JPH0931662A - Blackening treatment of stainless steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously apply blackening treatment to many stainless steel parts to be treated with uniform quality by subjecting the plural stainless steel parts to be treated to blackening treatment while being kept to an equal potential with each other by making them electrically conductive via connecting members. SOLUTION: Ten paring-shaped parts 4 to be treated, e.g. made of SUS304 are hung to the wires 2 made of SUS304 as jigs bent into a U shape which are attached in such a manner that they are inserted through piercing holes 3 cut through a supporting board 1 made of stainless steel. A copper wire 5 is connected to the supporting board 1, anoxidized film is chemically formed on the surface of parts 4, and blackening treatment is executed. By this method, the problem that dispersion is generated in the reaction rates among plural stainless steel parts to be treated, and unevenness is formed in the blackening degree to generate defective products is eliminated even if they are simultaneously treated, and plural stainless steel parts to be treated can simultaneously be subjected to blackening treatment with a uniform color tone.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is capable of chemically blackening a large number of stainless steel parts to be treated at the same time with uniform quality, and is useful for preventing light reflection of metal members for optical parts such as optical isolators. The present invention relates to a blackening treatment method for stainless steel which is effective for use.

[0002]

2. Description of the Related Art
A treatment for producing an oxide film on a metal surface such as stainless steel to blacken it is often performed. This blackening is performed for the purpose of suppressing the reflection of light from a metal member used for an optical component such as an optical isolator (Japanese Patent Application No. 7-71).
No. 361), and the purpose is to enhance the heat radiation ability of the surface of the cathode ray tube shadow mask (Japanese Patent Publication No. 61-67754).
Reference).

As a method of chemically blackening stainless steel material, there are a sulfurization oxidation method, an acid oxidation method, an alkali oxidation method and the like. Among them, the alkali oxidation method is often used because a more stable black color can be obtained. ing. In this alkaline oxidation method, for example, by immersing a stainless steel material in a mixed solution of boiling caustic soda and potassium nitrate for an appropriate period of time, a ferrosoferric oxide film is formed on the surface of the stainless steel to blacken it.

However, although the above-mentioned alkaline oxidation method is capable of high-quality blackening treatment, when a plurality of parts to be treated are simultaneously dipped in the same treatment liquid and treated, a treatment variation occurs between the components, There is a problem in that rejected products occur because color unevenness occurs between parts and uniform blackening is not performed, and improvement of this point has been desired.

The present invention has been made in view of the above circumstances.
An object of the present invention is to provide a blackening treatment method for stainless steel, which is capable of simultaneously blackening a large number of stainless steel parts to be treated with uniform quality.

[0006]

Means for Solving the Problems and Modes for Carrying Out the Invention As a result of intensive studies to achieve the above object, the present inventor has produced an oxide film chemically on the surface of stainless steel,
In the process of blackening, connecting a plurality of stainless steel parts to be processed to a connecting member made of an electrically conductive material,
A plurality of stainless steel parts are subjected to blackening treatment while being kept at an equipotential through the connecting member, and more preferably, blackening treatment is performed while the stainless steel to be treated and the entire connecting member are grounded. It has been found that the stainless steel parts to be treated can be simultaneously immersed in the same treatment liquid for blackening treatment with uniform quality.

That is, in the above-described conventional blackening treatment step, the stainless steel parts to be treated are electrically insulated from each other, the steel material is charged as the oxidation reaction progresses, and the reaction speed varies depending on each part. Therefore, when one part reacts to an appropriate color, the other parts still do not react sufficiently.

On the other hand, the inventor of the present invention, by connecting a plurality of parts to be processed with an electrically conductive material to make them equipotential, the reaction of all parts proceeds at the same speed, and thus the reaction speed It was found that the reaction can be terminated at the same time by aligning, the rejected product due to insufficient reaction or excessive reaction is eliminated, and blackened stainless steel parts can be obtained with a uniform color tone. It was the eggplant.

Therefore, according to the present invention, a plurality of stainless steel parts to be treated are connected to a connecting member made of an electrically conductive material in a method of chemically producing an oxide film on the surface of stainless steel to perform blackening treatment, There is provided a method for blackening stainless steel, characterized in that these stainless steel parts are blackened in a state in which they can be electrically connected to each other through the connecting member and are kept at an equal potential.

The present invention will be described in more detail below. In the method for blackening a stainless steel of the present invention, a plurality of objects to be treated are formed in the step of chemically forming an oxide film on the surface of the stainless steel and performing the blackening treatment. The stainless steel parts are electrically connected to each other and the blackening treatment is performed in a state where the stainless steel parts are kept at the same potential.

Here, the type of stainless steel may be any of ferrite type, martensite type and austenite type, and its alloying component is Fe--Co type,
Examples include Fe-Cr-based and Fe-Ni-Cr-based materials, and Fe-Ni-Cr-based materials are particularly preferably used. The shape, size, etc. of the stainless steel part can be appropriately selected, but in the present invention, Ni is 8 to 10.5.
%, Cr is 18 to 20% by weight, and the balance is iron. It is effectively used for blackening treatment of a holder for holding an optical component used for an optical isolator.

As a method of chemically forming an oxide film on the surface of stainless steel to perform blackening treatment, an ordinary method can be adopted, and examples thereof include a sulfidation oxidation method, an acid oxidation method and an alkali oxidation method. However, the alkaline oxidation method is preferable because a more stable black color can be obtained. The treatment liquid used in this alkaline oxidation method may have a known composition, for example, a treatment liquid containing caustic soda and potassium nitrate, to which a dichromate is further added if necessary, caustic soda, sulfate and lead peroxide. , A treatment liquid containing ferric hydroxide, etc., and commercially available products can be used. Examples of such commercially available products include stainless steel blackening agent H-540 manufactured by Nippon Surface Chemical Co., Ltd.

As the conditions for performing the treatment using the blackening treatment liquid, known ordinary conditions depending on the treatment liquid can be adopted.

In the present invention, a stainless steel part is immersed in the above-mentioned chemical blackening treatment solution and treated by a conventional method,
An oxide film is formed on the surface to turn black, but in this case, stainless steel parts to be treated are electrically connected to each other via a connecting member made of an electrically conductive material,
Thereby, the processing is performed while keeping each component at the same potential.

The material of the connecting member is not particularly limited as long as it is electrically conductive, but a metal such as stainless steel or copper is usually used. Also, the mode of connecting a plurality of stainless steel parts using this connecting member is not limited, but by forming a jig for supporting a large number of parts from metal, parts can be electrically connected to each other via this jig. A method of conducting can be adopted.

Further, it is preferable that the above-mentioned parts and connecting members are connected to the ground as a whole by using a wire such as a copper wire or the like, which can prevent electrification which delays the oxidation reaction rate, so that the oxidation reaction occurs during the reaction. The blackening treatment can be performed by satisfactorily promoting the oxidation reaction without blunting.

[0017]

According to the method for blackening a stainless steel of the present invention, even if a plurality of stainless steel parts to be treated are processed at the same time, the reaction speed between the parts varies and the blackening degree becomes uneven. There is no problem that rejected products occur, and it is possible to blacken multiple stainless steel parts to be processed at the same time with a uniform color tone.Reflecting light from metal members used for optical parts such as optical isolators. It can be used for applications such as suppressing

[0018]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Examples and Comparative Examples] As the stainless steel parts to be treated, ring-shaped ones made of SUS304 and having an outer diameter of 2.8 mm, an inner diameter of 1.5 mm and a thickness of 1.0 mm were used. It was mounted on the jig shown in FIG. 1 and processed.

Here, the jig shown in FIG.
A U-shaped 304 wire 2 is inserted into an insertion hole 3 formed in the support plate 1 and attached.
The parts 4 can be processed by suspending the parts 4 to be processed on the wire 2. In this case, in the comparative example, the support plate 1 formed of fluororesin (PTFE) was used. Therefore, in the comparative example, the parts suspended on the same U-shaped wire are electrically connected to each other through the wire, but are not electrically connected to other parts. On the other hand, in the examples, stainless steel was used as the support plate 1.
Therefore, in the embodiment, all parts are electrically connected through the support plate and the wire. In the example, a copper wire was attached to the support plate 1 and grounded as shown.

Then, after the parts were placed on the jig shown in FIG. 1, the following three steps of degreasing, pretreatment and blackening were performed. (1) Degreasing step: Immersed in a 2-fold dilution of Super Rabi Clean SR-AC (manufactured by Interplan) for 1 hour. (2) Pretreatment step: Immersed in a 3-fold diluted solution of concentrated hydrochloric acid for 1 minute. (3) Blackening treatment process: Stainless blackening agent H-540
It was immersed for 5 minutes at the boiling point (manufactured by Nippon Surface Chemical Co., Ltd.).

The blackening results of the above-mentioned embodiment and comparative example are shown in FIGS. 2 and 3 show the state of the wire of the jig after the blackening treatment in Examples and Comparative Examples, respectively, and all 10 of the wires in the example of FIG. 2 are blackened to a uniform shade. However, the wire of the comparative example of FIG. 3, N
o. No. 5 was not blackened, and there were blackened portions and non-blackened portions.

Further, as a result of visually observing the blackened parts, in the example, there is no unevenness in color tone among the 10 parts, and the black color having the same color tone is favorably and uniformly blackened. On the other hand, in the comparative example, there is unevenness in the hue between the parts, and in particular, the above No. 3, No. The color of the part attached to the wire of No. 5 was light, and it was determined to be defective.

In the examples, when the case of being grounded and the case of not being grounded are compared, a good blackening treatment was carried out in 5 minutes when grounded.
Without grounding, it took 8 minutes to achieve the same degree of blackening.

Reference photographs 1 and 2 show this, and are micrographs showing a degree of blackening when treated with the above-mentioned stainless blackening agent for 8 minutes at a magnification of 100 times. Reference photograph 1 is grounded, It can be seen that Reference Photo 2 is not grounded, and the grounded one is darker.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a jig used in the blackening treatment method of the present invention.

FIG. 2 is a front view showing a blackened state of the wire of the jig after the treatment in the example.

FIG. 3 is a front view showing a blackened state of a wire of a jig after processing in a comparative example.

[Explanation of symbols]

 1 Support plate 2 Wire 3 Insertion hole 4 Stainless steel parts 5 Copper wire

Claims (3)

[Claims] 1. A method of chemically producing an oxide film on a surface of stainless steel for blackening treatment, wherein a plurality of stainless steel parts to be treated are connected to a connecting member made of an electrically conductive material, and these stainless steel parts are connected. A blackening treatment method for stainless steel, characterized in that the blackening treatment is carried out in a state where they are electrically conductive with each other through the connecting member and kept at an equal potential. 2. The blackening treatment method according to claim 1, wherein the blackening treatment is carried out while the stainless steel part to be treated and the connecting member are grounded. 3. The blackening treatment method according to claim 1, wherein the stainless steel part to be treated is blackened by an alkali oxidation method.