A DCB belt uniform oxidation treatment method

Abstract

The application discloses a DCB mesh belt uniform oxidation treatment method. Through stepwise temperature rising and alternate impact of oxygen-rich and oxygen-poor, a dense, uniform and not easy to fall off oxidation layer is formed on the mesh belt surface, so that the continuous downtime of equipment caused by oxidation layer falling off is shortened from 350-450 hours of the traditional method to 48-56 hours.

Description

Technical Field

[0001] This application relates to the field of metal mesh belt surface oxidation treatment technology, specifically to a method for uniform oxidation of DCB mesh belt. Background Technology

[0002] In the sintering process of DCB ceramic substrates, high-temperature resistant metal mesh belts (usually nickel-chromium alloys or iron-chromium-aluminum alloys) are required as the support and transport tools. After prolonged use in a high-temperature sintering atmosphere, an oxide layer naturally forms on the surface of the mesh belt. Traditional mesh belt oxidation treatment methods typically involve oxidizing the mesh belt in a muffle furnace at 1000°C for 36 hours with air, causing the surface to blacken and form an oxide film. This method has the following drawbacks: the oxide layer is uneven, with varying shades, making it difficult to thoroughly oxidize the interior of the mesh belt, resulting in a loose oxide layer that is easily detached; if the mesh belt is in a prolonged oxygen absorption period, repeated oxide layer detachment leads to an increase in bubbles and lumps, affecting the yield of DCB products; and the mesh belt requires frequent shutdowns for replacement or reprocessing due to oxide layer issues, resulting in downtime of 350-450 hours (approximately 30-35 shifts), impacting production efficiency.

[0003] Therefore, this application is submitted. Summary of the Invention

[0004] The purpose of this invention is to provide a method for uniform oxidation of DCB conveyor belts. By step-by-step heating and alternating oxygen-rich and oxygen-deficient impacts, a dense, uniform, and non-detachable oxide layer is formed on the surface of the conveyor belt, thereby reducing the continuous downtime of equipment caused by oxide layer detachment from 350-450 hours in the traditional method to 48-56 hours.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following solution: A method for uniform oxidation of DCB conveyor belt involves passing the conveyor belt through multiple temperature zones in a tunnel furnace, including at least six constant temperature zones. Within each constant temperature zone, the conveyor belt undergoes four stages with increasing temperature, and each temperature stage is treated with a corresponding atmosphere. By stepwise temperature increases combined with alternating oxygen-rich and oxygen-poor impacts, a dense, uniform, and non-detachable oxide layer is formed on the surface of the conveyor belt.

[0006] Furthermore, the first stage is only an oxygen-enriched atmosphere, while the second, third, and fourth stages are all characterized by first an oxygen-enriched atmosphere and then an oxygen-deficient atmosphere.

[0007] This invention employs six constant temperature zones, each with four independently set temperature stages, wherein the second, third, and fourth stages are first oxygen-enriched and then oxygen-depleted.

[0008] The actual working process of a DCB tunnel furnace involves the conveyor belt moving from a low-temperature zone to a high-temperature zone, undergoing a gradual temperature increase. This stepped heating is replicated beforehand in each isothermal zone, allowing the conveyor belt to adapt to actual operating conditions in advance, resulting in an oxide layer structure that better matches the thermal shock environment of the tunnel furnace. Furthermore, the oxidation rate is slower in the low-temperature section (first stage), forming a thinner initial oxide film as a preparatory layer for subsequent oxidation. As the temperature rises, the oxidation rate accelerates; if directly exposed to the highest temperature, the oxide layer would grow too quickly and have a loose structure. A transition through intermediate temperatures allows the oxide layer to gradually densify, avoiding internal stress caused by sudden temperature changes.

[0009] The oxygen-enriched atmosphere in the second, third, and fourth stages provides a sufficient oxygen source, causing the metal on the conveyor belt surface to oxidize rapidly, forming an oxide layer, primarily for thickening the oxide layer. When the atmosphere switches to oxygen-deficient (extremely low oxygen concentration), the external oxygen supply is cut off, and the oxidation reaction essentially stops. At this time, the already formed oxide layer undergoes densification and stress release, while the unoxidized interface between the oxide layer and the metal substrate diffuses and bonds, increasing the bonding strength. Alternating between oxygen-enriched and oxygen-deficient treatments simulates the actual atmospheric fluctuations of a tunnel furnace, allowing the conveyor belt to adapt in advance to the instantaneous oxygen-deficient or oxygen-enriched conditions in the future working environment, thus reducing the likelihood of detachment during actual use.

[0010] Furthermore, an oxygen-deficient atmosphere is achieved by introducing nitrogen or other inert gases.

[0011] Furthermore, the four stages include: First stage: Oxidation treatment is carried out in an oxygen-rich atmosphere for a first preset time within a first temperature range; Second stage: Within a second temperature range higher than the first temperature range, oxidation treatment is carried out in an oxygen-rich atmosphere for a second preset duration, and then in an oxygen-deficient atmosphere for a third preset duration. The third stage: Within a third temperature range higher than the second temperature range, oxidation treatment is carried out in an oxygen-rich atmosphere for a fourth preset duration, and then in an oxygen-deficient atmosphere for a fifth preset duration. Fourth stage: Within the fourth temperature range, which is higher than the third temperature range, oxidation treatment is carried out in an oxygen-rich atmosphere for a sixth preset duration, and then in an oxygen-deficient atmosphere for a seventh preset duration.

[0012] Furthermore, the oxygen-enriched atmosphere is compressed air with a flow rate of 15~25L / min; the oxygen-deficient atmosphere is a low-oxygen atmosphere achieved by filling with nitrogen, wherein the oxygen concentration is less than 300ppm.

[0013] Furthermore, the first temperature range is 500~700℃, the second temperature range is 700~900℃, the third temperature range is 900~1100℃, and the fourth temperature range is 1100~1300℃.

[0014] Furthermore, the first preset duration is 30-60 hours, the second and third preset durations are both 40-70 hours, the fourth preset duration is 60-80 hours, the fifth preset duration is 40-70 hours, the sixth preset duration is 60-80 hours, and the seventh preset duration is 40-70 hours.

[0015] Furthermore, the tunnel furnace is also provided with a heating zone located before the constant temperature zone and a cooling zone located after the constant temperature zone; the temperature range of the heating zone and the cooling zone is 400~700℃.

[0016] Furthermore, both the heating zone and the cooling zone are vented with an oxygen-rich atmosphere.

[0017] Furthermore, the method reduces the continuous downtime of the DCB conveyor belt due to oxide layer peeling from 350-450 hours to 48-56 hours, and the oxide layer of the conveyor belt is uniform in color and does not peel off.

[0018] The beneficial effects of this invention are as follows: This invention forms a highly dense and uniform oxide layer on the surface of the conveyor belt by stepwise heating in each constant temperature zone, combined with alternating oxygen-rich and oxygen-deficient impacts. The oxide layer does not fall off under the high and low temperature impacts of the subsequent simulated sintering atmosphere; this avoids contamination of the DCB substrate by oxide skin shedding, improves product yield, and shortens equipment downtime to only 48-56 hours, thus improving production efficiency. Attached Figure Description

[0019] Figure 1 This is a process flow diagram of the present invention; Figure 2 This is a photograph of the actual mesh belt obtained after processing according to the present invention; Figure 3 This is a photograph of the actual mesh belt obtained using traditional methods. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention.

[0022] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0023] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0024] Example 1 Reference Figure 1 A tunnel furnace with ten temperature zones is used, consisting of two heating zones (temperature 400~700℃, each 250mm long), six constant temperature zones (each 200mm long), and two cooling zones (temperature 400~700℃, each 250mm long). The conveyor belt to be processed is passed through the tunnel furnace at a linear speed of 0.5m / min.

[0025] Each constant temperature zone is divided into four temperature stages along the direction of the conveyor belt, according to the increasing temperature: First stage: Temperature 400℃, compressed air (20L / min) is introduced for oxygen-enriched oxidation for 60 hours.

[0026] Second stage: Temperature 700℃, first introduce compressed air (20L / min) for oxygen-enriched oxidation for 70 hours, then switch to nitrogen (oxygen concentration <300ppm) for oxygen-deficient treatment for 70 hours.

[0027] The third stage: at a temperature of 900℃, compressed air (20L / min) was first introduced for oxygen-enriched oxidation for 80 hours, and then the process was switched to nitrogen-deficient treatment for 70 hours.

[0028] Fourth stage: Temperature 1100℃, first introduce compressed air (20L / min) for oxygen-enriched oxidation for 80 hours, then switch to nitrogen-deficient treatment for 70 hours.

[0029] Repeat the above four temperature stages five more times, with the oxygen atmosphere in the heating and cooling zones being consistent with the oxygen-enriched atmosphere.

[0030] After processing, a uniform black oxide layer is formed on the surface of the conveyor belt (see reference). Figure 2 The mesh belt showed no signs of peeling when tested with adhesive tape. When used in a DCB sintering furnace, the belt ran continuously for 800 hours without any oxide layer peeling. The downtime due to mesh belt oxidation was 48 hours (4 shifts), significantly less than the 420 hours (35 shifts) of the traditional process.

[0031] Example 2 It is basically the same as Example 1, except that: Phase 1: Temperature 600℃, Time 45 hours; Second stage: Temperature 750℃, oxygen-rich for 55 hours, oxygen-deficient for 55 hours; Phase 3: Temperature 1000℃, oxygen-rich for 70 hours, oxygen-deficient for 55 hours; Phase 4: Temperature 1200℃, oxygen-rich for 70 hours, oxygen-deficient for 55 hours.

[0032] Compressed air at 15L / min resulted in a uniform oxide layer on the treated mesh belt with no peeling, and the equipment was shut down for 52 hours.

[0033] Example 3 It is basically the same as Example 1, except that: Phase 1: Temperature 700℃, Time 30 hours; Second stage: Temperature 900℃, oxygen-rich for 40 hours, oxygen-deficient for 40 hours; Phase 3: Temperature 1100℃, oxygen-rich for 60 hours, oxygen-deficient for 40 hours; Phase 4: Temperature 1200℃, oxygen-rich for 60 hours, oxygen-deficient for 40 hours.

[0034] Compressed air at 25L / min, the treated mesh belt has a uniform oxide layer without peeling, and the equipment downtime is 56 hours.

[0035] Comparative Example 1 Air was introduced into the muffle furnace, and the oxidation treatment was carried out at a constant temperature of 1000℃ for 36 hours without step heating or oxygen-deficient treatment. As a result, the oxide layer on the conveyor belt surface exhibited varying shades of color (see reference). Figure 3 (The area within the box) shows partial oxide scale peeling. Significant peeling occurred after 200 hours of operation, and the equipment was shut down for 420 hours.

[0036] Comparative Example 2 The process was essentially the same as in Example 1, except that only oxygen-enriched oxidation was performed in all four stages of each constant-temperature zone, without any oxygen-deficient treatment. As a result, the oxide layer on the conveyor belt was not dense enough and began to peel off after 350 hours of operation, resulting in a downtime of 256 hours.

[0037] Comparative Example 3 The results were largely the same as in Example 1, except that the oxygen-enriched atmosphere flow rate in the four stages of each constant temperature zone was less than 15 L / min or greater than 25 L / min of compressed air. Otherwise, the results were the same as in Example 1. The oxide layer on the conveyor belt was found to be insufficiently dense, and began to peel off after 389 or 354 hours of operation, with a downtime of 220 or 269 hours.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for uniform oxidation of DCB mesh belt, characterized in that, The mesh belt is sequentially processed through multiple temperature zones in a tunnel furnace, including at least six constant temperature zones. Within each constant temperature zone, the mesh belt passes through four stages with increasing temperature, and each temperature stage is subjected to corresponding atmosphere treatment. By stepwise temperature increases combined with alternating oxygen-rich and oxygen-poor impacts, a dense, uniform, and non-detachable oxide layer is formed on the surface of the mesh belt.

2. The method for uniform oxidation of DCB mesh belt according to claim 1, characterized in that, The first stage is only an oxygen-enriched atmosphere, while the second, third, and fourth stages are all characterized by first an oxygen-enriched atmosphere and then an oxygen-depleted atmosphere.

3. The method for uniform oxidation of DCB mesh belt according to claim 1, characterized in that, An oxygen-deficient atmosphere is achieved by introducing nitrogen or other inert gases.

4. The method for uniform oxidation of DCB mesh belt according to claim 1, characterized in that, The four stages include: First stage: Oxidation treatment is carried out in an oxygen-rich atmosphere for a first preset time within a first temperature range; Second stage: Within a second temperature range higher than the first temperature range, oxidation treatment is carried out in an oxygen-rich atmosphere for a second preset duration, and then in an oxygen-deficient atmosphere for a third preset duration. The third stage: Within a third temperature range higher than the second temperature range, oxidation treatment is carried out in an oxygen-rich atmosphere for a fourth preset duration, and then in an oxygen-deficient atmosphere for a fifth preset duration. Fourth stage: Within the fourth temperature range, which is higher than the third temperature range, oxidation treatment is carried out in an oxygen-rich atmosphere for a sixth preset duration, and then in an oxygen-deficient atmosphere for a seventh preset duration.

5. The method for uniform oxidation of DCB mesh belt according to claim 1, characterized in that, The oxygen-enriched atmosphere is made of compressed air with a flow rate of 15~25L / min; the oxygen-deficient atmosphere is a low-oxygen atmosphere achieved by filling with nitrogen, in which the oxygen concentration is less than 300ppm.

6. The method for uniform oxidation of DCB mesh belt according to claim 4, characterized in that, The first temperature range is 500~700℃, the second temperature range is 700~900℃, the third temperature range is 900~1100℃, and the fourth temperature range is 1100~1300℃.

7. The method for uniform oxidation of DCB mesh belt according to claim 4, characterized in that, The first preset duration is 30-60 hours, the second and third preset durations are both 40-70 hours, the fourth preset duration is 60-80 hours, the fifth preset duration is 40-70 hours, the sixth preset duration is 60-80 hours, and the seventh preset duration is 40-70 hours.

8. The method for uniform oxidation of DCB mesh belt according to claim 1, characterized in that, The tunnel furnace is also equipped with a heating zone before the constant temperature zone and a cooling zone after the constant temperature zone; the temperature range of the heating zone and the cooling zone is 400~700℃.

9. The method for uniform oxidation of DCB mesh belt according to claim 8, characterized in that, Both the heating and cooling zones are vented with an oxygen-rich atmosphere.

10. The method for uniform oxidation of DCB mesh belt according to claim 1, characterized in that, The method reduces the continuous downtime of DCB conveyor belts caused by oxide layer peeling from 350-450 hours to 48-56 hours, and ensures that the oxide layer of the conveyor belt is uniform in color and does not peel off.

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