DE2431793A1 - TREATMENT METHODS OF THE SURFACE OF ALUMINUM OR ALUMINUM ALLOY - Google Patents

Description

DR.-ING. G. RIEBLING

My sign

K 305-14 / ΙΥΙθ

Please repeat in the answer

your message from 899 Lindau (Lake Constance)

Rennerle 10 P.O. Box 3160

June 27, 1974

Kansai Paint Company, Limited

365, Kanzaki, Amagasaki-shi, Hyogo-ken, Japan

Treatment method of the surface of Aluminum or aluminum alloy

This invention relates to a treatment method of Surface of aluminum or aluminum alloy, in particular a method of treating the surface of Aluminum or aluminum alloy that has a formed on it Has boehmite layer.

409885/0941

The surface of aluminum or aluminum alloy is chemically active / and sensitive to corrosion with acids and alkalis. Accordingly, various methods have heretofore been proposed to reduce the activity of the surface of aluminum or aluminum alloy and to improve its corrosion resistance. One such method is known as boehmite treatment, by which aluminum or aluminum alloy is brought into contact with hot water or steam, whether or not containing ammonia or amines, to form an aluminum oxide layer on the surface of the aluminum or aluminum alloy predominantly from. Al ₂ O ₃ .nH ₂ 0 consists wherein η is usually an integer of 1 to 3 Unlike other processes such as anodic oxidation process in which acid such as sulfuric acid is used to form an aluminum oxide film, the boehmite treatment process which does not use acid is very advantageous for industrial operations because it uses acid causes corrosion in the equipment during the anodic oxidation process, the resulting wastewater includes pollution problems and removal of the pollution requires further treatment which is expensive. Although the boehmite treatment process is completely free from these drawbacks, the thickness is that obtained by this process

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on the surface of aluminum or aluminum alloy -formed aluminum oxide layer limited to about 1.0 μ and the alumina layer is unsatisfactory in hardness and. dar structure. Thus the boehmite treatment other processes that use acid, inferior in their ability, to aluminum or aluminum alloy to give excellent corrosion resistance.

A A ^u fgabe this invention is to eliminate the above Nachteila the conventional boehmite treatment process.

Another object of this invention is to provide a Treatment method of the surface of aluminum or aluminum alloy to provide which the corrosion resistance of aluminum or aluminum alloy having a boehmite layer formed thereon.

Other objects of this invention will become apparent from the following description.

The objects of this invention can be achieved by a method that includes the operations of touching Aluminum or aluminum alloy with hot water or steam containing or not containing ammonia or amines,

409885/09 / »1 - 4 -

to form an aluminum oxide layer thereon and that Carrying out electrolysis using the resultant aluminum or aluminum alloy as the Electrode in an aqueous solution of a water-soluble salt of at least one oxyacid selected from Group consisting of silica, boric acid, phosphoric acid, lYlolybdic acid, vanadic acid, permanganic acid, and stannic acid Tungstic acid.

Our research has shown the following results:

(1) When aluminum or aluminum alloy of boehmite treatment is subjected to electrolysis using the resulting aluminum or aluminum alloy as the electrode in an aqueous solution of water-soluble salt of at least one of the above Oxy acids are followed by the dissociation of the oxy acid salt in the aqueous solution The resulting oxyacid anions are adsorbed by the surface of the aluminum or aluminum alloy, whereupon they release their charges to react with the aluminum oxide layer and thereby form a new layer.

(2) Compared with that by the boehmite treatment only

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If the aluminum oxide layer was applied, it was usually the same as that obtained above new layer a considerably greater thickness, improved Toughness and fine structure and is therefore a lot more corrosion resistant than the aluminum oxide layer alone.

According to the present invention, it is essential to carry out electrolysis using boehmite layer-bearing aluminum or aluminum alloy as the electrode in an aqueous solution of water-soluble salt of at least one oxy acid selected from the group consisting of silicic acid, boric acid, phosphoric acid, permanganic acid, vanadic acid , UJoIf ramic acid, hilolybdic acid and stannic acid. The water-soluble oxyacid salts to be used include various salts of the above oxyacids with monovalent to trivalent metals, ammonia or organic amines. The silicates include orthosilicates, tetra-silicates and disilicates and the like polysilicates. Examples thereof are sodium orthosilicate, potassium orthosilicate, lithium orthosilicate, sodium metasilicate, potassium metasilicate, lithium metasilicate, lithium pentasilicate, barium silicate, ammonium silicate, tetramethanolammonium silicate, triethynolammonium silicate, etc. The borates, borate borate oxides and additive products include borate borates, tetraborates, tetraborates, tetramorates. Examples are lithium laboratoryate (LiBO ₂ ),

409885/0941

-B-

Potassium metaborate (KBO ₉ ), sodium mataborate (NaBO ₉ ), ammonium mataborate, lithium tetraborate (Li ₉ B-JO _7. 5H ₉ O), potassium tetraborate, sodium tetraborate, ammonium tetraborate / ~ (ΝΗ _Δ ) ₉ Β, 0 ₇ .4Η ₉ 0 7 »calcium metaborate / ~ Ca (BO ₉ ) .-, .2H ₉ O 7» sodium pentaborate (Na ₀ B. _n 0 ,,. 10H ₀ O)> sodium perborate

ZlUlD Δ

(NaBO ₀ .H ₀ O ₀ .3H _o 0), sodium borate / hydrogen peroxide addition product (NaBO ₂ -H ₂ O ₂ ), sodium borate (NaH ₂ BO ₂ -HCOOH.2H ₂ O), ammonium borate / ~ (ΝΗ _Λ ) ΗΒ. O ₇ . 3H ₉ O ~ J _f ate.

The phosphates include orthophosphates, pyrophosphates and polymataphosphates. Examples are monobasic potassium phosphates (KH ₂ PO ₄ ), sodium pyrophosphate (Na ₄ P ₂ O ₇ ), sodium metaphosphate (NaPO "), aluminum hydrophosphate /""Al (H 1 PO,.), 7 etc. The uanadates include orthov / anadate , ITIetav / anadate untJ Pyrovanadate. Examples are lithium _{orthovanadate (Li 3} UO ₄ ), sodium orthovanadate (Na ₃ UO ₄ ), lithium meta anadate (LiUO ₃ .2H ₂ O), sodium meta anadate (NaUO ₃ ), potassium _{meta anadate (KUO 3} ), ammonium meta / anadate (NH ₄ UO ₃ ) or / ~ (NH ₄ ) ₄ U ₄ 0 ₁₂ _7, sodium pyrovanadate (Ne ₂ U ₂ O ₇ ), etc .. The uiolframates include orthoujolframate, lüetau / olframate, parauol ramate, pentatuol ramate, and heptauiolframate. Phosphorus sulfate, boron sulfate, and the like, complex salts can also be used. Examples are Lithiumiuolf ramat (Li ₉ UIO ₇ ,), Sodium uuolf ramate (NaUIO ^ .2H _o 0), Potassium tungstate (K ₂ IIIO ₄ ), Bariumuiolframat (BaIlIO ₄ ),

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Calcium iuol ramate (CaIlJO ₄ ), strontium _{iuolframate 4}

. Sodium metauolframate (Na ₂ III ₄ O ₁₃ ), potassium _{metauolframate (K 2} Ui ₄ O ₁₃ -SH ₂ O), sodium _{paraiuolframate (Na 6} UJ ₇ O ₂₄ ), ammonium pentaujalframate / "(NH ₄ I ₄ UJ ₅ O _{17 .5H 2} 0__7 "Ammonium heptauiolframate /" (NH ₄ JgUJ ₇ O ₂₄ .6H ₂ O _- J? Sodium phosphorus / olframate (2Na ₂ O. P ₂ O ₅ .12UJO ₃ .18H ₂ O), barium boron wo If ramat (2Ba0.Br, 0 ".9UJ0" .18H ₇ 0), etc .. Examples of permanganates !! are lithium permanganate (LiITInO ₄ ), sodium permanganate (NaMnO ₄ .3H ₂ O), potassium permanganate (KIIiInO ₄ ), ammonium parmanganate / "(NH ₄ ) ( lfLn0 ₄ _7> calcium permanganate / c "a (fflnO-) ₂ · 4Η ₂ 0_7> barium permanganate /""Ba (PfInO ₄ ) o7> magnesium permanganate / ~ ITIg (PfInO ₄ ) ₂ f6H ₂ 0_7» strontium permanganate / ~. Sr (plant ₎ ) ₂ .3H ₂ 0 ^ 7> etc .. The stannates include orthostannate and liletastannate. Examples are potassium orthostannate (K ₂ SnO ₃ .3H ₂ O), lithium _{orthostannate (Li 2} SnO ₃ .3H ₂ O), sodium _{orthostannate (Na 3} SnO ₃ .3H ₂ O), plant stsnnate, calcium stannate, lead stannate, ammonium stannate, potassium metastannate (K ₂ O.5SnO ₂ .4H ₂ O), sodium metastannate _{(Na 2 O.5SnP 2} . 8H ₂ O) etc .. Examples of fflolybdates are orthomolybdates, pftetamolybdates and paramolybdates. More specific examples are lithium _{molybdate (Li 2} PfIoO ₄ ), sodium molybdate, potassium molybdate (K ₂ IIIoO ₄ ), ammonium molybdate ^4H 2 ° -7 »triethylamine molybdate etc.

A09885 / 09A1

Among these oxy-acid salts are those of alkali metals preferred, which generally have high water solubilities exhibit. Among the oxyacid salts listed above It is preferable to use silicates because they are economical and readily available. According to this invention These oxyacid salts are used individually or in a mixture used together.

The concentration of such oxy acid salt in its aqueous Solution is usually about 0.1% by weight to saturation, preferably about 1.0% by weight to saturation, although it is variable with the kind of oxy acid salt.

In the present invention, water-soluble salts of chromic acid can be used together with the above-mentioned oxy acid salts, thereby further improving the anti-corrosive property of the resulting coating. Such chromate is used in an amount of about 0 to 50% by weight based on the oxy acid salt. Examples of chromates are lithium chromate (Li ₂ CrO .2H ₂ O), sodium chromate (Na ₂ CrO ₄ .10H ₂ O), potassium chromate (K ₂ CrO.), Ammonium chromate £ "(NH Λ ₂ ^Cr 0 ¹ ^ T \ calcium chromate (CaCrO..2H ₂ O) and strontium chromate (SrCrO,).

To be coated by the method of this invention

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Aluminum alloys include, for example, Al-Si, Al-Mg, Al-Mn or Al-Si-Mg. In the present invention, that can Aluminum or the aluminum alloys are commonly used as substrates in various shapes will.

To carry out the present method, the aluminum or aluminum alloy serving as the substrate is used Subjected to degreasing and etching processes. The degreasing is carried out by conventional methods such as dipping the aluminum or aluminum alloy in Acid such as nitric acid, sulfuric acid at room temperature for 5 to 60 minutes. During the etching process, the disfigurement and the spontaneously formed Oxide film is removed from the aluminum or aluminum alloy by conventional methods such as dipping of aluminum or aluminum alloy in alkali solution.

The aluminum or aluminum alloy thus pretreated is then subjected to the boehmite treatment in a conventional manner subjected. The beohmite treatment is usually carried out by touching the aluminum or the Aluminum alloy with hot Ujasser or steam that Contains ammonia or amines or not. Examples of the

409885/0941 " ¹⁰ "

-AQ-

Usable amines are hflonoethanolamine, diethanolamine,
Triethanolamine, dimethylethanolamine and the like. Water-soluble amines. In general, about 0.1 to 5 parts by weight of amine or ammonia are used per 100 parts by weight of water. The aluminum or aluminum alloy is usually left under atmospheric pressure for about 5 to 60 hours
increased pressure in contact with hot water or steam
held. The temperature of hot Illasser to be used is usually in the range of 60 C to the boiling point, preferably the boiling point and the steam in the range of 100 to 200 ° C, preferably 120 to 18O ⁰ C. Such
Touching is carried out by previously used methods, such as immersion or spraying.

After boehmite treatment, electrolysis is carried out as follows:

The aluminum or aluminum alloy and another electrically conductive material used as an electrode
are immersed in aqueous solution of the above-mentioned oxy acid salt, and electric current is passed between the
Electrodes applied. The electric current is either
Direct current or alternating current. If direct current is used, the aluminum or aluminum alloy is said to be the
Be anode and if alternating current is used, that can

409885/094 1 - 11 -

2A31793

Aluminum or the aluminum alloy can be used as either an anode or a cathode. The advantageous one The voltage range is from 5 to 300 UoIt for direct current or from 5 to 200 WoIt for alternating current. The electric current is applied for more than 5 seconds. The temperature of the electrolytic solution is usually in the area between the solidification point of the salt the oxyacid and the boiling point of the solution, preferably in the range from 20 to 60 ° C.

According to this invention, the electrolytic process can be repeated two or more times with an aqueous solution of the same oxyacid salt or with aqueous solutions of different ones Oxy acid salts are carried out. For example, electrolysis is done with an aqueous. Solution of silicate performed and then with the same aqueous solution of silicate or first with an aqueous solution of silicate and then with an aqueous solution of another oxy acid salt. When the electrolysis is carried out repeatedly becomes, the obtained aluminum or aluminum alloy product gives higher corrosion resistance than when it only runs once. In addition, the electrolysis causes some U-water, U-hydrogen gas in the form to give up from bubbles. As a result, the formation of bubbles reduces the efficiency of the electrolytic process. if

409885/0941

however, the electrolysis can be carried out repeatedly the evolution of hydrogen gas is markedly reduced compared with the case where the electrolytic process is carried out only once, which improves the efficiency ensures.

After the electrolysis, the aluminum or the aluminum alloy becomes rinsed with water and dried, creating a thick coating of greater hardness and finer structure is formed. According to this invention, if desired, the dried product can be heated to a temperature of about 150 to 250 C can be heated further in order to increase the hardness of the coating.

The method of this invention will now be described in more detail with reference to Examples and Comparative Examples in which the percentages and parts, unless otherwise stated, are all based on weight. In the examples, aluminum plates serving as substrates were prepared and electrolytic operation was carried out according to the procedures given below. ·

409885/0941

Manufacture of substrate

A substrate was prepared by degreasing and etching an aluminum alloy plate measuring 70 mm in width, 150 mm in length and 2 mm in thickness (composed of 98.0 % aluminum, 0.45 % Si, 0.55 % IYIg and 1 % others; 3IS H 4100) according to the procedure given below:

(a) Immersion in 10% aqueous solution for 5 minutes uon nitric acid at room temperature.

(b) rinse in water.

(c) Immersion in 5 % aqueous solution of sodium hydroxide at 50 ° C. for 5 minutes.

(d) Rinse in water.

(β) Immersion in 10 % aqueous solution for 1 minute

uon nitric acid at room temperature. (f) rinsing in water.

Electrolytic process

In a plastic container with a dimension of 10 cm

3 width, 20 cm length and 15 cm depth became 2000 cm one Solution of an oxy acid salt and that serving as the anode Substrate was placed and a mild steel plate serving as the cathode was immersed in the solution at a distance

409885/0941

- 14 -

15 cm immersed to each other. Electrolytic process was at a liquid temperature υοη 25 C by Application of a fixed voltage carried out. That The substrate was then washed with water and dried.

In the following examples and comparison examples Acid resistance determined by CASS test according to 3IS H 8601. Alkali resistance was measured in terms of time (in Seconds), stopped for the occurrence of blistering when an N ^ aqueous solution υοη sodium hydroxide was applied dropwise to the treated sample.

• Example 1

An aluminum substrate made as described above was for boehmite treatment for 5 minutes in boiling, Immersed in deionized water, then rinsed with water and then in 20% aqueous solution of sodium silicate (Na “0.2SiCL ·) immersed to perform at the electrolysis specified voltage (direct current) for the specified, to be carried out in the period specified in Table 1 below, The aluminum substrate was then rinsed with water and dried at room temperature. The sat resistance of the thus treated aluminum substrate was measured with the result shown in Table 1.

409885/094 1

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Examples 2 to 4

Aluminum substrates were prepared in the same manner as in Example 1 dealt with except that electrolysis was carried out at the voltages and times shown in Table 1 became. The solidity of each of the thus treated aluminum substrates were compared with the one in Table 1 measured result.

Comparison example 1

An aluminum substrate prepared as above was immersed in boiling, deionized for 5 minutes for boehmite treatment Submerged in water, followed by rinsing with water and drying. The durability of the treated substrate is listed in Table 1.

Comparative Examples 2 and 3 Aluminum substrates prepared as above were in 20 % xqe

aqueous solution of sodium silicate (Na ₂ O.2SiO ₂ ) immersed without carrying out boehmite treatment and electrolysis was carried out under the conditions listed in Table 1, followed by rinsing with water and drying. The resistance of each of the treated substrates

409885/0941

was measured with the result shown in Table 1.

Examples 5 and 6

After electrolysis was carried out in the same manner as in Example 1 except that the conditions were otherwise set as shown below, aluminum substrates were rinsed with water and then dried. The substrates were further heated to 200 ⁰ C. The stability of each of the substrates thus treated is given in Table 1.

Comparison example 4

An aluminum substrate treated as above became boehmite treatment Immersed in boiling deionized water for 5 minutes, followed by rinsing with water, drying and then heating to 200 C followed. The sec ** e resistance of the treated substrate is listed in Table 1.

l / comparison examples 5 and 6

Aluminum substrates prepared as described above were immersed in a 20% aqueous solution of sodium silicate (Na _{2 O.2SiO 2} ) to undergo electrolysis under the conditions shown in the following table

409885/0941 - 17 -

1 to be carried out. The aluminum substrates were then rinsed with water, dried and then heated to 200 ° C. for 1 hour. D ¹ B Acid resistance of each of the aluminum substrates thus treated
was measured with the result shown in Table 1.

- 18 -

409885/0941

O CD OO

α> cn

-Ν »

O CD

electrolysis
tension
(W) conditions
Time Table 1 Hours) alkali
resistance 40 (sec) 9 (lake) 40 120 Acid resistance
(Rating number) 9 95 example 1 80 600 4 (hours) 8 ( 9.5 110 2 80 120 9.5 9.5 132 3 - 600 9.5 6th 150 4th 40 _ 9.5 6th 12th Comparative
example 1 80 120 9.5 6th 21 2 40 600 8th 9 25th 3 80 120 8th 9.5 115 Example 5 _ 120 8th 6th 160 6th 40 _ 9.5 6th 11 Comparison
example 4 80 120 9.8 7th 20th 5 120 <
8th 26th 6th 8th 8th

VO

CD

ro CO

CO CaJ

Examples 7 and 8

Aluminum substrates produced as described above were immersed for 15 minutes in a boiling solution consisting of 0.5 part diethfnolamine and 100 parts deionized water, then rinsed with water and then immersed in 20% aqueous solution of potassium silicate (K ₂ 0.3SiO ₂ ) to carry out electrolysis under the conditions shown in Table 2 below. The aluminum substrates were then rinsed with water and dried at room temperature. The acid resistance of each of the thus treated aluminum substrates was measured with the result shown in Table 2.

Comparison example 7 '

An aluminum substrate prepared as above was placed in sine boiling solution consisting of 0.5 parts diethanolamine and 100 parts deionized water, immersed for 15 minutes, followed by rinsing with water and drying at room temperature. The acid resistance the treated Substrate is listed in Table 2.

- 20 409885/0941

Table 2

CD CO OO OO

example

Comparative example 7

Eltrolysis conditions voltage (\ l) time (see)

4G (direct current) 80 (direct current) acid resistance
(Contribution number)

4 (hours) B (hours)

9.8
10

8.5

9.5
9.5

K)

GJ

CD

BgJspisle 9 to 15

Aluminum substrate B were prepared in the same way Example 1 dealt with, except that Dxysäuresalze in the amount given in Table 3 were used instead of sodium silicate. The acid resistance of everyone the thus treated substrates were determined with the result given in the table.

409885/0941

- 22 -

co OO OO cn

co

Type the oxyacid salt Tab Ils 3 3 time
(sac) Acid Resistant
• (construction / type number) Hours) at
game Conc
tration 120 4 (hours) 8 ( 9.5 No. Sodium metabroate (%) ElektrolysB-
bad conditions 120 9.5 9.5 9 Sodium naphosphate 5, Q Tension
(M) ' 120 9.5 9.5 10 Potassium parmanganate 3.0 100 120 9.5 9.0 11 Ammonium metauanadate 2.0 60 120 9.5 9.0 12th Potassium uyolf ramat 1.5 60 120 9.5 9.3 13th Potassium molybdate 3.0 60 120 9.5 9.0 14th Potassium orthostannate 3.0 60 9.5. 15th 2.0 60 60

♦ ο

Example 16

For boehmite treatment, an aluminum substrate prepared as described above was immersed for 10 minutes in boiling, deionized water, then rinsed with water and then immersed in a solution, prepared by adding 10 parts of 55% aqueous solution of sodium silicate (Na "O. 2SiO _? ) And 3 parts of potassium _{orthomolybdate (K 2} IYIoO.) To 100 parts of deionized water to carry out electrolysis by applying direct current with 50 UoIt for 60 seconds. The substrate was then removed from the solution, rinsed with Illasser and then dried at room temperature.

Example 17

An aluminum substrate prepared from above was immersed for 10 minutes in a boiling solution of 0.3 part diethanolamine in 100 parts deionized water, then rinsed with water and then immersed in an aqueous solution, prepared by adding 10 parts 55 / Giger aqueous solution of sodium silicate and 0.5 part of potassium _{metavanadate (KUO 2} ) to 150 parts of deionized water to carry out electrolysis by applying direct current with 30 UoIt for 3 minutes. The substrate was then

409885/0941 _ ₂₄ _

- J24 -

taken out of solution and rinsed with water. After this Drying, the substrate was heated to 180 ° C for 30 minutes.

Example 18

An aluminum substrate subjected to boehmite treatment in the same way as in Example 16 was immersed in a solution prepared by adding 15 parts of 40% aqueous solution of sodium silicate (Na ₂ O.2SiO ₂ ) and 2 parts of potassium stannate (K ₂ SnO ₃ .3H ₂ O) to 150 parts of deionized water to carry out electrolysis by applying direct current at 30 UoIt for 30 minutes. The substrate was then removed from the solution and rinsed with water. After drying, the substrate was heated for 30 minutes at 18O ⁰ C.

The acid resistance of each of the treated aluminum substrates obtained in Examples 16 to 18 was found to be measured according to the result listed in Table 4 below.

409885/0941 " ²⁵ "

Table 4

Acid resistance (rating number)

4 (hours) 8 (hours)

Example 16 9.5 9

17 9.5 9

18 9.5 9

Examples 19 to 21

Aluminum subsiJates are produced in the same way as in Treated Example 16, except that given in Table 5 oxyacid salts instead of sodium silicate and Potassium orthomolybdate were used. The acid resistance of each of the thus treated substrates was measured with determined according to the result given in Table 5.

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Tabel

Example of oxy acid salts - concentration - electrolysis - acid resistance play tration condition (rating number)

^{Nr #} (parts per _{annunn q} _ ₇ _ _lt

1r \ n τ _ s ι _ ϋθα I] IIU [IU /.a XL · uu ι e ι ie r .. \

UJasser) ^ *

Time ^ ₄ ( _hours ) ₈ (hours)

19th

20th

21

{Potassium metaborate Sodium metaphosphate Γ potassium molybdate (^ potassium permanganate Γ ammonium metav / anadate I ammonium thiolframate

1.5 1.5

60

60

60 120

120

9.5

9, θ

9.5

9.5

9.5

9.3

Example 22

An aluminum substrate prepared as described above was immersed in boiling, deionized water for 10 minutes, then rinsed with water, and then immersed in a 5% aqueous solution of sodium silicate (Na "0.2 SiO") to carry out electrolysis at 30 minutes. After rinsing with water, the substrate was immersed in 3% aqueous solution of sodium metaborate (Na ₇ BO ₉ ) to carry out electrolysis at 6Ü WoIt for 60 seconds. The substrate was then rinsed with water, then dried and heated at 160 ° C. for 30 minutes. Currents applied for electrolysis were direct current.

Example 23 to 25

Aluminum substrate was treated in the same manner as in Example 22 except that shown in Table 6 Oxy acid salts instead of sodium silicate and sodium metaborate were used. The corrosion resistance of each of those thus treated in Examples 22-25 Substrates were determined with the result given in Table 6.

409885 / 0.9 41 ~ ²⁸ ~

Table 6

At-

game _{1 # ElBktrolys}

Type of oxyacid salt

No.

2. Electrolysis

Acid resistance alkali

(Discharge number) consistently

8 age

(Hours) (hours) \ ^3ec )

CO CO CO

22nd

23

24 25

Sodium silicate (Na ₂ O.2SiO ₂ )

Sodium silicate (Na ₂ O.2SiO ₂ )

Calcium permanganate

Aluminum hydrophosphate

/ fr () 7

Sodium metaborate (NaBO ₂ )

Ammonium para

molybdate

Ζ ~ () 7

10

Potassium stannate (K ₂ SnO ₃ )

Potassium meta ujolf ramat 9.8

10

9.5

9.8

9.5

9.8

9.5

300

120

360

360

ro co

CD CO

Claims (12)

Claims QJ Treatment method of the surface υοη aluminum or aluminum alloy, characterized by the operations of contacting the aluminum or aluminum alloy with hot water or steam to form an aluminum oxide layer thereon and performing electrolysis using the resulting aluminum or aluminum alloy as the electrode in an aqueous solution of a water-soluble salt of at least one oxy acid selected from the group consisting of silicic acid, boric acid, phosphoric acid, molybdic acid, vanadic acid, permanganic acid, stannic acid and tungstic acid. 2. The method according to claim 1, characterized that the concentration of the water-soluble salt in the aqueous solution is in the range of 0.1 Weight - / ^ to saturation lies. 3. The method according to claim 2, characterized in that that concentration in dam area υοη 1.0 Geu / ichta-ji to saturation. 409885/0941 -30- 4. The method according to claim 1, characterized in that the water-soluble salt is at least one water-soluble salt of silica. 5. The method according to claim 1, characterized gekennzeichne.t that the water-soluble salt is at least one water-soluble salt of boric acid. 6. The method according to claim 1, characterized in that the water-soluble salt at least one water-soluble salt which is phosphoric acid. 7. The method according to claim 1, characterized in that the water-soluble salt is at least one water-soluble salt of I-molybdic acid. 8. The method according to claim 1, characterized in that the water-soluble salt is at least one water-soluble salt of vanadic acid .. 9. The method according to claim 1, characterized in that the water-soluble salt is at least one water-soluble salt of permanganic acid 409885/0941 - 31 - »31 - 10. V / experience according to claim 1, d a d u r c h "'' characterized in that the water-soluble salt is at least one water-soluble salt such as stannic acid. 11. The method according to claim 1, characterized characterized in that the water-soluble salt is at least one water-soluble salt of tungstic acid. 12. Aluminum or aluminum alloy, thereby characterized in that it is treated by the method claimed in claim 1. 409885/0941