JPS5947400A - Method for removing oxide film from surface of zr and hf as well as its alloy - Google Patents

Abstract

PURPOSE:To remove thoroughly a titled film of various shapes without any problem in safety and the decrease in yield in an AC electrolytic treatment method in NH4F, by adding ammonium salt of such as citric acid or the like and specifying pH and current density. CONSTITUTION:Zr, Hf and an alloy thereof having an oxide film are subjected to Ac electrolysis in an aq. electrolytic soln. which contains 0.1-0.5mol concn. of NH4F and is adjusted to 5-6pH by adding >=1 kinds among NH4, Na and K salts of a citric acid, oxalic acid, and tartaric acid thereto. The current density in this stage is set at 0.02-0.5A/cm<2>. Then the dissolving rate of the base metal itself is suppressed extremely low, and the dissolving rate in the boundary layer part of the base metal and the oxide film layer is increased, whereby the oxide film is stripped from the base metal. If slight NH4NO3 is allowed to exist in the above-described aq. electrolytic soln., the power for stripping the oxide film particularly in the case of the Sn-contg. alloy is further improved.

Description

[Detailed Description of the Invention] This invention relates to Zr, Zr group combination, Elf, i
This relates to a method for removing and supporting the surface oxidation wave film of group A metals such as (, f-based alloys, etc.), or () alloys.
In general, most metals or @Kin iJ, fishing)'r'r
In the normal case, the oxide film is formed on the surface by fermentation, heat treatment, or use in a corrosive clay environment. ii) It was necessary to perform acid f arsenic film removal treatment. By the way, in recent years, with the remarkable development of the navigation industry, the nuclear industry, the water utilization industry, etc., the demand for Zr, Zr-based alloys, or Hf, Hf-based alloys has increased dramatically. 2.

In particular, for these alloys that are prone to form oxide films on the surface, removing the oxide film has a significant effect on the efficiency of the entire processing process.
It has come to occupy a certain position.

Conventional - Materials made of Zr, Zr-based alloys, IIf, C and IHi, b alloys; Removal of the hexagonal oxide film produced by 5 mechanical fl r4 vF cutting Alloy 'tj L
It was common for ZrF4 and Noah to be investigated and investigated immediately.

In the former case, the narrow H1l or the small concavity i′il+,
It is difficult to remove the coating of rough edges, and the base metal is also considerably etched away, resulting in a decrease in yield.

Since the oxidized coating 11 was extremely hard, the blades of the grinding machine were significantly worn. On the other hand, in the latter case +ct, high corrosion 1
Since raw molten salt is used once at a high temperature, there are problems in terms of overall surface and cost, and the millimeter speed of the base metal is extremely high, resulting in a low yield. There were some inconveniences, such as the need to remove the salt that had accumulated on the surface.

Therefore, in addition to this method of removing the f1 surface oxide film.

■ Nitric and fluoric acid treatment method■ HF scum treatment method■ 1'Although the 1' Jli4F treatment method, etc., was attempted, Q, 32. riq” from 811 fl, l (gold common) cicada speed 1 ru g) h sword・
Ui〈shi〉human 7;-MeG very wide film ((J,
J, /1]n 4'A 1jj-L length) can only be used by people, and till, gold Q)j total 1', "f
! There was an entry point that said f.

'Ma 7'h, Ifl F' Gas Knorr (-
Middle b 1 and (1, in) L 1 A 1
No/14.

First of all, JI F' ”J
O-6+1 (1 (14' (JJII heat, between the oxide film and the base metal (・7゛ accumulation fL'4a' direction C・) 1.
・Formation of '1-zerinu, rru, J-7nium oxalate: (n. 4 mol, ammonium citrate: (1,
l fi ”F=le, fluoride T 7 mo=lam: (
1,1mo・shi, jQ jL, :b111'19 f
t: 7J〈A.2:11.3 mol mixture (90-9
5C) 7. Mezuke shea (fluoridated juice, to bathe the proboscis)
-1 (j'4:1 method, but this) j method l'' *
l:'fl 'l! r product Q'ko1・ii1 (F -
t To use it? (I
Nokukasa Riki, Tsuku L1 Akira When does the second T strike become a problem?
Zircalo-1 square gold bath 1'14 in which oxidized oxides are formed in F'.
C7+ ['fil treatment method, which was emitted by liq, and -
CO-1A/rA (r)iff, %Chang1j4. '
This is a method of removing the oxide film by bathing all of the base metal to some extent, but this method was originally a process aimed at degrading the entire metal. Because it is a 111 treatment, local corrosion is severe and acid f
When used for the purpose of removing only the arsenic film, there was a problem in that the remaining part of the oxide film and the large amount of 4g eroded part of the base metal were mixed together.

From the above-mentioned viewpoints, the inventors of the present invention have developed a method that can completely process even irregularly shaped articles without causing any problems related to safety or yield reduction due to excessive metal loss. , and as a result of research to find a method for removing the surface oxide film of rVa group metal-based alloys with low processing costs,
I have come to the following knowledge as faJ~(e)Vko7JRizu. Namely.

(at Zr, Zr-based alloys,) lf-, H-, f-based alloys have a surface te coating, which has high electrical insulation properties, but it is possible to apply an AC voltage of 200 V or less in a tungsten solution. When a certain amount of water is allowed to flow completely, dielectric breakdown occurs over the entire surface 4.
1: Di1 surface oxide film, diameter 1.0 that reaches down to the base metal
~10011m small hole/my? 'Hlx density'.

1) Figure 1 shows a sample of Zircaloy-4 in which the specimen is placed in an aqueous solution of monomonium fluoride. This is a photographic diagram showing the condition of ``11'', which was published 5 minutes later. (visible) is colored 13.

Shikamo, Kono phenomenon Qj, bullion possible 11i fm Ka4”
)04r(E Even if the surface is 1 self ()
Q(2”t9. (acid) 1), so the clause 1
Part 11 of the existence rL (- is recited in (1) and N1. And the part of the membrane rupture, ! 5 Jim degree IR1Σノ, even if it is above, it has a protective metal) part) - p is 1
-I-1 - 5ttm, and the rest of the area is full of many cracks and 1 hole. Application of [), dielectric breakdown]? lCf-[-same, II%) flat is J' ~ big C is also music arrangement η1Hic← 工]? 1. I don't have anything to do, and I don't have anything to do. Unlike il', l11'f, the purpose is to cause dielectric breakdown)l), and the heated object is 44f, ll'41! Even if the
Can llll holes be formed? - and.

fb, l fL "It is well known that ammonium layer liquid is commonly understood as IVa group metal J. When potassium salt or aqueous M of a mixture thereof is added to maintain the pH at 5 to 6, the mm velocity of the metal itself is suppressed to an extremely low level, and rather the boundary layer near the interface between the metal and the oxide film layer is suppressed. The mm velocity of the part increases.

FIG. 2 is a photographic diagram showing the progress of corrosion due to the treatment solution.V, the upper left is the base metal, and the lower left is the oxide film. The lower part of the part 14° that appears white due to the oxide film is an area that has already been corroded and has lost its bond with the base metal.

(c) Therefore, in an aqueous ammonium fluoride solution.

Ammonium, sodium, and potassium salts of citric, oxalic, or tartaric acids1. Or add water to these mixtures in an electrolyte bath solution to maintain pH at 5 to 6.* Zr, Zr groups and I(f, Hf
When an alternating current is applied at a specific current density to the surface oxide film of the base alloy,
It is possible to form all uniform pores in the oxide film that reach the base metal, and furthermore, there is no bond between the oxide film and the base metal in these pores, and the oxide film is peeled off from the base metal.

The presence of a small amount of ammonium nitrate in the tdl precontaining electrolyte solution further increases the ability of acid arsenic films to be removed, especially on SNK-containing alloys.

(e) I, , Since the mechanism is as above, 1
Hydrogen gas is generated on the surface of the metal by 711,
'When ultrasonic vibrations are applied to the solute solution, it replenishes new liquid to the boundary layer, promotes the diffusion of eluted metal ions to the outside from the gap, or promotes bonding. Benefits of 9'b, such as promoting the peeling of loose oxide films, can be obtained. And hydrogen scum is generated: J.

The power of hydrogen peroxide! This invention was made based on the above knowledge, and the running speed will be increased accordingly.]
and a Z r , l r based alloy with an oxide film, 1
1! , Hf, Hf4 alloy, ammonium fluoride l'A
tit: : (1°1 to 0.5 mol, or further, the ammonium fluoride A +7) 1/100 to 11
Contains at least one unit of 8% hydrogen peroxide of 1710-1/2 of ammonium and ammonium fluoride, and citric acid.

In an electrolytic aqueous solution in which PII 5-6 was maintained by adding one or more of oxalic acid, tartaric acid, ammonium salt, sodium salt, and potassium salt, the! , or ultrasonic vibration ``I!'-The city'3 mark on the dehydrated liquor 7JII Ligarh 1hr flow density: O-
02-0-5 A/al is the amount of alternating current; by understanding,
It is characterized by efficiently removing the surface oxide film without excessively dissolving the base metal.

Next, regarding the method of the present invention, the reason why the composition of the LLI liquid, the PI3, and the current density are limited to 17 as described above will be explained.

ω Ammonium fluoride concentration Figure 3 shows the influence of ammonium fluoride degree in the water bath liquid on the applied pressure required to obtain the same current density when Zircaloy-4 is used as the treated material. FIG. 4 is a diagram showing the influence of liquid concentration on the mm velocity of the same material to be treated, as is clear from these diagrams.

If the ammonium fluoride concentration is less than 0.1 mol, the applied voltage will be high and the rate of deterioration of the treatment liquid will also be rapid, making treatment work difficult. On the other hand, the ammonium fluoride concentration is 0.
If it exceeds 5 moles, the corrosion rate becomes excessive and local corrosion tends to occur, and the buffer agent added at the same time becomes supersaturated and precipitates at a considerably high temperature, which is not preferable. For this reason, the ammonium fluoride concentration f in the electrolytic solution was determined to be 0.1 to 0.5 mol.

■PH value Figure 5 is a diagram showing the influence of PH on mm speed, and Figure 6 is a diagram showing the influence of PH on the applied voltage required to obtain the same current density. From too,
P) If 1 is less than 5, the corrosion rate will be excessive and the local S
If corrosion occurs and - exceeds 6, the amount of power consumption increases even though the corrosion rate decreases, which is not preferable, so both values were set at 5 to 6.

When conducting the experiments shown in Figures 5 and 6, it should be noted that if the value is less than 5, the quality of ammonium citrate and ammonium oxalate will deteriorate, and if it exceeds 5, the quality of ammonia will deteriorate. The concentration of the ω-ra buffer was adjusted to the desired value by adding ammonium nitrate, hydrogen peroxide, and ammonium salts of citric acid, oxalic acid, or tartaric acid.

n) Concerning the concentration of buffering agents such as IJium salt and potassium salt, the pH value of the solution should be adjusted to 5 to 5 for 60 to 120 minutes, which is the upper limit time required to remove the oxide film using the treatment solution.
In order to maintain the ammonium nitrate concentration at 1.5 times the ammonium fluoride concentration as shown in Figure 7, it is sufficient to maintain the ammonium nitrate concentration between 1/10 and 115 times the ammonium fluoride concentration. [The reason why t is determined is that in the case of alloys containing Sn such as Zircaloy, the content is limited to 1 to 2 q6 at most.

In addition, the hydrogen peroxide concentration was reduced to 1/1 that of ammonium fluoride.
The reason for setting the concentration to be 0 to 1/2 is that if the concentration is less than 1/10 of the ammonium fluoride concentration, it will be difficult to maintain the foaming effect on the surface of the treated object for the necessary time; If it exceeds 2 ft, foaming on the surface of the object to be treated will become excessive, and the liquid level will rise excessively due to the foaming.

■ Current density If the current density (M degree is less than 0.02 A/al), there will be less bubble generation during treatment and the effect of promoting oxide film peeling will be weak (on the other hand, if it exceeds 0.05 A/-, the liquid level will rise due to excessive foaming. In addition, the temperature of the liquid increases considerably with each energization, reaching a temperature of 7 oc or more, requiring cooling.Furthermore, the metal bath output also increases, causing a drop in yield. Therefore, the current density is set to 0002~0,
5 A/cJ.

Regarding the temperature of the treatment solution, as is clear from the diagram showing the influence of solution temperature on bath decomposition speed in Figure 8, the corrosion rate increases as the temperature increases, but foaming occurs when the temperature exceeds 70C. It becomes excessive.

If the temperature exceeds 80'C, this phenomenon may become extremely severe, so it is preferable to keep it below 700C.

Note that the data shown above is for Zircaloy-4, but it also applies to other Zr and Zr-based alloys.

Similar results were obtained for Hf and Hf-based alloys. By the way, in carrying out this 8-day process, as a pre-treatment for the electrolytic treatment, a thermal shock or a mechanical shock is applied to the treated material. -, j, it is preferable because a slight rack is formed in the oxide film, making it easier to peel off the oxide film, and
After carrying out the method of this invention, some C) implantation-
If j%B oxide 1g film remains t, -C and ξ, then
After treatment, residual 11C4 can be easily removed by immersion in a nitric-hydrofluoric acid bath or by sanding with a metal brush. It was also confirmed that when immersing in a nitric-hydrofluoric acid solution (PI-1), a better effect can be obtained if the entire ultrasonic wave is oscillated in the treatment solution.

1.2 Next, Jin's invention will be explained with examples.

Example 1 First, the component composition is Sn: 1.50 MC'@', a
, F'e: (1,20M1%, Cr:0,10 heavy fa
%, Nl: 0-002'i ii%, zr
: The remainder is Zircaloy-4 tube (outer diameter:] 0.7E.

Thickness: 0.62F+, length: 100ffIL, oxide film J”t: 3~5μtn depending on the part)
The paddy was harvested and then subjected to a surface decontamination experiment as shown in Figure 9. ? carried out. In Figure 9, the work is a fluororesin beaker, 2
31.1.7 /Me, resin coated heater, 4
is fluorine side 11t & subject 11, ^i:, +-iii,
5 is an ultrasonic cleaner, 6 (l-j: car tTτMt, 7
＆Yoyama 6i mouth: l * N is 1 sushi datsuk.

So [, te, at this time Tll release 1'' mouth, 1, 1, ;1
1: Noto 1...C was present. Processing liquid composition: Ammonium fluoride...-0゜:j[ru.

6.1 Ammonium...0005 Monoden.

Ammonium oxalate (). l-1 nil.

Ammonium citrate...l7 (.

Hydrogen peroxide...0.1 mol.

Liquid phase: 700 e.

pH of liquid: 5.

Current density: (1,1A,/cd).

Liquid temperature near (JC.

Processing time: 40 minutes.

After the electrolytic treatment, we observed the surface of Zircalo 4-11'f, which was the material to be treated, and found that the oxidation @119 was completely φ'I +'
:li was confirmed to have been removed.

Actual M example 2 1117 line f article f1.

Processing yM Jitla: Ammonium fluoride...
0.1 mole.

Ammonium citrate ~0.5-r, liquid elbow 0
0m! , Cover PII: 5.

Current density: 0003A/d.

Liquid temperature near 0C.

Processing time: 90 minutes.

The procedure was the same as in Example 1, except that Shirutsuno0E! 1
'#After the complete treatment, it was confirmed that the Yani oxidation was completely removed and removed.], Implementation M+ 3) If plate material (width: 20 baits, J width: 2 Tomi), costume: IQQII11. ．． Oxide film If: 61tm)
AC electrolysis was carried out using the AC electrolysis surface decontamination experimental apparatus 6 as shown in Fig. 9.The electrolysis conditions at this time were as follows.

Treatment W Composition: Ammonium fluoride...0.5 mol.

Ammonium citrate...1.5 mol.

Fluid transfusion 00mg.

liquid, [+: 5, Skin flow density: 0.5A/, -4.

Liquid temperature near 0C.

Processing time: 260 minutes.

After the electrolytic treatment, it was confirmed that the oxidation film had been completely peeled off and removed after the electrolytic treatment.
1. Electrolytic conditions: Liquid temperature: 65C.

City, areal density: Maintain 0.1Δ/d (however, 7. mark) Jl+
Kushiru+:j, .

The initial stage was 130V, and the final stage was fiOV).

Ultrasound: Taken during the dissolution process.

744. in Article 1.1 of the same example as Example 1, except that
One bamboo treatment was carried out.

After treatment, it was observed that a grey-brown scale (consisting of zirconium oxide '1q' as the king) with no sag was attached to the surface of Zircaloy-4W.

This scale is similar to the initial black oxide film.

The scale was loosely bonded to the base metal and could be easily removed by scrubbing with a wire brush.Therefore, as a post-treatment, 28 mol of Kol-L nitric acid was used.

In a solution of 0.5 mol of hydrofluoric acid, 3
When the tube was soaked in a vat for 0 minutes, the oxide film was completely removed from both the inner and outer surfaces of the tube.

In addition, the corrosion rate was calculated based on the peeling of the oxide film, the extraction of the base metal, and the inclusion of metal.

@1 stage processing: 61.4 ”F/ drr?/ynim
.

Post-processing: 45.4 cape/dm’/m.

Met.

Example 5 Zircaloy-4 tubes were treated under the conditions of Examples 4 and 42, except that ultra+1 wave vibration was not applied during the treatment.

As a result, the corrosion rate is.

1st stage processing: 53.7ki/dii/-1 descent processing: 43
．． 8 #v/dn? The amount decreased to 7 ml'q, and the remaining one spot of the black oxide film was graded F and Y.

Example (5) Except for not adding hydrogen peroxide to the composition of the treatment solution:
↑Zircaloy-1'f under the same conditions as Example 4? %・
I did it immediately.

As a result, the corrosion rate of ff1l treatment: 45-8 W/dn? /n+'q
.

and a decrease in bubble generation was observed.

Implementation IQ 7 Implementation f! Zircaloy-41i with four pillars in Al 4
! j, first hold 6oocK and f? :, ? lS evening I
After the temperature reached the desired temperature, the operation was repeated three times in total. Even if it is the same place + 11 + Φ production as in Example 4, the applied cloth, IE: 80V (initial) ~ 4 (J V C
It was also possible to give a military flow density of IA/ryrl. oxidized lJI with a treatment time of 45 minutes.
As mentioned above, with this invention, it was possible to remove the film and obtain a clean surface with a metallic luster without having to worry about rapid processing.
For removing oxide films from r-based alloys, Ilf-based alloys, and Hf-based alloys.

(II) The oxide film on the narrow parts and the four parts can be easily removed.

(11) The loss of I of the bullion is small and the yield is increased.

In other words, the elution of the base metal is limited to a thickness in the range of 40 to 80 μm, and can be processed using inexpensive equipment and material.
7. Easy-to-handle 50Hz or 60Hz AC power source can be used as is.

(vl Operation safety is high.

As shown in No. 9M, two objects to be processed can be processed at the same time.

θ) Removal of the acid and arsenic film formed on the surface of the ingot during casting of Zr, Zr-based alloys, or Hf, Hf-based alloys.

Similarly, removal of oxide film formed on the surface of forged products during forging.

(Same as 1111, removal of oxide film formed on the surface by heat treatment.

Q: Similarly, removal of the surface oxide film formed during the 1411 process in the eclipse environment.

(V) Z where the surface oxide film is formed Il'4
r + Z on the left) Removal of oxide film as il treatment for scrap recovery of gold, Hf, and Hf-based alloys.

It can be applied to other areas to obtain excellent results, etc.
Industrially useful effects are brought about.

[Brief explanation of drawings]

Figure 1 shows how the dielectric breakdown reaction of the metal tungsten film begins due to the space stamp IJI+ in the liquid. IT electron microscope photograph, Figure 2 IrJ, electron microscope photograph showing the state of corrosion caused by electrolyte, Figure A, Figure 3 shows the influence of liquid concentration on the applied pressure necessary to obtain the density of the opposite claw part. Figure 4 is a diagram showing the influence of lateral concentration on the liquefaction rate, Figure 5 is a diagram showing the influence of 1J on the resistance to jII\sinking μl-, and Figure 6 is a diagram showing the influence of ml- on the commercial flow of ml-. A green diagram showing the influence of -1 on the mark n' y F, which is necessary to obtain 1 [dense black], Figure 7 is a diagram showing the influence of liquid composition on changes in pH value,
Figure 8 is a diagram showing the influence of liquid temperature on the bath M velocity, Figure 9 is a schematic diagram of the dyeing equipment 11 on the surface of the father's flow, and Figure 10 is the acid coating that has been cracked by pretreatment. It is an electron micrograph diagram showing gold. In the drawing. 1... Beaker made of fluorine resin. 2... Treated material. 3...Fluororesin coated heater. 4...Fluororesin coating temperature singing. 5... Ultrasonic cleaner, 6... Voltmeter, 7... Electric 5
Flowing Tears, 8...Sly Duck. Applicant Mitsubishi Metals Co., Ltd. nn Person g L (l fll Husband r/1 or 1
Name - P≠ 1 Fig. In'++Y1 Fig. 2 0Pm 乍3m Gaku4 Fig. 7-/I Lγnt nif 4 skin, llEmOQ) Reed 5 Fig. Qin 7 Fig. Procedural correction divination (spontaneous) October 8, 1982 Kazuo Wakasugi, Commissioner of the Japan Patent Office 2 Name of the invention: Method for removing surface oxide film on Zr and Hf and their alloys 3, Person making the amendment 4, Agent! 11/11 Tokyo 111-ku Kami 111 Nishikicho-
Contents of Supplementary 1F, 7th Floor, 8th Floor, Soho Daini Building, No. JII'23 As attached (1) At the top of the specification, detailed explanation of the invention, in each of the above locations, the word "film" is replaced with "film" in 3J Correct. ■Specification, page 13, line 17, and 181f,
■ Specification, page 12, line 2 (2 places), line 6, line 12, and line 16, ■ Specification, line 15, line 7, ■ Specification, page 17, line Head 7 and line 9, ■ Specification, page 19, line 11, ■ Specification, page 2 (), line 7, ■ Specification, page 22, line 20. (2) Specification, No. 0, Detailed Description of the Invention, A111, Lines 17 to 18, ``Applying the specified h(electrical θ11 current -4- and 1.!-
A certain Ryo-1 corrects 11- ``When applied.'' (3) il' +lJ-ru0 according to Figure 7 as attached.
8. List of attached documents (1) Corrected drawings (Figure 7) 1. Tools 1.

Claims (4)

[Claims] (1) Zr and Hf with oxide film, and
ammonium fluoride concentration = 0.1 to 0.5
Mol. And, by adding one or more of ammonium salt, sodium salt, and potassium salt of citric acid, oxalic acid, and tartaric acid, P1]5 to 6f: Current density = 0 in the maintained electrolytic aqueous solution. .02~0,5 A/r
It is characterized by AC electrolysis at J. Zr and Hf
In addition, a method for removing the thorny oxide film on those alloys, (2) Zr and Hf having an oxide film, and their alloys, ammonium fluoride concentration: 0.1 to 0.5 mol, ammonium nitrate concentration: 1/1 of ammonium fluoride
00~J15 ri″11 degrees, and ammonium salt of citric acid, oxalic acid, or tartaric acid, sodium J
In an electrolytic aqueous solution that has a pH of 5 to 6 by adding one or more of I, Kariuno, and Hanawa, Ichi,
Areal density: 0. (The general oxidation wave tl'ii l!,'I removal method of Zr and Hf and their alloys, characterized by alternating current electrolysis at 12~0°5 A/- (3) Zr and Hf with oxide film, 111? Hini Sore Cl alloy. Ammonium fluoride, concentration: 0°1~(). 5 mol, hydrogen peroxide concentration: 1/1.0 of ammonium fluoride
]/2 1 degree. And, ammonium salt, sodium salt, and potassium salt of citric acid, oxalic acid, or tartaric acid are added to the electrolytic aqueous solution in which Pt+ 5 to 6 is maintained by adding one or more of these. 1 le: 0゜()2~0.5
A, /J to understand the y style 1''I! +' sign. Method for removing surface oxide film of Zr and Hf and their alloys, (4) Zr, Hf, and other alloys with oxide films. Ammonium fluoride concentration = 0.1-0.5 mol. Ammonium nitrate concentration: 1/10 of ammonium fluoride
61 degrees from 0 to 115. Hydrogen peroxide concentration: 1/1o to 1/1 of ammonium fluoride
2 #11. and in an electrolytic water bath solution maintained at P115-6 by adding one or more ammonium salts, sodium salts, and potassium salts of citric acid, oxalic acid, or tartaric acid. Density: 0.02~0.5A
A method for removing a surface oxide film of Zr, Hf, and alloys thereof, the method comprising performing alternating current electrolysis at a temperature of /4. +51 Zr squares and Hf having an oxide film, and their alloys, ammonium fluoride concentration: 0°1 to 0.5 mol. At the same time, the ammonium salt of citric acid, oxalic acid, or tartaric acid, triuric acid salt, and 1% or more of citric acid, oxalic acid, or tartaric acid are maintained at full strength for at least 1 day to maintain Pl (5 to G), and ultrasonic imaging Apply motion (, fr, Tft
In the dehydration bath, the air flow density is 20. 02～・0゜5A/
s Zr” characterized by AC electrolysis in L-4
Yohi Il, f51F・hiυ (-surface oxidation of those alloys Ilψ removal force method, (6) oxidation) IU? has Zr
Maru-, I O-Jl, r, ', fly, lj,
)III-t-these alloys. Ammonium fluoride concentration 11: 0° 1 to 0° 5 mol 5 ammonium nitrate J, concentration:
1/10 of ・(1−−・+15 q) +, l; 711
η. And, Kuen l''t, Schiff, Tsuji ('',!tμ-
6') Ammonium salt, sodium A in the current month
J4'4, and Kariuno, 11■] By adding A4 or higher), 115 to 6 minutes iN [1〒, with the addition of super t1 wave vibration i+ill (r-marked) J] 1
In a 7 m water solution, the flow density is 20°. 02～
Z, characterized by the exchange and decontamination at 0゜fiA/-
r: Method for removing surface oxide film from alloys of I, ITf, ID D' and others. +71 Zr o, which removes the oxide film, 11f,
Parallel example-'(-These alloys. Ammonium fluoride concentrated IF: 0.1 to 0.5 mol. Hydrogen peroxide @ degree: Ammonium fluoride J. l/10 to 1
/2 concentration. By adding one or more of ammonium salt, sodium salt, and potassium salt of potassium, citric acid, oxalic acid, or tartaric acid, P)l 5 to 6 is maintained, and ultrasonic vibration? It is characterized by current electrolysis with a current density of 0°02 to 0.5 A/d''C in a dehydration bath solution.Surface oxidation of Zr and Hf and their alloys. Film removal method, (8) Zr:13- and Hf having oxide films, and alloys thereof. Ammonium fluoride concentration 1i: 0.1 to 0.5 mol. Ammonium nitrate concentration: 1/10 of ammonium fluoride.
Concentrations from 0 to 115. Hydrogen peroxide concentration: 1/10 to 1/ of ammonium fluoride
Concentration of 2. And, by adding one or more of ammonium salt, sodium salt, and potassium salt of citric acid, oxalic acid, or tartaric acid, PF (5 to 6) was maintained, and ultrasonic vibration Qfl was applied. ?Zk in finished liquid, tJt, flow density: 0°02~・0°5 A/LJ
Zr-yo, which is characterized by the completion of five corners in Konoichi? Yohi Hfil[;
Knee; E: Method.