A kind of B 4 Controllable modification method for protecting photocathode with C ceramic reinforcement particles

Abstract

A method for controllable modification of photocathode protection of B4C ceramic reinforcement particles. The present invention relates to a method for modifying B4C particles. In order to solve the problems of complex process, harsh conditions and uncontrollable synthesis existing in the preparation method of TiO2 transition layer in existing composite materials. The present invention uses the method of titanate hydrolysis, and uses a blender to fully mix the titanate solution with B4C powder, so that a layer of titanium source is evenly coated on the surface of the B4C powder. After the titanate hydrolysis, uniformly distributed TiO2 particles can be generated on the surface of the B4C powder. And the equipment used in the present invention has the advantages of simple equipment, controllable results, high cost performance, high yield, safety and no environmental pollution, etc. The prepared modified B4C powder can be used to prepare photocathode protection composite materials. The photo-induced TiO2 nanoparticles transition electrons, thereby alleviating the potential difference between the B4C particles and the metal matrix and improving the corrosion resistance of the composite material.

Description

Technical Field

[0001] The present invention relates to a method for modifying B 4 C particles. Background Art

[0002] B 4 C particles are a relatively excellent ceramic reinforcement, with a density (2.52 g / cm 2 ) lower than that of aluminum alloy and a hardness as high as 30 GPa, which is only slightly lower than that of diamond and c-BN. In addition, B 4 C also has high impact resistance, excellent corrosion resistance, and high neutron absorption capacity. Therefore, B 4 C particles are often used to prepare lightweight and high-strength metal matrix composites. However, due to the addition of ceramic particles, the corrosion performance of metal matrix composites often deteriorates. After adding B 4 C particles, multiple sensitive corrosion sites are formed in the composite material. Since there is a potential difference between B 4 C particles and the alloy matrix, a microgalvanic couple can be formed in a corrosive environment, and thus the composite material undergoes electrochemical corrosion. Therefore, constructing an effective corrosion-mitigating transition layer between B 4 C particles and the matrix is the key to improving the corrosion resistance of the composite material.

[0003] TiO 2 is widely used in protective coatings on the surface of materials due to its excellent photocatalytic and optoelectronic properties. Traditional metal corrosion protection methods, such as sacrificial anode protection method and impressed current protection method, have problems such as waste of electric energy and loss of sacrificial anodes. Based on the characteristics of semiconductors such as TiO 2 , photocathode protection is a new method for improving the corrosion performance of materials. The basic principle of photocathode protection is: under illumination, electrons are attracted by the semiconductor, and the photo-generated electrons are transferred to the metal, making its potential value lower than the free corrosion potential to prevent metal corrosion. Currently, TiO 2 is often used to prepare anti-corrosion coatings for materials, but there is almost no application as a transition layer for preparing composite materials.

[0004] In order to form a TiO 2 transition layer in the prepared composite material, it is necessary to pretreat B 4 C particles first. For example, in the patent with the patent number CN201410699031.0 and the invention name "A p-n heterojunction type visible light catalyst B 4 C / TiO 2 and its preparation method", it is pointed out that synthesizing TiO 4 on the surface of B 2 C powder needs to react in a high-temperature reaction kettle for 20 to 28 hours to complete, and this method requires certain temperature and pressure conditions to synthesize TiO2 , the process is complex and time-consuming. The patent with the patent number CN201510317527.1 and the invention title of "Nano Titanium Dioxide and Micro Boron Carbide Composite Polyvinyl Chloride Material and Preparation Method" proposes to use a high-energy ball mill to disperse nano titanium dioxide (TiO 2 ) particles and micro boron carbide (B 4 C) powder. This invention method cannot achieve uniform coating of nano TiO 2 particles on B 4 C powder, and the smaller the nano particle size, the more difficult it is to disperse. The above methods have complex processes, harsh conditions, and are not conducive to the controllable synthesis of TiO 4 particles on the surface of B 2 powder. Summary of the Invention

[0005] The present invention aims to solve the problems of complex process, harsh conditions, and uncontrollable synthesis existing in the preparation method of the TiO 2 transition layer in the existing composite materials, and provides a controllable modification method for the photocathode protection of B 4 C ceramic reinforcement particles. This method is simple to operate and can controllably synthesize TiO 4 particles on the surface of B 2 powder.

[0006] The controllable modification method for the photocathode protection of B 4 C ceramic reinforcement particles of the present invention is carried out according to the following steps:

[0007] 1. Dissolve the titanium source in an alcohol solvent and stir evenly to obtain a light yellow liquid A;

[0008] The stirring process is: stir for 10 - 30 minutes under the condition of a rotation speed of 200 - 500 revolutions per minute;

[0009] The titanium source is tetraethyl titanate or tetrabutyl titanate;

[0010] The volume ratio of the titanium source to absolute ethanol is 1:(5 - 50);

[0011] 2. Under stirring conditions, add B 4 C powder to the light yellow liquid A to obtain a mixed slurry B;

[0012] The molar ratio of B 4 C to Ti element in the light yellow liquid A is (1 - 100):1;

[0013] The particle size of the B 4 C powder is 1 - 100 μm;

[0014] The speed of the stirrer during stirring in step 2 is 280 - 320 revolutions per minute;

[0015] III. Prepare an acid solution, and uniformly titrate the acid solution into the mixed slurry B under stirring conditions, and continue stirring to obtain a mixed slurry C;

[0016] The acid solution is prepared from deionized water, an acid, and an alcohol solvent; the volume ratio of deionized water, the acid, and the alcohol solvent is (0.01 - 0.5):(0.01 - 0.3):1; the acid is glacial acetic acid;

[0017] The volume ratio of the acid solution to the light yellow liquid A is 1:(10 - 20);

[0018] In step III, the titration speed is 1 - 10 drops / second;

[0019] In step III, the stirring speed is 200 - 1000 revolutions per minute;

[0020] In step III, the time for continuous stirring is 100 - 300 minutes;

[0021] IV. Centrifuge the mixed slurry C, and centrifuge and wash the solid product with an alcohol solvent 5 - 10 times, and then filter to obtain the modified B 4 C precipitate particles;

[0022] In step IV, when centrifuging and washing, the speed of the centrifuge is 2000 - 7000 revolutions per minute;

[0023] V. Dry the B 4 C precipitate particles, and then calcine to obtain TiO 2 Particles - coated B 4 C powder;

[0024] The drying process in step V is: drying at 50 - 100 °C for 2 - 10 hours;

[0025] The calcination process in step V is: calcining at 200 - 400 °C and in an air atmosphere for 1 - 5 hours;

[0026] The alcohol solvent mentioned in steps I, III, and IV is absolute ethanol.

[0027] Compared with the existing invention technology, the present invention has the following advantages:

[0028] 1. The present invention uses the method of titanate hydrolysis, and uses a stirrer to fully mix the titanate solution with B 4 C powder, and a layer of titanium source is uniformly coated on the surface of B 4 C powder. After the titanate hydrolyzes, uniformly distributed TiO 4 Particles can be formed on the surface of B 2 C powder.

[0029] 2. The present invention controls the hydrolysis reaction process of the titanate solution by regulating the acid content, thereby better controlling the hydrolysis time and the sol-gel state of the titanate, which is beneficial to the rapid loading of TiO 2 on the surface of B 4 C powder, with short time consumption and high efficiency.

[0030] 3. The present invention can controllably adjust the stirring speed and the titration speed so that water is not concentrated in one area, avoiding the occurrence of a strong hydrolysis reaction to produce a large amount of flocculent reaction products, thereby realizing the nucleation and growth of TiO 2 on the surface of B 4 C powder, with good stability.

[0031] In summary, compared with the prior art, the present invention makes TiO 2 particles evenly distributed on the surface of B 4 C powder by regulating parameters such as acid content, stirring speed and titration speed. Moreover, the equipment used in the present invention has the advantages of simple equipment, controllable results, high cost performance, high yield, safety and no environmental pollution. The prepared modified B 4 C powder can be used to prepare a photocathode protection composite material, and the photoinduced TiO 2 nanoparticles transition electrons, thereby alleviating the potential difference between B 4 C particles and the metal matrix and improving the corrosion resistance of the composite material. Description of the Drawings

[0032] Figure 1 is the scanning electron microscope photograph of the original B 4 C powder;

[0033] Figure 2 is the scanning electron microscope photograph of the modified B 2 C powder in Example 1. 4 C powder. Detailed Embodiments

[0034] The technical solution of the present invention is not limited to the following specific embodiments, and also includes any reasonable combination between the specific embodiments.

[0035] Specific Embodiment 1: The method for controllably modifying the photocathode protection of the B 4 C ceramic reinforcement particles is carried out according to the following steps:

[0036] 1. Dissolve the titanium source in an alcohol solvent and stir evenly to obtain a light yellow liquid A;

[0037] 2. Under stirring conditions, add B 4 C powder to the light yellow liquid A to obtain a mixed slurry B;

[0038] In the light yellow liquid A, B 4The molar ratio of C and Ti elements (1 - 100): 1;

[0039] The said B 4 The particle size of the BC powder is 1 - 100 μm;

[0040] In step two, the speed of the mixer during stirring is 280 - 320 revolutions per minute;

[0041] Third, prepare an acid solution, and uniformly titrate the acid solution into the mixed slurry B under stirring conditions at a titration speed of 1 - 10 drops per second; continue stirring to obtain a mixed slurry C;

[0042] The said acid solution is prepared from deionized water, acid, and an alcohol solvent; the volume ratio of deionized water, acid, and alcohol solvent is (0.01 - 0.5):(0.01 - 0.3):1; the said acid is glacial acetic acid;

[0043] The volume ratio of the said acid solution to the light yellow liquid A is 1:(10 - 20);

[0044] Fourth, centrifuge the mixed slurry C, and centrifuge and wash the solid product 5 - 10 times with an alcohol solvent, and then filter to obtain the modified BC 4 precipitation particles;

[0045] Fifth, dry the BC 4 precipitation particles, and then calcine to obtain TiO 2 particles - coated BC 4 powder.

[0046] This embodiment has the following beneficial effects:

[0047] 1. This embodiment uses the method of titanate hydrolysis, and uses a mixer to fully mix the titanate solution with the BC 4 powder. A layer of titanium source is evenly coated on the surface of the BC 4 powder. After the titanate hydrolysis, TiO 4 particles with uniform distribution can be generated on the surface of the BC 2 powder.

[0048] 2. This embodiment controls the hydrolysis reaction process of the titanate solution by controlling the acid content, so as to better control the hydrolysis time and the sol - gel state of the titanate, which is conducive to the rapid loading of TiO 2 on the surface of the BC 4 powder, with short time consumption and high efficiency.

[0049] 3. This embodiment can controllably adjust the stirring speed and the titration speed so that water is not easily concentrated in one area, avoiding the occurrence of a strong hydrolysis reaction to produce a large amount of flocculent reaction products, thereby realizing the nucleation and growth of TiO 2 on the surface of the BC 4 powder, with good stability.

[0050] In summary, compared with the prior art, in this embodiment, by adjusting parameters such as acid content, stirring speed, and titration speed, TiO 2 particles are evenly distributed on the surface of B 4 C powder. Moreover, the equipment used in this embodiment has the advantages of simple structure, controllable results, high cost performance, high yield, safety, and no environmental pollution. The prepared modified B 4 C powder can be used to prepare a photocathode protection composite material. The photoinduced TiO 2 nanoparticles transfer electrons, thereby alleviating the potential difference between B 4 C particles and the metal matrix and improving the corrosion resistance of the composite material.

[0051] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that the stirring process in Step 1 is as follows: Stir for 10 to 30 minutes under the condition that the rotation speed is 200 to 500 revolutions per minute.

[0052] Specific Embodiment 3: The difference between this embodiment and Specific Embodiment 1 or 2 is that the titanium source in Step 1 is tetraethyl titanate or tetrabutyl titanate.

[0053] Specific Embodiment 4: The difference between this embodiment and any one of Specific Embodiments 1 to 3 is that the volume ratio of the titanium source to absolute ethanol in Step 1 is 1:(5 - 50).

[0054] Specific Embodiment 5: The difference between this embodiment and any one of Specific Embodiments 1 to 4 is that the stirring speed in Step 3 is 200 to 1000 revolutions per minute.

[0055] Specific Embodiment 6: The difference between this embodiment and any one of Specific Embodiments 1 to 5 is that the continuous stirring time in Step 3 is 100 to 300 minutes.

[0056] Specific Embodiment 7: The difference between this embodiment and any one of Specific Embodiments 1 to 6 is that the speed of the centrifuge during centrifugal cleaning in Step 4 is 2000 to 7000 revolutions per minute.

[0057] Specific Embodiment 8: The difference between this embodiment and any one of Specific Embodiments 1 to 7 is that the drying process in Step 5 is as follows: Dry at 50 to 100 °C for 2 to 10 hours.

[0058] Specific Embodiment 9: The difference between this embodiment and any one of Specific Embodiments 1 to 8 is that the calcination process in Step 5 is as follows: Calcinate at 200 to 400 °C in an air atmosphere for 1 to 5 hours.

[0059] Specific Embodiment 10: The difference between this embodiment and any one of Specific Embodiments 1 to 9 is that the alcohol solvent in Steps 1, 3, and 4 is absolute ethanol.

[0060] Example 1:

[0061] In this example B 4 The controllable modification method for photocathode protection of C ceramic reinforcement particles is carried out according to the following steps:

[0062] I. Dissolve the titanium source in absolute ethanol and stir evenly to obtain a light yellow liquid A;

[0063] The stirring process is: stir for 15 minutes under the condition of a rotation speed of 300 revolutions per minute;

[0064] The titanium source is tetrabutyl titanate; the volume ratio of the titanium source to absolute ethanol is 1:25;

[0065] II. Under stirring conditions, add B 4 C powder into the light yellow liquid A to obtain a mixed slurry B; the speed of the stirrer during stirring is 300 revolutions per minute;

[0066] In the light yellow liquid A, the molar ratio of B 4 C to Ti element is 25:1; the B 4 C powder has a particle size of 1 - 10 μm;

[0067] III. Prepare an acid solution, and under stirring conditions, slowly titrate the acid solution into the mixed slurry B at a speed of 2 drops per second while stirring at a speed of 400 revolutions per minute; continue stirring to obtain a mixed slurry C, and the continuous stirring time is 150 minutes;

[0068] In the acid solution, the volume ratio of deionized water, acid, and absolute ethanol is 0.15:0.1:1; the acid is glacial acetic acid;

[0069] The volume ratio of the acid solution to the light yellow liquid A is 1:20;

[0070] IV. Centrifuge the mixed slurry C, and wash the solid product 6 times with absolute ethanol by centrifugation. The speed of the centrifuge during centrifugal washing is 3500 revolutions per minute; filter to obtain the modified B 4 C precipitate particles;

[0071] V. Dry the B 4 C precipitate particles, and then calcine them to obtain B 2 C powder coated with TiO 4 particles (with a particle size of 0.01 - 0.1 μm); the drying process is: dry at 70 °C for 4 hours; the calcination process is: calcine at 350 °C in an air atmosphere for 2 hours.

[0072] Figure 1 is the scanning electron microscope photograph of the original B 4 C powder;Figure 1 It can be seen that B 4 The surface of C powder is relatively smooth and free of impurities; Figure 2 For TiO in Example 1 2 Modified B 4 Scanning electron microscope photograph of C powder Figure 2 It can be seen that B 4 TiO is distributed on the surface of C powder 2 particles. B 4 The surface of C powder is smooth and free of impurities.

[0073] The TiO obtained in Example 1 2 B modified with particles 4 C powder is used to prepare TiO by pressure infiltration 2 @B 4 C / Al composite material. For comparison, B 4 C / Al composite material is also prepared by the same preparation method. B 4 C / Al composite material and TiO 2 @B 4 The content of the reinforcement in the C / Al composite material is 50 vol.%, and the matrix is pure aluminum. Respectively, B 4 C / Al composite material and TiO 2 @B 4 Electrochemical tests under xenon lamp irradiation were carried out on the C / Al composite material. Table 1 gives the corrosion potential (E corr ) and corrosion current density (i corr ). It can be seen from Table 1 that TiO 2 @B 4 The i of the C / Al composite material corr is significantly smaller than that of B 4 C / Al composite material, and E corr is significantly higher than that of B 4 C / Al composite material. This experimental result shows that TiO 2 B modified with particles 4 The corrosion resistance of the composite material prepared from C powder is improved.

[0074] Table 1

[0075] Composite material <![CDATA[E corr (V)]]> <![CDATA[i corr (μA·cm -2 )]]> <![CDATA[B 4 C / Al]]> -0.74 54.33 <![CDATA[TiO 2 @B 4 C / Al]]> -0.71 9.11

[0076] Example 2:

[0077] In this example, B 4 The method for controllable modification of the photocathode protection of C ceramic reinforcement particles is carried out according to the following steps:

[0078] 1. Dissolve the titanium source in absolute ethanol and stir evenly to obtain a pale yellow liquid A;

[0079] The stirring process is as follows: stirring for 20 minutes under the condition of a rotation speed of 200 revolutions per minute;

[0080] The titanium source is tetrabutyl titanate; the volume ratio of the titanium source to absolute ethanol is 1:50;

[0081] Second, under stirring conditions, add B 4 C powder to the light yellow liquid A to obtain a mixed slurry B; the speed of the stirrer during stirring is 300 revolutions per minute;

[0082] In the light yellow liquid A, the molar ratio of B 4 C to Ti element is 60:1; the particle size of the B 4 C powder is 10 - 20 μm;

[0083] Third, prepare an acid solution, and uniformly titrate the acid solution into the mixed slurry B under stirring conditions. The stirring speed is 600 revolutions per minute, and the titration speed is 4 drops per second; continue stirring to obtain a mixed slurry C, and the continuous stirring time is 200 minutes;

[0084] In the acid solution, the volume ratio of deionized water, acid, and absolute ethanol is 0.3:0.2:1; the acid is glacial acetic acid;

[0085] The volume ratio of the acid solution to the light yellow liquid A is 1:10;

[0086] Fourth, centrifuge the mixed slurry C, and wash the solid product 5 times with absolute ethanol by centrifugation. The speed of the centrifuge during centrifugal washing is 6000 revolutions per minute; perform suction filtration to obtain the modified B 4 C precipitate particles;

[0087] Fifth, dry the B 4 C precipitate particles, and then calcine them to obtain B 2 C powder coated with TiO 4 particles (0.1 - 0.2 μm); the drying process is as follows: drying at 75 °C for 6 hours; the calcination process is as follows: calcining at 300 °C under an atmospheric atmosphere for 3 hours.

[0088] This example can obtain B 2 C powder with a smooth surface and no impurities, and TiO 4 particles are distributed on the surface.

[0089] Example 3:

[0090] In this example, the method for controllable modification of the photocathode protection of the B 4 C ceramic reinforcement particles is carried out according to the following steps:

[0091] 1. Dissolve the titanium source in absolute ethanol and stir evenly to obtain a light yellow liquid A;

[0092] The stirring process is as follows: Stir for 20 minutes under the condition of a rotation speed of 400 revolutions per minute;

[0093] The titanium source is tetrabutyl titanate; the volume ratio of the titanium source to absolute ethanol is 1:25;

[0094] 2. Under stirring conditions, add B 4 C powder into the light yellow liquid A to obtain a mixed slurry B; the speed of the stirrer during stirring is 300 revolutions per minute;

[0095] In the light yellow liquid A, the molar ratio of B 4 C to Ti element is 75:1; the particle size of the B 4 C powder is 20 - 50 μm;

[0096] 3. Prepare an acid solution, and under stirring conditions, titrate the acid solution into the mixed slurry B evenly. The stirring speed is 700 revolutions per minute, and the titration speed is 6 drops per second; continue stirring to obtain a mixed slurry C, and the continuous stirring time is 250 minutes;

[0097] In the acid solution, the volume ratio of deionized water, acid, and absolute ethanol is 0.4:0.25:1; the acid is glacial acetic acid;

[0098] The volume ratio of the acid solution to the light yellow liquid A is 1:20;

[0099] 4. Centrifuge the mixed slurry C, and wash the solid product 7 times with absolute ethanol by centrifugation. The speed of the centrifuge during centrifugal washing is 2000 revolutions per minute; perform suction filtration to obtain the modified B 4 C precipitate particles;

[0100] 5. Dry the B 4 C precipitate particles, and then calcine them to obtain B 2 C powder coated with TiO 4 particles (0.2 - 0.3 μm); the drying process is as follows: Dry at 50 °C for 5 hours; the calcination process is as follows: Calcinate at 400 °C in an atmospheric atmosphere for 3 hours.

[0101] This example can obtain B 2 C powder with a smooth surface and no impurities, and TiO 4 particles are distributed on the surface.

[0102] Example 4:

[0103] In this example, the method for controllable modification of the photocathode protection of B 4 C ceramic reinforcement particles is carried out according to the following steps:

[0104] 1. Dissolve the titanium source in absolute ethanol and stir evenly to obtain a light yellow liquid A;

[0105] The stirring process is as follows: Stir for 22 minutes under the condition that the rotation speed is 400 revolutions per minute;

[0106] The titanium source is tetrabutyl titanate; the volume ratio of the titanium source to absolute ethanol is 1:28;

[0107] 2. Under stirring conditions, add B 4 C powder into the light yellow liquid A to obtain a mixed slurry B; the speed of the stirrer during stirring is 300 revolutions per minute;

[0108] The molar ratio of B 4 C to Ti element in the light yellow liquid A is 80:1; the particle size of the B 4 C powder is 50 - 100 μm;

[0109] 3. Prepare an acid solution, and under stirring conditions, titrate the acid solution into the mixed slurry B evenly. The stirring speed is 900 revolutions per minute, and the titration speed is 7 drops per second; continue stirring to obtain a mixed slurry C, and the time for continuous stirring is 270 minutes;

[0110] The volume ratio of deionized water, acid, and absolute ethanol in the acid solution is 0.5:0.3:1; the acid is glacial acetic acid;

[0111] The volume ratio of the acid solution to the light yellow liquid A is 1:18;

[0112] 4. Centrifuge the mixed slurry C, and wash the solid product with absolute ethanol by centrifugation 7 times. The speed of the centrifuge during centrifugal washing is 4000 revolutions per minute; perform suction filtration to obtain the modified B 4 C precipitate particles;

[0113] 5. Dry the B 4 C precipitate particles, and then calcine them to obtain B 2 C powder coated with TiO 4 particles (0.3 - 0.5 μm); the drying process is as follows: Dry at 75 °C for 3 hours; the calcination process is as follows: Calcinate at 400 °C under an atmospheric atmosphere for 1 hour.

[0114] This example can obtain B 2 C powder with a smooth surface and no impurities, and TiO 4 particles are distributed on the surface.

Claims

1. A method for controllably modifying the photocathode protection of B 4 C ceramic reinforcement particles It is characterized in that: B 4 The controllable modification method for photocathode protection of C ceramic reinforcement particles is carried out according to the following steps:

1. Dissolve the titanium source in absolute ethanol and stir evenly to obtain a light yellow liquid A; The stirring process is: stir for 15 minutes under the condition that the rotation speed is 300 revolutions per minute; The titanium source is tetrabutyl titanate; the volume ratio of the titanium source to absolute ethanol is 1:25; II. Under stirring conditions, add B 4 C powder into the light yellow liquid A to obtain the mixed slurry B; the speed of the stirrer during stirring is 300 revolutions per minute; In the mixed slurry B, B 4 The molar ratio of C and Ti elements is 25:1; the B 4 particle size of the C powder is 1 to 10 μm; 3. Prepare an acid solution, and evenly titrate the acid solution into the mixed slurry B under stirring conditions. The stirring speed is 400 revolutions per minute, and the titration speed is 2 drops per second; continue to stir to obtain a mixed slurry C, and the continuous stirring time is 150 minutes; The volume ratio of deionized water, acid, and absolute ethanol in the acid solution is 0.15:0.1:1; the acid is glacial acetic acid; The volume ratio of the acid solution to the light yellow liquid A is 1:20; IV. Centrifuge the mixed slurry C, and centrifugally wash the solid product with absolute ethanol 6 times. The speed of the centrifuge during centrifugal washing is 3500 revolutions per minute; suction filtration gives the modified B 4 C precipitate particles; 5. B 4 The C precipitate particles are dried and then calcined to obtain TiO 2 Particle-coated B 4 C powder; the drying process is: drying at 70°C for 4 hours; the calcination process is: calcining at 350°C and in an atmospheric atmosphere for 2 hours; The prepared modified B 4 C powder can be used to prepare a photocathode protection composite material, and photo-induced TiO 2 nanoparticles transition electrons, thereby alleviating the potential difference between the B 4 C particles and the metal matrix and improving the corrosion resistance of the composite material.

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