JP2014189418A - Metal ion elution inhibitor and metal corrosion inhibition method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit metal corrosion by inhibiting ion elution from metal.SOLUTION: A metal ion elution inhibitor of the invention comprises an apatite compound. The apatite compound is selected from the group consisting of Ca10(PO4)6(OH)2,CaPO3(OH), Ca4(PO4)2O, Ca3(PO4)2 and Ca10(PO4)6F2. The apatite compound is contained in the amount of 0.1-30 pts.mass with respect to ready mixed-concrete 100 pts.mass.

Description

  The present invention relates to a metal ion elution inhibitor and a method for inhibiting corrosion of a metal using the same.

An apatite compound is a general term for phosphate minerals, and is divided into several types depending on the difference in chemical composition. In particular, hydroxyapatite (chemical formula Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ; hereinafter also referred to as HAP) is a main component of vertebrate teeth and bones, and is used for the treatment of dental caries and surgical medicine such as artificial bones. Etc. are used. Hydroxyapatite is also known to have a strong metal ion adsorption action.

  For example, Patent Document 1 describes that the erosion rate of a stent in a vascular environment can be adjusted by forming the stent using a metal matrix composite in which bioceramic particles are dispersed in a metal. Examples of the bioceramic particles include hydroxyapatite.

  However, in the stent described in Patent Document 1, the erosion rate of the metal matrix is adjusted by the degradation product of the bioceramic particles adjusting the local pH in the stent. Therefore, the invention described in Patent Document 1 does not utilize the characteristics of the bioceramic particles themselves (that is, non-decomposed products).

JP 2010-540092 A

  The present invention is based on the finding of the present inventors that the apatite compound itself has a metal ion elution suppressing action, and an object thereof is to inhibit metal corrosion.

According to the first aspect of the present invention, a metal ion elution inhibitor containing an apatite compound is provided.
According to the 2nd side surface of this invention, the concrete containing the said metal ion elution inhibitor is provided.
According to the 3rd side surface of this invention, resin containing the said metal ion elution inhibitor is provided.
According to the 4th side surface of this invention, the metal container which applied the said metal ion elution inhibitor to the internal surface and / or the external surface is provided.
According to a fifth aspect of the present invention, there is provided a method for inhibiting corrosion of a metal, comprising bringing the metal ion elution inhibitor into contact with a metal.

  The metal ion elution inhibitor of the present invention can inhibit metal corrosion.

The figure which shows the influence of HAP on the ion elution from metallic aluminum in silver nitrate aqueous solution. The figure which shows the influence of HAP on the electrochemical reaction of the battery produced using the metal aluminum plate and the metal silver plate. The photograph figure which shows the influence of HAP which acts on the ion elution from the iron nail in a sodium chloride solution. The figure which shows the influence of HAP on the ion elution from the iron nail in a sodium chloride solution. The figure which shows the influence of HAP which acts on the ion elution from the iron piece in a sodium chloride solution. The photograph figure which shows the reinforcement corrosion inhibitory effect of a HAP mixing reinforced concrete block. The photograph figure which shows the corrosion inhibitory effect with respect to the metal in a metal powder mixing concrete block. The figure which shows the influence of HAP which acts on the iron ion elution from an iron powder mixing concrete block. The photograph figure which shows the iron nail corrosion inhibitory effect of a HAP mixing | blending acrylic resin. The figure which shows the influence of the apatite compound on the ion elution from the iron nail in a sodium chloride solution. The figure which shows the influence of the apatite compound on the ion elution from metal aluminum in silver nitrate aqueous solution.

Hereinafter, the present invention will be described in detail.
The metal ion elution inhibitor of the present invention contains an apatite compound as an active ingredient. In addition, the solvent, excipient | filler, etc. which are normally used in the said field | area may be included. An apatite compound is a general term for phosphate minerals, and is classified into several types depending on the difference in chemical composition. Examples of the apatite compound include hydroxyapatite (Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ), CaPO ₃ (OH), Ca ₄ (PO ₄ ) ₂ O, Ca ₃ (PO ₄ ) ₂ , fluoroapatite (Ca ₁₀ (PO ₄ ) ₆ F ₂ ) and the like. In the present invention, any apatite compound can be used, but hydroxyapatite is more preferable. When animal-derived hydroxyapatite is used, its origin is not particularly limited, and for example, hydroxyapatite derived from porcine bone, fish bone, bird or reptile bone can be used. By contacting the metal ion elution inhibitor of the present invention containing the apatite compound as described above with a metal, corrosion of the metal can be inhibited.

  Hydroxyapatite is known to have a metal ion adsorption action. However, the present inventors have newly found that the apatite compound has an action of suppressing the release of electrons from the metal. That is, the metal corrosion inhibition action of the present invention is independent of the metal ion adsorption action of hydroxyapatite, and is a result of the apatite compound suppressing electron release from the metal, that is, metal ion elution.

  Metal corrosion can be expressed as the following reaction formula (1). The metal ion elution inhibitor of the present invention suppresses elution of metal ions by suppressing the release of electrons from the metal in the anode reaction of the following reaction formula (1). In the following reaction formula (1), M means a metal.

[Reaction (1)]
M → M ⁺ + e ⁻ (Anode reaction)
O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻ (cathode reaction)
The metal ion elution inhibitor of the present invention is effective when brought into contact with a metal. Specifically, the metal ion elution inhibitor can be mixed with a predetermined substance, and the resulting mixture can be brought into contact with the metal, or the metal ion elution inhibitor can be directly mixed with the metal. Examples of the target metal include, but are not limited to, iron, aluminum, copper, lead, zinc, nickel, chromium, manganese, titanium, and alloys thereof.

  Examples of the substance to be mixed with the metal ion elution inhibitor include concrete, resin, clay, diatomaceous earth, sand, silica powder and the like. Moreover, in one aspect | mode, the metal ion elution inhibitor of this invention can be applied to the internal surface and / or external surface of metal containers.

  When the concrete containing the metal ion elution inhibitor of the present invention is used as reinforced concrete, corrosion of the reinforcing steel over time can be suppressed. At this time, the apatite compound is preferably contained in an amount of 0.1 parts by mass or more, more preferably in an amount of 0.1 to 30 parts by mass, and still more preferably 0 with respect to 100 parts by mass of ready-mixed concrete. It is contained in an amount of 5 to 30 parts by mass, particularly preferably 1 to 10 parts by mass. When the blending amount of the apatite compound is the above amount, sufficient concrete strength can be ensured.

  Here, ready-mixed concrete means a mixture of concrete materials before solidification. Concrete materials include, for example, cement, water, admixtures, and the like, and are blended according to the target strength, durability, workability, and the like. The composition of concrete in which the metal ion elution inhibitor of the present invention can be used is not particularly limited. For example, it can be used for general strength concrete, high strength concrete that obtains high strength by reducing water. is there.

  If the metal ion elution inhibitor of this invention is mix | blended with resin and it uses as a metal coating resin, corrosion of a metal can be inhibited as a result of suppressing the metal ion elution on the metal surface. For example, if a metal coating resin containing the metal ion elution inhibitor of the present invention is coated on the surface of a water pipe or the like, the durability of the water pipe where corrosion after embedding is a major problem can be greatly improved. . At this time, the apatite compound is preferably contained in an amount of 0.1 parts by mass or more, more preferably in an amount of 0.1 to 90 parts by mass, and still more preferably 0.8. It is contained in an amount of 1 to 50 parts by weight, particularly preferably 0.5 to 30 parts by weight, and most preferably 1 to 10 parts by weight. By setting it as such a compounding quantity, a favorable rust prevention effect, uniform dispersibility, and coating viscosity can be given. Although resin which can mix | blend the metal ion elution inhibitor of this invention is not specifically limited, For example, an acrylic resin, a silicone resin, a urethane resin, an oil-based paint etc. are mentioned.

  The metal container in which the metal ion elution inhibitor of the present invention is applied to the inner surface and / or the outer surface is for storing, for example, spent nuclear fuel in nuclear power generation or fuel melted down or melted through due to an accident for a long period of time. Available to: These nuclear wastes must be stored in water for a long period of time. However, when salt is attached to the nuclear waste, the salt is dissolved in the water to be stored and becomes an electrolyte solution. Therefore, when it is stored in a normal metal container, corrosion surely occurs over a long period of time. In contrast, by using a metal container in which the metal ion elution inhibitor of the present invention is applied to the inner surface and / or the outer surface, even when the electrolyte solution is generated as described above, it can be used for a long time. Can inhibit the corrosion of the container.

  The metal ion elution inhibitor of the present invention can be used for various metals for the purpose of inhibiting corrosion, and its use is considered to be various other than those described above.

  According to another embodiment of the present invention, there is provided a method for inhibiting corrosion of a metal comprising contacting the metal ion elution inhibitor of the present invention with a metal. The term “contact” as used herein includes not only mixing the metal ion elution inhibitor with a predetermined substance and bringing the resulting mixture into contact with the metal, but also mixing the metal ion elution inhibitor directly with the metal. Shall be included. Contact can be carried out under neutral conditions. Neutral conditions preferably mean conditions of pH 6-8, more preferably conditions of pH 6-7. Since the metal ion elution inhibitor of the present invention utilizes the metal ion suppression action by the non-decomposed product of the apatite compound, it can exhibit a metal corrosion inhibitory action even under neutral conditions.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, the content of this invention is not limited by this.

Test Example 1: Confirmation of Mechanism of Metal Ion Elution Suppression by Hydroxyapatite This experiment consists of metal ion elution suppression action (ie, metal corrosion inhibition action) by hydroxyapatite (hereinafter also referred to as HAP) and metal ion adsorption of HAP. This was done to confirm that the effect was unrelated.

  In order to examine the inhibitory action of HAP on the elution of ions from metals by electrochemical reaction, the influence of HAP on the elution of aluminum ions from aluminum and the precipitation of metallic silver in an aqueous silver nitrate solution was examined. As HAP, one derived from porcine bone was used. When an aluminum reaction is performed in an aqueous silver nitrate solution, aluminum having a relatively high ionization tendency is ionized, and silver ions having a relatively low ionization tendency are precipitated as metallic silver. The reason for using silver and aluminum in this experiment is that neither silver ions nor aluminum ions are easily adsorbed to HAP. In particular, when 1% HAP is blended, none of the ions are adsorbed at all.

Hereinafter, the test contents will be specifically described.
Reaction systems 1 to 8 shown below were prepared and stirred for 7 days. The amount of the silver nitrate aqueous solution was 100 mL so that the silver ion concentration was 3000 mg / L. As metal aluminum, 300 mg of aluminum pieces were used. The aluminum ion concentration of the reaction systems 1 to 8 after 7 days was measured with an ICP emission analyzer (manufactured by Shimadzu Corporation).

  Reaction systems 1 to 8 are as follows. In the reaction systems 3, 4 and 8, “1% HAP” means that 1 g of HAP was added to 100 mL of purified water or silver nitrate aqueous solution. In addition, “0.1% HAP” in reaction system 6 and “0.3% HAP” in reaction system 7 mean that 0.1 g and 0.3 g of HAP were added to 100 mL of an aqueous silver nitrate solution, respectively. means.

Reaction system 1: metal aluminum + purified water (100 mL)
Reaction system 2: Silver nitrate aqueous solution Reaction system 3: Metal aluminum + 1% HAP + Purified water (100 mL)
Reaction system 4: Silver nitrate aqueous solution + 1% HAP
Reaction system 5: Metallic aluminum + silver nitrate aqueous solution Reaction system 6: Metallic aluminum + silver nitrate aqueous solution + 0.1% HAP
Reaction system 7: Metallic aluminum + silver nitrate aqueous solution + 0.3% HAP
Reaction system 8: Metallic aluminum + silver nitrate aqueous solution + 1% HAP
The result of the aluminum ion elution from the metal aluminum in the said reaction systems 1-8 is shown in FIG. In the case where HAP was not added (reaction system 5), metallic silver was deposited on the aluminum surface immersed in the aqueous silver nitrate solution, and at the same time, the aluminum ion concentration in the solution was significantly increased. This is a result of reaction (2) shown below.

[Reaction (2)]
Al → Al ³⁺ + 3e ⁻ (Anode reaction)
Ag ⁺ + e ⁻ → Ag (cathode reaction)
On the other hand, when 0.1%, 0.3% and 1% HAP were added (reaction systems 6 to 8), the precipitation of metallic silver on the aluminum surface and the increase in the aluminum ion concentration in the solution were: Almost completely suppressed. This is probably because HAP suppressed the release of electrons from the metal aluminum in the initial stage of the anode reaction.

  From the above results, the metal corrosion inhibitory action by HAP of the present invention has nothing to do with the metal ion adsorption action of HAP, and is derived from suppressing ion elution from metal. Proven. This is a new function of HAP that has not been reported worldwide.

  In order to further confirm the action of HAP to suppress metal ion elution, an electrochemical reaction was performed using an electrolytic solution containing metallic aluminum and metallic silver, and the influence of HAP was examined. A 10% sodium chloride aqueous solution (pH 7) was used as the electrolytic solution, and a battery was fabricated using a metal aluminum plate and a metal silver plate as electrodes. Thereafter, changes in voltage were examined when HAP was not added to the electrolyte and when 1% HAP was added. The HAP concentration is 1% (HAP 1 g with respect to 100 mL of the electrolyte).

  As a result, as shown in FIG. 2, in a battery made of a metal aluminum plate and a metal silver plate, a voltage of about 1.6 mV was confirmed when HAP was not added. On the other hand, when 1% HAP was added, the voltage dropped to about 0.3 mV. This result shows that HAP suppresses the movement of electrons between the metal aluminum plate and the metal silver plate, and supports the suppressive action of HAP against the release of electrons from the metal. This voltage drop due to HAP was also confirmed in a battery made of a metal aluminum plate and a metal platinum plate.

Example 1: Metal Iron Corrosion Inhibition Action by HAP Example 1-1: Inhibition of Iron Ion Elution and Iron Nail Corrosion Inhibition by HAP The inhibitory action of porcine bone-derived HAP on iron nail corrosion in 2% sodium chloride solution was examined. . 0 g (0% HAP), 1 g (1% HAP), 3 g (3% HAP) or 10 g (10% HAP) of HAP was added to 100 mL of 2% aqueous sodium chloride solution (pH 7), respectively, and then pH 6. Adjusted to 5. An iron nail was put into the prepared liquid and left for 3 months. As a result, changes as shown in FIGS. 3A to 3D were observed after 2 days from the standing. FIG. 4 shows the relationship between the HAP concentration and the iron ion elution amount after 2 days from standing.

  As shown in FIG. 3A, when no HAP was added, generation of reddish brown iron rust (iron oxide) was observed after two days due to corrosion of the iron nail. In this case, as shown in FIG. 4, elution of 5.5 mg / L of iron ions was confirmed. On the other hand, in the solution containing 1%, 3% and 10% of HAP, as shown in FIGS. 3B to 3D, almost no iron rust was observed. Moreover, the iron ion concentration in 2% sodium chloride aqueous solution was also less than 0.3 mg / L, 0.1 mg / L, and 0.1 mg / L, respectively (FIG. 4).

  Furthermore, even after 3 months, the dissolved iron ion concentration in the solution to which HAP was not added was 5.8 mg / L, but in the solution containing 3% HAP, 1.5 mg / L, In the solution to which 10% HAP was added, it was less than 0.1 mg / L. As a result of measuring the weight of the iron nail after 3 months, when no HAP was added, the average weight of the iron nail was clearly reduced from 3.03 g to 2.86 g, but depending on the concentration of HAP, The decrease in nail weight was significantly suppressed. In particular, when 10% HAP was added, the iron nail weight did not change at all.

As a result, it was confirmed that the corrosion of metallic iron can be almost completely suppressed by 3 to 10% HAP.

Example 1-2: Suppression of iron ion elution and iron piece corrosion inhibition by HAP After adding HAP into 100 mL of 3.5% sodium chloride aqueous solution (pH 7), a metal iron piece (length 15 mm × width 15 mm × width 1.5 mm) was added. In addition, the mixture was stirred for 7 days. The amount of HAP added was 0 g (0% HAP), 1 g (1% HAP), 3 g (3% HAP), 5 g (5% HAP) or 10 g (10% HAP). The eluted iron ion concentration in the sample solution was measured daily using an ICP emission spectrometer (manufactured by Shimadzu Corporation). The daily variation in elution of iron ions from the metal iron piece is shown in FIG. When no HAP was added, generation of reddish brown iron rust (iron oxide) due to corrosion of the iron nail was observed after one day, and further elution of iron ions over time was confirmed. On the other hand, when HAP was added, elution of iron ions from the metal iron piece was remarkably suppressed depending on the HAP concentration.

  As a result of comparing the weights of the metal iron pieces after 7 days, the weight of the iron pieces decreased with the elution of iron ions from the iron pieces when HAP was not added. On the other hand, when HAP was added, the decrease in iron piece weight was suppressed depending on the HAP concentration. The iron piece weight without HAP decreased from 2.56 g to 2.47 g after 7 days, but when 1% HAP was added, 2.58 g to 2.55 g, 3% HAP. From 2.53 g to 2.51 g when 5% HAP is added, 2.67 g to 2.67 g when 5% HAP is added, and from 2.64 g to 2.64 g when 10% HAP is added Stayed in. This shows that the elution of iron ions from metallic iron was strongly suppressed by HAP. From these results, it was confirmed that the addition of 3% to 10% HAP almost completely suppressed the elution of iron ions from metallic iron.

Example 2: HAP-blended concrete block Example 2-1: Preparation of HAP-blended concrete block and compressive strength test A HAP-blended concrete block was fabricated as follows.

First, water, cement, an admixture (a naphthalenesulfonic acid-based high-performance water reducing agent), blast furnace slag, and porcine bone-derived HAP were mixed with a mixer for kneading (fresh concrete) and then put into a cylindrical formwork. It was solidified by vibration compaction molding with a vibration compactor for about 1 minute, followed by curing (standing). The blending amount of HAP was 1 part by mass (1% HAP), 3 parts by mass (3% HAP), or 10 parts by mass (10% HAP) with respect to 100 parts by mass of ready-mixed concrete. The amount of each material in the case of 10% HAP blend, cement 243kg / ^{m 3,} water 108 kg / ^{m 3,} slag 1060kg / ^{m 3,} and the admixtures ^{1.22kg / m 3, HAP157kg / m} 3.

As a result of measuring the compressive strength of the concrete block produced as described above according to JIS A1108, even when 1%, 3%, and 10% HAP are blended, the design standard strength of building concrete is 21 N / mm. A compressive strength of ² or more was secured. No significant difference was confirmed compared with the compressive strength of the concrete block not containing HAP. As a result of the above, it was confirmed that there is no problem in blending HAP with concrete in the concrete design standard for building.

Example 2-2: Reinforcement corrosion inhibitory action by HAP-mixed concrete block 1 part by mass (1% HAP), 3 parts by mass (3% HAP) or 10 parts by mass of HAP (derived from porcine bone) with respect to 100 parts by mass of ready-mixed concrete A reinforced concrete block containing 10 parts by mass (10% HAP) was produced in the same manner as in Example 2-1, and immersed in a 2% aqueous sodium chloride solution (pH 7) and allowed to stand. Thereafter, the corrosion situation of the reinforcing bars was observed for 8 months, but no corrosion of the reinforcing bars was observed even in the reinforced concrete not containing HAP. The reason is considered that the sodium chloride solution did not penetrate into the concrete, and that the strong basicity of the calcium hydroxide as a concrete component did not change in a short period of several months. From the mechanism of metal iron corrosion, it is considered that metal iron corrosion does not occur under strong basic conditions.

  Therefore, a rebar corrosion test was carried out using a strongly acidic 1N hydrochloric acid-containing 5% sodium chloride solution instead of the 2% sodium chloride aqueous solution. Furthermore, in this experiment, a reinforced concrete porous block made of porous concrete blended with steel slag was used instead of a normal reinforced concrete block into which the solution did not penetrate. The pore diameter of this reinforced concrete porous block is 5 to 10 mm, and the porosity is 20%.

  The state after 8 months is shown in FIGS. As shown to Fig.6 (a), the iron oxide (red rust) was confirmed by the horizontal part (grounding surface with the reaction tank bottom part) of the reinforced concrete porous block which is not mix | blended with HAP. However, even in this reinforced concrete porous block, the rebar embedded inside was not corroded at all. Further, the 5% sodium chloride solution containing 1N hydrochloric acid did not penetrate at all to the reinforcing bars in the center of the block. Furthermore, as shown in FIG. 6 (b), iron oxide (red rust) was confirmed even in a concrete porous block without reinforcing bars, and therefore iron in steel slag existing near the concrete porous block surface. Alternatively, it is considered that the iron sand in the aggregate was corroded and remained as iron oxide (red rust) on the side of the concrete porous block. On the other hand, when HAP was blended in the concrete porous block, generation of iron oxide (red rust) at the side of the concrete porous block could be suppressed. In particular, when 3% and 10% HAP were blended, as shown in FIGS. 6 (d) and (e), generation of iron oxide (red rust) in the lateral part of the concrete porous block was almost suppressed. These results show that the corrosion of metallic iron in the concrete can be more strongly suppressed by adding 3% or more of HAP to the concrete.

Example 2-3: Ion elution inhibitory action and corrosion inhibitory action on metal in metal powder-mixed concrete block by HAP The commercially available instant concrete purchased from Matsumoto Sangyo Co., Ltd. was used as the concrete material. To 100 parts by mass of concrete, iron sand (5 parts by mass), HAP 1 part by mass (1% HAP), 3 parts by mass (3% HAP) or 10 parts by mass (10% HAP) are uniformly mixed, 20 cm × 13 cm A 3 cm concrete block was produced. These concrete blocks were left still in 1.2 L of 10% sodium chloride solution containing 1N hydrochloric acid. Using an ICP emission analyzer (manufactured by Shimadzu Corporation), the ion concentrations in the solution after standing for 30 days were compared.

  The state of each concrete block after 30 days of standing is shown in FIG. In the concrete block not containing HAP (FIG. 7A), red rust (iron oxide) was generated on the concrete surface, and discoloration due to rust was confirmed even in the solution that was allowed to stand. On the other hand, as shown in FIGS. 7B to 7D, when 1%, 3%, or 10% of HAP was blended, no red rust occurred.

  Moreover, the iron ion density | concentration eluted from each concrete block 30 days after stationary is shown in FIG. In FIG. 8, when reaction system 1 does not contain HAP, reaction system 2 contains 1% HAP, reaction system 3 contains 3% HAP, reaction system 4 contains 10% HAP. Is the case. In the concrete block not mixed with HAP (reaction system 1), a high iron ion concentration was confirmed, and apparent iron ion elution from sand iron in the concrete was confirmed. On the other hand, in concrete blocks containing 1%, 3% or 10% of HAP, elution of iron ions was suppressed depending on the HAP concentration.

Example 3: HAP-blended resin A HAP-blended acrylic resin was produced by blending 10 parts by mass of porcine-derived HAP (referred to as 10% HAP) with 100 parts by mass of acrylic resin. Specifically, a solid powder of HAP was blended in an acrylic resin with uniform stirring. The HAP-containing acrylic resin thus obtained was coated on the iron nail surface. As a comparative example, an acrylic resin not containing HAP was coated on the iron nail surface. These were placed in a 10% sodium chloride aqueous solution (pH 7), and the corrosion state of the iron nail was observed for one month. As a result, changes shown in FIGS. 9A to 9C were observed.

  As shown in FIG. 9 (a), the occurrence of red rust was confirmed when HAP was not blended. However, when HAP was blended, as shown in FIG. 9 (b), the occurrence of red rust was completely absent. Not observed. Moreover, as shown in FIG.9 (c), when only an iron nail was put into the sodium chloride aqueous solution, the intense red rust generate | occur | produced. This result shows that corrosion of the metal iron surface can be suppressed by applying and coating the HAP compound resin on the metal iron surface.

In the above examples, hydroxyapatite (Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ) was used, but CaPO ₃ (OH), Ca ₄ (PO ₄ ) ₂ O, Ca ₃ (PO ₄ ) ₂ , Ca ₁₀ ( Similarly, when other apatite compounds such as PO ₄ ) ₆ F ₂ were used, the iron ion elution suppression action and the corrosion inhibition action from metallic iron could be confirmed. Therefore, the apatite compound other than hydroxyapatite can also be used as a rust inhibitor. An example is shown below.

Example 4: Inhibition of metal ion elution by an apatite compound Example 4-1: Inhibition of iron ion elution by an apatite compound The inhibitory action of an apatite compound on iron nail corrosion in a 2% sodium chloride solution was examined. 1 g (1% apatite compound) of each apatite compound was added to 100 mL of 2% aqueous sodium chloride solution (pH 7), and then adjusted to pH 6.5 with hydrochloric acid. An iron nail was put into the prepared liquid and left for 2 days. The iron ion concentration of the reaction systems 1 to 8 after 2 days was measured with an ICP emission spectrometer (manufactured by Shimadzu Corporation). FIG. 10 shows the iron ion concentration eluted in the solution containing each apatite compound. The reaction system is shown below.

Reaction system 1: Iron nail + sodium chloride solution Reaction system 2: Iron nail + sodium chloride solution + 1% HAP (hexagonal crystal; since pig bone)
Reaction system 3: Iron nail + sodium chloride solution + 1% Ca ₄ (PO ₄ ) ₂ O
Reaction system 4: Iron nail + sodium chloride solution + 1% Ca ₃ (PO ₄ ) ₂
Reaction system 5: iron nail + sodium chloride solution + 1% CaPO ₃ (OH)
Reaction system 6: iron nail + sodium chloride solution + 1% Ca ₁₀ (PO ₄ ) ₆ F ₂
Reaction system 7: Iron nail + sodium chloride solution + 1% HAP (monoclinic)
Reaction system 8: Iron nail + sodium chloride solution + 1% HAP (hexagonal crystal; since fish bone)
As shown in FIG. 10, in the reaction system 1, elution of 5.7 mg / L of iron ions was confirmed. On the other hand, the iron ion elution suppression action was recognized in all reaction systems except the reaction system 1.

Example 4-2: Inhibition of Aluminum Ion Elution by Apatite Compound Reaction systems 1 to 10 shown below were prepared and stirred for 7 days. The amount of the silver nitrate aqueous solution was 100 mL so that the silver ion concentration was 3000 mg / L. As metal aluminum, 300 mg of aluminum pieces were used. The aluminum ion concentration of the reaction systems 1 to 10 after 7 days was measured with an ICP emission analyzer (manufactured by Shimadzu Corporation).

  Reaction systems 1 to 8 are as follows. “1%” in all reaction systems means that 1 g of apatite compound was added to 100 mL of an aqueous silver nitrate solution.

Reaction system 1: metal aluminum + purified water (100 mL)
Reaction system 2: Silver nitrate aqueous solution Reaction system 3: Metal aluminum + silver nitrate aqueous solution Reaction system 4: Metal aluminum + silver nitrate aqueous solution + 1% HAP (hexagonal crystal since pig bone)
Reaction system 5: Metallic aluminum + silver nitrate aqueous solution + 1% Ca ₄ (PO ₄ ) ₂ O
Reaction system 6: Metallic aluminum + silver nitrate aqueous solution + 1% Ca ₃ (PO ₄ ) ₂
Reaction system 7: Metallic aluminum + silver nitrate aqueous solution + 1% CaPO ₃ (OH)
Reaction system 8: Metallic aluminum + silver nitrate aqueous solution + 1% Ca ₁₀ (PO ₄ ) ₆ F ₂
Reaction system 9: Metallic aluminum + silver nitrate aqueous solution + 1% HAP (monoclinic)
Reaction system 10: Metallic aluminum + silver nitrate aqueous solution + 1% HAP (hexagonal crystal; since fish bone)
About the said reaction systems 1-10, the result of the aluminum ion elution from metal aluminum is shown in FIG. As shown in FIG. 11, for all the apatite compounds studied, an inhibitory action against aluminum ion elution from metallic aluminum in an aqueous silver nitrate solution was observed.

  According to the said embodiment and Example, the metal ion elution inhibitor containing an apatite compound can be provided. Moreover, according to the said embodiment and Example, it can be understood that this invention discovers the metal ion elution suppression effect of an apatite compound, and utilizes it. This metal ion elution suppression action is independent of the metal ion adsorption action of hydroxyapatite.

Claims (11)

  Metal ion elution inhibitor containing an apatite compound. The apatite compound is composed of Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ , CaPO ₃ (OH), Ca ₄ (PO ₄ ) ₂ O, Ca ₃ (PO ₄ ) ₂ and Ca ₁₀ (PO ₄ ) ₆ F _2. The metal ion elution inhibitor of Claim 1 selected from the group which consists of.   Concrete containing the metal ion elution inhibitor according to claim 1 or 2.   The concrete according to claim 3, wherein the apatite compound is contained in an amount of 0.1 to 30 parts by mass with respect to 100 parts by mass of ready-mixed concrete.   Resin containing the metal ion elution inhibitor of Claim 1 or 2.   The resin according to claim 5, wherein the apatite compound is contained in an amount of 0.1 to 90 parts by mass with respect to 100 parts by mass of the resin.   A clay containing the metal ion elution inhibitor according to claim 1 or 2.   A metal container in which the metal ion elution inhibitor according to claim 1 or 2 is applied to an inner surface and / or an outer surface.   A method for inhibiting corrosion of a metal, comprising bringing the metal ion elution inhibitor according to claim 1 or 2 into contact with a metal.   The method for inhibiting corrosion of a metal according to claim 9, wherein the contact is performed under neutral conditions.   The method for inhibiting corrosion of a metal according to claim 10, wherein the neutral condition is a condition of pH 6-8.

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