Open fire heating furnace roller surface coating and preparation method thereof

Abstract

The invention discloses a surface coating of a furnace roller of an open fire heating furnace and a preparation method of the surface coating. The coating is prepared from the following components in percentage by mass: 50%-60% of CoNiCrAlYTa, 10%-15% of ZrB2 and 25%-35% of Y2O3. Wherein in the CoNiCrAlYTa, the content of Co is 45%-55%, the content of Ni is 15%-20%, the content of Cr is 15%-20%, the content of Al is 6%-8%, the content of Ta is 5.5%-6.7%, and the content of Y is 0.3%-0.5%; the preparation method comprises the following steps: (1) preparing coating powder; (2) processing before spraying; (3) texturing treatment; (4) preparing a coating by adopting plasma spraying; and (5) coating post-treatment. The coating provided by the invention has relatively good high-temperature anti-accumulation performance and good plasticity, toughness and thermal shock resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of furnace roller coatings, and in particular relates to a surface coating of a furnace roller of an open flame heating furnace and a preparation method thereof. Background Art

[0002] In the steel industry, the maximum operating temperature of the furnace rollers in heat treatment furnaces such as continuous annealing furnaces and normalizing furnaces reaches 1150°C. Especially in open flame heating furnaces, the local temperature of the furnace rollers even reaches over 1200°C. The surface of the furnace rollers is very easy to accumulate large areas due to high temperature oxidation and the presence of low melting point phases, thus affecting the quality of the strip.

[0003] The existing technology usually adopts spraying coating on the surface of the furnace roller to strengthen the surface of the furnace roller; the commonly used coating is mainly a mixture of CoCrAlYTa, Al2O3, and Y2O3 in a certain proportion. The operating temperature of this type of coating is generally within 1100°C; for working conditions exceeding 1100°C, the surface nodules are serious, and the coating has poor thermal shock resistance, and the coating is very likely to peel off during use. Summary of the invention

[0004] The present invention aims to provide a surface coating for a furnace roller of an open flame heating furnace and a preparation method thereof, wherein the coating is wear-resistant, resistant to high-temperature oxidation at 1250°C, and has good anti-nodulation and thermal shock properties.

[0005] To achieve the above purpose, the technical solution of the present invention is: The invention discloses a surface coating for a furnace roller of an open flame heating furnace, which is prepared from the following components in percentage by mass: CoNiCrAlYTa: 50% to 60%, ZrB2: 10% to 15%, and Y2O3: 25% to 35%.

[0006] Furthermore, in the CoNiCrAlYTa described in the present invention, the Co content is 45% to 55%, the Ni content is 15-20%, the Cr content is 15% to 20%, the Al content is 6% to 8%, the Ta content is 5.5% to 6.7%, and the Y content is 0.3% to 0.5%.

[0007] The coating of the present invention has a comprehensive melting point of 1600-1800° C., can withstand high-temperature oxidation within 1250° C., has a coating hardness of 730-900 Hv0.3, and a coating bonding strength of 60-80 Mpa.

[0008] The preparation method of the surface coating for the furnace roller of the open flame heating furnace described in the present invention is as follows: (1) Preparation of coating powder: Thoroughly mix the powders according to the mass fraction ratio.

[0009] (2) Pre - processing before spraying: The roll surface is ground by a grinding machine, and the ground roll surface is inspected. It is required that there are no defects such as lead - screw marks, scratches, pores, cracks, etc.

[0010] (3) Texturing treatment: The roll surface is sand - blasted for texturing. The sand - blasting material is 46# white fused alumina. The spray gun angle is 90±5º, the air pressure is 4 - 5 kg / cm 2 , the distance from the spray gun to the surface of the furnace roll is 500 - 600 mm. After sand - blasting the surface of the furnace roll, the surface roughness requirement is Ra4 - 6μm.

[0011] (4) Preparation of the coating by plasma spraying: A plasma spraying device is used to prepare the coating for the furnace roll. The spraying process parameters are as follows: powder feeding rate is 18 - 20 g / min, current is 600 - 650 A; the distance between the spray gun and the workpiece is 130 - 150 mm; the linear speed of the workpiece is 20 - 25 m / min; the moving speed is 5 - 6 mm / r; the coating thickness is 0.06 - 0.08 mm.

[0012] (5) Post - treatment of the coating. After spraying, the coating is subjected to a sealing treatment. The sealing material is a mixture of BN with a mass fraction of 15 - 20% and acetone with a mass fraction of 80 - 85%.

[0013] CoNiCrAlYTa has good high - temperature resistance and can improve the bonding strength between the coating and the furnace roll substrate. Among them, 15% - 20% Ni not only improves the high - temperature resistance but also enhances the plasticity and toughness of the coating. ZrB2 and Y2O3 are high - temperature - resistant ceramic phases. The melting point of ZrB2 reaches above 3000℃, and the melting point of Y2O3 reaches above 2400℃. The coating prepared from the above - mentioned components has good high - temperature anti - coking performance, good plasticity, toughness and thermal shock resistance. The comprehensive melting point of the coating is 1600 - 1800℃, which can withstand high - temperature oxidation within 1250℃. The coating hardness is 730 - 900 Hv0.3, with good wear - resistant performance. The coating bonding strength is 60 - 80 Mpa, with a high bonding strength and is not easy to peel off. Specific implementation mode

[0014] The technical solution of the present invention will be further described in detail below through examples. Example 1

[0015] A surface coating for the furnace roll of an open - flame heating furnace, and its preparation method is as follows: (1) Preparation of coating powder: The coating powder is prepared from the following components with mass percentages: CoNiCrAlYTa: 50%, ZrB2: 15%, Y2O3: 35%; among them, in the CoNiCrAlYTa, the Co content is 45%, the Ni content is 20%, the Cr content is 20%, the Al content is 8%, the Ta content is 6.7%, and the Y content is 0.3%.

[0016] (2)Pre-spray processing: The roll surface is ground using a grinding machine, and the ground roll surface is inspected for no defects such as lead marks, scratches, pores, cracks, etc.

[0017] (3)Texturing treatment: The roll surface is sandblasted for texturing. The sandblasting material is 46# white fused alumina, the spray gun angle is 85º, the air pressure is 4 kg / cm 2 , the distance from the spray gun to the surface of the furnace roll is 500 mm, and the surface roughness requirement of the furnace roll surface after sandblasting is Ra6μm; (4)Coating preparation by plasma spraying: The furnace roll coating is prepared using a plasma spraying device. The spraying process parameters are: powder feeding rate 18 g / min, current 600 A; spray gun distance 130 mm; workpiece linear speed 20 m / min; moving speed 5 mm / r; coating thickness 0.06 mm.

[0018] (5)Post-coating treatment: After spraying, the coating is subjected to a sealing treatment. The sealing material is a mixture of 15% BN and 85% acetone by mass fraction.

[0019] The coating prepared in this example has a comprehensive melting point of 1800℃, can resist high-temperature oxidation within 1250℃, the coating hardness is 900 Hv0.3, has good wear resistance, the coating bonding strength is 60 Mpa, the bonding strength is high, and it is not easy to peel off. Example 2

[0020] A surface coating for the furnace roll of an open-flame heating furnace, and its preparation method is as follows: (1)Preparation of coating powder: The coating powder is prepared from the following components by mass percentage: CoNiCrAlYTa: 55%, ZrB2: 13%, Y2O3: 32%; wherein the Co content in the CoNiCrAlYTa is 50%, the Ni content is 18%, the Cr content is 20%, the Al content is 6%, the Ta content is 5.6%, and the Y content is 0.4%.

[0021] (2)Pre-spray processing: The roll surface is ground using a grinding machine, and the ground roll surface is inspected for no defects such as lead marks, scratches, pores, cracks, etc.

[0022] (3)Texturing treatment: The roll surface is sandblasted for texturing. The sandblasting material is 46# white fused alumina, the spray gun angle is 90º, the air pressure is 4.5 kg / cm2, the distance from the spray gun to the surface of the furnace roll is 550 mm, and the surface roughness requirement of the furnace roll surface after sandblasting is Ra5μm; (4)Coating preparation by plasma spraying: The furnace roll coating is prepared using a plasma spraying device. The spraying process parameters are: powder feeding rate 19 g / min, current 630 A; spray gun distance 140 mm; workpiece linear speed 22 m / min; moving speed 5.5 mm / r; coating thickness 0.07 mm.

[0023] (5)Post-treatment of the coating: After spraying, the coating is subjected to a sealing treatment. The sealing material is a mixture of 18% BN and 82% acetone by mass fraction.

[0024] The coating prepared in this example has a comprehensive melting point of 1750 °C, can withstand high-temperature oxidation within 1250 °C, has a coating hardness of 840 Hv0.3, has good wear resistance, a coating bonding strength of 73 Mpa, a high bonding strength, and is not easily peeled off. Example 3

[0025] A surface coating for a furnace roller of an open-flame heating furnace, and its preparation method is as follows: (1)Preparation of the coating powder: The coating powder is prepared from the following components by mass percentage: CoNiCrAlYTa: 60%, ZrB2: 10%, Y2O3: 30%; wherein the Co content in the CoNiCrAlYTa is 55%, the Ni content is 15%, the Cr content is 15%, the Al content is 8%, the Ta content is 5.5%, and the Y content is 0.5%.

[0026] (2)Pre-spray processing: The roller surface is ground using a grinding machine, and the ground roller surface is inspected for no lead screw marks, scratches, pores, cracks and other defects.

[0027] (3)Texturing treatment: The roller surface is sandblasted for texturing. The sandblasting material is 46# white fused alumina, the spray gun angle is 95º, the air pressure is 5 kg / cm 2 , the distance from the spray gun to the furnace roller surface is 600 mm, and the surface roughness requirement of the furnace roller surface after sandblasting is Ra4 μm; (4)Preparation of the coating by plasma spraying: A furnace roller coating is prepared using a plasma spraying device. The spraying process parameters are: powder feeding rate 20 g / min, current 650 A; spray gun distance 150 mm; workpiece linear speed: 25 m / min; moving speed 6 mm / r; coating thickness 0.08 mm.

[0028] (5)Post-treatment of the coating. After spraying, the coating is subjected to a sealing treatment. The sealing material is a mixture of 20% BN and 80% acetone by mass fraction.

[0029] The coating prepared in this example has a coating comprehensive melting point of 1600 °C, can withstand high-temperature oxidation within 1250 °C, has a coating hardness of 730 Hv0.3, has good wear resistance, a coating bonding strength of 80 Mpa, a high bonding strength, and is not easily peeled off. Example 4

[0030] A surface coating for a furnace roller of an open-flame heating furnace, and its preparation method is as follows: (1)Preparation of coating powder: The coating powder is prepared from the following components by mass percentage: CoNiCrAlYTa: 60%, ZrB2: 15%, Y2O3: 25%; wherein the Co content in the CoNiCrAlYTa is 53%, the Ni content is 16%, the Cr content is 18%, the Al content is 7%, the Ta content is 6.5%, and the Y content is 0.5%.

[0031] (2)Pre-spray processing: The roll surface is ground by a grinding machine, and the ground roll surface is inspected for no defects such as lead screw marks, scratches, pores, cracks, etc.

[0032] (3)Texturing treatment: The roll surface is sandblasted for texturing. The sandblasting material is 46# white fused alumina, the spray gun angle is 95º, and the air pressure is 4 kg / cm 2 , the distance from the spray gun to the surface of the furnace roll is 550 mm, and the surface roughness requirement of the furnace roll surface after sandblasting is Ra5μm; (4)Preparation of the coating by plasma spraying: The furnace roll coating is prepared by a plasma spraying device. The spraying process parameters are: powder feeding rate 18 g / min, current 600 A; spray gun distance 130 mm; workpiece linear speed: 25 m / min; moving speed 6 mm / r; coating thickness 0.06 mm.

[0033] (5)Post-treatment of the coating. After spraying, the coating is sealed. The sealing material is a mixture of 16% BN and 84% acetone by mass fraction.

[0034] The comprehensive melting point of the coating prepared in this example is 1700°C, which can withstand high-temperature oxidation within 1250°C. The coating hardness is 800 Hv0.3, and it has good wear resistance. The coating bonding strength is 85 Mpa, with a high bonding strength and is not easy to peel off.

Claims

1. A surface coating for the furnace rolls of an open-flame heating furnace, characterized in that, The coating is formulated from the following components by mass percentage: CoNiCrAlYTa: 50% - 60%, ZrB2: 10% - 15%, Y2O3: 25% - 35%.

2. The surface coating of the furnace roll of an open-flame heating furnace according to claim 1, wherein In the CoNiCrAlYTa, the Co content is 45% - 55%, the Ni content is 15 - 20%, the Cr content is 15% - 20%, the Al content is 6% - 8%, the Ta content is 5.5% - 6.7%, and the Y content is 0.3% - 0.5%.

3. A surface coating for the furnace rolls of an open-flame heating furnace according to claim 1, wherein The comprehensive melting point of the coating is 1600 - 1800 °C, and it can resist high-temperature oxidation within 1250 °C. The hardness of the coating is 730 - 900 Hv0.3, and the coating bonding strength is 60 - 80 Mpa.

4. A preparation method for the surface coating of the furnace rolls of an open-flame heating furnace, characterized in that, It includes the following steps: Preparing the coating powder described in Claim 1, pre-spray processing, texturing treatment, preparing the coating by plasma spraying, and post-treatment of the coating.

5. The preparation method of the surface coating of the furnace roll of an open-flame heating furnace according to claim 4, characterized in that, The pre-spray processing: The roll surface is ground by a grinding machine, and the ground roll surface is inspected, requiring no defects such as lead marks, scratches, pores, cracks, etc.

6. The preparation method of the surface coating of the furnace roller of an open-flame heating furnace according to claim 4, characterized in that, The texturing treatment: Sandblasting is carried out on the roll surface. The sandblasting material is 46# white fused alumina, the spray gun angle is 90±5º, and the air pressure is 4-5 kg / cm 2 , the distance from the spray gun to the surface of the furnace roll is 500-600 mm, and the surface roughness Ra of the furnace roll surface after sandblasting is 4-6 μm.

7. The preparation method of the surface coating of the furnace roll of an open-flame heating furnace according to claim 4, characterized in that, The preparation of the coating by plasma spraying: The furnace roll coating is prepared by a plasma spraying device, and the spraying process parameters are: powder feeding rate 18 - 20 g / min, current 600 - 650 A; spray gun distance 130 - 150 mm; workpiece linear speed 20 - 25 m / min; moving speed 5 - 6 mm / r; coating thickness 0.06 - 0.08 mm.

8. A method for preparing a surface coating for a furnace roll of an open-flame heating furnace according to claim 4, characterized in that, The post-treatment of the coating: After spraying, the coating is subjected to a sealing treatment, and the sealing material is a mixture of 15% - 20% BN and 80% - 85% acetone by mass fraction.