Complex special-shaped part anti-coking film layer and preparation method and preparation system thereof

Abstract

The invention discloses an anti-coking film layer of a complex special-shaped component and a preparation method and a preparation system.The preparation method comprises the steps that the complex special-shaped component is arranged in a reaction cavity of an atomic layer deposition system, a titanium source precursor is injected into the reaction cavity, and then inert gas is introduced to wash the reaction precursor and by-products; injecting an oxygen source precursor into the reaction cavity; finally, inert carrier gas is introduced for flushing; and the deposition step is repeated until the film layer with the required thickness is obtained, and the anti-coking film layer is obtained. The prepared anatase crystal type TiO2 anti-coking film layer can prevent carbon elements from permeating into matrixes made of different materials, the catalytic action of active sites of the matrixes is reduced, the service life of complex parts of a combustion chamber is remarkably prolonged, and the performance of the complex parts of the combustion chamber in an extreme environment is improved.

Description

Technical Field

[0001] The present invention belongs to the field of surface engineering technology, and relates to the passivation of working surfaces of complex and special-shaped parts of combustion chambers (including injectors, cylinder heads, etc.) and high-temperature anti-coking protection, and specifically to an anti-coking film layer for complex and special-shaped parts and a preparation method and system. Background Art

[0002] The combustion chamber is a key area in the engine where fuel and air are mixed and burned to generate power. The combustion chamber components include cylinder liners, pistons, piston rings, cylinder heads, valves, etc. These components need to withstand high temperatures, high pressures and highly corrosive environments, and their performance directly affects the efficiency and operating reliability of the engine.

[0003] Fuel is mainly composed of hydrocarbons, including alkanes, cycloalkanes and aromatic hydrocarbons. If these components are not mixed evenly or the combustion conditions are insufficient during the combustion process, incomplete combustion is likely to occur, generating incompletely oxidized hydrocarbons. In particular, fuels containing more heavy hydrocarbons or high-boiling point components are difficult to completely decompose at high temperatures, and are likely to remain and adhere to the combustion chamber wall or intake valve, forming carbon deposits. In addition, low-quality fuels may contain impurities or inferior additives that are not easily volatile, and the residues generated after combustion will also promote the formation of carbon deposits. When the proportion of aromatic hydrocarbons in the fuel is high, the combustion efficiency will be further reduced, and unburned carbides under high temperature conditions are more likely to be deposited in the injector or combustion chamber, causing the carbon deposit problem to worsen.

[0004] For film layer processes, physical vapor deposition (PVD) technology mainly relies on target sputtering. The sputtered particles move in a straight line and are mainly deposited on the outer surface of complex structural parts, making it difficult to evenly cover the inner surface. Chemical vapor deposition (CVD) technology is based on gaseous precursors. Some precursors can diffuse into the internal channels of complex structures to form thin films. However, the deposition temperature of this method is about 1000°C, which exceeds the heat treatment temperature of most metal materials and is likely to damage the properties of the base material.

[0005] Currently, most atomic layer deposition systems can only coat the inner wall of the pipe. They are still unable to solve the deposition problem on the inner and outer surfaces of large-sized, complex and special-shaped parts with narrow space and complex shapes such as combustion chambers. In addition, the deposition quality such as film uniformity cannot meet the extreme coupled working conditions such as thermal force in the engine combustion chamber.

[0006] There are two technical difficulties in developing an atomic layer deposition (ALD) system for a large chamber, which mainly involve hardware equipment design and built-in system stability. On the one hand, as the chamber size increases, the precursor gas is unevenly distributed on the sample surface, resulting in insufficient precursor concentration in local areas of the component, which affects the deposition rate and film uniformity. On the one hand, the uniformity of substrate heating in a large chamber is difficult to ensure. The ALD process usually requires an operating temperature of 150-400°C. If the chamber is too large, uneven heat conduction will cause local temperature gradients, which will affect the quality of the film. On the other hand, when expanding from a small chamber to a large chamber, it is necessary to solve the nonlinear effects of process parameter amplification, such as increased precursor consumption, changes in reaction kinetics, etc., which may affect the yield and film consistency. Summary of the invention

[0007] In order to solve the problem that the atomic layer deposition system in the prior art cannot meet the deposition requirements of the inner and outer surfaces of large-sized complex and special-shaped parts and the deposition quality is poor, the purpose of the present invention is to provide an anti-coking film layer for complex and special-shaped parts and a preparation method and a preparation system. The anti-coking film layer prepared by this method can inhibit the surface passivation of complex and special-shaped parts in the engine combustion chamber and provide high-temperature anti-coking protection.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for preparing an anti-coking film layer for a complex special-shaped component comprises the following steps:

[0010] 1) The complex special-shaped component is placed in the reaction chamber of the atomic layer deposition system, a titanium source precursor is injected into the reaction chamber, and then an inert gas is introduced to flush the reaction precursor and by-products; an oxygen source precursor is then injected into the reaction chamber; and finally an inert carrier gas is introduced to flush;

[0011] 2) Repeat step 1) until the desired thickness of the film layer is reached to obtain an anti-coking film layer.

[0012] Further, before performing step 1), perform the following steps:

[0013] The atomic layer deposition system is flushed with an inert carrier gas, and then evacuated and baked.

[0014] Furthermore, the baking temperature is 130-230° C. and the baking time is 30-60 min.

[0015] Furthermore, the deposition temperature is 150-250°C.

[0016] Furthermore, the time for injecting the titanium source precursor into the reaction chamber is 1 to 2 seconds, and the time for passing the inert gas to flush the reaction precursor and by-products is 15 to 45 seconds; the time for injecting the oxygen source precursor into the reaction chamber is 0.1 to 0.3 seconds; the time for passing the inert carrier gas to flush is 15 to 35 seconds; and the inert gas flow rate is 100-200 sccm.

[0017] Furthermore, the titanium source precursor is titanium isopropoxide.

[0018] Furthermore, the oxygen source precursor is hydrogen peroxide, and the inert gas is nitrogen.

[0019] Furthermore, the thickness of the film layer is 100 to 250 nm.

[0020] An anti-coking film layer for complex special-shaped parts, wherein the anti-coking film layer is a low-stress film layer with an anatase structure and preferential orientation along the (101) crystal plane, and the residual stress is -30MPa to -100MPa.

[0021] A system for preparing anti-coking films for complex and special-shaped parts, a gas supply system and flow valve, a piping system, an oxygen source precursor, a titanium source precursor, a spiral divergent spoiler, a reaction chamber, a combustion chamber component and a mechanical vacuum pump;

[0022] The gas supply system is connected to the pipeline system through a flow valve, the oxygen source precursor and the titanium source precursor are connected to the pipeline system, the pipeline system is connected to the inlet of the reaction chamber, a spiral divergent spoiler is arranged at the inlet of the reaction chamber, the combustion chamber components are placed in the reaction chamber, and the mechanical vacuum pump is connected to the outlet of the reaction chamber;

[0023] An independent temperature-controlled heating and insulation system is provided outside the reaction chamber;

[0024] The size of the reaction chamber is Φ30×40cm.

[0025] The beneficial effects of the present invention compared with the prior art are as follows:

[0026] In the present invention, a titanium source precursor and an oxygen source precursor are deposited on the surface of complex special-shaped parts through an atomic layer deposition system. The prepared anti-coking film layer can effectively reduce the roughness of the substrate surface and reduce the adhesion of coking products on the substrate surface. At the same time, the compactness of the anti-coking film layer can effectively prevent carbon from penetrating into the metal substrate, thereby achieving the effect of inhibiting coking on the working surface of the combustion chamber parts and improving their working reliability. The high-thickness (100-250nm) anti-coking film layer deposited by the present invention weakens the influence of the substrate on the stress of the film layer. The greater the thickness of the film layer, the less influence the substrate has on the growth mode of the deposited particles, and the better the crystallization of the film layer, which is manifested as the deposition particles starting to crystallize when their own energy is sufficient, and the growth stress gradually increases, which is manifested as compressive stress. The present invention uniformly deposits anti-coking film layers on the surfaces of parts of different metal types, such as aluminum-based materials of pistons, iron-based materials of injectors, etc., wherein the aluminum alloy parts pistons are easily deformed at high temperatures and the fire surface and piston rings have complex special-shaped structures that are not conducive to the preparation of the film layer, and the low-temperature deposition characteristics and good winding plating properties of atomic layer deposition can well solve this problem. And through roughening, the passivation layer is broken, the surface area of ​​the metal substrate is increased, the film layer can be better adhered, and the interlayer bonding force between the film layer and the substrate is enhanced.

[0027] The anti-coking film layer of the present invention presents a crystalline anatase structure and preferentially grows along the (101) direction. The crystalline film layer presents a dense structure and can better achieve the purpose of anti-coking compared with the traditional amorphous structure film layer.

[0028] Furthermore, the present invention has conducted in-depth experimental research on key process parameters in the atomic layer deposition process at the large-scale component level, including the time of injecting titanium source precursor into the reaction chamber, the time of introducing inert gas to flush the reaction precursor and byproducts, the time of injecting oxygen source precursor into the reaction chamber, the time of introducing inert carrier gas to flush, and the deposition temperature. These process parameter amplification nonlinear effect optimization measures not only improve the uniformity and density of the surface film layer of large-area, high-complexity components, especially eliminate the localization effect in the deposition process, and the excellent film quality ultimately enhances the reliability and service life of the combustion chamber components under extreme working conditions.

[0029] The present invention is that, firstly, by optimizing the gas flow guide design, a spiral divergent spoiler is set at the chamber door of the reaction chamber, so that the precursor gas and nitrogen purge are evenly distributed on the sample surface after the chamber size is increased; secondly, an independent temperature-controlled heating and insulation system is added around the entire reaction chamber, and the temperature distribution in the chamber is monitored in real time by a thermal resistor to improve the deposition quality of the film layer, solving the heating uniformity and deposition uniformity problems when the atomic layer deposition system is expanded from a small chamber to a large chamber. In addition, the size of the atomic layer deposition system reaction chamber used in the present invention is set to Ф30×40cm, so that the precursor is evenly distributed in the reaction chamber through the flow guide device and flows through the surface of the component to be plated. At the same time, the temperature control system used in the atomic layer deposition system designed by the present invention can achieve accurate control of ±2°C. The present invention can meet the requirements of uniform coating of the inner and outer surfaces of large-sized complex and special-shaped components, and form an effective film layer with high purity and good uniformity. At the same time, the limitation of atomic layer deposition on sample size requirements is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a simplified schematic diagram of a large-scale reaction chamber atomic layer deposition system;

[0031] Figure 2 Schematic diagram of typical combustion chamber components; (a) is the external schematic diagram of the injector, (b) is the internal schematic diagram of the injector; (c) is the cylinder head,

[0032] Figure 3 These are injector samples with 2000-cycles-TiO2 and 3000-cycles-TiO2 film layers; wherein (a) is an injector sample with 2000-cycles-TiO2 film layer, and (b) is an injector sample with 3000-cycles-TiO2 film layer;

[0033] Figure 4 This is a scanned image of the cross-sectional morphology of the 3000-cycles-TiO2 film;

[0034] Figure 5 XRD spectra of anti-coking films with different thicknesses;

[0035] Figure 6 is the stress measurement curve of TiO2 film;

[0036] Figure 7 Figure 1 is a graph showing the anti-coking performance of substrates and film layers of different materials; (a) is the initial state of the iron-based material, (b) is the iron-based material after high-temperature testing; (c) is the initial state of the iron-based material surface coating, (d) is the iron-based material surface coating after high-temperature testing; (e) is the initial state of the aluminum-based material, (f) is the aluminum-based material after high-temperature testing; (g) is the initial state of the aluminum-based material surface coating, (h) is the aluminum-based material surface coating after high-temperature testing;

[0037] Among them, 1 is a gas supply system, 2 is a flow valve, 3 is a pipeline system, 4 is an oxygen source precursor, 5 is a titanium source precursor, 6 is a spiral divergent spoiler, 7 is a reaction chamber, 8 is a combustion chamber component, and 9 is a mechanical vacuum pump;

[0038] 2-1 is the pressure regulating screw, 2-2 is the injector body, 2-3 is the needle valve body, 2-4 is the pressure regulating spring, 2-5 is the push rod, 2-6 is the needle valve; 2-7 is the intake valve hole, 2-8 is the exhaust valve hole, 2-9 is the spark plug hole, and 2-10 is the cooling water channel. DETAILED DESCRIPTION

[0039] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly and comprehensively understood.

[0040] The complex special-shaped parts in the present invention are the components of the combustion chamber with complex geometric structures and made of different materials.

[0041] (I) Preparation method of anti-coking film layer for complex special-shaped parts

[0042] The present invention provides a method for preparing an anti-coking film layer for a complex special-shaped component, which is carried out by using an atomic layer deposition system. Figure 1 Schematic diagram of a large-size (Ф30×40cm) reaction chamber atomic layer deposition system used in an embodiment of the present invention, wherein the atomic layer deposition system includes a gas supply system 1 (high-purity nitrogen) and a flow valve 2, a piping system 3, an oxygen source precursor 4, a titanium source precursor 5, a spiral divergent spoiler 6, a reaction chamber 7 (a heating and insulation system with independent temperature control is provided outside the chamber), a combustion chamber component 8 and a mechanical vacuum pump 9.

[0043] Among them, the gas supply system 1 is connected to the pipeline system 3 through the flow valve 2, the oxygen source precursor 4 and the titanium source precursor 5 are connected to the pipeline system 3, the pipeline system 3 is connected to the entrance of the reaction chamber 7, a spiral divergent spoiler 6 is arranged at the entrance of the reaction chamber 7, the combustion chamber component 8 is placed in the reaction chamber 7, and the mechanical vacuum pump 9 is connected to the outlet of the reaction chamber 7.

[0044] The bottle containing the oxygen source precursor 4 and the bottle containing the titanium source precursor 5 are placed in tubular flexible heating jackets respectively.

[0045] The size of the reaction chamber is Ф30×40cm. The large-sized reaction chamber can be used to prepare surface film layers of workpieces of different sizes with complex structures such as holes and pipes.

[0046] The present invention optimizes the design of the gas guide device and adds a spiral divergent spoiler 6 at the chamber door, so that the precursor gas and nitrogen purge are evenly distributed on the sample surface after the chamber size is increased; secondly, an independent temperature-controlled heating and insulation system is added around the entire chamber, and the temperature distribution in the chamber is monitored in real time by a thermal resistor to improve the deposition quality of the film layer. Therefore, the present invention can inhibit the surface passivation of complex and special-shaped parts of the engine combustion chamber and provide high-temperature anti-coking protection.

[0047] Figure 2 For typical complex components of applicable combustion chambers, see Figure 2 In (a) and (b), the fuel injector includes a fuel injector body 2-2, a pressure regulating spring 2-4 is arranged on the upper part of the fuel injector body 2-2, a pressure regulating screw 2-1 is arranged on the top of the fuel injector body 2-2, a push rod 2-5 is arranged on the lower part of the fuel injector body 2-2, a needle valve body 2-3 is arranged on the bottom end of the fuel injector body 2-2, and a needle valve 6 is arranged on the bottom end of the needle valve body 2-3.

[0048] See also Figure 2 In (c), the cylinder includes a cylinder head. In the combustion chamber, the cylinder head is provided with an intake valve hole 2-1, an exhaust valve hole 2-2, a spark plug hole 2-3 and a cooling water channel 2-4. An intake valve is installed at the intake valve hole 2-1 and an exhaust valve is installed at the exhaust valve hole 2-2. The intake valve and the exhaust valve are responsible for controlling the intake and exhaust respectively. The intake valve opens during the intake stroke to introduce fresh air into the cylinder; the exhaust valve opens during the exhaust stroke to discharge the exhaust gas after combustion out of the cylinder. They are connected to the camshaft through valve springs and valve tappets and other components, and their opening and closing are controlled by the camshaft. A fuel injector is also installed in the center of the cylinder head. When the compression stroke approaches the top dead center, the fuel injector sprays high-pressure diesel into the combustion chamber, mixes with high-temperature and high-pressure air, forms a combustible mixture, and is then ignited to produce combustion, thereby completing the combustion process, converting the chemical energy of diesel into mechanical energy to drive the engine to operate.

[0049] The present invention firstly optimizes the gas flow guide design and adds a spiral divergent spoiler 6 at the chamber door of the reaction chamber, so that the precursor gas and nitrogen purge are evenly distributed on the sample surface after the chamber size is increased; secondly, an independent temperature-controlled heating and insulation system is added around the entire chamber, and the temperature distribution in the reaction chamber is monitored in real time by a thermal resistor to improve the deposition quality of the film layer. Therefore, the present invention can inhibit the surface passivation of complex and special-shaped parts of the engine combustion chamber and provide high-temperature anti-coking protection.

[0050] A method for preparing an anti-coking film layer for a complex special-shaped component of the present invention specifically comprises the following steps:

[0051] 1) Clean and dry the combustion chamber components (including injectors, cylinder heads, etc.) to make the surface of the components clean; remove dust and clean the reaction chamber of the atomic layer deposition system; suspend the combustion chamber components in the reaction chamber of the atomic layer deposition system so that the airflow can fully flow through the working inner and outer surfaces of the components, and close the chamber door to ensure the sealing of the chamber.

[0052] 2) Introduce inert carrier gas (high-purity nitrogen) into the atomic layer deposition system to repeatedly flush the pipeline and reaction chamber, then evacuate the reaction chamber to make the pressure below 50mtorr, and heat and bake for 30-60 minutes to remove moisture and other volatile impurities in the reaction chamber, while achieving thermal equilibrium inside the chamber and reducing the temperature gradient inside the chamber, thereby ensuring the uniformity and quality of the film. After baking, heat to the deposition temperature.

[0053] Preferably, in step 2), due to the cooperation between different parts of the combustion chamber, too high a temperature will cause deformation of the parts and affect the cooperation, while too low a temperature will lead to low deposition efficiency, so the baking temperature is selected to be 130-230°C and the deposition temperature is 150-250°C. A tubular flexible heating jacket is used to control the evaporation temperature of the precursor at 70-90°C.

[0054] 3) injecting a titanium source precursor into the reaction chamber for a time period of t1; introducing an inert gas to flush out excess titanium source precursor and by-products for a time period of t2; injecting an oxygen source precursor into the reaction chamber for a time period of t3; and introducing an inert carrier gas to flush out excess oxygen source precursor and by-products for a time period of t4;

[0055] Preferably, in step 3), titanium isopropoxide is used as the titanium source precursor, H2O2 (mass fraction is 30%) is used as the oxygen source precursor, and high-purity nitrogen (N2 with a purity of 99.999%) is used as the inert purge gas.

[0056] Preferably, in step 3), the injection time t1 of the titanium source precursor titanium isopropoxide is 1 to 2 seconds, the high-purity nitrogen purge time t2 is 15 to 45 seconds, the injection time t3 of the oxygen source precursor H2O2 is 0.1 to 0.3 seconds, and the high-purity nitrogen purge time t4 is 15 to 35 seconds. The high-purity nitrogen flow rate is 100-200 sccm.

[0057] 4) Repeat step 3) until the desired thickness of the TiO2 anti-coking layer, i.e., the anti-coking film layer, is reached.

[0058] Preferably, in step 4), the cycle period is 2000 to 3000 times, and the thickness of the anti-coking film layer is 100 to 250 nm.

[0059] The anti-coking film layer prepared by the invention is a low-stress film layer with an anatase structure and a preferred orientation along the (101) crystal plane, and the residual stress is -30MPa to -100MPa.

[0060] The anti-coking film layer prepared by the present invention has high-temperature anti-coking performance on the working surface of complex and special-shaped parts in the combustion chamber. After a high-temperature test of 500-800°C, the coking performance of the surface film layer of the aluminum-based material is excellent, and the anti-coking area is 98%.

[0061] The anatase crystalline TiO2 anti-coking film layer prepared by the present invention can prevent the penetration of carbon elements into substrates of different materials, reduce the catalytic effect of active sites of the substrate, significantly extend the service life of complex components of the combustion chamber, and improve their performance in extreme environments.

[0062] The following are specific embodiments.

[0063] Example 1

[0064] This embodiment provides a method for preparing an anti-coking film layer on the working surface of a fuel injector in a combustion chamber by using atomic layer deposition (ALD), and the method specifically comprises the following steps:

[0065] 1) Immerse the injector in a solution with a volume ratio of detergent: deionized water = 1:30, then put it into an industrial ultrasonic machine and heat it to 50°C. Clean it for 10 minutes. After taking it out, quickly rinse and dehydrate it with alcohol. This step can effectively remove oil stains and impurities on the inner and outer surfaces of the injector and prevent subsequent rust. Then use alcohol to clean it for 10 minutes to remove residual detergent and impurities.

[0066] 2) Use a dust removal device to remove dust from the reaction chamber, and scrub the inner wall of the reaction chamber with anhydrous ethanol. After cleaning, suspend the injector in a 30×40cm reaction chamber, with the top injection hole of the injector facing the air intake direction and the horizontal distance from the chamber door being 17cm.

[0067] 3) Preset ALD equipment process parameters;

[0068] 4) Evacuate the reaction chamber to make the pressure in the reaction chamber lower than 50 mtorr.

[0069] 5) Use high-purity nitrogen to flush the pipeline multiple times by controlling the pipeline valve switch to prevent the CVD reactants in the pipeline from clogging the pipeline.

[0070] 6) Turn on the reaction chamber heating device, heat to 130°C and keep it warm for 30-60 minutes, then raise the temperature to the deposition temperature of 150°C and maintain it. Use a tubular flexible heating jacket to control the temperature of the precursor titanium isopropoxide to 70-90°C.

[0071] 7) The precursor titanium isopropoxide is injected into the reaction chamber for 1 s. The time t1 is 1s. The excess reaction precursor and by-products are cleaned by passing high-purity nitrogen gas with a flow rate of 200 sccm for 18s. The oxygen source precursor H2O2 is injected for 0.1s at t3 and the excess oxygen source precursor and by-products are cleaned by passing high-purity nitrogen gas with a flow rate of 200 sccm for 17s at t4.

[0072] 8) Repeat step 7) for 2000 cycles to form an anti-coking film layer for complex special-shaped parts.

[0073] It has been proven that the anti-coking film effect of complex and special-shaped parts is as follows: Figure 3 As shown in (a), a thick yellow TiO2 anti-coking passivation layer can be formed.

[0074] Example 2

[0075] The other conditions are the same as those of Experimental Example 1, except that step 7) is repeated for 3000 cycles to form an anti-coking film layer for complex special-shaped parts.

[0076] The effect of anti-coking film on complex and special-shaped parts is as follows Figure 3 As shown in (b), the film is blue. The film thickness is further analyzed by SEM, and the effect is as follows Figure 4 As shown, a TiO2 anti-coking passivation layer with a thickness of 210nm can be formed. Figure 5 It can be seen that the film layer is an anatase structure that preferentially grows along (101). The residual stress test is performed on it, and the test curve obtained is as follows: Figure 6 As shown, the residual stress value is -36.4MPa.

[0077] Example 3

[0078] Step 1) to step 5) are the same as in Example 1;

[0079] 6) Turn on the heating device of the reaction chamber, heat to 230°C and keep it warm for 30 minutes, then raise the temperature to the deposition temperature of 250°C and maintain it. Use a tubular flexible heating jacket to control the temperature of titanium isopropoxide to 70-90°C.

[0080] 7) The precursor titanium isopropoxide is injected into the reaction chamber for 1 s, and the time t1 is 1s; the high-purity nitrogen gas with a flow rate of 200 sccm is introduced to clean the excess reaction precursor and by-products for 15 s; the oxygen source precursor H2O2 is injected for 0.1s, and the high-purity nitrogen gas with a flow rate of 200 sccm is introduced to clean the excess oxygen source precursor and by-products for 35s.

[0081] 8) Repeat step 7) for 2000 cycles to form an anti-coking film layer for complex special-shaped parts.

[0082] Example 4

[0083] Step 1) to step 5) are the same as in Example 1;

[0084] 6) Turn on the heating device of the reaction chamber, heat to 130°C and keep it warm for 60 minutes, then raise the temperature to the deposition temperature of 200°C and maintain it. Use a tubular flexible heating jacket to control the temperature of titanium isopropoxide to 70-90°C.

[0085] 7) The precursor titanium isopropoxide is injected into the reaction chamber for 1 second. The excess reaction precursor and by-products are cleaned with high-purity nitrogen gas at a flow rate of 200 sccm for 45 seconds. The oxygen source precursor H2O2 is injected for 0.2 seconds at t3 and the excess oxygen source precursor and by-products are cleaned with high-purity nitrogen gas at a flow rate of 200 sccm for 25 seconds at t4.

[0086] 8) Repeat step 7) for 2000 cycles to form an anti-coking film layer for complex special-shaped parts.

[0087] Example 5

[0088] Step 1) to step 5) are the same as in Example 1;

[0089] 6) Turn on the heating device of the reaction chamber, heat to 180°C and keep it warm for 40 minutes, then raise the temperature to the deposition temperature of 180°C and maintain it. Use a tubular flexible heating jacket to control the temperature of titanium isopropoxide to 70-90°C.

[0090] 7) The precursor titanium isopropoxide is injected into the reaction chamber for 1 s. The time t1 is 1s. The excess reaction precursor and by-products are cleaned by passing high-purity nitrogen gas with a flow rate of 200 sccm for 30s. The oxygen source precursor H2O2 is injected for 0.3s at t3 and the excess oxygen source precursor and by-products are cleaned by passing high-purity nitrogen gas with a flow rate of 200 sccm for 15s at t4.

[0091] 8) Repeat step 7) for 2000 cycles to form an anti-coking film layer for complex special-shaped parts.

[0092] (II) Test on the anti-coking performance of the film layer

[0093] The anti-coking performance of the experimental piece (iron-based material or aluminum-based material) coated with the TiO2 film in Example 2 was tested at 500-800°C for 30 minutes by using the thermal shock of a No. 0 diesel flame to simulate the actual service conditions. At the same time, the carbon adhesion on the surface of the sample was processed using image processing software, such as Figure 7 As shown in (a)-(b), the carbon adhesion area on the surface of the iron-based material is 9%. After the TiO2 film is coated, Figure 7 As shown in (c)-(d), there is no obvious carbon deposition on the film surface, and the anti-carbon deposition area is 95%. Figure 7 As shown in (e)-(f), the carbon attachment area on the surface of the aluminum-based material is 48%; Figure 7 As shown in (g)-(h), after the TiO2 film is coated, no obvious carbon deposition is generated on the surface, and the anti-carbon deposition area is 98%. The results show that the TiO2 anti-coking layer prepared by the present invention has excellent anti-coking performance.

[0094] The above description is only for the best embodiment of the present invention, but it should not be understood as limiting the claims. The present invention is not limited to the above embodiments, and its specific structure is allowed to be changed. However, all changes made within the protection scope of the independent claims of the present invention are within the protection scope of the present invention.

[0095] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

Claims

1. A method for preparing an anti-coking film layer for complex special-shaped parts, characterized in that: The following steps are involved: 1) The complex special-shaped component is placed in the reaction chamber of the atomic layer deposition system, a titanium source precursor is injected into the reaction chamber, and then an inert gas is introduced to flush the reaction precursor and by-products; an oxygen source precursor is then injected into the reaction chamber; and finally an inert carrier gas is introduced to flush; 2) Repeat step 1) until the desired thickness of the film layer is reached to obtain an anti-coking film layer.

2. The method for preparing an anti-coking film layer for complex special-shaped parts according to claim 1, characterized in that: Before proceeding to step 1), perform the following steps: The atomic layer deposition system is flushed with an inert carrier gas, and then evacuated and baked.

3. The method for preparing the anti-coking film layer of complex special-shaped parts according to claim 2, characterized in that: The baking temperature is 130-230°C and the baking time is 30-60 minutes.

4. The method for preparing an anti-coking film layer for complex special-shaped parts according to claim 1, characterized in that: The deposition temperature is 150-250°C.

5. The method for preparing an anti-coking film layer for complex special-shaped parts according to claim 1, characterized in that: The time for injecting the titanium source precursor into the reaction chamber is 1 to 2 seconds, and the time for flushing the reaction precursor and by-products with inert gas is 15 to 45 seconds; the time for injecting the oxygen source precursor into the reaction chamber is 0.1 to 0.3 seconds; The flushing time of the inert carrier gas is 15 to 35 seconds; the inert gas flow rate is 100 to 200 sccm.

6. The method for preparing an anti-coking film layer for complex special-shaped parts according to claim 1, characterized in that: The titanium source precursor is titanium isopropoxide.

7. The method for preparing an anti-coking film layer for complex special-shaped parts according to claim 1, characterized in that: The oxygen source precursor is hydrogen peroxide, and the inert gas is nitrogen.

8. The method for preparing an anti-coking film layer for complex special-shaped parts according to claim 1, characterized in that: The thickness of the film layer is 100 to 250 nm.

9. An anti-coking film layer for complex special-shaped parts prepared according to the method according to any one of claims 1 to 8, characterized in that: The anti-coking film layer is a low-stress film layer with an anatase structure and a preferred orientation along the (101) crystal plane, and the residual stress is -30MPa to -100MPa.

10. A system for preparing an anti-coking film layer for complex special-shaped parts according to the method of any one of claims 1 to 8, characterized in that: A gas supply system (1) and a flow valve (2), a pipeline system (3), an oxygen source precursor (4), a titanium source precursor (5), a spiral divergent spoiler (6), a reaction chamber (7), a combustion chamber component (8) and a mechanical vacuum pump (9); The gas supply system (1) is connected to the pipeline system (3) via a flow valve (2); the oxygen source precursor (4) and the titanium source precursor (5) are connected to the pipeline system (3); the pipeline system (3) is connected to the inlet of the reaction chamber (7); a spiral divergent spoiler (6) is provided at the inlet of the reaction chamber (7); a combustion chamber component (8) is placed in the reaction chamber (7); and a mechanical vacuum pump (9) is connected to the outlet of the reaction chamber (7); The outside of the reaction chamber (7) is provided with an independent temperature-controlled heating and insulation system; The size of the reaction chamber (7) is Φ30×40 cm.

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