Anti-oxidation device for high-temperature reduction-liquid phase sintering and use method of anti-oxidation device

Abstract

The invention relates to the technical field of material engineering, in particular to an anti-oxidation device for high-temperature reduction-liquid phase sintering and a using method of the anti-oxidation device for high-temperature reduction-liquid phase sintering. According to the device, a three-level protection system is constructed, and a deoxidation device, an oxidation sacrifice material and a reduction medium form a functional module. According to the specific implementation architecture, a deoxidation pipe filled with oxygen adsorption particles is arranged between a flow controller and a hearth, and a gradient oxidation sacrificial material is placed between a flange connector in the hearth and a workpiece to be treated; the process method comprises the following key procedures: constructing a reducing medium adsorption system in a hearth; carrying out vacuum sealing operation and then introducing a reducing atmosphere; according to the technical scheme, through the design of a three-dimensional protection structure, the loading density of the sample is improved, meanwhile, a continuous anti-oxidation environment is formed through a dynamic release mechanism of a reducing agent, and the method is particularly suitable for the working condition of long-period high-temperature reduction-liquid phase sintering treatment of the SOFC porous Fe-Cr metal supporting body.

Description

Technical Field

[0001] The present invention relates to the field of material engineering technology, and in particular to an anti-oxidation device for high-temperature reduction-liquid phase sintering and a method for using the same. Background Art

[0002] In the co-firing process for forming the porous Fe-Cr alloy metal support and electrolyte layer for solid oxide fuel cells (SOFCs), densification of the electrolyte layer typically requires sintering at temperatures exceeding 1400°C. The metal matrix, due to its inherent material properties, has an upper temperature limit. Consequently, during heat treatment experiments at temperatures above its melting point, surface components of the sample undergo oxidation reactions with oxygen in the furnace, a phenomenon that intensifies with prolonged heating time. Excessive residual oxygen in industrial high-purity reducing gas sources is a common defect. Even trace amounts of oxygen can trigger surface oxidative corrosion at sustained high temperatures. This irreversible material degradation not only alters the sample surface morphology but also leads to systematic deviations in experimental data and interrupts the experimental process. Furthermore, the metal undergoes liquid-phase sintering, which places even higher demands on its oxidation resistance.

[0003] There are many technical paths for the anti-oxidation treatment of metal materials. Specifically, it can be achieved in the following ways: first, use reducing gas to replace the air in the furnace to isolate the oxygen source, and secondly use a vacuum environment to eliminate the existence space of the oxidizing medium, or wrap the workpiece in cast iron powder for gradient heating. In addition, the protective atmosphere constructed based on the carbon thermal reduction principle can also effectively protect the metal surface. It is worth noting that different processes correspond to specific equipment requirements. The cast iron powder covering method is mostly suitable for batch heat treatment of small steel parts, while the carbon thermal reduction system requires a double crucible structure, which not only increases the size of the equipment but also limits the single processing volume. Summary of the Invention

[0004] In view of the above problems, the purpose of the present invention is to provide an anti-oxidation device for high-temperature reduction-liquid phase sintering and a method for using the same. The present invention adopts the following technical solutions: The present invention provides an antioxidant device for high-temperature reduction-liquid phase sintering, comprising a furnace shell, a furnace chamber with a heat insulation layer disposed within the furnace shell, two spaced-apart furnace plugs disposed within the furnace chamber, a sample carrier and a sacrificial oxidation material disposed between the two furnace plugs, and pipe joints connected to both ends of the furnace chamber, one of the pipe joints being connected to an air inlet pipe, and the other being connected to an air outlet pipe. The air intake pipe is connected to a reducing gas cylinder containing a mixture of hydrogen and inert gas. A flow controller, a first deoxidation device, an air intake control valve and a vacuum gauge are sequentially installed on the air intake pipe according to the gas flow direction. The gas outlet pipe is connected to the tail gas bottle, and the gas outlet control valve and the second deoxygenation device are installed on the gas outlet pipe in sequence according to the gas flow direction; the gas outlet pipe is connected to the vacuum pump through a branch pipe on the pipe section located between the gas outlet control valve and the second deoxygenation device.

[0005] Preferably, the first deoxygenation device includes a first parallel pipe and a second parallel pipe, which are connected to the air intake pipe in parallel; both the first parallel pipe and the second parallel pipe are provided with pipe end control valves; the first parallel pipe is provided with a glass tube, and the glass tube is filled with oxygen adsorption particles.

[0006] The first deoxidation device and the second deoxidation device have the same structure.

[0007] Preferably, the oxygen-absorbing particles are at least one of nano-copper oxide, nano-copper, nano-iron, nano-carbon, nano-palladium, nano-platinum, graphene, and carbon nanotubes.

[0008] Preferably, the sacrificial oxidation material is at least one of metallic titanium and carbon particles, the metallic titanium is in a thin flake or porous shape, and the carbon particles are formed by agglomeration of nano-scale carbon powder, with a particle size of 50 to 200 μm.

[0009] Preferably, the sample carrying device is made of ceramic or oxidation-resistant metal material.

[0010] Preferably, the hydrogen content of the reducing gas cylinder is 1-5%, and the rest is inert gas, and the inert gas is argon or nitrogen.

[0011] The present invention provides a method for using an anti-oxidation device for high-temperature reduction-liquid phase sintering, comprising the above-mentioned anti-oxidation device for high-temperature reduction-liquid phase sintering, and the method comprises the following steps: S1, place the metal sample on the sample table in the center area of ​​the furnace, arrange the sacrificial oxidation material, install the sealing furnace plug, and connect the air inlet and outlet pipes. Then the furnace temperature is raised to the target temperature range of 200-300 °C and maintained at a constant temperature; S2, the pipe end control valves at both ends of the first parallel pipe in the first deoxygenator are in a closed state; the pipe end control valves at both ends of the second parallel pipe in the first deoxygenator are in an open state; and the air intake control valve is in an open state; The pipe end control valves at both ends of the first parallel pipe in the second deoxidation device are in a closed state; the pipe end control valves at both ends of the second parallel pipe in the second deoxidation device are in an open state; and the gas outlet control valve is in an open state; Open the main valve of the reducing gas cylinder and start the flow controller to purge the air inlet pipe at the set flow rate for 5-15 minutes; then close the reducing gas cylinder, the flow controller, the pipe end control valves at both ends of the second parallel pipe in the first deoxygenation device, and the air inlet control valve; S3, keeping the gas outlet control valve open, the pipe end control valves at both ends of the first parallel pipe in the second deoxygenator are closed, and the pipe end control valves at both ends of the second parallel pipe in the second deoxygenator are closed; Connect the gas outlet pipe to the vacuum pump, start the vacuum pump to evacuate the furnace, and cycle the operation 1 to 5 times until the vacuum gauge indicates a value of -0.08 MPa to -0.10 MPa, then turn off the vacuum pump and close the gas outlet control valve group; S4: The pipe end control valves at both ends of the first parallel pipes in the first deoxygenator and the second deoxygenator are both in the open state, and the pipe end control valves at both ends of the second parallel pipes in the first deoxygenator and the second deoxygenator are in the closed state. Open the gas cylinder, flow controller, and air inlet control valve in sequence, and ventilate until the vacuum gauge returns to 0.01-0.02 MPa. Then, open the air outlet control valve group to keep the vacuum gauge at a slightly positive furnace pressure of 0.01-0.02 MPa to further prevent external air from infiltrating. Observe the appearance of continuous and stable bubbles in the tail gas cylinder. S5, start the heating program, the furnace temperature is 1400 ~ 1600 ℃.

[0012] Compared with the prior art, the present invention has the following beneficial technical effects: 1. Batch processing advantage: multiple samples can be loaded for simultaneous heat treatment at a time; 2. Double protection mechanism: The double physical isolation layer blocks the oxygen components in the gas and pipeline from entering the furnace. The titanium metal and carbon particles act as sacrificial oxidizing materials, effectively blocking the diffusion and migration of free oxygen to the base metal through preferential oxidation reaction. The carbon particles are formed by agglomeration of nano-scale carbon powder and will not trigger carburization reaction. 3. Economical process design: Use conventional refractory materials to construct a composite protection system, and the materials can be reused through recycling and treatment processes; 4. Parameter Adaptive Characteristics: The parameters have adaptive characteristics and are configured to dynamically adjust the operating variables based on real-time thermal parameters to establish and maintain a steady-state protection gradient. 5. Industrial application value: The standardized operating process constructed by this equipment has excellent process controllability, and its protective effectiveness and operating economy are positively coupled, showing significant prospects for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention will be further described below with reference to the accompanying drawings.

[0014] Figure 1 Schematic diagram of the structure of the anti-oxidation device for high-temperature reduction-liquid phase sintering in Example 1 of the present invention; Figure 2 The appearance and elemental analysis of Fe-Cr / YSZ without using an antioxidant device in Example 2 of the present invention; Figure 3 This is the Fe-Cr / YSZ elemental analysis and elemental analysis of the antioxidant device used in Example 2 of the present invention.

[0015] Explanation of the accompanying symbols: 1. furnace shell; 2. furnace chamber; 3. furnace plug; 4. sample carrying device; 5. sacrificial oxidizing material; 6. pipe joint; 7. reducing gas cylinder; 8. flow controller; 9. air inlet pipe; 901. air outlet pipe; 10. second deoxidation device; 11. first deoxidation device; 1101. glass tube; 1102. oxygen adsorption particles; 1103. first parallel pipe; 1104. second parallel pipe; 1105. pipe end control valve; 12. air inlet control valve; 1201. air outlet control valve; 13. vacuum gauge; 14. vacuum pump; 15. tail gas bottle; 16. temperature control instrument. DETAILED DESCRIPTION

[0016] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. Example 1

[0017] like Figure 1 As shown, this embodiment discloses an antioxidant device for high-temperature reduction-liquid phase sintering, including a furnace shell 1, a furnace chamber 2 with a heat insulation layer provided in the furnace shell 1, two spaced-apart furnace plugs 3 provided in the furnace chamber 2, a sample supporting device 4 and a sacrificial oxidation material 5 arranged between the two furnace plugs 3, and both ends of the furnace chamber 2 are connected to a pipe joint 6, which can be connected to the port of the furnace chamber 2 through a flange structure.

[0018] One of the pipe joints 6 is connected to the air intake pipe 9, which is connected to the reducing gas cylinder 7. The air intake pipe 9 is installed with a flow controller 8, a first deoxygenation device 11, an air intake control valve 12 and a vacuum gauge 13 in sequence according to the gas flow direction.

[0019] Among them, another pipe joint 6 is connected to the gas outlet pipe 901, and the gas outlet pipe 901 is connected to the tail gas bottle 15. The gas outlet pipe 901 is installed with a gas outlet control valve 1201 and a second deoxygenation device 10 in sequence according to the gas flow direction; the gas outlet pipe 901 is connected to the vacuum pump 14 through a branch pipe on the pipe section located between the gas outlet control valve 1201 and the second deoxygenation device 10.

[0020] The first deoxygenation device 11 includes a first parallel pipe 1103 and a second parallel pipe 1104, which are connected to the air intake pipe 9 in parallel. The ends of the first parallel pipe 1103 and the second parallel pipe 1104 are both provided with pipe end control valves 1105. The first parallel pipe 1103 is provided with a glass tube 1101, and the glass tube 1101 is filled with oxygen adsorption particles 1102.

[0021] In this embodiment, the first deoxidation device 11 and the second deoxidation device 10 have the same structure.

[0022] In this embodiment, the sacrificial oxidation material 5 is at least one of metallic titanium and carbon particles. The metallic titanium is in a thin sheet or porous shape. The carbon particles are formed by agglomeration of nano-scale carbon powder, and have a particle size of 50 to 200 μm.

[0023] In this embodiment, the sample carrying device 4 is made of ceramic or oxidation-resistant metal material.

[0024] Among them, the composition of reducing gas cylinder 1 is 5 vol% H2 and 95 vol% Ar. Hydrogen is used as the basic reducing medium and protective atmosphere to maintain a low oxygen partial pressure environment in the furnace and ensure the initial low oxygen state of the sintered alloy powder. Due to its wide explosion limit (LEL: 4 vol%, UEL: 75 vol%), the hydrogen concentration must be strictly limited to within 5 Vol% under high temperature conditions, and a real-time oxygen analyzer must be used to ensure that the oxygen content is less than 500 ppm. Both oxygen-adsorbed particles and metal titanium oxidation products can be recycled through reduction treatment. This embodiment also includes a temperature control instrument 16, which consists of a sensor, a controller, and an actuator. The temperature control instrument 16 can control temperature fluctuations by changing the state of the actuator (e.g., turning the heater or radiator on and off) to maintain the temperature within a set range. The specific connection and control relationship of the temperature control instrument 16 is as follows: the temperature control instrument 16 and the resistance box are placed in the same circuit and connected to a power supply; the input port of the temperature control instrument is connected to the output port of the resistance box; the temperature sensing end of the sensor (thermocouple) extends through a sealed sleeve in the furnace wall into the furnace chamber and is connected via a wire to a temperature transmitter, which transmits the output signal to the temperature control instrument; the output port of the temperature control instrument is connected to the port of the actuator (silicon molybdenum rod) to control the power input to the silicon molybdenum rod heater. The front panel of the temperature control instrument is equipped with a voltmeter, ammeter, power lock switch, start and stop push buttons, a power adjustment potentiometer, etc. for operation and monitoring.

[0025] Based on the above structure, this embodiment also discloses a method for using an anti-oxidation device for high-temperature reduction-liquid phase sintering, comprising the following steps: S1, placing a metal sample on a sample table 4 in the center area of ​​a furnace 2, sequentially arranging a sacrificial oxidation material 5, installing a sealing furnace plug 6, and connecting an air inlet pipe 9 and an air outlet pipe 901; Then, the furnace 2 is programmed to heat up to the target temperature range of 200-300 °C and maintained at a constant temperature; S2, the pipe end control valves 1105 at both ends of the first parallel pipe 1103 in the first deoxygenator 11 are in a closed state; the pipe end control valves 1105 at both ends of the second parallel pipe 1104 in the first deoxygenator 11 are in an open state; and the air intake control valve 12 is in an open state; The pipe end control valves 1105 at both ends of the first parallel pipe 1103 in the second deoxidizer 10 are in a closed state; the pipe end control valves 1105 at both ends of the second parallel pipe 1104 in the second deoxidizer 10 are in an open state; and the gas outlet control valve 1201 is in an open state; Open the main valve of the reducing gas cylinder 7 and start the flow controller 8 to purge the air intake pipe 9 at the set flow rate for 5-15 minutes; then close the reducing gas cylinder 7, the flow controller 8, the pipe end control valves 1105 at both ends of the second parallel pipe 1104 in the first deoxygenator 11, and the air intake control valve 12; S3, keep the gas outlet control valve 1201 open, the pipe end control valves 1105 at both ends of the first parallel pipe 1103 in the second deoxygenator 10 are closed, and the pipe end control valves 1105 at both ends of the second parallel pipe 1104 in the second deoxygenator 10 are closed; Connect the gas outlet pipe 901 to the vacuum pump 14, start the vacuum pump to evacuate the furnace 2, and cycle the operation 1 to 5 times until the vacuum gauge 13 indicates a value between -0.08 MPa and -0.10 MPa, then turn off the vacuum pump 14 and close the gas outlet control valve group 1201. S4, the pipe end control valves 1105 at both ends of the first parallel pipe 1103 in the first deoxygenator 11 and the second deoxygenator 10 are both in the open state, and the pipe end control valves 1105 at both ends of the second parallel pipe 1104 in the first deoxygenator 11 and the second deoxygenator 10 are in the closed state, Open the gas cylinder 7, flow controller 8, and air inlet control valve 12 in sequence, and ventilate until the vacuum gauge 13 returns to 0.01-0.02 MPa. Then, open the air outlet control valve group 1201 to maintain the vacuum gauge 13 at a slightly positive pressure state of 0.01-0.02 MPa in the furnace 2 to further prevent external air from infiltrating. Observe the appearance of continuous and stable bubbles in the tail gas cylinder 15. S6, start the heating program, the temperature of furnace 2 is 1400 ~ 1600 ℃. Example 2

[0026] like Figure 2 and 3 As shown, in this embodiment, the selected titanium metal is in the form of a thin sheet with a thickness of 0.15 mm. The selected sample carrier 4 is a corundum plate. The sample is a mixed compact of 430 stainless steel powder and YSZ powder. The selected reducing atmosphere is a 4% H2 / N2 mixture. The sample is placed in the center of the furnace 2, followed by the titanium sheet and the furnace plug. The pipe joint 6 is installed, and the temperature is raised to 200°C and then maintained. After ventilation at a flow rate of 30 ml / min for 15 minutes, the first deoxidation device 11 is connected. The flow controller 10 and the air inlet control valve 11 are closed, and the vacuum is applied three times until the vacuum gauge scale shows -0.08 MPa. The air outlet control valve 13 is closed. After the vacuum gauge scale returns to 0.01 MPa, the air inlet control valve 11 is opened and the tail gas bottle 12 is observed for the appearance of continuous and stable bubbles. The heating program is started, the temperature is raised to 1400°C, and the temperature is maintained for 4 hours. The Fe-Cr / YSZ without the antioxidant device was found to have contaminants on its surface, and the composition was determined to be iron and chromium oxides. The Fe-Cr / YSZ with the antioxidant device had a metallic luster and no oxides were formed. Example 3

[0027] As described in Example 2, the difference in this embodiment is that the selected titanium metal is in a foamy state with a circular pore size of 200 μm. The selected sample carrier is a porous cordierite plate. The sample is a mixed compact of austenitic stainless steel powder and alumina powder. The selected reducing atmosphere is a 3% H2 / N2 mixture. After the vacuum gauge scale returns to 0.01 MPa, open the gas outlet flange and observe the appearance of continuous and stable bubbles in the tail gas bottle. Start the heating program, raise the temperature to 1500°C, and keep it warm for 5 hours. Example 4

[0028] As described in Example 2, the difference in this embodiment is that the selected titanium metal is honeycomb-shaped with a pore size of 50 holes / square inch. The selected sample carrier is a porous zirconia plate. The sample is a mixed compact of Al-Mg powder and graphite powder. The selected reducing atmosphere is a 1% H2 / N2 mixture. After the vacuum gauge scale returns to 0.02 MPa, open the gas outlet flange and observe the appearance of continuous and stable bubbles in the tail gas bottle. Start the heating program, raise the temperature to 1400°C, and maintain it for 6 hours.

[0029] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. An anti-oxidation device for high-temperature reduction-liquid phase sintering, characterized by: The invention comprises a furnace shell (1), a furnace chamber (2) with a heat insulation layer provided in the furnace shell (1), two furnace plugs (3) arranged at intervals provided in the furnace chamber (2), a sample supporting device (4) and a sacrificial oxidation material (5) arranged between the two furnace plugs (3), and pipe joints (6) connected to both ends of the furnace chamber (2), one of the pipe joints (6) being connected to an air inlet pipe (9), and the other of the pipe joints (6) being connected to an air outlet pipe (901); The air intake pipe (9) is connected to the reducing gas cylinder (7), the reducing gas cylinder (7) contains a mixed gas of hydrogen and inert gas, and the air intake pipe (9) is sequentially installed with a flow controller (8), a first deoxidation device (11), an air intake control valve (12) and a vacuum gauge (13) according to the gas flow direction; The gas outlet pipe (901) is connected to the tail gas bottle (15), and a gas outlet control valve (1201) and a second deoxidation device (10) are sequentially installed on the gas outlet pipe (901) according to the gas flow direction; the gas outlet pipe (901) is connected to a vacuum pump (14) through a branch pipe on the pipe section between the gas outlet control valve (1201) and the second deoxidation device (10).

2. The anti-oxidation device for high-temperature reduction-liquid phase sintering according to claim 1, characterized in that: The first deoxygenation device (11) comprises a first parallel pipe (1103) and a second parallel pipe (1104), wherein the first parallel pipe (1103) and the second parallel pipe (1104) are connected to the air inlet pipe (9) in parallel; pipe end control valves (1105) are provided at the pipe ends of the first parallel pipe (1103) and the second parallel pipe (1104); a glass tube (1101) is provided on the first parallel pipe (1103), and the glass tube (1101) is filled with oxygen adsorption particles (1102). The first deoxidation device (11) and the second deoxidation device (10) have the same structure.

3. The anti-oxidation device for high-temperature reduction-liquid phase sintering according to claim 2, characterized in that: The oxygen adsorption particles (1102) are at least one of nano copper oxide, nano copper, nano iron, nano carbon, nano palladium, nano platinum, graphene, and carbon nanotubes.

4. The anti-oxidation device for high-temperature reduction-liquid phase sintering according to claim 1, characterized in that: The sacrificial oxidation material (5) is at least one of metallic titanium and carbon particles, the metallic titanium is in a thin sheet or porous form, and the carbon particles are formed by agglomeration of nano-scale carbon powder, with a particle size of 50 to 200 μm.

5. The anti-oxidation device for high-temperature reduction-liquid phase sintering according to claim 1, characterized in that: The sample carrying device (4) is made of ceramic or oxidation-resistant metal material.

6. The anti-oxidation device for high-temperature reduction-liquid phase sintering according to claim 1, characterized in that: The reducing gas cylinder (7) has a hydrogen content of 1-5%, and the rest is an inert gas, which is argon or nitrogen.

7. A method for using an anti-oxidation device for high-temperature reduction-liquid phase sintering, comprising the anti-oxidation device for high-temperature reduction-liquid phase sintering according to claim 2, characterized in that: The following steps are involved: S1, place the metal sample on the sample table (4) in the center area of ​​the furnace (2), arrange the sacrificial oxidation material (5), install the sealing furnace plug (6), and connect the air inlet pipe (9) and the air outlet pipe (901). Then, the furnace (2) is programmed to heat up to a target temperature range of 200-300°C and maintained at a constant temperature; S2, the pipe end control valves (1105) at both ends of the first parallel pipe (1103) in the first deoxidation device (11) are in a closed state; the pipe end control valves (1105) at both ends of the second parallel pipe (1104) in the first deoxidation device (11) are in an open state; and the air intake control valve (12) is in an open state; The pipe end control valves (1105) at both ends of the first parallel pipe (1103) in the second deoxidation device (10) are in a closed state; the pipe end control valves (1105) at both ends of the second parallel pipe (1104) in the second deoxidation device (10) are in an open state; and the gas outlet control valve (1201) is in an open state; Open the main valve of the reducing gas cylinder (7) and start the flow controller (8) to purge the air inlet pipe (9) for 5-15 minutes at the set flow rate; then close the reducing gas cylinder (7), the flow controller (8), the pipe end control valves (1105) at both ends of the second parallel pipe (1104) in the first deoxygenation device (11), and the air inlet control valve (12); S3, keeping the gas outlet control valve (1201) open, the pipe end control valves (1105) at both ends of the first parallel pipe (1103) in the second deoxygenation device (10) in a closed state, and the pipe end control valves (1105) at both ends of the second parallel pipe (1104) in the second deoxygenation device (10) in a closed state; The outlet pipe (901) is connected to the vacuum pump (14), and the vacuum pump is started to evacuate the furnace (2). The operation is repeated 1 to 5 times until the indication value of the vacuum gauge (13) reaches -0.08 MPa to -0.10 MPa. The vacuum pump (14) is then turned off. The outlet control valve group (1201) is closed. S4, the pipe end control valves (1105) at both ends of the first parallel pipe (1103) in the first deoxygenation device (11) and the second deoxygenation device (10) are both in an open state, and the pipe end control valves (1105) at both ends of the second parallel pipe (1104) in the first deoxygenation device (11) and the second deoxygenation device (10) are in a closed state. Open the gas cylinder (7), flow controller (8), and air inlet control valve (12) in sequence, and ventilate until the vacuum gauge (13) returns to 0.01-0.02 MPa. Then, open the air outlet control valve group (1201) to keep the vacuum gauge (13) at a slightly positive pressure state of 0.01-0.02 MPa in the furnace (2) to further prevent the infiltration of external air. Observe the appearance of continuous and stable bubbles in the tail gas cylinder (15); S5, start the heating program, the temperature of the furnace (2) is 1400 ~ 1600 ℃.

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