CN114842572B - Flight parameter recorder heat protection sleeve based on enthalpy change nanometer heat insulation material - Google Patents

Abstract

The invention relates to a flight parameter recorder thermal protection sleeve based on an enthalpy-variable nano heat insulation material, belonging to the field of flight parameter recorders; the enthalpy-variable nano heat insulation lining is arranged inside the outer structure shell, and the outer side of the shell is sealed; the protected data chip is arranged at the center of the inner sealing shell, and sealing filler is filled between the protected data chip and the inner sealing shell; the sealing material is filled in the ventilation channel and is used for airtight sealing at normal temperature, a gaseous product after enthalpy change of the enthalpy-changing nano heat insulation lining forms an air film on the surface of the outer structure shell of the flight parameter recorder in a burning state, the convective heat transfer of flame to the flight parameter recorder is slowed down, the sealing filler prevents the gaseous product from penetrating into the inner sealing shell to contact with the protected data chip, and the sealing material in the ventilation channel is ablated and volatilized, so that the ventilation channel is communicated with an external space and the enthalpy-changing nano heat insulation lining.

Description

A thermal protective sleeve for flight parameter recorders based on enthalpy-changeable nano-insulation materials

Technical field

The invention relates to the field of flight parameter recorders, in particular to a thermal protective sleeve for flight parameter recorders based on enthalpy-changeable nano-insulation materials.

Background technique

The flight parameter recorder is used to record the working status of the aircraft and the pilot's operation, providing objective and effective basis for flight accident investigation. In order for the data in the recorder to be completely preserved after a crash, the flight parameter recorder needs to have the ability to survive high-temperature fire (1100°C) and medium-temperature baking (260°C). The European Aeronautical Equipment Organization's ED-112 "Minimum Operating Performance Requirements for Crash Resistant Airborne Recording Systems" and the FAA's TSO-C124b "Technical Standard for Flight Data Recording Systems" both stipulate that flight parameter recorders must withstand 900 to 1100 ℃ flame ablation requirement for at least 1 hour. On the basis of this thermal insulation requirement, new drones and military fighter aircraft avionics systems also have high requirements on the weight and volume of flight parameter recorders, which require flight parameter recorders to reduce weight and volume as much as possible.

The existing flight parameter thermal protection method uses heat reflection, heat insulation, and heat storage to improve the thermal protection capability of the flight parameter recorder. The assembly structure is complex and it is difficult to further reduce the overall weight and volume. Therefore, new thermal protection materials and thermal protection structures with multiple thermal insulation functions are needed to further improve the overall thermal protection capability and structural compactness of the flight parameter recorder, so as to achieve weight and volume reduction requirements.

Contents of the invention

The technical problem solved by the present invention is to overcome the shortcomings of the existing technology, provide a thermal protective sleeve for a flight parameter recorder based on enthalpy-changeable nano-insulation materials, enhance the structural compactness of the flight parameter recorder, reduce the difficulty of assembly, and at the same time It is possible to reduce the weight and volume of the flight parameter recorder while ensuring the thermal insulation performance.

The technical solution of the present invention is: a thermal protective sleeve for flight parameter recorders based on enthalpy-changeable nano-insulation materials. The protective sleeve includes an enthalpy-changeable nano-insulation lining, an outer structural shell, a heat-reflective coating, Inner sealing shell, inner sealing packing and N ventilation channels, N is greater than or equal to 1;

The enthalpy-changeable nano-insulation lining is installed inside the outer structural shell and outside the inner sealing shell, and is in direct contact with the two; the inner sealing shell, the protected data chip and the sealing filler are all located in the enthalpy-changeable nano-insulation lining. Inside, the protected data chip is installed in the center of the inner sealing case, and sealing filler is filled between the protected data chip and the inner sealing case; each breathable channel is set in the outer structure shell structure, and the inner opening of the breathable channel is capable of enthalpy change. The nano thermal insulation lining is in contact with the outside world, and the breathable channel is filled with sealing material. At normal temperature, the sealing material is used for airtight sealing; in the fire state, the enthalpy-changing nano thermal insulation lining has both thermal insulation and The enthalpy change absorbs heat. The gaseous products after the enthalpy change form a gas film on the surface of the outer structural shell of the flight parameter recorder, slowing down the convective heat transfer of the flame to the flight parameter recorder. The sealing filler is used to prevent gaseous products from penetrating into the inner seal. When the shell comes into contact with the protected data chip, the sealing material in the breathable channel is ablated and volatilized, allowing the breathable channel to connect the external space with the enthalpy-changing nano-insulation lining.

Preferably, the ventilation channel has an internal thread structure.

Preferably, the breathable channel with built-in sealing material can pass the 0.4MPa/1h airtight sealing test at normal temperature.

Preferably, under the high temperature fire condition of 1100°C, the sealing material in the ventilation channel can be ablated and volatilized within 10 minutes, so that the opening area ratio of the ventilation channel is greater than 80%.

Preferably, the density of the enthalpy-changeable nano thermal insulation lining is 0.45-0.8g/cm ³ , the thermal conductivity at room temperature is less than 0.03W/(m·K), the compressive strength is greater than 0.5MPa, and the latent enthalpy heat absorption >600kJ/kg.

Preferably, the enthalpy-changeable nano-insulation lining material is an enthalpy-changeable nano-insulation material, which is composed of high-temperature-resistant nano-powder, enthalpy-change material nano-powder, ceramic reinforcing fiber, and sunscreen agent powder, wherein the high-temperature-resistant nano insulating material The powder is one or more of nano-silica, nano-alumina, and nano-mullite; the enthalpy-changeable material nano-powder is one or more of aluminum hydroxide, boric acid, hydrated magnesium chloride, calcium carbonate, and lithium carbonate. Ceramic reinforced fiber is one of quartz chopped fiber, glass chopped fiber, zirconia fiber, silicon nitride chopped fiber, mullite fiber, alumina fiber, high silica fiber, basalt fiber, silicon carbide fiber or Several, the sunscreen powder is one or more of silicon carbide powder, titanium oxide powder, zirconium oxide powder, zirconium silicate powder, chromium oxide powder, and iron oxide powder.

Preferably, the components and density of the enthalpy-changeable nano thermal insulation lining are determined according to the following method:

S1. Set the initial overall density of the enthalpy-changeable nano-insulation material;

S2. Select the enthalpy-changeable material nanopowder according to the temperature-resistant allowable temperature of the protected data chip, and select the enthalpy-changing material nanopowder with the highest latent enthalpy heating value within the range where the latent enthalpy change temperature is higher than the temperature-resistant allowable temperature of the protected data chip. Variable material nanopowders;

S3. According to the preset ratio, prepare a sample of the enthalpy-changeable nano-insulation material so that the density of the enthalpy-changeable nano-insulation material is the initial overall density determined in step S1;

S4. Conduct thermal conductivity testing and differential thermal analysis on the enthalpy-changeable nano-insulation material samples to obtain the actual thermal conductivity, latent enthalpy change temperature point and latent enthalpy heat value of the enthalpy-changeable nano-insulation material;

S5. Based on the actual thermal conductivity, latent enthalpy change temperature point and latent enthalpy heat value of the enthalpy-changeable nano-insulation material sample, use the fire test thermal field simulation process to conduct the fire test thermal field simulation to obtain the protected data chip The thickness of the enthalpy-changeable nano thermal insulation lining whose temperature does not exceed the allowable temperature resistance temperature;

S6. Determine whether the thickness of the enthalpy-changeable nano thermal insulation lining meets the preset thickness requirements. If it meets the preset thickness requirements, proceed to step S7. If not, increase the proportion of the enthalpy-changeable material and re-execute steps S3 to S6;

S7. Carry out actual fire test assessment. If the final temperature Tc,ex of the protected data chip after the fire test is lower than the allowable temperature resistance of the protected data chip, proceed to step S8; if the chip exceeds the allowable temperature resistance of the chip, compare the fire Whether the difference between the final temperature T _c,ex of the protected data chip after the test and the final temperature T _c calculated by the simulation in step S5 is lower than the allowable deviation ΔT, if |T _c,ex -T _c |＞ΔT, Correct the thermal field environment temperature in the simulation model of step, and re-execute steps S5~S7; if |T _c,ex -T _c |<ΔT, increase the overall density ρ of the enthalpy-changeable nano-insulation material, and re-execute S3~ S7, until the final temperature of the protected data chip is lower than the allowable temperature of the chip after the fire test.

Preferably, the relationship between the initial overall density and the upper limit of the overall density is: ρ ₀ = (0.7 ~ 0.9) ρ _max , the upper limit of the overall density of the enthalpy-changeable nano-insulation material ρ _max , according to the overall density of the flight parameter recorder thermal protective sleeve Weight requirements are extrapolated and do not exceed the overall density of the flight parameter recorder thermal jacket.

Preferably, the preset proportion of each component in the enthalpy changeable nano thermal insulation material sample in step S3 is: the initial addition proportion of the enthalpy changeable material nano powder is 20 to 40 wt%, and the remaining components are high temperature nano powder, accounting for The ratio is 40 to 65wt%, the ceramic reinforcing fiber is 5 to 10wt%, and the sunscreen powder is 5 to 10wt%.

Preferably, the steps for preparing the enthalpy-changeable nano thermal insulation lining are as follows:

S3.1. Mix and disperse the enthalpy changeable material nanopowder and high temperature resistant nanopowder according to the mass ratio of 2:1;

S3.2. Use a ball mill to grind the dispersed mixed powder to grind the enthalpy changeable material nanopowder to a particle size of less than 800 nm;

S3.3. Mix the ground mixed powder with the remaining high-temperature resistant nanopowder, opacifier powder and ceramic reinforcing fiber;

S3.4. According to the initial overall density of the enthalpy-changeable nano-thermal insulation material, the mixed raw materials are dry-molded to prepare the enthalpy-changeable nano-thermal insulation material, which is used as the blank of the enthalpy-changeable nano-thermal insulation lining;

S3.5. According to the thickness of the enthalpy-changeable nano-insulation lining, use a milling machine to process the blank of the enthalpy-changeable nano-insulation lining, and mill out the shape for assembling the inner sealing shell.

Compared with the prior art, the beneficial effects of the present invention are:

(1) The present invention uses heat-insulation/heat-absorption integrated enthalpy-changeable nano-insulation materials to make the thermal protection structure of the flight parameter recorder, which can achieve heat insulation at the same time (thermal conductivity <0.03W/(m·K)) and enthalpy change heat absorption (latent enthalpy heat absorption >600kJ/kg), thereby effectively reducing the heat flowing into the flight parameter recorder;

(2) The present invention uses enthalpy-changeable nano thermal insulation materials to integrate and replace single phase change thermal insulation materials and single thermal insulation materials. It can eliminate the separation device between phase change materials and thermal insulation materials and reduce the weight of the flight parameter recorder;

(3) The present invention uses enthalpy-changeable nano-insulation materials to perform the physical endothermic process of solid-gas phase change or the chemical endothermic process of thermal liberation of gas. The gaseous phase change products or vaporization products of chemical reactions after phase change can be discharged through the high-temperature ventilation holes, forming a gas film on the surface of the flight parameter recorder to reduce the heat transfer of the high-temperature flame to the flight parameter recorder;

(4) The enthalpy-changeable nano thermal insulation material used in the present invention combines the heat-absorbing enthalpy-changeable material into the thermal insulation material, eliminating the need to encapsulate phase change materials in the flight parameter recorder, reducing process complexity and cost. ;

(5) The enthalpy-changeable nano-insulation materials and heat-reflective coatings used in the present invention are inorganic materials and will not age or deteriorate, ensuring the long-term effectiveness of the thermal protection function of the flight parameter recorder.

Description of the drawings

Figure 1 is a schematic structural diagram of the thermal protection shell of a flight parameter recorder based on enthalpy-changeable nano-insulation materials according to an embodiment of the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments:

Figure 1 is a schematic structural diagram of a thermal protective sleeve for a flight parameter recorder based on enthalpy-changeable nano-insulation materials. As can be seen from Figure 1, the thermal protection sleeve for a flight parameter recorder based on enthalpy-changeable nano-insulation materials provided by the present invention The set includes an enthalpy-changeable nano thermal insulation lining 3, an outer structural shell 2, a heat reflective coating 1, an inner sealing shell 7, an inner sealing filler 6 and N ventilation channels 4, where N is greater than or equal to 1. Among them, the enthalpy-changeable nano thermal insulation lining 3 is installed inside the outer structural shell 2 , and is in direct contact with the outer structural shell 2 and the inner sealing shell 7 on the outside of the inner sealing shell 7 . The protected data chip 5 is installed in the center of the inner sealing case 7 , and sealing filler 6 is filled between the protected data chip 5 and the inner sealing case 7 ; each ventilation channel 4 is arranged in the structure of the outer structural shell 2 , and the ventilation channel 4 The inner opening is in contact with the enthalpy-changeable nano-insulation lining 3, the outer opening is in contact with the outside world, and the breathable channel 4 is filled with sealing material. At normal temperature, the sealing material is used for airtight sealing.

The enthalpy-changeable nano thermal insulation lining 3 has both heat insulation and enthalpy change endothermic effects. The gaseous product after the enthalpy change forms a gas film on the surface of the outer structural shell 2 of the flight parameter recorder, slowing down the damage of the flame to the flight parameter recorder. Convective heat transfer, the sealing filler 6 is used to prevent the gaseous product after enthalpy change from penetrating into the inner sealing case 7 and contacting the protected data chip 5; after the sealing material in the breathable channel 4 is ablated and volatilized, the breathable channel 4 is connected External space and enthalpy changeable nano thermal insulation lining 3.

The thermal protective cover of the flight parameter recorder of the present invention comprehensively uses nano-heat insulation technology, phase change/thermal desorption heat absorption technology, hot surface heat reflection technology and heat insulation means of surface air film blocking heat convection. Among them, enthalpy-changeable nano-thermal insulation materials have the functions of nano-thermal insulation, phase change/thermal desorption heat, and air film blocking thermal convection. The surface heat-reflective coating can realize the surface heat-reflective function.

The material of the enthalpy-changeable nano-insulation lining 3 is an enthalpy-changeable nano-insulation material, which is composed of high-temperature-resistant nanopowder (one or more of nano-silicon oxide, nano-alumina, and nano-mullite), enthalpy-change material Nanopowder (one or more of aluminum hydroxide, boric acid, hydrated magnesium chloride, calcium carbonate, lithium carbonate), ceramic reinforced fiber (quartz chopped fiber, glass chopped fiber, zirconia fiber, silicon nitride chopped fiber, One or more of mullite fiber, alumina fiber, high silica fiber, basalt fiber, silicon carbide fiber), opacifier powder (silicon carbide powder, titanium oxide powder, zirconium oxide powder, zirconium silicate powder, Composed of one or more of chromium oxide powder and iron oxide powder, the high-temperature resistant nanopowder, enthalpy change nanopowder, sunscreen agent particles, and reinforcing fibers are evenly mixed, and then dry molded to prepare a product with excellent thermal insulation properties. The enthalpy-changeable nano-insulation material is then machined and formed into the enthalpy-changeable nano-insulation lining 3 of the desired shape.

The components and density of the enthalpy-changeable nano thermal insulation lining 3 are determined according to the following method:

S1. Set the initial overall density of the enthalpy-changeable nano-insulation material; the relationship between the initial overall density and the upper limit of the overall density is: ρ ₀ = (0.7 ~ 0.9) ρ _max , the upper limit of the overall density of the enthalpy-changeable nano-insulation material ρ _max is inferred based on the overall weight requirements of the thermal protective sleeve of the flight parameter recorder, and does not exceed the overall density of the thermal protective sleeve of the flight parameter recorder.

S2. Select the enthalpy-changeable material nanopowder according to the temperature-resistant allowable temperature of the protected data chip 5, and select the one with the highest latent enthalpy heating value within the range where the latent enthalpy change temperature is higher than the temperature-resistant allowable temperature of the protected data chip 5. Enthalpy changeable material nanopowder;

S3. According to the preset ratio, prepare a sample of the enthalpy-changeable nano-insulation material so that the density of the enthalpy-changeable nano-insulation material is the initial overall density determined in step S1;

The preset proportions of each component in the enthalpy changeable nano thermal insulation material sample are: the initial addition proportion of enthalpy changeable material nano powder is 20-40wt%, the remaining components are high-temperature nanopowder, accounting for 40-65wt%, ceramic reinforcement The fiber accounts for 5-10wt% and the sunscreen powder accounts for 5-10wt%.

S4. Conduct thermal conductivity testing and differential thermal analysis on the enthalpy-changeable nano-insulation material samples to obtain the actual thermal conductivity, latent enthalpy change temperature point and latent enthalpy heat value of the enthalpy-changeable nano-insulation material;

S5. Based on the actual thermal conductivity, latent enthalpy change temperature point and latent enthalpy heat value of the enthalpy-changeable nano-insulation material sample, use the fire test thermal field simulation process to conduct the fire test thermal field simulation to obtain the protected data chip The temperature of 5 does not exceed the allowable temperature resistance temperature of the enthalpy changeable nano thermal insulation lining 3 thickness;

S6. Determine whether the thickness of the enthalpy-changeable nano thermal insulation lining 3 meets the preset thickness requirements. If it meets the preset thickness requirements, proceed to step S7. If not, increase the proportion of the enthalpy-changeable material and re-execute steps S3 to S6. ;

S7. Conduct actual fire test assessment. If the final temperature Tc,ex of the protected data chip 5 after the fire test is lower than the allowable temperature resistance of the protected data chip 5, then proceed to step S8; if the chip exceeds the allowable temperature resistance of the chip, Compare whether the difference between the final temperature T _{c,ex of} the protected data chip 5 after the fire test and the final temperature T _c of the protected data chip 5 calculated by the simulation in step S5 is lower than the allowable deviation ΔT, if |T _c,ex -T _c |＞ΔT, correct the thermal field environment temperature in the simulation model in step 5, and re-execute steps S5~S7; if |T _c,ex -T _c |＜ΔT, increase the overall density ρ of the enthalpy-changeable nano-insulation material , execute S3 to S7 again until the final temperature of the protected data chip 5 after the fire test is lower than the allowable temperature of the chip.

The breathable channel 4 is in a closed state without fire, and is filled with sealing filler (one or more of silicone rubber, flexible graphite, fluororubber, polytetrafluoroethylene, and synthetic resin). In the fire state, that is, when the temperature of the outer structural shell is higher than the latent enthalpy change temperature point of the enthalpy-changeable nano-insulation material, the sealing filler fails, connects the enthalpy-changeable nano-insulation material and the outside world, discharges gas products, and the outer structural shell The outer surface of the body 2 forms a gas film protective layer, which blocks the high-temperature flame from convection heat transfer to the surface of the outer structural shell 2 .

The outer structural shell 2 is made by a casting process. Mo, Al, Nb, Ta and other strengthening elements are added during the smelting of the steel to form a martensitic precipitation hardening stainless steel. After solid solution and aging treatment, it has both strength and high toughness. . The tensile strength of the outer structural shell 2 is ≥1310MPa and the impact toughness is ≥126J/cm ² .

The heat reflective coating 1 is attached to the surface of the outer structural shell 2, has a thickness of 20-80 μm, a thermal radiation coefficient higher than 0.85, and is resistant to moisture and heat, acid and alkali corrosion and aging.

Preferably, the breathable channel 4 has an internal thread structure, and the breathable channel 4 with built-in sealing material can pass the 0.4MPa/1h airtight sealing test at normal temperature.

Preferably, under the high temperature fire condition of 1100°C, the sealing material in the ventilation channel 4 can be ablated and volatilized within 10 minutes, so that the open area ratio of the ventilation channel 4 is greater than 80%.

Preferably, the density of the enthalpy-changeable nano thermal insulation lining 3 is 0.45-0.8g/cm ³ , the thermal conductivity at room temperature is less than 0.03W/(m·K), the compressive strength is greater than 0.5MPa, and the latent enthalpy absorbs heat Amount>600kJ/kg.

The steps for preparing the enthalpy-changeable nano thermal insulation lining 3 are as follows:

S3.1. Mix and disperse the enthalpy changeable material nanopowder and high temperature resistant nanopowder according to the mass ratio of 2:1;

S3.2. Use a ball mill to grind the dispersed mixed powder to grind the enthalpy changeable material nanopowder to a particle size of less than 800 nm;

S3.3. Mix the ground mixed powder with the remaining high-temperature resistant nanopowder, opacifier powder and ceramic reinforcing fiber;

S3.4. According to the initial overall density of the enthalpy-changeable nano-insulation material, the mixed raw materials are dry-molded to prepare the enthalpy-change nano-insulation material, which is used as the blank of the enthalpy-change nano-insulation lining 3. ;

S3.5. According to the thickness of the enthalpy-changeable nano-insulation lining 3, use a milling machine to prepare the blank of the enthalpy-changeable nano-insulation lining 3. The cutting speed of the milling machine is not less than 5000r/min, and the cutting speed is slow. A space for assembling the inner sealing housing 7 is created.

The specific manufacturing examples and steps of the flight parameter recorder thermal protective sleeve are as follows:

Example 1:

step one:

Make enthalpy changeable nano thermal insulation lining 3, the details are as follows:

According to the above method, determine the thermal conductivity and density of the required enthalpy-changeable nano-insulation material.

Preparation of enthalpy-changeable nano-insulation materials based on material density. Weigh 240g of enthalpy changeable material powder and 120g of nanometer silicon oxide powder, mix and disperse them, and then use a ball mill to grind the dispersed mixed powder so that the enthalpy changeable material powder is ground to a particle size of less than 800 nm. The mixture of the ground enthalpy change material and nano-silica was mixed with 195 g of nano-silica powder, 61 g of opacifier powder and 50 g of ceramic reinforcing fibers. According to the required density, the mixed raw materials are molded to prepare the enthalpy-changeable nano-insulation material, which is used as the blank of the enthalpy-change nano-insulation lining 3.

The properties of the prepared enthalpy-changeable nano-insulation material are: thermal conductivity 0.0246W/(m·K), latent enthalpy change temperature 200-260°C, and latent enthalpy variable 680J/kg.

The blank of the enthalpy-changeable nano thermal insulation lining 3 is prepared by using a milling machine. The cutting speed of the milling machine is not less than 5000 r/min. The cutting speed is slow and the space for assembling the inner sealing shell 7 is milled out. After the processing is completed, the cutting surface of the enthalpy-changeable nano-insulation lining 3 is uniform and has no obvious pits or cracks.

Step 2:

The outer structural shell 2 and the heat reflective coating 1 are produced, as follows:

The outer structural shell 2 is made using a casting process or a 3D printing method, and the material is one of high temperature resistant martensitic steel, high temperature resistant austenitic steel, and high temperature resistant titanium alloy. The tensile strength of the outer structural shell 2 is ≥1310MPa, and the impact toughness is ≥126J/cm ² . The outer structural shell 2 can also be replaced by materials such as high-temperature alloys that meet strength and toughness requirements.

The heat reflective coating 1 is made on the outer surface of the outer structural shell 2, and the making method refers to Chinese patent CN106228636. The total thickness of the coating is 20-80 μm, and it is dried at room temperature and cured for 24 hours. After curing, the thermal radiation coefficient of the heat reflective coating is greater than 0.85, and the color is gray.

A high-temperature ventilation channel 4 is made on the outer structural shell 2, and the processing method is rotary drilling. The high-temperature breathable channel 4 is a through hole with a diameter of 2.5mm and a threaded structure inside. The inner side of the through hole is connected to the enthalpy changeable nano thermal insulation lining 3, and the outer side is connected to the external environment. The inside of the machined through hole is filled with epoxy sealant. The epoxy resin is poured by vacuuming. After the infusion is completed, it is allowed to stand for 4 hours at normal temperature and pressure to solidify. Under normal temperature, the high-temperature breathable channel 4 remains sealed and can pass the 0.4MPa/24h airtight sealing test assessment. Under high-temperature fire conditions of 1100°C, the sealing material in the high-temperature breathable channel 4 can be ablated and volatilized within 10 minutes, and the open area ratio is greater than 80%.

Step three:

Make the inner sealing case 7 and install the data chip 5 . The material of the inner sealing shell 7 is one of stainless steel, titanium alloy, and aluminum alloy, and is divided into two parts: the inner sealing shell bottom cover and the inner sealing shell bottom cover tank body. The data chip 5 is first encapsulated in an insulating silicone sealing material, and then installed at the center of the inner sealing case bottom cover, and then the inner sealing case bottom cover is connected to the inner sealing case can. The connection method is a threaded sealing connection, and insulating silicone is applied to the connection seam for further sealing. Sampling 5% of the inner sealing shells 7 of a batch from the total number, conduct a 60MPa/30d watertight sealing test to observe whether water penetrates into the tank interior. After passing the sealing standard, it can be installed inside the flight parameter recorder.

Example 2:

step one:

Make enthalpy changeable nano thermal insulation lining 3, the details are as follows:

According to the above analysis method, determine the thermal conductivity and density of the required enthalpy-changeable nano-insulation material.

Preparation of enthalpy-changeable nano-insulation materials based on material density. Weigh 180g of enthalpy change material powder and 90g of nano-alumina powder, mix and disperse them, and then use a ball mill to grind the dispersed mixed powder so that the enthalpy change material powder can be ground to a particle size of less than 800 nm. The mixture of the ground enthalpy change material and nano-silica was mixed with 260 g of nano-alumina powder, 59 g of opacifier powder and 55 g of ceramic reinforcing fibers. According to the required density, the mixed raw materials are molded to prepare the enthalpy-changeable nano-insulation material, which is used as the blank of the enthalpy-change nano-insulation lining 3.

The properties of the prepared enthalpy-changeable nano-insulation material are: thermal conductivity 0.0248W/(m·K), latent enthalpy change temperature 110-180°C, and latent enthalpy variable 750kJ/kg.

The blank of the enthalpy-changeable nano thermal insulation lining 3 is prepared by using a milling machine. The cutting speed of the milling machine is not less than 5000 r/min. The cutting speed is slow and the space for assembling the inner sealing shell 7 is milled out. After the processing is completed, the cutting surface of the enthalpy-changeable nano-insulation lining 3 is uniform and has no obvious pits or cracks.

Step two:

The outer structural shell 2 and the heat reflective coating 1 are produced, as follows:

The outer structural shell 2 is made using a casting process or a 3D printing method, and the material is one of high temperature resistant martensitic steel, high temperature resistant austenitic steel, and high temperature resistant titanium alloy. The tensile strength of the outer structural shell 2 is ≥1310MPa, and the impact toughness is ≥126J/cm ² . The outer structural shell 2 can also be replaced by materials such as high-temperature alloys that meet strength and toughness requirements.

The heat reflective coating 1 is made on the outer surface of the outer structural shell 2, and the making method refers to Chinese patent CN106228636. The total thickness of the coating is 20-80 μm, and it is dried at room temperature and cured for 24 hours. After curing, the thermal radiation coefficient of the heat reflective coating is greater than 0.85, and the color is gray.

A high-temperature ventilation channel 4 is made on the outer structural shell 2, and the processing method is rotary drilling. The high-temperature breathable channel 4 is a through hole with a diameter of 2.5mm and a threaded structure inside. The inner side of the through hole is connected to the enthalpy changeable nano thermal insulation lining 3, and the outer side is connected to the external environment. Pour room temperature vulcanized silicone rubber sealing material inside the machined through hole. Room temperature vulcanized silicone rubber is poured by vacuuming. After the filling is completed, it is vulcanized at normal temperature and pressure. After vulcanization for 4 hours, it solidifies. Under normal temperature, the high-temperature breathable channel 4 remains sealed and can pass the 0.4MPa/24h airtight sealing test assessment. Under high-temperature fire conditions of 1100°C, the sealing material in the high-temperature breathable channel 4 can be ablated and volatilized within 10 minutes, and the open area ratio is greater than 70%.

Step three:

Make the inner sealing case 7 and install the data chip 5 . The material of the inner sealing shell 7 is one of stainless steel, titanium alloy, and aluminum alloy, and is divided into two parts: the inner sealing shell bottom cover and the inner sealing shell bottom cover tank body. The data chip 5 is first encapsulated in an insulating silicone sealing material, and then installed at the center of the inner sealing case bottom cover, and then the inner sealing case bottom cover is connected to the inner sealing case can. The connection method is a threaded sealing connection, and insulating silicone is applied to the connection seam for further sealing. Sampling 5% of the inner sealing shells 7 of a batch from the total number, conduct a 60MPa/30d watertight sealing test to observe whether water penetrates into the tank interior. After passing the sealing standard, it can be installed inside the flight parameter recorder.

Example 3:

step one:

Make enthalpy changeable nano thermal insulation lining 3, the details are as follows:

According to the above analysis method, determine the thermal conductivity and density of the required enthalpy-changeable nano-insulation material.

Preparation of enthalpy-changeable nano-insulation materials based on material density. Weigh 155g of enthalpy changeable material powder and 80g of nano-alumina powder, mix and disperse them, and then use a ball mill to grind the dispersed mixed powder so that the enthalpy changeable material powder is ground to a particle size of less than 900 nm. The mixture of the ground enthalpy change material and nano-silica was mixed with 320 g of nano-alumina powder, 59 g of opacifier powder and 52 g of ceramic reinforcing fibers. According to the required density, the mixed raw materials are molded to prepare the enthalpy-changeable nano-insulation material, which is used as the blank of the enthalpy-change nano-insulation lining 3.

The properties of the prepared enthalpy-changeable nano-insulation material are: thermal conductivity 0.0247W/(m·K), latent enthalpy change temperature 116-240°C, and latent enthalpy variable 755kJ/kg.

The blank of the enthalpy-changeable nano thermal insulation lining 3 is prepared by using a milling machine. The cutting speed of the milling machine is not less than 5000 r/min. The cutting speed is slow and the space for assembling the inner sealing shell 7 is milled out. After the processing is completed, the cutting surface of the enthalpy-changeable nano-insulation lining 3 is uniform and has no obvious pits or cracks.

Step two:

The outer structural shell 2 and the heat reflective coating 1 are produced, as follows:

The outer structural shell 2 is made using a casting process or a 3D printing method, and the material is one of high temperature resistant martensitic steel, high temperature resistant austenitic steel, and high temperature resistant titanium alloy. The tensile strength of the outer structural shell 2 is ≥1310MPa, and the impact toughness is ≥126J/cm ² . The outer structural shell 2 can also be replaced by materials such as high-temperature alloys that meet strength and toughness requirements.

The heat reflective coating 1 is made on the outer surface of the outer structural shell 2, and the making method refers to Chinese patent CN106228636. The total thickness of the coating is 20-80 μm, and it is dried at room temperature and cured for 24 hours. After curing, the thermal radiation coefficient of the heat reflective coating is greater than 0.85, and the color is gray.

A high-temperature ventilation channel 4 is made on the outer structural shell 2, and the processing method is rotary drilling. The high-temperature breathable channel 4 is a through hole with a diameter of 2.5mm and a threaded structure inside. The inner side of the through hole is connected to the enthalpy changeable nano thermal insulation lining 3, and the outer side is connected to the external environment. Pour room temperature vulcanized silicone rubber sealing material inside the machined through hole. Room temperature vulcanized silicone rubber is poured by vacuuming. After the filling is completed, it is vulcanized at normal temperature and pressure. After vulcanization for 4 hours, it is cured and formed. Under normal temperature, the high-temperature breathable channel 4 remains sealed and can pass the 0.4MPa/24h airtight sealing test assessment. Under high-temperature fire conditions of 1100°C, the sealing material in the high-temperature breathable channel 4 can be ablated and volatilized within 10 minutes, and the open area ratio is greater than 70%.

Step three:

Make the inner sealing case 7 and install the data chip 5 . The material of the inner sealing shell 7 is one of stainless steel, titanium alloy, and aluminum alloy, and is divided into two parts: the inner sealing shell bottom cover and the inner sealing shell bottom cover tank body. The data chip 5 is first encapsulated in an insulating silicone sealing material, and then installed at the center of the inner sealing case bottom cover, and then the inner sealing case bottom cover is connected to the inner sealing case can. The connection method is a threaded sealing connection, and insulating silicone is applied to the connection seam for further sealing. Sampling 5% of the inner sealing shells 7 of a batch from the total number, conduct a 60MPa/30d watertight sealing test to observe whether water penetrates into the tank interior. After passing the sealing standard, it can be installed inside the flight parameter recorder.

To sum up, the flight parameter recorder of the present invention uses nano-insulation materials with enthalpy changeable components to construct a heat insulation/change absorption integrated flight parameter recorder thermal protective sleeve. Nano thermal insulation materials have excellent thermal insulation properties, with thermal conductivity as low as 0.03W/(m·K). They are combined with nano-sized enthalpy changeable materials to form thermal insulation/heat absorption integrated thermal insulation materials. The made thermal protective sleeve of the flight parameter recorder can have both thermal insulation performance and high enthalpy heat absorption performance. At the same time, the enthalpy change process is a solid-gas change process, and the latent enthalpy heat absorption is >600kJ/kg, and it can be released after absorbing heat. The gas product forms a heat-insulating air film on the surface of the flight parameter recorder, slowing down the convective heat transfer from the flame to the flight parameter recorder. The thermal protection structure of the flight parameter recorder can improve the thermal protection performance of the flight parameter recorder while making the structure of the flight parameter recorder more compact, thereby minimizing the overall volume and weight.

The above are only the best specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technical field can easily think of changes or modifications within the technical scope disclosed in the present invention. All substitutions are within the scope of the present invention.

Contents not described in detail in the specification of the present invention belong to the well-known techniques of those skilled in the art.

Claims (8)

1. The heat protection sleeve for the flight parameter recorder based on the enthalpy-variable nano heat insulation material is characterized by comprising an enthalpy-variable nano heat insulation lining (3), an outer structure shell (2), a heat reflection coating (1), an inner sealing shell (7), inner sealing fillers (6) and N ventilation channels (4), wherein N is more than or equal to 1;

the enthalpy-variable nano heat insulation lining (3) is arranged in the outer structure shell (2), and the outer side of the inner sealing shell (7) is in direct contact with the inner structure shell and the outer structure shell; the inner sealing shell (7), the protected data chip (5) and the sealing filler (6) are all positioned inside the enthalpy-variable nano heat insulation lining (3), the protected data chip (5) is arranged at the center of the inner sealing shell (7), and the sealing filler (6) is filled between the protected data chip (5) and the inner sealing shell (7); each ventilation channel (4) is arranged in the structure of the outer structure shell (2), the inner opening of each ventilation channel (4) is in contact with the enthalpy-variable nano heat insulation lining (3), the outer opening is in contact with the outside, the ventilation channels (4) are filled with sealing materials, and the sealing materials are used for airtight sealing at normal temperature; in a burning state, the enthalpy-variable nano heat insulation lining (3) has heat insulation and enthalpy-variable heat absorption effects, a gaseous product after the enthalpy change forms a gas film on the surface of the outer structure shell (2) of the flight parameter recorder, the convection heat transfer of flame to the flight parameter recorder is slowed down, the sealing filler (6) is used for preventing the gaseous product from penetrating into the inner sealing shell (7) to be contacted with the protected data chip (5), and the sealing material in the ventilation channel (4) is ablated and volatilized, so that the ventilation channel (4) is communicated with the external space and the enthalpy-variable nano heat insulation lining (3);

the enthalpy-variable nano heat insulation lining (3) is made of an enthalpy-variable nano heat insulation material and consists of high-temperature resistant nano powder, enthalpy-variable material nano powder, ceramic reinforcing fibers and opacifier powder, wherein the high-temperature resistant nano powder is one or more of nano silicon oxide, nano aluminum oxide and nano mullite; the enthalpy-variable material nano powder is one or more of aluminum hydroxide, boric acid, hydrated magnesium chloride, calcium carbonate and lithium carbonate, the ceramic reinforcing fiber is one or more of quartz chopped fiber, glass chopped fiber, zirconia fiber, silicon nitride chopped fiber, mullite fiber, alumina fiber, high silica fiber, basalt fiber and silicon carbide fiber, and the opacifier powder is one or more of silicon carbide powder, titanium oxide powder, zirconium silicate powder, chromium oxide powder and ferric oxide powder;

the preparation method of the enthalpy-variable nanometer heat insulation lining (3) comprises the following steps:

the enthalpy-variable material nano powder and the high temperature resistant nano powder are mixed according to the mass ratio of 2:1, mixing and dispersing;

grinding the dispersed mixed powder by using a ball mill to grind the enthalpy-variable material nano powder therein to a particle size below 800 nm;

mixing the ground mixed powder with the rest of high-temperature resistant nano powder, opacifier powder and ceramic reinforced fiber;

according to the initial overall density of the enthalpy-variable nano heat-insulating material, performing dry compression molding on the mixed raw materials to prepare the enthalpy-variable nano heat-insulating material serving as a blank of the enthalpy-variable nano heat-insulating lining (3);

and milling a blank of the enthalpy-changing nano heat-insulating lining (3) prepared by milling according to the thickness of the enthalpy-changing nano heat-insulating lining (3) to form a shape for assembling the inner sealing shell (7).

2. The flight parameter recorder thermal protection sleeve based on the enthalpy change nanometer heat insulation material according to claim 1, wherein the flight parameter recorder thermal protection sleeve comprises: the ventilation channel (4) is provided with an internal thread structure.

3. The flight parameter recorder thermal protection sleeve based on the enthalpy change nanometer heat insulation material according to claim 1, wherein the flight parameter recorder thermal protection sleeve comprises: the ventilation channel (4) with the built-in sealing material can be checked by a 0.4MPa/1h airtight sealing test at normal temperature.

4. The flight parameter recorder thermal protection sleeve based on the enthalpy change nanometer heat insulation material according to claim 1, wherein the flight parameter recorder thermal protection sleeve comprises: under the condition of high-temperature fire at 1100 ℃, the sealing material in the ventilation channel (4) can be ablated and volatilized within 10min, so that the proportion of the open pore area of the ventilation channel (4) is more than 80%.

5. A flight parameter recorder thermal protection cover based on nano heat insulation material capable of changing enthalpy according to any one of claims 1-3, characterized in that the density of the nano heat insulation lining (3) capable of changing enthalpy is 0.45-0.8 g/cm ³ The heat conductivity at normal temperature is less than 0.03W/(m.K), the compressive strength is more than 0.5MPa, and the latent enthalpy absorbs heat>600kJ/kg。

6. A flight parameter recorder thermal protection sleeve based on nano-heat insulation material with variable enthalpy, according to claim 5, characterized in that the composition of the nano-heat insulation lining (3) with variable enthalpy and its density are determined according to the following method:

s1, setting the initial overall density of the enthalpy-variable nano heat insulation material;

s2, selecting nano powder of the enthalpy change material according to the temperature resistant allowable temperature of the protected data chip (5), and selecting nano powder of the enthalpy change material with the highest latent enthalpy heat value in a range that the latent enthalpy temperature change is higher than the temperature resistant allowable temperature of the protected data chip (5);

s3, preparing an enthalpy-variable nano heat-insulating material sample according to a preset proportion so that the density of the enthalpy-variable nano heat-insulating material is the initial overall density determined in the step S1;

s4, performing heat conductivity test and differential thermal analysis on the enthalpy-variable nano heat-insulating material sample piece to obtain the actual heat conductivity, latent enthalpy change temperature point and latent enthalpy heat value of the enthalpy-variable nano heat-insulating material;

s5, performing fire test thermal field simulation according to the actual heat conductivity, the latent enthalpy change temperature point and the latent enthalpy heat value of the enthalpy change nano heat insulation material sample piece by adopting a fire test thermal field simulation flow to obtain the thickness of the enthalpy change nano heat insulation lining (3) which enables the temperature of the protected data chip (5) not to exceed the temperature tolerance allowable temperature;

s6, judging whether the thickness of the enthalpy-variable nano heat insulation lining (3) meets the preset thickness requirement, if so, entering a step S7, and if not, increasing the addition proportion of the enthalpy-variable material, and re-executing the steps S3-S6;

s7, performing actual fire test examination, and if the final temperature Tc and ex of the protected data chip (5) after the fire test is lower than the temperature tolerance allowable temperature of the protected data chip (5), entering a step S8; if the chip exceeds the chip temperature tolerance allowable temperature, comparing the final temperature T of the protected data chip (5) after the fire test _c,ex And the final temperature T of the protected data chip (5) obtained by simulation calculation in the step S5 _c If the difference is lower than the allowable deviation DeltaT, if DeltaT _c,ex -T _c Correcting the environmental temperature of the thermal field in the simulation model in the step (5) and re-executing the steps S5 to S7; if |T _c,ex -T _c And (3) increasing the integral density rho of the enthalpy-variable nano heat-insulating material until the whole density rho is less than delta T, and re-executing S3-S7 until the whole density rho is protected after a fire testThe final temperature of the data chip (5) is lower than the chip temperature tolerance temperature.

7. The thermal protection sleeve for a flight parameter recorder based on an enthalpy change nano heat insulating material according to claim 6, wherein the relation between the initial bulk density and the bulk density upper limit is: ρ ₀ ＝(0.7～0.9)ρ _max Bulk density upper limit ρ of enthalpy-variable nano heat insulating material _max And deducing according to the overall weight requirement of the thermal protection sleeve of the flight parameter recorder, wherein the overall density of the thermal protection sleeve of the flight parameter recorder is not exceeded.

8. The thermal protection sleeve for the flight parameter recorder based on the nano heat insulation material capable of changing enthalpy according to claim 6, wherein the preset proportion of each component in the nano heat insulation material sample capable of changing enthalpy in the step S3 is as follows: the initial addition proportion of the enthalpy-variable material nano powder is 20-40 wt%, the rest components are high-temperature nano powder, the proportion is 40-65 wt%, the proportion of the ceramic reinforcing fiber is 5-10 wt% and the proportion of the opacifier powder is 5-10 wt%.