JP3367092B2 - Method for producing antimicrobial stainless steel having wear resistance - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing antibacterial stainless steel having wear resistance used in various sanitary equipment, food processing equipment and the like.

[0002]

2. Description of the Related Art The refined net of a grain processing machine, which is a food processing equipment,
Since the polishing net is constantly subjected to an abrasion effect due to contact with grains, as a refined mesh, a rolled steel sheet of alloy steel having a surface hardness of 400 to 1300 HV by surface hardening treatment such as nitriding, carburizing and quenching, or carbonitriding and quenching, particularly resistant When abrasion resistance is required, 1000 to 1300 HV stainless steel is used.

By the way, since the grain refiner is a device for removing the outer coat of the grain by friction or grinding action, adhesion of bran (the outer coat separated from the grain) to the refined net is inevitable, and the refined net is Bacteria are easily proliferated by the adhesion of bran, but the white net has no antibacterial measures.

As an alloy steel having antibacterial properties, there is known stainless steel whose antibacterial properties are enhanced by the bactericidal effect of copper and / or silver which are antibacterial elements. However, when these stainless steels having antibacterial properties are used in the polishing cylinder, although the growth of bacteria due to the adhesion of bran can be suppressed, the surface hardness of the stainless steel is usually 150 to 200.
There was a problem that it was as low as HV and lacked in abrasion resistance.

It is also conceivable to subject the above stainless steel to a nitriding treatment for the purpose of improving wear resistance. In this case, the antibacterial element exposed on the surface of the stainless steel is buried in the nitride layer, and There is a problem that the antibacterial effect of steel is reduced.

[0006]

SUMMARY OF THE INVENTION In view of the above problems, the present invention has an antibacterial stainless steel having a high surface hardness, a high abrasion resistance, and an abrasion resistance that does not allow bacteria to propagate due to the bactericidal effect of the antibacterial element. A technical problem is to provide a method for manufacturing steel.

[0007]

In order to solve the above-mentioned problems, the present invention performs a first plasma treatment of stainless steel containing an antibacterial element in an atmosphere consisting of nitrogen and hydrogen, and then the stainless steel is subjected to argon and / or Alternatively, the technical means of performing the second plasma treatment in an atmosphere of hydrogen was taken.

The second plasma-treated stainless steel is preferably subjected to a third plasma treatment in an atmosphere of nitrogen and hydrogen.

[0009]

FIG. 1 shows an apparatus for carrying out the method of the present invention. Reference numeral 1 is a vacuum container, reference numeral 2 is a gas control device, reference numeral 3 is a plasma power source, and reference numeral 4 is a pressure regulating valve. Reference numeral 5 is a vacuum exhaust device, reference numeral 6 is antibacterial stainless steel containing an antibacterial element such as copper, and the stainless steel 6 is preliminarily processed into a shape according to the purpose of use.

In the first plasma treatment, the stainless steel 6 is placed on the placing table 7 in the vacuum container 1, and the gas control device 2 puts the mixed gas of nitrogen and hydrogen in the vacuum container 1 (10 to 90% of nitrogen). , The rest is hydrogen), and the pressure in the vacuum container 1 is adjusted to 3 to 5 by the pressure adjusting valve 4 and the vacuum exhaust device 5.
The pressure is reduced to Torr to make a vacuum. Then, by applying a DC voltage from the plasma power source 3 to the stainless steel 6, a glow discharge is generated in the vacuum container 1 and the stainless steel 6 is collided with nitrogen ions and hydrogen ions (A in FIG. 2). A nitride layer 8 is formed on the surface layer portion of 6 (B in FIG. 2). At this time, the copper exposed on the surface of the stainless steel 6 is buried in the nitride layer 8, and the stainless steel 6 has a high hardness (about 1200 HV) but does not exhibit antibacterial properties. The processing time is 1 to 48 hours, and the temperature in the vacuum container 1 is maintained at 400 to 600 ° C.

In the second plasma treatment, the gas in the vacuum chamber 1 is switched to argon and / or hydrogen, and 400 to 70 is used.
Sputtering is performed at 0 ° C. for 0.1 to 10 hours. The collision of argon ions and / or hydrogen ions with the nitride layer 8 causes iron ions in the nitride layer 8 to be released, and as the nitride layer 8 is gradually decomposed, the copper embedded in the nitride layer 8 is removed. Is exposed (C in FIG. 2), the stainless steel 6 has a high hardness (about 1000 HV) and is in a state exhibiting antibacterial properties.

Since the stainless steel 6 after the first and second plasma treatments has a high hardness and exhibits an antibacterial property due to the exposure of copper, it can be used as a white net of a grain mill, but the hardness is further increased. If you want to, after the second plasma treatment,
The gas in the vacuum container 1 was switched to a mixed gas consisting of nitrogen and hydrogen (nitrogen 10 to 90%, the rest being hydrogen), and 400
Stainless steel showing higher hardness and antibacterial properties is obtained by performing a third plasma treatment at a temperature of up to 600 ° C. for 0.5 to 5 hours to such an extent that copper is not buried in the formed nitride layer 8 (D in FIG. 2). Steel 6 can be obtained.

Further, the stainless steel 6 processed into a shape according to the purpose of use is subjected to a nitriding treatment to form a hardened layer on the surface layer portion of the stainless steel 6 to generate a residual compressive stress, so that fine particles generated at the time of processing can be obtained. It is possible to suppress the development of large cracks.

[0014]

[Effects of the Invention] After the first plasma treatment of stainless steel containing an antibacterial element in an atmosphere consisting of nitrogen and hydrogen,
By subjecting the stainless steel to the second plasma treatment in an atmosphere of argon and / or hydrogen, a nitride layer can be formed on the surface layer of the stainless steel with the antibacterial element exposed on the surface of the stainless steel. Therefore, it is possible to obtain a stainless steel having a high surface hardness, a high abrasion resistance, and a bactericidal effect of an antibacterial element, which does not allow bacteria to propagate.

When the second plasma-treated stainless steel is subjected to the third plasma treatment in an atmosphere of nitrogen and hydrogen, the stainless steel having a higher hardness can be obtained without losing the antibacterial property. be able to.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a plasma processing apparatus.

FIG. 2 is an explanatory diagram of a stainless steel surface state by plasma treatment.

[Explanation of symbols]

1 vacuum container 2 gas control device 3 Plasma power supply 4 Pressure control valve 5 Vacuum exhaust system 6 stainless steel 7 table 8 Nitride layer

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C23C 8/00-8/80 C23F 4/00 A01N 1/00-65/02 C22C 38/00

Claims (2)

(57) [Claims] 1. A stainless steel containing an antibacterial element is first plasma-treated in an atmosphere of nitrogen and hydrogen,
A method for producing an antibacterial stainless steel having abrasion resistance, which comprises subjecting the stainless steel to a second plasma treatment in an atmosphere of argon and / or hydrogen. 2. The antibacterial stainless steel having abrasion resistance according to claim 1, wherein the second plasma-treated stainless steel is subjected to a third plasma treatment in an atmosphere consisting of nitrogen and hydrogen. Manufacturing method.