A ternary transition metal boride coating, a method of making and use thereof

Abstract

The present application relates to surface coating preparation technical field, specifically relates to a kind of ternary transition metal boride coating, preparation method and its application, transition metal oxide powder, boron source, inorganic salt and nanoparticle surfactant are mixed and heated to 1000 ℃-1200 ℃, after sufficient reaction, obtain the molten salt containing ternary transition metal boride nanoparticles. Graphite positive electrode and the negative electrode to be deposited are inserted into the molten salt containing ternary transition metal boride nanoparticles, after applying 0.3V / cm-0.7V / cm electric field intensity, ternary transition metal boride nanoparticles in molten salt are assembled to form (M x N 1‑x )B2 ternary transition metal boride coating on the surface of negative electrode under the action of electric field, wherein M and N are independently selected from any one of zirconium, hafnium, niobium, tantalum, and x ranges from 0.1 to 0.9. The present application prepares ternary transition metal boride coating which is full dense and has high bonding strength, and the equipment cost is low and the process operation is simple.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of surface coating preparation, in particular to a ternary transition metal boride coating, a preparation method and application thereof. BACKGROUND

[0002] The ternary transition metal boride coating is favored in the industry field due to its excellent performance, and has great potential application value in the fields of chemical industry, metallurgy, marine engineering and aerospace. The ternary transition metal boride has high melting point, high hardness, good wear resistance and corrosion resistance, and excellent high-temperature oxidation resistance, and can be used to improve the corrosion resistance of steel, improve the wear resistance of titanium metal material or improve the high-temperature oxidation resistance of carbon-based materials. The excellent properties of the ternary transition metal boride make it an ideal coating material for protecting the substrate in harsh application environments, especially in application occasions requiring materials to have wear resistance, corrosion resistance and high-temperature stability.

[0003] At present, the preparation methods of the ternary transition metal boride coating mainly include laser cladding, plasma spraying and chemical vapor deposition. Laser cladding is favored due to its high precision and good metallurgical bonding, but has the disadvantages of high cost, low production efficiency and poor coating density. Plasma spraying can achieve high deposition rate, but has the problem of high porosity, which affects the bonding strength of the coating and the substrate. The coating prepared by the chemical vapor deposition method is uniform and dense, but the equipment is complex, the cost is high, and the environmental conditions are strict. The problems existing in the present coating preparation methods seriously limit the application range of the ternary transition metal boride coating with excellent performance, and the existing preparation process needs to be improved or a new coating preparation method needs to be developed to realize the low-cost preparation of the ternary transition metal boride coating with high quality.

[0004] In view of the above defects, the present inventors have finally obtained the present application after long-term research and practice. SUMMARY

[0005] The present application aims to solve the problem of how to prepare a ternary transition metal boride coating with full density and excellent bonding strength at low cost, and provides a ternary transition metal boride coating, a preparation method and application thereof.

[0006] In order to achieve the above-mentioned purpose, the present application discloses a preparation method of a ternary transition metal boride coating, comprising the following steps:

[0007] S1, preparing a molten salt containing ternary transition metal boride nanoparticles in a molten salt:

[0008] Mixing transition metal oxide powder, boron source, inorganic salt and nanoparticle surfactant and heating to 1000-1200℃, after reaction, molten salt containing ternary transition metal boride nanoparticles is obtained, the nanoparticle size is 20-100nm;

[0009] S2, preparing ternary transition metal boride coating by electric field induced nano-assembly in nanoparticle-containing molten salt:

[0010] Inserting graphite anode and negative electrode to be deposited into molten salt containing ternary transition metal boride nanoparticles, after applying electric field, ternary transition metal boride nanoparticles in molten salt assemble to form ternary transition metal boride coating on the surface of negative electrode under the action of electric field.

[0011] In step S1, the transition metal oxide is any two of ZrO2, HfO2, Nb2O5 and Ta2O5, the particle size is 50-200nm, and the purity is 99.9%.

[0012] In step S1, the boron source is boron powder or boron carbide powder, the particle size is 0.5-2μm, and the purity is 99.9%.

[0013] In step S1, the inorganic salt is NaCl-KCl-MgCl2 or NaF-AlF3, the purity is all analytical pure, in NaCl-KCl-MgCl2, the molar ratio of NaCl to KCl is 1:1, and the content of MgCl2 is 10-60wt%; in NaF-AlF3, the content of AlF3 is 30-70wt%.

[0014] In step S1, the nanoparticle surfactant is any one or two of Cr2O3, P2O5, Al2O3 and Fe2O3, and the purity is 99.9%.

[0015] In step S1, the molar ratio of boron source to transition metal oxide powder is 2:1-9:1, the total amount of inorganic salt added is 25-40 times the total mass of transition metal oxide powder and boron source, and the nanoparticle surfactant is 1-2% of the total weight of transition metal oxide, boron powder and inorganic salt.

[0016] In step S2, the material of negative electrode to be deposited is any one of low carbon steel, titanium and titanium alloy, molybdenum and molybdenum alloy, graphite and C / C composite material.

[0017] In step S2, the intensity of applied electric field is 0.3-0.7V / cm, and the corresponding voltage is less than the theoretical deposition voltage of electrically active substance in molten salt.

[0018] In step S2, the chemical formula of ternary transition metal boride coating is (M x N1-x )B2, wherein, M and N are independently selected from any one of zirconium, hafnium, niobium, tantalum, and x ranges from 0.1 to 0.9.

[0019] The application further discloses a ternary transition metal boride coating prepared by the preparation method and application of the ternary transition metal boride coating in protection of a base body in a harsh environment.

[0020] For the ternary transition metal boride coating prepared by the electric field induced nano-assembly in the NaCl-KCl-MgCl2 molten salt system, the coating sample is taken out from the molten salt, immersed in deionized water for 20-40 min, then immersed in acetone for 5-10 min to remove water, and then dried for use.

[0021] Compared with the prior art, the application has the following beneficial effects:

[0022] 1. The ternary transition metal boride coating is prepared by using a common high-temperature resistance furnace, and the equipment cost is low compared with the prior art;

[0023] 2. The preparation of the ternary transition metal boride nanoparticles and the coating is simultaneously realized in the high-temperature resistance furnace, so that the process flow is short and the operation is convenient;

[0024] 3. The ternary transition metal boride nanoparticles are synthesized in situ by using transition metal oxides and boron powder as precursors in the molten salt, so that the raw material cost of the ternary transition metal boride coating preparation is effectively reduced;

[0025] 4. The molten salt medium has a purification effect on the surface of the low-carbon steel, titanium metal and graphite base materials, and the surface of the base material does not need to be polished or subjected to other surface pretreatment before the coating preparation. DETAILED DESCRIPTION

[0026] Figure 1 The XRD test result of the NaF-AlF3 salt containing nano (Hf 0.5 Zr 0.5 )B2;

[0027] Figure 2 The XRD test result of the NaF-AlF3 salt containing nano (Hf 0.5 Zr 0.5SEM analysis of B2;

[0028] Figure 3 To prepare graphite anode substrates for field-induced nanoassembly in molten salt (Hf) 0.5 Zr 0.5 XRD analysis of B2 coating;

[0029] Figure 4 To prepare graphite anode substrates for field-induced nanoassembly in molten salt (Hf) 0.5 Zr 0.5 B2 coating cross-sectional appearance diagram;

[0030] Figure 5 On the graphite anode substrate (Hf) 0.5 Zr 0.5 B2 coating section mapping diagram;

[0031] Figure 6 To prepare graphite anode substrates for field-induced nanoassembly in molten salt (Hf) 0.5 Zr 0.5 SEM image of the cross-section of coating B2;

[0032] Figure 7 For (Hf) 0.5 Zr 0.5 Results of dynamic oxidation tests of the B2 coating in air from room temperature to 1500°C. Detailed Implementation

[0033] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0034] Example 1

[0035] Boron powder (average particle size 0.6 μm), zirconium dioxide powder (average particle size 100 nm), and hafnium dioxide powder (average particle size 150 nm) were mixed in a molar ratio of 5:0.5:0.5. The solid inorganic salt was a mixture of sodium fluoride and aluminum fluoride in a molar ratio of 1:1. The nanoparticle surfactant was aluminum oxide, added at 2 wt% of the total weight of the transition metal oxides, boron powder, and inorganic salt. All the above raw materials were mixed and ground in a mortar for 15 min, then added to a graphite crucible. The graphite crucible was then placed in an argon-protected resistance furnace and heated to 1050 °C, held for 3 h, to form (Hf... 0.5 Zr 0.5)B2 nanoparticles with a particle size of 60-120 nm. Then, the graphite anode and the graphite cathode were inserted into the NaF-AlF3 melt containing the nanoparticles, and the electric field intensity was selected as 0.5 V / cm, and the corresponding voltage was 1.2 V. The electric field-induced nano-assembly was carried out by applying a voltage for 60 min. After the voltage was applied, the (Hf 0.5 Zr 0.5 )B2 coated graphite cathode was taken out and immersed in a molten NaCl-KCl at 680 ℃ for 8 min to remove the solid salt residues on the surface of the coating. Then, the (Hf 0.5 Zr 0.5 )B2 coated graphite cathode was immersed in deionized water for 25 min, and then immersed in acetone for 6 min to remove the water, and dried to obtain a dense (Hf 0.5 Zr 0.5 )B2 coating.

[0036] Figure 1 and Figure 2 are the XRD and SEM test analysis results of the NaF-AlF3 salt containing the nano (Hf 0.5 Zr 0.5 )B2 after being dipped and cooled and washed with water. Figure 1 and Figure 2 indicate that the nano (Hf 0.5 Zr 0.5 )B2 particles with a particle size of 60-120 nm were synthesized in the melt. Figure 3 is the XRD analysis result of the (Hf 0.5 Zr 0.5 )B2 coating on the prepared graphite cathode, which indicates that the (Hf 0.5 Zr 0.5 )B2 coating was obtained by the electric field-induced nano-assembly in the melt.

[0037] Figure 4 and Figure 5 are the cross-sectional appearance diagram and the corresponding mapping test diagram of the (Hf 0.5 Zr 0.5 )B2 coating on the graphite cathode. From Figure 4 and Figure 5 , it can be seen that the coating can completely wrap the surface of the coating, and the thickness of the coating is basically uniform, and the Zr and Hf elements in the coating are uniformly distributed.

[0038] Figure 6 are the SEM diagrams of the prepared (Hf 0.5 Zr 0.5 )B2 coating. From the diagrams, it can be seen that the coating is a full dense coating without pores, which can be observed by gradually magnifying the coating structure.

[0039] Figure 7 (Hf 0.5 Zr 0.5 )B2coating. Below 600°C, the mass of the coating remained relatively stable, which indicated that the coating was almost not oxidized. Above 600°C, the mass of the coating began to increase, which indicated that the coating reacted with oxygen to form an oxide solid solution containing HfO2and ZrO2to protect the substrate from oxidation.

[0040] Example 2

[0041] The boron powder (average particle size 1 μm), niobium pentoxide powder (average particle size 120 nm) and hafnium dioxide powder (average particle size 150 nm) were mixed in a molar ratio of 6:0.5:1. The solid inorganic salt was a mixed salt of sodium chloride, potassium chloride and magnesium chloride in a molar ratio of 1:1:0.3. The nanoparticle surfactant was chromium sesquioxide, and the amount added was 1.5 wt% of the total weight of the transition metal oxide, boron powder and inorganic salt. After all the raw materials were mixed and ground in a mortar for 12 min, they were all added to a graphite crucible. The graphite crucible was then placed in an argon-protected resistance furnace and heated to 1100°C for 4 h to form a (Hf 0.67 Nb 0.33 )B2nanoparticle-stabilized molten salt with a nanoparticle size of 80-110 nm. The graphite anode and the industrial pure titanium cathode were then inserted into the nanoparticle-containing NaCl-KCl-MgCl2molten salt, and the electric field strength was selected to be 0.55 V / cm, and the corresponding voltage was 1.1 V. The electric field-induced nanoassembly was carried out by applying a voltage for 40 min, and then the voltage was turned off. The industrial pure titanium cathode with the (Hf 0.67 Nb 0.33 )B2coating was then immersed in deionized water for 30 min, and then immersed in acetone for 7 min to remove water, and dried to obtain a dense (Hf 0.67 Nb 0.33 )B2coating with a thickness of 90 μm.

[0042] Example 3

[0043] The boron carbide powder (average particle size 1.2 μm), the niobium pentoxide powder (average particle size 110 nm) and the tantalum pentoxide powder (average particle size 130 nm) are mixed in a molar ratio of 2:0.5:0.5. The solid inorganic salt is a mixed salt of sodium fluoride and aluminum fluoride in a molar ratio of 1.2:1. The nanoparticle surfactant is ferric oxide, and the amount added is 1.6 wt% of the total weight of the transition metal oxide, boron carbide powder and inorganic salt. After all the above raw materials are mixed and ground in a mortar for 20 min, they are all added to a graphite crucible. The graphite crucible is then placed in an argon-protected resistance furnace and heated to 1020 °C, and held for 5 h to form a (Nb 0.5 Ta 0.5 )B2 nanoparticle-stabilized molten salt with nanoparticle particle sizes of 80-120 nm. The graphite anode and the metal molybdenum cathode are then inserted into the nanoparticle-containing NaF-AlF3 molten salt, and an electric field intensity of 0.6 V / cm is selected, corresponding to a voltage of 1.0 V. The electric field-induced nanoassembly is carried out by applying a voltage for 70 min, and then the voltage is removed and the metal molybdenum cathode with the (Nb 0.5 Ta 0.5 )B2 coating is removed and immersed in molten NaCl-KCl at 690 °C for 7 min to remove the solid salt residue on the surface of the coating. The metal molybdenum cathode with the (Nb 0.5 Ta 0.5 )B2 coating is then immersed in deionized water for 30 min, and then immersed in acetone for 8 min to remove the water, and dried to obtain a dense (Nb 0.5 Ta 0.5 )B2 coating with a thickness of 95 μm.

[0044] The above description is merely preferred embodiments of the present application, only to illustrate but not limit the present application. Those skilled in the art understand that many changes, modifications, and even equivalents can be made to the present application within the spirit and scope of the claims of the present application, but all will fall within the protection scope of the present application.

Claims

1. A method of producing a ternary transition metal boride coating, characterized in that, It comprises the following steps: S1, preparing molten salt containing ternary transition metal boride nanoparticles by reaction in molten salt: Mixing transition metal oxide powder, boron source, inorganic salt and nanoparticle surfactant and heating to 1000-1200℃, after reaction, molten salt containing ternary transition metal boride nanoparticles is obtained, and the nanoparticle size is 20-100nm; S2, preparing ternary transition metal boride coating by electric field induced nano-assembly in molten salt containing nanoparticles: Inserting graphite anode and negative electrode to be deposited into molten salt containing ternary transition metal boride nanoparticles, after applying electric field, ternary transition metal boride nanoparticles in molten salt are assembled to form ternary transition metal boride coating on the surface of negative electrode under the action of electric field; In step S1, the nanoparticle surfactant is any one or two of Cr2O3, P2O5, Al2O3 and Fe2O3, and the purity is 99.9%.

2. A method of producing a ternary transition metal boride coating as claimed in claim 1, characterized in that In step S1, the transition metal oxide is any two of ZrO2, HfO2, Nb2O5 and Ta2O5, the particle size is 50-200nm, and the purity is 99.9%.

3. The method of claim 1, wherein the ternary transition metal boride coating is formed by a process comprising: In step S1, the boron source is boron powder or boron carbide powder, the particle size is 0.5-2μm, and the purity is 99.9%.

4. The method for preparing a ternary transition metal boride coating as described in claim 1, characterized in that, In step S1, the inorganic salt is NaCl-KCl-MgCl2 or NaF-AlF3, and the purity is all analytical pure, in the NaCl-KCl-MgCl2, the molar ratio of NaCl to KCl is 1:1, and the content of MgCl2 is 10-60wt%, in the NaF-AlF3, the content of AlF3 is 30-70wt%.

5. The method for preparing a ternary transition metal boride coating as described in claim 1, characterized in that, In step S1, the molar ratio of boron source to transition metal oxide powder is 2:1-9:1, the total amount of inorganic salt added is 25-40 times of the total mass of transition metal oxide powder and boron source, and the nanoparticle surfactant is 1-2wt% of the total weight of transition metal oxide, boron powder and inorganic salt.

6. The method of claim 1, wherein the ternary transition metal boride coating is formed by a process comprising: In step S2, the material of negative electrode to be deposited is any one of low carbon steel, titanium and titanium alloy, molybdenum and molybdenum alloy, graphite and C / C composite material.

7. The method of claim 1, wherein the ternary transition metal boride coating is formed by a process comprising: depositing a first layer of a first ternary transition metal boride on the substrate; and depositing a second layer of a second ternary transition metal boride on the first layer. In step S2, the intensity of applied electric field is 0.3-0.7V / cm, and the corresponding voltage is less than the theoretical deposition voltage of electrically active substance in molten salt.

8. A ternary transition metal boride coating produced by the method of any one of claims 1 to 7, characterized in that The ternary transition metal boride coating has a chemical formula of (M x N 1-x )B2, wherein M and N are independently selected from any one of zirconium, hafnium, niobium, and tantalum, and x ranges from 0.1 to 0.

9.

9. Application of ternary transition metal boride coating in harsh environment substrate protection according to claim 8.

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