1. The nano ceramic particle reinforced metal matrix composite coating for the surface of the cold roll is characterized by comprising 70-95 mass percent of FeCrBSi and 5-30 mass percent of Cr₃C₂。

2. The nano-ceramic particle reinforced metal matrix composite coating for the surface of a cold roll according to claim 1, wherein the coating thickness is 0.30-0.40 mm.

3. The nano-ceramic particle reinforced metal matrix composite coating for a cold roll surface of claim 1, wherein said Cr is₃C₂Comprises nano Cr₃C₂And micron Cr₃C₂。

4. The nano-ceramic particle reinforced metal matrix composite coating for cold roll surfaces of claim 3, wherein said Cr is₃C₂Middle nanometer Cr₃C₂Is 50 percent.

5. The nano-ceramic particle reinforced metal matrix composite coating for cold roll surfaces of claim 3, wherein said micro Cr is₃C₂The particle size of the powder is 5 to 50 μm.

6. The nano-ceramic particle reinforced metal matrix composite coating for the surface of a cold roll according to claim 3, wherein the nano-Cr is₃C₂The particle size of the powder is 10-800 nm.

7. The nano-ceramic particle reinforced metal matrix composite coating for the surface of a cold rolling roll according to claim 1, wherein the powder particle size of FeCrBSi is 15 μm to 50 μm.

8. The preparation method of the nano ceramic particle reinforced metal matrix composite coating for the surface of the cold rolling roller according to the claims 1 to 7, characterized by comprising the following steps:

s1: weighing the raw material powder according to a proportion, fully mixing to obtain coating powder, and packaging;

s2: cleaning the surface of the cold-work die steel cold roll by using alcohol, checking whether the surface of the cold roll has defects, and then measuring and recording the roll profile diameter;

s3: carrying out sand blasting treatment by using an automatic sand blasting machine, wherein the surface roughness Ra of the sand blasted cold roll surface is required to be 0.1-0.3 mu m;

s4: preheating the mixed coating powder at 80 +/-10 ℃ for more than 2 hours, and preparing the cold-rolling roller coating by adopting air fuel supersonic flame spraying equipment.

9. The method for preparing the nano ceramic particle reinforced metal matrix composite coating for the surface of the cold rolling roll according to claim 8, wherein the sand blasting material in the step S3 is 24-mesh white corundum, the angle of a spray gun is 90 +/-10 degrees, and the air pressure is 5kg/cm²The distance from the spray gun to the surface of the cold roll is 400 mm and 600 mm.

10. The method for preparing the nano ceramic particle reinforced metal matrix composite coating for the surface of the cold rolling roller according to claim 8, wherein the spraying process parameters in the step S4 are as follows: the powder feeding rate is 50-70g/min, the oxygen flow rate is 200-240L/min, the air flow rate is 330-370L/min, the propane flow rate is 65-85L/min, and the gun distance is 100-200 mm.

Background

In the metallurgical industry, a cold roll is required to bear a large rolling force and a large impact load force, and has a severe mutual friction action with a product, so that the phenomena of abrasion, peeling, roll sticking and the like on the surface of the cold roll are caused; the traditional method for protecting the surface of the cold roll is chromium electroplating, but the electroplating process can cause pollution and harm to the surrounding environment, organisms and the like, and the method is contrary to the concepts of green development, sustainable development and the like; other surface engineering technologies, such as induction heating quenching, surfacing, physical vapor deposition, laser cladding and the like, have some defects, such as high hardenability and crack sensitivity, poor bonding force between a coating and a matrix, high equipment cost, surface microcrack and the like; at present, a hot spraying technology is adopted to prepare a coating with WC and Co components on the surface of a cold roll, but the cold roll using the coating has the defects of low bonding strength and poor toughness; there is therefore a need to develop a new type of coating for the surface of cold rolls.

In view of the above-mentioned drawbacks, the inventors of the present invention have finally obtained the present invention through a long period of research and practice.

Disclosure of Invention

The invention aims to solve the problems of low bonding strength and poor toughness of the surface coating of the existing cold roll and provides a nano ceramic particle reinforced metal matrix composite coating for the surface of the cold roll and a preparation method thereof.

In order to achieve the purpose, the invention discloses a nano ceramic particle reinforced metal matrix composite coating for the surface of a cold roll, which comprises 70-95% of FeCrBSi and 5-30% of Cr by mass₃C₂。

The thickness of the coating is 0.30-0.40 mm.

The Cr is₃C₂Comprises nano Cr₃C₂And micron Cr₃C₂。

The Cr is₃C₂Middle nanometer Cr₃C₂Is 50 percent.

The micron Cr₃C₂The particle size of the powder is 5-50 mu m, and the nano Cr₃C₂The particle size of the powder is 10-800 nm

The particle size of the FeCrBSi powder is 15-50 μm.

The invention also discloses a preparation method of the nano ceramic particle reinforced metal matrix composite coating for the surface of the cold roll, which comprises the following steps:

s1: weighing the raw material powder according to a proportion, fully mixing to obtain coating powder, and packaging;

s2: cleaning the surface of the cold-work die steel cold roll by using alcohol, checking whether the surface of the cold roll has defects, and then measuring and recording the roll profile diameter;

s3: carrying out sand blasting treatment by using an automatic sand blasting machine, wherein the surface roughness Ra of the sand blasted cold roll surface is required to be 0.1-0.3 mu m;

s4: preheating the mixed coating powder at 80 +/-10 ℃ for more than 2 hours, and preparing the cold-rolling roller coating by adopting air fuel supersonic flame spraying equipment.

In the step S3, the sand blasting material is 24-mesh white corundum, the angle of the spray gun is 90 +/-10 degrees, and the air pressure is 5kg/cm²The distance from the spray gun to the surface of the cold roll is 400 mm and 600 mm.

The spraying process parameters in the step S4 are as follows: the powder feeding rate is 50-70g/min, the oxygen flow rate is 200-240L/min, the air flow rate is 330-370L/min, the propane flow rate is 65-85L/min, and the gun distance is 100-200 mm.

Cr₃C₂The ceramic coating has good wear resistance, but poor bonding performance, and carbide particles exist as a strengthening phase in the composite coating. The FeCrBSi alloy has similar expansion coefficient and thermal conductivity with cold-work die steel, and the alloy coating has higher bonding strength but poorer wear resistance. Adding micron and nanometer ceramic reinforced phase Cr into FeCrBSi alloy powder₃C₂Powder of micron Cr₃C₂Shot blasting effect of powder and nano Cr₃C₂The dispersion strengthening of the powder ensures that the prepared coating has high knot simultaneouslyHigh strength, toughness and antiwear performance. The content of FeCrBSi alloy is too low, which can cause the toughness and bonding strength of the coating to be reduced; too high a content of FeCrBSi alloy leads to a decrease in wear resistance of the coating; micron Cr₃C₂The excessive content can cause the toughness and the bonding strength of the coating to be reduced; nano Cr₃C₂Too much content results in a decrease in the wear resistance of the coating.

Compared with the prior art, the invention has the beneficial effects that: after the original powder is sprayed by adopting air fuel supersonic flame, the coating has high bonding strength, the peeling of a roller surface coating in the service process is avoided, and simultaneously, Cr₃C₂The coating adopts a micron-nanometer multi-size powder structure, so that the toughness of the coating is ensured while the hardness of the coating is improved, and the coating has low porosity, high toughness and good wear resistance. The service life of the cold roll can be effectively prolonged, the shutdown probability is reduced, and the replacement and maintenance cost of the cold roll is reduced.

Drawings

FIG. 1 shows 90FeCrBSi-5 micCr₃C₂-5nanoCr₃C₂(wt.%) surface morphology after mechanical mixing of the spray powder;

FIG. 2 is a schematic view of air-fuel supersonic flame spraying 90FeCrBSi-5 micCr₃C₂-5nanoCr₃C₂The surface appearance of the metal-based composite coating is enhanced by the nano ceramic particles;

FIG. 3 shows different nano-micron Cr₃C₂XRD of the proportional composite coating.

Detailed Description

The above and further features and advantages of the present invention are described in more detail below with reference to the accompanying drawings.

Example 1

50kg of powder is prepared; taking 45kg of FeCrBSi powder, nano-Cr and micro-Cr₃C₂5kg of powder (K)₁: micron 5kg + nanometer 0 kg; k₂: micron 3.75kg + nanometer 1.25 kg; k₃: micron 2.5kg + nanometer 2.5 kg; k₄: micron 1.25kg + nanometer 3.75 kg; k₅: micron 0kg + nano 5kg) and mixed thoroughly to obtain the coatingPowder layer, packaging; cleaning the surface of a cold-work die steel cold roll by using alcohol, checking whether the surface of the cold roll has defects such as pinholes and the like, measuring the roll shape, measuring the diameter and recording; adopting a sand blasting machine to perform sand blasting treatment, wherein the sand blasting material is 24-mesh white corundum, the angle of a spray gun is 90 degrees, and the air pressure is 5kg/cm²The distance between a spray gun and the surface of the cold roll is 500mm, and the surface roughness of the cold roll after sand blasting is required to be Ra0.2 mu m; preheating the mixed coating powder at 80 ℃ for more than 2 hours, and preparing a cold-rolling roller coating by adopting air fuel supersonic flame spraying equipment, wherein the spraying process parameters comprise a powder feeding rate of 60g/min, an oxygen flow rate of 220L/min, an air flow rate of 350L/min, a propane flow rate of 75L/min and a gun distance of 150 mm; the thickness of the coating was 0.3 mm.

FIG. 1 is a mechanically mixed 90FeCrBSi-5 micCr₃C₂-5nanoCr₃C₂The surface topography of the sprayed powder shows that the three powders are uniformly mixed. FIG. 2 is a schematic view of a supersonic flame spraying of 90FeCrBSi-5 micCr with air fuel₃C₂-5nanoCr₃C₂The surface appearance of the nano ceramic particle reinforced metal matrix composite coating can be seen from the figure, the combination of the powder is better, and the surface appearance is more uniform. XRD patterns show that the phase structures of several groups of composite coatings are similar and all comprise Fe phase and Cr phase₃C₂Phase, Cr₇C₃Phase and Cr₂O₃And (4) phase(s). Tables 1 to 3 show various nano-micron Cr₃C₂Bonding strength, fracture toughness and wear rate of the proportional composite coating.

TABLE 1 different nano-micro Cr₃C₂Bonding strength of proportional composite coating

Coating layer	K1	K2	K3	K4	K5
						Bonding strength/MPa	32.7±0.6	34.6±0.3	42.8±0.7	36.7±0.8	31.3±0.7

TABLE 2 different nano-micro Cr₃C₂Fracture toughness of proportional composite coatings

Coating layer	K1	K2	K3	K4	K5
						Fracture toughness/MPa.m1/2	2.43	2.84	2.26	2.46	2.98

TABLE 3 different nano-micro Cr₃C₂Wear rate of proportional composite coating

Coating layer	K1	K2	K3	K4	K5
						Wear rate/. times.10-14m3/N·m	8.3	7.8	5.4	7.4	7.6

As can be seen from tables 1-3, the composite coating has the best bonding strength, toughness and wear resistance when the nano-micron ratio is 50%.

Example 2

50kg of powder is prepared; taking 42.5kg of FeCrBSi powder and nano Cr₃C₂3.75kg of powder, micron Cr₃C₂3.75kg of powder, fully mixing to obtain coating powder, and packaging; cleaning the surface of a cold-work die steel cold roll by using alcohol, checking whether the surface of the cold roll has defects such as pinholes and the like, measuring the roll shape, measuring the diameter and recording; adopting a sand blasting machine to perform sand blasting treatment, wherein the sand blasting material is 24-mesh white corundum, the angle of a spray gun is 90 degrees, and the air pressure is 5kg/cm²The distance between a spray gun and the surface of the cold roll is 500mm, and the surface roughness of the cold roll after sand blasting is required to be Ra0.2 mu m; preheating the mixed coating powder at 80 ℃ for more than 2 hours, and preparing a cold-rolling roller coating by adopting air fuel supersonic flame spraying equipment, wherein the spraying process parameters comprise a powder feeding rate of 60g/min, an oxygen flow rate of 220L/min, an air flow rate of 350L/min, a propane flow rate of 75L/min and a gun distance of 150 mm; the thickness of the coating was 0.3 mm.

The foregoing is merely a preferred embodiment of the invention, which is intended to be illustrative and not limiting. It will be understood by those skilled in the art that various changes, modifications and equivalents may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.