JP2547020B2 - High corrosion resistance amorphous nickel alloy - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a high corrosion resistant amorphous nickel alloy suitable as a corrosion resistant material in a severe corrosive environment such as high temperature concentrated phosphoric acid.

Conventional technology Currently, as a structural material for high temperature concentrated phosphoric acid plant, 30
9, 310, 446Mo stainless steel chrome molybdenum titanium steel, Hastelloy C, etc. are used, but none of them have sufficient corrosion resistance under the severe corrosion resistance environment such as high temperature concentrated phosphoric acid.

Normally, alloys are crystallized in the solid state, but applying a method that does not form long-period regularity in the atomic arrangement in the process of solid formation, such as limiting the alloy composition and rapidly quenching and solidifying from the molten state, , And an amorphous structure similar to a liquid is obtained. Such an alloy is called an amorphous alloy.

Amorphous alloys are mostly homogeneous single-phase alloys of supersaturated solid solutions, have significantly higher strength than conventional practical alloys, and exhibit various properties, such as abnormally high corrosion resistance, depending on the composition. The present inventors have conducted research utilizing the properties of such an amorphous alloy, and found that pitting corrosion occurs even in an aqueous solution containing a strong acid or a high concentration of chloride ions.
We have found a highly corrosion-resistant amorphous nickel alloy that does not undergo crevice corrosion and general corrosion, and filed as Japanese Patent Application No. 51-132290, which was previously explained. Found a highly corrosion-resistant amorphous alloy and applied for a patent as Japanese Patent Application No. 60-51036.Furthermore, found a highly corrosion-resistant amorphous alloy that can be used in a severe corrosive environment such as boiling concentrated nitric acid.
Patent applications were filed as 172860 and Japanese Patent Application No. 60-172861. All of these are amorphous nickel alloys. Since concentrated phosphoric acid has a high boiling point as described above, it is particularly corrosive at high temperatures, and corrosiveness cannot be obtained unless the alloy itself has the ability to form a stable protective film.

As a result of further research while studying various characteristics of amorphous alloys, the inventors of the present invention have disclosed the above-mentioned Japanese Patent Application No. 51-132290.
No. 60-51036, Reference 1 JP-A-62-33735 and 60-
Among the alloys described in No. 172861, particularly by adding an element that further enhances the protective film forming ability to an alloy having a high protective film forming ability or a similar alloy, oxidative power such as high temperature concentrated phosphoric acid is poor and severe corrosiveness It was found that an amorphous nickel alloy having a high corrosion resistance can be obtained by forming a stable protective film even in an acid, and previously filed Japanese Patent Application Nos. 61-225435 and 61-225436.

Problems to be Solved by the Invention Since concentrated phosphoric acid has a high boiling point, it is particularly corrosive at high temperatures, and no ordinary commercially available metallic material can be safely used. Even in such an environment, the alloys described in Japanese Patent Application No. 61-225435 and Japanese Patent Application No. 61-225436 exhibit corrosion resistance,
In such a corrosive environment where the use of ordinary metallic materials is extremely difficult, there is a demand for the development of various new metallic materials that can withstand use.

Means for Solving the Problems An object of the present invention is to provide an alloy which is non-oxidizing such as high temperature concentrated phosphoric acid, which hardly immobilizes metals, and has an environment with extremely severe corrosiveness. .

The present inventors, as a result of continuing research on the corrosion resistance of amorphous alloys, in addition to the alloys described in Japanese Patent Application No. 61-225435 and Japanese Patent Application No. 61-225436, by combining various elements, high temperature The present invention has been accomplished by finding that an amorphous nickel alloy having high corrosion resistance can be obtained in concentrated phosphoric acid.

The present invention comprises the first to fourth inventions set forth in claims 1 to 4, and the following first
The constituent elements and contents of these first to fourth inventions are shown in the table.

Action Amorphous alloys obtained by various methods for producing amorphous alloys, such as ultra-rapid solidification of a molten alloy having the above composition or sputter deposition, are single-phase alloys in which the above elements are uniformly solid-dissolved. Therefore, the amorphous nickel alloy of the present invention forms a protective film that is extremely uniform and guarantees high corrosion resistance.

In order to use a metal material in such an environment, it is necessary to give the metal material the ability to form a safe protective film because it dissolves easily in a high temperature concentrated phosphoric acid solution with weak oxidizing power. There is. This is achieved by making an alloy containing the required amount of active elements. However, in the case of a crystalline metal, if a large amount of various alloying elements are added, a polyphase structure having different chemical properties is often obtained, and a predetermined corrosion resistance may not be realized. Also, the occurrence of chemical heterogeneity is rather detrimental to corrosion resistance.

On the other hand, the amorphis alloy of the present invention is a uniform solid solution and is intended to uniformly contain a predetermined amount of effective element capable of forming a safe protective film. Such an amorphous nickel alloy has a uniform protective film, and exhibits sufficiently high corrosion resistance.

That is, the condition that a metal material having a weak oxidizing power and that can withstand concentrated phosphoric acid at high temperature is to have a high protective film-forming ability that a stable protective film is uniformly formed on the material in a non-oxidizing environment. This is realized by the alloy composition of the present invention, and the fact that the alloy has an amorphous structure allows an alloy having a complicated composition to be prepared as a single-phase solid solution, and ensures uniform formation of a protective film.

Next, the reasons for limiting the composition of each component in the present invention will be described.

Ni is a basic element of the alloy of the present invention, and Mo and
It is an element that forms an amorphous structure when the total amount of Cr and Ta coexists in a predetermined amount, and an element that forms an amorphous structure even when it coexists with P. Further, Ni is an element that assists the actions of Ta, Mo, and Cr, which are responsible for corrosion resistance.

Ta, Mo, and Cr are elements that form a protective film and play a role in corrosion resistance. Of these, the sum of Ta and other elements is 25-
When the content is 50 atomic%, since the metal-metal alloy of these and Ni can form an amorphous structure, the sum of Mo and Cr and Ta in the first to sixth aspects of the present invention is 25-50 atomic%. And P is an effective element that assists the formation of a protective film such as Ta, Mo, Cr, etc., but if added in a large amount to a metal-metal alloy, it becomes difficult to obtain an amorphous structure, and therefore, the third and fourth aspects of the present invention. In, P is less than 10 atomic%.

Further, the amorphous nickel alloy of the present invention contains 10 atomic%
Even if the following Nb and 5 atomic% or less of Ti and Zr are included, the object of the present invention is not hindered.

In the production of the amorphous alloy of the present invention, various methods which are already widely used, that is, a method of rapidly quenching and solidifying a liquid alloy, various methods of forming an amorphous alloy through a gas phase, and a method of forming a solid long by ion implantation are used. Any method of producing an amorphous alloy such as a method of destroying the periodic structure may be used.

As an example, FIG. 1 shows an apparatus for producing the amorphous alloy of the present invention. The part surrounded by the dotted line is filled with an inert gas after being evacuated. In the figure, reference numeral 2 denotes a quartz tube having a vertical nozzle 3 at a lower end thereof. A raw material 4 and an inert gas for preventing the raw material from being oxidized can be fed from a feed port 1 provided at the upper end of the quartz tube 2. . A heating furnace 5 is provided around the quartz tube 2 to heat the sample. A high-speed rotating roll 7 is placed vertically below the nozzle 3 and rotated by a motor 6. To prepare an amorphous alloy, a raw material 4 having a predetermined composition is placed in a quartz tube 2 and first,
The apparatus is evacuated to about 10 ^-5 Torr and then filled with an inert gas. Then, the raw material 4 is heated and melted by the heating furnace 5, and the molten metal is sprayed by the motor 6 onto the outer peripheral surface of the roll 7 which is rotating at a high speed of 1000-10000 r.pm by using a pressurized inert gas. Done. By this method, the amorphous alloy of the present invention can be obtained as a long thin plate having a thickness of about 0.1 mm, a width of 10 mm, and a length of about several meters.

Example Raw material metals were mixed so as to have the composition shown in Table 2, and a raw material alloy was produced by an argon arc melting furnace. These alloys were re-melted in an argon atmosphere and were rapidly quenched and solidified using the single roll method shown in FIG.
An amorphous alloy thin plate having a length of 01-0.05 mm, a width of 1-3 mm and a length of 3-20 m was obtained. The formation of the amorphous structure was confirmed by X-ray diffraction. The surfaces of these alloy samples were polished in cyclohexane up to silicon carbide paper No. 1000. Then, cut out the alloy raw material of the specified length, and about 63% P at 160 ℃
_It was dipped in a 72% P ₂ O ₅ solution of ₂ O ₅ and 200 ° C. for 7 to 10 days, and the weight before and after the immersion was measured using a microbalance.

 The results obtained are shown in Table 3.

The corrosion rate of the amorphous alloy of the present invention is extremely low. After the immersion test of the alloy of the present invention,
As a result of analysis using X-ray photoelectron spectroscopy, the alloy was Ta and
A hydrated oxyhydroxide protective film in which Mo was concentrated was formed, and it was found that this is the cause of the high corrosion resistance of the alloy of the present invention.

Effect of the Invention As described in detail above, the amorphous nickel alloy of the present invention is a highly corrosion-resistant alloy that forms a stable protective film even in a severe corrosive environment such as high-temperature phosphoric acid with poor oxide and is not corroded. .

In addition, since the alloy of the present invention can be applied to any of the widely used techniques for producing an amorphous alloy, a special device is not required again, and the alloy of the present invention is excellent in practicality. .

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of an apparatus for producing the amorphous alloy of the present invention. 1: Raw material inlet 2: Quartz tube 3: Nozzle part 4: Raw material 5: Heating furnace 6: Motor 7: High-speed rotating roll

Claims (4)

(57) [Claims] 1. A Ta content of 10-40 atomic% and a total content of Mo and Ta of 25-
Highly corrosion resistant amorphous nickel alloy with 50 atomic% and balance Ni. 2. A highly corrosion-resistant amorphous nickel alloy containing 10-40 atomic% of Ta and 25-50 atomic% of the total amount of three elements of Mo, Cr and Ta, and the balance being substantially Ni. 3. The total amount of Ta is 10-40 atomic% and Mo is 25.
A highly corrosion-resistant amorphous nickel alloy containing -50 atomic% and less than 10 atomic% P and the balance Ni. 4. A highly corrosion-resistant amorphous material containing 10-40 atomic% of Ta, 25-50 atomic% of the total amount of three elements of Mo, Cr and Ta, further containing less than 10 atomic% of P and the balance of Ni. Nickel alloy.