A furnace bottom roller thermal spray material for preventing sticking of steel in a continuous annealing furnace

Abstract

A kind of furnace bottom roller thermal spraying material for preventing steel sticking in continuous annealing furnace belongs to the technical field of thermal spraying powder, and includes the following components: NiCoCrAlY, nano Y2O3, micron-grade alumina and chromium boride ceramic, wherein NiCoCrAlY accounts for 55-70% of total weight, nano Y2O3 accounts for 0.3-1.0% of total weight, micron-grade alumina accounts for 15-25% of total weight, and chromium boride ceramic accounts for 8-25% of total weight.By adding nano Y2O3 in the alloy, the loss and segregation of Y content during spraying process are improved, and the service life of the coating is improved.

Description

Technical Field

[0001] This invention belongs to the field of thermal spraying powder technology, and particularly relates to a furnace bottom roller thermal spraying material for preventing steel from sticking in a continuous annealing furnace. Background Technology

[0002] In a continuous annealing furnace, steel plates are transported by the friction of the furnace bottom rollers. The hardness of steel materials at high temperatures decreases, and the surface is easily worn. As iron oxide or manganese oxide from the surrounding environment transfers to the surface of the furnace bottom rollers, the accumulation of these oxides will damage the steel surface. In particular, as the processing speed of steel plates increases and the transport speed of steel plates accelerates, the damage becomes more severe.

[0003] Applying a thermal spray coating to the surface of the furnace bottom roll effectively prevents oxide buildup, improves the surface quality of the steel plate, and extends the service life of the furnace bottom roll. Commonly used spraying materials include NiCrAlY or NiCoCrAlY, as well as combinations of different oxides and boride ceramics. MCrAlY provides sufficient bonding strength and thermal shock resistance to ensure that the oxide and boride ceramics remain firmly embedded in the coating. During use, the quality of the oxide film on the coating surface is crucial for anti-adhesion performance. During thermal spraying, the alloy powder undergoes heating and melting followed by rapid solidification on the substrate. Therefore, the Y content in the NiCoCrAlY alloy undergoes two changes during spraying: burn-off during spraying and segregation of Y during alloy solidification. Burn-off reduces the Y content in the alloy system, while segregation during solidification leads to localized Y reduction. Both of these factors deteriorate the oxide film performance on the alloy surface, resulting in a furnace bottom roll service life generally less than 9 months.

[0004] In addition, if oxide ceramic particles detach from the coating, it will cause coating defects, which will lead to the enrichment of oxides on the surface of the steel plate on the coating surface, prematurely causing oxide accumulation and reducing the service life of the coating. Summary of the Invention

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a furnace bottom roller thermal spraying material for preventing steel from sticking in a continuous annealing furnace. By adding nano Y2O3 to the alloy, the loss and segregation of Y content during the spraying process are improved, thereby increasing the service life of the coating.

[0006] To achieve the above objectives, the main technical solutions adopted by the present invention include: A furnace bottom roller thermal spraying material for preventing steel from sticking in a continuous annealing furnace comprises the following components: NiCoCrAlY, nano Y2O3, micron-sized alumina, and chromium boride ceramic, wherein NiCoCrAlY accounts for 55-70% of the total weight, nano Y2O3 accounts for 0.3-1.0% of the total weight, micron-sized alumina accounts for 15-25% of the total weight, and chromium boride ceramic accounts for 8-25% of the total weight.

[0007] Furthermore, the particle size of NiCoCrAlY is 5-20 micrometers; the particle size of nano Y2O3 is 5-50 nanometers; the particle size of micron-sized alumina is 5-10 micrometers; and the particle size of chromium boride ceramic powder is 1-10 micrometers.

[0008] Furthermore, the preparation method of the furnace bottom roller thermal spraying material is agglomeration granulation method, spray granulation-sintering method, sintering crushing method or other powder forming method.

[0009] The coating preparation method using the aforementioned furnace bottom roller thermal spraying material includes supersonic flame spraying, explosive spraying, plasma spraying, and flame spraying.

[0010] The beneficial effects of this invention are: As mentioned earlier, during thermal spraying, the Y content in the alloy powder decreases and its distribution becomes uneven. Adding nano-Y2O3 to the alloy can effectively improve the loss and segregation of Y content during spraying, thereby improving the structure of the oxide film on the NiCoCrAlY surface, making the oxide film more complete and continuous, and thus improving the high-temperature oxidation resistance and anti-adhesion properties of the coating. Simultaneously, the nano-Y2O3 present in the coating can also improve the bonding between the micron-sized alumina and the coating itself. Nano-Y2O3 forms a good interfacial bond with NiCoCrAlY, ensuring contact between the micron-sized alumina and the coating, preventing alumina from detaching during use. Using the composite powder prepared in this invention as raw material, the coating prepared by supersonic flame spraying can achieve a service life of up to 12 months, which is more than 1.3 times that of previous methods. Attached Figure Description

[0011] Figure 1 The image shows the surface morphology of the furnace bottom roller thermal spray material of the present invention prepared by spray drying-sintering method in Example 1. Figure 2 The surface morphology of the coating prepared in Example 1 after 12 months of use; Figure 3 The surface morphology of the furnace bottom roller after 9 months of use without coating; Figure 4 The surface morphology of the coating prepared in Example 2 after 15 months of use; Figure 5 The surface morphology of the coating prepared in Example 3 after 12 months of use is shown in the image. Detailed Implementation

[0012] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0013] This invention provides a furnace bottom roller thermal spraying material for preventing steel from sticking in a continuous annealing furnace, comprising the following components: NiCoCrAlY, nano Y2O3, micron-sized alumina, and chromium boride ceramic, wherein NiCoCrAlY accounts for 55-70% of the total weight, nano Y2O3 accounts for 0.3-1.0% of the total weight, micron-sized alumina accounts for 15-25% of the total weight, and chromium boride ceramic accounts for 8-25% of the total weight.

[0014] The particle size of NiCoCrAlY is 5-20 micrometers; the particle size of nano Y2O3 is 5-50 nanometers; the particle size of micron-sized alumina is 5-10 micrometers; and the particle size of chromium boride ceramic powder is 1-10 micrometers.

[0015] The preparation method of the furnace bottom roller thermal spraying material is agglomeration granulation method, spray granulation-sintering method, sintering crushing method or other powder forming method.

[0016] The coating preparation method using the aforementioned furnace bottom roller thermal spraying material includes supersonic flame spraying, explosive spraying, plasma spraying, and flame spraying.

[0017] Example 1 Selected powder raw materials: NiCoCrAlY with a particle size of 5~20 micrometers, 55kg; nano Y2O3 with a particle size of 20 nanometers, 0.3kg; micron-sized alumina with a particle size of 10 micrometers, 25kg; chromium boride ceramic powder with a particle size of 3 micrometers, 19.7kg.

[0018] All the above powders were mixed and ball-milled for 24 hours. Binders and defoamers were added, and the mixture was spray-dried and vacuum sintered. After sieving, a powder of 15-45 micrometers was obtained. Supersonic flame spraying was used to prepare a coating with a thickness of approximately 0.3 mm. The substrate was a ZG40Cr28Ni48W5 furnace bottom roller, and the service life could reach over 12 months. Figure 2 The image shows the surface morphology of the coating prepared in Example 1 after 12 months of use. The surface of the furnace roller is basically intact, and the diameter of the furnace roller remains basically unchanged. Figure 3 The image shows the surface morphology of the furnace rollers after 9 months of use without coating. The surface is severely worn, and the roller diameter has decreased by more than 2mm. The comparison clearly shows that applying the coating effectively extends the service life of the furnace bottom rollers.

[0019] Example 2 Selected powder raw materials: NiCoCrAlY with a particle size of 5-20 micrometers, 70 kg; nano Y2O3 with a particle size of 5 nanometers, 1.0 kg; micron-sized alumina with a particle size of 10 micrometers, 21 kg; chromium boride ceramic powder with a particle size of 3 micrometers, 8 kg. All the above powders are mixed and ball-milled for 24 hours. Binders and defoamers are added, and spray drying and vacuum sintering are used. After sieving, a powder with a particle size of 15-45 micrometers is obtained. Explosive spraying is used to prepare a coating with a thickness of approximately 0.4 mm. The substrate is a ZG40Cr28Ni48W5 furnace bottom roller, and the service life can reach more than 15 months. Figure 4 The image shows the surface morphology of the coating prepared in Example 2 after 15 months of use. The surface of the furnace roller is basically intact, and the diameter of the furnace roller remains basically unchanged.

[0020] Example 3 Selected powder raw materials: NiCoCrAlY with a particle size of 5-20 micrometers, 60 kg; nano Y2O3 with a particle size of 10 nanometers, 0.5 kg; micron-sized alumina with a particle size of 8 micrometers, 15 kg; chromium boride ceramic powder with a particle size of 3 micrometers, 24.5 kg. All the above powders are mixed and ball-milled for 24 hours. Binders and defoamers are added, and spray drying and vacuum sintering are used. After sieving, powder with a particle size of 15-45 micrometers is obtained. Supersonic flame spraying is used to prepare a coating with a thickness of approximately 0.25 mm. The substrate is a ZG40Cr28Ni48W5 furnace bottom roller, and the service life can reach more than 12 months. Figure 5 The image shows the surface morphology of the coating prepared in Example 3 after 12 months of use. The surface of the furnace roller is basically intact, and the diameter of the furnace roller remains basically unchanged.

[0021] This invention effectively reduces the loss and segregation of Y content during the spraying process by adding nano-Y2O3 to the alloy, thereby improving the structure of the oxide film on the NiCoCrAlY surface, making the oxide film more complete and continuous, and thus improving the high-temperature oxidation resistance and anti-adhesion properties of the coating. Simultaneously, the nano-Y2O3 in the coating can also improve the bonding between the micron-sized alumina and the coating itself. The nano-Y2O3 forms a good interfacial bond with NiCoCrAlY, ensuring contact between the micron-sized alumina and the coating, preventing alumina from detaching during use.

[0022] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any modifications, alterations, substitutions, and variations made by those skilled in the art to the above embodiments are within the scope of the present invention.

Claims

1. A furnace bottom roller thermal spraying material for preventing steel adhesion in a continuous annealing furnace, characterized in that, The product comprises the following components: NiCoCrAlY, nano-Y2O3, micron-sized alumina, and chromium boride ceramic, wherein NiCoCrAlY accounts for 55-70% of the total weight, nano-Y2O3 accounts for 0.3-1.0% of the total weight, micron-sized alumina accounts for 15-25% of the total weight, and chromium boride ceramic accounts for 8-25% of the total weight; the particle size of NiCoCrAlY is 5-20 microns; the particle size of nano-Y2O3 is 5-50 nanometers; the particle size of micron-sized alumina is 5-10 microns; and the particle size of chromium boride ceramic powder is 1-10 microns.

2. The furnace bottom roller thermal spraying material for preventing steel adhesion in a continuous annealing furnace according to claim 1, characterized in that: The preparation method of the furnace bottom roller thermal spray material is one of the following: agglomeration granulation method, spray granulation-sintering method, and sintering crushing method.

3. A coating preparation method using the furnace bottom roller thermal spraying material according to any one of claims 1-2, characterized in that: The coating preparation methods include explosive spraying, plasma spraying, and flame spraying.

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