JPS5950745B2 - Highly corrosion-resistant amorphous nickel-based alloy with resistance to pitting corrosion, crevice corrosion, and general corrosion. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides pitting corrosion resistance that can withstand harsh corrosive environments and is easy to manufacture.
This invention relates to a highly corrosion-resistant amorphous nickel-based alloy that is resistant to crevice corrosion and general corrosion.

Common corrosion-resistant iron-based alloys and nickel-based alloys, e.g.
5US304.5US315, Carpenter 20(TM), Inconel 600(TM), Hastelloy C(TM), etc. have excellent corrosion resistance and are widely used in corrosive environments including chemical industrial equipment.

However, even if molybdenum is added to stainless steels such as 5US304.5US316, which do not have a very high nickel content, pitting and crevice corrosion will easily occur in harsh environments containing halogen ions; used only in

In addition, even with high nickel alloys such as Inconel 600, in harsh corrosive environments, the wall thickness rapidly decreases due to pitting corrosion, crevice corrosion, and general corrosion, which is critical from safety and economical standpoints. This has become a serious problem.

A method of improving the corrosion resistance of such ordinary crystalline alloys is to add a large amount of P, which is extremely effective in forming a uniform passive protective film, that is, self-passivating, in a normally corrosive environment with poor oxidizing power. is possible.

However, it has been impossible to add a large amount of P because it significantly deteriorates the mechanical properties, workability, etc. of the material and causes the problem of brittleness.

In addition, crystalline alloys contain many lattice defects, so even if they are made passivated by increasing the oxidizing power of the environment, a uniform passivation film cannot be formed, so sufficient corrosion resistance cannot be obtained. do not have.

In order to improve these drawbacks, the present inventors invented an amorphous iron alloy that is resistant to pitting corrosion, crevice corrosion, stress corrosion cracking, and hydrogen embrittlement, and filed a patent application (Japanese Unexamined Patent Application Publication No. 1983-1991). -4017, JP-A No. 51-4019).

Also, JP-A-51-12311, JP-A-51-12
Publication No. 312 discloses the following amorphous alloys having excellent strength and corrosion resistance.

In other words, "one or more transition elements from Group 8 of the periodic table, such as iron, cobalt, and nickel, one or more metalloid elements, and one or more elements from Group 6a, and their alloys. It is contained so that the melting point of the alloy is within +150°C from the highest temperature of the eutectic temperature of the binary system of the Group 8 element and the metalloid element, and the melting point is 300°C from the molten state. temperature range up to 1 per second
An amorphous alloy with excellent strength and corrosion resistance, which is characterized by being rapidly solidified at a cooling rate of 0.5°C or higher.

” and “one or more transition elements of Group 8 of the periodic table such as iron, cobalt, and nickel, one or more of nitrogen, aluminum, sulfur, and tin, and one or more metalloid elements. One or more of the Group 6a elements are added to
The eutectic temperature of the group element and any of the added nitrogen, aluminum, sulfur, tin, and metalloid elements is within +150°C from the highest temperature, and the temperature is 300°C from the molten state. ℃ temperature range with a cooling rate of more than 105℃ per second, ? An amorphous alloy with excellent strength and corrosion resistance.

”.

However, according to both of the above-mentioned publications, the composition range of the alloy components of the invention is not clear, and regarding corrosion resistance, it is stated that ``In other words, the addition of chromium, molybutton, and tungsten increases the crystallization temperature and increases the upper limit of the use temperature as an amorphous material.'' It has been found that it has high strength and corrosion resistance.

", and regarding the corrosion resistance, 1 mo
Although the corrosion loss due to natural immersion in I HCl is described one by one, each example concerns an iron-based amorphous alloy.

The present inventors have studied amorphous nickel-based alloys other than the amorphous iron alloy for which the present inventors previously applied for a patent, and found that amorphous nickel-based alloys are easier to manufacture than amorphous iron-based alloys, and 46%
It has been newly discovered that it has extremely high corrosion resistance, showing no corrosion even in harsh corrosive environments such as hydrofluoric acid solutions.

The present invention aims to provide a highly corrosion-resistant amorphous nickel-based alloy having excellent resistance to pitting corrosion, crevice corrosion, and general corrosion. That purpose can be achieved.

An amorphous nickel-based alloy containing 15 to 40 atom % of Cr and 15 to 35 atom % of P, with the balance substantially consisting of Ni.

Containing 25 to 40 atom% Cr and 5 to 35 atom% P, and A1 of 3 atom% or less. Mo of 10 atom% or less,
Contains less than 42 atomic % of one or more types of Fe, C
An amorphous nickel conductor alloy in which the total content of r, P, AI, Mo, and Fe is less than 60 atomic %, and the balance is substantially Ni.

Contains 35 to 40 at% Cr and 5 to 35 at% P, and further contains one or more of C and Si at 20 at% or less each, with a total of 15 to 35 at% of p, C, and Si.
An amorphous nickel-based alloy containing the remaining portion substantially of Ni.

Contains 45 to 40 atom% of Cr and 5 to 35 atom% of P, and further contains 20 atom% or less of C1Si and 1 of B.
The species or two or more species are P, C, Si.

Contains 15 to 35 at% of B in total and 3 at% or less of Al (However, in the case of Cr-P-B-Al system, AIo
, 5 at % or less) 10 at % or less Mo, less than 42 at % Fe, Cr, p,
An amorphous nickel-based alloy in which the total of c, Sl, B, AL MO, and Fe is less than 60 atomic %, and the balance is substantially Ni.

' Contains 55 to 40 atom % of Cr and 5 to 35 atom % of P, and further contains one or two types of C and Si of up to 20 atom % and B of up to 20 atom % (however, Ni-Cr
-p-13-5i system (excluding Si 5 atomic% or less), P
A highly corrosion-resistant amorphous nickel-based alloy containing a total of 15 to 35 atomic percent of , C, and Si, with the remainder substantially consisting of Ni, and is resistant to pitting corrosion, crevice corrosion, and general corrosion, and is resistant to pitting corrosion, crevice corrosion, and general corrosion.

The amorphous nickel alloy of the present invention further improves the high strength and toughness that are characteristic of amorphous alloys, and also contains chromium, which provides high corrosion resistance to the alloy, and a highly corrosion-resistant passive protective coating mainly composed of chromium, which has poor oxidizing power. It is possible to add a large amount of P, which is extremely effective for self-passivation and is naturally generated even in a harsh corrosive environment. Moreover, it does not contain defects that can become a starting point for corrosion, and the corrosion rate in a harsh corrosive environment can be reduced. It is a small alloy that is easy to manufacture.

This is the reason why the alloy of the present invention does not suffer from pitting, crevice corrosion or general corrosion even in severe corrosive environments and has an unusually high corrosion resistance.

Next, the present invention will be explained based on experimental data.

Various corrosion experiments were conducted on amorphous alloys having the compositions shown in Table 1.

For comparison, similar tests were also conducted on various commercially available stainless steels and high nickel alloys.

Corrosion tests were conducted at 30°C using IMH2SO4, 1NNaC1°1NHCl, 10%HF, 46%HF, 10%F.
eCl3 ・6H20 and 10% FeC13 at 60℃
6H20 solution by hanging it with a plastic wire and immersing it, and measuring the change in weight before and after immersion using a microbalance to evaluate general corrosion resistance and pitting corrosion resistance.

The crevice corrosion resistance was also investigated from the change in weight during an immersion test in which a Teflon plate was placed in close contact with a portion of the sample.

In 1MH2SO4 and INNaCl, an amorphous alloy not belonging to the present invention containing 3 at.% Cr had a corrosion rate similar to that of commercially available 5US3Q4, but as shown in Table 2 of the present invention, an amorphous alloy containing 3 at.% Cr did not belong to the present invention. Sample A1 containing the solid solution is only slightly corroded.

Sample/16. , 2-20, &, 26-27, Boiled 32-3
In No. 6, no weight change was detected at all in a one-week immersion test in a solid solution.

On the other hand, as shown in Table 3, the present invention samples 2 to 20, &
26-27, 5US304 has severe general corrosion, pitting corrosion,
It exhibits complete corrosion resistance even in HCI solution where crevice corrosion occurs, and no weight change was detected in a one-week immersion test.

In addition, in the harsh environment of HF shown in Table 4, general corrosion and crevice corrosion occur even in Hastelloy C, which is one of the currently used high nickel alloys and medium weight high grade alloys, but the sample of the present invention/f6.2 ~20, A26~32, Arashi 32~36
No weight change due to corrosion is detected.

The samples were immersed in 10% FeCl 3 .6H20 solutions at 30° C. and 60° C., which are commonly used for pitting corrosion tests on stainless steel, and the surfaces of the samples were observed and weight changes were measured. Table 5 shows the results.

Even in sample A21, which has a low Cr content, only slight corrosion is observed, and there is no dangerous form of corrosion called pitting corrosion.

In addition, not only the comparative examples 5US304 and 5US316L, but also the present invention alloys A2~
No. 20, A26-27, and A32-36 had no pitting corrosion or crevice corrosion, and no weight loss was detected.

To further clarify that pitting corrosion does not occur in the alloy of the present invention, INNaCl and 1MH2SO4+0, IN
The anode polarization curve in NaCl was measured to examine the presence or absence of pitting corrosion potential.

The results are shown in Table 6.

Although not only 5US304.5US316L but also all stainless steels are subjected to a pitting potential, the alloy of the present invention is not subjected to a pitting potential, is completely passivated, and no corrosion weight loss is detected.

As is clear from Tables 1 to 6 above, amorphous nickel alloys containing Cr and P are not susceptible to pitting corrosion, crevice corrosion, or general corrosion, and have an abnormally high corrosion resistance that is incomparable to current stainless steels and high nickel alloys. have

This excellent property is based on nickel, Cr, P
This is due to the coexistence of these two materials and the unique structure of this alloy, that is, the amorphous structure.

Addition of appropriate amounts of P, B, C, Si, and L is necessary and effective for obtaining an amorphous structure.

The addition of Mo also improves the corrosion resistance, and the addition of Fe takes economic efficiency into account by reducing the Ni content.

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

Regarding Cr, when it is less than 5 at%, pitting corrosion resistance, crevice corrosion resistance, and general corrosion resistance deteriorate, and when it is reduced to 40 at%
If it exceeds 5 to 40 at%, it becomes difficult to penetrate the amorphous structure, so it is necessary to keep it within the range of 5 to 40 at%.
Among these, good results are obtained when the content is 7 to 20 atomic %.

P is a necessary and effective element for obtaining an amorphous structure, and at the same time is an element that promotes self-passivation of the alloy.

In the first and second aspects of the present invention, it is difficult to obtain an amorphous structure when P is less than 15 at% or exceeds 35 at%, so P must be within the range of 15 to 35 at%. Among them, 20 to 25 atom%
The best results are obtained when

Further, in the third and fourth inventions, when P is less than 5 at%, self-passivation is not promoted and corrosion resistance is reduced, and when it is more than 35 at%, it becomes difficult to obtain an amorphous structure. It is necessary to keep it within the range of ~35 at.%.

In the fourth and fifth inventions, C1B and Si are also effective elements for obtaining an amorphous structure, but C and B.

The total content of one or more types of Si is 20 atomic %
If it exceeds , it becomes difficult to obtain an amorphous structure.

Note that if the total amount of one or more selected from C, Si, and B and P is less than 15 atomic % or more than 35 atomic %, it will be difficult to obtain an amorphous structure.

Therefore, the total of any one or more selected from C, Si, and 13 and P must be within the range of 15 to 35 at%, and it is best when it is between 20 and 25 at%. Get results.

Note that the C9Si effective for obtaining an amorphous structure,
Part or all of the f3 element may be replaced with another element effective to obtain an amorphous structure, such as Ge at 20 atomic % or less, Sn, As, Se, Te, N, etc. at 5 atomic % or less. Alternatively, two or more types can be substituted.

In the second and fourth inventions, AI is an element that makes it easier to obtain an amorphous structure, but if it exceeds 3 atomic %, it becomes difficult to obtain an amorphous structure.

Therefore, the effective range is 3 at% or less and 0.5 at%
is optimal.

Mo is an element that further improves pitting corrosion resistance, crevice corrosion resistance, and general corrosion resistance, but when it exceeds 10 at %, it becomes difficult to obtain an amorphous structure.

Therefore, it should be in the range of 10 atomic % or less, and optimally 2 to
It is around 3 atomic percent.

If Fe is contained in an amount of 40 atomic % or more, the unusually high corrosion resistance that is the object of the present invention will be slightly impaired, so the Fe content must be less than 40 atomic %.

In the second invention, the total of essential components Cr and p and optional components A I , Mo, and Fe is 60
If atomic percent is included, the unusually high corrosion resistance that is the object of the present invention will be somewhat impaired, so the total must be less than 60 atomic percent.

Further, in the fourth invention, essential components Cr, p
and selected components C, Si, B, and Al.

If the total content of Mo and Fe is 60 atomic % or more, the unusually high corrosion resistance that is the object of the present invention will be slightly impaired, so the total must be less than 60 atomic %.

Co less than 40 atomic %, Pt, Mn each 10 atomic % or less, V, Nb, Ta, W, Zr, Ti
, Cu, each of which is 5 atomic % or less, can be added to the alloy of the present invention to obtain an amorphous structure and have no adverse effect on corrosion resistance. can do.

Next, a method for manufacturing the amorphous alloy of the present invention will be explained.

A molten alloy having the composition of the present invention is prepared from a molten state by 10
An amorphous alloy can be produced by ultra-rapid cooling at a cooling rate of 4° C./second or higher.

If the cooling rate is slower than 104° C./sec, complete amorphization cannot be achieved, so it is necessary to perform ultra-rapid cooling at a cooling rate of 104° C./sec or higher.

In order to manufacture the amorphous alloy of the present invention, for example, first. 2. Any of the devices shown schematically in Figure 3 can be used.

In FIG. 1, reference numeral 1 denotes a quartz tube having a vertical nozzle 5 at its lower end, through which raw material 4 and inert gas can be introduced through an inlet 2 provided at the upper end of this quartz tube.

A nozzle 3 is provided below the quartz tube 1, and a spout 5 for spouting raw material 4 in a molten state is provided at the tip of the nozzle 3.

A heating furnace 6 for heating the nozzle 3 is provided surrounding the nozzle 3.

82 high-speed rotating rolls 8 are provided vertically below the spout 5 and can be circumscribed or slightly spaced apart.

The molten metal motor 7 heats and melts the raw material 4 in the nozzle 3 under an inert gas atmosphere in the heating furnace 6.
A rotated at high speed of ~6000r, p, m, 82
When continuously dropped and injected between the rolls 8, the molten metal is solidified and rolled to produce an amorphous alloy.

By adjusting the separation distance of the rolls and the falling injection amount of molten metal, the normal pressure is 30 to 40 μ, the width is 1 to 5 mm,
Ribbon-shaped amorphous alloys several meters in length can advantageously be produced.

The apparatus shown in Fig. 2 is the same as the apparatus shown in Fig. 1 until the molten metal is melted and dropped (1, 1 in Fig. 1,
2...7 is 1゜1.102 in Figure 2, respectively.
In the device shown in Figure 2, the molten metal is dropped onto the outer circumferential surface of a single disk rotating at high speed, and is ultra-quenched while forming it into a ribbon shape using centrifugal force. This is a device designed to do this.

In the apparatus shown in FIG. 3, a quartz tube 201 has a nozzle 202 at its lower end that ejects water in a horizontal direction, into which raw metal 203 is charged and melted.

204 is a heating furnace for heating the raw material metal 203; 205 is a heating furnace for heating the raw metal 203;
A rotating drum rotated at 0r, p, m, which is
In order to minimize the centrifugal force load due to rotation of the drum, it is made of a lightweight metal with good heat conductivity, such as an aluminum alloy, and the inner surface is lined with a metal with good heat conductivity, such as a copper plate 207.

208 is an air piston for supporting the quartz tube 201 and moving it up and down.

Raw metal is first charged through the inlet 201a of the quartz tube 201 by fluid conveyance, heated and melted in the heating furnace 204, and then transferred to the nozzle 202 by the air piston 208.
The quartz tube 20 faces the inner surface of the rotating drum 205.
1 is lowered to the position shown in the figure, and then at about the same time it begins to rise, gas pressure is applied to the molten metal 203, causing the metal to be jetted toward the inner surface of the rotating drum.

In order to prevent oxidation of the metal 203, an inert gas such as argon gas 209 is constantly fed into the quartz tube to create an inert atmosphere.

The metal jetted onto the inner surface of the rotating drum is brought into strong contact with the inner surface of the rotating drum due to the centrifugal force caused by the high-speed rotation, thereby being rapidly cooled at an ultra-high speed, and can be turned into an amorphous alloy.

Above is the first part. 2. According to the apparatus shown in FIG. 3, it is possible to produce a fibrous or ribbon-like amorphous alloy.

Next, the present invention will be explained with reference to examples.

Example 1 A raw material alloy (cooked 2) consisting of chromium atomic %, phosphorus 20 atomic %, and nickel balance was heated and melted by the method described above, and then rapidly cooled to obtain an amorphous alloy.

This amorphous alloy can be manufactured into a composition very easily and did not exhibit any defects in the tests shown in Tables 2 to 6 above.

In particular, as shown in Table 4, even in 10% and 46% HF solutions, which are harsh corrosive environments in which even Hastelloy C, one of the highest grade alloys in use, corrodes, the weight change due to corrosion causes microbalance. It was not detected even when used, demonstrating extremely high corrosion resistance.

As a result of the various tests shown in Tables 2 to 6 above, it was found that the alloy was resistant to pitting corrosion, crevice corrosion, and general corrosion in severe corrosive environments.

Example 2 A raw material alloy (A16) consisting of 7 at.% chromium, 18 at.% phosphorus, 4 at.% silicon and the balance nickel was heated and melted by the method described above, and then rapidly cooled to obtain an amorphous alloy.

Like the alloy of Example 1, this alloy is also easy to manufacture, and
In the tests shown in Table 6, the alloy had the same excellent properties as the alloy of Example 1.

Example 3 Chromium 5 at%, phosphorus 13 at%, carbon 2 at%, silicon 1 at%, boron 5 at%, molybutton 3 at%,
An amorphous alloy was obtained by heating and melting the alloy (A, 35), the remainder of which was nickel, by the method described above and then rapidly cooling it.

This alloy is also easy to manufacture like Examples 1 and 2, and although it has a lower chromium content than Examples 1 and 2, it has a lower chromium content due to the effect of molybdenum addition.
In the tests shown in Table 6, the alloys had excellent properties that were the same as those of the alloys of Examples 1 and 2.

Example 4 A raw material alloy (A36) consisting of 9 at% chromium, 13 at% phosphorus, 2 at% carbon, 1 at% silicon, 5 at% boron, 25 at% iron, and the balance nickel was heated and melted by the method described above. , an amorphous alloy was obtained by rapid cooling.

This amorphous alloy can be easily manufactured in the same way as in Examples 1 to 3, and despite replacing a large amount of nickel with iron, it showed similar results in the various tests shown in Tables 2 to 6 as in Examples 1 to 3. It has various properties.

The amorphous nickel-based alloy of the present invention can be easily constructed as a tape-shaped wire or thin plate, and has unusually high corrosion resistance and excellent mechanical properties that cannot be achieved with conventional practical metal materials. It can be used stably with materials.

Therefore, it is suitable for use as a material for parts that require pitting corrosion resistance, crevice corrosion resistance, or general corrosion resistance in harsh environments such as chemical plants.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the outline of an apparatus used for ultra-quenching the alloy of the present invention from a molten state by rolling, Fig. 2 is an explanatory diagram schematically showing an apparatus for ultra-quenching the alloy using a disk, and Fig. FIG. 3 is an explanatory diagram showing an outline of an apparatus for ultra-quenching using the same centrifugal method.

Claims (1)

[Claims] Contains 15 to 40 at% Cr and 15 to 35 at% P, with the remainder substantially Ni, and is resistant to pitting corrosion, crevice corrosion, and general corrosion, and is resistant to harsh corrosive environments. Corrosion-resistant amorphous nickel-based alloy. Contains 25 to 40 atom% of Cr and 15 to 35 atom% of P, and contains 3 atom% or less of AI, 10 atom% or less of Mo
, containing one or more types of Fe in an amount of less than 40 atomic %,
The total of Cr, P, AI, Mo, and Fe is 60
A highly corrosion-resistant amorphous nickel-based alloy that is less than atomic %, with the remainder essentially consisting of Ni, and is resistant to pitting corrosion, crevice corrosion, and general corrosion, and is resistant to harsh corrosive environments. Contains 35 to 40 at% Cr and 5 to 35 at% P, and further contains one or more of C and Si at 20 at% or less each, with a total of 15 to 35 at% of P, C, and Si. A highly corrosion-resistant amorphous nickel-based alloy that is resistant to pitting corrosion, crevice corrosion, and general corrosion and can withstand harsh corrosive environments. Contains 45 to 40 atomic % of Cr and 5 to 35 atomic % of P, and further contains 20 atomic % or less of C and Si. AI containing one or more types of B in a total of 15 to 35 atomic % of p, c, si, and B, and 3 atomic % or less
(However, in the case of Cr-p-B-A I system, AIo, excluding 5 atomic % or less), Mo of 10 atomic % or less, 40 atomic %
Contains one or more types of Fe and less than Cr. The total content of P, C, Si, B, AI, Mo, and Fe is less than 60 atomic %, and the balance is substantially Ni, making it highly resistant to pitting, crevice, and general corrosion that can withstand harsh corrosive environments. Amorphous nickel-based alloy. Contains 55 to 40 atom% of Cr and 5 to 35 atom% of P, and further contains one or two types of C and Si, each of up to 20 atom%, and up to 20 atom% of B (however, N1-Cr
-P -B-8i system excludes less than 5 atomic % of Si), P
A highly corrosion-resistant amorphous nickel-based alloy containing a total of 15 to 35 atomic percent of C, Si, and H, with the remainder substantially consisting of Ni, and is resistant to pitting corrosion, crevice corrosion, and general corrosion, and is resistant to pitting corrosion, crevice corrosion, and general corrosion.