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Technical InformationIonized Wire for Air Cleaner

In recent years, more and more air cleaners have been used in living and working environments.
For houses, the sale of air cleaners have remarkably increased with a catch phrase of collecting mite, mold, dust and pollen that are said to be the cause of allergy.
In work places, there is a problem of smoking, and many companies provide smoking spots, in which air cleaners play an important role.
In addition, air cleaners are used in the production shop of precision instrument and semiconductor that are easily damaged by dust.
An air cleaner has a construction in which relatively large dust in the air is caught by a filter installed all over the cleaner and the dust of micro-size passing through the filter is charged by corona discharge electrode and attracted by a dust collecting filter charged by reverse electrode. As a result, the air blown out of the air cleaner is clean without dirty particle.
There are two types of corona discharge electrodes to be used in an air cleaner. The one is of a needle type and the other is of a wire type, and NIPPON TUNGSTEN supplies the wire type electrode made of tungsten. Our corona discharge tungsten wire began with the production of charge wire for PPC and, through the improvement of basic properties of charge wire, has reached the quality of charged wire for air cleaner (referred to as ionized wire) having an excellent durability. In addition, we are producing platinum-plated drawn wire (patented, Hei-78882) as a new product of corona discharge wire so as to improve the quality.
We are offering ionized wires having various types of surface treatment as shown in Table-1 however, in the case of plated wires, they have a limit in diameter due to the characteristics of production process.

<Table 1>
Type Feature
Graphite tungsten wire Black tungsten wire whose surface is covered with carbon
White tungsten wire Graphite tungsten wire whose carbon surface is finished to white
Mirror-finished tungsten wire White tungsten wire whose surface is further polished to be smooth having metallic luster, suitable for negative charge type copying machine and the like which require a stable corona discharge at the initial stage
Oxidized tungsten wire White tungsten wire whose surface is forcedly oxidized, classified into two types with color, gold and dark blue, used widely
Gold-plated tungsten wire White tungsten wire whose surface is plated with gold by approximately 0.3オm thickness, used widely same as the oxidized tungsten wire
Gold-plated drawn tungsten wire Gold-plated tungsten wire which is plated thick and drawn several times so as to improve the gold layer in denseness and fitness to tungsten
Platinum-plated tungsten wire Gold-plated tungsten wire to which platinum plating is added, especially suitable for positive charge type copying machine
Platinum-plated drawn tungsten wire Platinum-plated tungsten wire which is plated thick and drawn several times so as to improve the platinum layer in denseness and fitness to tungsten, especially suitable for positive charge type copying machine
The ionized wire having surface treatment is added with terminals in various shapes according to customer's requirement. An ionized wire cannot be free from exposure to oxidized atmosphere including O3 generated by corona discharge and adhesion of dust collected by corona discharge. Tungsten is easy to oxidize and, by the adhesion of SiO2, which is the main component of dust in the air, the oxidation is promoted and the surface of tungsten is corroded. Then the tungsten deteriorates. To inhibit such phenomenon for a certain period, it is effective to coat (plate) Au or Pt on the surface of ionized wire, and the effect becomes larger as the plated film becomes thick. Though the normal plating thickness of our product is 0.3?m, a plating up to 1?m is possible at customer's request. Photo 1 shows the result of four weeks of accelerated test in which ionized wires having oxidized surface and ionized wire having Au-plated surface were installed to an actual air cleaner and subjected to a partially intensified charge. As the photograph shows, the corrosion on the oxidized surface is more excessive than that on the Au-plated surface.

Photo 2 shows the residual Au-coated layers of 0.3?m Au-plated ionized wire and 1?m Au-plated ionized wire applied to an air cleaner. The coated layer of 1?m Au-plated ionized wire remains all over the surface after the elapse of 40 days. To the contrary, the coated layer of 0.3?m Au-plated ionized wire peeled off only in a day.

  1. Overall filter (Catches coarse dust in dirty air.)
  2. Ionized portion (Gives positive charge to fine dust by means of ionized wire.)
  3. Dust collecting section (Attracts positively-charged dust by negative electrode.)
  4. Fan (Blows clean air.)


  • TEL +81-942-50-0053 / FAX +81-942-50-0054
Nippon Tungsten Co., Ltd.
2-8, Minoshima 1-chome, Hakata-ku, Fukuoka, 812-8538 Japan
Phone TEL +81-942-50-0053 / FAX +81-942-50-0054
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