Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C14/00—Alloys based on titanium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
  • C22F1/18—High-melting or refractory metals or alloys based thereon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
  • C22F1/18—High-melting or refractory metals or alloys based thereon
  • C22F1/183—High-melting or refractory metals or alloys based thereon of titanium or alloys based thereon
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
  • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
  • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
  • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
  • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
  • C25B11/055—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material
  • C25B11/057—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material consisting of a single element or compound
  • C25B11/061—Metal or alloy
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working

Definitions

• the present disclosure relates to a titanium alloy plate for an electrode used for an electrode of an electrolytic cell in electrolysis such as soda electrolysis, water electrolysis, industrial electrolysis accompanied by generation of oxygen or chlorine, for example.
• Titanium-based anodes are widely used in various electrolysis processes including soda electrolysis in which Na chloride aqueous solution is electrolyzed to produce Na hydroxide, chlorine gas, and hydrogen gas. Specifically, after processing a pure titanium base material (titanium plate) into a shape having a large number of holes such as an expanded metal or a punched perforated plate, an electrode catalyst component composed of a platinum group metal and its oxide is formed on the surface. The electrode material for anodes which formed the electrode catalyst layer to contain is used.
• an oxide film existing between the pure titanium surface and the electrode catalyst layer becomes a resistance and reduces electrolytic efficiency. If this electrical resistance can be lowered, the electrolytic efficiency can be improved, that is, the amount of power used can be reduced, and the cost can be reduced.
• Patent Document 1 as a base material, at least one element selected from the first group consisting of aluminum, niobium, chromium, manganese, molybdenum, ruthenium, tin, tantalum, vanadium, and zirconium, nickel, cobalt
• an anode capable of improving characteristics such as energy consumption by using a titanium alloy containing at least one element selected from the second group consisting of iron, copper, and palladium, and palladium.
• Patent Document 2 a base material containing at least one metal selected from titanium, tantalum, niobium, zirconium, hafnium and nickel or an alloy thereof and an electrode catalyst component having a predetermined composition are used.
• a method for producing an electrode for electrolysis is disclosed in which the electrode performance is not lowered even if the amount of the electrode catalyst component used is reduced by applying the coating under the predetermined conditions.
• the embodiment of the present invention has been made in view of such a situation, and is a plate material that can be used for an electrode base material, and can reduce electric resistance when an electrode catalyst layer is formed on the surface.
• An object of the present invention is to provide a plate material for an electrode in which an electrode using this substrate can realize high electrolysis efficiency.
• the titanium alloy plate for electrodes according to the embodiment of the present invention can be used as a base material for electrodes.
• the electrode titanium alloy plate includes at least one of Al: 0.1 to 1.0 mass% and Si: 0.1 to 1.0 mass%, and the total content of Al and Si is 0.2 to 1 0.0 mass%, the balance is made of Ti and inevitable impurities, and the average particle size is 5 to 20 ⁇ m.
• a titanium alloy substrate for an electrode according to an embodiment of the present invention has an oxide film containing at least one of Al and Si on the surface, and the total content of Al and Si in the oxide film is 0.08 to 0.55. It is preferable that it is mass%.
• the titanium alloy plate for an electrode according to an embodiment of the present invention can be used as a base material for an electrode, and the electric resistance can be lowered when an electrode catalyst layer is formed on the surface thereof. For this reason, when it uses for an electrode, high electrolysis efficiency can be obtained.
• titanium is an extremely active metal, a new oxide film is immediately formed even if the oxide film present on the surface of pure titanium or a titanium alloy plate is removed. Therefore, when an electrode is manufactured by using pure titanium or a titanium alloy as a base material and an electrode catalyst layer is provided on the surface, an oxide film is formed between the metal portion of the pure titanium or titanium alloy of the base material and the contact layer. It is difficult to avoid intervening.
• the present inventors presuppose that an oxide film is present on the surface of the base material, and when the electrode catalyst layer is provided on the surface of the base material, the electricity between the base material and the electrode catalyst layer is A method for lowering the resistance (for example, contact resistance) was intensively studied.
• the resistance for example, contact resistance
• at least one of Al: 0.1 to 1.0 mass% and Si: 0.1 to 1.0 mass% is included, and the total of the Al content and the Si content is It has been found that the electric resistance can be lowered by forming a base plate of a titanium alloy plate having a 0.2 to 1.0 mass% average particle diameter of 5 to 20 ⁇ m and forming an electrode catalyst layer thereon. This is the embodiment.
• the composition and the average particle size in this way, at least one of Al and Si is present in a certain amount in the oxide film formed on the surface, thereby suppressing the growth of the oxide film and oxidizing.
• the adhesion between the film and the electrode catalyst layer can be improved, and as a result, the electrical resistance can be lowered. Therefore, the total content of Al and Si contained in the oxide film is preferably 0.08 to 0.55% by mass.
• titanium alloy plate in this specification is a concept including an embodiment in which an oxide film is formed on the surface.
• the composition described below is basically the composition of the metal portion excluding the oxide film on the surface.
• the oxide film is formed in a short time even if it is removed as described above, it is often difficult to complete the composition analysis with the oxide film removed.
• the thickness of the oxide film formed on the surface is, for example, about 20 nm or less, and the amount of the oxide film is much smaller than the amount of the metal portion.
• composition analysis using the bulk sample in the state in which the oxide film was formed as a composition of a titanium alloy plate.
• a method generally used for composition analysis such as ICP emission spectroscopy may be used.
• a value calculated from the raw material composition and the amount used may be used.
• the titanium alloy plate for an electrode according to the embodiment of the present invention has Al: 0.1 to 1.0 mass% and Si: 0.1 to 1 Including at least one of 0.0 mass%.
• the total of Al and Si is 0.2 to 1.0% by mass. That is, when only Al is contained, the content of Al is 0.2% by mass or more in order to satisfy the lower limit of 0.2% by mass of the total of Al and Si. In order to satisfy the total lower limit of 0.2% by mass, the Si content is 0.2% by mass or more.
• the balance consists of Ti and inevitable impurities.
• the titanium alloy plate for electrodes is usually used after being processed into a shape having a large number of holes such as an expanded metal or a punched perforated plate, but it is difficult to process into these shapes.
• At least one of Al: 0.3 to 0.5% by mass and Si: 0.3 to 0.5% by mass is included, and the total of Al and Si is 0.6 to 0.9% by mass.
• the average crystal grain size of the titanium alloy substrate for electrodes according to the embodiment of the present invention is 5 ⁇ m or more and 20 ⁇ m or less.
• the adhesion between the surface oxide film and the electrode catalyst layer can be improved.
• One reason is that the surface roughness tends to decrease when the average crystal grain size is 20 ⁇ m or less.
• Si and Al tend to be concentrated at the grain boundaries. Further, when the oxide film is formed, Si and Al in the crystal grains do not enter the oxide film and tend to be ejected to the metal portion. On the other hand, Si and Al at the grain boundaries tend to be incorporated into the oxide film. For this reason, a sufficient amount of Si and / or Al is contained in the oxide film by reducing the average crystal grain size, increasing the grain boundaries, and concentrating more Si and Al at the grain boundaries. This can improve the adhesion between the oxide film and the electrode catalyst layer. Further, containing a sufficient amount of Si and / or Al in the oxide film also has an effect of suppressing the growth of the oxide film. As a result, the electrical resistance can be reduced and the electrolytic efficiency can be improved.
• the average crystal grain size exceeds 20 ⁇ m, the above-mentioned effect of improving adhesion cannot be obtained sufficiently.
• the average crystal grain size is less than 5 ⁇ m, the hardness increases and the workability decreases. That is, the titanium alloy plate for electrodes is usually used after being processed into a shape having a large number of holes such as an expanded metal or a punched perforated plate, but it is difficult to process into these shapes.
• the average crystal grain size is preferably 10 ⁇ m or more and 15 ⁇ m or less. The average crystal grain size can be determined by a section method using the result of optical microscope structure observation.
• the oxide film formed on the surface of the titanium alloy plate according to the embodiment of the present invention preferably contains at least one of Al and Si, and the total content of Al and Si is 0.08 to 0.55 mass%. is there. That is, when the oxide film contains Al and does not contain Si, the content of Al in the oxide film is preferably 0.08 to 0.55% by mass.
• the oxide film contains Si and does not contain Al
• the content of Si in the oxide film is preferably 0.08 to 0.55% by mass.
• the oxide film contains Al and Si, the total content of Al and Si in the oxide film is 0. It is preferably 0.08 to 0.55% by mass.
• the total content of Al and Si exceeds 0.55% by mass, the hardness of the oxide film increases, and wear of tools and the like is accelerated during processing into a shape having a large number of holes such as expanded metal or punched perforated plates.
• the total content of Al and Si is preferably 0.55% by mass or less.
• the oxide film contains at least one of Al and Si, and the total content of Al and Si is 0.10 to 0.40 mass%.
• the Al content and the Si content in the oxide film can be measured by performing composition analysis using EDS attached to the TEM during TEM observation.
• Method for Producing Titanium Alloy Plate for Electrode a method for producing a titanium alloy plate for an electrode according to an embodiment of the present invention will be described. Melting and forging as necessary to obtain a slab such as bloom or slab having the desired composition. For the melting, a method usually used for melting a titanium alloy such as VAR may be used. When obtaining a small amount of sample, it may be obtained by button arc melting or the like.
• the obtained slab such as bloom or slab is heated to 750 ° C. to 850 ° C. and then hot-rolled to obtain a rolled sheet.
• the heating may be performed in the atmosphere by a flame of a direct flame burner arranged above and below in the heating furnace.
• 3 to 5 mm can be exemplified as an example of the finished thickness of hot rolling.
• annealing is performed to remove processing strain.
• the plate material after annealing has an oxide scale and an oxygen diffusion layer on the surface by hot rolling and annealing heating. If these remain, the electrical resistance increases, and the electrolytic efficiency is lowered when used as an electrode. Moreover, it becomes a cause of wrinkles at the time of cold rolling. For this reason, it is necessary to remove the oxide scale and the oxygen diffusion layer. For example, it can be removed by pickling.
• the thickness (total thickness) L (m) of the oxide scale and the oxygen diffusion layer is determined by the heating temperature T (K) and the heating time t (seconds), and can be obtained by the following equation (1).
• L 2 (Dt) 0.5 (1)
• D D 0 ⁇ EXP ( ⁇ Q / (RT))
• diffusion coefficient D 0 5.08 ⁇ 10 ⁇ 7 m 2 / sec
• activation energy Q 140 kJ / mol
• gas constant R 8. 3144
• the removal amount (pickling amount) needs to exceed L.
• Pickling can be performed using hydrofluoric acid or the like.
• the rolled sheet is placed in the furnace and the annealing treatment is performed in the atmosphere in order to remove the processing strain.
• the heating temperature at this time 780 to 830 ° C.
• the average crystal grain size can be controlled within a predetermined range.
• the oxide scale and the oxygen diffusion layer are expressed by the equation (1) as in the hot rolling step. Thickness L is obtained, and the surface is removed by pickling or the like by an amount exceeding L obtained here. Pickling can be performed using hydrofluoric acid or the like.
• titanium is an active metal with oxygen
• an oxide film is formed on the surface of the titanium alloy plate immediately after pickling.
• Al and Si existing near the surface are taken into the oxide film. If pickling is insufficient and an oxygen diffusion layer is present near the surface, oxygen will interfere and Al and Si will not be easily taken into the oxide film, and the oxide film will contain a sufficient amount of Al and / or Si. Can not be made. For this reason, it is necessary to remove the surface by an amount (thickness) equal to or greater than L obtained by the formula (1) by pickling or the like.
• the titanium alloy plate for electrodes according to the embodiment of the present invention can be obtained.
• the specimens were produced as follows. An ingot of titanium alloy having a size of 40 mm in diameter and 20 mm in height and having each component composition shown in Table 1 was produced by button arc melting. This ingot was heated to 1000 ° C. and then forged to a thickness of 10 mm ⁇ width of 35 mm ⁇ length of 75 mm. After surface grinding, after heating at 850 ° C. for 120 minutes, hot rolling was performed to obtain a plate having a thickness of 3.5 mm ⁇ width of 35 mm ⁇ length of 165 mm. Thereafter, annealing was performed in the air at 750 ° C. for 20 minutes.
• the thickness L of the oxide scale and oxygen diffusion layer determined by the equation (1) was about 80 ⁇ m.
• the removal amount by pickling was set to 120 ⁇ m on one side (240 ⁇ m on both sides).
• cold rolling was performed at room temperature to obtain a plate having a thickness of 0.52 mm, a width of 36 mm, and a length of 1000 mm.
• this plate was annealed in the air at 800 ° C. for 2 minutes.
• pickling was performed with hydrofluoric acid to obtain a test material.
• the thickness L of the oxide scale and oxygen diffusion layer determined by the equation (1) was about 6 ⁇ m.
• the removal amount by pickling was set to 10 ⁇ m on one side (20 ⁇ m on both sides).
• test material was cut into a predetermined size, and a cross-sectional observation (magnification ⁇ 100,000) was performed with a transmission electron microscope (TEM), and the resulting structure photograph (TEM image) , Five portions where the thickness of the oxide film was considered to be representative were selected, the thickness of the oxide film of this portion was measured, and the average value was defined as the oxide film thickness. The results are shown in Table 1.
• the average crystal grain size was measured by a section method for one visual field having an area of 520 ⁇ m ⁇ 860 ⁇ m, using a structure observation result (magnification ⁇ 100) by an optical microscope. The results are shown in Table 1.
• Examples 1 to 7 and Comparative Example 1 have a hardness (Hv) of less than 200 and excellent workability.
• Comparative Example 2 with an excessive amount of Si and Comparative Example 3 with an excessive amount of Al have a hardness of 200 or more, and workability is insufficient.
• the sample was dried for 2 minutes, and the sample after the drying treatment was placed in an atmospheric heat treatment furnace having a furnace temperature of 475 ° C., held for 10 minutes, and then taken out. From the application of the catalyst layer forming solution to the heat treatment (holding), lamination was repeated 5 times, and finally, heat treatment was performed at 500 ° C. for 60 minutes to form an electrode catalyst layer.
• the contact resistance of the sample on which the electrode catalyst layer was formed was measured.
• the sample after forming the catalyst layer was sandwiched between gold plates, and the two gold plates sandwiched with the sample were sandwiched between two copper electrodes with a load of 10 kgf so that the contact area would be 1 cm 2 .
• a current was passed between the two copper electrodes, and the voltage at that time was measured with a voltmeter installed between the two gold plates.
• the contact resistance was obtained from the flowed current and the measured voltage.
• Table 1 shows the results.
• the contact resistance is 3.1 to 5.5 m ⁇ ⁇ cm 2 , which is a low value, and high electrolytic efficiency can be realized.
• Comparative Example 1 in which the amount of Si and Al is insufficient, and the average crystal grain size is excessive, the contact resistance is a large value of 6.5 m ⁇ ⁇ cm 2 .

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• 2016
  • 2016-08-24 JP JP2016163915A patent/JP6789035B2/ja active Active
• 2017
  • 2017-08-21 US US16/327,057 patent/US20190203322A1/en not_active Abandoned
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