CN108118339B - Corrosion-resistant and wear-resistant composite coating with cladding-like texture and preparation method thereof - Google Patents

Abstract

Class involucrum texture type corrosion-proof wear composite coating and preparation method thereof, coating is made of class involucrum textural composite area, metallurgical melting transition region, the area that extends influence, and thickness can adjust within the scope of 2 ~ 5mm；The class involucrum textural composite area is evenly distributed between spherical alloy region by the hard-phase particles of fine uniform, and between hard particles is alloy, and the GO thin slice also with nearly singular integral irregular distribution forms the involucrum for surrounding alloyed region therebetween.Preparation method step are as follows: (1) substrate pre-processes；(2) composite powder is blended, and GO, hard particles and Co-based alloy powder are placed in distilled water, are uniformly mixed, and obtains coated composite powder end；(3) coating coats, in metal base surface coating Co-based alloy powder as transition zone before mixed-powder coating；(4) class involucrum texture type coating is sintered, and pre-burning part is put into vacuum sintering furnace, heats up and keeps the temperature minute, furnace cooling is come out of the stove to 150 DEG C, is air-cooled to room temperature, obtains coating.

Description

Corrosion-resistant and wear-resistant composite coating with cladding-like texture and preparation method thereof

technical field

The invention belongs to the surface treatment technology of metal materials, and relates to the preparation technology of a corrosion-resistant and wear-resistant nickel-based composite coating.

Background technique

Nickel-based composite powder has good process formability, corrosion and wear resistance, and high temperature resistance, and is widely used in various coating preparation methods. Due to the composition, content and coating forming method of nickel-based composite powder The difference will greatly affect the final structure and morphology of the coating, thus affecting the corrosion resistance and friction resistance of the coating. In the friction and wear test, the general coating peels off in a large area on the surface of the sample, and produces a large number of furrows along the friction direction, especially under harsh conditions such as high temperature, high pressure, high speed, heavy load, etc., the wear is intensified. In the electrochemical test, a large number of pits generally appear on the surface of the coating, not only uniform corrosion, but also local corrosion such as pitting corrosion.

Studies have shown that cladding-like texture can significantly improve the friction and corrosion properties of materials. The existence of graphene oxide acts as a lubricant, which can lubricate the surface of the friction pair, which can reduce the wear of the friction pair, reduce the friction coefficient, and at the same time, the texture can also improve the load-carrying capacity of the material. Graphene oxide flakes have the characteristics of insulation. Although they are partially reduced at high temperatures, the resistance does not change much. The unique cladding-like texture makes it difficult for the material to corrode and effectively reduces the corrosion rate.

Vacuum cladding technology is a modern surface metallurgy technology, which can improve the wear resistance, high temperature oxidation resistance and thermal fatigue resistance of the metal surface. The method is to pre-coat the metal powder with specific properties on the surface of the parts, and after firing, the surface of the parts will be coated with special properties to achieve the purpose of improving the service life of the parts.

The whole process of vacuum cladding is carried out in a certain vacuum environment, so the workpiece is not easy to be oxidized; the surface of the coating is smooth and of good quality; the composition of the composite powder of the cladding layer is controllable, and different formulas can be selected according to different experimental purposes; The thickness of the cladding layer is adjustable, and a coating with better performance can be obtained in a wide range; the metallurgical bond between the cladding layer and the surface of the part is realized, which is relatively firm.

Literature review and related experiments show that the cladding-like texture coating exhibits excellent friction and corrosion properties. It can reduce the friction coefficient and improve wear resistance; it can hinder the occurrence of corrosion, reduce the corrosion rate and improve corrosion resistance. However, there are still some problems in the preparation of cladding-like textured coatings, such as single technology, complicated process, high cost, thin thickness, and low bonding strength with the substrate.

Contents of the invention

The purpose of the invention is to improve the corrosion resistance and friction resistance performance of the coating.

The invention is a cladding-like texture-like corrosion-resistant and wear-resistant composite coating and a preparation method thereof. The cladding-like texture-like corrosion-resistant and wear-resistant composite coating is composed of a cladding-like texture composite zone 1, The metallurgical fusion transition zone 2 and the diffusion-influenced zone 3 are formed; the metallurgical bonding between the textured coating and the substrate is of high strength; Between the regions, while the hard particles are alloys, and there are almost continuous and irregularly distributed GO flakes forming a shell surrounding the alloy area. GO is graphene oxide, and the shell texture is three-dimensional in the composite area. Reticular distribution; the mesh size of the shell-like texture is 60~80um, and the width of the texture "tendon" is 15~30um; in three-dimensional space, each mesh is irregularly distributed between hard phase particles and The GO cladding approximately surrounds the spherical alloy region, and the distance between hard particles is 5~10um.

A method for preparing a shell-like textured corrosion-resistant and wear-resistant composite coating, the steps of which are:

(1) Substrate pretreatment: After removing the oxide layer with a grinding wheel, the surface of the substrate is polished with sandpaper until smooth and bright, then cleaned with acetone and absolute ethanol to remove oil stains, and finally dried for later use;

(2) Composite coating mixing: Weigh the nickel-based alloy powder, the preset amount of hard particles and GO solution respectively, put them in a beaker and stir them evenly, then put them in an evaporating dish, and put them in a muffle furnace Dry, and finally grind and mix evenly with a ball mill;

(3) Preparation of prefabricated layer: pre-coat a layer of nickel-based alloy powder prepared with a binder on the surface of the substrate as a transition layer, with a thickness of 0.5~2mm, and then evenly coat the composite powder with a binder Covered on the transition layer, the thickness is 2~4mm;

(4) Composite coating sintering: After drying the product obtained in step (3) naturally in the shade and then drying, put it into a vacuum carbon tube furnace for sintering, pump the vacuum to 6.67×10 ^-2 Pa, raise the temperature to 1060°C and Add the type and content of hard phase particles and keep warm for 5 to 45 minutes, then cool to 150°C with the furnace and air-cool to room temperature to obtain a nickel-based composite coating with corrosion and wear resistance.

The benefit of the invention is that the characteristics of the vacuum cladding technology are fully utilized to obtain a smooth and dense coating. In particular, the composition of the invention is controllable, and a certain amount of GO is added to significantly improve the corrosion resistance of the coating by nearly two orders of magnitude. Adding a certain amount of hard particles can significantly improve the wear resistance of the coating. The process of the invention is simple to operate and environmentally friendly. Under a certain degree of vacuum, for the first time, hard particles and GO were used as additive phases at the same time, and the heating rate, cooling rate, and heat flow direction were controlled to prepare a corrosion-resistant and wear-resistant nickel-based composite coating. The thickness of the coating obtained by sintering is about 4mm, and it is metallurgically bonded with the substrate, with firm bonding and strong bearing capacity.

Description of drawings

Fig. 1 is a schematic longitudinal section of the present invention.

Detailed ways

The invention is a cladding-like textured corrosion-resistant and wear-resistant composite coating and a preparation method thereof. The cladding-like textured corrosion-resistant and wear-resistant composite coating is shown in Figure 1. The texture composite zone 1, the metallurgical fusion transition zone 2, and the diffusion influence zone 3; the textured coating and the substrate are metallurgically bonded with high strength; the cladding-like texture composite zone is composed of fine and uniform hard phase The particles are evenly distributed between the spherical alloy regions, while the hard particles are alloys, and there are almost continuous and irregularly distributed GO flakes in between to form a shell surrounding the alloy region. GO is graphene oxide, and the shell texture is in the The composite area is distributed in a three-dimensional network; the mesh size of the shell-like texture is 60~80um, and the width of the texture "tendon" is 15~30um; in the three-dimensional space, each mesh is a hard phase particle The GO cladding is irregularly distributed and approximately surrounds the spherical alloy area, and the distance between hard particles is 5-10um.

In the aforementioned clad-like textured corrosion-resistant and wear-resistant composite coating, the hard phase particles are WC hard particles.

In the cladding-like texture-type corrosion-resistant and wear-resistant composite coating described above, the cladding-like texture composite zone 1 is composed of nickel-based solid solution, eutectic structure Ni ₃ Si, Ni ₃ B and hard phase particles, oxide Composed of graphene sheets and a small amount of reduced carbon; metallurgical fusion transition layer region 2 consists of solid solution, eutectic phase Ni ₃ Si, Ni ₃ B and precipitated hard phases CrB, Cr ₇ C ₃ , Cr ₂₃ C ₆ and near the coating area The growing nickel-based solid solution and the iron-based solid solution growing in a rod shape near the substrate; the diffusion-affected zone 3 is composed of pearlite and ferrite.

The preparation method of the above-mentioned cladding texture structure anti-corrosion and wear-resistant composite coating, the steps are:

(1) Substrate pretreatment: After removing the oxide layer with a grinding wheel, the surface of the substrate is polished with sandpaper until smooth and bright, then cleaned with acetone and absolute ethanol to remove oil stains, and finally dried for later use;

(2) Composite coating mixing: Weigh the nickel-based alloy powder, the preset amount of hard particles and GO solution respectively, put them in a beaker and stir them evenly, then put them in an evaporating dish, and put them in a muffle furnace Dry, and finally grind and mix evenly with a ball mill;

(3) Preparation of prefabricated layer: pre-coat a layer of nickel-based alloy powder prepared with a binder on the surface of the substrate as a transition layer, with a thickness of 0.5~2mm, and then evenly coat the composite powder with a binder Covered on the transition layer, the thickness is 2~4mm;

(4) Composite coating sintering: After drying the product obtained in step (3) naturally in the shade and then drying, put it into a vacuum carbon tube furnace for sintering, pump the vacuum to 6.67×10 ^-2 Pa, raise the temperature to 1060°C and Add the type and content of hard phase particles and keep warm for 5 to 45 minutes, then cool to 150°C with the furnace and air-cool to room temperature to obtain a nickel-based composite coating with corrosion and wear resistance.

In the preparation method of the above-mentioned shell-like textured corrosion-resistant and wear-resistant composite coating, the hard phase particles WC are added in step (2), the mass percentage is: 20%~40%, and the particle size is 5 ~10um with irregular geometry.

In the preparation method of the cladding-like texture-type corrosion-resistant and wear-resistant composite coating described above, GO is added in step (2), and its mass percentage is: 0.4%~1.2%. The diameter of graphene oxide flakes is about 20um, the average thickness is less than 5nm, and the number of layers is 1~3.

In the preparation method of the above-mentioned shell-like textured corrosion-resistant and wear-resistant composite coating, in step (3), the coated sample is naturally dried in the shade, and then placed in a muffle furnace with a set temperature of 200°C. Take it out after 2 hours of heat preservation, and finally sinter in a ZT-18-22 vacuum carbon tube furnace with a vacuum degree of 6.67×10 ^-2 Pa ~ 4×10 ^-3 Pa, a heating rate of 60°C/min, and a heat preservation temperature of 1060°C. Cool to 150°C with the furnace for 5~45min.

The technical solution of the present invention will be further described below in conjunction with specific embodiments.

The invention relates to a shell-like textured corrosion-resistant and wear-resistant composite coating and a preparation method thereof. The corrosion-resistant and friction-resistant nickel-based composite powder includes nickel-based alloy powder, WC and GO. Among them, the particle size of nickel-based alloy powder is in the range of 48~60um, the particle size of WC is in the range of 5~10um, and the diameter of GO nanoflakes is about 20um, the thickness is less than 5nm, and the number of layers is 1~3.

Carry out 3 groups of experiments to the above-mentioned a kind of cladding texture structure anti-corrosion and wear-resistant composite coating and its preparation method to illustrate, wherein only the content of graphene oxide is different, the specific operation steps are as follows:

(1) Substrate pretreatment: After removing the oxide layer with a grinding wheel, the surface of the substrate is polished with sandpaper until it is smooth and bright, then cleaned with acetone and absolute ethanol to remove oil stains, and finally dried for later use;

(2) Composite coating mixing: Weigh the nickel-based alloy powder and a certain amount of WC and GO solutions set in the experiment, respectively, put them in a beaker and stir evenly, then put them in an evaporating dish, and put them in a muffle furnace Dry, and finally grind and mix evenly with a ball mill;

(3) Preparation of prefabricated layer: pre-coat a layer of nickel-based alloy powder prepared with a binder on the surface of the substrate as a transition layer, with a thickness of 0.5~2mm, and then evenly coat the composite powder with a binder Covered on the transition layer, the thickness is 2~4mm;

(4) Composite coating sintering: After the product obtained in step (3) is dried in the shade naturally, put it into a ZT-18-22 vacuum carbon tube furnace for sintering, and the vacuum degree is pumped to 6.67×10 ^-2 Pa , heated up to 1060°C and kept warm, cooled to 150°C with the furnace and air-cooled to room temperature to obtain a nickel-based composite coating with corrosion resistance and wear resistance.

In the above-mentioned step (1), after the base material is removed with a grinding wheel, it is polished with 60 mesh, 120 mesh, 240 mesh, 400 mesh, 600 mesh, and 800 mesh sandpaper until it is smooth and bright, and then it is polished with acetone and Wash with absolute ethanol to remove oil stains, and finally dry for later use.

In the above step (2), WC and GO are used as the added phase at the same time, wherein the particle size of WC is 5~10um, has an irregular geometry, the hardness is about 2350HV, and the melting point is 2775°C; nickel-based alloy powder Ni-Cr -B-Si, the melting point is 1000℃, the particle size of nickel-based alloy powder is 48~60um.

Among them, the diameter of GO (graphene oxide) flakes is about 20um, the average thickness is less than 5nm, and the number of layers is 1~3.

In the above step (3), the coated sample is naturally dried in the shade, then placed in a muffle furnace, set the temperature at 200°C, and taken out after 2 hours of heat preservation, and finally placed in a ZT-18-22 vacuum carbon Sintering in a tube furnace with a vacuum degree of 6.67×10 ^-2 Pa to 4×10 ^-3 Pa, a heating rate of 60°C/min, holding at 1060°C for 5 minutes, cooling to 150°C, and air cooling to room temperature to obtain Corrosion-resistant nickel-based composite coating.

The content of WC in the above-mentioned nickel-based composite powder is 20%-40%.

The content of GO in the nickel-based composite powders described above was 0.4 wt.% in Experiment 1.

The content of GO in the nickel-based composite powder described above was 0.8 wt.% in Experiment 2.

The content of GO in the nickel-based composite powder described above was 1.2 wt.% in Experiment 3.

Polarization curves were tested with an electrochemical workstation, and the self-corrosion potential and corrosion current density of the cladding layer samples were obtained through linear fitting calculations. The microstructure of the cladding layer was observed with a JSM-6700E scanning electron microscope (SEM), and the samples were analyzed with a JSM-5600 energy dispersive spectrometer (EDS) and an EPMA-1600 electron probe (EPMA). The distribution and change of elements were analyzed by D/max-2400 X-ray diffractometer (XRD) to analyze the phase composition of the cladding layer.

The above-mentioned sintered products were cut into small test pieces perpendicular to the coating direction with a wire cutting machine, and then sandpaper (60 mesh, 120 mesh, 240 mesh, 400 mesh, 600 mesh, 800 mesh, 1000 mesh, 1200 mesh, 1500 mesh) mesh, 2000 mesh) and polish the cross-section to be tested to meet the metallographic sample standard. Solder the copper wires on the coating surface with soldering, and then seal the other surfaces except the surface to be tested with polymer sealant. Inject an appropriate amount of NaCl solution into the tee pipe, put it in a constant temperature water bath at 25°C and let it stand for 30 minutes, then connect the wires of each electrode to test the polarization curve. In this paper, a standard three-electrode system is selected, the working electrode is the coated surface, the auxiliary electrode is platinum, and the saturated calomel cell is the reference electrode. In the test, the scanning speed is 0.005V/s, the initial potential is -1V, and the termination potential is 1V. Before each test starts, the sample must be placed in a water bath for 30 minutes, and the stable value of 3 experiments is taken as the experimental data.

In Experiment 1 above, the content of graphene oxide is 0.4wt.%, its corrosion potential is -0.488V, and its corrosion current density is 1.43E-08 (A/cm ² ).

In Experiment 2 above, the content of graphene oxide was 0.8wt.%, its corrosion potential was -0.580V, and its corrosion current density was 1.62E-08 (A/cm ² ).

In Experiment 3 above, the content of graphene oxide was 1.2wt.%, its corrosion potential was -0.320V, and its corrosion current density was 2.02E-07 (A/cm ² ).

According to literature review, in other vacuum cladding experiments, the maximum corrosion potential of nickel-based composite powder coatings with different compositions is about -0.462 V, and the corrosion current density is 1.669E-06 (A/cm ² ). The results of the previous friction experiment show that a certain amount of WC is added to the Ni-based alloy powder to obtain a three-dimensional textured composite coating. An order of magnitude, the friction coefficient is lower than that of the pure Ni-based alloy cladding layer to a certain extent.

The coating of the invention is dense, the thickness can reach 4mm, and has excellent corrosion resistance and wear resistance. The preparation process of the corrosion-resistant and wear-resistant composite coating includes substrate pretreatment, mixing of composite powder, preparation of the prefabricated layer and sintering of the coating. Particle type, vacuum degree, sintering heating rate and cooling rate, and heat flow direction to obtain a corrosion-resistant and wear-resistant coating. The coating and the substrate have a fusion diffusion transition layer, that is, a metallurgical bond between the coating and the substrate, and its bonding strength is high. The invention adopts conventional vacuum cladding technology, has good practicability and controllability, and is convenient for popularization and application.

The above embodiments have described the basic principles and main features of the present invention. The present invention is not limited by the above embodiments. What are described in the above embodiments and description are only to illustrate the principles of the present invention. As long as the technical principles and method concepts of the present invention are adopted Various insubstantial improvements, or direct application of the concept and technical solutions of the present invention to other occasions without improvement, all fall within the protection scope of the present invention.

Claims (7)

1. class involucrum texture type corrosion-proof wear composite coating, it is characterized in that the coating is by class involucrum textural composite area (1), smelting Gold fusion transition region (2), the area that extends influence (3) are constituted；It is the higher metallurgical bonding of intensity between texture coating and matrix；It is described Class involucrum textural composite area is evenly distributed between spherical alloy region by the hard-phase particles of fine uniform, and hard particles it Between be alloy, therebetween also with nearly singular integral irregular distribution GO thin slice formed surround alloyed region involucrum, GO i.e. aoxidize Graphite alkenes, involucrum texture are in 3 D stereo net distribution in recombination region；Class involucrum texture mesh size is 60 ~ 80um, Texture " grain " width is 15 ~ 30um；In three dimensions, each mesh be distributed between hard-phase particles it is irregular and Approximation surrounds the GO involucrum in spherical alloy region, and spacing is 5 ~ 10um between hard particles.

2. class involucrum texture type corrosion-proof wear composite coating according to claim 1, it is characterised in that hard-phase particles are WC hard particles.

3. class involucrum texture type corrosion-proof wear composite coating according to claim 1, it is characterised in that the class involucrum is knitted Structure recombination region (1) is by Ni-based solid solution, eutectic structure Ni₃Si、Ni₃B and hard-phase particles, graphene oxide sheet and it is a small amount of also Former carbon composition；Metallurgical melting transition zone area (2) is by solid solution, eutectic phase Ni₃Si、Ni₃B and precipitation hard phase CrB, Cr₇C₃ 、Cr₂₃C₆It is formed with the Ni-based solid solution close to coated areas growth and close to matrix in the iron-based solid solution of rodlike growth； The area (3) that extends influence is made of pearlite and ferrite.

4. the preparation method of class involucrum texture type corrosion-proof wear composite coating according to claim 1, which is characterized in that its Step are as follows:

(1) substrate pre-processes: after substrate surface removes removing oxide layer with grinding wheel, be polishing to smooth with sand paper, then with acetone with Washes of absolute alcohol removes degreasing, is finally dried for standby；

(2) composite coating is blended: the hard particles and GO solution of Co-based alloy powder and predetermined amount being weighed respectively and are placed on burning It stirs evenly, then is placed it in evaporating dish in cup, be put into Muffle furnace drying, be finally uniformly mixed with ball mill grinding；

(3) preparation of preformed layer: one layer is coated in substrate surface in advance and uses the Co-based alloy powder of binder modulation as transition Layer is uniformly coated on transition zone, with a thickness of 2 ~ 4mm with a thickness of 0.5 ~ 2mm, then after composite powder is modulated with binder；

(4) composite coating is sintered: the product that step (3) obtains being dried in the shade after drying again naturally, is put it into vacuum carbon tube furnace burning Knot, vacuum degree are evacuated to 6.67 × 10^-2Pa is warming up to 1060 DEG C and according to the type and content heat preservation 5 ~ 45 that hard-phase particles are added Minute is differed, and furnace cooling comes out of the stove to 150 DEG C and is air-cooled to room temperature, obtains the Ni base composite coating with corrosion-proof wear.

5. the preparation method of class involucrum texture type corrosion-proof wear composite coating according to claim 4, it is characterized in that step (2) hard-phase particles WC, mass percent are added in are as follows: 20% ~ 40%, particle size is 5 ~ 10um, is had irregular Geometry.

6. the preparation method of class involucrum texture type corrosion-proof wear composite coating according to claim 4, it is characterized in that step (2) GO, mass percent are as follows: 0.4% ~ 1.2% are added in.Graphene oxide wafer diameters size is 20um or so, average thickness It spends and is less than 5nm, 1 ~ 3 layer of the number of plies.

7. the preparation method of class involucrum texture type corrosion-proof wear composite coating according to claim 4, it is characterized in that step (3) sample that coating finishes is dried in the shade naturally in, then is placed in Muffle furnace, 200 DEG C of set temperature, heat preservation is taken out after 2 hours, most It is sintered in ZT-18-22 type vacuum carbon tube furnace afterwards, vacuum degree is 6.67 × 10^-2Pa ~ 4×10^-3Pa, heating rate 60 DEG C/min, 150 DEG C are cooled to the furnace in 1060 DEG C of 5 ~ 45min of heat preservation comes out of the stove.