CN114990541B - High-hardness material coating structure and preparation method thereof - Google Patents

High-hardness material coating structure and preparation method thereof Download PDF

Info

Publication number
CN114990541B
CN114990541B CN202210605175.XA CN202210605175A CN114990541B CN 114990541 B CN114990541 B CN 114990541B CN 202210605175 A CN202210605175 A CN 202210605175A CN 114990541 B CN114990541 B CN 114990541B
Authority
CN
China
Prior art keywords
hardness material
powder
coating
amorphous alloy
transition layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202210605175.XA
Other languages
Chinese (zh)
Other versions
CN114990541A (en
Inventor
单光存
张吉亮
石灿鸿
李鑫
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Beihang University
Original Assignee
Beihang University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Beihang University filed Critical Beihang University
Priority to CN202210605175.XA priority Critical patent/CN114990541B/en
Publication of CN114990541A publication Critical patent/CN114990541A/en
Application granted granted Critical
Publication of CN114990541B publication Critical patent/CN114990541B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C24/00—Coating starting from inorganic powder
    • C23C24/02—Coating starting from inorganic powder by application of pressure only
    • C23C24/04—Impact or kinetic deposition of particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/06—Metallic powder characterised by the shape of the particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/06—Metallic powder characterised by the shape of the particles
    • B22F1/065—Spherical particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/14—Treatment of metallic powder
    • B22F1/142—Thermal or thermo-mechanical treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/14—Treatment of metallic powder
    • B22F1/145—Chemical treatment, e.g. passivation or decarburisation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
    • B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
    • B22F9/082—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/14—Making metallic powder or suspensions thereof using physical processes using electric discharge
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
    • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
    • C22C29/06—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds
    • C22C29/08—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds based on tungsten carbide

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Metallurgy (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Nanotechnology (AREA)
  • Organic Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Coating By Spraying Or Casting (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)

Abstract

A high-hardness material coating structure and a preparation method thereof are provided, wherein the high-hardness material coating structure comprises: using an amorphous alloy as a substrate or a transition layer; and spraying high-hardness material powder on the amorphous alloy substrate or the transition layer by adopting a cold spraying process, and obtaining a high-hardness material compact coating on the amorphous alloy substrate or the transition layer. The amorphous alloy allows larger local shearing deformation, high-hardness material powder is impacted on an amorphous alloy substrate or a transition layer at a speed exceeding a critical deposition speed in a cold spraying process, the impact process causes large shearing deformation and shearing softening of an amorphous surface, and the low temperature of cold spraying can not cause amorphous crystallization, so that the bonding strength between the amorphous alloy substrate or the transition layer and sprayed particles is effectively enhanced, the falling of the particles is obviously inhibited, and a compact and high-hardness coating can be prepared.

Description

High-hardness material coating structure and preparation method thereof
The present application is a divisional application of Chinese patent application (application day: 2020, 6, 30 days; title of invention: coating structure of high hardness material) with application number 202010616217.0.
Technical Field
The present disclosure relates to a coating structure of high hardness material and a preparation method thereof, which belongs to the technical field of alloy material and surface cold spraying.
Background
The cold spraying technology is a low-temperature spraying technology which takes preheated compressed gas (nitrogen, ammonia, air or mixed gas) as an accelerating medium, drives metal particles to impact a workpiece substrate at a very high speed in a solid state, and deposits the metal particles on the surface of the substrate in a mode of strong plastic deformation of the particles to form a coating. Cold spraying differs most from thermal spraying in that the extent to which particles are heated differs from the state before they strike the surface of the workpiece. The three major heat-flow temperatures of the traditional thermal spraying technology are respectively as follows: combustion flames, the temperature of which is higher than 2000 ℃; arc, the temperature reaches more than 5000 ℃; the temperature of the plasma, e.g., palladium plasma, is as high as 16000 ℃, so that thermally sprayed particles melt during deposition and accompany the metallurgical processes of droplet impingement, welding, cooling, solidification, phase transformation, etc., while cold sprayed particles do not melt during deposition, and solid particles undergo adiabatic shear destabilization under extremely high strain and strain rate conditions, thereby causing plastic rheology and forming mechanical bite.
A critical deposition rate exists during the deposition of the cold sprayed particles, and only when the flight speed of the particles exceeds the critical deposition rate, the erosion of the substrate by the particles is converted to a perforating effect to deposit the coating. Generally, the higher the hardness of the particles, the higher the critical deposition rate, i.e., the higher the hardness of the powder particles, the more difficult it is to deposit, and therefore, the higher hardness alloy is not suitable for effectively depositing a coating using cold spray techniques. The low-hardness pure metal or alloy can be used for preparing the coating by using a cold spraying technology, but the wear resistance of the coating often cannot meet the use requirements. Since cold spray techniques rely on high pressure air streams to cause the velocity of the particles to exceed the critical deposition velocity to achieve a coating, increasing the velocity of the particles is critical for the production of high performance coatings. The flight speed of the particles is mainly related to the carrier gas and the carrier gas preheating temperature. The acceleration effect of ammonia in common carrier gas is optimal, but the cost is too high; nitrogen is most economical but has poor acceleration. The preheating temperature of the carrier gas is mainly used for enhancing the expansion effect of gas molecules in the contraction section of the nozzle, so that the maximum flow speed of the air flow in the expansion section is achieved, but the improvement of the preheating temperature of the carrier gas is limited by deposition materials and equipment, the equipment is upgraded, the nozzle structure is improved, the technological parameters are optimized, a single cold spraying technology still cannot be used for depositing and preparing alloy material coatings with higher hardness, and the popularization of the spraying technology is greatly restricted.
Most of the research at present mainly improves the deposition effect of the high-hardness alloy material coating by adjusting the process parameters of cold spraying, such as the preheating temperature of the carrier gas and the pressure of the carrier gas. Some researches are carried out on the prepared spherical powder repeatedly impacting on a substrate with surface protrusions of corresponding specifications at high speed, so that pits are formed on the surface of the metal powder, the occurrence of flow separation is restrained by improving the surface morphology of the powder, the flying speed of the powder in the spraying process is improved, and the effect of improving the compactness of the coating is achieved.
There is therefore a need for a method that can produce dense coatings of high hardness alloys.
Disclosure of Invention
First, the technical problem to be solved
The present disclosure provides a coating structure of a high hardness material and a method for preparing the same, to at least partially solve the technical problems set forth above.
(II) technical scheme
According to one aspect of the present disclosure, there is provided a method of preparing a coating structure of a high hardness material, comprising: using an amorphous alloy as a substrate or a transition layer; and spraying high-hardness material powder on the amorphous alloy substrate or the transition layer by adopting a cold spraying process, and obtaining a high-hardness material compact coating on the amorphous alloy substrate or the transition layer.
In one embodiment of the present disclosure, the amorphous alloy is metallic glass.
In one embodiment of the present disclosure, the high hardness material powder is a tungsten carbide alloy powder, wherein the mass ratio of tungsten to carbon is 10:1, and the purity of the tungsten carbide alloy powder is greater than 99.9%;
the characteristic size of the powder particles of the high-hardness material powder is 0.7-2 mu m;
the size of the particles in the high-hardness material coating is 1-5 mu m.
In an embodiment of the disclosure, the tungsten carbide alloy powder has a carbon content of 6.1% -6.18%, a content of elemental carbon impurities of less than 0.05%, a mass percentage of Fe of 0.01% -0.02%, and a mass percentage of Mo of less than 0.01%.
In one embodiment of the present disclosure, the spraying of the high hardness material powder on the amorphous alloy substrate or the transition layer using a cold spray process includes: feeding the high-hardness material powder into a powder feeder or a converging-diverging spray gun for spraying;
wherein, nitrogen or compressed air is used as spraying gas, and the air pressure is 100-200 atmospheres; the pressure of the powder feeder is set to be 50 atmospheres greater than the pressure of the main gas stream including the spray gas carrying the high hardness material powder;
preferably, the air pressure of the compressed air is 15 atmospheres or more.
In an embodiment of the disclosure, the high hardness material powder is a tungsten carbide alloy powder, and the preparation method of the tungsten carbide alloy powder includes: putting raw materials of carbon and tungsten into a vacuum induction furnace according to preset components for smelting, respectively carrying out deslagging, refining, homogenizing and atomizing treatment, and drying and sieving to obtain a tungsten carbide alloy powder crude product; carrying out solution treatment on the tungsten carbide alloy powder crude product, and then carrying out water quenching to room temperature; and (3) carrying out hydrogen reduction on the crude tungsten carbide alloy powder after water quenching to obtain the tungsten carbide alloy powder.
In one embodiment of the disclosure, the smelting temperature is 1400 ℃ to 1550 ℃; and/or the number of the groups of groups,
the temperature of hydrogen reduction is 200-300 ℃, and the reduction time is 1-3 h; and/or the number of the groups of groups,
the temperature of the solid solution treatment is 1050-1100 ℃; the heat preservation time is lh-2 h.
In an embodiment of the disclosure, the method of atomization treatment is a vacuum gas atomization method or a plasma rotating electrode method.
In one embodiment of the present disclosure, the crude tungsten carbide alloy powder is spherical or spheroidic, with a particle size of less than 5 μm.
In one embodiment of the present disclosure, the hardness of the tungsten carbide alloy powder is 170-200.
In an embodiment of the present disclosure, the tungsten carbide alloy powder is spherical, near-spherical, or polygonal in shape.
According to another aspect of the present disclosure, there is provided a high hardness material coating structure including: an amorphous alloy substrate or transition layer; and a coating of a high hardness material formed on the amorphous alloy substrate or the transition layer.
In one embodiment of the present disclosure, a dense coating of high hardness material is formed by spraying a powder of the high hardness material on an amorphous alloy substrate or a transition layer using a cold spray process;
optionally, the amorphous alloy is a nanocrystalline alloy or metallic glass;
optionally, the high hardness material powder is tungsten carbide alloy powder, wherein the mass ratio of tungsten to carbon is 10:1, the purity of the tungsten carbide alloy powder is more than 99.9 percent;
optionally, in the tungsten carbide alloy powder, the carbon content is 6.1% -6.18%, the content of simple substance carbon impurities is less than 0.05%, the mass percentage of Fe is 0.01% -0.02%, and the mass percentage of Mo is less than 0.01%;
optionally, the hardness of the tungsten carbide alloy powder is 170-200;
optionally, the tungsten carbide alloy powder is spherical, near-spherical or polygonal in shape.
(III) beneficial effects
According to the technical scheme, the high-hardness material coating structure and the preparation method thereof have the following beneficial effects:
the amorphous alloy is used as a substrate or a transition layer, the amorphous alloy substrate or the transition layer is sprayed with high-hardness material powder by adopting a cold spraying process, and the amorphous alloy allows larger local shearing deformation, the high-hardness material powder is impacted on the amorphous alloy substrate or the transition layer at a speed exceeding the critical deposition speed in the cold spraying process, the impact process causes large shearing deformation and shearing softening of the amorphous surface, and the low temperature of the cold spraying can not cause amorphous crystallization, so that the bonding strength between the amorphous alloy substrate or the transition layer and sprayed particles is effectively enhanced, the falling of the particles is obviously inhibited, and a compact and high-hardness coating can be prepared.
Drawings
Fig. 1 is a schematic diagram of a method for preparing a coating of a high hardness material according to an embodiment of the present disclosure.
Fig. 2 is a flow chart of a method of preparing a coating of a high hardness material according to an embodiment of the present disclosure.
Fig. 3 is a surface morphology SEM image of a high hardness material coating prepared by the preparation method of the high hardness material coating according to an embodiment of the present disclosure.
FIG. 4 is a graph of gas velocity in a lance versus axial position according to an embodiment of the disclosure.
FIG. 5 is a graph of axial velocity of particles versus particle size according to an embodiment of the present disclosure.
Fig. 6 is a schematic photograph of a sample of a coating of a high hardness material according to an embodiment of the present disclosure, wherein (a) is a photograph of sample a, (B) is a photograph of sample B, (C) is a photograph of sample C, and (D) is a photograph of sample D.
Fig. 7 is a surface morphology SEM spectrum of the high hardness material coating sample shown in fig. 6, wherein (a) is a SEM spectrum of sample a, (B) is a SEM spectrum of sample B, (C) is a SEM spectrum of sample C, and (D) is a SEM spectrum of sample D.
FIG. 8 shows the microstructure of the coating sample of the high hardness material shown in FIG. 6 in secondary electron mode, (a 1) is the microstructure of sample A; (a 2) is the microstructure of sample a at higher magnification; (B1) is the microstructure of sample B; (B2) is the microstructure of sample B at higher magnification; (C1) is the microstructure of sample C; (C2) is the microstructure of sample C at higher magnification; (D1) is the microstructure of sample D; (D2) is the microstructure of sample D at higher magnification.
Fig. 9 is an SEM image of a cross section of the high hardness material coating sample shown in fig. 6 in background electron mode, wherein (a) is an SEM image of sample a, (B) is an SEM image of sample B, (C) is an SEM image of sample C, and (D) is an SEM image of sample D.
Detailed Description
The invention provides a high-hardness material coating structure and a preparation method thereof, wherein an amorphous alloy is used as a substrate or a transition layer, high-hardness material powder is sprayed on the amorphous alloy substrate or the transition layer by adopting a cold spraying process, and the amorphous alloy allows larger local shearing deformation, the high-hardness material powder is impacted on the amorphous alloy substrate or the transition layer at a speed exceeding a critical deposition speed in the cold spraying process, and the impact process causes large shearing deformation and shearing softening of an amorphous surface, so that the bonding strength between the amorphous alloy substrate or the transition layer and sprayed particles is effectively enhanced, the falling of the particles is obviously inhibited, and a compact, uniform and high-hardness coating is formed.
For the purposes of promoting an understanding of the principles and advantages of the disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same.
In a first exemplary embodiment of the present disclosure, a method of preparing a coating structure of a high hardness material is provided.
Fig. 1 is a schematic diagram of a method for preparing a coating of a high hardness material according to an embodiment of the present disclosure. Fig. 2 is a flow chart of a method of preparing a coating of a high hardness material according to an embodiment of the present disclosure.
In this embodiment, the apparatus implementing the methods of making embodiments of the present disclosure may be a commercial cold-dynamic spray system. Referring to fig. 1, the cold-dynamic spray system includes: powder feeder, gas supply device, gas heating device and spray gun. Wherein the spray gun comprises two input ends and one output end. The powder feeder is connected with one input end of the spray gun, and the gas heating device is connected with the other input end of the spray gun. The gas supply device is connected with the gas heating device, and the spraying gas supplied by the gas supply device is heated by the gas heating device and then is sent into the spray gun. Powder supplied by the powder feeder is also fed into the spray gun.
Referring to fig. 1, the pressure and temperature of the main air flow emitted from the nozzle are mainly adjusted during spraying. The main gas flow comprises powder carried by the spray gas. The pressure of the primary gas stream during the preparation of the high hardness material coating of embodiments of the present disclosure may be adjustable, for example, the pressure of the primary gas stream may be 100psi, 200psi, or any value between 100psi and 200psi, for example 150psi. The pressure of the powder feeder is also adjustable. In one embodiment, the pressure of the powder feeder may be set to be 50psi greater than the pressure of the main gas stream. In a preferred embodiment, the primary gas stream has a pressure of 100psi to 200psi and a temperature in the range of 250K to 500K.
In an embodiment of the present disclosure, the spray gun is a converging-diverging spray gun for accelerating the powder carried by the spray gas. In the cold-dynamic spray system described above, the converging-diverging spray gun is movable and may be gradually brought closer to the substrate to be sprayed. The speed of movement of the nozzle is adjustable, and an exemplary speed of movement of the nozzle may be 1cm/s. The path of the spray coating is programmable.
Referring to fig. 1, in this embodiment, the substrate to be sprayed is an amorphous alloy substrate/transition layer (meaning amorphous alloy as substrate, or amorphous alloy as transition layer), and the distance from the converging-diverging spray gun to the amorphous alloy substrate/transition layer is adjustable. In one embodiment, the distance between the converging-diverging spray gun and the amorphous alloy substrate/transition layer (in the left-right direction in fig. 1) is any value from 8mm to 15mm, for example, the distance may be 10mm.
Referring to fig. 2, a method for preparing a coating structure of a high hardness material of the present disclosure includes: step S11 and step S12.
In step S11, an amorphous alloy is used as a substrate or a transition layer.
In step S12, high-hardness material powder is sprayed on the amorphous alloy substrate or the transition layer by adopting a cold spraying process, and a high-hardness material compact coating is obtained on the amorphous alloy substrate or the transition layer.
In this embodiment, in step S11, the amorphous alloy is a nanocrystalline alloy or metallic glass. In the present disclosure, the shape of the amorphous alloy substrate or the transition layer used for spraying is not limited, and a disc shape is exemplified in this embodiment, and the diameter of the disc is 8mm and the thickness is 4mm, for example. The surface of the amorphous alloy substrate or the transition layer for the spray powder needs to be polished before the start of the spraying. The specific parameter settings for spraying the powder of the high hardness material using the cold spray process in step S12 may be initially evaluated according to a one-dimensional model of the particle velocity. Specific parameters include pressure and temperature of the main gas flow.
In one embodiment, the high hardness material powder is a tungsten carbide alloy powder having a mass ratio of tungsten to carbon of 10:1, the tungsten carbide alloy powder having a purity of greater than 99.9%.
In one embodiment, the tungsten carbide alloy powder has a carbon content of 6.1% -6.18%, a content of elemental carbon impurities of less than 0.05%, a mass percentage of Fe of 0.01% -0.02%, and a mass percentage of Mo of less than 0.01%.
In one embodiment, the high hardness material powder may be an industrial or commercial spray powder, such as an industrial tungsten carbide powder.
In one embodiment, the powder particles of the high hardness material powder have a characteristic size of 0.7 μm to 2 μm.
In one embodiment, the particles in the coating of high hardness material are 1 μm to 5 μm in size.
In an embodiment of the present disclosure, referring to fig. 1 and 2, the step S12 of spraying the powder of the high hardness material on the amorphous alloy substrate or the transition layer by using the cold spraying process includes: the high hardness material powder is fed into a powder feeder or converging-diverging spray gun for spraying. Wherein, nitrogen or compressed air is used as spraying gas, and the air pressure is 100 or 200 atmospheres; the pressure of the powder feeder was set to 50 atmospheres greater than the pressure of the main gas stream comprising the spray gas carrying the high hardness material powder.
In one embodiment, the pressure of the compressed air is above 15 atmospheres.
In one embodiment, four samples were prepared using steps S11, S12 and the pressure and temperature condition parameters of the spray coating according to table 1, sample a, sample B, sample C and sample D, respectively. In this example, the spraying time of each of the four samples was 4 seconds.
Table 1 examples of pressure and temperature parameters for each sample
After the spray coating was completed, a series of characterizations were performed on the samples. Estimating the particle velocity by a one-dimensional model; characterizing the topographical features of the coating by digital cameras, optical microscopy and Scanning Electron Microscopy (SEM); the mechanical properties of WC coatings were investigated by vickers hardness tester.
Fig. 3 is a surface morphology SEM image of a high hardness material coating prepared by the preparation method of the high hardness material coating according to an embodiment of the present disclosure.
Referring to fig. 3, the size of particles in the coating layer using the high hardness material according to the embodiment of the present disclosure falls approximately in the range of 1 μm to 3 μm.
The gas velocity in the lance can be expressed as follows based on an isentropic gas fluid model:
wherein v is g Is the gas velocity; m is Mach constant; gamma is the ratio of specific heat capacities; r is the gas constant; t is the temperature of the spraying gas; m is M W Is the molecular weight of the gas.
FIG. 4 is a graph of gas velocity in a lance versus axial position according to an embodiment of the disclosure. The gas velocity estimates corresponding to the samples a to D calculated by the above formula (1) are shown in fig. 4, where the axial direction refers to the axial direction of the spray gun, and in fig. 1, the gas velocity curves of the samples a and C overlap each other, the gas velocity curves of the samples B and D overlap each other, and the gas velocities of the samples B and D corresponding to a certain position along the axial direction are higher than the gas velocities of the samples a and C, so that it can be seen that the gas velocity can be significantly increased by increasing the gas temperature of the spray coating.
Further, in order to estimate the velocity of particles (particles, both meaning equivalent throughout) along the axial direction, it is first assumed that the powder carried by these spray gases is spherical particles. Particle axial velocity v according to one-dimensional particle dynamics model p The following formula can be used for calculation:
wherein D is the particle diameter; x is the axial position of the particle; ρ p Is the particle density; p (P) 0 Is a static pressure.
FIG. 5 is a graph of axial velocity of particles versus particle size according to an embodiment of the present disclosure. The relationship between the axial velocity of the particles and the diameter of the particles obtained by calculation using the above formula (2) is shown in fig. 5, and the result shows that the influence of the gas temperature on the axial velocity of the particles is not great.
However, heating the gas may increase the temperature of the particles and even the matrix, thereby increasing its plasticity. In practice, the working particles are not spherical, but irregular. From an aerodynamic point of view, the drag coefficient of non-spherical particles is greater than that of spherical particles, so the irregular shape of the particles facilitates acceleration of the particles. The first cold sprayed coating of the substrate surface is related not only to the particle velocity but also to the difference in properties between the particles and the substrate. Therefore, theoretical prediction of the first layer has a certain difficulty in practical application. But the formation of subsequent layers is effectively foreseeable.
According to the existing theory, the influence of process and material parameters on critical speed is summarized as the following expression:
V cri ＝667-0.014ρ p +0.08T m +10 -7 σ μ -0.4T (3)
wherein T is m Is the melting temperature (in degrees Centigrade) of the particles; sigma (sigma) μ Is the ultimate tensile strength or tensile strength of the particles; t is the temperature of the particles just ejected from the gun.
The critical speed of coating (coating) formation between WC-WC is 660m/s, i.e., the speed at which the tungsten carbide undergoes plastic deformation large enough to form a coating on the tungsten carbide substrate. In embodiments of the present disclosure, the critical speed of forming a dense coating on an amorphous alloy substrate is significantly less than 660m/s.
The analysis can be performed with reference to the actually prepared samples a to D for process optimization.
Fig. 6 is a schematic photograph of a sample of a coating of a high hardness material according to an embodiment of the present disclosure, wherein (a) is a photograph of sample a, (B) is a photograph of sample B, (C) is a photograph of sample C, and (D) is a photograph of sample D.
Referring to fig. 6 (a), in sample a, only half of the surface area is covered with the coating. From the analysis, it was found that, due to the lower particle velocity of sample a, only half of the surface area had the coating, and that the individual particles in the coating were loosely arranged. As the gas temperature increases, the substrate surface forms an uneven coating, but since the particle axial velocity along the axial direction is similar to sample a, and is also relatively low, the substrate edges remain bare without coating coverage, as shown with reference to fig. 6 (b). When the spraying speed reached the critical value, a uniform and dense coating was obtained, as shown in fig. 6 (c). However, once the speed exceeds the critical value, the coating is eroded by the following particles and many pits appear, as shown in fig. 6 (d).
Fig. 7 is a surface morphology SEM spectrum of the high hardness material coating sample shown in fig. 6, wherein (a) is a SEM spectrum of sample a, (B) is a SEM spectrum of sample B, (C) is a SEM spectrum of sample C, and (D) is a SEM spectrum of sample D. In FIG. 7, the scale has a size of 100. Mu.m.
Further details were studied by using an optical microscope. There is a distinct boundary in the center of sample a, as shown by the dashed line in fig. 7 (a). A sludge coating is formed on the left side and some large particles are inserted into the substrate on the right side. As the gas temperature increases, a relatively dense, but non-uniform coating forms on the substrate surface, but still leaves behind a few large particles on the coating, as shown with reference to fig. 7 (b). Once the spray speed reaches a critical value, a uniform coating can be produced without significant defects, as shown in fig. 7 (c). However, when the velocity is further increased and exceeds the critical value of the erosion formation coating, a number of cavities exceeding 200 μm are created, as shown with reference to fig. 7 (d).
FIG. 8 shows the microstructure of the coating sample of the high hardness material shown in FIG. 6 in secondary electron mode, (a 1) is the microstructure of sample A; (a 2) is the microstructure of sample a at higher magnification; (B1) is the microstructure of sample B; (B2) is the microstructure of sample B at higher magnification; (C1) is the microstructure of sample C; (C2) is the microstructure of sample C at higher magnification; (D1) is the microstructure of sample D; (D2) is the microstructure of sample D at higher magnification.
Comparing (a 2), (B2) and (C2) in fig. 8, it can be seen that although the low speed during spraying resulted in some weak areas in the coating, as indicated by the dark areas in (a 1) in fig. 8, the coating formed in sample a was much denser than the coating formed in samples B and C, i.e., sample a was more dense than samples B and C. The coating in sample C appears to be more uniform than the other coatings and the coating is not as dense as samples a and D, but it contains very few pores, as shown in comparison with (a 1) and (C2) in fig. 8 and (a 1), (a 2), (D1) and (D2) in fig. 8. The coating of sample D was the most dense, but many large particles and cavities were present, as shown with reference to fig. 8 (D1) and (D2).
Fig. 9 is an SEM image of a cross section of the high hardness material coating sample shown in fig. 6 in background electron mode, wherein (a) is an SEM image of sample a, (B) is an SEM image of sample B, (C) is an SEM image of sample C, and (D) is an SEM image of sample D.
Referring to fig. 9 (a) to (d), all samples had a particle layer thickness of less than 1 μm, which is consistent with the calculation results. As can be seen from fig. 9 (a), the substrate of sample a underwent very slight deformation, with only very fine particles covering the substrate. This facilitates the formation of the coating by attaching fine particles to the substrate in sample a. Referring to fig. 9 (B), the compactness and uniformity of sample B were inferior to those of samples a and C. From the cross-sectional view shown in fig. 9 (C), the uniformity and density of the coating in sample C can be determined, with the uniformity of the coating in sample C being better than that of the other samples A, B, D, but the density of sample C being smaller than that of sample a. Referring to fig. 9 (D), the substrate in sample D is subjected to large deformation due to the high particle velocity, but a dense and uniform coating is not formed due to erosion of large particles. Referring to fig. 9 (C), the substrate in sample C is subject to greater deformation than the substrate in sample B despite the low particle velocity. In addition to the particle velocity, the gas temperature for each sample was also different. Considering the presence of superplastic regions in the metallic glass substrate, it is believed that the combination of kinetic energy and gas temperature results in an increase in temperature and enhances the large deformation of sample C. Thus, based on the foregoing, the pressure of the main gas stream is preferably 130psi to 250psi and the temperature is preferably 250K to 500K, such as 280K, 300K, 320K, 350K, 380K, 400K, 420K, 450K, etc., the ranges described above include the endpoints. The spraying time is generally used for increasing the thickness of the coating, and the thickness is generally difficult to increase after the compact coating is formed, so that the meaning of prolonging the spraying time after the compact coating is formed is not great, and the spraying time for forming the coating can be adjusted in advance according to the actual spraying process.
In addition, the hardness of sample C was characterized. The mechanical properties of the coating in sample C were tested by vickers hardness tester. Hardness tests were performed, 10 times for loads of 500gf and 1000gf, respectively, each for a period of 10 s. The hardness values of the substrate, powder and coating are listed in table 2. The hardness of monolithic Bulk Metallic Glass (BMG) substrates showed a stable of about 530HV in these tests. In addition, in the test, the corresponding coating is a single-layer coating with the spraying time of 4s, so as to illustrate the influence of different spraying conditions on the compactness and uniformity of the coating.
TABLE 2 hardness of substrate, tungsten carbide powder, coating
In addition, an example of the disclosure also compares the preparation method of the amorphous alloy as a substrate or a transition layer of the disclosure with a coating obtained by a conventional preparation process, under the same experimental conditions, except for different substrates, other parameter conditions including temperature, pressure of air flow, spraying time and the like are the same, corresponding to the generation of concave with the particle size by spraying on a stainless steel substrate, the sprayed particles fall off, the appearance of the coating shows sparse coating, and the hardness of the coating is not high; the coating prepared by spraying on the amorphous alloy substrate of the embodiment of the disclosure has better density and hardness.
In an embodiment of the disclosure, the high hardness material powder is a tungsten carbide alloy powder, and the method for preparing the tungsten carbide alloy powder includes the following steps (a) to (c).
And (a) putting the raw materials of carbon and tungsten into a vacuum induction furnace according to preset components for smelting, respectively carrying out deslagging, refining, homogenizing and atomizing treatment, and drying and sieving to obtain a tungsten carbide alloy powder crude product.
In an embodiment of the present disclosure, the smelting temperature is 1400 ℃ to 1550 ℃, for example 1500 ℃.
And (b) carrying out solution treatment on the crude tungsten carbide alloy powder, and then quenching the crude tungsten carbide alloy powder to room temperature. The temperature of the solution treatment is 1050-1100 ℃, including end point values, such as 1080 ℃; the heat preservation time of the solution treatment is lh to 2 hours.
And (c) carrying out hydrogen reduction on the crude tungsten carbide alloy powder after water quenching to obtain the tungsten carbide alloy powder.
In one embodiment of the present disclosure, the hydrogen reduction is performed at any number of temperatures ranging from 200 ℃ to 300 ℃, such as 220 ℃, 240 ℃, 250 ℃, and the like. The reduction time is 1h to 3h, and may be, for example, 1h, 2h, or 3h.
In an embodiment of the disclosure, the method of atomization treatment is a vacuum gas atomization method or a plasma rotating electrode method.
In one embodiment of the present disclosure, the crude tungsten carbide alloy powder is spherical or spheroidic, with a particle size of less than 5 μm.
In one embodiment of the present disclosure, the hardness of the tungsten carbide alloy powder is 170-200.
In an embodiment of the present disclosure, the tungsten carbide alloy powder is spherical, near-spherical, or polygonal in shape.
In a second exemplary embodiment of the present disclosure, a high hardness material coating structure is provided. The high hardness material coating structure comprises: an amorphous alloy substrate or transition layer; and a coating of a high hardness material formed on the amorphous alloy substrate or the transition layer.
In one embodiment of the present disclosure, a dense coating of high hardness material is formed by spraying a powder of the high hardness material on an amorphous alloy substrate or transition layer using a cold spray process.
In one embodiment, the amorphous alloy is a nanocrystalline alloy or metallic glass.
In this embodiment, the high hardness material powder is a tungsten carbide alloy powder, wherein the mass ratio of tungsten to carbon is 10:1, and the purity of the tungsten carbide alloy powder is greater than 99.9%. In one embodiment, the tungsten carbide alloy powder has a carbon content of 6.1% -6.18%, a content of elemental carbon impurities of less than 0.05%, a mass percentage of Fe of 0.01% -0.02%, and a mass percentage of Mo of less than 0.01%.
In this embodiment, the hardness of the tungsten carbide alloy powder is 170 to 200.
In this embodiment, the tungsten carbide alloy powder is spherical, near-spherical, or polygonal in shape.
In summary, the present disclosure provides a coating structure of high hardness material and a method for preparing the same, in which an amorphous alloy is used as a substrate or a transition layer, and a cold spraying process is used to spray high hardness material powder on the amorphous alloy substrate or the transition layer, because the amorphous alloy allows greater local shear deformation, the high hardness material powder is impacted on the amorphous alloy substrate or the transition layer at a speed exceeding a critical deposition speed in the cold spraying process, and the impact process causes great shear deformation and shear softening of the amorphous surface, thereby effectively enhancing the bonding strength between the amorphous alloy substrate or the transition layer and sprayed particles, obviously inhibiting the falling of the particles, and forming a compact and high hardness coating.
Unless otherwise known, numerical parameters in this specification and the appended claims are approximations that may vary depending upon the desired properties sought to be obtained by the present disclosure. In particular, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". In general, the meaning of expression is meant to include a variation of + -10% in some embodiments, a variation of + -5% in some embodiments, a variation of + -1% in some embodiments, and a variation of + -0.5% in some embodiments by a particular amount.
While the foregoing embodiments have been described in some detail for purposes of clarity of understanding, it will be understood that the foregoing embodiments are merely illustrative of the invention and are not intended to limit the invention, and that any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the present disclosure are intended to be included within the scope of the present disclosure.

Claims (7)

1. A method for preparing a coating structure of a high hardness material, comprising:
using an amorphous alloy as a substrate or a transition layer;
spraying high-hardness material powder on the amorphous alloy substrate or the transition layer by adopting a cold spraying process, obtaining a high-hardness material compact coating on the amorphous alloy substrate or the transition layer,
the amorphous alloy is nanocrystalline alloy or metallic glass, and the spraying of the high-hardness material powder on the amorphous alloy substrate or the transition layer by adopting a cold spraying process comprises the following steps:
feeding the high-hardness material powder into a powder feeder, and spraying by a converging-diverging spray gun;
wherein, nitrogen or compressed air is used as spraying gas, the main air flow comprises spraying gas carrying high-hardness material powder, and the air pressure of the main air flow is 100-200 atmospheres; the pressure of the powder feeder is set to be 50 atmospheres higher than the pressure of the main air flow, the temperature of the main air flow is 250K-500K, and the air pressure of the compressed air is above 15 atmospheres;
and when spraying, the distance from the converging diffusion spray gun to the amorphous alloy substrate or the transition layer is 8-15 mm.
2. The method of claim 1, wherein the main gas stream pressure is 150 to 200 atmospheres.
3. The method of claim 1, wherein the converging-diverging spray gun is 10mm from the amorphous alloy substrate or the transition layer when spraying.
4. The method according to claim 1, wherein,
the high-hardness material powder is tungsten carbide alloy powder, wherein the mass ratio of tungsten to carbon is 10:1, and the purity of the tungsten carbide alloy powder is more than 99.9%;
the characteristic size of the powder particles of the high-hardness material powder is 0.7-2 mu m;
the size of the particles in the high-hardness material coating is 1-5 mu m.
5. The method according to claim 4, wherein the tungsten carbide alloy powder has a carbon content of 6.1 to 6.18%, a content of elemental carbon impurities of less than 0.05%, a mass percentage of Fe of 0.01 to 0.02%, and a mass percentage of Mo of less than 0.01%.
6. The method of claim 4, wherein the tungsten carbide alloy powder is spherical, near-spherical or polygonal in shape.
7. A high hardness material coating structure, characterized in that the high hardness material coating structure comprises:
an amorphous alloy substrate or transition layer; and
a dense coating of a high hardness material formed on an amorphous alloy substrate or a transition layer, wherein the amorphous alloy is a nanocrystalline alloy or metallic glass, and the high hardness material coating is prepared by the preparation method of any one of claims 1 to 6.
CN202210605175.XA 2020-06-30 2020-06-30 High-hardness material coating structure and preparation method thereof Active CN114990541B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210605175.XA CN114990541B (en) 2020-06-30 2020-06-30 High-hardness material coating structure and preparation method thereof

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202010616217.0A CN111763938A (en) 2020-06-30 2020-06-30 High-hardness material coating structure and preparation method thereof
CN202210605175.XA CN114990541B (en) 2020-06-30 2020-06-30 High-hardness material coating structure and preparation method thereof

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
CN202010616217.0A Division CN111763938A (en) 2020-06-30 2020-06-30 High-hardness material coating structure and preparation method thereof

Publications (2)

Publication Number Publication Date
CN114990541A CN114990541A (en) 2022-09-02
CN114990541B true CN114990541B (en) 2023-07-21

Family

ID=72724343

Family Applications (2)

Application Number Title Priority Date Filing Date
CN202010616217.0A Pending CN111763938A (en) 2020-06-30 2020-06-30 High-hardness material coating structure and preparation method thereof
CN202210605175.XA Active CN114990541B (en) 2020-06-30 2020-06-30 High-hardness material coating structure and preparation method thereof

Family Applications Before (1)

Application Number Title Priority Date Filing Date
CN202010616217.0A Pending CN111763938A (en) 2020-06-30 2020-06-30 High-hardness material coating structure and preparation method thereof

Country Status (1)

Country Link
CN (2) CN111763938A (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115233208B (en) * 2022-07-07 2023-10-03 国网宁夏电力有限公司超高压公司 High-voltage isolating switch surface repairing method and device based on supersonic laser deposition

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103993314A (en) * 2014-06-10 2014-08-20 东莞台一盈拓科技股份有限公司 Surface treatment method of amorphous alloy
CN104278267A (en) * 2014-10-30 2015-01-14 九江学院 Multi-scale metal ceramic coating and preparation method thereof
CN108315638B (en) * 2018-01-31 2020-04-24 西北有色金属研究院 Iron-based alloy powder for cold spraying and preparation method and application thereof
CN109504965B (en) * 2018-11-26 2020-02-07 海洋化工研究院有限公司 High-temperature corrosion-resistant anti-skid coating with iron-based composite structure and preparation method thereof

Also Published As

Publication number Publication date
CN111763938A (en) 2020-10-13
CN114990541A (en) 2022-09-02

Similar Documents

Publication Publication Date Title
US5939146A (en) Method for thermal spraying of nanocrystalline coatings and materials for the same
Kim et al. Fabrication of WC–Co coatings by cold spray deposition
US7553385B2 (en) Cold gas dynamic spraying of high strength copper
Ghadami et al. Effect of bond coat and post-heat treatment on the adhesion of air plasma sprayed WC-Co coatings
EP1227169B1 (en) Spray powder and method for its production
EP1666636A1 (en) Vacuum cold spray process
Yoon et al. Deposition behavior of bulk amorphous NiTiZrSiSn according to the kinetic and thermal energy levels in the kinetic spraying process
Blazdell et al. Plasma spraying of submicron ceramic suspensions using a continuous ink jet printer
EP2118331A2 (en) Amorphous-nanocrystalline-microcrystalline coatings
Smirnov et al. Receiving finely divided metal powder by inert gas atomization
US20220152705A1 (en) Process for forming wrought structures using cold spray
Xie et al. Comparison of microstructure and tribological properties of plasma, high velocity oxy-fuel and detonation sprayed coatings from an iron-based powder
WO2005079209A2 (en) Nanocrystalline material layers using cold spray
US5433978A (en) Method of making quasicrystal alloy powder, protective coatings and articles
Shin et al. Effect of particle parameters on the deposition characteristics of a hard/soft-particles composite in kinetic spraying
CN114990541B (en) High-hardness material coating structure and preparation method thereof
KR20080065480A (en) Method for coating with copper-tungsten composite material by using cold spraying process
Lee et al. Fabrication of porous Al alloy coatings by cold gas dynamic spray process
CN111250693B (en) High-entropy alloy powder for additive remanufacturing and preparation method thereof
Kumar et al. Characterization and comparison between APS coatings prepared from ball milled and plasma processed nickel–aluminium powders
CN113308688A (en) Nano bulk crystal metal material and preparation method thereof
CN115896774A (en) Method for preparing niobium coating by cold spraying technology
Song et al. Formation of metastable phases in a spray deposited 2024 aluminium alloy
Jodoin et al. Cold spray deposition of metastable alloys
Paliwal et al. An experimental study of powder melting during low pressure plasma deposition

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant