Nickel-doped cobalt oxide-based nano material and preparation method thereof, and polymer nano composite material and preparation method and application thereof

Abstract

The invention provides a nickel-doped cobalt oxide-based nano material and a preparation method thereof, and a polymer nano composite material and a preparation method and application thereof, and relates to the technical field of lubricating and sealing materials. The preparation method comprises the following steps: mixing oxalic acid, water and soluble metal salts (including cobalt salt and nickel salt) for precipitation reaction, and drying and calcining the obtained precipitate to obtain the nickel-doped cobalt oxide-based nano material. The nano-material is introduced into a polymer material, and in the friction process, alkane and other molecular chain carbon-hydrogen bonds in lubricating oil are activated and subjected to dehydrogenation, carbon chain breakage and carbon-carbon rearrangement reaction by means of the catalytic action of the nano-material; a double-layer structure boundary lubricating film with the upper layer being a highly graphitized carbon-based lubricating layer randomly inlaid with nickel-doped cobalt oxide-based nanocrystals and the lower layer mainly being nickel-doped cobalt oxide-based nanocrystals is generated on the metal dual surface in situ, and the lubricating film has excellent bearing capacity and self-lubricating and self-adaptive self-repairing characteristics; and the polymer nano composite material shows extremely low frictional wear property.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lubricating and sealing materials, and particularly relates to a nickel-doped cobalt oxide-based nanomaterial, a preparation method thereof, and a polymer nanocomposite material, a preparation method thereof and application. BACKGROUND

[0002] With the rapid development of modern industry, the use of friction pair materials in the field of high-end equipment is increasingly demanding. Especially under the condition of repeated start-stop of moving parts, these moving mechanisms are often in a mixed or even boundary lubrication state. For relative moving parts that cannot use external lubricating devices, only fuel (such as diesel, kerosene, etc.) can be used for self-lubrication, such as fuel pumps of engines. As a poor lubricant, mechanical seizure and even lubrication failure often occur under the condition of diesel, kerosene, etc., thereby causing major production safety accidents, which not only brings huge economic losses, but also brings hidden dangers to personal safety. Therefore, the friction and wear of materials is one of the key problems in the design of fuel lubrication system, which will directly affect the normal operation of engines in many fields such as automobiles, and even the safety of the aerospace field.

[0003] Polymer materials, such as polyether ether ketone materials, are gradually applied to a large number of friction systems due to their excellent mechanical properties, corrosion resistance, light weight, self-lubrication and other characteristics. However, when the friction pair is used in a mixed or even boundary lubrication state, due to the presence of fuel medium, on the one hand, the fuel medium will have a "flushing" effect, which will prevent the transfer of polymer materials to the metal counterpart, thereby inhibiting the formation of the transfer film; on the other hand, because of the presence of fuel medium, the heat generated at the friction surface will be absorbed, reducing the interface temperature and affecting the occurrence of the tribochemical reaction, thereby inhibiting the growth of the transfer film; in addition, the fuel medium has low viscosity and poor load capacity, and it is not easy to form a good hydrodynamic lubrication film, so that the traditional self-lubricating polymer materials such as polyether ether ketone are in direct contact with the metal counterpart, causing high wear and affecting the service life of key components such as bearings. Therefore, the traditional polymer materials often exhibit high friction coefficient and large wear under the condition of fuel medium. SUMMARY

[0004] Therefore, the present application aims to provide a nickel-doped cobalt oxide-based nanomaterial, a preparation method thereof, and a polymer nanocomposite material, a preparation method thereof and application. The nickel-doped cobalt oxide-based nanomaterial prepared by the present application is used as a functional nanofiller in polymer materials, and the obtained polymer nanocomposite material exhibits extremely low friction and wear characteristics under oil medium lubrication.

[0005] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0006] The application provides a preparation method of a nickel-doped cobalt oxide-based nanomaterial.

[0007] The oxalic acid, water and soluble metal salt are mixed to perform a precipitation reaction to obtain a precipitate; the soluble metal salt comprises a cobalt salt and a nickel salt, and the molar ratio of the cobalt salt to the nickel salt is (2-5):1;

[0008] The precipitate is sequentially dried and calcined to obtain the nickel-doped cobalt oxide-based nanomaterial.

[0009] Preferably, the soluble metal salt further comprises an aluminum salt and a copper salt, the molar ratio of the aluminum salt, the copper salt and the nickel salt is (0-1):(0-1):1, and the molar amount of the aluminum salt and the copper salt is not 0.

[0010] Preferably, the ratio of the molar amount of the oxalic acid to the total molar amount of the soluble metal salt is (20-50):25.

[0011] Preferably, the calcination temperature is 450-550 DEG C, and the time is 2-5 h.

[0012] The application provides the nickel-doped cobalt oxide-based nanomaterial prepared by the preparation method.

[0013] Preferably, the particle size of the nickel-doped cobalt oxide-based nanomaterial is 20-200 nm.

[0014] The application provides a polymer nanocomposite material, which comprises a polymer matrix material and functional nanofillers compounded in the polymer matrix material, and the functional nanofillers are the nickel-doped cobalt oxide-based nanomaterial.

[0015] Preferably, the mass content of the functional nanofillers in the polymer nanocomposite material is 1-20%.

[0016] The application provides a preparation method of the polymer nanocomposite material, which comprises the following steps:

[0017] The powder of the polymer matrix material is mixed with the functional nanofillers to obtain a premix;

[0018] The premix is hot-pressed to obtain the polymer nanocomposite material.

[0019] The application provides an application of the polymer nanocomposite material or the polymer nanocomposite material prepared by the preparation method in oil lubrication.

[0020] The application provides a preparation method of a nickel-doped cobalt oxide-based nanomaterial, which comprises the following steps: mixing oxalic acid, water and soluble metal salt to perform a precipitation reaction to obtain a precipitate; the soluble metal salt comprises cobalt salt and nickel salt, and the molar ratio of the cobalt salt to the nickel salt is (2-5):1; and the precipitate is sequentially dried and calcined to obtain the nickel-doped cobalt oxide-based nanomaterial.

[0021] The nickel-doped cobalt oxide-based nanomaterial prepared by the application is introduced into a polymer material as a functional nanofiller, and the obtained composite material is rubbed with a metal counterpart in a low-viscosity oil medium; during the rubbing process, the functional nanofiller gradually transfers to the metal counterpart; the nanomaterial attached to the metal counterpart catalytically decomposes to activate and cause dehydrogenation, carbon chain rupture and carbon-carbon rearrangement reactions of molecular chain carbon-hydrogen bonds in alkanes, alkenes and aromatic hydrocarbons in the oil medium, thereby generating an upper highly graphitized carbon-based lubricating layer randomly inlaid with nickel-doped cobalt oxide-based nanocrystals and a lower double-layer boundary lubricating film mainly composed of nickel-doped cobalt oxide-based nanocrystals on the surface of the metal counterpart. The double-layer boundary lubricating film not only has excellent load-carrying capacity and self-lubricating properties, but also has excellent friction catalytic properties due to the nickel-doped cobalt oxide-based nanomaterial with catalytic action, thereby endowing the double-layer boundary lubricating film with excellent self-adaptive self-repairing properties, effectively reducing the friction coefficient and wear rate of the polymer composite material, and increasing the wear resistance of the polymer composite material by 30-90% compared with traditional fiber (such as carbon fiber) and functional nanofiller (such as nano-NiO and Co3O4) modified polymer nanocomposite materials, and significantly improving the service life of the material.

[0022] The application provides a polymer nanocomposite material, which comprises a polymer base material and a functional nanofiller combined in the polymer base material, and the functional nanofiller is the nickel-doped cobalt oxide-based nanomaterial described in the above technical solution. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 Flow chart for preparing nickel-doped cobalt oxide-based nanomaterial and polymer nanocomposite of Example 1 of the present application;

[0024] Figure 2 XRD patterns of NiO, Co3O4 and nickel-doped cobalt oxide NiCoO prepared in Example 1 of the present application; x XRD patterns of NiO, Co3O4 and nickel-doped cobalt oxide NiCoO prepared in Example 1 of the present application;

[0025] Figure 3 XRD patterns of NiO, Co3O4 and nickel-doped cobalt oxide NiCoO prepared in Example 1 of the present application; x SEM images of the three nanomaterials;

[0026] Figure 4 TEM image of the double-layer boundary lubricating film formed during the friction of the polymer nanocomposite prepared in Example 1 of the present application, Figure 4 TEM image of the double-layer boundary lubricating film formed during the friction of the polymer nanocomposite prepared in Example 1 of the present application, DETAILED DESCRIPTION

[0027] The present application provides a method for preparing a nickel-doped cobalt oxide-based nanomaterial, comprising the following steps:

[0028] mixing oxalic acid, water and soluble metal salt to perform a precipitation reaction to obtain a precipitate; the soluble metal salt comprises cobalt salt and nickel salt, and the molar ratio of the cobalt salt to the nickel salt is (2-5):1;

[0029] sequentially drying and calcining the precipitate to obtain the nickel-doped cobalt oxide-based nanomaterial.

[0030] Figure 1 Flow chart for preparing nickel-doped cobalt oxide-based nanomaterial and polymer nanocomposite of Example 1 of the present application, which will be described in detail below. Figure 1

[0031] In the present application, the raw materials involved are all commercially available products unless otherwise specified.

[0032] The present application mixes oxalic acid, water and soluble metal salt to perform a precipitation reaction to obtain a precipitate.

[0033] ​In the present application, the soluble metal salt includes cobalt salt and nickel salt, and the molar ratio of the cobalt salt and the nickel salt is (2-5):1, which can be 2:1, 3:1, 4:1 or 5:1. In the present application, the cobalt salt preferably includes one or more of cobalt acetate, cobalt nitrate and cobalt chloride, and the nickel salt preferably includes one or more of nickel acetate, nickel nitrate and nickel chloride; in the embodiments of the present application, the oxalic acid, cobalt acetate, nickel acetate, aluminum nitrate and copper nitrate are added in the form of oxalic acid dihydrate (C2H2O4·2H2O), cobalt acetate tetrahydrate (Co(CH3COO)2·4H2O), nickel acetate tetrahydrate (Ni(CH3COO)2·4H2O), aluminum nitrate nonahydrate (Al(NO3)3·9H2O) and copper nitrate pentahydrate (Cu(NO3)2·5H2O), respectively.

[0034] In the present application, the soluble metal salt also preferably includes aluminum salt and copper salt, and the molar ratio of the aluminum salt, the copper salt and the nickel salt is preferably (0-1):(0-1):1, and the molar amount of the aluminum salt and the copper salt is not 0 at the same time, and the molar ratio of the aluminum salt, the copper salt and the nickel salt can be 0:1:1 or 1:0:1; the aluminum salt preferably includes one or more of aluminum acetate, aluminum nitrate and aluminum chloride, and the copper salt preferably includes one or more of copper acetate, copper nitrate and copper chloride.

[0035] The present application controls the molar proportion of different metal salts in the soluble metal salt, regulates the molar ratio of different metal elements, and can realize the control of different doping elements and the amount of different doping elements, so as to regulate the structure, morphology, surface active site and catalytic activity of the nickel-doped cobalt oxide-based nanomaterial.

[0036] The application induces the crystal structure distortion of cobalt oxide matrix by different content of nickel doping, and then regulates the geometric structure and electronic state of the active site, the essence of which is to modulate the electronic excitation dynamics and charge carrier mobility inside the nickel-doped cobalt oxide nanomaterial, so as to realize the optimization of its catalytic efficiency. Further introduction of heterogeneous metal elements aluminum or copper constructs a multi-doped system, and through the coordination of strain and defect engineering and electronic structure regulation, the friction catalytic performance of nickel-doped cobalt oxide-based nanomaterial is further optimized. Specifically, the coexistence of different ionic radius dopants (nickel and aluminum or copper) induces the formation of a complex lattice stress / strain field, significantly changes the bond length and bond angle of the crystal, and may trigger local structure phase transition, thereby more efficiently regulating the concentration and spatial distribution of point defects such as oxygen vacancies and cation vacancies. At the same time, the multi-metal ion synergistic effect of the difference in the outer empty orbital of aluminum ion or the electronic configuration of copper ion and the difference in electronegativity between nickel, aluminum or copper realizes the fine modulation of the energy band structure of the material (including the band gap width, the position of the valence band top and the conduction band bottom, and the state density distribution). Finally, this strategy constructs heterogeneous metal active sites with differentiated adsorption energy and reaction path at the atomic scale, and through the synergistic catalytic mechanism of nickel, aluminum or copper multi-metal sites, the friction catalytic performance of nickel-doped cobalt oxide-based nanomaterial for activating the carbon-hydrogen bond of lubricating oil molecules is further optimized, significantly reducing the reaction energy barrier of the rate-determining step of carbon-hydrogen bond breaking and improving the stability of the transition state, thereby comprehensively optimizing the overall friction catalytic activity of nickel-doped cobalt oxide-based nanomaterial.

[0037] In the present application, the ratio of the molar amount of oxalic acid to the total molar amount of soluble metal salt is preferably (20-50):25, which can be 30:25, 36:25 or 45:20.

[0038] In the present application, the water is preferably distilled water. In the present application, the ratio of the amount of water to oxalic acid is (250-500) mL:36 mmol.

[0039] In the present application, the method for mixing oxalic acid, water and soluble metal salt is preferably:

[0040] Dissolve oxalic acid in water to obtain an oxalic acid solution;

[0041] Slowly add the soluble metal salt to the oxalic acid solution.

[0042] In the present application, the precipitation reaction includes stirring reaction and aging in sequence; the time of the stirring reaction is preferably 15-60 min, which can be 30, 40 or 50 min, and the time of the aging is preferably 4-24 h, which can be 5, 10, 12, 15 or 20 h, and the aging is carried out under static conditions. In the present application, the precipitation reaction is carried out at room temperature.

[0043] After the precipitation reaction, a suspension is obtained; the suspension is preferably subjected to solid-liquid separation and solid-phase washing in sequence to obtain the precipitate. In the present application, the solid-liquid separation is preferably performed by centrifugation, and the centrifugation is preferably performed at a speed of 5000-15000 r / min, which can be 7000, 8000, 9000 or 10000 r / min; the washing preferably comprises ethanol washing and deionized water washing in sequence, the ethanol washing is preferably performed for 3-5 times in succession, and the deionized water washing is preferably performed for 3-5 times in succession, both the ethanol washing and the deionized water washing are preferably performed under centrifugation, the centrifugation is preferably performed at a speed of 5000-15000 r / min, which can be 7000, 8000, 9000 or 10000 r / min, and the time for a single washing is preferably 5-15 min, which can be 10 min.

[0044] After obtaining the precipitate, the precipitate is subjected to drying and calcination in sequence to obtain the nickel-doped cobalt oxide-based nanomaterial. In the present application, the drying is preferably performed at a temperature of 60-90℃, which can be 75, 80 or 85℃, and the time is preferably 4-18 h, which can be 12, 15 or 16 h; in the embodiments of the present application, the drying is performed in an oven.

[0045] In the present application, the calcination is preferably performed at a temperature of 450-550℃, which can be 480, 500 or 510℃, and the time is preferably 2-5 h, which can be 2.5, 3 or 4 h, and the calcination is performed in an air atmosphere. The present application preferably places the dried precipitate in an alumina crucible to perform the calcination. In the process of the calcination, the precipitate undergoes a thermal decomposition reaction to form a nickel-doped cobalt oxide-based nanomaterial.

[0046] The present application provides a nickel-doped cobalt oxide-based nanomaterial prepared by the preparation method described in the above technical solution. In the present application, the nickel-doped cobalt oxide-based nanomaterial is represented as NiCoO x When the soluble metal salt further comprises an aluminum salt or a copper salt, the nickel-doped cobalt oxide-based nanomaterial prepared is represented as NiCoAlO x or NiCoCuO x In the present application, the particle size of the nickel-doped cobalt oxide-based nanomaterial is preferably 20-200 nm.

[0047] The present application provides a polymer nanocomposite material, which comprises a polymer matrix material and a functional nanofiller (also referred to as a functional nanoparticle in the embodiments) compounded in the polymer matrix material, and the functional nanofiller is the nickel-doped cobalt oxide-based nanomaterial described in the above technical solution.

[0048] The polymer matrix material has no particular requirements in the present application, and common special engineering polymers such as polyether ether ketone, polyimide or polyphenylene sulfide can be used. The source of the polymer matrix material has no particular requirements in the present application, and commercially available products or preparation methods known to those skilled in the art can be used. In the present application, the mass content of the functional nanofiller in the polymer nanocomposite is preferably 1-20%, which can be 1%, 5%, 10%, 15% or 20%. In the present application, if the mass content of the functional nanofiller in the polymer nanocomposite is less than 1%, the effect of in-situ induction of carbon-based lubricating film by friction catalysis of the composite material is limited, and the carbon-based lubricating film cannot be well formed, and the friction and wear performance is improved less. If the content of the functional nanofiller in the polymer nanocomposite is too high, the mechanical strength of the composite material will be greatly reduced, and there will be a negative impact on the friction and wear performance of the material.

[0049] The present application ingeniously utilizes the catalytic decomposition effect of the functional nanofiller (i.e. the nickel-doped cobalt oxide-based nanomaterial) on alkanes, alkenes and aromatic hydrocarbons in oil medium, and generates a double-layer boundary lubricating film on the surface of the metal counterpart through the transfer of the common special engineering polymer matrix such as polyether ether ketone, polyimide or polyphenylene sulfide and the friction catalysis of the functional nanofiller. The double-layer boundary lubricating film has a highly graphitized carbon-based lubricating layer with a random inlaid nickel-doped cobalt oxide-based nanocrystal on the upper layer and a metal oxide nanocrystal layer (the metal oxide nanocrystal is mainly nickel-doped cobalt oxide-based nanocrystal, and there are also some oxide nanocrystals of the metal counterpart (commonly used materials for engineering equipment such as iron, steel and copper)) on the lower layer. The double-layer boundary lubricating film not only has excellent load-carrying capacity and self-lubricating properties, but also has friction catalysis performance due to the presence of the nickel-doped cobalt oxide-based nanomaterial with catalytic effect, which gives the double-layer boundary lubricating film excellent self-adaptive and self-repairing properties, effectively reduces the friction coefficient and wear rate of the polymer composite material, and significantly improves the service life of the material. The reason why the double-layer boundary lubricating film has self-repairing properties is that the nickel-doped cobalt oxide nanometer particles with friction catalysis effect exist in the boundary lubricating film, and when the carbon-based lubricating film structure is worn or damaged by shear force during friction, the nanometer particles can induce the reformation of the carbon-based material structure and the carbon-carbon rearrangement to form a new carbon-based lubricating film. In addition, the nanometer particles with friction catalysis effect can catalyze the dehydrogenation and carbon rearrangement of lubricating oil molecules to form a carbon-based lubricating film, and can supplement the worn carbon-based lubricating layer in real time, thereby achieving the self-repairing function of the lubricating film and lubrication function.

[0050] The present application provides a preparation method of the polymer nanocomposite as described in the above technical solution, which comprises the following steps:

[0051] Mix the powder of the polymer matrix material with the functional nanofiller to obtain a premix;

[0052] Hot-press the premix to obtain the polymer nanocomposite material.

[0053] The present application mixes the powder of the polymer matrix material with the functional nanofiller to obtain a premix. In the present application, the particle size of the powder of the polymer matrix material is preferably 1-40 μm.

[0054] In the present application, the method of mixing the powder of the polymer matrix material with the functional nanofiller is preferably:

[0055] The functional nanofiller is added to the powder of the polymer matrix material, and high-speed stirring is performed at room temperature to obtain the premix.

[0056] In the present application, the stirring speed is preferably 3000-5000 r / min, which can be 3000, 4000 or 5000 r / min; the stirring is preferably repeated 4-10 times, which can be 8-10 times, and each stirring is preferably continued for 15-60 s, which can be 20-40 s, to achieve the purpose of uniform dispersion.

[0057] After obtaining the premix, the present application hot-presses the premix to obtain the polymer nanocomposite material.

[0058] In the present application, the specific operation of hot-pressing is preferably as follows: the premix is poured into a hot-pressing mold, and the powder in the mold is vibrated and leveled.

[0059] After the premix is loaded, the mold is placed on a hot press for hot-pressing under pressure and temperature.

[0060] In the present application, the process of increasing pressure and temperature needs to be vented; the temperature of hot-pressing is preferably 330-380℃, which can be 330, 340, 350, 375 or 380℃, the pressure is preferably 10-20 MPa, which can be 10, 15 or 20 MPa, and the holding time is 60-120 min, which can be 60, 90, 100, 110 or 120 min. After hot-pressing, the mold is cooled and demolded to obtain the polymer nanocomposite material.

[0061] The application provides application of the polymer nanocomposite material in oil lubrication. The application does not have special requirements for the lubricating oil medium used in the oil lubrication, and common synthetic base oil, mineral oil, plant oil or fuel oil medium can be used, and the embodiment of the application is described by taking aviation kerosene as an example. The functional nanofiller is added into the polymer matrix to obtain the polymer nanocomposite material with low friction coefficient and low wear rate, so that the polymer nanocomposite material can meet the use requirement under the fuel oil lubrication working condition. The polymer nanocomposite material provided by the application has extremely low friction and wear characteristics under the oil lubrication working condition.

[0062] In order to further illustrate the application, the nickel-doped cobalt oxide-based nanomaterial, the preparation method thereof, the polymer nanocomposite material and the preparation method and application thereof are described in detail in combination with examples below, but they should not be understood as limitations to the protection scope of the application.

[0063] Example 1

[0064] A preparation method of a polyether ether ketone composite material (i.e., a polyether ether ketone-based nanocomposite material), the flow is as shown in Figure 1

[0065] (1) Preparation of functional nanoparticles - nickel-doped cobalt oxide-based nanomaterial, the steps are as follows:

[0066] ① 36 mmol of oxalic acid dihydrate (C2H2O4·2H2O) is dissolved in 250 mL of distilled water to obtain an oxalic acid solution;

[0067] ② 20 mmol of cobalt acetate tetrahydrate (Co(CH3COO)2·4H2O) and 10 mmol of nickel acetate tetrahydrate (Ni(CH3COO)2·4H2O) are weighed and slowly added to the oxalic acid solution, stirred for 30 min, and then placed and kept at room temperature for 12 h to obtain a suspension;

[0068] ③ The obtained suspension is centrifuged in a centrifuge tube at a speed of 7000 r / min for 10 min, and the above steps are repeated for 6 times, and the first three times are washed with ethanol, and the last three times are washed with deionized water. The obtained precipitate after centrifugation is dried in an oven at 80℃ for 12 h, and finally the obtained sample is placed in an alumina crucible and calcined at 500℃ in a muffle furnace for 3 h, and the obtained black sample is a nickel-doped cobalt oxide-based nanomaterial.

[0069] (2) Preparation of a polyether ether ketone-based nanocomposite material, the steps are as follows:

[0070] ​Put 5 g of prepared nickel-doped cobalt oxide-based nanomaterial and 95 g of polyether ether ketone powder (Jilin Province Zhongyan High Polymer Material Co., Ltd., PF series-770PF PEEK pure resin fine powder) into a high-speed mixer for mixing, stirring at a speed of 5000 r / min at 25℃ for 30 s, repeating the above steps 10 times to obtain mixed powder, i.e., premix;

[0071] Transfer the premix to a mold and perform hot pressing, keeping the pressure at 10 MPa and the temperature at 375℃ for 120 min, and finally cooling, shaping and demolding to obtain polyether ether ketone-based nanocomposite materials suitable for oil lubrication conditions.

[0072] Example 2

[0073] A method for preparing a polyether ether ketone composite material (i.e., a polyether ether ketone-based nanocomposite material):

[0074] (1) Prepare functional nanoparticles-nickel-copper-doped cobalt oxide-based nanomaterial, steps as follows:

[0075] ①Dissolve 36 mmol of oxalic acid dihydrate (C2H2O4·2H2O) in 350 mL of distilled water to obtain an oxalic acid solution;

[0076] ②Slowly add 15 mmol of cobalt acetate tetrahydrate (Co(CH3COO)2·4H2O), 5 mmol of nickel acetate tetrahydrate (Ni(CH3COO)2·4H2O) and 5 mmol of copper nitrate pentahydrate (Cu(NO3)2·5H2O) to the oxalic acid solution, stir for 30 min, then stand and keep at room temperature for 12 h to obtain a suspension;

[0077] ③Put the obtained suspension into a centrifuge tube and centrifuge at a speed of 10000 r / min for 10 min, repeat the above steps 6 times, the first three times with ethanol washing and the last three times with deionized water washing. Dry the obtained precipitate in an oven at 80℃ for 12 h, and finally place the obtained sample in an alumina crucible and calcine in a muffle furnace at 480℃ for 3.5 h. The obtained black sample is a nickel-copper-doped cobalt oxide-based nanomaterial.

[0078] (2) Prepare polyether ether ketone-based nanocomposite material, steps as follows:

[0079] Put 10 g of prepared nickel-copper-doped cobalt oxide-based nanomaterial and 90 g of polyether ether ketone powder (same as in Example 1) into a high-speed mixer for mixing, stirring at a speed of 5000 r / min at 25℃ for 30 s, repeating the above steps 10 times to obtain mixed powder, i.e., premix;

[0080] The premix is transferred into a mold and hot-pressed under the conditions of a pressure of 15 MPa and a temperature of 375 DEG C for 120 min, and finally cooled, shaped and demolded to obtain a polyether ether ketone-based nanocomposite material suitable for oil lubrication.

[0081] Example 3

[0082] A method for preparing a polyether ether ketone composite material (i.e., a polyether ether ketone-based nanocomposite material):

[0083] (1) Preparation of functional nanoparticles - nickel-aluminum doped cobalt oxide-based nanomaterials, the steps being as follows:

[0084] ① 36 mmol of oxalic acid dihydrate (C2H2O4·2H2O) is dissolved in 400 mL of distilled water to obtain an oxalic acid solution;

[0085] ② 25 mmol of cobalt acetate tetrahydrate (Co(CH3COO)2·4H2O), 5 mmol of nickel acetate tetrahydrate (Ni(CH3COO)2·4H2O) and 5 mmol of aluminum nitrate nonahydrate (Al(NO3)3·9H2O) are slowly added to the oxalic acid solution, stirred for 30 min, and then left to stand at room temperature for 15 h to obtain a suspension;

[0086] ③ The obtained suspension is centrifuged in a centrifuge tube at a speed of 9000 r / min for 10 min, and the above steps are repeated 6 times, with the first three times being washed with ethanol and the last three times being washed with deionized water. The obtained precipitate after centrifugation is dried in an oven at 85 DEG C for 12 h, and finally the obtained sample is placed in an alumina crucible and calcined in a muffle furnace at 510 DEG C for 3 h, and the obtained black sample is a nickel-aluminum doped cobalt oxide-based nanomaterial.

[0087] (2) Preparation of a polyether ether ketone-based nanocomposite material, the steps being as follows:

[0088] 15 g of the prepared nickel-aluminum doped cobalt oxide-based nanomaterial and 85 g of polyether ether ketone powder (the same as in Example 1) are added to a high-speed blender for mixing, stirred at a speed of 5000 r / min at 25 DEG C for 30 s, and the above steps are repeated 10 times to obtain a mixed powder, i.e., a premix;

[0089] The premix is transferred into a mold and hot-pressed under the conditions of a pressure of 10 MPa and a temperature of 340 DEG C for 120 min, and finally cooled, shaped and demolded to obtain a polyether ether ketone-based nanocomposite material suitable for oil lubrication.

[0090] Example 4

[0091] A method for preparing a polyether ether ketone composite material (i.e., a polyether ether ketone-based nanocomposite material):

[0092] (1) Preparation of functional nanoparticles - nickel-doped cobalt oxide-based nanomaterials, the steps are as follows:

[0093] ① 36 mmol of oxalic acid dihydrate (C2H2O4·2H2O) was dissolved in 300 mL of distilled water to obtain an oxalic acid solution;

[0094] ② 15 mmol of cobalt acetate tetrahydrate (Co(CH3COO)2·4H2O) and 5 mmol of nickel acetate tetrahydrate (Ni(CH3COO)2·4H2O) were slowly added to the oxalic acid solution, stirred for 30 min, and then left to stand at room temperature for 15 h to obtain a suspension;

[0095] ③ The obtained suspension was centrifuged in a centrifuge tube at a speed of 8000 r / min for 10 min, and the above steps were repeated 6 times. The first three times were washed with ethanol, and the last three times were washed with deionized water. The precipitate obtained after centrifugation was dried in an oven at 75°C for 15 h, and finally the obtained sample was placed in an alumina crucible and calcined in a muffle furnace at 510°C for 2.5 h. The black sample obtained is a nickel-doped cobalt oxide-based nanomaterial.

[0096] (2) Preparation of polyimide-based nanocomposite, the steps are as follows:

[0097] 10 g of the prepared nickel-doped cobalt oxide-based nanomaterial and 90 g of YS-20 polyimide powder (Shanghai Synthetic Resin Institute, YS-20 molding powder) were added to a high-speed mixer for mixing, and stirred at a speed of 3000 r / min for 40 s at 25°C. The above steps were repeated 8 times to obtain a mixed powder, i.e. a premix;

[0098] The premix was transferred to a mold and hot-pressed at a pressure of 20 MPa and a temperature of 380°C for 90 min, and finally cooled, shaped and demolded to obtain a polyimide-based nanocomposite suitable for oil lubrication conditions.

[0099] Example 5

[0100] A method for preparing a polyphenylene sulfide composite (i.e. a polyphenylene sulfide-based nanocomposite) is provided:

[0101] (1) Preparation of functional nanoparticles - nickel-doped cobalt oxide-based nanomaterials, the steps are as follows:

[0102] ① 36 mmol of oxalic acid dihydrate (C2H2O4·2H2O) was dissolved in 500 mL of distilled water to obtain an oxalic acid solution;

[0103] ② Weigh 25 mmol of cobalt acetate tetrahydrate (Co(CH3COO)2·4H2O), 5 mmol of nickel acetate tetrahydrate (Ni(CH3COO)2·4H2O) and 5 mmol of copper nitrate pentahydrate (Cu(NO3)2·5H2O) and slowly add them to the oxalic acid solution. After stirring for 30 min, let it stand at room temperature for 15 h to obtain a suspension.

[0104] ③ Transfer the obtained suspension into a centrifuge tube and centrifuge at 10,000 r / min for 10 min. Repeat the above steps 6 times, washing with ethanol for the first three times and with deionized water for the last three times. Dry the precipitate obtained after centrifugation in an oven at 75℃ for 16 h. Finally, place the obtained sample in an alumina crucible and calcine it in a muffle furnace at 500℃ for 3 h. The resulting black sample is nickel-copper doped cobalt oxide-based nanomaterial.

[0105] (2) Preparation of polyphenylene sulfide-based nanocomposite materials, the steps are as follows:

[0106] 15g of the prepared nickel-copper doped cobalt oxide-based nanomaterial and 85g of polyphenylene sulfide powder (SUSTEELPPS unreinforced resin produced by Tosoh Corporation of Japan) were added to a high-speed mixer for mixing. The mixture was stirred at 5000r / min for 30s at 25°C. The above steps were repeated 10 times to obtain a mixed powder, i.e., a premix.

[0107] The premixed material was transferred into a mold and hot-pressed. It was kept at 10 MPa and 330°C for 90 minutes. Finally, it was cooled, shaped and demolded to obtain a polyphenylene sulfide-based nanocomposite material suitable for oil lubrication conditions.

[0108] Comparative Example 1

[0109] Preparation method of pure polyetheretherketone material:

[0110] 100g of polyetheretherketone powder (same as in Example 1) was added into a mold and hot-pressed. The mold was kept hot and pressed at 10MPa and 375℃ for 120min. Finally, the mold was cooled, shaped and demolded to obtain pure polyetheretherketone material.

[0111] Comparative Example 2

[0112] Preparation method of polyetheretherketone-based nanocomposites:

[0113] (1) Add 10g NiO and 90g polyether ether ketone powder (same as in Example 1) to a high-speed mixer for mixing. Stir at 5000r / min for 30s at 25°C. Repeat the above steps 10 times to obtain mixed powder, i.e. premix.

[0114] (2) The premixed material is transferred to the mold and hot-pressed. It is kept at 12 MPa and 375 °C for 120 min. Finally, it is cooled, shaped and demolded to obtain polyether ether ketone-based nanocomposite material.

[0115] Comparative Example 3

[0116] Preparation method of polyetheretherketone-based nanocomposites:

[0117] (1) Add 10g of Co3O4 and 90g of polyether ether ketone powder (same as in Example 1) to a high-speed mixer for mixing. Stir at 5000r / min for 30s at 25°C. Repeat the above steps 10 times to obtain a mixed powder, i.e., a premix.

[0118] (2) The premixed material is transferred to the mold and hot-pressed. It is kept at 12 MPa and 375 °C for 120 min. Finally, it is cooled, shaped and demolded to obtain polyether ether ketone-based nanocomposite material.

[0119] Comparative Example 4

[0120] Preparation method of pure polyimide materials:

[0121] 40g of polyimide powder (same as in Example 4) was added into the mold and hot-pressed. The mold was kept at 15MPa and 380℃ for 90 minutes. Finally, the mold was cooled, shaped and demolded to obtain pure polyimide material.

[0122] Comparative Example 5

[0123] Preparation method of pure polyphenylene sulfide material:

[0124] 40g of polyphenylene sulfide powder (same as in Example 5) was added into the mold and hot-pressed. The mold was kept hot and pressed at 10MPa and 330℃ for 90 minutes. Finally, the mold was cooled, shaped and demolded to obtain pure polyphenylene sulfide material.

[0125] Figure 2 For NiO, Co3O4 and nickel-doped cobalt oxide NiCoO prepared in Example 1 x X-ray diffraction (XRD) patterns of three nanomaterials (Ni1Co2O4). Figure 2 It can be seen that the overall structure of Ni1Co2O4 in the X-ray diffraction pattern is consistent with the typical crystal structure of Co3O4, but small NiO characteristic peaks appear, and the shift of the characteristic peak of the (311) crystal plane means that lattice distortion has occurred, indicating that nickel element has been successfully doped into the lattice of cobalt oxide.

[0126] Figure 3 For NiO, Co3O4 and nickel-doped cobalt oxide NiCoO prepared in Example 1 xThe scanning electron microscope topography of the three nanomaterials, and the particle size of the three nanomaterials is 20-200 nm.

[0127] Comparative Example 6

[0128] Method for preparing polyether ether ketone-based short carbon fiber composite material:

[0129] (1) 10 g of SCF (short carbon fiber) and 90 g of polyether ether ketone powder (the same as in Example 1) were added into a high-speed mixer for mixing, and stirring was carried out at a speed of 5000 r / min at 25℃ for 30 s, and the above step was repeated for 10 times to obtain a mixed powder, i.e. a premix;

[0130] (2) The premix was transferred into a mold and hot-pressed, and the pressure was kept at 15 MPa and the temperature was kept at 375℃ for 120 min, and finally cooled, shaped and demolded to obtain a polyether ether ketone-based nanocomposite material.

[0131] Friction experiment

[0132] The sample hot-pressed in the example and comparative example was processed into a test block with a size of 25 mm x 10 mm x 5 mm, and tribological experiment was carried out on a standard high-speed ring block friction tester (MRH-1A, Jinan Yihua), and the friction and wear performance analysis of each test sample was repeated at least three times. Test conditions: metal counter steel ring (GCr15, GB / T 18254-2002), initial surface roughness Ra = 0.1-0.15 μm, experimental load 100 N, sliding linear velocity 0.2 m / s, friction and wear experimental time 120 min, lubricating medium: aviation kerosene RP-3, oil supply amount: 6-8 μL / min. After the friction test, the wear scar width was measured by optical microscope, and the wear rate was calculated by formula, and the volume wear rate calculation formula is as follows:

[0133]

[0134] In the formula, L' and W are the length and width of the wear scar (mm), F is the applied load (N), L is the total sliding distance (m), and R is the radius of the steel ring (25 mm).

[0135] The test results of the friction experiment are shown in Table 1.

[0136] Table 1 Average friction coefficient and volume wear rate of the polymer composite material prepared in the example and comparative example

[0137] Friction coefficient wear rate (10 -7 mm 3 / Nm)]]> Example 1 0.128 4.48 Example 2 0.118 3.15 Example 3 0.111 2.71 Example 4 0.121 3.17 Example 5 0.089 2.09 Comparative Example 1 0.158 11.98 Comparative Example 2 0.145 6.14 Comparative Example 3 0.136 5.70 Comparative Example 4 0.171 28.34 Comparative Example 5 0.121 7.83 Comparative Example 6 0.151 6.25

[0138] As can be seen from Table 1, compared with the comparative example, the polyether ether ketone-based, polyimide-based and polyphenylene sulfide-based nanocomposite materials prepared in the application have significant friction-reducing and wear-resistant properties.

[0139] Figure 4 The TEM images of the boundary lubrication film formed by the polymer nanocomposite prepared in Example 1 during the friction process, Figure 4 (a) is the TEM image of the boundary lubrication film with double-layer structure, (b) and (c) are the TEM images of the graphitized carbon-based lubrication film. The Figure 4 It can be clearly seen that the above polymer nanocomposite forms a relatively uniform boundary lubrication film with double-layer structure on the surface of the metal pair during the friction process, as shown in Figure 4 (a), and there is a highly graphitized carbon in the area of the upper carbon-based lubrication film, as shown by the formation of Figure 4 the nanographite structure in (b) and Figure 4 the onion-like nanocarbon structure in (c), indicating that the nickel-doped cobalt oxide-based nanomaterial induces the in-situ formation of the highly graphitized carbon-based lubrication film during the friction process through its friction catalysis effect. The formation of this carbon-based lubrication film effectively reduces the friction coefficient and wear rate of the material, with a maximum reduction of 90%. Therefore, the nickel-doped cobalt oxide-based nanomaterial as a functional nanofiller can effectively enhance the tribological properties of the polymer material.

[0140] The above only describes the preferred embodiments of the present application, and does not limit the present application in any form. It should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing nickel-doped cobalt oxide-based nanomaterials, characterized in that, Includes the following steps: Oxalic acid, water, and a soluble metal salt are mixed and subjected to a precipitation reaction to obtain a precipitate; the soluble metal salt includes cobalt salt and nickel salt, and the molar ratio of the cobalt salt to the nickel salt is (2-5):1; The precipitate was dried and calcined sequentially to obtain the nickel-doped cobalt oxide-based nanomaterial.

2. The preparation method according to claim 1, characterized in that, The soluble metal salt also includes aluminum salt and copper salt, wherein the molar ratio of aluminum salt, copper salt and nickel salt is (0-1):(0-1):1, and the molar amounts of aluminum salt and copper salt are not both 0.

3. The preparation method according to claim 1 or 2, characterized in that, The molar ratio of oxalic acid to the total molar ratio of soluble metal salt is (20-50):

25.

4. The preparation method according to claim 1, characterized in that, The calcination temperature is 450–550℃, and the time is 2–5 hours.

5. Nickel-doped cobalt oxide-based nanomaterials prepared by the preparation method according to any one of claims 1 to 4.

6. The nickel-doped cobalt oxide-based nanomaterial according to claim 5, characterized in that, The particle size of the nickel-doped cobalt oxide-based nanomaterial is 20–200 nm.

7. A polymer nanocomposite material, characterized in that, It includes a polymer matrix material and a functional nanofiller incorporated in the polymer matrix material, wherein the functional nanofiller is the nickel-doped cobalt oxide-based nanomaterial as described in claim 5 or 6.

8. The polymer nanocomposite material according to claim 7, characterized in that, The functional nanofiller content in the polymer nanocomposite material is 1-20% by mass.

9. The method for preparing the polymer nanocomposite material according to claim 7 or 8, characterized in that, Includes the following steps: The polymer matrix material powder is mixed with the functional nanofiller to obtain a premix; The premixed material is hot-pressed to obtain the polymer nanocomposite material.

10. The application of the polymer nanocomposite material according to claim 7 or 8 or the polymer nanocomposite material prepared by the preparation method according to claim 9 in oil lubrication.

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