FI98074C - Amorphous nickel alloy for use in corrosive environments - Google Patents

Description

98074

Amorphous nickel alloy for use in corrosive environments

FIELD OF THE INVENTION This invention relates to an amorphous nickel alloy having good corrosion resistance and suitable as a corrosion resistant material for harsh corrosive environments such as high temperature phosphoric acid.

10 Background of the invention

309, 310 and 444 Mo stainless steel and Cr-Mo-Ti steel are currently commonly used as structural materials in plants treating high temperature concentrated phosphoric acid. Even these materials are not corrosion resistant enough to withstand harsh corrosive environments such as high temperature concentrated phosphoric acid.

The present inventors have previously invented amorphous nickel alloys which are highly resistant to pitting, intermediate corrosion and uniform corrosion, and have been the subject of a patent in Japanese Patent Provisional Application No. 53-5720, JP Preliminary Application No. 61 - 210 143, by JP Preliminary Application No 62 33 735 and JP Preliminary Application 62 33 736.

In addition, the present inventors have continued their research while studying the various properties of amorphous alloys and have found that an amorphous nickel alloy with good corrosion resistance is available due to the formation of a stable protective film even strongly. in a corrosive acid with a weak ». oxidizing ability, such as in high temperature concentrated phosphoric acid, for which a patent has been applied for in Japanese Patent Applications Nos. •: 35 61 225 435 and 61 225 436.

JP Application No. 61,225,435 of 9,8074 covers the following four claims: 1) An amorphous nickel alloy having good corrosion resistance and containing 10 to 30 atomic% Mo, 15 to 23 atomic% 5 and the remainder substantially Ni : s.

2) Amorphous nickel alloy with good corrosion resistance and containing 10 to 30 atomic% Mo, up to 7 atomic% B and / or Si, and B and / or Si and P: a total of 15-23 atomic% with the remainder being essentially Ni.

3) An amorphous nickel alloy having good corrosion resistance and containing 10 to 30 atomic% Mo, 30 to 40 atomic% Cr and 3 to 20 atomic% P, the remainder being essentially Ni.

4) Amorphous nickel alloy with good corrosion resistance and containing 10 to 30 atomic% Mo, 30 to 40 atomic% Cr, 7 atomic% B and / or Si and B: a and / or Si and P in a total of 8-20 atomic%, the remainder being essentially Ni.

JP Application No. 61 to 225,436 covers the following seven claims: 1) An amorphous nickel alloy having good corrosion resistance and containing 20 to 60 atomic% of Ta and the remainder being substantially Ni.

;;; 25 2) Amorphous nickel alloy with good corrosion resistance and containing 1 to 25 atomic% Ta, 15 »· · * · * · * - 23 atomic% P with the remainder essentially

Ni.

3) Amorphous nickel alloy with a good body: 30 rose resistance and containing about 1-25 atomic%

Ta, up to 7 atomic% B and / or Si and B and / or • ·. A total of 15 to 23 atomic% of Si and P, the remainder being essentially Ni.

4) Amorphous nickel alloy with good cor-. ; 35 rose resistance and containing 10 to 40 atomic% Cr and 3 98074 15 to 23 atomic% P, the remainder being essentially Ni.

5) Amorphous nickel alloy with good corrosion resistance and containing 10 to 40 atomic% Cr, up to 7 atomic% B and / or Si and B and / or Si and P: a a total of 15 to 23 atomic% with the remainder being essentially Ni.

6) Amorphous nickel alloy with good corrosion resistance and containing not more than 20 atomic% of 10 Ta, Ta and Cr in total 10 to 40 atomic% and 15 to 23 atomic% P, the remainder being essentially Ni.

7) Amorphous nickel alloy with good corrosion resistance and containing not more than 20 atomic% of Ta, Ta and Cr in total 10 to 40 atomic%, not more than 7 to 15 atomic% of B and / or Si: and B and / or Si and P in a total of 15 to 23 atomic%, the remainder being essentially Ni.

Due to its high boiling point, concentrated phosphoric acid is particularly corrosive at high temperatures, so that no metal material is available that can be used safely. The alloys disclosed in the above-mentioned JP applications No. 61 to 225 435 and No. 61 225 436 have good corrosion resistance even in such an environment. However, there is a growing need to develop - !!! 25 add a variety of metal materials having a capacity of 4 · *; _ withstands such corrosive environments with very • * · * · * · * difficult to use ordinary metal materials.

DISCLOSURE OF THE INVENTION It is therefore an object of the present invention to provide for use an alloy, i.e. an alloy, which has the ability to withstand an environment which hardly passivates the metal because it * · is non-oxidizing and which is very strongly corrosive, • · such as high temperature concentrated phosphoric acid.

The alloy is usually in its solid state 35 in the form of crystals. However, when using the method 4 98074 which prevents the atoms from arranging for a long time on a regular basis during solid formation, for example by very rapid cooling from the molten state to solidify (solidify) by limiting the chemical composition of the alloy, a liquid-like amorphous structure is obtained. alloy. In most cases, the amorphous alloy is a uniform single-phase alloy consisting of a supersaturated solid solution. It has much higher strength than conventional commercial metals and various chemical composition-dependent properties, including abnormally high corrosion resistance. The present inventors have studied the exploitation of the properties of such amorphous alloys and have found an amorphous nickel-based alloy which has good corrosion resistance and is not susceptible to pitting, intermediate corrosion or uniform corrosion even in a highly corrosive aqueous solution such as aqueous or chloride ions, a patent for this alloy is filed in JP Preliminary Application No. 53-57,120. In addition, the present inventors have found another amorphous alloy having good corrosion resistance.

• I

and which is useful in highly corrosive environments such as boiling concentrated nitric acid. in an environment containing poa or, in addition, an oxidizer ♦ · · '· *; this alloy is patented by JP Preliminary Application No. 61-21,043. They have found an amorphous alloy having good corrosion resistance f · i V * 30 and useful in a highly corrosive environment such as boiling concentrated chlorine; patent for this alloy is applied for in JP Preliminary Applications Nos. * * 62 33 735 and 62-33 736. All of these are amorphous nickel alloys. Due to its high boiling point, concentrated phosphoric acid is particularly corrosive at high temperatures, as described above, and sufficient corrosion resistance is not achieved unless the alloy itself has the ability to form a stable protective film.

The present inventors have made further studies investigating various properties of amorphous alloys. As a result, they found that new amorphous nickel alloys are available which are highly corrosion resistant due to the formation of a stable protective film even in a highly corrosive acid with low oxidizing power, such as high temperature concentrated phosphoric acid in the above-mentioned JP-en applications. Nos. 53-57 120, 61-210 143, 62 33 735 and 62 33 736 in addition to those disclosed in U.S. Patent Application No. 61,225,435 and JP-15 in Application No. 61,225,436.

In addition, the present inventors have continued their research on the corrosion resistance of amorphous alloys and have resulted in the present invention by finding that amorphous nickel alloys with good corrosion resistance even in high temperature phosphoric acid are available due to the combination of various elements in the above JP chips. in addition to the alloys disclosed in Application No. 61-225,435 and JP Application No. 61-225,436.

The compositions of the alloys of this invention are set forth in the appended claims. Examples of compositions according to the invention are given in Table 1.

• · · • · «• 6 · · ·« «6 98074

table 1

Chemical composition of the alloys according to the invention (atom-Z)

Patent- Ta Mo Cr Mo. Cr Mo. N P Ni (* 1) end of standard no. 5 - 1 10-40 25 - 50 (* 2) part 2 min. 25 - 50 (* 2) end 10, max. part 25 2 10 - 40 25 - 50 (* 3) end part IQ 1 10 - 40 25 - 50 (* 2) less than 10 end part 2 10 - 40 25 - 50 (* 3) less than 10 end part 3 min. 1 15 - 30 (* 4) 10 - 23 (* 6) end part 3 15 - 30 (* 5) 10 - 23 (* 6) end part 15 Pu "part (* 1) Essentially Ni (* 2) Total with Ta (* 3) Total Mo, Cr and Ta (* 4) Total Mo and / or W with Ta 20 (* 5) Mo: the sum of n at least 3 atomic% with W, (* 6) the sum of B and / or Si with P, provided that the total amount of B and / or Si is up to 7% by atom v * 2 5 • ·

Amorphous alloys obtainable by various methods for preparing amorphous alloys: by cooling very rapidly and solidifying molten alloys with a chemical composition similar to those mentioned above, or by depositing them by a sputtering process, are single-phase alloys in which the above-mentioned The elements are uniformly dissolved, and any amorphous nickel alloy according to the invention therefore forms a very uniform protective film which guarantees good corrosion resistance. * 7 98074

The metal material easily melts in a high-temperature phosphoric acid solution with poor oxidizing ability. In order for the metallic material to be used in such an environment, it is therefore necessary to give the metallic material the ability to form a stable protective film. This is achieved by preparing an alloy containing the required amounts of active elements. However, in the case of a crystalline metal, the addition of large amounts of various alloying elements often results in a multiphase structure containing various chemical properties and the desired corrosion resistance cannot be achieved. The formation of chemical non-uniformity is destructive to corrosion resistance.

The amorphous alloy of this invention, in contrast, is a uniform solid solution and contains the necessary amounts of active elements having the ability to form a stable protective film, evenly distributed. Such an amorphous nickel alloy forms a uniform protective film which gives it good corrosion resistance.

More specifically, the condition that the metallic material must meet to withstand high-temperature concentrated phosphoric acid with poor oxidizing ability is ;;; the fact that it must have a good ability to form a stable protective film which must be uniformly formed in a non-oxidizing environment. This is achieved by the chemical composition of the alloys according to the invention, and the fact that the alloy has an amorphous structure enables the preparation of an alloy with a complex chemical composition in a single-phase solid solution. shape and ensures the formation of a uniform protective film.

• ♦. The following describes the reasons for limiting the chemical composition in the context of the present invention.

Ni is an element which forms a constituent of the present invention. · A base of 35 strip alloys which forms an amorphous structure in the presence of a predetermined amount of Mo and / or Cr and Ta and which also forms an amorphous structure in the presence of P. Ni promotes the effects of Ta, Mo, Cr and W, which provide corrosion resistance.

5 Ta, Mo, Cr and W are elements that provide corrosion resistance through the formation of a protective film. When the combined content of Ta and any of said other elements is 25 to 50 atomic%, their metal-metal alloy with Ni can form an amorphous structure. The co-content of Mo and / or Cr with Ta is therefore determined to be 25 to 50 atomic% in claim 2 of the present invention. However, in order to avoid duplication with the alloy disclosed in the above-mentioned JP Preliminary Application No. 62-33,735, Mo: In the case of an alloy-15 alloy-free ring, an alloy containing at least 25 atomic% Ta should have a combined Cr and Ta content of less than 30 atomic%. P is an active element which promotes the formation of a protective film formed by Ta, Mo, Cr or W. Since the addition of a large amount of P to the metal-metal alloy makes it difficult to obtain an amorphous structure, the claims of this invention state that the P content is less than 10 atomic%.

‘On the other hand, a high P content gets in the Ni-P alloy !!! to provide an amorphous structure of a metal-semi-metal alloy ;;; 25 formats. However, adding too much P

• · I

* · * Rather prevents the formation of an amorphous structure. Therefore, in order to obtain an amorphous structure, the P content is limited to the range of 10 to 23 atomic% in the claim 3 of this invention. Since an amorphous metal semimetal alloy containing a sufficient amount of P, has a good ability to form a protective film, can the present invention. the alloy according to claim 6 must have sufficient corrosion resistance even in highly corrosive high-temperature concentrated phosphoric acid if the sum of Mo: ": 35 and / or W with Ta of at least 1 atomic 9 98074% is at least Correspondingly, an amorphous metal-metal alloy may have sufficient corrosion resistance in a highly corrosive, high-temperature concentrated phosphoric acid if the sum of W of 5 at least 3 atomic% with W is at least 10 atomic%. in the case of a semi-metal alloy, the addition of too much Mo, W or Ta makes it difficult to obtain an amorphous structure.The total amount of Mo and W with Ta of 1 atomic% is therefore determined to be 10 at most 30 atomic% in claim 3 of the present invention, and the sum of Mo of at least 3 atomic% and W is given up to 30 atomic%.

B and Si are elements that are effective in forming an amorphous structure in the presence of Ni and can replace P. However, in order not to impair the film-promoting effect of P, it is not desirable to replace P with a total amount greater than 7 atomic% B and / or Si.

The amorphous nickel alloy may contain up to 10 atomic% Nb and up to 5 atomic% Ti and Zr without compromising the object of this invention.

Any of a variety of commonly used methods for preparing an amorphous alloy can be used to prepare the amorphous alloy of this invention, including a method of cooling and solidifying a liquid alloy very rapidly. , in which an amorphous alloy is formed through the gas phase, and a method of destroying the long-term structure of a solid by ion injection.

:: 1 Figure 1 shows an apparatus according to the invention. > T't. to produce an amorphous alloy according to Ku- • ·. in Fig. 1, a vacuum is sucked into the part surrounded by the broken line. and then filled with inert gas. In this figure 2 '· "there is a silica tube with a vertical nozzle 35 3 at the lower end, and the raw material 4 and the inert gas intended to prevent oxidation of the raw material 4 can be fed through the feed opening 1 at the upper end of the silica tube 2. A heating furnace 5 is installed around the carbon dioxide pipe 2 to heat the above-mentioned raw material 4. A roller 7 rotating at a high speed 5 is placed vertically below the nozzle 3 and is rotated by a motor 6. In producing an amorphous alloy, a raw material 4 , is charged to a silica pipe 2, and when a reduced pressure of about 1.3 10 Pa is first applied to the apparatus, the pipe is filled with an inert gas.

The raw material 4 is then heated and melted in a heating furnace 5, and the resulting molten metal is injected by means of a pressurized inert gas onto the outer surface of a roll 7 rotating at a speed such as 1,000 to 10,000 rpm under the action of the motor 6. The use of this method makes it possible to produce the amorphous alloy according to the present invention in the form of a long plate having a thickness of, for example, 0.1 mm, a width of 10 mm and a length of a few meters.

Brief Description of the Drawing: Figure 1 is a schematic diagram illustrating an apparatus for making an amorphous alloy of the present invention. In Figure 1: 1 = raw material inlet; 2 = silicon-25 oxide tube; 3 = nozzle part; 4 = raw material; 5 = heat; . * snout; 6 = engine; 7 = high speed rotating * · ’*’ roller.

Example: .i. · The raw metal metals were mixed to obtain the chemical compositions shown in Table 2, and the raw material alloys were prepared in an argon melting furnace.

• · These alloys were remelted under an argon atmosphere and cooled and solidified rapidly using the single roll method shown in Figure 1 to form amorphous alloy-35 slabs having a thickness of 0.01 to 0.05 mm, a width of 11,98074 1 to 3 mm, and a length of 3 to 20 m. structure formation was confirmed by X-ray diffraction. The surfaces of these alloy samples were ground with cyclohexane to the fineness of No. 1,000 silicon carbide paper. Alloy samples of a predetermined length were then cut, immersed in a solution containing about 63% P 2 O 5 and a temperature of 200 ° C for 7-10 days, and the weight was measured before and after immersion with a precision balance. The results obtained are shown in Table 3.

10 # i i 0 * • · · r · • * «· (• · 4 ··· ·« * »· J · f *« ·· «» * .0 * 0 *

i I

12 98074

Table 2

Chemical composition of alloys (atomic%) Sample

No. lii Ho Ho Cr Jf P

1 70 10 20 2 75 20 5 3 70 20 10 4 60 20 20 5 60 30 1 0 6 60 30 20 7 60 10 30 δ 60 20 20 9 61 24 15 10 56 24 20 11 65 10 20 5 12 55 20 15 10 13 60 30 5 5 14 63 10 20 7 15 62 20 10 8 16 43 30 15 7 17 49 40 5 6 18 56 10 15 10 9 19 57 20 10 10 3 13 98074

Sample No. Nj And Ho Cr I P

20 60 25 5 5 5 21 67 l 14 18 22 65 l 15 19 23 63 3 [5 19 24 61 5 15 19 25 60 20 10 10 26 63 3 15 19

27 64 20 5 II

28 63 3 10 5 19 2 9 6 1 5 1 5 1 4 M (B: 5) 30 61 5 15 15 l5 (Si: 4) 31 61 5 15 15 15 ΓΒ: 2 '.Si: 2, 32 64 3 1 6 16 I6fl3: 2 ', Si \ lj 33 62 3 1 6 1 iGΓΒ: f S i: lh / 34 63 3 15 19 35 66 5 10 19 36 66 10 5 19 37 56 15 10 24 38 61 17 3 14 (B: 5) 39 63 15 3 16 (Si: 3) 4 0 62 1 5 3 16 fl); 2 '.S i: 2.

98074 14

Table 3

Examples of the corrosion rate of the alloys according to the invention - 1 -2 (g · h · m) in phosphoric acid solution

Sam- 63% P1O5. 160'C 11% P, 0S.200'C

Teen No. 1 0.0622 0, 2 25 2 0.0331 0.154 3 0.0222 0.094 4 0.0182 0.146 5 0.0127 0.045 6 0.0133 0.046 7 0, 0635 0, 365 8 0, 053 1 0, 1 22 9 0.0201 0.090 10 0.0192 0.085 Π 0.059? 0.213 IZ 0.0195 0.136 13 0.0125 0.045 14 0.0355 0.185 15 0.0177 0.134 1 6 0, 0098 0, 035 17 0.0075 0.021 13 0.0347 0.201 19 0.0163 0.127 15 98074 Sample

No. 63¾ Pt0 ,. t60 * C 7 2% Ρ, Ο *. 200 ° C

20 0.0099 0.035 21 0.0345 0.210 22 0.0303 0.195 23 0; 0213 0.187 2 4 0, 0 1 9 7 0, 17 3 25 0, 02 33 0, 17 1 26 0, 0670 0, 25 1 27 0.0252 0.183 28 0.0233 0.195 29 0.0211 0.196 30 0/0208 0.196 3 1 0, 02 14 0.137 32 0.0625 0.244 33 0.0230 0.133 34 0.0435 0.353 35. 0.0403 0.282 36 0, 039 1 0, 2-37 37 0,0353 0,218 33 0, 04 10 0, 266 39 0, 0 4 0 7 0, 28 1 4 0 0, 0-1 1 3 0, 27 7 98074 16 Amorphous compounds according to the present invention the corrosion rate of the alloys is very low. By analyzing the surface of the alloy by X-ray photoelectron spectrometry after the immersion test of the alloy according to the present invention, it was found that the alloy had formed a protective film of concentrated Ta and Mo hydrated oxide or hydrated oxide hydroxide, and this was found to be due to the present invention.

Industrial Use The amorphous nickel alloy of the present invention is, as described in detail above, highly corrosion resistant so that it does not corrode due to the formation of a stable protective film even in a highly corrosive environment with poor oxidizing ability, such as high temperature phosphoric acid.

Since any commonly used known method for producing an amorphous alloy can be used to prepare the alloy of the present invention, it is not necessary to use special equipment, so that the utilization of the alloy of the present invention is excellent in practice.

• »« • «« • «· • ·« • · «· · • # # ♦ • · ♦ ♦ · ♦ ··· ♦ ♦ · • ·» ♦ ♦ · ♦ • · i »iU '· M ti it · # ».

Claims (5)

1. Amorphous nickel alloy for use in corrosive environment, which alloy contains Mo and Ta, characterized in that it contains Mo and Ta in total 25 - 50 atomic%, where Mo is more than 3 atomic% and Ta is 10 - 40 atom%, phosphorus 0-10 atom% and the rest is Ni. 2. Amorphous nickel alloy according to claim 1, characterized in that Mo is partially replaced by Cr. 3. Amorphous nickel alloy for use in corrosive environments, which contains at least one of the elements Mo, Ta and W, characterized in that Mo and W are in total 15-30 atomic% and the alloy 15 contains at least one of the elements P, B and Si, whose combined amount is 10 - 23 atom% and the remainder is Ni. 4. Amorphous nickel alloy according to claim 3, characterized in that W is partially replaced by Ta. 5. Amorphous nickel alloy according to claim 3 or 4, characterized in that Mo is present in an amount of at least 3 atomic%. Ill ··· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · - · ·