JP2911675B2 - High temperature corrosion resistant amorphous alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a new amorphous alloy which has excellent high-temperature corrosion resistance to withstand both high-temperature sulfurizing atmosphere and oxidizing atmosphere, and can be used in various industrial and consumer fields including chemical plants. .

[0002]

2. Description of the Related Art The present inventors have found various amorphous alloys exhibiting high corrosion resistance in a severely corrosive environment that cannot be tolerated by a crystalline alloy such as in a high-temperature concentrated acid. These amorphous alloys are roughly classified into metal-metalloid alloys and metal-metal alloys. A metal-metalloid alloy is composed of an iron group element such as Fe, Co, and Ni and a metalloid element such as P, C, B, and Si of about 10 to 25 atomic% necessary for amorphization, and has high corrosion resistance in an aqueous solution. Is C
This is realized by adding r. In contrast, metal-metal alloys are Fe, Co, Ni, Cu, Al
And the like, and IVa and Va group valve metals such as Ta, Nb, Zr, and Ti. In this case, the corrosion resistance in the aqueous solution is due to the valve metal constituting the amorphous alloy. Among them, the alloy containing Ta or Nb of the Va group has extremely high corrosion resistance.

[0003]

The alloy element that forms the most stable oxide scale in a high-temperature oxidizing gas environment is aluminum and then chromium. Has been used. However, the corrosion resistance of these elements to high-temperature sulfurization is not high. On the other hand, alloying elements that form sulfide scales having excellent protection in a high-temperature sulfide environment include molybdenum, tungsten, niobium, and tantalum.
However, elements with high resistance to sulfidation have no protective ability in an oxidizing environment due to the sublimation of oxides such as molybdenum and tungsten, and the formation of oxides much larger than metals such as niobium and tantalum. Therefore, a metal material that can be used in a high-temperature gas environment where sulfide and oxidity coexist has not been found.

However, in an actual high-temperature corrosive environment, the partial pressures of sulfur and oxygen fluctuate greatly. Therefore, the emergence of a metal material that can withstand both high-temperature sulfide and oxidizing environments has been desired.

The present invention utilizes the characteristics of an amorphous alloy forming a single-phase solid solution and the fact that amorphization by sputtering does not require melting for alloying, and uses a low boiling point oxidation-resistant metal and a high melting point sulfuration-resistant metal. The present invention provides a high-temperature corrosion-resistant amorphous alloy made of a conductive metal.

[0006]

Usually, an alloy is crystallized in a solid state. However, the alloy composition is limited so that the alloy composition is limited to be rapidly quenched and solidified from a molten state, or sputter deposited using a predetermined target. If a method that does not form long-period regularity in the atomic arrangement in the process is applied, an amorphous structure similar to a liquid without a crystal structure can be obtained. Such an alloy is called an amorphous alloy. Amorphous alloys are uniform single-phase alloys of supersaturated solid solutions, possess significantly higher strength than conventional practical metals,
And, depending on the composition, it shows various characteristics including abnormally high corrosion resistance.

The present inventors have created a new amorphous alloy and conducted extensive research on its properties. As a result, by using a sputtering method that does not require melting during the alloy formation process, the low melting point metal and the high melting point metal can be combined. It has been found that an amorphous alloy can be produced, and Ti, Zr, Nb, T
a, Mo, W, etc., Group IVa, Va and VI elements and C
We succeeded in producing an amorphous alloy composed of elements of group Ib and group IIIb such as u and Al. These one
Department is Japanese Patent Application No. 62-103296, Japanese Patent Application No. 63-515
No. 67, Japanese Patent Application No. 63-51568 and Japanese Patent Application No.
No. 260020. These studies were further continued, and as a result of trying to produce a high corrosion resistant metal-metallic amorphous alloy composed of elements between adjacent groups in the periodic table,
Amorphous alloys composed of Ti and Zr of Group IVa element and Cr of Group VIa element and Ta, Nb and VIa of Group Va element
Succeeded in the production of an amorphous alloy composed of elemental group Cr and previously disclosed in Japanese Patent Application Nos.
267542. The present inventors have continued these studies earlier, and as a result of examining the alloy formation conditions and the like, as a result, a highly corrosion-resistant amorphous aluminum alloy composed of Al and Cr, which are low melting point light elements, and various kinds of alloys for further improving the corrosion resistance. Successful preparation of amorphous aluminum alloy containing element, Japanese Patent Application No. 4-29362
And Japanese Patent Application No. 4-29365.

The present inventors have further studied the properties of the alloy thus produced, and as a result, have found a high-temperature corrosion-resistant amorphous alloy that can withstand both oxidation and sulfidation at high temperatures, which has not been realized until now. Achieved.

[0009] The present invention is defined in claims 1 to 9.
Table 9 shows the constituent elements and contents of the present invention.

[0010]

[Table 1]

(* 1) At least one kind of Mo and W (* 2) At least one kind of Ta and Nb (* 3) At least one kind of Zr and Ti (* 4) At least one kind of Fe, Co, Ni and Cu Species (* 5) Substantial balance (* 7) Total of at least one of Ta and Nb and at least one of Zr and Ti (* 8) At least one of Mo and W and Fe, Co, N
Total sputtering with at least one of i and Cu Sputtering is one method of producing an amorphous alloy, and sintering a target composed of a plurality of crystalline phases having the same average composition as the amorphous alloy to be produced but not a single phase. Amorphous alloys are produced by using a material prepared by melting or melting, or by mounting or embedding an element to be alloyed on a metal plate composed mainly of an amorphous alloy to be produced.

The present invention utilizes and improves this method and is as follows.

Although it is not so easy to produce an Al-Mo alloy target by a melting method or the like, an amorphous material having high high-temperature corrosion resistance is formed by a sputtering method using a target in which an Mo lump is placed on or embedded in an Al plate. An Al-Mo alloy can be obtained. In this case, in order to avoid the generation of non-uniformity due to the location of the generated amorphous alloy, for example, as shown in FIG. 1, a plurality of substrates 2 are rotated around the central axis 1 of the chamber in a sputtering apparatus chamber 6. It is desirable that the substrate itself also rotates. Further, in order to change the composition of the amorphous alloy to be formed in a wide range, for example, as shown in FIG. 2, one target 4 is a Mo plate and another target 5 is an Al plate, and these two targets are inclined with respect to each other. Then, the substrate 2 is placed near the intersection of the perpendiculars of the two targets, and these two targets are simultaneously operated while their outputs are suppressed by two power sources. The concentration of alloying elements in the amorphous alloy produced by this method can be freely changed, and as a variation, Ta, N
By combining various targets and methods such as using a target in which b, Ti, Zr, Fe, Co, Ni, Cu, Mo and W are embedded, various high temperature corrosion resistant amorphous alloys can be obtained. In the method using two targets, the revolution and rotation of the substrate are particularly necessary in order to produce a uniform amorphous alloy.

The alloy having the composition of the present invention produced by the sputtering method is a single-phase amorphous alloy in which the above-mentioned elements are uniformly dissolved. The amorphous alloy of the present invention, which is a uniform solid solution, has a very uniform protective film that guarantees high corrosion resistance. In order to use a metal material in an environment in which the sulfide and oxidizability of the environment change, it is necessary to give the metal material the ability to form a stable sulfide or oxide film. This is achieved by making an alloy containing the required amount of active elements. However, in the case of crystalline metals, the addition of a large amount of various alloying elements often results in a multiphase structure with different chemical properties, and a protective film that guarantees high-temperature corrosion resistance is not evenly formed, achieving the required corrosion resistance. May not be possible. Also, the occurrence of chemical heterogeneity is rather detrimental to corrosion resistance.

On the other hand, since the amorphous alloy of the present invention is a uniform solid solution and uniformly contains a required amount of effective element capable of forming a stable protective film, such an amorphous alloy has a uniform protective film. And exhibit sufficiently high corrosion resistance. In other words, a condition that a metal material that withstands a severe corrosive environment should have is that a stable protective film corresponding to each corrosive environment has a high ability to form a protective film that uniformly forms on the material. 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.

Ta, Nb, T called valve metal
i and Zr are elements that form an amorphous structure when coexisting with Cr. In this case, Ta, Nb, Ti and Zr
Does not have an amorphous structure if it is too large or too small. The first aspect of the present invention containing elements other than Cr and valve metal
In the section, it is necessary to contain at least one of Ta and Nb in an amount of 25 atomic% or more and less than 50 atomic%. In the second and third aspects of the present invention containing Cr and an element other than the valve metal, the total of at least one of Ta and Nb and at least one of Ti and Zr is 25 atomic%. More than 50
It must be less than atomic%. Further, in the fourth and fifth aspects of the present invention containing at least one of Ti and Zr as a valve metal, at least one of Ti and Zr is used to form an amorphous structure.
It must be contained at least 5 atomic% and less than 50% atomic .

Since Cr is an element forming a stable protective scale in an oxidizing atmosphere, it must be contained in the present invention in an amount of at least 30 atomic% as a substantial balance of the alloy.

The sulfuration resistance is ensured by alloying with Ta, Nb, Mo and W. Therefore, in the second and third aspects of the present invention in which the amorphous alloy is formed by including at least 25 atom% of the total of at least one of Ta and Nb and at least one of Ti and Zr, high sulfuration resistance is guaranteed. Therefore, at least one of Ta and Nb must be contained in an amount of 9 atomic% or more.

On the other hand, Mo and W are elements that impart sulfidation resistance, but in order to guarantee the formation of an amorphous structure in a Cr-valve metal amorphous alloy,
Mo and W can replace Cr, but not valve metal. Therefore, the first and second aspects of the present invention containing at least one of Mo and W
In the section, in order to guarantee the formation of an amorphous structure, the total of at least one of Mo and W and Cr of 30 atomic% or more needs to be 75 atomic% or less.
In item 3 , at least one of Mo and W and 30
It is necessary to make the total with Cr of at least atomic% less than 75 atomic%. Further, in the second and third aspects of the present invention, in which the alloy contains both at least one of Mo and W and at least one of Ta and Nb, at least one of Mo and W is used in order to assure sulfidation resistance. Species and Ta and Nb
At least one of the following. Further, in the fourth and fifth aspects of the present invention in which at least one of Ti and Zr is included as a valve metal, at least one of Ti and Zr is used for forming an amorphous structure.
It must contain at least 5 atomic%.
And W must be realized by containing at least one of more than 20 atomic% , and the oxidation resistance must be realized by containing 30 atomic% or more of Cr.

On the other hand, a part of the high melting point metal is Fe, Co, N
It can be replaced by i or Cu. However, the addition of a large amount of these elements lowers the sulfidation resistance.
In the third and fifth sections , Fe, Co, Ni, Cu
At least one element selected from the following must be 20 atomic% or less.

The alloy of the present invention is made by a sputtering method.
Usually, a target made of a sintered or alloyed multiphase is used in the sputtering method. However, it is extremely difficult to produce an alloy of low-boiling Al and a high-melting-point metal by an ordinary method including melting, such as the alloy of the present invention. On the other hand, the present inventors have previously found that an amorphous alloy can be obtained by using a target on which a small piece of an element for alloying is mounted on a plate of an element constituting the amorphous alloy.

[0023]

Next, the present invention will be described by way of examples.

REFERENCE EXAMPLE 1 A target having four Ta disks each having a diameter of 20 mm and a thickness of 1.5 mm placed on a circumference having a radius of 29 mm from the center of a Cr disk having a diameter of 100 mm and a thickness of 6 mm was used as a target. Using the apparatus shown in FIG. 1, a vacuum of 1 × 10 to ³ Torr was maintained while flowing Ar at a rate of 5 ml / min, and sputter deposition was performed on the rotating and revolving stainless steel and quartz plate substrates. . As a result of X-ray diffraction,
The resulting alloy was confirmed to be amorphous, and analysis using an X-ray microanalyzer revealed that its composition was a Cr-43 atomic% Ta alloy. The change in weight when this alloy was exposed to the air at 950 ° C. indicated that a dense oxide scale was formed according to the parabolic law. The oxidation rate constant is 2 × 10 to ¹¹ g ² c
m ~ ⁴ s ~ ^1, which was extremely small, indicating that the oxidation resistance was extremely high. The change in weight when this alloy was exposed to sulfur vapor at 950 ° C. and 10 to ² atmospheres indicated that a dense sulfide scale was formed according to the parabolic law. Sulfidation rate constant is 7
× 10 to ¹⁰ g ² cm to ⁴ s to ^1, which was extremely small, indicating that the sulfuration resistance was extremely high. Therefore, it was found that the present amorphous alloy has extremely high hot corrosion resistance.

Reference Example 2 An Nb disk and a Cr disk each having a diameter of 100 mm and a thickness of 6 mm were set as targets and attached to the apparatus shown in FIG.
While maintaining the vacuum at 1 × 10 ^-3 Torr while flowing at a speed of / min, sputter deposition was performed on the rotating and revolving stainless steel and quartz substrate. As a result of X-ray diffraction, it was confirmed that the resulting alloy was amorphous. As a result of analysis using an X-ray microanalyzer, this alloy was found to be a Cr-35 atomic% Nb alloy. The change in weight when this alloy was exposed to the air at 950 ° C. indicated that a dense oxide scale was formed according to the parabolic law. Oxidation rate constant is 1 × 1
It was found to be extremely small, that is, 0 to ¹¹ g ² cm to ⁴ s ^-1 and extremely high oxidation resistance. The change in weight when this alloy was exposed to sulfur vapor at 950 ° C. and 10 to ² atmospheres indicated that a dense sulfide scale was generated according to the parabolic law. The sulfidation rate constant is extremely small, 6 × 10 to ¹⁰ g ² cm to ⁴ s to ¹ ,
It was found that the sulfuration resistance was remarkably high. Therefore, it was found that the present amorphous alloy has extremely high hot corrosion resistance.

[0026] Using the apparatus of Figure 1 in the same manner as in Example 1 Reference Example 1 was subjected to sputter deposition in the Substrate of various combinations of targeting attachment of stainless steel and the quartz plate. As a result of X-ray diffraction, it was confirmed that the resulting alloy was amorphous, and the composition determined by analysis using an X-ray microanalyzer is as shown in Table 2. All of these alloys have extremely high hot corrosion resistance.

[0027]

[Table 2]

[0028]

[0029]

As described in detail above, the amorphous alloy of the present invention is an amorphous alloy containing Cr and a high melting point metal as essential elements easily produced by a sputtering method, and Cr has a protective property in an oxidizing environment. The high melting point metal is an alloy that forms a sulfide scale with excellent protection in a sulfide environment and has extremely high hot corrosion resistance.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a sputtering apparatus for producing an amorphous alloy of the present invention.

FIG. 2 is a schematic view showing an example of a sputtering apparatus for producing the amorphous alloy of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate's revolving axis 2 Substrate which rotates 3,4,5 Target 6 Sputter chamber

Continuation of the front page (72) Inventor Danielesky Marek Poland Krakow Fafary Ulitza 2-6 (56) References JP-A-62-233735 (JP, A) JP-A-55-138049 (JP, A) JP-A-4 -337053 (JP, A) JP-A-5-105996 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C22C 45/00, 45/10

Claims (5)

(57) [Claims] 1. An element containing at least one element selected from the group consisting of Ta and Nb in an amount of 25 atomic% or more and less than 50 atomic%.
at least one element selected from the group consisting of
A high-temperature corrosion-resistant amorphous alloy containing more than 0 atomic% and having a total of 75 atomic% or less of Cr and 30 atomic% or more as a substantial balance. Wherein Ta and at least one element 9, the total of at least one element selected from the group of atomic% and Ti and Zr 25 atomic% or <br/> on selected from the group consisting of Nb 50 At least one element selected from the group consisting of Mo and W in an amount exceeding 20 atomic%.
Seen, which substantially high temperature corrosion resistance amorphous alloys the sum of the remainder a is 30 atomic% or more Cr and 75 atom% or less. 3. A total of 25 atomic% or more <br/> on 50 and at least one element selected from at least one element 9 group of atomic% or more and Ti and Zr selected from the group of Ta and Nb At least one element selected from the group consisting of Fe, Co, Ni and Cu in an amount of less than 20 atomic%
(However, 0 is not included) , and these Fe, Co,
The total of Ni and Cu and at least one element selected from the group consisting of Mo and W in excess of 20 atomic% and Cr substantially in the amount of 30 atomic% or more is less than 75 atomic%. High temperature corrosion resistant amorphous alloy. 4. An element containing at least one element selected from the group consisting of Ti and Zr in an amount of 25 to less than 50 atomic% and at least one element selected from the group consisting of Mo and W in an amount of not less than 20 atomic%, and the balance substantially 30% A high-temperature corrosion-resistant amorphous alloy composed of at least atomic% of Cr. 5. An alloy containing at least one element selected from the group consisting of Ti and Zr in an amount of at least 25 atomic% and less than 50 atomic%;
e, Co, Ni and Cu containing at least one element selected from the group consisting of 20 atomic% or less (but not including 0) , and further containing Fe, Co, Ni and Cu, and Mo.
At least one element selected from the group consisting of
Containing at least 30 atomic% and containing at least 30 atomic%
High temperature corrosion resistant amorphous alloy consisting of r.