Boron nitride nanosheet enhanced nickel-aluminide intermetallic compound composite coating and preparation method thereof
阅读说明：本技术 一种氮化硼纳米片增强镍三铝金属间化合物复合涂层及其制备方法 (Boron nitride nanosheet enhanced nickel-aluminide intermetallic compound composite coating and preparation method thereof ) 是由 陈瑶 陆小龙 刘卫卫 于 2020-11-20 设计创作，主要内容包括：本发明提供了一种氮化硼纳米片增强Ni-3Al金属间化合物复合涂层的制备方法,包括：将镍粉和铝粉混合,得到混合粉末；将所述混合粉末和氮化硼纳米片分散液混合后干燥,得到粉体；将所述粉体进行喷雾造粒,得到喷涂喂料；将所述喷涂喂料进行等离子喷涂,得到氮化硼纳米片增强Ni-3Al金属间化合物复合涂层。本发明提供了一种兼具轻质、高强韧性和润滑性能的金属间化合物复合涂层的制备方法,获得兼备耐高温、耐磨损、耐腐蚀、低摩擦系数等多种优异性能配合的新型氮化硼纳米片增强Ni-3Al金属间化合物复合涂层。本发明还提供了一种氮化硼纳米片增强Ni-3Al金属间化合物复合涂层。(The invention provides boron nitride nanosheet enhanced Ni 3 The preparation method of the Al intermetallic compound composite coating comprises the following steps: mixing nickel powder and aluminum powder to obtain mixed powder; mixing the mixed powder with the boron nitride nanosheet dispersion liquid, and drying to obtain powder; performing spray granulation on the powder to obtain a spray feed; carrying out plasma spraying on the spraying feed to obtain boron nitride nanosheet enhanced Ni 3 Al intermetallic compound composite coating. The invention provides a preparation method of an intermetallic compound composite coating with light weight, high strength and toughness and lubricating property, and a novel boron nitride nanosheet enhanced Ni with the combination of multiple excellent properties of high temperature resistance, wear resistance, corrosion resistance, low friction coefficient and the like is obtained 3 Al intermetallic compound composite coating. The invention also provides boron nitride nanosheet enhanced Ni 3 Al intermetallic compound composite coating.)
1. Boron nitride nanosheet enhanced Ni3The preparation method of the Al intermetallic compound composite coating comprises the following steps:
mixing nickel powder and aluminum powder to obtain mixed powder;
mixing the mixed powder with the boron nitride nanosheet dispersion liquid, and drying to obtain powder;
performing spray granulation on the powder to obtain a spray feed;
carrying out plasma spraying on the spraying feed to obtain boron nitride nanosheet enhanced Ni3Al intermetallic compound composite coating.
2. The method of claim 1, wherein the method of preparing the mixed powder comprises:
ball-milling nickel powder and aluminum powder by using isopropanol to obtain slurry;
drying and grinding the slurry to obtain mixed powder;
the ball material proportion in the ball milling process is (3-5): 1, the rotating speed is 200-400 r/min, and the ball milling time is 5-7 hours;
the drying temperature is 60-80 ℃.
3. The method according to claim 1, wherein the mass ratio of the nickel powder to the aluminum powder is (80-90): (10-20).
4. The method of claim 1, wherein the method of preparing the boron nitride nanoplate dispersion comprises:
mixing boron nitride nanosheets and isopropanol, and performing ultrasonic dispersion to obtain a boron nitride nanosheet dispersion liquid;
the ultrasonic dispersion time is 3-5 hours.
5. The method of claim 1, wherein the method of mixing the mixed powder and the boron nitride nanoplate dispersion comprises:
putting the mixed powder into the boron nitride nanosheet dispersion liquid for stirring and dispersing;
the rotating speed in the stirring and dispersing process is 4500-5500 rpm, and the stirring and dispersing time is 4-6 hours.
6. The method according to claim 1, wherein the temperature of drying after mixing the mixed powder and the boron nitride nanosheet dispersion is 75-85 ℃.
7. The method according to claim 1, wherein the boron nitride nanosheet is present in the powder in an amount of 0.5 to 1.5% by mass.
8. The method of claim 1, wherein the current during the plasma spraying process is 750-850A, the voltage is 35-45V, the flow rate of the main gas argon is 30-40 slm, and the flow rate of the auxiliary gas helium is 30-40 slm.
9. The method according to claim 1, wherein the distance from the nozzle to the sprayed substrate in the plasma spraying process is 80-100 mm.
10. Boron nitride nanosheet enhanced Ni prepared by the method of claim 13Al intermetallic compound composite coating.
Technical Field
The invention belongs to the technical field of coatings, and particularly relates to boron nitride nanosheet enhanced Ni3An Al intermetallic compound composite coating and a preparation method thereof.
Background
In national important high and new technical equipment such as aerospace, petrochemical metallurgy, energy power, ocean engineering and the like, a large number of key metal friction kinematic pair parts for service safety of equipment in the state of affairs exist, and the parts bear strong friction and abrasion under extreme severe service conditions such as high/low temperature (wide temperature range), high speed, heavy load, oxidation, corrosion and the like, so that the service life of the parts is shortened, and the reliability and the service life of the whole equipment are further influenced. Typically, failure of kinematic pair components begins at their surfaces. Therefore, while the inherent comprehensive properties (toughness, strength and the like) of the base material of the component are maintained, the preparation of the wear-resistant boron nitride nanosheet reinforced Ni3Al intermetallic compound composite coating on the surface of the kinematic pair component by adopting the plasma spraying technology and the preparation method thereof are considered to be an effective method which is economical and feasible and solves the problems.
Ni3Al intermetallic compounds have many excellent properties including high melting point, high resistance to high temperature oxidation, corrosion resistance, high temperature strength and creep resistance and high specific strength, and have positive temperature effects of yield strength below peak temperature, such as Ni3Al has an abnormal yield strength-temperature relation in a temperature range of 600-900 ℃, namely, the strength is increased along with the increase of the temperature. Thus, Ni3The Al intermetallic compound has wide application prospect in civil and military industries as a high-temperature wear-resistant coating. However, Ni3The medium-temperature dynamic brittleness and poor high-temperature creep resistance of Al are main reasons for hindering the practical application and development of engineering. For example, the materials of turbine blades and turbine disks of aero-engines, which are important materials affecting the performance of engines, have very strict requirements on the performance, and not only have good toughness and toughness matching, but also have excellent high-temperature wear resistance. And single Ni3When Al is used as a coating material, the requirement of severe conditions on the surface coating performance of aeroengine parts is often difficult to meet. The results of a number of studies indicate that although Ni is present3Some properties of Al compounds (such as room temperature brittleness, small creep resistance, etc.) can be improved by alloying, but the magnitude of the performance improvement is very limited.
At present, the research direction in the field mainly lies in the development of ceramic fiber/particle (such as TiC, Si)3N4、Al2O3、TiB2Etc.) and this direction is believed to further improve Ni, inter metallic matrix composites (IMCs)3High-temperature mechanical property and high-temperature oxidation resistance of Al. But do notThe density of the ceramic fibers/particles is relatively high, so that the boron nitride nanosheet reinforced Ni is reduced3Specific strength of the Al intermetallic compound composite coating. Patent CN103498074A adopts spark plasma sintering to prepare graphene-reinforced Ni3The result of the Al composite material shows that the tribological performance of the coating is effectively improved by adding the graphene. However, graphene is oxidized at a temperature of 350 ℃ or higher, and the tribological properties of the material at high temperature are reduced.
Disclosure of Invention
In view of the above, the present invention aims to provide a boron nitride nanosheet enhanced Ni3The Al intermetallic compound composite coating and the preparation method thereof have better performance.
The invention provides boron nitride nanosheet enhanced Ni3The preparation method of the Al intermetallic compound composite coating comprises the following steps:
mixing nickel powder and aluminum powder to obtain mixed powder;
mixing the mixed powder with the boron nitride nanosheet dispersion liquid, and drying to obtain powder;
performing spray granulation on the powder to obtain a spray feed;
carrying out plasma spraying on the spraying feed to obtain boron nitride nanosheet enhanced Ni3Al intermetallic compound composite coating.
Preferably, the method for preparing the mixed powder comprises:
ball-milling nickel powder and aluminum powder by using isopropanol to obtain slurry;
drying and grinding the slurry to obtain mixed powder;
the ball material proportion in the ball milling process is (3-5): 1, the rotating speed is 200-400 r/min, and the ball milling time is 5-7 hours;
the drying temperature is 60-80 ℃.
Preferably, the mass ratio of the nickel powder to the aluminum powder is (80-90): (10-20).
Preferably, the preparation method of the boron nitride nanosheet dispersion comprises:
mixing boron nitride nanosheets and isopropanol, and performing ultrasonic dispersion to obtain a boron nitride nanosheet dispersion liquid;
the ultrasonic dispersion time is 3-5 hours.
Preferably, the method for mixing the mixed powder and the boron nitride nanosheet dispersion comprises:
putting the mixed powder into the boron nitride nanosheet dispersion liquid for stirring and dispersing;
the rotating speed in the stirring and dispersing process is 4500-5500 rpm, and the stirring and dispersing time is 4-6 hours.
Preferably, the drying temperature of the mixed powder and the boron nitride nanosheet dispersion liquid after mixing is 75-85 ℃.
Preferably, the mass content of the boron nitride nanosheet in the powder is 0.5-1.5%.
Preferably, the current in the plasma spraying process is 750-850A, the voltage is 35-45V, the flow of the main gas argon is 30-40 slm, and the flow of the auxiliary gas helium is 30-40 slm.
Preferably, the distance between the nozzle and the spraying matrix in the plasma spraying process is 80-100 mm.
The performance of the coating with the laminated structure prepared by plasma spraying is mainly influenced by the morphology, the strength and the crystal structure of the flat particles, the bonding strength among the flat particles and the bonding strength between the flat particles and a matrix. The invention provides boron nitride nanosheet enhanced Ni with light weight, high strength and toughness and lubricating property3The preparation method of the Al intermetallic compound comprises the steps of preparing a spraying feed by adopting a homogenizer to disperse and combine a spray granulation technology, and sintering the obtained powder by utilizing a plasma spraying technology to prepare the boron nitride nanosheet enhanced Ni3Al intermetallic compound composite coating to obtain novel boron nitride nanosheet enhanced Ni with the combination of various excellent performances of high temperature resistance, wear resistance, corrosion resistance, low friction coefficient and the like3Al intermetallic compound composite coating.
The invention provides boron nitride nanosheet enhanced Ni prepared by the method in the technical scheme3Al intermetallic compound composite coating.
The invention provides boron nitride nanosheet enhanced Ni3An Al intermetallic compound composite coating material system adopts Boron Nitride nanosheets (Boron Nitride nanoplatlets, BNNPs) as reinforcements, particularly Ni3High-temperature boron nitride nanosheet enhanced Ni with Al as matrix3An Al intermetallic compound composite coating develops boron nitride nanosheet enhanced Ni with multiple excellent performances of high temperature resistance, wear resistance, corrosion resistance, low friction coefficient and the like by utilizing the characteristics of strong bond combination, high-temperature hardness, special chemical composition and the like of metal aluminide metal bond and covalent bond coexistence, and the characteristics of excellent mechanical properties and the like of boron nitride nanosheets3Al intermetallic compound composite coating material system.
Drawings
FIG. 1 is an SEM image of plasma spray feeds prepared in examples 1-3 of the present invention and comparative example 1, where (a) is comparative example 1, (b) is example 1, (c) is example 2, and (d) is example 3;
FIG. 2 is an SEM photograph of the powder prepared in example 1 of the present invention;
FIG. 3 is an XRD diffraction pattern of the composite coatings prepared in examples 1-3 of the present invention and comparative example 1;
FIG. 4 shows boron nitride nanosheet enhanced Ni prepared in example 1 of the present invention3SEM picture of Al intermetallic compound composite coating section;
FIG. 5 shows the hardness property test results of the composite coatings prepared in examples 1 to 3 of the present invention and comparative example 1;
FIG. 6 shows the results of measuring the friction coefficient of the composite coatings prepared in examples 1 to 3 of the present invention and comparative example 1 (in the figure, the abscissa is the sliding wear distance and the ordinate is the friction coefficient);
FIG. 7 shows the results of the wear rate measurements of the composite coatings prepared in examples 1 to 3 of the present invention and comparative example 1 (the ordinate in the figure is the wear rate).
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other examples, which may be modified or appreciated by those of ordinary skill in the art based on the examples given herein, are intended to be within the scope of the present invention. It should be understood that the embodiments of the present invention are only for illustrating the technical effects of the present invention, and are not intended to limit the scope of the present invention. In the examples, the methods used were all conventional methods unless otherwise specified.
The invention provides boron nitride nanosheet enhanced Ni3The preparation method of the Al intermetallic compound composite coating comprises the following steps:
mixing nickel powder and aluminum powder to obtain mixed powder;
mixing the mixed powder with the boron nitride nanosheet dispersion liquid, and drying to obtain powder;
performing spray granulation on the powder to obtain a spray feed;
carrying out plasma spraying on the spraying feed to obtain boron nitride nanosheet enhanced Ni3Al intermetallic compound composite coating.
In the present invention, the method for preparing the mixed powder preferably includes:
ball-milling nickel powder and aluminum powder by using isopropanol to obtain slurry;
and drying and grinding the slurry to obtain mixed powder.
In the invention, the ball milling equipment is preferably a horizontal planetary ball mill, the ball-material ratio in the ball milling process is preferably (3-5): 1, more preferably 4:1, the rotating speed of the ball mill in the ball milling process is preferably 200-400 r/min, more preferably 250-350 r/min, and most preferably 300r/min, and the ball milling time is preferably 5-7 hours, more preferably 6 hours.
In the invention, the drying temperature is preferably 60-80 ℃, and more preferably 70 ℃.
In the present invention, the particle size of the nickel powder is preferably < 1 μm; the granularity of the aluminum powder is preferably less than 1 mu m; the sources of the nickel powder and the aluminum powder are not particularly limited, and the nickel powder and the aluminum powder which are well known by the technical personnel in the field can be adopted and can be purchased from the market. In the invention, the mass ratio of the nickel powder to the aluminum powder is preferably (80-90): (10-20), more preferably 85: 15.
In the present invention, the method for preparing the boron nitride nanosheet dispersion preferably includes:
and mixing the boron nitride nanosheets and isopropanol, and performing ultrasonic dispersion to obtain a boron nitride nanosheet dispersion liquid.
In the invention, the time of ultrasonic dispersion is preferably 3-5 hours, and more preferably 4 hours.
In the invention, the thickness of the boron nitride nanosheet is preferably less than or equal to 30nm, and the diameter of the boron nitride nanosheet is preferably less than or equal to 5 μm, the source of the boron nitride nanosheet is not particularly limited, and the boron nitride nanosheet is well known to those skilled in the art and can be purchased from the market; the Boron Nitride Nanosheet (BNNP) has a two-dimensional structure, excellent mechanical properties (elastic modulus 700-900 GPa, yield strength-35 GPa), good thermal conductivity 300W/mK and low density (2.1 g/cm)3) And excellent high-temperature stability (the stable structure is still maintained at the temperature of 1000 ℃ below zero in the atmospheric environment), the excellent properties enable the BNNP to become a reinforcing phase with great potential in the wide-temperature-range self-lubricating composite material, the mechanical property of the composite material can be improved, and meanwhile, the composite material has excellent wide-temperature-range self-lubricating property.
In the present invention, the method of mixing the mixed powder and the boron nitride nanosheet dispersion preferably includes:
and (3) putting the mixed powder into the boron nitride nanosheet dispersion liquid for stirring and dispersing.
In the invention, the stirring and dispersing preferably adopts a homogenizer, the rotating speed in the stirring and dispersing process is preferably 4500-5500 rpm, more preferably 5000rpm, and the stirring and dispersing time is preferably 4-6 hours, more preferably 5 hours.
In the invention, the mixed powder and the boron nitride nanosheet dispersion are mixed and then dried preferably in a vacuum drying oven, wherein the drying temperature is preferably 75-85 ℃, and more preferably 80 ℃; after the drying is completed, the obtained dry powder is preferably ground to obtain powder.
In the invention, the mass content of the boron nitride nanosheet in the boron nitride nanosheet dispersion liquid in the powder is preferably 0.5-1.5%, more preferably 0.8-1.2%, and most preferably 1%.
In the invention, the rotating speed of a nozzle in the spray granulation process is preferably 2000-2500 rpm, and more preferably 2100-2200 rpm; the inlet temperature of the nozzle is preferably 260-280 ℃, and more preferably 270 ℃; the outlet temperature of the nozzle is preferably 110-120 ℃. In the present invention, the spray granulation preferably includes:
mixing the powder, polyethylene glycol solution and water to obtain slurry;
and carrying out spray granulation on the slurry to obtain the spray feed.
In the invention, the polyethylene glycol solution is preferably a polyethylene glycol aqueous solution, and the mass concentration of the polyethylene glycol solution is preferably 8-12%; the mass ratio of the powder, the water and the polyethylene glycol solution is preferably (43-47): (9-11).
In the invention, the current in the plasma spraying process is preferably 750-850A, more preferably 780-820A, and most preferably 800A; the voltage is preferably 35-45V, more preferably 38-42V, most preferably 40V, the flow of the primary gas argon is preferably 30-40 slm, more preferably 35slm, the flow of the secondary gas helium is preferably 30-40 slm, more preferably 35slm, and the distance from the nozzle to the sprayed substrate in the plasma spraying process is preferably 80-100 mm, more preferably 85-95 mm, and most preferably 90 mm.
The performance of the coating with the laminated structure prepared by plasma spraying is mainly influenced by the morphology, the strength and the crystal structure of the flat particles, the bonding strength among the flat particles and the bonding strength between the flat particles and a matrix. The invention provides boron nitride nanosheet enhanced Ni with light weight, high strength and toughness and lubricating property3The preparation method of the Al intermetallic compound composite coating comprises the steps of preparing spraying feed by adopting a homogenizer to disperse and combine a spray granulation technology, and sintering the obtained powder by utilizing a plasma spraying technology to prepare the boron nitride nanosheet enhanced Ni3The Al intermetallic compound composite coating has the combination of various excellent performances of high temperature resistance, wear resistance, corrosion resistance, low friction coefficient and the likeNovel boron nitride nanosheet enhanced Ni3Al intermetallic compound composite coating.
The invention provides boron nitride nanosheet enhanced Ni prepared by the method in the technical scheme3Al intermetallic compound composite coating.
The invention provides boron nitride nanosheet enhanced Ni3An Al intermetallic compound composite coating material system adopts Boron Nitride nanosheets (Boron Nitride nanoplatlets, BNNPs) as reinforcements, particularly Ni3High-temperature boron nitride nanosheet enhanced Ni with Al as matrix3The Al intermetallic compound composite coating develops the boron nitride nanosheet enhanced Ni with excellent high-temperature toughness matching and good high-temperature oxidation resistance, particularly high specific strength by utilizing the characteristics of strong bond combination, high-temperature hardness, special chemical components and the like of coexistence of metal aluminide metal bonds and covalent bonds, and the characteristics of excellent physical and chemical properties of boron nitride nanosheets and the like3Al intermetallic compound composite coating material system.
The nickel powder used in the following embodiments of the present invention is provided for last-sea workup new material technology ltd, the aluminum powder is provided for last-sea workup new material technology ltd, and the boron nitride nanosheet is provided for Nanjing Xiancheng nanomaterial technology ltd.
Comparative example 1
Respectively weighing 85 wt.% nickel powder (about 1 μm) and 15 wt.% aluminum powder (about 1 μm) by using an electronic balance;
putting nickel powder and aluminum powder into a horizontal planetary ball mill, adding isopropanol into the mixture for ball milling, wherein the ball material ratio is 4:1 in the ball milling process, the rotating speed of the ball mill is 300r/min, and ball milling is carried out for 6 hours to obtain mixed slurry;
drying the mixed slurry in a vacuum drying oven at 70 ℃, and then grinding into powder to obtain mixed powder;
carrying out spray granulation on the mixed powder to obtain spherical plasma spraying feed;
and (3) carrying out plasma spraying on the plasma spraying feed, wherein the current is 800A, the voltage is 40V, the main gas argon flow is 35slm, the auxiliary gas helium flow is 35slm, and the distance from a plasma spraying nozzle to a spraying matrix is 90mm, so that the composite coating is obtained.
Example 1
Respectively weighing 85 wt.% nickel powder (about 1 μm) and 15 wt.% aluminum powder (about 1 μm) by using an electronic balance;
putting nickel powder and aluminum powder into a horizontal planetary ball mill, adding isopropanol into the mixture for ball milling, wherein the ball material ratio is 4:1 in the ball milling process, the rotating speed of the ball mill is 300r/min, and ball milling is carried out for 6 hours to obtain mixed slurry;
drying the mixed slurry in a vacuum drying oven at 70 ℃, and then grinding into powder to obtain mixed powder;
placing the boron nitride nanosheets in isopropanol for ultrasonic dispersion for 4 hours to obtain boron nitride nanosheet dispersion liquid;
putting the mixed powder into a boron nitride nanosheet dispersion liquid, stirring and dispersing by using a homogenizer at the rotation speed of 5000rpm for 5 hours, drying the obtained mixed liquid in a vacuum drying oven at the temperature of 80 ℃, and then grinding the mixed liquid into powder to obtain powder, wherein the mass content of the boron nitride nanosheets in the powder is 0.5%;
dissolving polyethylene glycol in water, wherein the mass fraction of the polyethylene glycol in the water is 10 wt%, so as to obtain a polyethylene glycol solution; mixing the powder, water and polyethylene glycol solution according to a mass fraction ratio of 45:45:10 to obtain slurry; carrying out spray granulation on the obtained slurry, wherein the rotating speed of a nozzle is 2100rpm, the inlet temperature of the nozzle is 270 ℃, and the outlet temperature of the nozzle is 115 ℃ to obtain spherical plasma spraying feed;
carrying out plasma spraying on the plasma spraying feed, wherein the current is 800A, the voltage is 40V, the flow of main gas and argon is 35slm, the flow of auxiliary gas and helium is 35slm, and the distance from a plasma spraying nozzle to a spraying substrate is 90mm, so that the boron nitride nanosheet enhanced Ni is obtained3Al intermetallic compound composite coating.
Example 2
Respectively weighing 85 wt.% nickel powder (about 1 μm) and 15 wt.% aluminum powder (about 1 μm) by using an electronic balance;
putting nickel powder and aluminum powder into a horizontal planetary ball mill, adding isopropanol into the mixture for ball milling, wherein the ball material ratio is 4:1 in the ball milling process, the rotating speed of the ball mill is 300r/min, and ball milling is carried out for 6 hours to obtain mixed slurry;
drying the mixed slurry in a vacuum drying oven at 70 ℃, and then grinding into powder to obtain mixed powder;
placing the boron nitride nanosheets in isopropanol for ultrasonic dispersion for 4 hours to obtain boron nitride nanosheet dispersion liquid;
putting the mixed powder into a boron nitride nanosheet dispersion liquid, stirring and dispersing by using a homogenizer at the rotation speed of 5000rpm for 5 hours, drying the obtained mixed liquid in a vacuum drying oven at the temperature of 80 ℃, and then grinding the mixed liquid into powder to obtain powder, wherein the mass content of the boron nitride nanosheets in the powder is 1%;
dissolving polyethylene glycol in water, wherein the mass fraction of the polyethylene glycol in the water is 10 wt%, so as to obtain a polyethylene glycol solution; mixing the powder, water and polyethylene glycol solution according to a mass fraction ratio of 45:45:10 to obtain slurry; carrying out spray granulation on the obtained slurry, wherein the rotating speed of a nozzle is 2100rpm, the inlet temperature of the nozzle is 270 ℃, and the outlet temperature of the nozzle is 115 ℃ to obtain spherical plasma spraying feed;
carrying out plasma spraying on the plasma spraying feed, wherein the current is 800A, the voltage is 40V, the flow of main gas and argon is 35slm, the flow of auxiliary gas and helium is 35slm, and the distance from a plasma spraying nozzle to a spraying substrate is 90mm, so that the boron nitride nanosheet enhanced Ni is obtained3Al intermetallic compound composite coating.
Example 3
Respectively weighing 85 wt.% nickel powder (about 1 μm) and 15 wt.% aluminum powder (about 1 μm) by using an electronic balance;
putting nickel powder and aluminum powder into a horizontal planetary ball mill, adding isopropanol into the mixture for ball milling, wherein the ball material ratio is 4:1 in the ball milling process, the rotating speed of the ball mill is 300r/min, and ball milling is carried out for 6 hours to obtain mixed slurry;
drying the mixed slurry in a vacuum drying oven at 70 ℃, and then grinding into powder to obtain mixed powder;
placing the boron nitride nanosheets in isopropanol for ultrasonic dispersion for 4 hours to obtain boron nitride nanosheet dispersion liquid;
putting the mixed powder into a boron nitride nanosheet dispersion liquid, stirring and dispersing by using a homogenizer at the rotation speed of 5000rpm for 5 hours, drying the obtained mixed liquid in a vacuum drying oven at the temperature of 80 ℃, and then grinding the mixed liquid into powder to obtain powder, wherein the mass content of the boron nitride nanosheets in the powder is 1.5%;
dissolving polyethylene glycol in water, wherein the mass fraction of the polyethylene glycol in the water is 10 wt%, so as to obtain a polyethylene glycol solution; mixing the powder, water and polyethylene glycol solution according to a mass fraction ratio of 45:45:10 to obtain slurry; carrying out spray granulation on the obtained slurry, wherein the rotating speed of a nozzle is 2100rpm, the inlet temperature of the nozzle is 270 ℃, and the outlet temperature of the nozzle is 115 ℃ to obtain spherical plasma spraying feed;
carrying out plasma spraying on the plasma spraying feed, wherein the current is 800A, the voltage is 40V, the flow of main gas and argon is 35slm, the flow of auxiliary gas and helium is 35slm, and the distance from a plasma spraying nozzle to a spraying substrate is 90mm, so that the boron nitride nanosheet enhanced Ni is obtained3Al intermetallic compound composite coating.
Performance detection
SEM test of the plasma spray feeds prepared in examples 1-3 of the present invention and comparative example 1 showed that the powder had good sphericity and uniform size distribution as shown in FIG. 1 (in FIG. 1, (a) is comparative example 1, (b) is example 1, (c) is example 2, and (d) is example 3).
SEM examination of the powder prepared in example 1 of the present invention showed that the few-layer boron nitride nanosheets were uniformly dispersed within the powder as shown in fig. 2, which is shown in fig. 2.
XRD (X-ray diffraction) detection is carried out on the composite coatings prepared in the embodiments 1-3 and the comparative example 1, the detection result is shown in figure 3, and as can be seen from figure 3, the boron nitride nanosheet enhanced Ni3The Al intermetallic compound composite coating mainly contains Ni3Al, small amount of Al2O3And NiO.
Ni is enhanced for boron nitride nanosheet prepared in embodiment 1 of the invention3SEM examination of the Al intermetallic compound composite coating cross section shows that the examination result is shown in FIG. 4, and it can be seen from FIG. 4 that the boron nitride layer is fewThe nano-sheets are uniformly dispersed in the coating.
The composite coatings prepared in examples 1 to 3 of the present invention and comparative example 1 were subjected to hardness detection, and measured by a microhardness tester (XD-1000TMC/LCD, shanghai taiming optical instruments ltd.) to obtain coatings with the contents of 0.5 wt.%, 1.0 wt.%, and 1.5 wt.% of boron nitride-free nanosheets and 325HV respectively0.2，358HV0.2，384HV0.2And 417HV0.2As shown in fig. 5, it is understood that the mechanical properties of the coating layer are enhanced with the increase of the number of boron nitride nanosheets.
The friction and wear tests were performed on the composite coatings prepared in examples 1 to 3 of the present invention and comparative example 1, and the friction coefficient and the wear loss of the coating obtained by measuring a friction and wear tester (HT1000, waukee chemical development ltd., kokai, langu) at a load of 20N, a rotation speed of 300rpm, a rotation radius of 2mm, and an alumina ball having a grinding ball diameter of 4mm were shown in fig. 6 and 7, which indicates that the wear resistance and the friction reduction performance of the coating are improved with the increase of boron nitride nanosheets.
The performance of the coating with the laminated structure prepared by plasma spraying is mainly influenced by the morphology, the strength and the crystal structure of the flat particles, the bonding strength among the flat particles and the bonding strength between the flat particles and a matrix. The invention provides boron nitride nanosheet enhanced Ni with light weight, high strength and toughness and lubricating property3The preparation method of the Al intermetallic compound composite coating comprises the steps of preparing spraying feed by adopting a homogenizer to disperse and combine a spray granulation technology, and sintering the obtained powder by utilizing a plasma spraying technology to prepare the boron nitride nanosheet enhanced Ni3Al intermetallic compound composite coating to obtain novel boron nitride nanosheet enhanced Ni with the combination of various excellent performances of high temperature resistance, wear resistance, corrosion resistance, low friction coefficient and the like3Al intermetallic compound composite coating.
The invention provides boron nitride nanosheet enhanced Ni3An Al intermetallic compound composite coating material system adopts Boron Nitride nanosheets (Boron Nitride nanoplatlets, BNNPs) as reinforcements, particularly Ni3High-temperature boron nitride nanosheet reinforced Ni3Al intermetallic compound with Al as matrixThe composite coating develops the boron nitride nanosheet enhanced Ni with the combination of various excellent performances of high temperature resistance, wear resistance, corrosion resistance, low friction coefficient and the like by utilizing the characteristics of strong bond combination, high-temperature hardness, special chemical components and the like of metal aluminide metal bonds and covalent bonds and the characteristics of excellent mechanical properties and the like of the boron nitride nanosheets3Al intermetallic compound composite coating material system.
While only the preferred embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.
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