Preparation method of ion flame detector metal tube oxidation-resistant and corrosion-resistant insulating sleeve

Abstract

This invention discloses a method for preparing an oxidation- and corrosion-resistant insulating sheath for an ion flame detector metal tube, comprising the following steps: winding alumina fiber cloth around a graphite rod to obtain an alumina fiber cloth preform; depositing a silicon carbide interface layer on the alumina fiber cloth preform using a CVD process to obtain an alumina fiber cloth preform with a silicon carbide interface layer, and then removing the graphite rod; immersing the alumina fiber cloth preform with the silicon carbide interface layer in an alumina sol-silica powder slurry, and then drying it to obtain a particle-fiber reinforced alumina ceramic matrix composite material green body; subjecting the green body to high-temperature sintering to obtain a particle-fiber reinforced alumina ceramic matrix composite material; repeating the immersion and sintering process until the mass of the composite material increases by less than 5 wt% compared to the previous sintering. The composite material sheath prepared by this invention has multiple characteristics such as low density, corrosion resistance, high-temperature oxidation resistance, high toughness, and good insulation.

Description

Technical Field

[0001] This invention belongs to the field of anti-corrosion materials and preparation technology for metal tubes, specifically relating to a method for preparing an oxidation-resistant and corrosion-resistant insulating sheath for an ion flame detector metal tube. Background Technology

[0002] As is well known, ion flame detectors are crucial components of aerospace engines. They detect the concentration of ions produced by the flame to determine flame characteristics and thus monitor engine operation. Currently, there are many types of ion flame detectors in use, but their key components are essentially the same, including a sheath, probe, center electrode, and press-fitted ceramic ring. The sheath is one of the most important components, its main function being to protect the internal components of the ion flame detector, reduce the influence of the external environment, minimize interference, and improve detection accuracy. In addition, the sheath should also have heat insulation and dustproof functions, helping to ensure the normal operation of the ion flame detector and extend its service life. Therefore, improving the relevant performance of the sheath is key to improving the reliability of aerospace engines.

[0003] During the operation of aerospace engines, the presence of aviation oil creates a highly corrosive internal environment. Furthermore, the continuous combustion process results in a high-temperature oxidizing reaction environment inside the engine. The ion flame detector is located inside the engine, and its sheathing material needs to possess high resistance to high-temperature oxidation and corrosion. In addition, to prevent electrical short circuits and ensure safe operation, the sheathing material also needs to have good insulation properties.

[0004] Currently, the most widely used cladding materials are high-temperature alloys. However, high-temperature alloys have high density and are prone to oxidation, both of which affect the performance of the cladding materials. In contrast, although ceramic materials have good oxidation resistance, corrosion resistance, and insulation properties, their toughness is relatively low. Therefore, neither high-temperature alloys nor pure ceramic materials are suitable for cladding fabrication. Thus, it is necessary to develop a method for preparing an oxidation-resistant, corrosion-resistant, and insulating cladding for the metal tube of an ion flame detector to meet the multiple requirements of oxidation resistance, corrosion resistance, insulation, and high toughness for ion flame detector cladding.

[0005] Chinese patent application CN110159842A discloses a multi-layer composite fuel pipe, comprising an outermost wear-resistant layer and at least one barrier layer, with an adhesive layer between each layer. The barrier layer consists of two layers: an ethylene / vinyl alcohol copolymer and poly(m-phenylene adipamide), respectively. The innermost wear-resistant layer is modified to become a conductive layer, and its inner wall is coated with a conductive coating. The wear-resistant layer is made of polyamide. The adhesive layer is made of adhesive resin. The wear-resistant layer has a thickness of 0.1-0.5 mm, the adhesive layer has a thickness of 0.05-0.15 mm, the barrier layer has a thickness of 0.05-0.5 mm, and the total wall thickness is 1.1±0.15-1.6±0.2 mm. This technical solution tends to design a fuel pipe with good barrier and conductivity properties. Although the designed fuel pipe is resistant to chemical corrosion, its structure is relatively complex. The more complex the structure, the more difficult the manufacturing process and the greater the error. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a method for preparing an oxidation-resistant and corrosion-resistant insulating sheath for an ion flame detector metal tube, comprising the following steps in sequence:

[0007] Step 1: Prepare alumina fiber cloth, alumina fiber bundles, alumina sol, silica powder, and graphite rods according to the design requirements; at the same time, prepare alumina sol-silica powder slurry according to the design requirements.

[0008] Step 2: Pre-treat the alumina fiber cloth according to the design requirements to remove the organic adhesive on the alumina fiber cloth;

[0009] Step 3: Lay the pretreated alumina fiber cloth flat on a horizontal surface, place a graphite rod at one end of the alumina fiber cloth, and roll the graphite rod from one end of the alumina fiber cloth to the other end to make the alumina fiber cloth wrap around the graphite rod, thus obtaining a tubular alumina fiber cloth preform.

[0010] Step 4: Use alumina fiber bundles to spirally wind around the outside of the tubular alumina fiber cloth preform from one end to the other, and at the same time use high-temperature adhesive to fix the two ends of the alumina fiber bundles to the two ends of the graphite rod respectively.

[0011] Step 5: Using the chemical vapor deposition process of the MTS-Ar-H2 reaction system, a silicon carbide interface layer is deposited on the tubular alumina fiber cloth preform, so that the outer surface of each alumina fiber is coated with a silicon carbide interface layer, thereby obtaining an alumina fiber cloth preform with a silicon carbide interface layer deposited on it.

[0012] Step 6: After the silicon carbide interface layer is deposited, the alumina fiber cloth wrapped around the graphite rod is hardened and fixed, and the graphite rod is extracted from the alumina fiber cloth preform with the silicon carbide interface layer deposited.

[0013] Step 7: Immerse the alumina fiber cloth preform with the silicon carbide interface layer in the alumina sol-silica powder slurry. After immersion, remove the alumina fiber cloth preform from the slurry and dry it. After drying, a particle-fiber reinforced alumina ceramic matrix composite preform is obtained.

[0014] Step 8: Place the particle-fiber reinforced alumina ceramic matrix composite green body into a muffle furnace for high-temperature sintering to obtain the particle-fiber reinforced alumina ceramic matrix composite.

[0015] Step 9: Weigh the particle-fiber reinforced alumina ceramic matrix composite material after high-temperature sintering and record the weighing data; repeat steps 7 and 8 until the mass of the particle-fiber reinforced alumina ceramic matrix composite material increases by less than 5 wt% compared to the previous mass, and use it as the sheath for the metal tube of the ion flame detector.

[0016] Preferably, in step one, the alumina fiber cloth is woven from transverse alumina fiber bundles and longitudinal alumina fiber bundles. The width of the transverse alumina fiber bundle is 0.8-1.4 mm, the width of the longitudinal alumina fiber bundle is 0.8-1.4 mm, and the thickness of the alumina fiber cloth is 0.2-0.4 mm. Each alumina fiber bundle consists of 500-2000 alumina fiber filaments. The alumina sol has a pH value of 3.0-5.0 and a density of 1.2-1.3 g / cm³. 3 The viscosity does not exceed 15 C·P, the alumina content in the alumina sol is 35-45 wt%, the particle size of the alumina is 1-10 nm, and the particle size of the silica powder is 10-500 nm.

[0017] In any of the above schemes, it is preferred that, in step one, the method for preparing the alumina sol-silica powder slurry is as follows: silica powder is added to the alumina sol and stirred for 1-3 hours to ensure that the silica powder is uniformly dispersed in the alumina sol; wherein the silica powder accounts for 10-30 wt% of the slurry by mass, and the alumina sol accounts for 70-90 wt% of the slurry by mass.

[0018] In any of the above schemes, it is preferred that, in step two, the pretreatment process of the alumina fiber cloth is as follows: the alumina fiber cloth is placed in a muffle furnace and heated from room temperature to 400-700℃ at a heating rate of 6-12℃ / min, kept at that temperature for 1-3 hours, and then naturally cooled to room temperature.

[0019] In any of the above embodiments, it is preferred that, in step three, the alumina fiber cloth is wound 5-50 layers on the graphite rod.

[0020] In any of the above schemes, preferably, in step five, the chemical vapor deposition process for the tubular alumina fiber cloth preform is as follows: the tubular alumina fiber cloth preform is placed in a chemical vapor deposition furnace, a vacuum is drawn to -0.1 to -0.2 MPa, and then argon gas is introduced at a flow rate of 200-500 ml / min for 5-10 min; while maintaining the argon gas flow, the temperature is increased from room temperature to 800°C at a heating rate of 6-10°C / min, held for 30-60 min, and then increased from 800°C to 900-1300°C at a heating rate of 5-7°C / min; the argon gas flow rate is adjusted to 500-900 ml / min. n. Trichloromethylsilane and hydrogen are simultaneously introduced, with a flow rate of 0.3-0.5 g / min for trichloromethylsilane and 1000-2000 ml / min for hydrogen. While maintaining the introduction of trichloromethylsilane, hydrogen, and argon, the temperature is kept at 900-1300℃ for 2-5 hours, and then the introduction of trichloromethylsilane and hydrogen is stopped. The flow rate of argon is adjusted to 200-500 ml / min, and the temperature is reduced from 900-1300℃ to room temperature at a cooling rate of 10-20℃ / min, and then the introduction of argon is stopped. After chemical vapor deposition, the thickness of the silicon carbide interface layer deposited on the outer surface of a single alumina fiber is 100-500 nm.

[0021] In any of the above embodiments, preferably, in step seven, the alumina fiber cloth preform with the silicon carbide interface layer deposited is immersed in an alumina sol-silica powder slurry. The immersion method is as follows: the alumina sol-silica powder slurry is poured into a container, the alumina fiber cloth preform with the silicon carbide interface layer deposited is placed into the container and immersed below the slurry surface, and an ultrasonic transmitter is placed into the container; the ultrasonic transmitter is activated to treat the alumina fiber cloth for 10-30 minutes to remove air bubbles in the pores of the alumina fiber cloth; after the treatment is completed, the ultrasonic transmitter is removed; the container containing the alumina sol-silica powder slurry and the alumina fiber cloth preform with the silicon carbide interface layer deposited is placed in a vacuum chamber for vacuum immersion, the vacuum is drawn to -0.1--0.5 MPa, and the immersion time is 5-8 hours.

[0022] In any of the above schemes, it is preferred that, in step seven, after the impregnation is completed, the alumina fiber cloth preform is taken out of the container and placed in a drying oven for drying treatment, with a drying temperature of 60-100℃ and a drying time of 10-16h.

[0023] In any of the above schemes, it is preferred that in step eight, the particle-fiber reinforced alumina ceramic matrix composite material green body is subjected to high-temperature sintering. The high-temperature sintering method is as follows: the particle-fiber reinforced alumina ceramic matrix composite material green body is placed in a muffle furnace, heated from room temperature to 800°C at a heating rate of 8-12°C / min, held at that temperature for 1-2 hours, and then heated from 800°C to 900-1000°C at a heating rate of 6-10°C / min, and held at that temperature for 1-4 hours.

[0024] In any of the above schemes, it is preferred that, in step nine, the thickness of the final obtained particle-fiber reinforced alumina ceramic matrix composite material is 10-20 mm.

[0025] In this invention, the muffle furnace, drying oven, chemical vapor deposition furnace, and ultrasonic transmitter used are all existing equipment commonly used in the field, and there are no special requirements for their models. The alumina fiber cloth is woven from alumina fiber bundles, which are composed of bundles of alumina fiber filaments. The dimensions of the graphite rod and alumina fiber cloth are designed according to the actual dimensions of the ion flame detector. To ensure that the final composite material sheath can be smoothly installed onto the outside of the ion flame detector, appropriate gaps need to be reserved in the design based on the actual situation.

[0026] In this invention, the sequence of process steps and the process parameters of each step are crucial in the entire preparation process of the composite material sheath for the ion flame detector. Only by synergistically combining the various process parameters can the expected technical effect of this invention be achieved.

[0027] The method for preparing the oxidation-resistant and corrosion-resistant insulating sheath of the metal tube of the ion flame detector of the present invention has the following beneficial effects:

[0028] (1) Compared with high-temperature alloy materials, the oxidation-resistant and corrosion-resistant insulating sheath prepared by the present invention can overcome the inherent defects of high density and easy oxidation of high-temperature alloy materials; the density of the composite material sheath of the present invention is only 2.3-2.7 g / cm3, which greatly reduces the weight of the sheath and meets the requirements of aircraft weight reduction; as an anti-oxidation material, the composite material sheath of the present invention can be protected from oxidation in high-temperature environments up to 1500℃; the main structure of the composite material sheath of the present invention is alumina fiber reinforced alumina ceramic matrix composite material, which has good insulation properties.

[0029] (2) Compared with ceramic materials, the oxidation-resistant and corrosion-resistant insulating sheath prepared by the present invention can overcome the inherent low toughness of ceramic sheaths; the sheath of the present invention is essentially a particle-fiber reinforced alumina ceramic matrix composite material, which has high toughness and can maintain the stability of shape and properties when subjected to various external loads during the operation of aerospace engines. Attached Figure Description

[0030] Figure 1 This is a process flow diagram of a preferred embodiment of the preparation method of the oxidation-resistant and corrosion-resistant insulating sheath of the metal tube of the ion flame detector according to the present invention;

[0031] Figure 2 for Figure 1 A schematic diagram of the arrangement of alumina fiber cloth and graphite rods before the formation of the tubular alumina fiber cloth preform in the embodiment shown.

[0032] Figure 3 for Figure 1 A schematic diagram of the tubular alumina fiber cloth preform spirally wound with alumina fiber bundle in the embodiment shown.

[0033] Figure 4 for Figure 1 A photograph of the actual metal tube of the ion flame detector prepared according to the embodiment shown; it is resistant to oxidation and corrosion and has an insulating sheath.

[0034] Figure 5 for Figure 1 Scanning electron microscope images of the casing corroded by corrosive gases generated from the combustion of aviation oil in the illustrated embodiment;

[0035] Figure 6 for Figure 1 A scanning electron microscope image of the casing after corrosion by corrosive gases generated from the combustion of aviation oil in the embodiment shown;

[0036] Figure 7 for Figure 1 XRD energy spectrum of the encapsulation without high-temperature oxidation in the illustrated embodiment;

[0037] Figure 8 for Figure 1 The XRD energy spectrum of the coating after high-temperature oxidation in the illustrated embodiment;

[0038] Figure 9 for Figure 1 Photographs showing the insulation performance test of the sheath in the illustrated embodiment.

[0039] The diagram shows the following labels: 1-alumina fiber cloth, 2-graphite rod, 3-alumina fiber bundle, 4-high temperature adhesive, 5-transverse alumina fiber bundle, 6-longitudinal alumina fiber bundle. Detailed Implementation

[0040] To further understand the invention, the following detailed description of the invention will be provided in conjunction with specific embodiments.

[0041] Example 1:

[0042] like Figure 1-3As shown, a preferred embodiment of the method for preparing the oxidation-resistant and corrosion-resistant insulating sheath of the metal tube of the ion flame detector according to the present invention includes the following steps in sequence:

[0043] Step 1: Prepare alumina fiber cloth 1, alumina fiber bundle 3, alumina sol, silica powder and graphite rod 2 according to the design requirements; at the same time, prepare alumina sol-silica powder slurry according to the design requirements.

[0044] Step 2: Pre-treat the alumina fiber cloth 1 according to the design requirements to remove the organic adhesive on the alumina fiber cloth 1.

[0045] Step 3: Lay the pretreated alumina fiber cloth 1 flat on a horizontal surface, place the graphite rod 2 at one end of the alumina fiber cloth 1, and roll the graphite rod 2 from one end of the alumina fiber cloth 1 to the other end to make the alumina fiber cloth 1 wrap around the graphite rod 2, thus obtaining a tubular alumina fiber cloth preform.

[0046] Step 4: Use alumina fiber bundle 3 to spirally wind the tubular alumina fiber cloth preform from one end to the other, and at the same time use high temperature adhesive 4 to fix the two ends of the alumina fiber bundle 3 to the two ends of the graphite rod 2 respectively.

[0047] Step 5: Using the chemical vapor deposition process of the MTS-Ar-H2 reaction system, a silicon carbide interface layer is deposited on the tubular alumina fiber cloth preform, so that the outer surface of each alumina fiber is coated with a silicon carbide interface layer, thereby obtaining an alumina fiber cloth preform with a silicon carbide interface layer deposited on it.

[0048] Step 6: After the silicon carbide interface layer is deposited, the alumina fiber cloth 1 wrapped around the graphite rod 2 is hardened and fixed, and the graphite rod 2 is extracted from the alumina fiber cloth preform with the silicon carbide interface layer deposited.

[0049] Step 7: Immerse the alumina fiber cloth preform with the silicon carbide interface layer in the alumina sol-silica powder slurry. After immersion, remove the alumina fiber cloth preform from the slurry and dry it. After drying, a particle-fiber reinforced alumina ceramic matrix composite preform is obtained.

[0050] Step 8: Place the particle-fiber reinforced alumina ceramic matrix composite green body into a muffle furnace for high-temperature sintering to obtain the particle-fiber reinforced alumina ceramic matrix composite.

[0051] Step 9: Weigh the particle-fiber reinforced alumina ceramic matrix composite material after high-temperature sintering and record the weighing data; repeat steps 7 and 8 until the mass of the particle-fiber reinforced alumina ceramic matrix composite material increases by less than 5 wt% compared to the previous mass, and use it as the sheath for the metal tube of the ion flame detector.

[0052] In step one, the graphite rod 2 has a diameter of 12 mm and a length of 10 cm; the alumina fiber cloth 1 is woven from transverse alumina fiber bundles 5 and longitudinal alumina fiber bundles 6, with the width of the transverse alumina fiber bundle 5 being 1.1 mm and the width of the longitudinal alumina fiber bundle 6 being 1.1 mm, and the thickness of the alumina fiber cloth 1 being 0.3 mm; the alumina fiber bundle 3 is composed of 1000 alumina fiber filaments bundled together; the alumina sol has a pH value of 4.0 and a density of 1.25 g / cm³. 3 The viscosity is 15 C·P, the alumina content in the alumina sol is 40 wt%, the particle size of the alumina is 5 nm, and the particle size of the silica powder is 250 nm.

[0053] The method for preparing the alumina sol-silica powder slurry is as follows: silica powder is added to alumina sol and stirred for 2 hours to ensure that the silica powder is uniformly dispersed in the alumina sol; wherein the silica powder accounts for 20 wt% of the slurry by mass and the alumina sol accounts for 80 wt% of the slurry by mass.

[0054] In step two, the pretreatment process for the alumina fiber cloth is as follows: the alumina fiber cloth is placed in a muffle furnace and heated from room temperature to 550°C at a heating rate of 9°C / min, held at that temperature for 2 hours, and then allowed to cool naturally to room temperature.

[0055] In step three, the alumina fiber cloth is wound 25 layers around the graphite rod.

[0056] In step five, the chemical vapor deposition process for the tubular alumina fiber cloth preform is as follows: the tubular alumina fiber cloth preform is placed in a chemical vapor deposition furnace, a vacuum is drawn to -0.15 MPa, and then argon gas is introduced at a flow rate of 350 ml / min for 8 min. While maintaining the argon gas flow, the temperature is increased from room temperature to 800°C at a heating rate of 8°C / min, held for 45 min, and then increased from 800°C to 1100°C at a heating rate of 6°C / min. The argon gas flow rate is then adjusted to 700 ml / min, and argon gas is introduced simultaneously. Trichloromethylsilane and hydrogen were used, with a flow rate of 0.4 g / min for trichloromethylsilane and 1500 ml / min for hydrogen. The mixture was kept at 1100 °C for 3.5 h while maintaining the flow of trichloromethylsilane, hydrogen, and argon. Then, the flow of trichloromethylsilane and hydrogen was stopped. The flow rate of argon was adjusted to 350 ml / min, and the temperature was lowered from 1100 °C to room temperature at a rate of 15 °C / min. After chemical vapor deposition, the thickness of the silicon carbide interface layer deposited on the outer surface of a single alumina fiber was 300 nm.

[0057] In step seven, the alumina fiber cloth preform with a silicon carbide interface layer deposited is immersed in an alumina sol-silica powder slurry. The immersion method is as follows: the alumina sol-silica powder slurry is poured into a container, the alumina fiber cloth preform with the silicon carbide interface layer deposited is placed into the container and immersed below the slurry surface, and an ultrasonic transmitter is placed in the container; the ultrasonic transmitter is activated to treat the alumina fiber cloth for 20 minutes to remove air bubbles in the pores of the alumina fiber cloth. After the treatment is completed, the ultrasonic transmitter is removed; the container containing the alumina sol-silica powder slurry and the alumina fiber cloth preform with the silicon carbide interface layer deposited is placed in a vacuum chamber for vacuum immersion, the vacuum is drawn to -0.3 MPa, and the immersion time is 6.5 hours.

[0058] After impregnation, remove the alumina fiber cloth preform from the container and place it in a drying oven for drying at 80°C for 13 hours.

[0059] In step eight, the particle-fiber reinforced alumina ceramic matrix composite green body is subjected to high-temperature sintering. The high-temperature sintering method is as follows: the particle-fiber reinforced alumina ceramic matrix composite green body is placed in a muffle furnace and heated from room temperature to 800°C at a heating rate of 10°C / min, held at that temperature for 1.5h, and then heated from 800°C to 1050°C at a heating rate of 8°C / min, held at that temperature for 2.5h.

[0060] In step nine, the final particle-fiber reinforced alumina ceramic matrix composite material has a thickness of 15 mm.

[0061] A photograph of the actual metal tube of the ion flame detector prepared in this embodiment, which is resistant to oxidation and corrosion and has an insulating sheath, is shown below. Figure 4 As shown in the figure, the casing has been cut in half. Block samples, 5mm × 5mm in size, were cut from the casing of the particle-fiber reinforced alumina ceramic matrix composite for corrosion resistance testing. The blocks were immersed in aviation engine oil for 500 hours. After immersion, the blocks were removed, ultrasonically cleaned, and then dried in a muffle furnace at 100℃ for 12 hours. A scanning electron microscope image of the block sample not immersed in aviation engine oil is shown below. Figure 5 As shown, the scanning electron microscope image of the block sample after being soaked in aviation oil is as follows: Figure 6 As shown, comparison Figure 5 and Figure 6 It can be observed that the block sample did not show significant morphological changes after being soaked in aviation engine oil for 500 hours, indicating that the block sample has good corrosion resistance.

[0062] Block samples, measuring 5 mm × 5 mm, were cut from the casing of a particle-fiber reinforced alumina ceramic matrix composite for high-temperature oxidation resistance testing. The samples were placed in a muffle furnace and heated to 1000℃ for 10 hours. After heating, the samples were allowed to cool naturally to room temperature, and then the energy dispersive X-ray diffraction (EDS) spectra were measured. The EDS spectra of the unoxidized block samples are shown below. Figure 7 As shown, the XRD energy spectrum of the block sample after high-temperature oxidation is as follows: Figure 8 As shown, comparison Figure 7 and Figure 8 It can be observed that the phase of the block sample did not change after being heated at high temperature, which indicates that the block sample has good resistance to high-temperature oxidation.

[0063] The resistance of the particle-fiber reinforced alumina ceramic matrix composite sheath was tested using a multimeter set to 20 megohms. The test result showed a resistance of 0, indicating that the composite sheath has good insulation properties. The insulation performance of the sheath was tested as follows: Figure 9 As shown.

[0064] In this embodiment, the muffle furnace, drying oven, chemical vapor deposition furnace, and ultrasonic transmitter used are all existing equipment commonly used in the field, and there are no special requirements for their models. The alumina fiber cloth is woven from alumina fiber bundles, which are composed of bundles of alumina fiber filaments. Throughout the entire preparation process of the composite material sheath for the ion flame detector, the sequence of process steps and the process parameters for each step are crucial. Only by synergistically applying these process parameters can the intended technical effect of this invention be achieved.

[0065] The method for preparing the oxidation-resistant and corrosion-resistant insulating sheath of the metal tube of the ion flame detector in this embodiment has the following beneficial effects:

[0066] (1) The prepared composite material sheath can overcome the inherent defects of high density and easy oxidation of high temperature alloy sheath. The density of the composite material sheath is low, which greatly reduces the weight of the sheath. The composite material sheath can not be oxidized in a high temperature environment of up to 1500℃. At the same time, the main structure of the composite material sheath is alumina fiber reinforced alumina ceramic matrix composite material, which has good insulation properties. (2) The prepared composite material sheath can overcome the inherent defects of low toughness of ceramic sheath. The sheath is essentially a particle-fiber reinforced alumina ceramic matrix composite material, which has high toughness. When subjected to various external loads during the operation of aerospace engines, it can maintain the stability of shape and properties.

[0067] Example 2:

[0068] Another preferred embodiment of the method for preparing the oxidation-resistant and corrosion-resistant insulating sheath of the metal tube of the ion flame detector according to the present invention has the same process steps, technical principles, equipment used, and beneficial effects as that of Embodiment 1, except that:

[0069] In step one, the graphite rod has a diameter of 12 mm and a length of 10 cm; the alumina fiber cloth is woven from transverse and longitudinal alumina fiber bundles, with each transverse alumina fiber bundle having a width of 0.8 mm and each longitudinal alumina fiber bundle having a width of 0.8 mm; the alumina fiber cloth has a thickness of 0.2 mm; each alumina fiber bundle is composed of 500 alumina fiber filaments; the alumina sol has a pH of 3.0 and a density of 1.2 g / cm³. 3 The viscosity is 15 C·P, the alumina content in the alumina sol is 35 wt%, the particle size of the alumina is 1 nm, and the particle size of the silica powder is 10 nm.

[0070] The method for preparing the alumina sol-silica powder slurry is as follows: silica powder is added to alumina sol and stirred for 1 hour to ensure that the silica powder is uniformly dispersed in the alumina sol; wherein the silica powder accounts for 10 wt% of the slurry by mass and the alumina sol accounts for 90 wt% of the slurry by mass.

[0071] In step two, the pretreatment process for the alumina fiber cloth is as follows: the alumina fiber cloth is placed in a muffle furnace and heated from room temperature to 400°C at a heating rate of 6°C / min, held at that temperature for 3 hours, and then allowed to cool naturally back to room temperature.

[0072] In step three, the alumina fiber cloth is wound five layers around the graphite rod.

[0073] In step five, the chemical vapor deposition process for the tubular alumina fiber cloth preform is as follows: the tubular alumina fiber cloth preform is placed in a chemical vapor deposition furnace, a vacuum is drawn to -0.1 MPa, and then argon gas is introduced at a flow rate of 200 ml / min for 10 min; while maintaining the argon gas flow, the temperature is increased from room temperature to 800°C at a heating rate of 6°C / min, held for 30 min, and then increased from 800°C to 900°C at a heating rate of 5°C / min; the argon gas flow rate is adjusted to 500 ml / min, and simultaneously... Trichloromethylsilane and hydrogen were introduced at a flow rate of 0.3 g / min and a flow rate of 1000 ml / min. The mixture was kept at 900°C for 5 hours while maintaining the flow of trichloromethylsilane, hydrogen, and argon. Then, the flow of trichloromethylsilane and hydrogen was stopped. The flow rate of argon was adjusted to 200 ml / min, and the temperature was lowered from 900°C to room temperature at a rate of 10°C / min. After chemical vapor deposition, the thickness of the silicon carbide interface layer deposited on the outer surface of a single alumina fiber was 100 nm.

[0074] In step seven, the alumina fiber cloth preform with a silicon carbide interface layer deposited is immersed in an alumina sol-silica powder slurry. The immersion method is as follows: the alumina sol-silica powder slurry is poured into a container, the alumina fiber cloth preform with the silicon carbide interface layer deposited is placed into the container and immersed below the slurry surface, and an ultrasonic transmitter is placed in the container; the ultrasonic transmitter is activated to treat the alumina fiber cloth for 10 minutes to remove air bubbles in the pores of the alumina fiber cloth. After the treatment is completed, the ultrasonic transmitter is removed; the container containing the alumina sol-silica powder slurry and the alumina fiber cloth preform with the silicon carbide interface layer deposited is placed in a vacuum chamber for vacuum immersion, the vacuum is drawn to -0.1 MPa, and the immersion time is 5 hours.

[0075] After impregnation, the alumina fiber cloth preform is removed from the container and placed in a drying oven for drying at 60°C for 16 hours.

[0076] In step eight, the particle-fiber reinforced alumina ceramic matrix composite green body is subjected to high-temperature sintering. The high-temperature sintering method is as follows: the particle-fiber reinforced alumina ceramic matrix composite green body is placed in a muffle furnace and heated from room temperature to 800°C at a heating rate of 8°C / min, held at that temperature for 2 hours, and then heated from 800°C to 900°C at a heating rate of 6°C / min, held at that temperature for 4 hours.

[0077] In step nine, the final particle-fiber reinforced alumina ceramic matrix composite material has a thickness of 10 mm.

[0078] Example 3:

[0079] Another preferred embodiment of the method for preparing the oxidation-resistant and corrosion-resistant insulating sheath of the metal tube of the ion flame detector according to the present invention has the same process steps, technical principles, equipment used, and beneficial effects as that of Embodiment 1, except that:

[0080] In step one, the graphite rod has a diameter of 12 mm and a length of 10 cm; the alumina fiber cloth is woven from transverse and longitudinal alumina fiber bundles, with each transverse alumina fiber bundle having a width of 1.4 mm and each longitudinal alumina fiber bundle having a width of 1.4 mm; the alumina fiber cloth has a thickness of 0.4 mm; each alumina fiber bundle is composed of 2000 alumina fiber filaments; the alumina sol has a pH of 5.0 and a density of 1.3 g / cm³. 3 The viscosity is 15 C·P, the alumina content in the alumina sol is 45 wt%, the particle size of the alumina is 10 nm, and the particle size of the silica powder is 500 nm.

[0081] The method for preparing the alumina sol-silica powder slurry is as follows: silica powder is added to alumina sol and stirred for 3 hours to ensure that the silica powder is uniformly dispersed in the alumina sol; wherein the silica powder accounts for 30 wt% of the slurry by mass and the alumina sol accounts for 70 wt% of the slurry by mass.

[0082] In step two, the pretreatment process for the alumina fiber cloth is as follows: the alumina fiber cloth is placed in a muffle furnace and heated from room temperature to 700°C at a heating rate of 12°C / min, held at that temperature for 1 hour, and then allowed to cool naturally back to room temperature.

[0083] In step three, the alumina fiber cloth is wound 50 layers around the graphite rod.

[0084] In step five, the chemical vapor deposition process for the tubular alumina fiber cloth preform is as follows: the tubular alumina fiber cloth preform is placed in a chemical vapor deposition furnace, a vacuum is drawn to -0.2 MPa, and then argon gas is introduced at a flow rate of 500 ml / min for 5 min; while maintaining the argon gas flow, the temperature is increased from room temperature to 800°C at a heating rate of 10°C / min, held at that temperature for 60 min, and then increased from 800°C to 1300°C at a heating rate of 7°C / min; the argon gas flow rate is adjusted to 900 ml / min, and simultaneously... Trichloromethylsilane and hydrogen were introduced at a flow rate of 0.5 g / min and a flow rate of 2000 ml / min. The mixture was kept at 1300 °C for 2 hours while maintaining the flow of trichloromethylsilane, hydrogen, and argon. Then, the flow of trichloromethylsilane and hydrogen was stopped. The flow rate of argon was adjusted to 500 ml / min, and the temperature was lowered from 1300 °C to room temperature at a rate of 20 °C / min. After chemical vapor deposition, the thickness of the silicon carbide interface layer deposited on the outer surface of a single alumina fiber was 500 nm.

[0085] In step seven, the alumina fiber cloth preform with the silicon carbide interface layer deposited is immersed in an alumina sol-silica powder slurry. The immersion method is as follows: the alumina sol-silica powder slurry is poured into a container, the alumina fiber cloth preform with the silicon carbide interface layer deposited is placed into the container and immersed below the slurry surface, and an ultrasonic transmitter is placed in the container; the ultrasonic transmitter is activated to treat the alumina fiber cloth for 30 minutes to remove air bubbles in the pores of the alumina fiber cloth. After the treatment is completed, the ultrasonic transmitter is removed; the container containing the alumina sol-silica powder slurry and the alumina fiber cloth preform with the silicon carbide interface layer deposited is placed in a vacuum chamber for vacuum immersion, the vacuum is drawn to -0.5 MPa, and the immersion time is 8 hours.

[0086] After impregnation, remove the alumina fiber cloth preform from the container and place it in a drying oven for drying at 100℃ for 10 hours.

[0087] In step eight, the particle-fiber reinforced alumina ceramic matrix composite green body is subjected to high-temperature sintering. The high-temperature sintering method is as follows: the particle-fiber reinforced alumina ceramic matrix composite green body is placed in a muffle furnace and heated from room temperature to 800°C at a heating rate of 12°C / min, held at that temperature for 1 hour, and then heated from 800°C to 1000°C at a heating rate of 10°C / min, held at that temperature for 1 hour.

[0088] In step nine, the final particle-fiber reinforced alumina ceramic matrix composite material has a thickness of 20 mm.

[0089] Special Note: The technical solution of this invention involves numerous parameters, and the synergistic effects between these parameters must be comprehensively considered to achieve the beneficial effects and significant progress of this invention. Furthermore, the value ranges of each parameter in the technical solution were obtained through extensive experimentation. For each parameter and the combinations thereof, the inventors have recorded a large amount of experimental data; however, due to space limitations, the specific experimental data is not disclosed here.

[0090] Those skilled in the art will readily understand that the method for preparing the oxidation-resistant and corrosion-resistant insulating sheath of the ion flame detector metal tube of the present invention includes any combination of the inventive content and specific embodiments described in the above specification and the various parts shown in the accompanying drawings. Due to space limitations and for the sake of brevity, not all of these combinations have been described in detail. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an oxidation-resistant and corrosion-resistant insulating sheath for an ion flame detector metal tube, characterized in that, The preparation method includes the following steps in sequence: Step 1: Prepare alumina fiber cloth, alumina fiber bundles, alumina sol, silica powder, and graphite rods according to the design requirements; at the same time, prepare alumina sol-silica powder slurry according to the design requirements. Step 2: Pre-treat the alumina fiber cloth according to the design requirements to remove the organic adhesive on the alumina fiber cloth; Step 3: Lay the pretreated alumina fiber cloth flat on a horizontal surface, place a graphite rod at one end of the alumina fiber cloth, and roll the graphite rod from one end of the alumina fiber cloth to the other end to make the alumina fiber cloth wrap around the graphite rod, thus obtaining a tubular alumina fiber cloth preform. Step 4: Use alumina fiber bundles to spirally wind around the outside of the tubular alumina fiber cloth preform from one end to the other, and at the same time use high-temperature adhesive to fix the two ends of the alumina fiber bundles to the two ends of the graphite rod respectively. Step 5: Using the chemical vapor deposition process of the MTS-Ar-H2 reaction system, a silicon carbide interface layer is deposited on the tubular alumina fiber cloth preform, so that the outer surface of each alumina fiber is coated with a silicon carbide interface layer, thereby obtaining an alumina fiber cloth preform with a silicon carbide interface layer deposited on it. Step 6: After the silicon carbide interface layer is deposited, the alumina fiber cloth wrapped around the graphite rod is hardened and fixed, and the graphite rod is extracted from the alumina fiber cloth preform with the silicon carbide interface layer deposited. Step 7: Immerse the alumina fiber cloth preform with the silicon carbide interface layer in the alumina sol-silica powder slurry. After immersion, remove the alumina fiber cloth preform from the slurry and dry it. After drying, a particle-fiber reinforced alumina ceramic matrix composite preform is obtained. Step 8: Place the particle-fiber reinforced alumina ceramic matrix composite green body into a muffle furnace for high-temperature sintering to obtain the particle-fiber reinforced alumina ceramic matrix composite. Step 9: Weigh the particle-fiber reinforced alumina ceramic matrix composite material after high-temperature sintering and record the weighing data; repeat steps 7 and 8 until the mass of the particle-fiber reinforced alumina ceramic matrix composite material increases by less than 5 wt% compared to the previous mass, and use it as the sheath for the metal tube of the ion flame detector. In step one, the alumina fiber cloth is woven from transverse and longitudinal alumina fiber bundles. The width of the transverse alumina fiber bundle is 0.8-1.4 mm, the width of the longitudinal alumina fiber bundle is 0.8-1.4 mm, and the thickness of the alumina fiber cloth is 0.2-0.4 mm. Each alumina fiber bundle consists of 500-2000 alumina fiber filaments. The alumina sol has a pH value of 3.0-5.0 and a density of 1.2-1.3 g / cm³. 3 The viscosity does not exceed 15 C·P, the alumina content in the alumina sol is 35-45 wt%, the particle size of the alumina is 1-10 nm; the particle size of the silica powder is 10-500 nm. In step five, the chemical vapor deposition process for the tubular alumina fiber cloth preform is as follows: the tubular alumina fiber cloth preform is placed in a chemical vapor deposition furnace, and a vacuum is drawn to -0.1 to -0.2 MPa. Then, argon gas is introduced at a flow rate of 200-500 ml / min for 5-10 min. While maintaining the argon gas flow, the temperature is increased from room temperature to 800°C at a rate of 6-10°C / min, held for 30-60 min, and then increased from 800°C to 900-1300°C at a rate of 5-7°C / min. The argon gas flow rate is adjusted to 500-900 ml / min, and three... The process involves using chloromethylsilane and hydrogen, with the flow rate of chloromethylsilane being 0.3-0.5 g / min and the flow rate of hydrogen being 1000-2000 ml / min. While maintaining the flow of chloromethylsilane, hydrogen, and argon, the temperature is kept at 900-1300℃ for 2-5 hours, then the flow of chloromethylsilane and hydrogen is stopped. The flow rate of argon is adjusted to 200-500 ml / min, and the temperature is simultaneously reduced from 900-1300℃ to room temperature at a cooling rate of 10-20℃ / min, then the flow of argon is stopped. After chemical vapor deposition, the thickness of the silicon carbide interface layer deposited on the outer surface of a single alumina fiber is 100-500 nm.

2. The method for preparing the oxidation-resistant and corrosion-resistant insulating sheath of the metal tube for the ion flame detector according to claim 1, characterized in that, In step one, the method for preparing the alumina sol-silica powder slurry is as follows: silica powder is added to alumina sol and stirred for 1-3 hours to ensure that the silica powder is uniformly dispersed in the alumina sol; wherein the silica powder accounts for 10-30 wt% of the slurry by mass, and the alumina sol accounts for 70-90 wt% of the slurry by mass.

3. The method for preparing the oxidation-resistant and corrosion-resistant insulating sheath of the metal tube of the ion flame detector according to claim 2, characterized in that, In step two, the pretreatment process for the alumina fiber cloth is as follows: the alumina fiber cloth is placed in a muffle furnace and heated from room temperature to 400-700℃ at a heating rate of 6-12℃ / min, held at that temperature for 1-3 hours, and then allowed to cool naturally to room temperature.

4. The method of claim 3, wherein the metal tube of the ion flame detector is made of stainless steel. 5 In step three, the alumina fiber cloth is wound 5-50 layers onto the graphite rod.

5. The method for preparing the oxidation-resistant and corrosion-resistant insulating sheath of the metal tube of the ion flame detector according to claim 4, characterized in that, In step seven, the alumina fiber cloth preform with the silicon carbide interface layer deposited is immersed in an alumina sol-silica powder slurry. The immersion method is as follows: the alumina sol-silica powder slurry is poured into a container, the alumina fiber cloth preform with the silicon carbide interface layer deposited is placed into the container and immersed below the slurry surface, and an ultrasonic transmitter is placed into the container; the ultrasonic transmitter is activated to treat the alumina fiber cloth for 10-30 minutes to remove air bubbles in the pores of the alumina fiber cloth. After the treatment is completed, the ultrasonic transmitter is removed; the container containing the alumina sol-silica powder slurry and the alumina fiber cloth preform with the silicon carbide interface layer deposited is placed in a vacuum chamber for vacuum immersion, the vacuum is drawn to -0.1 to -0.5 MPa, and the immersion time is 5-8 hours.

6. The method for preparing the oxidation-resistant and corrosion-resistant insulating sheath of the metal tube of the ion flame detector according to claim 5, characterized in that, In step seven, after the impregnation is completed, the alumina fiber cloth preform is taken out of the container and placed in a drying oven for drying treatment. The drying temperature is 60-100℃ and the drying time is 10-16 hours.

7. The method for preparing the oxidation-resistant and corrosion-resistant insulating sheath of the metal tube of the ion flame detector according to claim 6, characterized in that, In step eight, the particle-fiber reinforced alumina ceramic matrix composite green body is subjected to high-temperature sintering. The high-temperature sintering method is as follows: the particle-fiber reinforced alumina ceramic matrix composite green body is placed in a muffle furnace and heated from room temperature to 800℃ at a heating rate of 8-12℃ / min, held at that temperature for 1-2 hours, and then heated from 800℃ to 900-1000℃ at a heating rate of 6-10℃ / min, held at that temperature for 1-4 hours.

8. The method for preparing the oxidation-resistant and corrosion-resistant insulating sheath of the metal tube of the ion flame detector according to claim 7, characterized in that, In step nine, the final particle-fiber reinforced alumina ceramic matrix composite material has a thickness of 10-20 mm.

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