CN117779002A - Corrosion-resistant coating, modified titanium material, preparation method and application thereof - Google Patents
Corrosion-resistant coating, modified titanium material, preparation method and application thereof Download PDFInfo
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- CN117779002A CN117779002A CN202211152857.6A CN202211152857A CN117779002A CN 117779002 A CN117779002 A CN 117779002A CN 202211152857 A CN202211152857 A CN 202211152857A CN 117779002 A CN117779002 A CN 117779002A
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- 238000000576 coating method Methods 0.000 title claims abstract description 81
- 239000011248 coating agent Substances 0.000 title claims abstract description 78
- 238000005260 corrosion Methods 0.000 title claims abstract description 67
- 230000007797 corrosion Effects 0.000 title claims abstract description 67
- 150000003608 titanium Chemical class 0.000 title claims description 37
- 239000000463 material Substances 0.000 title claims description 26
- 238000002360 preparation method Methods 0.000 title abstract description 7
- 239000010936 titanium Substances 0.000 claims abstract description 104
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 71
- 229910052751 metal Inorganic materials 0.000 claims abstract description 71
- 239000002184 metal Substances 0.000 claims abstract description 67
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 58
- 239000000758 substrate Substances 0.000 claims abstract description 35
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims abstract description 10
- 239000000460 chlorine Substances 0.000 claims abstract description 10
- 229910052801 chlorine Inorganic materials 0.000 claims abstract description 10
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims abstract description 10
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims abstract description 9
- 229910000484 niobium oxide Inorganic materials 0.000 claims abstract description 9
- URLJKFSTXLNXLG-UHFFFAOYSA-N niobium(5+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Nb+5].[Nb+5] URLJKFSTXLNXLG-UHFFFAOYSA-N 0.000 claims abstract description 9
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 claims abstract description 9
- 229910001887 tin oxide Inorganic materials 0.000 claims abstract description 9
- 239000003513 alkali Substances 0.000 claims abstract description 7
- 238000004519 manufacturing process Methods 0.000 claims abstract description 5
- 239000000203 mixture Substances 0.000 claims abstract description 5
- 239000000243 solution Substances 0.000 claims description 39
- 238000000034 method Methods 0.000 claims description 32
- 239000010410 layer Substances 0.000 claims description 25
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 24
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 23
- 239000002243 precursor Substances 0.000 claims description 23
- 239000002346 layers by function Substances 0.000 claims description 22
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical class [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 14
- 239000011247 coating layer Substances 0.000 claims description 10
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 9
- 150000002821 niobium Chemical class 0.000 claims description 9
- 239000011135 tin Substances 0.000 claims description 9
- 229910021626 Tin(II) chloride Inorganic materials 0.000 claims description 8
- 235000006408 oxalic acid Nutrition 0.000 claims description 8
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 6
- 238000005530 etching Methods 0.000 claims description 6
- 239000007772 electrode material Substances 0.000 claims description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 3
- 239000012267 brine Substances 0.000 claims description 3
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims description 3
- 229910001925 ruthenium oxide Inorganic materials 0.000 claims description 2
- WOCIAKWEIIZHES-UHFFFAOYSA-N ruthenium(iv) oxide Chemical compound O=[Ru]=O WOCIAKWEIIZHES-UHFFFAOYSA-N 0.000 claims description 2
- 238000002203 pretreatment Methods 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 abstract description 6
- 230000004888 barrier function Effects 0.000 abstract description 4
- 230000000694 effects Effects 0.000 abstract description 4
- 239000003792 electrolyte Substances 0.000 abstract description 4
- 238000005536 corrosion prevention Methods 0.000 abstract description 2
- 238000012360 testing method Methods 0.000 description 18
- 238000005868 electrolysis reaction Methods 0.000 description 12
- 229910010413 TiO 2 Inorganic materials 0.000 description 10
- 230000003197 catalytic effect Effects 0.000 description 9
- 238000001354 calcination Methods 0.000 description 8
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- 238000004458 analytical method Methods 0.000 description 7
- 238000001035 drying Methods 0.000 description 7
- 238000005979 thermal decomposition reaction Methods 0.000 description 7
- 229910052718 tin Inorganic materials 0.000 description 7
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 6
- 230000002378 acidificating effect Effects 0.000 description 6
- 239000010955 niobium Substances 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- 150000003303 ruthenium Chemical class 0.000 description 6
- 150000003839 salts Chemical class 0.000 description 6
- 229910006404 SnO 2 Inorganic materials 0.000 description 5
- 229910052758 niobium Inorganic materials 0.000 description 5
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
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- 239000011780 sodium chloride Substances 0.000 description 3
- 238000012876 topography Methods 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 230000001476 alcoholic effect Effects 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- ZOMNIUBKTOKEHS-UHFFFAOYSA-L dimercury dichloride Chemical class Cl[Hg][Hg]Cl ZOMNIUBKTOKEHS-UHFFFAOYSA-L 0.000 description 2
- 238000000635 electron micrograph Methods 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- QWPPOHNGKGFGJK-UHFFFAOYSA-N hypochlorous acid Chemical compound ClO QWPPOHNGKGFGJK-UHFFFAOYSA-N 0.000 description 2
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- 230000001590 oxidative effect Effects 0.000 description 2
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
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- 239000013543 active substance Substances 0.000 description 1
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Abstract
The invention relates to the field of metal corrosion prevention, in particular to a corrosion-resistant coating, a preparation method thereof and a method for producing chlorine and alkali. The corrosion resistant coating comprises a mixture of titanium oxide, tin oxide and niobium oxide. The corrosion-resistant coating (STN coating for short) is used as a barrier between titanium-based metal and the environment, has strong corrosion resistance in acidity and high surface compactness, and has strong barrier effect on active species or electrolyte generated by anode reaction to reach a metal substrate.
Description
Technical Field
The invention relates to the field of metal corrosion prevention, in particular to a corrosion-resistant coating, a modified titanium material and a preparation method thereof, application of the corrosion-resistant coating and the modified titanium material in an electrode material, an electrode serving as an anode and a method for producing chlorine and alkali.
Background
With the increasing problems of energy shortage and environmental pollution, green pollution-free electrolysis technology is attracting more attention, and an electrode is one of main components of an electrolytic tank as a main place where electrochemical reaction occurs, and a titanium-based anode is one type of electrode material which has been widely used in industrial practice, which benefits from excellent corrosion resistance exhibited by titanium in a severe electrolysis environment, however, corrosion resistance of metal in an acidic or alkaline electrolysis environment is limited at all, and titanium-based metal is still susceptible to serious corrosion in a severe electrolysis environment.
The titanium-based anode commonly used in industry at present is prepared by coating a layer of coating containing active substances on the surface of titanium-based metal by a thermal decomposition method, however, the coating on the surface of the titanium-based anode prepared by the process is often in a crack shape, so that the titanium-based metal is directly exposed to an electrolysis environment, active oxygen species or electrolyte generated in the electrolysis process can directly reach the surface of the titanium-based metal through the crack, the surface of the titanium-based metal is passivated, and the active coating is peeled off due to the action of growth stress of a passivation layer along with the passivation, so that the electrode is deactivated.
Therefore, the search for an effective method to inhibit the passivation process of titanium-based metals is of great importance for improving the life of titanium-based anodes.
Disclosure of Invention
The object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a corrosion resistant coating comprising a mixture of titanium oxide, tin oxide and niobium oxide.
The corrosion-resistant coating (STN coating for short) is used as a barrier between titanium-based metal and the environment, has strong corrosion resistance in acidity and high surface compactness, and has strong barrier effect on active species or electrolyte generated by anode reaction to reach a metal substrate.
In addition, since the coating adopts the concept of multicomponent design, the adaptability to the component design of the functional layer (active catalytic layer) is high, i.e. for the catalytic layer, as long as the components areIncluding SnO 2 、TiO 2 、Nb 2 O 5 At least one of the components is combined with RuO 2 The Ti/STN/catalytic layer structure can be built and applied.
The second aspect of the present invention provides a modified titanium material comprising a titanium-based metal as a substrate and a corrosion-resistant coating layer on the surface of the titanium-based metal, the corrosion-resistant coating layer being the corrosion-resistant coating layer provided by the present invention described above.
A third aspect of the present invention provides a method of preparing a modified titanium material, the method comprising:
(1) Applying a precursor solution to a substrate;
(2) Heat treating the substrate with the precursor solution applied thereto;
wherein the precursor solution is an alcohol solution containing titanium salt, tin salt and niobium salt; the substrate is titanium-based metal.
In a fourth aspect, the present invention provides a modified titanium material prepared by the method described above.
In a fifth aspect, the invention provides the use of the corrosion-resistant coating, modified titanium material described above in an electrode material.
A sixth aspect of the present invention provides an electrode for use as an anode, the electrode comprising a titanium-based metal as a substrate, an intermediate layer and a functional layer, the intermediate layer being located on the surface of the titanium-based metal and the functional layer being located on the intermediate layer, the intermediate layer being the above-mentioned corrosion-resistant coating provided by the present invention.
A seventh aspect of the present invention provides a method of producing chlorine and a base, the method comprising using the electrode of the present invention as described above as an anode, filling an anode chamber with alkali chloride brine, applying a potential difference between the cathode and the anode, and precipitating chlorine on the anode surface of the anode chamber.
Compared with the prior art, the invention has the following advantages:
1. on the premise of ensuring stronger binding force with the titanium substrate, the STN coating effectively forms a physical shielding layer to prevent the penetration of corrosive medium, plays a role in avoiding direct contact between the metal substrate and the corrosive medium, and effectively avoids corrosion of titanium-based metal due to high density of the coating.
2. The STN coating has good conductivity and strong corrosion resistance to the severe acid anode electrolysis environment, and the coating can protect the metal substrate on the basis of not losing the overall conductivity of the electrode by introducing the coating between the metal substrate and the active catalytic layer of the anode of the traditional titanium-based coating, thereby prolonging the service life of the whole electrode.
3. The STN coating of the invention is designed in the idea of mixing multicomponent components, so that the adaptability to the component design of the active catalytic layer is high, i.e. for the catalytic layer, as long as SnO is included therein 2 、TiO 2 、Nb 2 O 5 At least one of the components is combined with RuO 2 The construction of Ti/STN/catalytic layer (functional layer) structure can be realized and the combination of the Ti/STN/catalytic layer (functional layer) structure can be applied.
4. The STN coating adopts the traditional thermal decomposition method, has mature preparation process, simple preparation procedure, low preparation cost and strong adaptability.
Drawings
Fig. 1 is a schematic structural view of a titanium-based coated anode containing an STN coating according to the present invention.
Fig. 2 is a surface topography of the STN coating in example 1 of the present invention.
FIG. 3 shows the results of the potentiodynamic polarization curve test of Ti/STN and pure titanium foil in example 1 of the present invention.
Fig. 4 is a graph of the surface topography of STN coatings of different metal ratios in example 2 of the present invention.
FIG. 5 is a graph showing analysis of surface morphology of Ti/STN cross section in example 3 of the present invention.
FIG. 6 is a graph showing the results of potentiodynamic polarization curve test on electrodes with different coating thicknesses in example 3 of the present invention.
FIG. 7 is a graph comparing the timing current test curves of Ti/STN and Ti in the acidic electrolysis environment in test example 1 of the present invention.
FIG. 8 is a Ti/TiO film prepared in test example 2 of the present invention 2 -RuO 2 (described as Ti/RuTi hereinafter) and Ti/SnO 2 -TiO 2 -Nb 2 O 5 /TiO 2 -RuO 2 (described later as Ti/STN/RuTi) electrodes in 4M NaCl+0.1M HCl.
Detailed Description
The present application is further described in detail below by way of the accompanying drawings and examples. The features and advantages of the present application will become more apparent from the description.
The word "exemplary" is used herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are illustrated in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
In addition, the technical features described below in the different embodiments of the present application may be combined with each other as long as they do not collide with each other.
In a first aspect the invention provides a corrosion resistant coating comprising a mixture of oxides of titanium, tin and niobium.
In the present invention, the molar ratio of titanium oxide, tin oxide and niobium oxide in terms of metal element is (50-70): (15-25): (15-25), preferably (55-65): (17.5-22.5): (17.5-22.5).
According to a preferred embodiment of the invention, the corrosion-resistant coating consists of a mixture of titanium oxide, tin oxide and niobium oxide.
The structure of the corrosion-resistant coating provided by the invention is a mixed crystal of titanium oxide, tin oxide and niobium oxide, and the grain boundary density of the coating is improved due to mutual interference in the growth process of three different oxides to inhibit the growth of grains, so that the internal stress in the growth process of the coating is absorbed, and the formation of cracks in the coating is inhibited, thereby constructing a compact crack-free corrosion-resistant coating.
The second aspect of the invention provides a modified titanium material, which comprises a titanium-based metal serving as a substrate and a corrosion-resistant coating layer positioned on the surface of the titanium-based metal, wherein the corrosion-resistant coating layer is the corrosion-resistant coating layer provided by the invention.
In the modified titanium material of the invention, the thickness of the corrosion-resistant coating is 90-400nm.
A third aspect of the present invention provides a method of preparing a modified titanium material, the method comprising:
(1) Applying a precursor solution to a substrate;
(2) Heat treating the substrate with the precursor solution applied thereto;
wherein the precursor solution is an alcohol solution containing titanium salt, tin salt and niobium salt; the substrate is titanium-based metal.
In the present invention, in the precursor solution, the molar ratio of the titanium salt, tin salt, and niobium salt in terms of metal element may be (50 to 70): (15-25): (15-25), preferably (55-65): (17.5-22.5): (17.5-22.5).
In the present invention, the total molar concentration in terms of metal element in the precursor solution may be 0.06 to 0.2M, preferably 0.06 to 0.1M.
In the present invention, the titanium salt is selected from C 16 H 36 O 4 Ti and C 10 H 14 O 5 At least one of Ti, preferably C 16 H 36 O 4 Ti。
In the present invention, the tin salt is selected from SnCl 2 、SnCl 4 And C 10 H 14 O 4 At least one of Sn, preferably SnCl 2 。
In the present invention, the niobium salt is selected from NbCl 5 And (NH) 4 ) 3 [NbO(C 2 O 4 ) 3 ]At least one of them is preferably NbCl 5 。
In the present invention, the alcohol is selected from at least one of methanol, ethanol and isopropanol.
In the present invention, the substrate may be a series of metal materials prepared based on titanium metal, for example, at least one selected from titanium foil, titanium mesh, titanium fiber mat, titanium mesh, and titanium foam.
In the method for producing a modified titanium material of the present invention, the conditions for the heat treatment in step (2) include at least: the temperature is 420-500 ℃, preferably 450-470 ℃; the time is 0.05-1 hour, preferably 0.06-1 hour. The temperature of the heat treatment generally corresponds to the temperature at which the precursor titanium, tin and niobium salts complete thermal decomposition while forming the relevant oxide.
In the present invention, steps (1) and (2) are repeated until the thickness of the corrosion-resistant coating reaches 90 to 400nm. Preferably, in the modified titanium material, the thickness of the corrosion-resistant coating is 100-300nm. After repeating steps (1) and (2) a number of times, the last heat treatment is preferably carried out for at least 1 hour.
In the present invention, the application may be performed in various ways as long as the precursor solution can be uniformly adhered to the substrate, for example, a dipping method may be used in which the substrate is completely immersed in the precursor solution and maintained for a period of time, for example, 10 seconds to 30 seconds.
When the method is applied, the concentration of metal ions in the precursor solution is high, and the application times are low; the concentration is small, the application times are large, and the method is flexible to use in operation.
The substrate with the precursor solution applied thereto may be dried prior to the heat treatment, and the drying may be performed in a conventional manner in the art.
In the method for producing a modified titanium material of the present invention, the substrate may be subjected to a pretreatment including etching with oxalic acid, prior to the step (1). The titanium-based metal surface etched by oxalic acid is rough and rough, grey and loses metallic luster. The pretreatment process may include, for example, immersing the titanium material in an oxalic acid solution and treating at a predetermined temperature for 2 to 3 hours.
In the present invention, the oxalic acid concentration may be 14-20 wt%, and the etching conditions include at least: the temperature can be 85-95 ℃ and the time can be 2-3 hours.
According to a preferred embodiment of the present invention, the method for preparing a modified titanium material comprises the steps of:
(a) Pretreating a substrate, including etching with oxalic acid;
(b) Applying a precursor solution to the pretreated substrate;
(c) Heat treating the substrate with the precursor solution applied thereto;
repeating steps (b) and (c) until the thickness of the corrosion-resistant coating reaches 90-400nm.
In a fourth aspect, the present invention provides a modified titanium material prepared by the above method.
In a fifth aspect, the present invention provides the use of the corrosion-resistant coating, modified titanium material of the present invention as described above in an electrode material.
A sixth aspect of the present invention provides an electrode for use as an anode, the electrode comprising a titanium-based metal as a substrate, an intermediate layer and a functional layer, the intermediate layer being located on the surface of the titanium-based metal and the functional layer being located on the intermediate layer, the intermediate layer being the above-mentioned corrosion-resistant coating provided by the present invention.
In the present invention, the functional layer is a layer functioning as a catalyst in the electrode. The component of the functional layer is not particularly limited as long as it can perform a desired catalytic function, and may be selected conventionally in the art. For example, the functional layer of the present invention includes a combination of ruthenium oxide and at least one of titanium oxide, tin oxide, and niobium oxide. According to a specific embodiment, the functional layer of the invention comprises TiO 2 And RuO (Ruo) 2 。
In the present invention, the functional layer may be coated on the corrosion-resistant coating layer of the modified titanium material by a thermal decomposition method, which is a method widely used in the art. According to a specific embodiment, an electrode comprising a titanium-based metal, an intermediate layer and a functional layer may be manufactured by: applying an alcoholic solution containing a titanium salt, a tin salt and a niobium salt to a titanium-based metal as a substrate, and performing a heat treatment (i.e., oxidative thermal decomposition) to obtain a corrosion-resistant coating; subsequently, a solution containing a metal salt corresponding to the functional layer is applied to the corrosion-resistant coating, and the functional layer is obtained by heat treatment (i.e., oxidative thermal decomposition).
According to a specific embodiment of the invention, the solution of the metal salt corresponding to the functional layer is an alcoholic solution comprising a titanium salt and a ruthenium salt.
In the present invention, in the solution of the metal salt corresponding to the functional layer, the molar ratio of the titanium salt to the ruthenium salt in terms of the metal element may be 1:0.1-0.2.
In the present invention, the total molar concentration in terms of metal element in the solution of the metal salt corresponding to the functional layer may be 0.1 to 0.6M.
In the present invention, the titanium salt is selected from C 16 H 36 O 4 Ti and C 10 H 14 O 5 At least one of Ti, preferably C 16 H 36 O 4 Ti。
In the present invention, the ruthenium salt is selected from RuCl 3 、(NH 4 ) 2 RuCl 6 And C 15 H 21 O 6 At least one of Ru, preferably RuCl 3 。
In the present invention, the alcohol in the solution of the metal salt corresponding to the functional layer may be at least one of methanol, ethanol, and isopropanol.
In the present invention, the conditions of the heat treatment after applying the solution containing the metal salt corresponding to the functional layer to the corrosion-resistant coating may include: the temperature is 450-470 ℃; the time is 0.5-1 hour. The temperature of the heat treatment generally corresponds to the temperature at which the precursor titanium and ruthenium salts complete thermal decomposition while forming the relevant oxide.
A seventh aspect of the present invention provides a method of producing chlorine and a base, the method comprising using the above electrode provided by the present invention as an anode, filling an anode chamber with alkali chloride brine, applying a potential difference between the cathode and the anode, and precipitating chlorine on the anode surface of the anode chamber.
The invention is further illustrated by the following examples, but is not limited thereto.
In the examples and comparative examples,
titanium foil is purchased from the star flagship with the trademark TA1 TA2;
C 16 H 36 O 4 ti was purchased from alfa elsha under the brand 077124;
SnCl 2 purchased from alaa Ding Shiji under the trade designation T121824;
NbCl 5 purchased from enokie under the trade designation a81205;
DSA electrodes were purchased from beijing chemical mechanical factory;
the remaining reagents are all commercially available.
Example 1
(1) Pretreatment of
Etching the titanium foil with 14wt% oxalic acid at 85-95 deg.c for 2-3 hr, ultrasonic treating in deionized water for 15-20min, stoving for 5-10min to obtain clean titanium foil.
(2) Coating STN coating on the surface of titanium-based metal to obtain Ti/SnO 2 -TiO 2 -Nb 2 O 5 (abbreviated as Ti/STN).
(2-1) mixing the C with the metal of titanium, tin and niobium in a molar ratio of 60:20:20 16 H 36 O 4 Ti、SnCl 2 、NbCl 5 Dissolving in ethanol to give C 16 H 36 O 4 Ti concentration is 0.12M, snCl 2 At a concentration of 0.04M, nbCl 5 The concentration was 0.04M. A dip having a total molar concentration of 0.2M in terms of metal element was obtained.
(2-2) the cleaned titanium foil was completely immersed in the prepared dip, maintained for 20 seconds, and transferred to a blow drying oven at 80 ℃.
(2-3) the titanium foil dried in the step (2-2) is placed in a muffle furnace at 450 ℃ for calcination for 5min.
(2-4) repeating steps (2-2) and (2-3) 10 times, and finally prolonging the calcination time in the muffle furnace to 1h. The final STN coating had a thickness of 330nm. The STN coating is subjected to morphology characterization, a scanning electron microscope is adopted for surface morphology analysis, the equipment model is FE-JSM-6701F, and the result is shown in figure 2, so that the surface of the STN intermediate layer presents a crack-free compact morphology.
(2-5) the Ti/STN obtained in step (2-4) was subjected to an electrokinetic polarization curve test, and titanium foil, and other single component coating samples, i.e., ti/Ti, ti/Sn and Ti/Nb, were used as comparative samples to verify the corrosion resistance of the STN coating. The test adopts a three-electrode system, wherein the counter electrode is a DSA electrode, the reference electrode is a saturated calomel electrode, and the working electrode is a metal electrodeThe electrolyte system was tested at 0.1MHClO with an extremely Ti/STN 4 The test potential interval is the open circuit potential + -150 mV. As shown in FIG. 3, analysis shows that the corrosion potential of Ti/STN is increased by 0.6V relative to that of titanium foil, the corrosion current is reduced by two orders of magnitude, and compared with a single-component coating sample, the corrosion potential is also increased, the corrosion current is also reduced, and the corrosion resistance of the electrode is obviously improved by the STN coating.
(3) Ti/STN is taken as a substrate, and RuTi coating is coated on the substrate to obtain Ti/SnO 2 -TiO 2 -Nb 2 O 5 /TiO 2 -RuO 2 (abbreviated as Ti/STN/RuTi).
(3-1) the molar ratio of titanium to ruthenium is 80:20, titanium salt C 16 H 36 O 4 RuCl of Ti and ruthenium salts 3 Dissolved in ethanol to give a titanium salt concentration of 0.16M and a ruthenium salt concentration of 0.04M. A dip having a total molar concentration of 0.2M in terms of metal element was obtained.
(3-2) completely immersing the Ti/STN obtained in the step (2) in the prepared dip, maintaining for 20s, and transferring to a blast drying oven at 80 ℃ for drying.
(3-3) the Ti/STN dried in the step (3-2) is placed in a muffle furnace at 450 ℃ for calcination for 5min.
(3-4) repeating the steps (3-2) and (3-3) 10 times, and finally prolonging the calcination time in the muffle furnace to 1h. Finally obtaining Ti/SnO 2 -TiO 2 -Nb 2 O 5 /TiO 2 -RuO 2 (abbreviated as Ti/STN/RuTi).
Example 2
And coating an STN coating on the surface of the titanium substrate to obtain Ti/STN, and optimizing the proportion of each metal oxide in the coating by regulating and controlling the concentration of different metal elements in the precursor solution.
(1) The molar ratio of titanium to tin to niobium is 50:25: 25. 60:20:20 and 70:15:15, preparing a dipping solution according to the proportion, and adding C 16 H 36 O 4 Ti、SnCl 2 、NbCl 5 Dissolved in ethanol when the metal molar ratio is 50:25:25 times C 16 H 36 O 4 Ti concentration of 0.1M, snCl 2 The concentration is0.05M，NbCl 5 The concentration was 0.05M. When the metal molar ratio is 60:20: at 20, C 16 H 36 O 4 Ti concentration is 0.12M, snCl 2 At a concentration of 0.04M, nbCl 5 The concentration was 0.04M. When the metal mole ratio is 70:15:15 times, C 16 H 36 O 4 Ti concentration of 0.14M, snCl 2 At a concentration of 0.03M, nbCl 5 The concentration was 0.03M. Each of the obtained dips had a concentration of 0.2M in terms of the molar concentration of the metal element Ji Zongma.
(2) The clean titanium foil is respectively immersed into the prepared dipping solutions with different proportions completely, and after the dipping solutions are maintained for 20 seconds, the titanium foil is transferred into a blast drying oven at 80 ℃ for drying.
(3) And (3) placing the titanium foil dried in the step (2) in a muffle furnace at 450 ℃ for calcination for 5min.
(4) Repeating the steps (2) and (3) for 10 times, and prolonging the calcining time in the muffle furnace to 1h for the last time.
(5) The morphology of STN coatings with different proportions is characterized, a Scanning Electron Microscope (SEM) is adopted for surface morphology analysis, the equipment model is FE-JSM-6701F, the result is shown in figure 4, wherein a), b) and c) are respectively titanium, tin and niobium, and the molar ratio of the metals is 50:25: 25. 60:20:20 and 70:15:15, and a surface topography of the STN coating in proportion. Analysis shows that the surface morphology of the coating presents a compact morphology under different set metal ratios, and almost no cracks are generated, which shows that when the metal molar ratio is changed in the interval, the coating can meet the requirement of the electrode on the compact morphology.
Example 3
And coating an STN coating on the surface of the titanium substrate to obtain Ti/STN, and optimizing the thickness of the coating by regulating and controlling the total molar concentration of the metal elements in the precursor solution.
(1) The molar ratio of titanium, tin and niobium is 60:20:20, preparing a dipping solution according to the proportion of C 16 H 36 O 4 Ti、SnCl 2 、NbCl 5 Dissolving in ethanol, and regulating the total molar concentration of the metal elements in the dipping liquid to be 0.02M,0.06M,0.1M and 0.2M respectively.
(2) The clean titanium foil is respectively immersed into the prepared dipping solutions with different proportions completely, and after the dipping solutions are maintained for 20 seconds, the titanium foil is transferred into a blast drying oven at 80 ℃ for drying.
(3) And (3) placing the titanium foil dried in the step (2) in a muffle furnace at 450 ℃ for calcination for 5min.
(4) Repeating the steps (2) and (3) for 10 times, and prolonging the calcining time in the muffle furnace to 1h for the last time.
(5) The relation between the thickness of the coating and the dip concentration was obtained by surface morphology analysis of the Ti/STN cross section, and the analysis result showed that the coating thicknesses were 33nm,99nm,165nm and 330nm when the total molar concentrations of the metal elements were 0.02M,0.06M,0.1M and 0.2M, respectively. As shown in fig. 5.
(6) The electrokinetic potential polarization curve test is carried out on the electrodes with different coating thicknesses, the test conditions are the same as those of the embodiment 1, the test results are shown in fig. 6, the change trend of corrosion potential and corrosion current is analyzed, and when the total molar concentration of metal is 0.02-0.06M, the corrosion resistance is gradually improved along with the increase of the concentration; when the total molar concentration of the metal is 0.06-0.2M, the corrosion resistance tends to be stable. Thus, this example shows that the total molar concentration of metal can be 0.06M to 0.2M.
Comparative example 1
The procedure of example 1 was followed, except that step (2) was not performed, and steps (1) and (3) were performed only, i.e., the resulting clean titanium foil was directly coated with RuTi coating.
Test example 1
Simulating the electrolytic environment of industrial acidic electrolyzed water, and generating 0.1M HClO 4 The corrosion resistance of the STN coating prepared in example 1 was evaluated in a three electrode system (commercial DSA mesh as counter electrode, saturated calomel electrode as reference electrode, ti/STN as working electrode, 0.1M HClO was used) 4 As electrolyte solution), the evaluation test was a chronoamperometric test method, the operating potential was set at 3.3V (vs. rhe), and as a comparison, a pure titanium material was also tested under the same conditions.
FIG. 7 is a graph comparing the timing current test curves of Ti/STN (c) and Ti (a) in an acidic electrolysis environment as described in this test example. In fig. 7 (a) it is evident that the current density increases sharply in a very short time, due to the reaction of the metallic titanium surface being rapidly oxidized, illustrating its extremely poor corrosion resistance in an acidic environment; the electron micrograph of fig. 7 (b) shows significant corrosion. The current density in fig. 7 (c) was always at a lower level and was always stable, indicating that almost no charge transfer process by any corrosion reaction occurred at the coating surface; the electron micrograph of fig. 7 (d) shows that little corrosion occurs. This demonstrates that the introduction of STN corrosion resistant coatings has a significant effect on the improvement of corrosion resistance of titanium-based metals in acidic electrolytic environments.
Test example 2
The stability of the two electrodes prepared in example 1 and comparative example 1 in chlorine evolution reaction was evaluated in 4M NaCl+0.1M HCl and the test current density was 100 mA.cm -2 。
FIG. 8 is a graph showing the time-based potential test of chlorine evolution reaction of Ti/RuTi and Ti/STN/RuTi electrodes in 4M NaCl+0.1MHCl, wherein the anode potential (vs. RHE) of the Ti/RuTi electrode without the corrosion-resistant coating is increased by 50mV after 14-15 h of electrolysis, and the anode potential (vs. RHE) of the Ti/STN/RuTi electrode after the STN corrosion-resistant coating is increased by 50mV after 55-60 h of electrolysis, which shows that the introduction of the STN corrosion-resistant coating has a remarkable effect of prolonging the service life of the Ti-based RuTi electrode in chlor-alkali industrial electrolysis.
The present application has been described in connection with the preferred embodiments, but these embodiments are merely exemplary and serve only as illustrations. On the basis of this, many alternatives and improvements can be made to the present application, which fall within the scope of protection of the present application.
Claims (13)
1. A corrosion resistant coating comprising a mixture of titanium oxide, tin oxide and niobium oxide.
2. The corrosion-resistant coating according to claim 1, wherein the molar ratio of titanium oxide, tin oxide and niobium oxide, calculated as metal element, is (50-70): (15-25): (15-25), preferably (55-65): (17.5-22.5): (17.5-22.5).
3. A modified titanium material, characterized in that the modified titanium material comprises a titanium-based metal as a substrate and a corrosion-resistant coating layer on the surface of the titanium-based metal, wherein the corrosion-resistant coating layer is the corrosion-resistant coating layer according to claim 1 or 2.
4. A modified titanium material as claimed in claim 3, wherein the corrosion resistant coating has a thickness of 90-400nm.
5. A method of preparing a modified titanium material, the method comprising:
(1) Applying a precursor solution to a substrate;
(2) Heat treating the substrate with the precursor solution applied thereto;
wherein the precursor solution is an alcohol solution containing titanium salt, tin salt and niobium salt; the substrate is titanium-based metal.
6. The method according to claim 5, wherein in the precursor solution, a molar ratio of titanium salt, tin salt and niobium salt in terms of metal element is (50-70): (15-25): (15-25), preferably (55-65): (17.5-22.5): (17.5-22.5);
preferably, the total molar concentration in terms of metal element in the precursor solution is 0.1 to 0.3M;
preferably, the titanium salt is selected from C 16 H 36 O 4 Ti and C 10 H 14 O 5 At least one of Ti;
preferably, the tin salt is selected from SnCl 2 、SnCl 4 And C 10 H 14 O 4 At least one of Sn;
preferably, the niobium salt is selected from NbCl 5 And (NH) 4 ) 3 NbO(C 2 O 4 ) 3 ]At least one of (a) and (b);
preferably, the alcohol is selected from at least one of methanol, ethanol and isopropanol.
7. The method of claim 5, wherein the conditions of the heat treatment in step (2) include at least: the temperature is 420-500 ℃, preferably 450-470 ℃; the time is 0.05-1 hour, preferably 0.06-1 hour;
preferably, steps (1) and (2) are repeated until the corrosion-resistant coating thickness reaches 90-400nm.
8. The method of claim 5, wherein prior to step (1), the substrate is pre-treated, the pre-treatment comprising etching with oxalic acid;
preferably, the oxalic acid concentration is 14-20 wt%, and the etching conditions at least comprise: the temperature is 85-95 ℃ and the time is 2-3 hours.
9. A modified titanium material produced by the method of any one of claims 5-8.
10. Use of the corrosion resistant coating of claim 1 or 2, the modified titanium material of claim 3, 4 or 9 in an electrode material.
11. An electrode for use as an anode, characterized in that it comprises a titanium-based metal as a substrate, an intermediate layer on the surface of the titanium-based metal, and a functional layer on the intermediate layer, the intermediate layer being the corrosion-resistant coating according to claim 1 or 2.
12. The electrode of claim 11, wherein the functional layer is a combination of ruthenium oxide and at least one of titanium oxide, tin oxide, and niobium oxide.
13. A method for producing chlorine and alkali, characterized in that the electrode according to claim 11 or 12 is used as an anode, alkali chloride brine is filled in the anode chamber, a potential difference is applied between the cathode and the anode, and chlorine is deposited on the anode surface of the anode chamber.
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