Antioxidant Nano-Magnetic Alloy @SiO2 / Glass Composite Absorbing Coating for Thermal Spraying and Its Preparation and Application

Abstract

The present invention relates to an antioxidant nano-magnetic alloy@SiO2 / glass composite wave-absorbing coating for thermal spraying, its preparation and application. By using glass powder materials with different melting ranges to regulate the power of thermal spraying, the antioxidant property of nano-magnetic alloy powder is improved; by using different ball-to-material ratios, ball milling speeds and times to regulate the particle size of glass powder materials, the fluidity of the slurry and the mechanical properties of the coating are improved; by using one-step chemical coating to regulate the wetting condition between nano-magnetic alloy and glass powder materials, the antioxidant property and the mechanical properties of the coating are further improved, etc. The process of the present invention is simple in operation and easy for mass production, solving the problems that it is difficult to increase the volume content of magnetic wave-absorbing agents because they are prone to form conductive networks due to flattening, and that nano-magnetic wave-absorbing agents are easily oxidized during the thermal spraying process, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite absorbing coating preparation, and relates to an antioxidant nano-magnetic alloy@SiO2 / glass composite absorbing coating for thermal spraying, and its preparation and application. Background Art

[0002] Stealth technology is an important technical means to achieve information acquisition and seize the initiative in future information-based wars. It is an important foundation for both sides of the offensive and defensive confrontation to gain strategic, campaign, tactical and technical advantages, and is also a remarkable technical feature of a new generation of weapons and equipment. Radar absorbing material technology is an important technology for stealth. According to functions, it is divided into coated absorbing materials, patch type, structural type and other absorbing materials. Coated absorbing materials have the characteristics of not being restricted by the structure of components and being easy to construct, and were the first to be widely studied. Magnetic loss absorbing materials are the earliest and most widely used absorbing materials. Compared with resistive and dielectric absorbers, magnetic absorbing coatings have greater advantages in reducing the thickness of materials.

[0003] Thermal spraying technology is one of the most effective surface modification technologies in the field of surface engineering. In thermal spraying technology with plasma arc, arc and combustion flame as heat sources, the powder is heated to a molten state and then impacts and deposits on the substrate at high speed. In this process, phase change, chemical reaction and other phenomena inevitably occur, and the flaky morphology is also the main morphology of the magnetic alloy in the coating after thermal spraying, making it extremely easy to form a conductive network in the coating structure and affecting the absorbing performance of the coating. Although low-temperature cold spraying does not heat to the molten state, the plastic deformation caused by its high-speed impact also makes the magnetic alloy mainly in the flaky morphology in the coating structure. The volume concentration of alloy powder in the functional coating directly affects its absorbing ability. Too low a concentration cannot effectively dissipate the electromagnetic waves incident into the coating, and the attenuation effect is poor, while too high a concentration will form a complex conductive network covering the whole in the coating interior and on the surface, making the electromagnetic properties of the coating similar to those of metals. Due to the skin effect in the microwave band, good impedance matching cannot be achieved, and the vast majority of electromagnetic waves are reflected, which also does not meet the characteristics of the absorbing coating. Therefore, selecting an appropriate concentration ratio of cobalt and alumina is the key to preparing the absorbing coating, which is essentially a percolation problem. With the increase of the volume ratio, most magnetic absorbers are more likely to form a conductive network due to the inevitable flakiness caused by the thermal spraying mechanism, so it is difficult to prepare a magnetic composite absorbing coating with a high filling ratio.

[0004] Chinese Patent Application CN102758164A discloses a thermal spraying powder material for a radar absorbing coating, a thermal spraying radar absorbing coating and a preparation method thereof. The radar absorbing coating includes an absorbent and an inorganic binder for bonding and dispersing the absorbent, and the inorganic binder is selected from glass, glaze or enamel materials. Moreover, the forming process of the coating is a thermal spraying process. However, the absorbent used in this technical solution has a relatively large particle size. Although it is not easily oxidized, it is difficult to increase the mass fraction, and the large-sized absorbent is not melted, which affects the coating bonding strength. Summary of the Invention

[0005] An object of the present invention is to provide an antioxidant nano-magnetic alloy@SiO2 / glass composite absorbing coating for thermal spraying, and its preparation and application.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] One of the technical solutions of the present invention provides a preparation method of an antioxidant nano-magnetic alloy@SiO2 / glass composite absorbing coating for thermal spraying, including the following steps:

[0008] (1) Take nano-magnetic alloy powder and disperse it in a mixed solution of ethanol and water, add ammonia water and mix, then add tetraethyl orthosilicate, react, wash and dry to obtain nano-magnetic alloy@SiO2 composite powder;

[0009] (2) Take glass powder and add it to a ball milling tank, add zirconia balls and perform ball milling treatment;

[0010] (3) Then mix the ball-milled glass powder obtained in step (2) with the obtained nano-magnetic alloy@SiO2 composite powder and add them to a ball milling tank, then add PVA solution and ammonium citrate, and add zirconia balls, and perform rolling stirring to obtain a slurry for spray granulation, dry and sieve to obtain nano-magnetic alloy@SiO2 / glass composite powder;

[0011] (4) Take the substrate, clean and sandblast it, and then use the atmospheric plasma spraying process to spray the bonding layer and the functional layer successively, wherein the functional layer uses the nano-magnetic alloy@SiO2 / glass composite powder obtained in step (3) as the coating raw material, and that's it.

[0012] In step (1), the volume ratio of ethanol to water is 3-6:1.

[0013] In step (1), the addition amount of ammonia water satisfies that the pH of the solution system is 10-11.

[0014] In step (1), the addition amount of tetraethyl orthosilicate satisfies that its molar concentration in the solution system is 0.5 - 1.5%. The volume ratio of alcohol to water, the addition amount of ammonia water, and the concentration of TEOS defined in the present invention are all for regulating the hydrolysis rate of TEOS, which is beneficial to the heterogeneous nucleation of SiO2 on the surface of the nano magnetic alloy powder.

[0015] In step (1), the nano magnetic alloy powder is a magnetic alloy powder with a Curie temperature > 500 °C. Specifically, the nano magnetic alloy powder can be Nano-FeCoNi.

[0016] In step (1), the reaction temperature is room temperature, and the reaction time is 6 - 10 h.

[0017] In step (2), the glass powder used is a low melting point glass powder with a melting range < 500 °C (the heating range is 390 °C - 1100 °C). Specifically, CBS series glass-ceramic powder can be used.

[0018] In step (2), the ball-to-powder ratio during ball milling is 4 - 10:1, the ball milling speed is 320 - 500 r / min, and the time is 2 - 10 h.

[0019] In step (3), in the obtained slurry, the solid content is 30 - 50 wt%, the proportion of the nano magnetic alloy powder is 20 - 35 vol%, the mass of PVA added is 1 - 5% of the sum of the masses of the nano magnetic alloy@SiO2 composite powder and the glass powder, and the mass of ammonium citrate added is 0.5 - 1% of the sum of the masses of the nano magnetic alloy@SiO2 composite powder and the glass powder. PVA is used as a binder and a dispersant here, and ammonium citrate is used as a dispersant here.

[0020] In step (3), the addition amount of zirconia balls satisfies: the ball-to-powder ratio is 3 - 5:1.

[0021] In step (3), during spray granulation, the inlet and outlet temperatures of the spray granulator are controlled at 250 °C and 118 °C respectively, the feeding speed is 19.18 mL / min, and the atomizer frequency is 25 Hz.

[0022] In step (3), the drying temperature is 80 - 90 °C.

[0023] In step (3), the sieving process is specifically: passing through 32 μm and 100 μm sieves, the amplitude of the vibrating sieve is 80 - 95%, and the vibrating time is 5 - 10 min. Passing through 32 μm and 100 μm respectively is to make the powder have better fluidity, which is beneficial to the coating performance of thermal spraying.

[0024] In step (4), the substrate is 304 stainless steel.

[0025] In step (4), the bonding layer is Ni@Al.

[0026] In step (4), the distance between the spray gun nozzle and the substrate is 10 - 15 cm, the powder feeding rate is 10 - 15 g / min, the spraying power is 30 - 55 KW, and the rates of argon, nitrogen, and hydrogen are 4000 - 500 L / min, 2000 - 2500 L / min, and 1500 - 2000 L / min respectively.

[0027] The second technical solution of the present invention provides an antioxidant nano - magnetic alloy@SiO2 / glass composite wave - absorbing coating for thermal spraying, which is prepared by the preparation method as described above.

[0028] The third technical solution of the present invention provides an application of an antioxidant nano - magnetic alloy@SiO2 / glass composite wave - absorbing coating for thermal spraying in the preparation of wave - absorbing materials.

[0029] Due to surface effect, small - size effect, quantum - size effect, and macroscopic quantum tunneling effect, various electromagnetic or physical properties of nanoparticles change. For example, unique soft - magnetic material properties such as high saturation magnetization intensity, low coercivity, and high magnetic permeability are possessed by FeCoNi nano - alloys, etc. Thus, nano - magnetic alloy powders are subjected to less impact stress during the spraying process, and the deposition efficiency and the denseness of the structure will also be significantly improved. However, nano - magnetic alloy powders are more likely to be fully melted during the spraying process. In view of the "sand - stone effect", the present invention selects a low - temperature binder with a melting temperature lower than that of the nano - magnetic alloy powder, so that it is preferentially and fully melted during the melting process and coats the surface of the nano - magnetic alloy powder. On the one hand, the low - temperature binder plays a role in heat insulation and antioxidation, hindering the full melting and oxidation of the nano - magnetic powder. On the other hand, it can reduce the impact stress when the nano - magnetic alloy powder impacts the substrate, and can avoid the tendency of the nano - magnetic alloy powder to be flaky, thereby increasing the filling ratio of the nano - magnetic powder.

[0030] Meanwhile, the glass powder materials such as CaO - B2O3 - SiO2 (CBS) system microcrystalline glass used in the present invention have the characteristics of low dielectric constant, low dielectric loss, low thermal expansion coefficient (similar to SiO2), and good matching with metals. In addition, the particle size and particle size distribution of the glass powder have important effects on the internal structure and properties of the coating. When the powder particle size is small, the specific surface area is large, the sintering activity is high, the crystallization temperature is low, the grains are finer, and the coating structure is denser; when the powder particle size distribution is narrow and the particle size is uniform, it can avoid defects in the coating structure caused by over - large local grains, which affects the mechanical properties. This is mainly because the finer the powder, the larger the surface area, the increased reaction activity, the lower the glass softening point, the smaller the viscosity of the glass melted into the liquid phase, and thus the better the fluidity. Under the action of the driving force of liquid - phase sintering, the particles slide and rearrange to achieve more effective close packing.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] (1) By using glass powder materials with different melting ranges to regulate the power of thermal spraying, the oxidation resistance of the nano-magnetic alloy powder is improved;

[0033] (2) By using different ball-to-material ratios, ball milling speeds, and times to regulate the particle size of the glass powder material, the fluidity of the slurry and the mechanical properties of the coating are improved;

[0034] (3) By using one-step chemical coating to regulate the wetting situation between the nano-magnetic alloy and the glass powder material, the oxidation resistance and the mechanical properties of the coating are further improved;

[0035] (4) By adding nano-magnetic alloy powder to regulate the electromagnetic parameters of the composite powder, as well as the slurry concentration and additive ratio during the preparation process of the composite powder, the performance of the composite wave-absorbing coating is systematically regulated. The process operation is simple and it is easy to carry out mass production;

[0036] (5) It solves the problems that it is difficult to increase the volume content of the magnetic wave-absorbing agent in the composite wave-absorbing coating because the magnetic wave-absorbing agent is prone to form a conductive network due to flattening, and the nano-magnetic wave-absorbing agent is easily oxidized during the thermal spraying process, which has very important guiding significance for the preparation of high-temperature magnetic composite wave-absorbing coatings. Description of the Drawings

[0037] Figure 1 SEM image of Nano-FeCoNi powder in Example 1;

[0038] Figure 2 SEM image of the powder obtained in Step 1 of Example 1;

[0039] Figure 3 SEM image of the powder obtained in Step 3 of Example 1;

[0040] Figure 4 SEM image of the coating obtained in Step 5 of Example 1;

[0041] Figure 5 SEM image of the coating obtained in Step 5 of Example 2;

[0042] Figure 6 SEM image of the coating obtained in Step 4 of Example 3;

[0043] Figure 7 SEM image of the granulated powder obtained in Comparative Example 4;

[0044] Figure 8 SEM image of the composite coating obtained in Comparative Example 1;

[0045] Figure 9XRD patterns of Example 1, Example 3 and Comparative Example 1;

[0046] Figure 10 Reflectivity diagram of the coating obtained in Example 1. Detailed implementation mode

[0047] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0048] In the following embodiments, the substrate used is 304 stainless steel. The sprayed bonding layer Ni@Al is purchased from Nangong Yueze Welding Materials Co., Ltd., and the product model is Ni60WC. The FeCoNi powder used is purchased from Shanghai Changbei Nanomaterials Technology Co., Ltd., the CBS powder is purchased from Hebei Fangji New Materials Technology Co., Ltd., and the FeSiAl powder is purchased from Changsha Tianjiu Metal Materials Co., Ltd.

[0049] For the rest of the raw materials or processing technologies without special instructions, it means that they are all conventional commercially available raw materials or conventional processing technologies in this field.

[0050] Example 1

[0051] Step 1: Preparation of SiO2 shell layer

[0052] 400 g of Nano-FeCoNi was evenly dispersed in a mixed solution of 2.4 L of ethanol and 0.6 L of water under mechanical stirring at 400 r / min. Subsequently, 120 mL of ammonia water (concentration: 13.33 mol / L) was added and mixed evenly. Finally, 100 mL of TEOS was added to the above mixed solution. After reacting at room temperature for 8 h, it was washed repeatedly with anhydrous ethanol and collected by magnetic separation. After repeating the collection 3 times, it was placed in a drying oven at 60 °C to dry for later use, and the Nano-FeCoNi@SiO2 composite powder could be obtained.

[0053] Step 2: Powder property regulation

[0054] 1 kg of CBS powder was put into a stainless steel ball milling tank, and then 4 kg of 1.0 - 1.2 mm zirconia balls were added. It was ball milled for 10 h under the condition of 500 r / min to obtain the ball milled CBS powder for later use.

[0055] Step 3: Preparation of composite powder

[0056] Add the Nano-FeCoNi@SiO2 composite powder obtained in Step 1 to the ball milling tank. On the basis of controlling the content of Nano-FeCoNi to be 30 vol%, add the CBS powder obtained in Step 2. Then add PVA accounting for 2.5% of the total mass of the Nano-FeCoNi@SiO2 composite powder and the CBS powder, and ammonium citrate accounting for 0.8% of the total mass of the Nano-FeCoNi@SiO2 composite powder and the CBS powder. Add zirconia balls with a diameter of 1.0 - 1.2 mm according to a ball-to-material ratio of 4:1, and roll and stir for 10 h to obtain a slurry (control the solid content of the slurry to be about 40 wt%); Inject the obtained slurry into a spray granulator through a peristaltic pump for spray granulation. Control the inlet and outlet temperatures at 250 °C and 118 °C respectively, the feeding speed at 19.18 mL / min, and the atomizer frequency at 25 Hz. Then dry the residual water vapor of the composite powder at 80 - 90 °C and pass it through sieves with mesh sizes of 32 μm and 100 μm, and collect the powder with a particle size of 32 - 100 μm, that is, obtain the Nano-FeCoNi@SiO2 / CBS composite powder;

[0057] Step 4: Measure the particle size and fluidity

[0058] Measure the particle size and fluidity of the composite powder collected in Step 4 through a laser particle size analyzer and a Hall flowmeter respectively. Measure its D50 to be 61.2 μm with the laser particle size analyzer, and the fluidity is 112 s / 50 g;

[0059] Step 5: Atmospheric plasma spraying

[0060] Wash the oil stain on the surface of the substrate with ethanol, acetone, etc., and then perform sandblasting treatment on the substrate. Then fix the sandblasted substrate in a spraying system composed of a 100HE atmospheric plasma spraying device produced by Progressive Surface Company and a mechanical arm with the model IRB 2600 produced by ABB Engineering Company. Measure the powder feeding rate to be 13 g / min, and set the mechanical arm program including the distance from the substrate to be 12 cm, the step distance (mm) 3 * 42, and the number of cycles (non-stop) 6. Then set the spraying power to 35 KW, and the rates of argon, nitrogen, and hydrogen to be 4529.6 L / min, 2264.8 L / min, and 1698.6 L / min respectively. After setting, preheat the substrate, and then spray the bonding layer Ni@Al and the functional layer Nano-FeCoNi@SiO2 / CBS successively, where the thickness of the bonding layer is 100 μm and the thickness of the functional layer is 1 mm.

[0061] Example 2

[0062] Step 1: Preparation of the SiO2 shell layer

[0063] 400 g of Nano-FeCoNi was evenly dispersed in a mixed solution of 2.4 L of ethanol and 0.6 L of water under mechanical stirring at 400 r / min. Subsequently, 120 mL of ammonia water was added and mixed evenly. Finally, 100 mL of TEOS was added to the above mixed solution. After reacting at room temperature for 8 h, it was repeatedly washed with absolute ethanol and then magnetically collected. After repeating the collection 3 times, it was placed in a drying oven at 60 °C for drying and standby, and the Nano-FeCoNi@SiO2 composite powder could be obtained.

[0064] Step 2: Powder property regulation

[0065] 1 kg of CBS powder was put into a stainless steel ball milling tank, and then 4 kg of 1.0 - 1.2 mm zirconia balls were added. Ball milling was carried out at 500 r / min for 10 h to obtain the CBS powder with the corresponding particle size for standby.

[0066] Step 3: Composite powder preparation

[0067] The Nano-FeCoNi@SiO2 composite powder obtained in Step 1 was added to the ball milling tank. On the basis of controlling the content of Nano-FeCoNi to be 20 vol%, a certain amount of the CBS powder obtained in Step 2 was added. Then, 2.5% of PVA based on the sum of the masses of the Nano-FeCoNi@SiO2 composite powder and the CBS powder, and 0.8% of ammonium citrate based on the sum of the masses of the Nano-FeCoNi@SiO2 composite powder and the CBS powder were added. And 1.0 - 1.2 mm zirconia balls were added according to the ball-to-material ratio of 4:1, and rolling stirring was carried out for 10 h to obtain a slurry (controlling the solid content of the slurry to be about 40 wt%); the obtained slurry was injected into a spray granulator through a peristaltic pump for spray granulation. The inlet and outlet temperatures were controlled at 250 °C and 118 °C respectively, the feeding speed was 19.18 mL / min, and the atomizer frequency was 25 Hz. Then, the composite powder was dried at 80 - 90 °C to remove the residual water vapor and then passed through 32 μm and 100 μm sieves, and the powder with a particle size of 32 - 100 μm was collected, that is, the Nano-FeCoNi@SiO2 / CBS composite powder was obtained;

[0068] Step 4: Measurement of particle size and fluidity

[0069] The particle size and fluidity of the composite powder collected in Step 4 were measured by a laser particle size analyzer and a Hall flowmeter respectively. Its D50 was measured to be 65.4 μm by the laser particle size analyzer, and the fluidity was 115 s / 50 g;

[0070] Step 5: Atmospheric plasma spraying

[0071] After removing the oil stain on the surface of the substrate with ethanol, acetone, etc., the substrate is subjected to sandblasting treatment. Then, the sandblasted substrate is fixed in a spraying system composed of a 100HE atmospheric plasma spraying device produced by Progressive Surface Company and a robotic arm of model IRB 2600 produced by ABB Engineering Company. The powder feeding rate is measured to be 13 g / min. The robotic arm program is set to include a distance of 12 cm from the substrate, a step size (mm) of 3*42, a cycle number (non-stop) of 6, etc. After that, the spraying power is set to 35 KW, and the rates of argon, nitrogen, and hydrogen are 4529.6, 2264.8, and 1698.6 L / min respectively. After the settings are completed, the substrate is preheated, and then the bonding layer Ni@Al and the functional layer Nano-FeCoNi@SiO2 / CBS are sprayed successively. The thickness of the bonding layer is 100 μm, and the thickness of the functional layer is 1 mm.

[0072] Example 3

[0073] Step 1: Powder property regulation

[0074] Put 1 kg of CBS powder into a stainless steel ball milling tank, then add 4 kg of 1.0 - 1.2 mm zirconia balls, and ball mill at 500 r / min for 10 h to obtain CBS powder with corresponding particle size for standby.

[0075] Step 2: Composite powder preparation

[0076] Add Nano-FeCoNi powder (without coating modification) to the ball milling tank, and on the basis of controlling the content of Nano-FeCoNi to be 30 vol%, add a certain amount of the CBS powder obtained in Step 1. Then add 2.5% of PVA based on the sum of the masses of Nano-FeCoNi powder and CBS powder, and 0.8% of ammonium citrate based on the sum of the masses of Nano-FeCoNi powder and CBS powder. Add 1.0 - 1.2 mm zirconia balls according to a ball-to-material ratio of 4:1, and roll and stir for 10 h to obtain a slurry; inject the obtained slurry into a spray granulator through a peristaltic pump for spray granulation. The inlet and outlet temperatures are controlled at 250 °C and 118 °C respectively, the feeding speed is 19.18 mL / min, and the atomizer frequency is 25 Hz. Then dry the residual water vapor of the composite powder at 80 - 90 °C and pass it through 32 μm and 100 μm sieves, and collect the powder with a particle size of 32 - 100 μm, that is, obtain Nano-FeCoNi / CBS composite powder;

[0077] Step 3: Measure particle size and fluidity

[0078] The composite powder collected in Step 4 was measured for its particle size and fluidity using a laser particle size analyzer and a Hall flowmeter respectively. The D50 measured by the laser particle size analyzer was 62.3 μm, and the fluidity was 110 s / 50 g;

[0079] Step 4: Atmospheric plasma spraying

[0080] After cleaning the surface oil of the substrate with ethanol, acetone, etc., the substrate was subjected to sandblasting treatment. Then the sandblasted substrate was fixed in a spraying system composed of a 100HE atmospheric plasma spraying device produced by Progressive Surface Company and a robotic arm of model IRB 2600 produced by ABB Engineering Company. The powder feeding rate was measured to be 13 g / min. The robotic arm program was set to include a distance from the substrate of 12 cm, a step size (mm) of 3 * 42, a cycle number (continuous) of 6, etc. After that, the spraying power was set to 35 KW, and the rates of argon, nitrogen, and hydrogen were 4529.6, 2264.8, and 1698.6 L / min respectively. After the settings were completed, the substrate was preheated, and then the bonding layer Ni@Al and the functional layer Nano-FeCoNi / CBS were sprayed successively. The thickness of the bonding layer was 100 μm, and the thickness of the functional layer was 1 mm.

[0081] Comparative Example 1:

[0082] Compared with Example 1, most of them are the same, except that the glass powder is replaced with Al2O3 with a particle size < 5 μm.

[0083] Comparative Example 2:

[0084] Compared with Comparative Example 1, most of them are the same, except that Nano-FeCoNi is replaced with FeSiAl with a particle size < 5 μm.

[0085] From Figure 1 and Figure 2 we can clearly see from the surface morphology of the FeCoNi powder that with the coating of the coating layer, the surface morphology of the powder shows different forms, proving the successful preparation of the core-shell structure. From Figure 3 and Figure 7 it can be seen that as the particle size of the magnetic wave absorber decreases, the magnetic wave absorber can achieve high-volume ratio filling. In Example 1, the volume ratio of Nano-FeCoNi can reach more than 30%. In Comparative Example 4, when the volume ratio of FeSiAl reaches 28%, the coating has achieved local conductivity. From Figure 4 、 5 we can see that as the volume ratio of Nano-FeCoNi increases from 20% to 30%, the dispersion of Nano-FeCoNi in the coating is good and there is no aggregation phenomenon, and no conductive network is formed. From Figure 4 、8 As can be seen, when using low-melting-point CBS glass powder as the binder, due to the "sand and stone effect", Nano-FeCoNi is more likely to maintain a spherical morphology and reduce the flaky structure. From Figure 4 、 6 As can be seen, with the coating of the SiO2 shell layer on the surface of Nano-FeCoNi, the coating structure becomes denser, the wettability of CBS glass powder to Nano-FeCoNi increases, and the coating cracks decrease. From Figure 9 From the phase analysis, when using low-melting-point CBS glass powder as the binder, on the one hand, it reduces the thermal spraying power and the oxidation degree of Nano-FeCoNi. On the other hand, the prior and sufficient melting of CBS forms a protective film on Nano-FeCoNi, which not only reduces the flaky tendency but also improves the oxidation resistance of Nano-FeCoNi.

[0086] Example 4:

[0087] Compared with Example 1, most of them are the same, except that the amount of ethanol is adjusted so that its volume ratio to water is 3:1, the addition amount of ammonia water is adjusted to make the pH of the solution system about 10, and the addition amount of tetraethyl orthosilicate is adjusted to make its concentration in the solution system 0.5%.

[0088] Example 5:

[0089] Compared with Example 1, most of them are the same, except that the amount of ethanol is adjusted so that its volume ratio to water is 6:1, the addition amount of ammonia water is adjusted to make the pH of the solution system about 11, and the addition amount of tetraethyl orthosilicate is adjusted to make its concentration in the solution system 1.5%.

[0090] Example 6:

[0091] Compared with Example 1, most of them are the same, except that in the adjusted obtained slurry, its solid content is 30 wt%, the proportion of nano magnetic alloy powder is 20 vol%, the mass of added PVA is 1% of the sum of the mass of nano magnetic alloy powder and glass powder, and the mass of added ammonium citrate is 0.5% of the sum of the mass of nano magnetic alloy powder and glass powder.

[0092] Example 7:

[0093] Compared with Example 1, most of them are the same, except that in the adjusted powder property control, the addition amount of zirconia balls is 3 kg, and ball milling is carried out for 10 h under the condition of 500 r / min to obtain CBS powder with the corresponding particle size.

[0094] Example 8:

[0095] Compared with Example 1, most of them are the same. Except in the regulation of powder characteristics, the addition amount of zirconia balls is 4 kg, and ball milling is carried out for 10 h under the condition of 300 r / min to obtain CBS powder with corresponding particle size.

[0096] Example 9:

[0097] Compared with Example 1, most of them are the same. Except in the adjusted obtained slurry, the proportion of the nano-magnetic alloy powder is 35 vol%, the mass of PVA added is 5% of the sum of the masses of the nano-magnetic alloy powder and the glass powder, and the mass of ammonium citrate added is 1% of the sum of the masses of the nano-magnetic alloy powder and the glass powder.

[0098] Example 10:

[0099] Compared with Example 1, most of them are the same. Except that the spraying power is adjusted to 30 KW.

[0100] Example 11:

[0101] Compared with Example 1, most of them are the same. Except that the spraying power is adjusted to 55 KW.

[0102] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A preparation method of an antioxidant nano-magnetic alloy @SiO2 / glass composite wave-absorbing coating for thermal spraying, characterized in that, It includes the following steps: (1) Take nano-magnetic alloy powder and disperse it in a mixed solution of ethanol and water. Add ammonia water and mix, then add tetraethyl orthosilicate, react, wash and dry to obtain nano-magnetic alloy@SiO2 composite powder; (2) Take glass powder and add it to a ball milling tank. Add zirconia balls and perform ball milling treatment; (3) Then mix the ball-milled glass powder obtained in step (2) with the obtained nano-magnetic alloy@SiO2 composite powder and add them to a ball milling tank. Then add PVA solution and ammonium citrate, and add zirconia balls. Stir by rolling to obtain a slurry, perform spray granulation, dry and screen to obtain nano-magnetic alloy@SiO2 / glass composite powder; (4) After taking the substrate, cleaning and sandblasting it, use the atmospheric plasma spraying process to spray the bonding layer and the functional layer successively. Among them, the functional layer uses the nano-magnetic alloy@SiO2 / glass composite powder obtained in step (3) as the coating raw material, and that is completed; In step (1), the nano-magnetic alloy powder is magnetic alloy powder Nano-FeCoNi with a Curie temperature > 500 °C; In step (2), the glass powder used is low-melting-point CBS glass powder with a melting range < 500 °C.

2. The preparation method of an antioxidant nano-magnetic alloy @SiO2 / glass composite wave-absorbing coating for thermal spraying according to claim 1, characterized in that, In step (1), the volume ratio of ethanol to water is 3 - 6:1; The addition amount of ammonia water satisfies that the pH of the solution system is 10 - 11; The addition amount of tetraethyl orthosilicate satisfies that its molar concentration in the solution system is 0.5 - 1.5%; 3. The preparation method of an antioxidant nano-magnetic alloy @SiO2 / glass composite wave-absorbing coating for thermal spraying according to claim 1, characterized in that, In step (1), the reaction temperature is room temperature and the reaction time is 6 - 10 h.

4. The preparation method of an antioxidant nano-magnetic alloy @SiO2 / glass composite wave-absorbing coating for thermal spraying according to claim 1, characterized in that, In step (2), during the ball milling process, the ball-to-material ratio is 4 - 10:1, the ball milling speed is 320 - 500 r / min, and the time is 2 - 10 h.

5. The preparation method of an antioxidant nano-magnetic alloy @SiO2 / glass composite wave-absorbing coating for thermal spraying according to claim 1, characterized in that, In step (3), in the obtained slurry, its solid content is 30 - 50 wt%, the proportion of nano-magnetic alloy powder is 20 - 35 vol%, the mass of the added PVA is 1 - 5% of the sum of the masses of the nano-magnetic alloy@SiO2 composite powder and the glass powder, and the mass of the added ammonium citrate is 0.5 - 1% of the sum of the masses of the nano-magnetic alloy@SiO2 composite powder and the glass powder; The addition amount of zirconia balls satisfies: the ball-to-material ratio is 3 - 5:

1.

6. The preparation method of an antioxidant nano-magnetic alloy @SiO2 / glass composite wave-absorbing coating for thermal spraying according to claim 1, characterized in that, In step (3), during the spray granulation process, the inlet and outlet temperatures of the spray granulator are controlled at 250 °C and 118 °C respectively, the feeding speed is 19.18 mL / min, and the atomizer frequency is 25 Hz; The drying temperature is 80 - 90 °C; The screening process is specifically: passing through 32 μm and 100 μm sieves, the amplitude of the vibrating sieve is 80 - 95%, and the vibrating time is 5 - 10 min.

7. The preparation method of an antioxidant nano-magnetic alloy @SiO2 / glass composite wave-absorbing coating for thermal spraying according to claim 1, characterized in that, In step (4), the substrate is 304 stainless steel; The bonding layer is Ni@Al.

8. The preparation method of an antioxidant nano-magnetic alloy @SiO2 / glass composite wave-absorbing coating for thermal spraying according to claim 1, characterized in that, In step (4), during the atmospheric plasma spraying process, the distance between the spray gun nozzle and the substrate is 10 - 15 cm, the powder feeding rate is 10 - 15 g / min, the spraying power is 30 - 55 KW, and the rates of argon, nitrogen, and hydrogen are 4000 - 500 L / min, 2000 - 2500 L / min, and 1500 - 2000 L / min respectively.

9. An antioxidant nano-magnetic alloy @SiO2 / glass composite wave-absorbing coating for thermal spraying, which is prepared by the preparation method described in any one of claims 1-8.

10. Use of an antioxidant nano-magnetic alloy @SiO2 / glass composite wave-absorbing coating for thermal spraying according to claim 9 in the preparation of wave-absorbing materials.

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