JPS58153800A - Electrolytic polishing treatment of aluminum or aluminum alloy - Google Patents

Abstract

PURPOSE:To prevent a blooming in alumite treatment, by a method wherein aluminum or the like is electrolytically polished in a polishing bath containing Na2CO3 and Na3PO4 under definite voltage and thereafter held therein under specific voltage or less after the voltage is lowered within a short time. CONSTITUTION:A product to be treated comprising aluminum or an aluminum alloy is immersed in an electrolytic polishing aqueous solution containing about 10-20% Na2CO3 and about 2.5-7.5% Na3PO4 and subjected to electrolytic polishing under usual conditions wherein voltage is constantly held to about 15V, the temp. of the electrolytic polishing solution is adjusted to a range of 70- 90 deg.C and a treating time is about 4min while said aqueous solution is shaken. Subsequently, voltage is lowered to 2V or less within a short time of about several sec-30sec and, under lowered voltage of 2V or less, current supply is carried out for about 5-60sec. The product to be treated which is pulled up after current supply is stopped and subjected to the aforementioned polishing treatment has a gloss surface and causes no blooming perfectly on the oxidized film surface thereof subjected to succeeding anodization treatment.

Description

[Detailed Description of the Invention] Conventionally, when using phosphoric acid or a bath solution containing phosphoric acid dissolved in water as an electrolytic bath for electrolytic polishing treatment of aluminum or aluminum alloy, it is dangerous and insufficient, especially when handling concentrated sulfuric acid. The work is difficult and requires careful attention, and the phosphoric acid is relatively expensive. The loss is large.In order to prevent this, a relatively inexpensive and non-hazardous Na200
．． It is conceivable to use an electrolytic bath solution that is usually used for electrolytic polishing treatment called the Brital method, which contains Nato 0x and NJP 04, but according to the so-called Prital method using this, Nato 0x and Na1PO, In an electrolytic bath dissolved in water, at a constant voltage of about 10 to 30 V, the temperature of the solution is maintained at 70 to 90°C, and the solution is electrolytically polished for the required time while being oscillated, and then immediately pulled up. Although the above-mentioned disadvantages of electrolytic baths using sulfuric acid and phosphoric acid are eliminated, the surface of the electrolytically polished aluminum or aluminum alloy is broken down and an extremely thin transparent oxide film is deposited, which is then subjected to alumite treatment. After sealing, it looks like powder is floating on the alumite film. A phenomenon commonly known as ``powdering'' appears strongly. However, after the electrolytic polishing process, a step is required to remove the thin oxide film that has adhered by immersing it in a film removing solution.

The present invention is directed to this Na! This provides an electrolytic polishing treatment method that does not cause the dusting phenomenon by using an electrolytic bath consisting of Na, 00.003, Na, 00.00. and Na, P.O.
After performing electrolytic polishing while rocking the solution in a polishing bath containing a regular constant voltage at a temperature of 70 to 90"C, the voltage is reduced to a voltage of 2V or less for a short time. It is characterized in that it is first turned off and then raised at a voltage of 2V or less for about 5 to 60 seconds.

Next, embodiments of the present invention will be described.

Aluminum or aluminum alloy M workpiece for electrolytic polishing treatment, Na, 0.10-20% and Na, P
o, 2.5-7, aqueous solution for polishing Prytal Ps containing 5% c: i' Electrolytic polishing is performed for several minutes, for example, 4 minutes, while shaking and moving the solution at a temperature in the range of ~90"C. In the conventional method, the current is immediately stopped at this point and the workpiece is pulled up, but in the present invention, the above-mentioned After electrolytic polishing, the current is continued to be applied, and the voltage ISV is lowered to a voltage of 2V or lower in a short period of about 30 seconds (hereinafter referred to as the first step), and then the voltage is lowered to 2V or lower. from several seconds to 60 at a (constant) voltage of
After maintaining the energization for about seconds (hereinafter referred to as the second step), the energization is stopped and pulled up. Like this [this, first
The electrolytically polished workpiece subjected to the step and the second step had a glossy surface, and no powdering phenomenon was observed on the surface of the oxide film formed by the subsequent alumite treatment. It is similar to that which has been electrolytically polished than the conventional method.
0ri/! + chromic acid 209/l), the subsequent water washing treatment, and the equipment involved therein can be omitted.

An example of the above-mentioned treatment method of the present invention is shown in the accompanying drawings.

A constant voltage of 15V δ:1 is applied between A and B [in the process of raising the voltage, it usually takes 5 to 10 seconds to reach 15V.

Between B and 0, the time to hold the constant voltage of 15V is 4 minutes as described above, and between 0 and D, the time is 5 minutes in the first step described above.
From 15V to 2V in ~60 seconds. Between D and E, 2Vl is held for 10 to 30 seconds in the second step. This gave an electrolytic polishing treatment with surface gloss and no dusting.

As a result of many experiments, when mechanical polishing is performed for 4 minutes at a constant voltage other than 15V, for example 10V and soy, the time between 0 and D is preferably in the range of 5 to 60 seconds. , the holding time between D and E is preferably in the range of 5 to 60 seconds. Further, the period between 0 and D is preferably 6 to 30 seconds.

Furthermore, for comparison, if the second step is not performed,
The dusting phenomenon could not be avoided.

The reason why the voltage in the second step must be at a maximum of 2V is that the dusting phenomenon could not be prevented by applying current while keeping the voltage -E constant. The results show that the second step treatment is effective in preventing powder dusting.
I was introduced.

In addition, in the second step, a small voltage in the range of 2V to 0V can be freely selected, and as shown in the figure (1), a constant voltage of 2V or less (in addition to the case where this is maintained) is used.
It is also possible to gradually lower the voltage as shown in code (2).

Next, specific examples will be described.

Example 1 A129/7 was dissolved in an aqueous solution of 10% Na, 00s, 7.5% Na, Po, and in a bath maintained at 80°C, a stainless steel plate was connected to the cathode and aluminum or aluminum alloy was connected to the anode, After applying electricity for 4 minutes while oscillating at a constant voltage of 10 V DC, and polishing it with ysfdf, the voltage was reduced by 2 VJ for 6 seconds.
After being kept in a bath for seconds, the electricity was turned off, taken out and washed with water, and then placed in a solution of 15% H2So at 20°C at 1.6 A/
When alumite was applied with a current of am' and sealed with a 90"C nickel acetate solution, the powder was not cut.

Example 2 A129/7 was dissolved in an aqueous solution of Ha, 0.20%, Na, Po, 2.5%, and placed in Bath-2 maintained at 80°C, and a stainless steel plate was placed as the cathode #itr#A [The aluminum laminate or aluminum alloy was connected, and after 4 minutes of electricity with oscillating DC constant voltage of 30V and electropolishing, the voltage was lowered to 2V for 5 seconds, and then the voltage was lowered to 2V for another 30V.
After continuously lowering the current from 2V to Ov in the air over a period of seconds, it was pulled out and washed with water, and then heated to 20°C with 15% H, So
When alumite was anodized in a solution with a current of 1.6 A/am' and sealed with a nickel acetate solution at 90°C, the powder was not cut.

Example 5 A129/l was dissolved in a 45% aqueous solution of NalOo, 20%NalP, and a stainless steel plate was connected to the cathode and aluminum or aluminum alloy was connected to the anode in a bath maintained at 80°C. After energizing for 4 minutes while rocking the voltage and performing electrolytic polishing, the voltage was lowered to Ov for 50 seconds, and the energization was lowered.
It was held in the bath for 5 seconds, taken out and washed with water, and then placed in a 15% H, SO solution at 20°C at 1.6 A/
When alumite was applied with a current of am' and sealed with a nickel acetate solution at 90°C, the powder was not cut.

As described above, according to the present invention, electrolytic polishing of aluminum or aluminum alloy is performed using Na, 00.
After energizing at a constant voltage, the first step is to lower the voltage to 2V or less in a short period of time, and then hold it at 2V or less for an appropriate period of time before energizing. Since the second step treatment is performed, a good electrolytic polishing treatment is performed that does not cause dusting on the alumite-treated surface, and conventionally, it is possible to perform a good electrolytic polishing treatment that does not cause dusting on the alumite-treated surface. This has the advantage of being able to omit various equipment.

[Brief explanation of the drawing]

The drawings are process diagrams showing an embodiment of the method of the present invention. (11, +21...G-D voltage holding state patent applicant: Honda Motor Co., Ltd. Agent: Kin Kitamura - 2 others)

Claims (1)

[Claims] The aluminum or aluminum alloy to be treated is treated with Na,
001, Na, and P04, electrolytic polishing is performed while the solution is rocked at a constant voltage in the electrolytic bath temperature range of 70 to 90°C, and then the voltage is turned off for a short period of time. So 2v
1. A method for disintegrating and polishing aluminum or aluminum alloy, which comprises lowering the voltage to a voltage of 2V or less, then holding the voltage at 2V or less for about 5 to 60 seconds, and then raising it.