JP5201707B2 - A method for producing a photocathode anticorrosion coating structure. - Google Patents

Description

The present invention relates to a method for producing a full-time photocathode anticorrosion coating structure in which a layer made of a photocatalyst exhibiting a photocathode anticorrosive action and an electron storage material exhibiting a charge / discharge action is formed on the surface of a metal substrate.

This kind of full-time photocathode anticorrosion structure is conventionally known as shown in Patent Documents 1 to 3, and various attempts have been made.
Among these, the structure shown in FIG. 2C of Patent Document 3 shows a layer of a sintered body of a mixture of a powder made of a photoexcited semiconductor and a powder made of an electrochromic material.
However, since this is a layer of a sintered body of these powders, a sintering step is required, and there is a drawback that it is impossible to work on the installation site of the object.
In addition, the sintering of the mixture may cause a chemical reaction between the powders, and it is difficult to predict whether or not a desired effect can be exhibited after sintering.
If possible, strict control based on considerable experimentation should be performed during sintering, but there is no mention in the literature of such a thing.
For these reasons, the description merely describes an ideal that cannot be realized, and does not fall within the scope of fantasy and does not fall under the technical concept.
JP-A-11-71684 JP2003-96581A JP 2002-69677 A

In view of such circumstances, an object of the present invention is to provide an ideal method for producing a photocathode anticorrosion coating structure.

The present invention relates to a method for producing a full-time photocathode anticorrosion coating structure in which a layer made of a photocatalyst having a photocathode anticorrosive action and an electron storage material having a charge / discharge action is provided on the surface of a metal substrate, There the crystals of the photocatalyst ranging 7Nm～1myuemu, and particle size of the electron storage material in the range of 10nm~1μm crystals, solidified by mixing the sizing agent, and a set particles having a particle diameter 25～90Myuemu, this The aggregated particles are heated to a temperature of 4 × 10 ^{2 to} 25 × 10 ² ° C. and sprayed onto the surface of the metal substrate at supersonic speed, and the aggregated particles are crushed and dispersed by impact on the surface of the substrate, and each crystal Is attached to the surface of the substrate.

More present invention, by a photocatalyst and an electron storing material is both mixed as nanoparticles, transfer to electronic storage material from the photocatalyst is almost made in non-resistance state, Ru can very efficient charging.
Moreover, since these maintain the crystal body, mutual reaction is hard to occur, and a stable action can be exhibited over a long period of time.
Further, since the blown by warm spray method, it is possible to form the desired structure on the object surface to be treated, does not require other processing at the site where the article to be treated is used, the optical cathodic protection coating structure Ru can make.

FIG. 1 is an outline of a worm spray gun used in the practice of the present invention, and has a fuel supply port (2) and an oxygen supply port (3) for press-fitting fuel and oxygen into a combustion chamber (1). A port (5) for supplying an inert gas to the combustion chamber (1) is provided near the nozzle (4) which is the outlet of the combustion chamber (1). In this way, the supply amount of the oxygen and fuel is increased and decreased in inverse proportion to the increase and decrease of the press-fitting of the inert gas, and the temperature is adjusted while keeping the gas ejection speed from the nozzle (4) from fluctuating much. It can be adjusted in the range of 4 × 10 ^{2 to} 25 × 10 ² ° C.

Further, the aggregate particle diameter is not limited to the following examples, and can be up to 100 μm.
As the particle size increases, it becomes difficult to create aggregate particles. Further, unevenness is likely to occur in the sprayed layer.
The paste is not limited to PVA, and conventionally known pastes such as acrylic, polyester, and polyurethane can be used. It is also possible to use natural or semi-synthetic glues made of starch.

The crystal that functions as a photocatalyst is not limited to titanium oxide shown in the following examples, and zinc oxide, tungsten oxide, iron oxide, strontium titanate, cadmium sulfide, and the like can be used.
Further, the crystal grain size is not limited to those shown in Table 1 below, and those having a crystal grain size of 7 nm to 1 μm or less are preferable.
In addition, when it becomes a big thing exceeding 1 micrometer, there exists a possibility that catalyst activity may fall remarkably.
FIG. 2 is a graph showing the relationship between the particle size and the power generation capacity.
A current (Current) at an arbitrary potential (for example, 500 mV) indirectly indicates an anode current corresponding to the photocathode protection current. That is, the larger this current, the greater the possibility of taking a larger photocathode current.
Compared to the coating produced using TiO ₂ having a particle size of <1 μm by the conventional method (HVOF), the current value is large even when the Warm Spray is used, that is, the photocathodic anticorrosion performance is improved. Furthermore, when the particle size is <100 nm in WarmSpray, it can be seen that the photocathode anticorrosion current is further increased by almost 10 times.

The crystals used as the electron storage material are not limited to iron oxide, but are transition metal oxides that can exist stably in a plurality of valence states, such as vanadium oxide, chromium oxide, manganese oxide, and cobalt oxide. In addition, any substance that can incorporate protons (H +) together can be used.
Further, the crystal grain size is not limited to those shown in Table 1 below, and those having a grain size of 10 nm to 1 μm can be used.
In addition, when it becomes a big thing exceeding 1 micrometer, since an electron storage reaction also depends on a surface area, there exists a possibility that an electron storage capability may fall remarkably.
FIG. 3 is a graph showing charge / discharge characteristics of an electron storage material (Fe ₂ O ₃ ) in a full-time photocathode anticorrosion coating.
A peak in the negative direction of the current (Current) indicates the charging action, and the larger the peak height, the larger the charging capacity. A positive direction indicates a discharge action. The peak height corresponds to the discharge capacity. Compared to the coating prepared using Fe ₂ O ₃ having a particle diameter of <1 μm by the conventional method (HVOF), the peak is large even when using the Warm Spray, that is, the charge / discharge capacity is increased. Furthermore, when the particle diameter is <100 nm in WarmSpray, it can be seen that the charge / discharge capacity is more than doubled.

As shown in Table 1 below, aggregated particles having a diameter of 25 to 90 μm were prepared by mixing titanium oxide crystals for photocatalyst and iron oxide crystals as an electron storage material. (Figs. 4 and 5)
PVA was used as a paste to solidify the aggregated particles. Aggregated particles are obtained by mixing a paste with 2% by mass of a crystal mixture and granulating it by a spray drying method.
The aggregated particles thus granulated were sprayed and adhered to the base material under the conditions shown in Table 1 below using a warm spray gun.
The aggregated particles were crushed simultaneously with the adhesion, and the formed layer was almost uniform and both crystals were present. (Figs. 6 and 7)
In Table 1 below, the meanings of ○ and ◎ in results 1) and 2) are as follows.
1) A: High photocatalytic activity 1) ○: Photocatalytic activity 2) A: High electron storage activity 2) ○: Electron storage activity

  Since it is important not only to prevent corrosion of steel structures such as steel bridges but also to control the atmosphere in the container, a normal sacrificial corrosion protection system cannot be adopted. On the other hand, highly corrosion-resistant materials such as stainless steel can be effectively used for anticorrosion of radioactive substance storage containers in nuclear power generation facilities and the like that have the risk of stochastic local corrosion.

Longitudinal front view showing an outline of the structure of a gun for worm spray Graph showing the photocurrent characteristic of the photocatalyst (TiO ₂₎ in the full-time light cathodic protection coating. Graph showing the charge-discharge property of the electron storage material in the full-time light cathodic protection coating (Fe 2 _{O 3).} Micrograph of aggregated particles 4 is an enlarged cross-sectional view of the particle shown Enlarged side view of the coating layer Enlarged photo with part of Fig. 6 enlarged

Claims (1)

A method for producing a full-time photocathodic anticorrosive coating structure , wherein a layer comprising a photocatalyst having a photocathode anticorrosive action and an electron storage material having a charge / discharge action is provided on the surface of a metal substrate, having a particle size of 7 nm to 1 μm The above-mentioned photocatalyst crystals, the crystal grains of the electron storage material in the range of 10 nm to 1 μm, and the paste are mixed and solidified to form aggregate particles having a particle diameter of 25 to 90 μm. Heated to a temperature of × 10 ^{2 to} 25 × 10 ² ° C and sprayed onto the surface of the metal substrate at supersonic speed, the aggregated particles were crushed and dispersed by impact on the substrate surface, and each crystal was A method for producing a photocathode anticorrosive coating structure , characterized by being attached to a surface .