Hourglass type steam micro-thruster nozzle

Abstract

The invention belongs to the technical field of micro-nano electronic devices, and particularly relates to an hourglass type steam micro-thruster nozzle. Comprising an inlet cavity, an outlet cavity and a communicating hole communicating the inlet cavity with the outlet cavity, the inlet cavity and the outlet cavity are each of a trumpet-shaped structure, the diameter of the inlet cavity is gradually reduced to the communicating hole from an inlet, and the wall of the inlet cavity is sequentially composed of a heating layer, an insulating silicon oxide layer and a silicon substrate layer from inside to outside; the diameter of the outlet cavity is gradually increased from the communicating hole to the outlet, and the wall of the outlet cavity is sequentially composed of an insulating silicon oxide layer and a silicon substrate layer from inside to outside. A micro-nano-scale metal film is adopted as a heating layer on the cavity wall of an inlet cavity, and the micro-nano-scale metal film and the inlet cavity with the diameter gradually reduced from an inlet to a communicating hole act together to control vacuum boiling of deionized water so as to generate micro-Newton-scale thrust. The device has the advantages of being high in integration level, low in power consumption and micro in impulse, and thrust generated by the device is at the micro-Newton level.

Description

Technical Field

[0001] The invention belongs to the technical field of micro-nano electronic devices, and in particular relates to an hourglass-shaped steam micro-thruster nozzle. Background Art

[0002] The thrust system is an indispensable and important part of aerospace satellites. In recent years, with the continuous advancement of micro-satellite technology, the trend of satellite development has undergone profound changes, gradually shifting from traditional multi-functional integration to distributed, multi-satellite collaborative formation of small satellite networking mode. In this context of transformation, it is not feasible to directly copy and transplant the thrust system of large satellites into micro-satellite systems. For the thrust system that micro-satellites rely on for orbital operation, the required thrust level is very different from that when launched from the ground. Given that micro-satellites are in a vacuum working environment, when performing satellite attitude control, only extremely weak thrust is sufficient to achieve effective control of the overall attitude of the satellite. At the same time, micro-satellites have strict requirements on the volume ratio of the thrust system, which must be miniaturized and lightweight, which undoubtedly puts extremely stringent standards and challenges on the micro-thrust system.

[0003] The microthruster nozzle is the core and key part of the microthrust system. Compared with the traditional large satellite thruster nozzle, the microthruster nozzle built with the help of micro-electromechanical (MEMS) technology has many advantages, such as greatly shortened R&D cycle, significantly reduced cost, extremely wide application range, good scalability, etc. For this reason, it has become a focus of attention in the aerospace research in recent years. Considering the distinctive characteristics of micro-satellites, such as small size, light weight, and small moment of inertia, the nozzles they carry usually need to have special properties such as stable and precise control, high integration, low power consumption, small thrust and micro impulse, and the thrust level generated by the nozzle is in the micro-newton level. However, it is undoubtedly a difficult and challenging task to accurately reduce the existing thrust system to such a low level. Therefore, in-depth research on microthruster nozzles has a very critical driving role and far-reaching significance for building a more energy-saving, environmentally friendly, low-cost, high-quality, and efficient thrust system. Summary of the invention

[0004] The object of the present invention is to provide an hourglass-type steam micro-thruster nozzle, which has the characteristics of high integration, low power consumption, and micro-impulse, and the thrust generated by the nozzle is at the micro-Newton level.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] An hourglass-shaped steam micro-thruster nozzle comprises an inlet chamber, an outlet chamber, and a connecting hole connecting the inlet chamber and the outlet chamber, wherein the inlet chamber and the outlet chamber both adopt a trumpet-shaped structure, wherein:

[0007] The diameter of the inlet chamber gradually decreases from the entrance to the communicating hole, and the inlet chamber wall is composed of a heating layer, an insulating silicon oxide layer and a base layer from the inside to the outside;

[0008] The diameter of the outlet chamber gradually increases from the communicating hole to the outlet, and the wall of the outlet chamber is composed of an insulating silicon oxide layer and a base layer from the inside to the outside.

[0009] Furthermore, when the nozzle is in a non-eruption state, the deionized water is stationary in the inlet chamber due to surface tension, and at this time, the heating layer is in a non-conduction state; when the heating layer receives a high-level pulse signal applied from the outside, the heating layer is turned on and generates heat, and the deionized water absorbs the heat provided by the heating layer, so that the vapor pressure is increased until it breaks through the surface tension, vacuum boiling, vaporization and expansion occur, and then it is ejected through the outlet chamber, thereby generating thrust.

[0010] Furthermore, the heating layer is a micro-nano-scale metal film.

[0011] Furthermore, the heating layer material includes polymer composite materials, metal alloys, non-metallic heating materials, and ceramic materials; wherein the metal alloys include nickel alloys and nickel-chromium alloys, and the non-metallic heating materials include carbon nanotubes and graphite.

[0012] Furthermore, the substrate layer material of the nozzle inlet cavity and the outlet cavity includes semiconductor conductive materials such as silicon, germanium, gallium arsenide, and indium arsenide.

[0013] Furthermore, along the plasma water spraying direction, the ratio of the inlet chamber length to the outlet chamber length is in the range of:

[0014] The beneficial effects of the present invention are: by using a micro-nano metal film as a heating layer on the chamber wall of the inlet chamber, and working together with the inlet chamber whose diameter gradually decreases from the inlet to the connecting hole, the vacuum boiling of deionized water is controlled to achieve micro-Newton thrust generation, and the control process is energy-free and simple and easy to implement. In addition, the overall area of ​​the nozzle of the present invention does not exceed 3 square centimeters, and the mass does not exceed 1 gram, which is suitable for existing micro-propulsion systems and has a promoting effect on their improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the hourglass-shaped steam micro-thruster nozzle structure of the embodiment;

[0016] Figure 2It is a schematic diagram of deionized water distribution in the hourglass-shaped steam micro-thruster nozzle of the embodiment when it is not spraying;

[0017] Figure 3 It is a schematic diagram of deionized water distribution in the spraying state of the hourglass-shaped steam micro-thruster nozzle of the embodiment;

[0018] Figure 4 SEM image of hourglass-shaped steam micro-thruster nozzle Figure 1 ;

[0019] Figure 5 SEM image of hourglass-shaped steam micro-thruster nozzle Figure 2 ;

[0020] Reference numerals:

[0021] 1 is a silicon oxide insulating layer, 2 is a silicon base layer, 3 is a heating layer, 4 is deionized water, and 5 is a liquid-gas mixture of deionized water. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings and embodiments.

[0023] like Figure 1 As shown, an hourglass-shaped steam micro-thruster nozzle includes an inlet chamber and an outlet chamber connected to the inlet chamber. Both the inlet chamber and the outlet chamber adopt a trumpet-shaped structure, wherein: the diameter of the inlet chamber gradually decreases from the inlet to the connecting hole, and the inlet chamber wall is composed of a heating layer, an insulating silicon oxide layer and a silicon base layer from the inside to the outside; the diameter of the outlet chamber gradually increases from the connecting hole to the outlet, and the outlet chamber wall is composed of an insulating silicon oxide layer and a silicon base layer from the inside to the outside.

[0024] In this embodiment, the inlet chamber wall uses a micro-nano metal film as a heat-generating layer, which together with the inlet chamber whose diameter gradually decreases from the inlet to the connecting hole constitutes a thermal valve control system. Figure 2-Figure 3 As shown, when deionized water enters the inlet chamber, the high-level pulse signal provided by the outside drives the heating layer film to heat up. At this time, the deionized water absorbs the heat provided by the heating layer, so that the vapor pressure is increased until it breaks through the surface tension, vacuum boiling, vaporization and expansion occur, and then it is ejected through the outlet chamber, thereby generating a micro-thrust of 18μN-500μN.

[0025] In order to ensure the normal working state of the nozzle, it is necessary to control the influence of the ratio between the length L1 of the nozzle inlet chamber and the length L2 of the nozzle outlet chamber on the plasma water injection and the flow inside the tube body. When the ratio is less than 0.052, the plasma water in the nozzle inlet chamber cannot break through the surface tension and spray out smoothly. When the ratio is greater than 0.37, there will be too much plasma water in the nozzle inlet chamber, resulting in unstable flow of the gas-liquid mixture during the eruption, which will have a greater impact on the side wall of the nozzle. In severe cases, it may cause the entire nozzle to rupture, causing it to fail completely. In view of this, the ratio range of the inlet chamber length L1 and the outlet chamber length L2 along the direction of plasma water spraying is set to It is particularly important, as it can effectively adjust the water flow conditions at the nozzle inlet chamber, avoid various problems caused by inappropriate length of the nozzle inlet chamber, and maintain stable operation of the nozzle.

[0026] The preparation process of the hourglass-shaped steam micro-thruster nozzle is as follows:

[0027] Step 1: Silicon wafer selection and cleaning:

[0028] This embodiment uses an N-type lightly doped silicon wafer with a resistivity of about 3-25Ω / cm-3 and a crystal orientation of 100. After ultrasonic cleaning with deionized water, the surface oil is removed with an acetone solution, and then the residual acetone is removed with an ethanol solution, and finally ultrasonic cleaning with deionized water is performed and then dried.

[0029] Step 2: Place the silicon wafer obtained in step 1 into a tube furnace, set the oxygen flow rate to 0.5 sccm, and set the temperature to 1000 degrees Celsius for thermal oxidation to form a silicon oxide insulating layer.

[0030] Step 3: Make the nozzle inlet cavity structure:

[0031] 1) Using photolithography technology, after the steps of coating, pre-baking, exposure, development, and post-baking, an inlet photoresist pattern is made on the silicon oxide insulating layer on the inlet surface of the silicon wafer obtained in step 2, and then the pattern is transferred to the surface of the silicon oxide insulating layer using a silicon oxide buffered etching solution to form a silicon oxide window. Next, an acetone solution is used to remove the remaining photoresist, and then an ethanol solution is used to remove the residual acetone. After that, ultrasonic cleaning with deionized water and drying are performed.

[0032] 2) A mixed solution of 25% tetramethylammonium hydroxide and 10% isopropanol in a ratio of 1:1 was used as a wet etching solution to anisotropically etch the silicon in the silicon oxide window to obtain an inlet chamber structure. In order to enhance the binding effect on the surface tension of the plasma water and better control the nozzle spraying state, the inlet chamber of this embodiment adopts a V-shaped structure.

[0033] Step 3: Wash and dry the structure obtained in step 2 with deionized water, place it in a tube furnace for thermal oxidation treatment again, then evenly apply photoresist on the inlet surface of the silicon wafer and dry it, and then use plasma etching technology to thin the photoresist, leaving only the required photoresist thickness in the V-groove.

[0034] Step 4: Use electron beam evaporation to deposit a layer of nickel-chromium alloy as a heating layer on the inlet chamber wall of the structure obtained in step 3, and then place it in an acetone solution to remove the photoresist remaining at the bottom of the V-groove in step 3 and the nickel-chromium alloy heating layer covering the photoresist at the bottom of the V-groove, leaving only the nickel-chromium alloy heating layer on the side wall of the V-groove.

[0035] Step 5: Make the nozzle outlet structure

[0036] Using photolithography technology, the steps of photoresist coating, pre-baking, exposure, development and post-baking are carried out in sequence to produce an outlet cavity pattern on the outlet surface of the silicon wafer. Subsequently, a silicon oxide buffered etching solution is used to transfer the pattern to the silicon oxide surface to form a silicon oxide window. Next, an acetone solution is used to remove the remaining photoresist, and then an ethanol solution is used to remove the residual acetone. After that, ultrasonic cleaning is performed with deionized water, and drying is performed after cleaning. Finally, anisotropic etching is performed on the silicon in the silicon oxide window to produce an outlet cavity structure, which is the same as the inlet cavity structure. After the etching is penetrated, it is washed and re-thermal oxidation treatment is performed to obtain the following Figure 4-Figure 5 The hourglass-shaped steam microthruster nozzle is shown.

[0037] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. An hourglass-shaped steam micro-thruster nozzle, comprising an inlet chamber, an outlet chamber, and a connecting hole connecting the inlet chamber and the outlet chamber, wherein both the inlet chamber and the outlet chamber adopt a trumpet-shaped structure, and characterized in that: The diameter of the inlet chamber gradually decreases from the inlet to the communicating hole, and the inlet chamber wall is composed of a heating layer, an insulating silicon oxide layer and a base layer from the inside to the outside; The diameter of the outlet chamber gradually increases from the communicating hole to the outlet, and the wall of the outlet chamber is composed of an insulating silicon oxide layer and a base layer in sequence from the inside to the outside.

2. The hourglass-shaped steam micro-thruster nozzle according to claim 1, characterized in that: When the heating layer receives a high-level pulse signal applied from the outside, the heating layer conducts and generates heat. The deionized water absorbs the heat provided by the heating layer, increasing the vapor pressure until it breaks through the surface tension, causing vacuum boiling, vaporization and expansion, and then it is ejected through the outlet mouth, thereby generating thrust.

3. The hourglass-shaped steam micro-thruster nozzle according to claim 1, characterized in that: The heating layer is a micro-nano metal film.

4. The hourglass-shaped steam micro-thruster nozzle according to claim 3, characterized in that: The heating layer material includes polymer composite materials, metal alloys, non-metal heating materials, and ceramic materials; wherein the metal alloys include nickel alloys and nickel-chromium alloys, and the non-metal heating materials include carbon nanotubes and graphite.

5. The hourglass-shaped steam micro-thruster nozzle according to claim 1, characterized in that: The substrate layer materials of the nozzle inlet cavity and the outlet cavity include semiconductor conductive materials such as silicon, germanium, gallium arsenide, and indium arsenide.

6. An hourglass-shaped steam micro-thruster nozzle according to any one of claims 1 to 5, characterized in that: Along the direction of plasma water spraying, the ratio of the inlet chamber length to the outlet chamber length is as follows:

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