JPH0578861A - Method for imparting sterilizing property and fungal resistance to appliance - Google Patents

Abstract

PURPOSE:To impart a sterilizing property and fungal resistance to an appliance by plating the appliance with Co and then further with Cr. CONSTITUTION:An appliance to be plated or the plated appliance is plated with Co or a Co-Ni eutectoid and then further with Cr. This plating with Co or a Co-Ni eutectoid is conducted by the conventional method. The appliance is made resistant to corrosion and wear in this way.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plating method for imparting sterilization and antifungal properties to equipment.

[0002]

2. Description of the Related Art In food processing machines and the like, it is desirable that the parts that come into direct contact with food are safe in terms of hygiene, and at the site, food products attached to instruments and devices are removed with hot water, steam, etc. We strive to prevent the attachment and reproduction (development) of various harmful bacteria that exist in nature as much as possible.

In addition, hospitals, public toilets, public baths, companies,
Appliances and equipment, etc., such as trains, buses, ships, etc. where unspecified number of people's hands can touch, such as hand-washing faucets, cooks,
It is necessary to take precautions for hygiene because bacteria and fungi may grow on valves, flush toilet levers, door knobs, and automobile handles. Therefore, it is necessary for hygiene and safety that the material used for the device itself has bactericidal properties and antifungal properties.

Also, kitchen knives, sinks, etc.
Similarly, sterilization and antifungal properties are required for surgical scalpels and containers as medical instruments, and also for drain pans in air conditioning equipment in hospitals and semiconductor manufacturing plants.

Here, silver or amalgamated mercury has been known as a metal having a strong bactericidal and antifungal property. However, these metals have very poor corrosion resistance to water and air, low hardness, and poor wear resistance. Moreover, since it is expensive, it cannot be used as an industrial material used in large amounts. Further, since mercury is harmful, its range of use is also limited.

Although Co alloys and Co platings have been conventionally known, since they have good corrosion resistance at high temperatures, they are used in heat-resistant, wear-resistant alloys, high speed steels, etc. where they are required. , For the purpose of sterilization and antifungal properties which are the objects of the present invention, food processing machines, kitchen knives as kitchen utensils, sinks, pans, frying pans, spoons, forks, surgical scalpels as medical instruments, containers, etc., Furthermore, equipment such as drain pans in air conditioning equipment at hospitals and semiconductor manufacturing plants, hospitals, public toilets, public baths, companies, trains, buses, ships, etc. For example, there is no example of use in faucets for hand washing, cocks, valves, flush toilet levers, door knobs, automobile handles, etc.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above problems of the prior art and enables mass production at a low price.
Another object of the present invention is to provide a device having excellent corrosion resistance and abrasion resistance, which has a strong bactericidal property and antifungal property.

[0008]

The above object of the present invention is to provide Co (cobalt) plating or Co.Ni (Co (Ni) plating) directly on an instrument which is an object to be plated or after the instrument which is an object to be plated is plated. Nickel) Eutectoid plating, Cr
It is solved by a method of imparting sterilizing property and antifungal property to a device by applying (chrome) plating.

Instruments requiring sterilization or antifungal properties include food processing machines, household nail clippers, scissors, kitchen knives, sinks, surgical scalpels as medical instruments, containers, etc. And drain pans in air conditioning equipment at semiconductor manufacturing plants, hospitals, public toilets, public baths, companies,
Appliances and equipment, etc., such as trains, buses, ships, etc. where unspecified number of people's hands can touch, such as hand-washing faucets, cooks,
Valves, flush toilet levers, door knobs, automobile handles, and other devices that require hygiene, that is, equipment and devices that require cleanliness.

The method of plating the device with Co is a known method. As the electroplating method, for example, sulfuric acid C
o 240g / l, CoCl 45g / l, Boric acid 30g /
1 bath, with a bath temperature of 40 to 50 ° C. and a cathode current density of 2 to 6
There is a method of plating with A / dm ² . Further, for example, in a bath containing 500 g / l of sulfuric acid Co and 20 g / l of Co chloride, at a bath temperature of 18 to 25 ° C., a cathode current density of 3 to 17 A / dm ^2.
Alternatively, a method of plating may be used. Examples of the chemical plating method include sulfuric acid Co 0.05 mol / l, NaH ₂ PO
₂ 0.2 mol / l, Na ₂ C ₄ H ₄ O ₆ 0.5 mol
/ L, (NH ₄ ) ₂ SO ₄ 0.5 mol / l to NH ₄ O
There is a method in which the pH is adjusted to 10.2 with H and the temperature is 80 ° C.

In the case where an electroplating method is used for Co plating an instrument, the instrument to be plated must naturally be an electric conductor. That is, in the case of electric conductors such as steel, copper, aluminum, zinc and the like and alloys thereof, it may be used as it is, but in the case of electric non-conductors such as plastics, it is necessary to carry out a conductive treatment.

Here, the electroconductivity treatment is performed by a known method. For example, with ABS resin, after degreasing (sodium sulfate 20 g / l, sodium phosphate 20 g / l, surfactant 2 g / l, immersed in mixed solution at 40-60 ° C. for 3-5 minutes), etching (chromic acid). 400 g / l, sulfuric acid 40
Immerse in a mixed solution of 0 g / l at 65 to 70 ° C. for 8 to 15 minutes. ), After washing with water and after pretreatment of dipping in 50 ml / l of hydrochloric acid,
Sensitizer liquid (SnCl ₂ · 2H ₂ O 5-30 g /
1, 36% HCl 5-30 ml / l), washed with water, anti-beta solution (PdCl ₂ 0.1-0.3 g /
1, 36% HCl 1-5 ml / l). After that, electroless (chemical) Ni plating, electroless (chemical) Co plating, electroless (chemical) Cu plating, or the like is performed to perform a conductive treatment. Thereafter, any electroplating is possible. The pretreatment method differs depending on the type of resin such as polycarbonate resin, polycarbonate alloy resin, nylon resin, polyacetal resin and the like.

The method of eutectoid Co / Ni plating on the device is performed by a well-known method. For example, it is a method of adding and dissolving a Ni salt (for example, Ni sulfate or Ni chloride) to the bath composition in the method of electroplating Co described above. It can also be obtained by a method of adding and dissolving a Co salt (for example, Co sulfate or Co chloride) in a Ni plating bath.
In that case, the ratio (% by weight) of precipitated Co and Ni depends on the ratio of the number of moles of Co and the number of moles of Ni in the bath composition, and if it is 1 to 1, about 50% can be obtained. However, the current density, the bath temperature, and the area ratio of the Co and Ni electrodes used for the anode in the electroplating method are slightly different.

In Co / Ni eutectoid plating, C
The content of o is preferably 25% or more. This is because even if the Co content is less than 25%, the bactericidal and antifungal effects are exhibited, but when the Co content is 25% or more, the bactericidal and antifungal effects are almost the same as in the case of only Co plating.

In the plating, the thickness of the plating is related to the rust prevention of the base metal, and the thicker they are, the better the corrosion resistance is.
However, if it is attempted to obtain corrosion resistance only with the thickness of Co plating or Co / Ni eutectoid plating, these plating materials and plating chemicals are more expensive than those of Ni plating, for example, which is a cost disadvantage. .. Therefore, it is preferable in terms of cost to carry out Co plating or Co.Ni eutectoid plating after carrying out ordinary plating. If the type and method of plating performed as the base are those that are normally performed,
Although not limited, Ni or Cu (copper) plating or the like is common. In that case, for example, the total thickness of the Ni plating and the Co plating or the Co-Ni eutectoid plating may be the thickness that has been conventionally used for the Ni plating.

However, the thickness of Co plating or Co.Ni eutectoid plating is preferably about 2 μm or more. Even if it is less than 2 μm, for example, 1.5 μm, the bactericidal and antifungal effects are exhibited as in the case of about 2 μm or more, but it is considered that corrosion occurs in a long time and Co ions are eluted away.

Further Cr plating is performed by a known method. For example, chromic anhydride 250 g / l, sulfuric acid 3.
There is a method of plating a 0 g / l bath at a bath temperature of 40 to 55 ° C. and a cathode current density of 10 to 50 A / dm ² . Also, for example, chromic anhydride 250 g / l, sulfuric acid 1.5 g /
1, bath of sodium silicofluoride 5g / l, bath temperature 45-5
A method of plating at 6 ° C. and a cathode current density of 15 to 50 A / dm ² may be used.

The thickness of the Cr plating is preferably about 0.1 μm to about 0.5 μm. Usually the thickness of Cr plating is
0.1μ as specified in JISH8617 (1977)
m is necessary, and about 0.1 in decorative plating.
This is because if the thickness is 5 μm, the corrosion resistance and abrasion resistance are sufficient, and if the thickness is about 0.5 μm or more, it is economically disadvantageous.

[0019]

[Function] Although Cr plating has no bactericidal property, C
When o plating or Co / Ni eutectoid plating is applied,
Although the cause of sterilization is not clear, in the corrosion mechanism of Co plating or Co.Ni eutectoid plating and Cr plating, Cr plating serves as the cathode (positive electrode) and C
O plating or Co / Ni eutectoid plating is the anode (negative electrode)
It is presumed that Co ions of Co plating or Co.Ni eutectoid plating are eluted through the defects (cracks and pinholes) of Cr plating, and the eluted Co ions cause sterilization.

[0020]

【Example】

1. Bactericidal test As a test showing bactericidal property, a resistance test against Escherichia coli is shown, but it can be inferred that the same effect can be obtained with Pseudomonas aeruginosa, Staphylococcus aureus and the like.

Preparation of test bacterial solution Escherichia coil (Eschericha coil I)
FO3301) was used. The test bacterium is subcultured three times in a normal broth medium at 35 ° C for 18 hours for three times, and appropriately diluted with a sterile phosphate buffer to obtain a test bacterium solution.

Measurement medium A standard agar medium is used. Measurement method Ordinary broth culture dilution of the test strain is used as a plate-shaped sample 3c
Smear over an area of mx 3 cm and wipe off after 4 hours,
Wiping was carried out in the usual way, the residual strains of each test strain were measured, and these were repeated 3 times and expressed as an average value.

Preparation of Samples Each sample was subjected to the following treatments before plating. Polishing → Alkali degreasing → Washing → Immersion in 1% to 3% sulfuric acid aqueous solution for about 30 seconds to 60 seconds → Washing → Drying After plating, it was thoroughly washed with water and then naturally dried. Number of Escherichia coli The number of bacteria immediately after smearing of the test strain was 4.5 × 10 ⁵ .

Plating Thickness The theoretical plating thickness in plating is expressed by m / A · P (unit cm). Here, m is the amount of precipitation (g), A is the surface area of the object to be plated (cm ² ), and P is the density of the metal to be deposited (g).
/ Cm ³ ). For example, the density P of Co is 8.83 g.
/ Cm ³ , the electrochemical equivalent (Amper · h, where h is time) is 1.099, and the valence is divalent, but the deposition current efficiency is close to 100%, so the current is 0 at the surface area of 10 cm ^2. .4 Amper flow and electrolysis for 10 minutes, m is 1.099 × (10 ÷ 60) × 0.4 = 0.0
732/10 × 8.83 = 8.29 × 10 ⁻⁴ cm = about 8
μm.

In Co / Ni eutectoid plating, the density P of Ni is 8.90 g / cm ³ , and the electrochemical equivalent is 1.09.
5, the valence is divalent, and since these values are almost the same as Co, the plating thickness was calculated in the same way as when only Co was plated. However, the ratio of Co contained in the plating is almost determined by the ratio of Comol / Nimol in the solution, but as described above, it depends on the current density and bath temperature, and shows a uniform current distribution on the surface. There is some error because it does not exist.

Component content The component content was quantitatively analyzed with an energy dispersive X-ray spectrometer (EDAX manufactured by Phillips). In addition, the component analysis value in the following examples shows wt%.

Example 1 Stainless steel (SUS304) had a bath composition of Co2
Co plating was performed at a cathode current density of 20 A / dm ² for 1 minute at room temperature in a bath of 50 g / l and concentrated hydrochloric acid 130 ml / l, and after washing with water, bright Co plating (liquid composition;
00g / l, Co chloride 45g / l, boric acid 30g / l,
Saccharin 0.8 g / l, 1-4 butynediol 1.2
g / l) to a thickness of about 4 μm, and then Cr plating with a hexavalent Cr plating bath (Sergent bath) to a thickness of about 0.2.
5 μm. The number of E. coli was 330.

Example 2 Stainless steel (SUS304) had a bath composition of Co2
Co plating is performed in a bath of 50 g / l and concentrated hydrochloric acid of 130 ml / l at a cathode current density of 20 A / dm ² for 1 minute at room temperature, and after washing with water, a normal Co chemical plating bath (bath composition: C
_{oSO 4 · 7H 2 O14.1g / l} , Na 3 C 6 H 5 O
₇・ 2H ₂ O 59g / l, (NH ₄ ) ₂ SO ₄ 66
g / l, NaH ₂ PO ₂ · H ₂ O 22 g / l, bath temperature approx. 80 ° C, PH 10.2), chemical Co plating is carried out until the thickness becomes approx. 4 μm, followed by washing with water, then hexavalent Cr Cr plating with a plating bath (Sergent bath) to a thickness of approximately 0.25
μm. The number of E. coli was 320.

Example 3 A brass plate was plated with bright Ni (liquid composition; 240 g of Ni sulfate).
/ L, Ni chloride 45 g / l, boric acid 30 g / l, saccharin 2 g / l, 1-4 butynediol 0.3 g / l) to a thickness of about 15 μm, and then bright Co plating (liquid composition; Co sulfate 200 g / l) 1, Co 45 g / l, boric acid 30 g / l, saccharin 0/8 g / l, 1-4 butynediol 1.2 g / l) to a thickness of about 5 μm, and then the normally used hexavalent Cr Cr plating was carried out to a thickness of about 0.25 μm using a plating bath (Sergent bath). The number of E. coli was 350.

Example 4 Semi-bright Ni plating on a steel plate (liquid composition; sulfuric acid Ni240)
g / l, Ni chloride 45 g / l, boric acid 30 g / l, coumarin 0.05 g / l, formalin 0.3 ml / l) to a thickness of about 10 μm, and then bright Ni plating (liquid composition;
Sulfuric acid Ni 240 g / l, Ni chloride 45 g / l, boric acid 3
0 g / l, saccharin 2 g / l, 1-4 butynediol 0.3 g / l) was applied to a thickness of about 5 μm, followed by thorough washing with water, and then bright Co plating (liquid composition; Co sulfate 200 g / l).
1, Co45 g / l chloride, boric acid 30 g / l, saccharin 0.8 g / l, 1-4 butynediol 1.2 g / l)
To a thickness of about 5 μm, and then the 6
Cr plating was carried out to a thickness of about 0.3 μm using a valent Cr plating bath (Sergent bath). The number of E. coli was 380.

Example 5 Stainless steel (SUS304) had a bath composition of Ni 2 chloride.
Ni plating was performed at a cathode current density of 15 A / dm ² for 1 minute at room temperature in a bath of 40 g / l and concentrated hydrochloric acid 120 ml / l, and after washing with water, bright Ni plating (liquid composition; Ni 2 sulfate)
40 g / l, Ni chloride 45 g / l, boric acid 30 g / l,
Saccharin 2g / l, 1-4 butynediol 0.3g /
l) to a thickness of about 3 μm, and bright Co plating (liquid composition: Co 200 g / l sulfate, Co 45 g / l chloride, boric acid 30 g / l, saccharin 0.8 g / l, 1-4 butynediol 1.2 g / l ) To a thickness of about 1.5 μm,
After washing with water, Cr plating was then performed to a thickness of about 0.25 μm in a hexavalent Cr plating bath (Sergent bath). The number of E. coli was 420.

Example 6 Stainless steel (SUS304) had a bath composition of Ni 2 chloride.
Ni plating was performed in a bath of 40 g / l, concentrated hydrochloric acid 120 ml / l at a cathode current density of 15 A / dm ² at room temperature for 1 minute, and after washing with water, Co / Ni eutectoid plating (liquid composition: Co80 g / l sulfate, Sulfuric acid Ni 190 g / l, NiCl 45
g / l, boric acid 30 g / l) to a thickness of about 4 μm,
After washing with water, Cr plating was then performed to a thickness of about 0.25 μm in a hexavalent Cr plating bath (Sergent bath). Note that Co
The Co content in Ni eutectoid plating was about 25%. The number of E. coli was 480.

Example 7 A stainless steel (SUS304) having a bath composition of Ni 2 chloride
Ni plating was carried out at a cathode current density of 15 A / dm ² for 1 minute at room temperature in a bath of 40 g / l and concentrated hydrochloric acid 120 ml / l, and after washing with water, Co / Ni eutectoid plating (liquid composition; sulfuric acid Co 60 g / l, Sulfuric acid Ni 190 g / l, NiCl 45
g / l, boric acid 30 g / l) to a thickness of about 4 μm,
After washing with water, Cr plating was then performed to a thickness of about 0.25 μm in a hexavalent Cr plating bath (Sergent bath). Note that Co
The Co content in Ni eutectoid plating was about 20%. The number of bacteria of E. coli was 600 or 1500, but the effect is clearly seen.

Comparative Example 1 Stainless steel (SUS304) was Cr-plated with a hexavalent Cr plating bath (Sergent bath) to a thickness of about 0.25 μm.
went. The number of E. coli was 3 × 10 ⁵ .

Comparative Example 2 A stainless steel (SUS304) having a bath composition of Ni 2 chloride
Ni plating was performed at a cathode current density of 15 A / dm ² for 1 minute at room temperature in a bath of 40 g / l and concentrated hydrochloric acid 120 ml / l, and after washing with water, bright Ni plating (liquid composition; Ni 2 sulfate)
40 g / l, Ni chloride 45 g / l, boric acid 30 g / l,
Saccharin 2g / l, 1-4 butynediol 0.3g /
1) was performed to a thickness of about 4 μm, washed with water, and then Cr-plated to a thickness of about 0.25 μm using a hexavalent Cr plating bath (Sergent bath). The number of E. coli was less than 300 at the 1st and 2nd times, but it was 2.4 × 10 ^{5 at the} 3rd time, which was not effective, and the 4th time was continued as a precaution, but 2.8 × 1.
No effect at 0 ⁵ .

2. Antifungal test As a test showing antifungal properties, resistance tests against the following two kinds of bacteria are shown. Test strain Aspergillus niger IFO6
341) and Penicillium funiculosum (Penicillium
funiculosum IFO 6345) was used.

Test Method Each surface of each sample was 3 cm × 3 cm and 0.1 bouillon was used.
After coating with ml and drying, the "mold resistance test method (J
ISZ2911-1981) ”, the test method for general industrial products was applied correspondingly.

Preparation of Samples Each sample was subjected to the following treatments before plating. Polishing → Alkali degreasing → Washing → Immersion in 1% to 3% sulfuric acid aqueous solution for about 30 seconds to 60 seconds → Washing → Drying After plating, it was thoroughly washed with water and then naturally dried.

Mold growth conditions The growth was carried out at a temperature of 28 ° C. for 4 weeks. Judgment It was visually observed and judged by the presence or absence of growth.

Example 8 Stainless steel (SUS304) had a bath composition of Co2
Co plating was performed at a cathode current density of 20 A / dm ² for 1 minute at room temperature in a bath of 50 g / l and concentrated hydrochloric acid 130 ml / l, and after washing with water, bright Co plating (liquid composition;
00g / l, Co chloride 45g / l, boric acid 30g / l,
Saccharin 0.8 g / l, 1-4 butynediol 1.2
g / l) to a thickness of about 4 μm, and then Cr plating with a hexavalent Cr plating bath (Sergent bath) to a thickness of about 0.2.
5 μm. There was no mold growth.

Example 9 A stainless steel (SUS304) having a bath composition of Co 2 chloride
Co plating is performed in a bath of 50 g / l and concentrated hydrochloric acid of 130 ml / l at a cathode current density of 20 A / dm ² for 1 minute at room temperature, and after washing with water, a normal Co chemical plating bath (bath composition: C
_{oSO 4 · 7H 2 O14.1g / l} , Na 3 C 6 H 5 O
₇・ 2H ₂ O 59g / l, (NH ₄ ) ₂ SO ₄ 66
g / l, NaH ₂ PO ₂ · H ₂ O 22 g / l, bath temperature approx. 80 ° C, PH 10.2), chemical Co plating is carried out until the thickness becomes approx. 4 μm, followed by washing with water, then hexavalent Cr Cr plating with a plating bath (Sergent bath) to a thickness of approximately 0.25
μm. There was no mold growth.

Example 10 On a brass plate, bright Ni plating (liquid composition; sulfuric acid Ni 240 g)
/ L, Ni chloride 45 g / l, boric acid 30 g / l, saccharin 2 g / l, 1-4 butynediol 0.3 g / l) to a thickness of about 15 μm, and then bright Co plating (liquid composition; Co sulfate 200 g / l) 1, Co 45 g / l chloride, boric acid 30 g / l, saccharin 0.8 g / l, 1-4 butynediol 1.2 g / l) to a thickness of about 5 μm, and then the normally used hexavalent Cr Cr plating was carried out to a thickness of about 0.25 μm using a plating bath (Sergent bath). There was no mold growth.

Example 11 Semi-bright Ni plating (solution composition; sulfuric acid Ni240) on a steel plate
g / l, Ni chloride 45 g / l, boric acid 30 g / l, coumarin 0.05 g / l, formalin 0.3 ml / l) to a thickness of about 10 μm, and then bright Ni plating (liquid composition;
Sulfuric acid Ni 240 g / l, Ni chloride 45 g / l, boric acid 3
0 g / l, saccharin 2 g / l, 1-4 butynediol 0.3 g / l) was applied to a thickness of about 5 μm, followed by thorough washing with water, and then bright Co plating (liquid composition; Co sulfate 200 g / l).
1, Co45 g / l chloride, boric acid 30 g / l, saccharin 0.8 g / l, 1-4 butynediol 1.2 g / l)
To a thickness of about 5 μm, and then the 6
Cr plating was carried out to a thickness of about 0.3 μm using a valent Cr plating bath (Sergent bath). There was no mold growth.

Example 12 A stainless steel (SUS304) having a bath composition of Ni 2 chloride
Ni plating was performed at a cathode current density of 15 A / dm ² for 1 minute at room temperature in a bath of 40 g / l and concentrated hydrochloric acid 120 ml / l, and after washing with water, bright Ni plating (liquid composition; Ni 2 sulfate)
40 g / l, Ni chloride 45 g / l, boric acid 30 g / l,
Saccharin 2g / l, 1-4 butynediol 0.3g /
1) to a thickness of about 3 μm, and then bright Co plating (liquid composition; Co sulfate 200 g / l, Co chloride 45 g / l, boric acid 30 g / l, saccharin 0.8 g / l, 1-4 butynediol 1.2 g). / L) to a thickness of about 1.5 μm, washed with water, and then a hexavalent Cr plating bath (sergeant bath)
Cr plating was performed to a thickness of about 0.25 μm. There was no mold growth.

Example 13 Stainless steel (SUS304) having a bath composition of Ni 2 chloride
Ni plating was performed in a bath of 40 g / l, concentrated hydrochloric acid 120 ml / l at a cathode current density of 15 A / dm ² at room temperature for 1 minute, and after washing with water, Co / Ni eutectoid plating (liquid composition: Co80 g / l sulfate, Sulfuric acid Ni 190 g / l, NiCl 45
g / l, boric acid 30 g / l) to a thickness of about 4 μm,
After washing with water, Cr plating was then performed to a thickness of about 0.25 μm in a hexavalent Cr plating bath (Sergent bath). Note that Co
The Co content in Ni eutectoid plating was about 25%. There was no mold growth.

Comparative Example 3 A stainless steel (SUS304) itself was tested for resistance to mold. Mold development was present.

Comparative Example 4 A stainless steel (SUS304) was Cr-plated with a hexavalent Cr plating bath (Sergent bath) to a thickness of about 0.25 μm.
went. Mold development was present.

[0048]

From the above results, Co plating or Co.
It can be seen that fungi and fungi are less likely to grow in the equipment plated with Ni eutectoid.

Since the surface is plated with Cr,
Has excellent corrosion resistance and hardness, and does not easily wear. Further, the Cr plating has a bluish color tone and is excellent in terms of decoration.

If it is desired to obtain corrosion resistance only by Co plating or Co.Ni eutectoid plating, a thickness similar to that of Ni plating, which is conventionally used, is required. And Co compound is Ni
Since it is more expensive than those of
Prior to plating or Co / Ni eutectoid plating, there is an advantage in performing normal plating on the substrate.

Claims (1)

[Claims] A device to be plated is directly or after plating is performed on the device to be plated, Co plating or Co / Ni eutectoid plating is performed, and then Cr plating is applied to the device. A method of imparting bactericidal and antifungal properties.