, evenly laying the CuSn8Zn3 spherical copper powder on the low-carbon steel plate, sintering to form a copper powder layer with a certain porosity, and obtaining a copper powder plate; the sintering temperature is 890-910°C, and the sintering time is 40-60min;

[0008] (2) According to the weight of the components, weigh 5-15 parts of dry powder calcium fluoride micropowder, 5-15 parts of ETFE micropowder, 3-7 parts of nano-alumina, 1-5 parts of graphite, and 1-3 parts of iron red, and stir them in a stirrer. After stirring for 6-10 seconds, stop for 10-30 seconds to wait for cooling to prevent the micropowder and nanopowder from agglomerating. Continue for 3-7 times. Then weigh 65-75 parts of PTFE emulsion, stir it in a stirrer, add the dry powder that is evenly mixed during the stirring process, continue stirring for 5-15 minutes, and weigh 20-40 parts of alcohol to break the emulsion to form wet plastic particles.

[0009] (3) Dry the plastic particles in a box furnace at 50-70°C for 7-13 minutes to ensure that the edges of the plastic particles are not completely dried. Take out the plastic particles, squeeze and flip them, and continue drying for 2-5 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into a crusher for crushing. The drying in this step has the following two effects: first, it is convenient for the crusher to crush after moderate drying, and it can form a crushed mud material with a trace of water, which is convenient for the subsequent rolling step and control accuracy (complete drying into dry mud is more difficult to roll into the gap of the copper powder plate and control the size accuracy); second, the moisture is controlled as much as possible to facilitate the complete drying in the subsequent step (5). In the case of incomplete drying, the moisture will evaporate during sintering, and the moisture may cause defects such as holes in the plastic in the sintered state. Even if it will be rolled after sintering and cooling, the holes will not be completely bonded in the cooling state, which may become the source of fatigue crack extension.

[0010] (4) Sprinkle crushed plastic particles on the copper powder plate and compound them through a rolling mill with adjusted size;

[0011] (5) The composite plate is dried in a mesh belt furnace with set temperature and time, the temperature is 240-260°C, the time is 4-8 minutes, and then it is continued to pass through a rolling mill with adjusted size. The rolling size thickness is 20-40 μm larger than the finished product thickness requirement;

[0012] (6) Continue to place the plate in a nitrogen-filled box furnace for sintering at a temperature of 360-380°C for 10-30 minutes. After completion, continue to pass through a rolling mill with adjusted dimensions to roll to the finished product size;

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] (1) The present 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 a certain blending compatibility with the PTFE plastic matrix and can form better bonding force in the sintered state. Moreover, due to the characteristics of the composition, the melting point of ETFE is mostly between 250 and 270°C, which is lower than 327°C of PTFE. It has higher fluidity in the sintered state of the material and can better coat and bond other inorganic fillers to improve the overall bonding force. In addition, the presence of amorphous regions in the ETFE material enables the impact strength of ETFE to reach 90J / m, and its mechanical strength is superior to that of PTFE materials in all aspects. In addition to being continuously loaded, the shaft sleeve in the high-pressure gear pump is also eroded by lubricating oil in different directions. The introduction of ETFE with high impact strength can significantly resist the initiation and expansion of cracks, improve the material's fatigue resistance, and extend the operating time.

[0015] (2) The present invention improves product performance by introducing calcium fluoride 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, avoiding the peeling caused by other inorganic fillers due to weak bonding with the matrix. The peeling position is easy to become the source of crack initiation, thereby causing fatigue crack expansion and further fatigue failure.

[0016] (3) The nano-alumina introduced in the present invention is γ-type nano-alumina, which is an active alumina with high specific surface area, high porosity, strong heat resistance and formability. The specific surface area is usually several times larger than that of ordinary alumina, and the high porosity can also be combined with PTFE by mechanical means, making the combination more complete. DETAILED DESCRIPTION

[0017] The present invention is further described below in conjunction with the embodiments so that those skilled in the art can better understand the present invention and implement it, 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 means in the prior art in the art, and therefore, they are not described in detail; the parts in the following embodiments are all parts by weight; the raw materials used are all commercially available products and can be purchased commercially.

[0019] Example 1

[0020] A method for preparing a three-layer composite material for a gear pump, the steps of which are as follows:

[0021] (1) CuSn8Zn3 spherical copper powder is evenly laid on a low-carbon steel plate and sintered to form a copper powder layer with a certain porosity to obtain a copper powder plate. The sintering temperature is 900°C and the sintering time is 50 min.

[0022] (2) According to the weight of the components, 10 parts of dry powder calcium fluoride micropowder, 10 parts of ETFE micropowder, 5 parts of γ-type nano-alumina, 3 parts of graphite, and 2 parts of iron red were weighed and stirred using a mixer. After every 8 seconds of stirring, the mixture was stopped for 20 seconds to wait for cooling to prevent the micropowder and nanopowder from agglomerating. This was repeated for 5 times. Then 70 parts of PTFE emulsion were weighed and stirred using a mixer. During the stirring process, the dry powder was added and mixed evenly. After continuous stirring for 10 minutes, 30 parts of alcohol was weighed to break the emulsion and form wet 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 drying for 3 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into a crusher for crushing.

[0024] (4) Sprinkle crushed plastic particles on the copper powder plate and compound them through a rolling mill with adjusted size;

[0025] (5) The composite plate is dried in a mesh belt furnace with set temperature and time, the temperature is 250°C, the time is 6 minutes, and then it is continued to pass through a rolling mill with adjusted size. The rolling size thickness is 30 μm larger than the finished product thickness requirement;

[0026] (6) The plate is then placed in a nitrogen-filled box furnace for sintering at a temperature of 370°C for 20 min. After sintering, the plate is rolled into the finished product size through a rolling mill with the size adjusted.

[0027] Example 2

[0028] A method for preparing a three-layer composite material for a gear pump, the steps of which are as follows:

[0029] (1) CuSn8Zn3 spherical copper powder is evenly laid on a low-carbon steel plate and sintered to form a copper powder layer with a certain porosity to obtain a copper powder plate. The sintering temperature is 890°C and the sintering time is 60 min.

[0030] (2) Weigh 5 parts of dry powder calcium fluoride micropowder, 15 parts of ETFE micropowder, 7 parts of γ-type nano-alumina, 5 parts of graphite, and 3 parts of iron red according to the weight of the components, and stir them using a mixer. After stirring for 6 seconds, stop for 10 seconds to wait for cooling to prevent the micropowder and nanopowder from agglomerating. Continue for 7 times. Then weigh 65 parts of PTFE emulsion and stir it using a mixer. During the stirring process, add the evenly mixed dry powder. After stirring for 5 minutes, weigh 20 parts of alcohol to break the emulsion to form wet plastic particles.

[0031] (3) Dry the plastic particles in a box furnace at 50°C for 13 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 drying for 5 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into a crusher for crushing.

[0032] (4) Sprinkle crushed plastic particles on the copper powder plate and compound them through a rolling mill with adjusted size;

[0033] (5) The composite plate is dried in a mesh belt furnace with set temperature and time, the temperature is 240°C, the time is 8 minutes, and then it is continued to pass through a rolling mill with adjusted size. The rolling size thickness is 40 μm larger than the finished product thickness requirement;

[0034] (6) Continue to place the plate in a nitrogen-filled box furnace for sintering at a temperature of 360°C for 30 minutes. After completion, continue to pass through a rolling mill with adjusted dimensions to roll to the finished product size;

[0035] Example 3

[0036] A method for preparing a three-layer composite material for a gear pump, the steps of which are as follows:

[0037] (1) CuSn8Zn3 spherical copper powder is evenly laid on a low-carbon steel plate and sintered to form a copper powder layer with a certain porosity to obtain a copper powder plate. The sintering temperature is 910°C and the sintering time is 40 min.

[0038] (2) According to the weight of the components, 15 parts of dry powder calcium fluoride micropowder, 5 parts of ETFE micropowder, 3 parts of γ-type nano-alumina, 1 part of graphite, and 1 part of iron red were weighed and stirred using a mixer. After every 10 seconds of stirring, the mixture was stopped for 30 seconds to wait for cooling to prevent the micropowder and nanopowder from agglomerating. This was repeated for 3 times. Then 75 parts of PTFE emulsion were weighed and stirred using a mixer. During the stirring process, the dry powder was added and mixed evenly. After continuous stirring for 15 minutes, 40 parts of alcohol were weighed to break the emulsion and form wet 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 drying for 2 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into a crusher for crushing.

[0040] (4) Sprinkle crushed plastic particles on the copper powder plate and compound them through a rolling mill with adjusted size;

[0041] (5) The composite plate is dried in a mesh belt furnace with set temperature and time, the temperature is 260°C, the time is 4 minutes, and then it is continued to pass through a rolling mill with adjusted size. The rolling size thickness is 20 μm larger than the finished product thickness requirement;

[0042] (6) The plate is then placed in a nitrogen-filled box furnace for sintering at a temperature of 380°C for 10 min. After sintering, the plate is rolled into the finished product size through a rolling mill with the size adjusted.

[0043] Comparative Example 1:

[0044] A method for preparing a three-layer composite material for a gear pump, the steps of which are as follows:

[0045] (1) CuSn8Zn3 spherical copper powder is evenly laid on a low-carbon steel plate and sintered to form a copper powder layer with a certain porosity to obtain a copper powder plate. The sintering temperature is 900°C and the sintering time is 50 min.

[0046] (2) Weigh 15 parts of dry powdered graphite and 15 parts of iron oxide according to the weight of the components, and stir them in a stirrer. After stirring for 8 seconds, stop for 20 seconds to wait for cooling to prevent the micro-powder and nano-powder from agglomerating. Repeat this process for 5 times. Then weigh 70 parts of PTFE emulsion and stir it in a stirrer. During the stirring process, add the dry powder that has been mixed evenly. After stirring for 10 minutes, weigh 30 parts of alcohol to break the emulsion and form wet 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 drying for 3 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into a crusher for crushing.

[0048] (4) Sprinkle crushed plastic particles on the copper powder plate and compound them through a rolling mill with adjusted size;

[0049] (5) The composite plate is dried in a mesh belt furnace with set temperature and time, the temperature is 250°C, the time is 6 minutes, and then it is continued to pass through a rolling mill with adjusted size. The rolling size thickness is 30 μm larger than the finished product thickness requirement;

[0050] (6) The plate is then placed in a nitrogen-filled box furnace for sintering at a temperature of 370°C for 20 min. After sintering, the plate is rolled into the finished product size through a rolling mill with the size adjusted.

[0051] Comparative Example 2:

[0052] A method for preparing a three-layer composite material for a gear pump, the steps of which are as follows:

[0053] (1) CuSn8Zn3 spherical copper powder is evenly laid on a low-carbon steel plate and sintered to form a copper powder layer with a certain porosity to obtain a copper powder plate. The sintering temperature is 900°C and the sintering time is 50 min.

[0054] (2) According to the weight of the components, 5 parts of dry powder γ-type nano-alumina, 15 parts of graphite, and 10 parts of iron red were weighed and stirred using a mixer. After stirring for 8 seconds, the mixture was stopped for 20 seconds to wait for cooling to prevent the micro-powder and nano-powder from agglomerating. This was repeated for 5 times. Then 70 parts of PTFE emulsion were weighed and stirred using a mixer. During the stirring process, the dry powder was added and mixed evenly. After stirring for 10 minutes, 30 parts of alcohol was weighed to break the emulsion and form wet 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 drying for 3 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into a crusher for crushing.

[0056] (4) Sprinkle crushed plastic particles on the copper powder plate and compound them through a rolling mill with adjusted size;

[0057] (5) The composite plate is dried in a mesh belt furnace with set temperature and time, the temperature is 250°C, the time is 6 minutes, and then it is continued to pass through a rolling mill with adjusted size. The rolling size thickness is 30 μm larger than the finished product thickness requirement;

[0058] (6) The plate is then placed in a nitrogen-filled box furnace for sintering at a temperature of 370°C for 20 min. After sintering, the plate is rolled into the finished product size through a rolling mill with the size adjusted.

[0059] Comparative Example 3:

[0060] A method for preparing a three-layer composite material for a gear pump, the steps of which are as follows:

[0061] (1) CuSn8Zn3 spherical copper powder is evenly laid on a low-carbon steel plate and sintered to form a copper powder layer with a certain porosity to obtain a copper powder plate. The sintering temperature is 900°C and the sintering time is 50 min.

[0062] (2) According to the weight of the components, 10 parts of dry ETFE micropowder, 10 parts of graphite, and 10 parts of iron red were weighed and stirred using a mixer. After stirring for 8 seconds, the mixture was stopped for 20 seconds to wait for cooling to prevent the micropowder and nanopowder from agglomerating. This was repeated for 5 times. Then 70 parts of PTFE emulsion were weighed and stirred using a mixer. During the stirring process, the dry powder was added and mixed evenly. After stirring for 10 minutes, 30 parts of alcohol was weighed to break the emulsion and form wet 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 drying for 3 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into a crusher for crushing.

[0064] (4) Sprinkle crushed plastic particles on the copper powder plate and compound them through a rolling mill with adjusted size;

[0065] (5) The composite plate is dried in a mesh belt furnace with set temperature and time, the temperature is 250°C, the time is 6 minutes, and then it is continued to pass through a rolling mill with adjusted size. The rolling size thickness is 30 μm larger than the finished product thickness requirement;

[0066] (6) The plate is then placed in a nitrogen-filled box furnace for sintering at a temperature of 370°C for 20 min. After sintering, the plate is rolled into the finished product size through a rolling mill with the size adjusted.

[0067] Comparative Example 4:

[0068] A method for preparing a three-layer composite material for a gear pump, the steps of which are as follows:

[0069] (1) CuSn8Zn3 spherical copper powder is evenly laid on a low-carbon steel plate and sintered to form a copper powder layer with a certain porosity to obtain a copper powder plate. The sintering temperature is 900°C and the sintering time is 50 min.

[0070] (2) According to the weight of the components, 10 parts of dry powder calcium fluoride micropowder, 10 parts of graphite, and 10 parts of iron red were weighed and stirred using a stirrer. After stirring for 8 seconds, the mixture was stopped for 20 seconds to wait for cooling to prevent the micropowder and nanopowder from agglomerating. This was repeated for 5 times. Then 70 parts of PTFE emulsion were weighed and stirred using a stirrer. During the stirring process, the dry powder was added and mixed evenly. After continuous stirring for 10 minutes, 30 parts of alcohol was weighed to break the emulsion and form wet 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 drying for 3 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into a crusher for crushing.

[0072] (4) Sprinkle crushed plastic particles on the copper powder plate and compound them through a rolling mill with adjusted size;

[0073] (5) The composite plate is dried in a mesh belt furnace with set temperature and time, the temperature is 250°C, the time is 6 minutes, and then it is continued to pass through a rolling mill with adjusted size. The rolling size thickness is 30 μm larger than the finished product thickness requirement;

[0074] (6) The plate is then placed in a nitrogen-filled box furnace for sintering at a temperature of 370°C for 20 min. After sintering, the plate is rolled into the finished product size through a rolling mill with the size adjusted.

[0075] Comparative Example 5:

[0076] A method for preparing a three-layer composite material for a gear pump, the steps of which are as follows:

[0077] (1) CuSn8Zn3 spherical copper powder is evenly laid on a low-carbon steel plate and sintered to form a copper powder layer with a certain porosity to obtain a copper powder plate. The sintering temperature is 900°C and the sintering time is 50 min.

[0078] (2) According to the weight of the components, 10 parts of dry ETFE micropowder, 5 parts of γ-type nano-alumina, 10 parts of graphite, and 5 parts of iron red were weighed and stirred using a mixer. After every 8 seconds of stirring, the mixture was stopped for 20 seconds to wait for cooling to prevent the micropowder and nanopowder from agglomerating. This was repeated for 5 times. Then 70 parts of PTFE emulsion were weighed and stirred using a mixer. During the stirring process, the dry powder was added and mixed evenly. After continuous stirring for 10 minutes, 30 parts of alcohol was weighed to break the emulsion and form wet 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 drying for 3 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into a crusher for crushing.

[0080] (4) Sprinkle crushed plastic particles on the copper powder plate and compound them through a rolling mill with adjusted size;

[0081] (5) The composite plate is dried in a mesh belt furnace with set temperature and time, the temperature is 250°C, the time is 6 minutes, and then it is continued to pass through a rolling mill with adjusted size. The rolling size thickness is 30 μm larger than the finished product thickness requirement;

[0082] (6) The plate is then placed in a nitrogen-filled box furnace for sintering at a temperature of 370°C for 20 min. After sintering, the plate is rolled into the finished product size through a rolling mill with the size adjusted.

[0083] Comparative Example 6:

[0084] A method for preparing a three-layer composite material for a gear pump, the steps of which are as follows:

[0085] (1) CuSn8Zn3 spherical copper powder is evenly laid on a low-carbon steel plate and sintered to form a copper powder layer with a certain porosity to obtain a copper powder plate. The sintering temperature is 900°C and the sintering time is 50 min.

[0086] (2) According to the weight of the components, 10 parts of dry powder calcium fluoride micropowder, 5 parts of γ-type nano-alumina, 10 parts of graphite, and 5 parts of iron red were weighed and stirred using a mixer. After every 8 seconds of stirring, the mixture was stopped for 20 seconds to wait for cooling to prevent the micropowder and nanopowder from agglomerating. This was repeated for 5 times. Then 70 parts of PTFE emulsion were weighed and stirred using a mixer. During the stirring process, the dry powder was added and mixed evenly. After continuous stirring for 10 minutes, 30 parts of alcohol was weighed to break the emulsion and form wet 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 drying for 3 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into a crusher for crushing.

[0088] (4) Sprinkle crushed plastic particles on the copper powder plate and compound them through a rolling mill with adjusted size;

[0089] (5) The composite plate is dried in a mesh belt furnace with set temperature and time, the temperature is 250°C, the time is 6 minutes, and then it is continued to pass through a rolling mill with adjusted size. The rolling size thickness is 30 μm larger than the finished product thickness requirement;

[0090] (6) The plate is then placed in a nitrogen-filled box furnace for sintering at a temperature of 370°C for 20 min. After sintering, the plate is rolled into the finished product size through a rolling mill with the size adjusted.

[0091] Comparative Example 7:

[0092] A method for preparing a three-layer composite material for a gear pump, the steps of which are as follows:

[0093] (1) CuSn8Zn3 spherical copper powder is evenly laid on a low-carbon steel plate and sintered to form a copper powder layer with a certain porosity to obtain a copper powder plate. The sintering temperature is 900°C and the sintering time is 50 min.

[0094] (2) According to the weight of the components, 10 parts of dry powder calcium fluoride micropowder, 10 parts of ETFE micropowder, 5 parts of graphite, and 5 parts of iron red were weighed and stirred using a mixer. After stirring for 8 seconds, the mixture was stopped for 20 seconds to wait for cooling to prevent the micropowder and nanopowder from agglomerating. This was repeated for 5 times. Then 70 parts of PTFE emulsion were weighed and stirred using a mixer. During the stirring process, the dry powder was added and mixed evenly. After stirring for 10 minutes, 30 parts of alcohol was weighed to break the emulsion and form wet 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 drying for 3 times. When the plastic particles are still moist but no water can be squeezed out, put the plastic particles into a crusher for crushing.

[0096] (4) Sprinkle crushed plastic particles on the copper powder plate and compound them through a rolling mill with adjusted size;

[0097] (5) The composite plate is dried in a mesh belt furnace with set temperature and time, the temperature is 250°C, the time is 6 minutes, and then it is continued to pass through a rolling mill with adjusted size. The rolling size thickness is 30 μm larger than the finished product thickness requirement;

[0098] (6) The plate is then placed in a nitrogen-filled box furnace for sintering at a temperature of 370°C for 20 min. After sintering, the plate is rolled into the finished product size through a rolling mill with the size adjusted.

[0099] Performance Testing and Results

[0100] The performance of the products prepared in the above embodiments and comparative examples was tested, and the testing method was as follows:

[0101] The bonding strength test is carried out according to the method of using a single test column from a single side in GB / T 5210. Before the test, the surface plastic layer is treated with sodium-naphthalene. The diameter of the test column is The speed of the tensile testing machine is 60 mm / min.

[0102] The running time is the durability test, and the test is carried out with reference to the equipment and related parameters in GB / T 7948. The continuous pressure durability test is carried out under the environment of 18MPa / 3000rpm / 80℃;

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

[0104] Table 1 Performance test results of the products prepared in various embodiments and comparative examples

[0105] Material Bonding 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 comparative examples of the same process and different formulations as Example 1, mainly to verify the bonding strength and the running time under the continuous pressure durability test. From Table 1 above, it can be seen that graphite + iron powder has an adverse effect on the bonding strength of the plastic layer. The higher the content, the lower the bonding strength of the plastic layer. As the content of graphite + iron powder decreases, adding ETFE, alumina and calcium fluoride instead has a positive significance for improving the bonding strength. At the same time, the running time under the continuous pressure durability test is gradually improved.

[0107] Obviously, the described embodiments are only some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

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

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

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

4. The method for preparing a three-layer composite material for a gear pump according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) CuSn8Zn3 spherical copper powder is evenly laid on a metal base, and after sintering, a copper powder layer with a certain porosity is formed on the metal base to obtain a copper powder board; (2) weighing 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, and stirring them evenly to obtain a mixed dry powder; adding 65-75 parts of PTFE emulsion to the mixed dry powder and continuing to stir, and then adding alcohol to demulsify the emulsion to form wet plastic particles; (3) heating the wet plastic particles to properly dry them, and when the plastic particles are still moist but no water can be squeezed out, placing the plastic particles in a crusher for crushing; (4) Sprinkling crushed plastic particles on the copper powder plate and compounding through a rolling mill; (5) The composite plate is placed in a mesh belt furnace for drying. After drying, it is rolled through a rolling mill. The rolled size thickness is 20-40 μm larger than the finished product thickness requirement; (6) The plate is sintered in a protective atmosphere and then rolled to the finished size through a rolling mill.

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

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

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

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