Coating for ceramic furnace roller under alternate cooling and heating working condition and spraying method of coating

Abstract

The invention discloses a coating for a ceramic furnace roller under the working condition of alternate cooling and heating and a spraying method of the coating, and belongs to the technical field of material processing. The coating sequentially comprises an LCO-17 bottom layer and an LCO-56 surface layer from the axis of the furnace roller to the outside. The spraying method comprises the following steps: step 1, pretreatment: cleaning the roller body of the furnace roller, and removing oil stains and an oxide layer; step 2, spraying a bottom layer: spraying LCO-17 powder on the surface of the roller body at the temperature of 200 DEG C or below through plasma spraying equipment to form an LCO-17 bottom layer; 3, curing treatment, wherein the bottom layer is dried, subjected to heat preservation and completely cured; step 4, spraying a surface layer: spraying LCO-56 powder on the surface of the bottom layer through plasma spraying equipment at the roller body temperature of 200 DEG C or below to form an LCO-56 surface layer; and 5, post-treatment: after natural cooling, grinding the roller surface. The invention can realize smooth transition of hardness, prolong the service life of the furnace roller, and further reduce the production cost.

Description

Technical Field

[0001] This invention belongs to the field of materials processing technology, specifically relating to a coating and spraying method for ceramic furnace rollers used in alternating hot and cold conditions. Background Technology

[0002] In the heat treatment process of strip steel production, the guide rolls (such as roll numbers 43A / 43B) at the junction of the soaking and slow cooling sections are subjected to harsh conditions for extended periods, needing to withstand drastic temperature changes in the strip steel from 780-850℃ to 480-520℃. Currently, the surface material of these guide rolls is ceramic, and the conventional spraying process uses a single LCO-56 material, resulting in a significant difference between the roll body hardness (HV320-350) and the coating hardness (HV800), with a steep hardness transition. This unreasonable hardness matching makes the roll surface coating prone to peeling off under high-temperature conditions, leading to defects such as nodules and pitting on the roll surface; these defects can then transfer to the strip steel surface, causing quality problems such as pits and roll marks. To avoid substandard product quality, companies need to replace the guide rollers every month or frequently arrange manual grinding and maintenance, which not only results in an annual replacement cost of up to 660,000 yuan (calculated at 55,000 yuan per roller, 2 rollers per replacement, and 6-8 replacements per year), but also increases equipment downtime and reduces production efficiency. This problem has not been effectively solved for a long time.

[0003] Similarly, other ceramic furnace rollers that are subjected to alternating hot and cold conditions (such as transition rollers in stainless steel production lines) also have the same problems. Summary of the Invention

[0004] Technical problem solved: To address the above-mentioned technical problems, the present invention provides a coating and spraying method for ceramic furnace rollers used in alternating hot and cold conditions, which can achieve a smooth transition in hardness, extend the service life of the furnace rollers, and thus reduce production costs.

[0005] Technical solution: A coating for a ceramic furnace roller used in alternating hot and cold conditions, comprising an LCO-17 base layer and an LCO-56 top layer from the center of the furnace roller outwards.

[0006] Preferably, the thickness of the LCO-17 substrate is 80-100 μm.

[0007] Preferably, the thickness of the LCO-56 surface layer is 120-150 μm.

[0008] Preferably, the furnace roller is used at the junction of the soaking section and the slow cooling section of the plate furnace area.

[0009] A coating spraying method for ceramic furnace rollers used in alternating hot and cold operating conditions includes the following steps: Step 1. Pretreatment: Clean the furnace roller body to remove oil and oxide layers; Step 2. Base coat: Using plasma spraying equipment, LCO-17 powder is sprayed onto the roller surface at a roller temperature of 200℃ or below to form an LCO-17 base coat. Step 3. Curing treatment: Dry and insulate the bottom layer until fully cured; Step 4. Topcoat spraying: Using plasma spraying equipment, LCO-56 powder is sprayed onto the bottom layer surface at a roller temperature of 200℃ or below to form an LCO-56 topcoat. Step 5. Post-processing: After natural cooling, polish the roller surface.

[0010] Preferably, in step 1, the standard for completing the pretreatment is: the surface roughness Ra of the furnace roller is ≤ 5 μm.

[0011] Preferably, in step 2, the parameters of the plasma spraying equipment are set as follows: current 380-420A, voltage 80-85V, spraying distance 120-150mm, and moving speed 5-8mm / s.

[0012] Preferably, in step 3, the drying temperature is 200-220℃ and the holding time is 2-3 hours.

[0013] Preferably, in step 4, the parameters of the plasma spraying equipment are set as follows: current 400-450A, voltage 85-90V, spraying distance 110-130mm, and moving speed 6-9mm / s.

[0014] Preferably, in step 5, the standard for completing the post-processing is: the roundness error of the roller surface is ≤0.05mm, and the surface roughness Ra is ≤3μm.

[0015] Beneficial effects: The core of this invention lies in the adoption of a double-layer spraying structure of "bottom layer + top layer". The bottom layer spraying involves first spraying a layer of LCO-17 material onto the surface of the ceramic roller body to form a transition bottom layer. Its hardness is between the roller body hardness (HV320-350) and the top layer hardness (HV800), which can eliminate sudden changes in hardness. The top layer spraying involves spraying conventional LCO-56 material onto its surface after the bottom layer LCO-17 has completely cured, as a functional top layer, to ensure the high temperature resistance and wear resistance of the roller surface and meet the working conditions of the general plate furnace area.

[0016] This invention has the following advantages: 1. Extended service life: The double-layer spraying structure achieves a smooth transition in hardness and avoids coating peeling. Taking the guide roller in the general plate furnace area as an example, the service life of the guide roller is extended from 1 month to 4 months, and the number of replacements per year is reduced from 6-8 times to 2-3 times. 2. Cost Reduction: Taking the guide rollers in the ordinary plate furnace area as an example, the annual replacement cost has been reduced from 660,000 yuan to 330,000 yuan, directly saving 330,000 yuan per year. At the same time, the frequency of manual grinding is reduced, lowering labor costs. 3. Improve product quality: The roller surface is free of defects such as nodules and pits, effectively avoiding pits and roller marks on the strip surface, and improving the product qualification rate; 4. Improve production efficiency: Reduce downtime for furnace roller replacement, minimize the impact of equipment maintenance on production schedule, and ensure continuous and stable operation of the production line. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the original guide roller surface; Figure 2 This is a schematic diagram of the roller surface after the improved guide roller of the present invention has been in use for 4 months. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Example 1

[0019] A coating spraying method for ceramic furnace rollers used in alternating hot and cold operating conditions includes the following steps: Step 1. Pretreatment: Clean the furnace roller body to remove impurities such as oil and oxide layer. The surface roughness Ra of the furnace roller is measured to be 4μm, which meets the spraying requirement: Ra≤5μm, thus avoiding affecting the coating adhesion.

[0020] Step 2. Base Coating: Using plasma spraying equipment, adjust the current to 400A, voltage to 82V, spraying distance to 135mm, and moving speed to 6.5mm / s to ensure uniform powder melting and a dense coating. Spray LCO-17 powder onto the roller surface to form a 90μm thick LCO-17 base coat. During the spraying process, monitor the roller temperature using an infrared thermometer to ensure it does not exceed 200℃ to prevent roller deformation.

[0021] Step 3. Curing treatment: After spraying, place the oven roller in a 210℃ oven to ensure that the bottom layer is completely cured without damaging the substrate. Keep it at this temperature for 2.5 hours to balance the curing efficiency and bonding strength, so that the bottom layer is completely cured and the bonding force between the bottom layer and the roller body is enhanced.

[0022] Step 4. Topcoat Spraying: Using plasma spraying equipment, adjust the current to 425A, voltage to 87V, spraying distance to 120mm, and moving speed to 7.5mm / s to adapt to the characteristics of LCO-56 powder and improve the high-temperature resistance and wear resistance of the topcoat. Spray LCO-56 powder onto the cured base layer surface to form an LCO-56 topcoat with a thickness of 120-150μm. During the spraying process, the roller temperature is monitored using an infrared thermometer to ensure it does not exceed 200℃.

[0023] Step 5. Post-processing: After the topcoat is applied, allow it to cool naturally to room temperature. Lightly sand the roller surface with sandpaper. The roller surface roundness error is 0.04mm and the surface roughness Ra is 2.5μm, which meets the requirements of the production line. Implementation effect

[0024] 1. Life test: Install the treated guide rollers (43A / 43B) at the junction of the soaking and slow cooling sections of the plate furnace area, record the usage time, and after 4 months of continuous operation, check the condition of the roller surface. If there are no defects such as coating peeling, nodules, or pitting, it can still be used normally. 2. Quality Inspection: 100 ordinary board products were randomly selected from the roller conveyor of this aisle and their surface quality was inspected. No products had defects such as dents or roller marks. The product qualification rate increased from 95% before the improvement to 99.5%. 3. Cost accounting: After the improvement, the number of times the guide rollers were replaced in one year was 3, and the replacement cost was 55,000 yuan / roller × 2 rolls × 3 times = 330,000 yuan, which is 330,000 yuan less than before the improvement, consistent with the expected benefits.

Claims

1. A coating for ceramic furnace rollers used in alternating hot and cold operating conditions, characterized in that, From the center of the furnace roller shaft outwards, it includes the LCO-17 bottom layer and the LCO-56 top layer.

2. The coating for a ceramic furnace roller under alternating hot and cold operating conditions according to claim 1, characterized in that, The thickness of the LCO-17 substrate is 80-100 μm.

3. The coating for a ceramic furnace roller under alternating hot and cold operating conditions according to claim 1, characterized in that, The thickness of the LCO-56 surface layer is 120-150 μm.

4. The coating for a ceramic furnace roller under alternating hot and cold operating conditions according to claim 1, characterized in that, The furnace rollers are used at the junction of the soaking and slow cooling sections in the general plate furnace area.

5. The coating spraying method for a ceramic furnace roller under alternating hot and cold operating conditions as described in claim 1, characterized in that, The steps include the following: Step 1. Pretreatment: Clean the furnace roller body to remove oil and oxide layers; Step 2. Base coat: Using plasma spraying equipment, LCO-17 powder is sprayed onto the roller surface at a roller temperature of 200℃ or below to form an LCO-17 base coat. Step 3. Curing treatment: Dry and insulate the bottom layer until fully cured; Step 4. Topcoat spraying: Using plasma spraying equipment, LCO-56 powder is sprayed onto the bottom layer surface at a roller temperature of 200℃ or below to form an LCO-56 topcoat. Step 5. Post-processing: After natural cooling, polish the roller surface.

6. A coating spraying method for a ceramic furnace roller under alternating hot and cold operating conditions according to claim 5, characterized in that, In step 1, the standard for completing the pretreatment is: the surface roughness Ra of the furnace roller is ≤5μm.

7. A coating spraying method for a ceramic furnace roller under alternating hot and cold operating conditions according to claim 5, characterized in that, In step 2, the parameters of the plasma spraying equipment are set as follows: current 380-420A, voltage 80-85V, spraying distance 120-150mm, and moving speed 5-8mm / s.

8. A coating spraying method for a ceramic furnace roller under alternating hot and cold operating conditions according to claim 5, characterized in that, In step 3, the drying temperature is 200-220℃ and the holding time is 2-3 hours.

9. A coating spraying method for a ceramic furnace roller under alternating hot and cold operating conditions according to claim 5, characterized in that, In step 4, the parameters of the plasma spraying equipment are set as follows: current 400-450A, voltage 85-90V, spraying distance 110-130mm, and moving speed 6-9mm / s.

10. A coating spraying method for a ceramic furnace roller under alternating hot and cold operating conditions according to claim 5, characterized in that, In step 5, the standard for completing the post-processing is: the roundness error of the roller surface is ≤0.05mm, and the surface roughness Ra is ≤3μm.

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