Wear-resistant amorphous composite coating and its use in agricultural tool blades

Abstract

The application discloses a wear-resistant amorphous composite coating and application thereof in agricultural tool blades, and belongs to the technical field of composite coatings. The preparation method of the wear-resistant amorphous composite coating comprises the following steps: preparing primary composite powder, pretreatment, first laser cladding, second laser cladding, preparing secondary composite powder and third laser cladding. The preparation of the primary composite powder comprises the following steps: preparing carbon microspheres, compounding, mixing and primary compounding. The preparation of the secondary composite powder comprises the following steps: mixing the primary composite powder and the compounded microspheres, performing ball milling, taking out, and drying to obtain the secondary composite powder. The wear-resistant amorphous composite coating has high hardness, good wear resistance and corrosion resistance, no surface cracks and low porosity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite coating, in particular to a wear-resistant amorphous composite coating and application thereof in agricultural tool blades. BACKGROUND

[0002] With the rapid development of agricultural technology, the agricultural machinery and equipment industry has also ushered in an unprecedented opportunity, and the service performance requirements of agricultural machinery and equipment are becoming more and more demanding. For agricultural tool blades, due to the relatively harsh service conditions of agricultural machinery and equipment, the agricultural tool blades need to be in the harsh environment of atmospheric corrosion, soil corrosion and chemical liquid corrosion for a long time, therefore, wear, corrosion and fatigue fracture become the main factors of failure of agricultural tool blades. Especially the wear of agricultural tool blades, according to statistics, more than 80% of the failure of agricultural tool blades is caused by wear. Because the agricultural tool blades will rub with soil, sand and grass during operation, which leads to a very fast wear rate of the agricultural tool blades, therefore, in the use of agricultural tool blades, passivation, chipping and breaking are prone to occur, which greatly reduces the service life of the agricultural tool blades and affects agricultural production.

[0003] Amorphous substance is considered as the fourth conventional substance state in parallel with gaseous, liquid and solid state, and the amorphous alloy in the amorphous substance refers to the condensed state of liquid atomic disorder arrangement at room temperature or low temperature when the substance is rapidly cooled from liquid or gaseous state due to the lack of crystallization. The atoms in the amorphous alloy are no longer in long-range order, periodicity and regular arrangement, and there is no grain boundary and crystal grain in the amorphous alloy. The amorphous alloy has excellent mechanical and chemical properties, such as extremely high strength and hardness, excellent wear resistance and corrosion resistance, therefore, it has attracted widespread attention of researchers at home and abroad.

[0004] The application discloses a kind of agricultural tool blades, which are coated with amorphous alloy.The amorphous alloy has excellent mechanical and chemical properties, and can improve the wear resistance and corrosion resistance of the agricultural tool blades.The amorphous alloy has poor plastic deformation ability and high brittleness, so the commonly used coating methods include laser cladding, atmospheric plasma spraying, arc spraying, high-velocity oxy-fuel spraying and explosive spraying.The laser cladding method uses a high-energy laser beam emitted by a laser to rapidly heat the surface of the agricultural tool blade, and adds powder to rapidly melt the powder pre-positioned on the surface of the agricultural tool blade or the powder sent synchronously, thereby obtaining an amorphous composite coating with high quality.The laser cladding method has the advantages of small heat-affected zone, metallurgical bonding between the amorphous composite coating and the agricultural tool blade, and low deformation degree of the agricultural tool blade caused by cladding.The amorphous composite coating formed by the laser cladding method contains atomic stacking structure, which can improve the plastic deformation resistance, and contains certain hard particles and nanocrystals.The hard particles are uniformly dispersed in the laser cladding layer, producing dispersion strengthening, and the small grains in the laser cladding layer do not have time to grow into nanocrystals during rapid solidification, and the grain boundaries in the nanocrystals can produce strengthening effect, thereby improving the hardness and wear resistance of the amorphous composite coating.

[0005] The iron-based amorphous alloy is an amorphous alloy formed by adding a small amount of other metal elements to iron.The elements containing iron are melted in liquid form and cooled and formed by rapid cooling technology during preparation.The iron-based amorphous alloy has extremely high hardness, excellent wear resistance and corrosion resistance, low cost, and wide application prospect, so more and more researchers in the field of agricultural machinery and equipment apply the iron-based amorphous alloy to the coating material of agricultural tool blades.

[0006] However, there are the following problems in preparing the iron-based amorphous composite coating by the laser cladding method: first, the laser cladding method is a rapid heating and rapid cooling process, in a short time, the iron-based amorphous alloy and the agricultural tool blade are melted into a liquid state, and then the liquid state is changed into a solid state, in the above process, the iron-based amorphous alloy is constrained by the outside world to generate internal stress, when the internal stress exceeds the yield strength of the iron-based amorphous alloy, cracks will be generated, wherein the internal stress mainly includes thermal stress, microstructure stress and constraint stress, therefore, the iron-based amorphous composite coating prepared by the laser cladding method has the problem of cracks, and also has the problem of high porosity; second, although the iron-based amorphous alloy has strong corrosion resistance, the existence of cracks in the agricultural tool blade coating material will cause crevice corrosion, electrochemical corrosion occurs on the entire surface inside and outside the crack, the anodic reaction is metal ionization, and the cathodic reaction is oxygen reduction, with the continuous occurrence of the corrosion process, the oxygen inside the crack is continuously consumed, and the oxygen outside the crack is supplemented at any time, thereby maintaining the corrosion process, the metal ions inside the crack are continuously accumulated, in order to maintain charge balance, negative ions are enriched inside the crack, thereby causing the inside of the crack to generate soluble metal chlorides due to the concentration of metal ions and the enrichment of chloride ions, the metal chlorides are hydrolyzed to generate insoluble metal hydroxides and free acid, thereby causing the pH inside the crack to decrease, further promoting the dissolution of the anode metal, and causing more chloride ions to migrate from the outside of the crack to the inside of the crack, further promoting the corrosion process, and so on, resulting in the problem of poor corrosion resistance of the iron-based amorphous composite coating prepared by the laser cladding method.

[0007] In view of the above problems, according to the search of existing solutions, the inventors tried the following methods: first, by laser remelting the iron-based amorphous composite coating, the cracks in the iron-based amorphous composite coating are reduced, and the porosity of the iron-based amorphous composite coating is reduced; second, after preparing the laser cladding powder by gas atomization, molybdenum element is added to the laser cladding powder, the molybdenum element and the iron element have a large atomic size, and have a large atomic size difference compared with the boron element and the carbon element, so that the atomic stacking structure is more dense, with the addition of the molybdenum element, it can also provide a large gap, which is beneficial to the embedding of elements with small atomic size, thereby increasing the disordered stacking of alloy liquid phase combination, further causing large structural distortion, and inhibiting the diffusion of atoms, further improving the amorphous forming ability. Moreover, the molybdenum element has the characteristics of self-passivation, and can form a stable passivation film, further, the corrosion resistance of the iron-based amorphous composite coating is improved.

[0008] However, the above method has the following problems: first, laser remelting can increase dislocation density, realize microstructure densification and grain refinement, but after laser remelting, transgranular cracks will appear in the iron-based amorphous composite coating, which will lead to the decrease of wear resistance of the iron-based amorphous composite coating; second, it has been proved by experiments that when the mass fraction of molybdenum element added to the laser cladding powder is greater than 1.5%, the morphology of the middle part of the amorphous composite coating is different from that of the surface layer and the layer close to the substrate, and there are a large number of grains and second phases in the middle part of the amorphous composite coating, which are in the form of wide bands, while there are no obvious grains and second phases in the surface layer and the layer close to the substrate of the amorphous composite coating, and the middle part of the amorphous composite coating is locally enlarged, there are white blocky grains dispersed, superimposed or stacked together, and white punctate phases can also be observed around the white blocky grains, composition analysis shows that the white blocky grains are molybdenum element and iron element, with the increase of the amount of molybdenum element, the white blocky grains are enriched and the grains are increased, and molybdenum-rich dendrites will also appear, which will lead to the decrease of hardness and wear resistance of the iron-based amorphous composite coating, therefore, the mass fraction of molybdenum element added to the laser cladding powder should be controlled within 1.5%, but the smaller the content of molybdenum element, the worse the compactness of the passivation film formed, and the less obvious the effect on improving the corrosion resistance of the iron-based amorphous composite coating. SUMMARY

[0009] In view of the deficiencies in the prior art, the present application provides a wear-resistant amorphous composite coating and its application in agricultural tool blades.

[0010] To solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0011] A wear-resistant amorphous composite coating, the preparation method thereof comprises the following steps: preparing primary composite powder, pretreatment, first laser cladding, second laser cladding, preparing secondary composite powder, and third laser cladding.

[0012] The preparation of the primary composite powder comprises the following steps: preparing carbon microspheres, compounding, mixing, and primary compounding.

[0013] The preparation of the carbon microspheres comprises the following steps: adding sucrose, boric acid and deionized water into a reaction kettle with polytetrafluoroethylene as the inner liner, controlling the stirring speed of the reaction kettle to 40-60 rpm, stirring at room temperature for 20-30 min, sealing the reaction kettle, putting the reaction kettle into an oven, controlling the temperature of the oven to 120-130 DEG C, taking the reaction kettle out of the oven after 10-11 h, naturally cooling to room temperature, transferring the product in the reaction kettle into a centrifuge, controlling the centrifugal speed of the centrifuge to 7000-8000 rpm, centrifuging for 20-25 min, taking the precipitate, washing 4-6 times with deionized water, and vacuum drying at 80-90 DEG C to obtain carbon microspheres.

[0014] The use amount ratio of sucrose, boric acid and deionized water in the preparation of carbon microspheres is 155-165g:6-6.5g:1300-1400mL;

[0015] In the compounding, the carbon microspheres and deionized water are mixed, then added into an ultrasonic oscillator, and ultrasonic oscillation is carried out for 30-40min, sodium molybdate dihydrate is added, and ultrasonic oscillation is continued for 30-40min, sodium borohydride is added into a reaction kettle, the stirring speed of the reaction kettle is controlled to 40-60rpm, and stirring is carried out at room temperature for 50-60min, the product in the reaction kettle is transferred into a centrifuge, the centrifugal speed of the centrifuge is controlled to 7000-8000rpm, and centrifugation is carried out for 20-25min, the precipitate is taken, deionized water is used for washing 4-6times, vacuum drying is carried out at 80-90℃, and the composite microspheres are obtained;

[0016] In the compounding, the use amount ratio of carbon microspheres, deionized water, sodium molybdate dihydrate and sodium borohydride is 40-42g:4000-4500mL:70-80g:60-65g;

[0017] The frequency of the ultrasonic oscillation is 20-25kHz;

[0018] In the mixing, the iron powder, molybdenum powder, chromium powder, boron powder, carbon powder and yttrium powder are uniformly mixed, then added into a vacuum smelting furnace for gas atomization, nitrogen is used as the atomizing gas, the atomization pressure in the gas atomization is controlled to 4-5MPa, and screening is carried out to obtain the laser cladding powder;

[0019] In the mixing, the mass ratio of the iron powder, molybdenum powder, chromium powder, boron powder, carbon powder and yttrium powder is 54-56:17-18:15-15.5:1.2-1.3:3.4-3.6:3.4-3.6;

[0020] The mass purity of the iron powder is 99.99%;

[0021] The mass purity of the molybdenum powder is 99.9%;

[0022] The mass purity of the chromium powder is 99.99%;

[0023] The mass purity of the boron powder is 99.9%;

[0024] The mass purity of the carbon powder is 99.99%;

[0025] The mass purity of the yttrium powder is 99.5%;

[0026] The particle size of the cladding powder is 150-400mesh;

[0027] The primary composite, after mixing the laser cladding powder, molybdenum powder and composite microspheres, is put into a ball mill mixer for ball milling, then taken out and dried in a drying box, and then taken out to obtain the primary composite powder;

[0028] In the primary composite, the mass ratio of the laser cladding powder, the molybdenum powder and the composite microspheres is 100:2.1-2.2:2.1-2.2;

[0029] The mass purity of the molybdenum powder is 99.9%, and the particle size is 300 mesh;

[0030] In the ball milling, the mass ratio of the ball to the material is 2-3:1, the rotation speed is 300-350 rpm, and the ball milling time is 2-2.5 h;

[0031] In the drying, the temperature is 110-120°C, and the drying time is 2-2.5 h;

[0032] In the pretreatment, the surface of the 20# steel plate is polished flat using an angle grinder and a steel wire brush, surface impurities and oxide scales are cleaned, and the steel plate is cleaned with alcohol to obtain a pretreated steel plate;

[0033] In the first laser cladding, the primary composite powder is laid flat on the pretreated steel plate, a pulse laser is used for laser cladding, the surface of the cladding layer is cleaned after laser cladding is completed, and the first laser cladding material is obtained by natural cooling in air;

[0034] In the first laser cladding, the thickness of the laid powder of the primary composite powder is 0.4-0.42 mm;

[0035] In the laser cladding, the laser output power is 600 W, the laser duty cycle is 95%, the focal length is 400 mm, the pulse voltage is 260-300 V, the pulse frequency is 15-20 Hz, the pulse width is 2 ms, and the argon flow rate for spraying the cladding point is 10 L / min;

[0036] In the second laser cladding, the primary composite powder is laid flat on the pretreated steel plate, a pulse laser is used for laser cladding, the surface of the cladding layer is cleaned after laser cladding is completed, and the second laser cladding material is obtained by natural cooling in air;

[0037] In the second laser cladding, the thickness of the laid powder of the primary composite powder is 0.3-0.32 mm;

[0038] In the laser cladding, the laser output power is 600 W, the laser duty cycle is 95%, the focal length is 400 mm, the pulse voltage is 260-300 V, the pulse frequency is 15-20 Hz, the pulse width is 2 ms, and the argon flow rate for spraying the cladding point is 10 L / min;

[0039] The preparation of the secondary composite powder, the primary composite powder and the composite microspheres are mixed, then added into a ball mill mixer for ball milling, then taken out, added into a drying box for drying, then taken out, to obtain the secondary composite powder;

[0040] In the preparation of the secondary composite powder, the mass ratio of the primary composite powder and the composite microspheres is 104.2-104.4:0.9-1;

[0041] In the ball milling, the ball-to-material mass ratio is 2-3:1, the rotation speed is 300-350 rpm, and the ball milling time is 1.5-2 h;

[0042] In the drying, the temperature is 110-120 DEG C, and the drying time is 1.5-2 h;

[0043] In the third laser cladding, the secondary composite powder is laid on the pretreated steel plate, a pulse laser is used for laser cladding, the surface of the cladding layer is cleaned using a steel wire brush after the laser cladding is completed, and the cladding layer is naturally cooled in the air to obtain the wear-resistant amorphous composite coating.

[0044] In the third laser cladding, the thickness of the laid secondary composite powder is 0.4-0.42 mm;

[0045] In the laser cladding, the laser output power is 600 W, the laser duty cycle is 95%, the focal length is 400 mm, the pulse voltage is 260-300 V, the pulse frequency is 15-20 Hz, the pulse width is 2 ms, and the argon flow rate for spraying the cladding point is 10 L / min.

[0046] The application of the foregoing wear-resistant amorphous composite coating in a farm tool blade.

[0047] Compared with the prior art, the application has the following beneficial effects:

[0048] (1) The wear-resistant amorphous composite coating of the present application uses primary composite powder and secondary composite powder in preparation, and molybdenum powder and composite microspheres are added in the preparation of the primary composite powder, wherein the composite microspheres are prepared by first using sucrose and boric acid as raw materials to prepare carbon microspheres, then mixing the carbon microspheres with sodium molybdate dihydrate, loading the sodium molybdate dihydrate on the surface of the carbon microspheres, and then reducing the sodium molybdate dihydrate with sodium borohydride to obtain carbon microspheres loaded with molybdenum elements. After adding molybdenum powder and composite microspheres into the laser cladding powder, the particle size of the composite microspheres is small and can uniformly adhere to the surface of the laser cladding and the molybdenum powder, thereby realizing the uniform dispersion of molybdenum elements and carbon elements. In the process of laser cladding, the molybdenum elements and carbon elements in the composite microspheres can form a more dense atomic stacking structure and realize the pre-embedding of carbon elements, thereby increasing the disordered stacking of alloy liquid phase combination and improving the amorphous forming ability. It can also promote the uniform dispersion of molybdenum powder, avoid the aggregation of white bulk grains formed by molybdenum elements, improve the hardness and wear resistance of the iron-based amorphous composite coating, reduce the porosity, avoid the generation of surface cracks, and also increase the amount of molybdenum elements, improve the corrosion resistance of the iron-based amorphous composite coating, and through three times of laser cladding, increase the amount of composite microspheres in the secondary composite powder used in the three times of laser cladding, i.e. increase the amount of composite microspheres in the surface layer of the amorphous composite coating. The composite microspheres in the surface layer of the amorphous composite coating can play the role of inhibitors, and the carbon in the composite microspheres can combine with the interface of the white bulk grains formed by molybdenum in the middle part of the amorphous composite coating, thereby inhibiting the growth of the white bulk grains, and further improving the hardness and wear resistance of the iron-based amorphous composite coating.

[0049] (2) The wear-resistant amorphous composite coating of the present application has high hardness, and the Vickers hardness is 1231-1272HV 0.3 ;

[0050] (3) The wear-resistant amorphous composite coating of the present application has low porosity, and the porosity is 0.75-0.81%;

[0051] (4) The surface of the wear-resistant amorphous composite coating of the present application is free of cracks;

[0052] (5) The wear-resistant amorphous composite coating of the present application has good wear resistance. The dry sliding friction and wear test is conducted on the wear-resistant amorphous composite coating of the present application, the vertical stress in the dry sliding friction and wear test is controlled to be 100N, tungsten carbide steel ball is used as the counter ball, the hardness of the counter ball is HRA92, the diameter is 9.5mm, the rotation radius is 2mm, the friction time is 60min, and the total sliding distance is 77m, and the weight loss is 0.017-0.021g;

[0053] (6) The wear-resistant amorphous composite coating has good wear resistance, and the self-corrosion current density of the wear-resistant amorphous composite coating is 1.310*10 -5 -1.372*10 -5 A / cm 2 . BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 The SEM analysis diagram of the wear-resistant amorphous composite coating prepared in Example 2;

[0055] Figure 2 The SEM analysis diagram of the wear-resistant amorphous composite coating prepared in Comparative Example 1;

[0056] Figure 3 The SEM analysis diagram of the wear-resistant amorphous composite coating prepared in Comparative Example 2;

[0057] Figure 4 The X-ray diffraction diagram of the wear-resistant amorphous composite coating prepared in Examples 1-3;

[0058] In the figure, the upper curve is the X-ray diffraction diagram of the wear-resistant amorphous composite coating prepared in Example 3, the middle curve is the X-ray diffraction diagram of the wear-resistant amorphous composite coating prepared in Example 2, and the lower curve is the X-ray diffraction diagram of the wear-resistant amorphous composite coating prepared in Example 1. DETAILED DESCRIPTION

[0059] In order to have a clearer understanding of the technical features, objectives and effects of the present application, the specific embodiments of the present application will be described.

[0060] Example 1

[0061] A wear-resistant amorphous composite coating, and a preparation method thereof are provided.

[0062] 1. Preparing a primary composite powder:

[0063] (1) Preparation of carbon microspheres: 155 g of sucrose, 6 g of boric acid, 1300 mL of deionized water are added to a reaction kettle with polytetrafluoroethylene as the inner liner, the stirring speed of the reaction kettle is controlled to 40 rpm, stirring at room temperature for 20 min, the reaction kettle is sealed, the reaction kettle is added to an oven, the temperature of the oven is controlled to 120 DEG C, after 10 h, the reaction kettle is taken out from the oven, and the product in the reaction kettle is transferred into a centrifuge, the centrifugal speed of the centrifuge is controlled to 7000 rpm, centrifugation is performed for 20 min, the precipitate is taken, and the precipitate is washed with deionized water 4 times, vacuum drying at 80 DEG C to obtain carbon microspheres;

[0064] (2) Compound: after 40 g of carbon microspheres and 4000 mL of deionized water are mixed, they are added to an ultrasonic oscillator, the frequency of the ultrasonic oscillator is controlled to 20 kHz, ultrasonic oscillation is performed for 30 min, 70 g of sodium molybdate dihydrate is added, and ultrasonic oscillation is continued for 30 min, 60 g of sodium borohydride is added to a reaction kettle, the stirring speed of the reaction kettle is controlled to 40 rpm, stirring is performed at room temperature for 50 min, the product in the reaction kettle is transferred into a centrifuge, the centrifugal speed of the centrifuge is controlled to 7000 rpm, centrifugation is performed for 20 min, the precipitate is taken, and the precipitate is washed with deionized water 4 times, vacuum drying at 80 DEG C to obtain composite microspheres;

[0065] (3) Mixing: 54 parts of iron powder, 17 parts of molybdenum powder, 15 parts of chromium powder, 1.2 parts of boron powder, 3.4 parts of carbon powder and 3.4 parts of yttrium powder are uniformly mixed and then added to a vacuum melting furnace for gas atomization, nitrogen is used as the atomizing gas, the atomizing pressure in the gas atomization is controlled to 4 MPa, and screening is performed to obtain laser cladding powder;

[0066] The mass purity of the iron powder is 99.99%;

[0067] The mass purity of the molybdenum powder is 99.9%;

[0068] The mass purity of the chromium powder is 99.99%;

[0069] The mass purity of the boron powder is 99.9%;

[0070] The mass purity of the carbon powder is 99.99%;

[0071] The mass purity of the yttrium powder is 99.5%;

[0072] The particle size of the cladding powder is 150 mesh;

[0073] (4) First compounding: 100 parts of laser cladding powder, 2.1 parts of molybdenum powder and 2.1 parts of composite microspheres are mixed by mass fraction, then added into a ball mill mixer, the ball-to-material mass ratio in the ball mill is controlled to 2:1, the rotation speed is controlled to 300 rpm, after 2 hours, taken out, added into a drying oven, the temperature in the drying oven is controlled to 110 DEG C, after 2 hours, taken out, to obtain the first compounded powder;

[0074] The mass purity of the molybdenum powder is 99.9%, and the particle size is 300 mesh;

[0075] 2. Pretreatment: using an angle grinder and a steel wire brush to polish the surface of the 20# steel plate flat, clean the surface impurities and oxide skin, and wipe clean with alcohol, to obtain the pretreated steel plate;

[0076] 3. First laser cladding: the first compounded powder is laid flat on the pretreated steel plate, the powder laying thickness is controlled to 0.4 mm, a pulse laser is used for laser cladding, the laser output power in the laser cladding is controlled to 600 W, the laser duty cycle is 95%, the focal length is 400 mm, the pulse voltage is 260 V, the pulse frequency is 15 Hz, the pulse width is 2 ms, the argon gas flow rate sprayed on the cladding point is 10 L / min, after the laser cladding is completed, the surface of the cladding layer is cleaned with a steel wire brush, and the laser cladding material is obtained by natural cooling in air;

[0077] 4. Second laser cladding: the first compounded powder is laid flat on the pretreated steel plate, the powder laying thickness is controlled to 0.3 mm, a pulse laser is used for laser cladding, the laser output power in the laser cladding is controlled to 600 W, the laser duty cycle is 95%, the focal length is 400 mm, the pulse voltage is 260 V, the pulse frequency is 15 Hz, the pulse width is 2 ms, the argon gas flow rate sprayed on the cladding point is 10 L / min, after the laser cladding is completed, the surface of the cladding layer is cleaned with a steel wire brush, and the second laser cladding material is obtained by natural cooling in air;

[0078] 5. Preparation of second compounded powder: 104.2 parts of first compounded powder and 0.9 parts of composite microspheres are mixed by mass fraction, then added into a ball mill mixer, the ball-to-material mass ratio in the ball mill is controlled to 2:1, the rotation speed is controlled to 300 rpm, after 1.5 hours, taken out, added into a drying oven, the temperature in the drying oven is controlled to 110 DEG C, after 1.5 hours, taken out, to obtain the second compounded powder;

[0079] 6. Three times of laser cladding: spread the secondary composite powder on the pretreated steel plate, control the thickness of the spread powder to be 0.4 mm, use a pulse laser to perform laser cladding, control the laser output power in the laser cladding to be 600 W, the laser duty cycle to be 95%, the focal length to be 400 mm, the pulse voltage to be 260 V, the pulse frequency to be 15 Hz, the pulse width to be 2 ms, the argon gas flow rate sprayed on the cladding point to be 10 L / min, clean the surface of the cladding layer with a steel wire brush after the laser cladding is completed, and naturally cool in the air to obtain the wear-resistant amorphous composite coating.

[0080] The embodiment also provides an application of the aforementioned wear-resistant amorphous composite coating in a farm tool blade.

[0081] Embodiment 2

[0082] A wear-resistant amorphous composite coating, a preparation method thereof is:

[0083] 1. Preparation of the primary composite powder:

[0084] (1) Preparation of carbon microspheres: 160 g of sucrose, 6.2 g of boric acid, and 1350 mL of deionized water were added to a reaction kettle with polytetrafluoroethylene as the inner liner, the stirring speed of the reaction kettle was controlled to 50 rpm, and stirring was performed at room temperature for 25 min. The reaction kettle was sealed, and the reaction kettle was placed in an oven. The temperature of the oven was controlled to 125°C. After 10.5 h, the reaction kettle was taken out of the oven and naturally cooled to room temperature. The product in the reaction kettle was transferred to a centrifuge, the centrifugal speed of the centrifuge was controlled to 8000 rpm, and centrifugation was performed for 20 min. The precipitate was taken and washed with deionized water for 5 times. Vacuum drying was performed at 85°C to obtain carbon microspheres;

[0085] (2) Complexing: 41 g of carbon microspheres and 4200 mL of deionized water were mixed and then added to an ultrasonic oscillator. The frequency of the ultrasonic oscillator was controlled to 20 kHz, and ultrasonic oscillation was performed for 35 min. 75 g of sodium molybdate dihydrate was added, and ultrasonic oscillation was continued for 35 min. 62 g of sodium borohydride was added to the reaction kettle, the stirring speed of the reaction kettle was controlled to 50 rpm, and stirring was performed at room temperature for 55 min. The product in the reaction kettle was transferred to a centrifuge, the centrifugal speed of the centrifuge was controlled to 8000 rpm, and centrifugation was performed for 20 min. The precipitate was taken and washed with deionized water for 5 times. Vacuum drying was performed at 85°C to obtain composite microspheres;

[0086] (3) Mixing: 55 parts of iron powder, 17.5 parts of molybdenum powder, 15.2 parts of chromium powder, 1.2 parts of boron powder, 3.5 parts of carbon powder, and 3.5 parts of yttrium powder were uniformly mixed and then added to a vacuum melting furnace for gas atomization. Nitrogen was used as the atomizing gas. The atomizing pressure in the gas atomization was controlled to 4.5 MPa, and screening was performed to obtain laser cladding powder;

[0087] The mass purity of the iron powder is 99.99%;

[0088] The mass purity of the molybdenum powder is 99.9%;

[0089] The mass purity of the chromium powder is 99.99%;

[0090] The mass purity of the boron powder is 99.9%;

[0091] The mass purity of the carbon powder is 99.99%;

[0092] The mass purity of the yttrium powder is 99.5%;

[0093] The particle size of the cladding powder is 300 mesh;

[0094] (4) First compounding: 100 parts of laser cladding powder, 2.1 parts of molybdenum powder and 2.1 parts of composite microspheres are mixed by mass fraction, and then put into a ball mill mixer for ball milling. The ball-to-material mass ratio in the ball mill is controlled to 2:1, and the rotation speed is controlled to 300 rpm. After 2 hours, it is taken out and dried in a drying box. The temperature in the drying box is controlled to 115 DEG C. After 2 hours, it is taken out to obtain a first compounded powder;

[0095] The mass purity of the molybdenum powder is 99.9%, and the particle size is 300 mesh;

[0096] 2. Pretreatment: use an angle grinder and a steel wire brush to polish the surface of the 20# steel plate flat, clean the surface impurities and oxide skin, and wipe it clean with alcohol to obtain a pretreated steel plate;

[0097] 3. First laser cladding: the first compounded powder is laid flat on the pretreated steel plate, and the thickness of the laid powder is controlled to 0.4 mm. A pulse laser is used for laser cladding, and the laser output power in the laser cladding is controlled to 600 W, the laser duty cycle is 95%, the focal length is 400 mm, the pulse voltage is 300 V, the pulse frequency is 17 Hz, the pulse width is 2 ms, the argon gas flow rate for spraying the cladding point is 10 L / min, and the laser cladding is completed. After the surface of the cladding layer is cleaned with a steel wire brush, it is naturally cooled in air to obtain a first laser cladding material;

[0098] 4. Second laser cladding: the first compounded powder is laid flat on the pretreated steel plate, and the thickness of the laid powder is controlled to 0.3 mm. A pulse laser is used for laser cladding, and the laser output power in the laser cladding is controlled to 600 W, the laser duty cycle is 95%, the focal length is 400 mm, the pulse voltage is 300 V, the pulse frequency is 17 Hz, the pulse width is 2 ms, the argon gas flow rate for spraying the cladding point is 10 L / min, and the laser cladding is completed. After the surface of the cladding layer is cleaned with a steel wire brush, it is naturally cooled in air to obtain a second laser cladding material;

[0099] 5. Preparation of secondary composite powder: 104.2 parts of primary composite powder, 1 part of composite microspheres are mixed, then added to the ball mill mixer for ball milling, the ball-to-material mass ratio in the ball mill is controlled to 2:1, the rotation speed is controlled to 300 rpm, after 2 h, it is taken out and dried in a drying oven, the temperature in the drying oven is controlled to 115°C, after 2 h, it is taken out to obtain the secondary composite powder;

[0100] 6. Third laser cladding: the secondary composite powder is laid flat on the pretreated steel plate, the powder laying thickness is controlled to 0.4 mm, a pulse laser is used for laser cladding, the laser output power in the laser cladding is controlled to 600 W, the laser duty cycle is 95%, the focal length is 400 mm, the pulse voltage is 300 V, the pulse frequency is 17 Hz, the pulse width is 2 ms, the argon gas flow rate for spraying on the cladding point is 10 L / min, after the laser cladding is completed, the surface of the cladding layer is cleaned with a steel wire brush, and the cladding layer is naturally cooled in air to obtain a wear-resistant amorphous composite coating.

[0101] The embodiment also provides an application of the aforementioned wear-resistant amorphous composite coating in a farm tool blade.

[0102] Example 3

[0103] A wear-resistant amorphous composite coating, a preparation method thereof is:

[0104] 1. Preparation of primary composite powder:

[0105] (1) Preparation of carbon microspheres: 165 g of sucrose, 6.5 g of boric acid and 1400 mL of deionized water are added to a reaction kettle with polytetrafluoroethylene as the inner liner, the stirring speed of the reaction kettle is controlled to 60 rpm, stirring at room temperature for 30 min, the reaction kettle is sealed, the reaction kettle is added to an oven, the temperature of the oven is controlled to 130°C, after 11 h, the reaction kettle is taken out from the oven and naturally cooled to room temperature, the product in the reaction kettle is transferred to a centrifuge, the centrifugal speed of the centrifuge is controlled to 8000 rpm, centrifugation is performed for 25 min, the precipitate is taken out, washed with deionized water for 6 times, and vacuum dried at 90°C to obtain carbon microspheres;

[0106] (2) Complexing: 42 g of carbon microspheres and 4500 mL of deionized water are mixed and then added to an ultrasonic oscillator, the frequency of the ultrasonic oscillator is controlled to 25 kHz, ultrasonic oscillation is performed for 40 min, 80 g of sodium molybdate dihydrate is added, ultrasonic oscillation is continued for 40 min, 65 g of sodium borohydride is added to a reaction kettle, the stirring speed of the reaction kettle is controlled to 60 rpm, stirring at room temperature for 60 min, the product in the reaction kettle is transferred to a centrifuge, the centrifugal speed of the centrifuge is controlled to 8000 rpm, centrifugation is performed for 25 min, the precipitate is taken out, washed with deionized water for 6 times, and vacuum dried at 90°C to obtain composite microspheres;

[0107] (3) Mixing: 56 parts of iron powder, 18 parts of molybdenum powder, 15.5 parts of chromium powder, 1.3 parts of boron powder, 3.6 parts of carbon powder, and 3.6 parts of yttrium powder are uniformly mixed, and then added into a vacuum smelting furnace for gas atomization, using nitrogen as the atomizing gas, the atomizing pressure in the gas atomization is controlled to 5 MPa, and screening is performed to obtain a laser cladding powder;

[0108] The mass purity of the iron powder is 99.99%;

[0109] The mass purity of the molybdenum powder is 99.9%;

[0110] The mass purity of the chromium powder is 99.99%;

[0111] The mass purity of the boron powder is 99.9%;

[0112] The mass purity of the carbon powder is 99.99%;

[0113] The mass purity of the yttrium powder is 99.5%;

[0114] The particle size of the cladding powder is 400 mesh;

[0115] (4) First-level compounding: 100 parts of the laser cladding powder, 2.2 parts of molybdenum powder, and 2.2 parts of composite microspheres are mixed, and then added into a ball mill mixer for ball milling, the ball-to-material mass ratio in the ball milling is controlled to 3:1, the rotation speed is controlled to 350 rpm, after 2.5 h, it is taken out, dried in a drying box, the temperature in the drying is controlled to 120°C, after 2.5 h, it is taken out, and a first-level compounding powder is obtained;

[0116] The mass purity of the molybdenum powder is 99.9%, and the particle size is 300 mesh;

[0117] 2. Pretreatment: the surface of a 20# steel plate is polished flat using an angle grinder and a steel wire brush, surface impurities and oxide scales are cleaned, and the steel plate is cleaned with alcohol to obtain a pretreated steel plate;

[0118] 3. First laser cladding: the first-level compounding powder is laid flat on the pretreated steel plate, the thickness of the laid powder is controlled to 0.42 mm, a pulsed laser is used for laser cladding, the laser output power in the laser cladding is controlled to 600 W, the laser duty cycle is 95%, the focal length is 400 mm, the pulse voltage is 300 V, the pulse frequency is 20 Hz, the pulse width is 2 ms, the argon gas flow rate for spraying the cladding point is 10 L / min, the surface of the cladding layer is cleaned using a steel wire brush after the laser cladding is completed, and the first laser cladding material is obtained by natural cooling in air;

[0119] 4. Secondary laser cladding: spread the primary composite powder on the pretreated steel plate, control the powder thickness to be 0.32 mm, use a pulse laser to perform laser cladding, control the laser output power in the laser cladding to be 600 W, the laser duty cycle to be 95%, the focal length to be 400 mm, the pulse voltage to be 300 V, the pulse frequency to be 20 Hz, the pulse width to be 2 ms, the argon flow rate sprayed on the cladding point to be 10 L / min, clean the surface of the cladding layer after laser cladding using a steel wire brush, and naturally cool in the air to obtain a secondary laser cladding material;

[0120] 5. Preparation of secondary composite powder: mix 104.4 parts of primary composite powder and 1 part of composite microspheres by mass fraction, add them into a ball mill mixer, control the ball-to-material mass ratio in the ball mill to be 3:1, and control the rotation speed to be 350 rpm, 2 h later, take out, add into a drying box, control the temperature in the drying to be 120℃, 2 h later, take out, and obtain a secondary composite powder;

[0121] 6. Tertiary laser cladding: spread the secondary composite powder on the pretreated steel plate, control the powder thickness to be 0.42 mm, use a pulse laser to perform laser cladding, control the laser output power in the laser cladding to be 600 W, the laser duty cycle to be 95%, the focal length to be 400 mm, the pulse voltage to be 300 V, the pulse frequency to be 20 Hz, the pulse width to be 2 ms, the argon flow rate sprayed on the cladding point to be 10 L / min, clean the surface of the cladding layer after laser cladding using a steel wire brush, and naturally cool in the air to obtain a wear-resistant amorphous composite coating.

[0122] The embodiment also provides an application of the aforementioned wear-resistant amorphous composite coating in a farm tool blade.

[0123] Comparative Example 1

[0124] On the basis of the preparation method of the wear-resistant amorphous composite coating in Example 2, the step of preparing carbon microspheres in step (1) and the step of compounding in step (2) in the step of preparing primary composite powder in step (1) are omitted, and the step of compounding microspheres in step (4) is omitted; specifically, the step of preparing primary composite powder in step (4) is changed to:

[0125] Mix 100 parts of laser cladding powder and 2.1 parts of molybdenum powder by mass fraction, add them into a ball mill mixer, control the ball-to-material mass ratio in the ball mill to be 2:1, control the rotation speed to be 300 rpm, 2 h later, take out, add into a drying box, control the temperature in the drying to be 115℃, 2 h later, take out, and obtain a primary composite powder;

[0126] The mass purity of the molybdenum powder is 99.9%, and the particle size is 300 mesh;

[0127] Accordingly, the second-stage composite powder is also omitted in Step 5, and the first-stage composite powder is used instead of the second-stage composite powder in the three laser cladding steps in Step 6.

[0128] The remaining technical solutions are consistent with Embodiment 2.

[0129] Comparative Embodiment 2

[0130] On the basis of the preparation method of the wear-resistant amorphous composite coating in Comparative Embodiment 1, the mass fraction range of molybdenum in the first-stage composite powder is changed, and the first-stage composite step in Step (4) is changed to:

[0131] 100 parts of laser cladding powder and 4.2 parts of molybdenum powder are mixed and then added to a ball mill mixer, the mass ratio of balls to materials in the ball mill is controlled to 2:1, the rotation speed is controlled to 300 rpm, and after 2 hours, the mixture is taken out and dried in a drying oven, the temperature in the drying oven is controlled to 115°C, and after 2 hours, the first-stage composite powder is obtained.

[0132] The mass purity of the molybdenum powder is 99.9%, and the particle size is 300 mesh.

[0133] The remaining technical solutions are consistent with Comparative Embodiment 1.

[0134] Performance Test 1

[0135] The Vickers hardness and porosity of the wear-resistant amorphous composite coatings prepared in Embodiments 1-3 and Comparative Embodiments 1-2 are tested, and whether there are cracks on the surface of the wear-resistant amorphous composite coatings is observed, and the test and observation results are as follows:

[0136]

[0137] The wear-resistant amorphous composite coatings prepared in Embodiments 2, Comparative Embodiment 1, and Comparative Embodiment 2 are subjected to SEM analysis. When performing SEM analysis, the cross section of the sample is first treated, specifically, the cross section of the sample is polished, polished, and etched according to the standard for metallographic analysis of samples, i.e., the cross section of the sample is polished in the order of coarse to fine using 600#, 800#, 1000#, and 1200# silicon carbide sandpaper on a sample grinder, then the sample is polished using diamond polishing paste on a polishing machine, and finally the cross section is slightly etched using aqua regia etching solution (the ratio of concentrated hydrochloric acid to concentrated nitric acid is 3:1), and after 5 minutes, the cross section is cleaned and observed under a scanning electron microscope (SEM). The SEM analysis diagram of the wear-resistant amorphous composite coating prepared in Embodiment 2 is shown in Figure 1 , the SEM analysis diagram of the wear-resistant amorphous composite coating prepared in Comparative Embodiment 1 is shown in Figure 2 , and the SEM analysis diagram of the wear-resistant amorphous composite coating prepared in Comparative Embodiment 2 is shown in Figure 3 ;

[0138] By Figures 1-3 It can be seen that the wear-resistant amorphous composite coating prepared in Example 2 is integrally structured and dense, and is well combined with the substrate. The wear-resistant amorphous composite coating prepared in Comparative Example 1 has cracks and white blocky grains, and the wear-resistant amorphous composite coating prepared in Comparative Example 2 also has cracks and white blocky grains, and the white blocky grains are larger due to the increase of the content of molybdenum, which indicates that with the increase of the content of molybdenum, the molybdenum grains are more enriched and the grains are larger.

[0139] Performance test 2

[0140] The wear-resistant amorphous composite coatings prepared in Examples 1-3 were subjected to phase analysis by X-ray diffractometer. Before testing, the samples were treated on a sample grinder using 180# SiC sandpaper to obtain a smooth surface, and then cleaned with alcohol. The diffraction conditions were Cu target, 40KV, 100mA, scanning speed was 8° / min, scanning range 2θ was 10°-90°, and step width was 0.02°. The obtained X-ray diffraction pattern is shown in Figure 4 Figure 4 In the figure, the upper curve is the X-ray diffraction pattern of the wear-resistant amorphous composite coating prepared in Example 3, the middle curve is the X-ray diffraction pattern of the wear-resistant amorphous composite coating prepared in Example 2, and the lower curve is the X-ray diffraction pattern of the wear-resistant amorphous composite coating prepared in Example 1. It can be seen from the figure that the wear-resistant amorphous composite coatings prepared in Examples 1-3 all have a widened diffraction peak at about 43°, and at the same time, there is a sharp crystal peak on the widened diffraction peak, indicating that the wear-resistant amorphous composite coatings prepared in Examples 1-3 contain both amorphous phase and nanocrystalline phase. Figure 4

[0141] Performance test 3

[0142] The wear-resistant amorphous composite coatings prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to dry sliding friction and wear test. The vertical stress in the dry sliding friction and wear test was controlled at 100N, tungsten carbide steel ball was used as the counter ball, the hardness of the counter ball was HRA92, the diameter was 9.5mm, the rotation radius was 2mm, the friction time was 60min, and the total sliding distance was 77m. Then the weight loss of the wear-resistant amorphous composite coating was tested, and the test results are as follows:

[0143]

[0144] Performance test 4

[0145] ​​Corrosion resistance tests were conducted on the wear-resistant amorphous composite coatings prepared in Examples 1-3 and Comparative Examples 1-2, in which a three-electrode system electrochemical workstation was used, a saturated calomel electrode (SCE) was used as a reference electrode, a platinum electrode was used as an auxiliary electrode, and a 1 mol / L hydrochloric acid solution was used as an electrolyte, and the self-corrosion current density of the wear-resistant amorphous composite coatings prepared in Examples 1-3 and Comparative Examples 1-2 was tested at room temperature, and the test results are as follows:

[0146]

[0147] As can be seen from the results of Performance Test 1-4, compared with Comparative Example 1 and Comparative Example 2, the wear-resistant amorphous composite coating prepared in Example 2 has higher hardness, better wear resistance and corrosion resistance, and lower porosity, and no cracks on the surface.

[0148] Unless otherwise specified, the percentages used in the present application are mass percentages.

[0149] Finally, it should be noted that: the above only describes the preferred embodiments of the present application and is not intended to limit the present application, although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or make equivalent replacements to some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A wear-resistant amorphous composite coating, characterized in that, The method for preparing the wear-resistant amorphous composite coating consists of the following steps: preparing primary composite powder, pretreatment, first laser cladding, second laser cladding, preparing secondary composite powder, and third laser cladding; The preparation of the primary composite powder consists of the following steps: preparing carbon microspheres, composite, mixing, and primary composite; To prepare carbon microspheres, sucrose, boric acid, and deionized water are mixed and stirred evenly at room temperature. Under sealed conditions, a hydrothermal reaction is carried out at 120-130°C for 10-11 hours. Then, the mixture is centrifuged, the precipitate is collected, washed, and vacuum dried to obtain carbon microspheres. The composite process involves mixing carbon microspheres and deionized water, ultrasonically vibrating the mixture, adding sodium molybdate dihydrate, continuing ultrasonic vibrating, mixing with sodium borohydride, stirring at room temperature for 50-60 minutes, centrifuging, collecting the precipitate, washing and vacuum drying to obtain the composite microspheres. The mixing process involves uniformly mixing iron powder, molybdenum powder, chromium powder, boron powder, carbon powder, and yttrium powder, then adding the mixture to a vacuum melting furnace for gas atomization. Nitrogen gas is used as the atomizing gas, and the atomization pressure during gas atomization is controlled to 4-5 MPa. The mixture is then sieved to obtain laser cladding powder. The first-stage composite is prepared by mixing laser cladding powder, molybdenum powder, and composite microspheres, followed by ball milling, and then drying to obtain the first-stage composite powder. The first laser cladding process involves spreading primary composite powder evenly on a pretreated steel plate, performing laser cladding using a pulsed laser, cleaning the surface of the cladding layer after laser cladding, and allowing it to cool naturally to obtain the first laser cladding material. The secondary laser cladding involves spreading the primary composite powder evenly on a pretreated steel plate, performing laser cladding using a pulsed laser, cleaning the surface of the cladding layer after laser cladding, and allowing it to cool naturally to obtain the secondary laser cladding material. The preparation of the secondary composite powder involves mixing the primary composite powder and composite microspheres, ball milling them, then removing and drying them to obtain the secondary composite powder. The three-stage laser cladding process involves spreading the secondary composite powder evenly on the pretreated steel plate, performing laser cladding using a pulsed laser, cleaning the surface of the cladding layer after laser cladding, and allowing it to cool naturally in air to obtain a wear-resistant amorphous composite coating.

2. The wear-resistant amorphous composite coating according to claim 1, characterized in that, In the preparation of carbon microspheres, the ratio of sucrose, boric acid, and deionized water is 155-165g: 6-6.5g: 1300-1400mL.

3. The wear-resistant amorphous composite coating according to claim 1, characterized in that, In the composite, the ratio of carbon microspheres, deionized water, sodium molybdate dihydrate, and sodium borohydride is 40-42g:4000-4500mL:70-80g:60-65g. The frequency of the ultrasonic oscillation is 20-25 kHz.

4. The wear-resistant amorphous composite coating according to claim 1, characterized in that, In the mixture, the mass ratio of iron powder, molybdenum powder, chromium powder, boron powder, carbon powder, and yttrium powder is 54-56:17-18:15-15.5:1.2-1.3:3.4-3.6:3.4-3.6; The iron powder has a purity of 99.99%. The molybdenum powder has a purity of 99.9%. The chromium powder has a purity of 99.99%. The boron powder has a purity of 99.9%. The purity of the toner is 99.99%. The yttrium powder has a purity of 99.5%. The particle size of the cladding powder is 150-400 mesh.

5. The wear-resistant amorphous composite coating according to claim 1, characterized in that, In the primary composite, the mass ratio of laser cladding powder, molybdenum powder, and composite microspheres is 100:2.1-2.2:2.1-2.2; The molybdenum powder has a purity of 99.9% and a particle size of 300 mesh. The ball-to-material mass ratio in the ball mill is 2-3:1, the rotation speed is 300-350 rpm, and the ball milling time is 2-2.5 h. The drying temperature is 110-120℃, and the drying time is 2-2.5h.

6. The wear-resistant amorphous composite coating according to claim 1, characterized in that, The pretreatment involves using an angle grinder and a wire brush to smooth the surface of the steel plate, removing surface impurities and oxide scale, and wiping it clean with alcohol to obtain the pretreated steel plate.

7. The wear-resistant amorphous composite coating according to claim 1, characterized in that, In the first laser cladding process, the thickness of the primary composite powder is 0.4-0.42 mm. The laser output power in the laser cladding process is 600W, the laser duty cycle is 95%, the focal length is 400mm, the pulse voltage is 260-300V, the pulse frequency is 15-20Hz, the pulse width is 2ms, and the argon gas flow rate injected to the cladding point is 10L / min.

8. The wear-resistant amorphous composite coating according to claim 1, characterized in that, In the secondary laser cladding, the thickness of the primary composite powder is 0.3-0.32 mm; The laser output power in the laser cladding process is 600W, the laser duty cycle is 95%, the focal length is 400mm, the pulse voltage is 260-300V, the pulse frequency is 15-20Hz, the pulse width is 2ms, and the argon gas flow rate injected to the cladding point is 10L / min. In the preparation of the secondary composite powder, the mass ratio of the primary composite powder to the composite microspheres is 104.2-104.4:0.9-1; The ball-to-material mass ratio in the ball mill is 2-3:1, the rotation speed is 300-350 rpm, and the ball milling time is 1.5-2 hours. The drying temperature is 110-120℃, and the drying time is 1.5-2 hours.

9. The wear-resistant amorphous composite coating according to claim 1, characterized in that, In the three-stage laser cladding process, the thickness of the secondary composite powder is 0.4-0.42 mm. The laser output power in the laser cladding process is 600W, the laser duty cycle is 95%, the focal length is 400mm, the pulse voltage is 260-300V, the pulse frequency is 15-20Hz, the pulse width is 2ms, and the argon gas flow rate injected to the cladding point is 10L / min.

10. The application of the wear-resistant amorphous composite coating according to any one of claims 1-9 in agricultural implement blades.

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