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Description:
Tungsten filaments are mostly produced with ammonium paratungstate
(APT) as raw material. The general process is to roast ammonium
paratungstate in air at about 500℃ to tungsten trioxide, or
slightly reduce it to blue tungsten oxide in hydrogen at about
450℃. The tungsten filaments for making incandescent lamp filaments
need to be doped with a small amount of potassium oxide, silicon
oxide and aluminum oxide in tungsten trioxide or blue tungsten
oxide. The total amount of the three should not exceed 1%. This is
the tungsten filament doping process invented by Baz in 1922. The
tungsten oxide after doping is reduced to metal tungsten powder
with hydrogen. The reduction process is generally carried out in
two steps: the first step is reduced to tungsten dioxide (brown
tungsten oxide) at about 630℃, and the second step is reduced to
metal tungsten powder at about 820℃. The purpose of the two-step
reduction is to make the added potassium fully play its role and
control the powder particle size. The doped tungsten powder
obtained in this way is then pressed into a long and thin square
bar in a special mold. The square bar is energized in hydrogen and
sintered by self-resistance heating (temperature up to about
3000℃). After sintering, the density of the tungsten bar can reach
more than 85% of the theoretical value. This tungsten bar can be
processed into a tungsten rod with a diameter of about 3mm by
rotary forging, and then further processed into tungsten wires of
various thicknesses by die drawing. For example, the diameter of
the tungsten wire used in a 220V, 15W incandescent lamp is about
15?m, while the diameter of the tungsten wire used in a 10000W
bromine tungsten lamp is about 1.25mm. Thinner tungsten wires, such
as the tungsten wire of a 220V, 10W incandescent lamp with a
diameter of about 12?m, must be made by electrolytic corrosion.
When the diameter of the tungsten wire reaches the micron level, it
is difficult to accurately measure its diameter with a conventional
caliper. Therefore, internationally, the thickness of tungsten wire
with a diameter of less than 0.2mm is usually expressed by the
weight of a 200mm long wire segment. For example, the diameter of
the 15W incandescent lamp tungsten wire mentioned above can be
expressed as 0.679mg/200mm.
Specifications:
mm | diameter | length | Diameter tolerance | surface | State |
rod | 8.0~16.0 | 10~850 | 10~660 | Black | forged |
3.0~8.0 | 10~5000 | 10~800 | Black | forged | |
wire | 1.5~3.0 | 10~8000 | 10~1600 | Black | drawing |
0.5~1.5 | 10~8000 | 10~2650 | Black | drawing |
Packing & Delivery:
To better ensure the safety of your goods, professional, environmentally friendly, convenient and efficient packaging services will be provided.
Our inspection equipment:
FAQ:
Q: What information should I let you know if i want to get a
quotation?
A: The required material dimension
(Thickness*Width*Length,diameter*length; if possible, please kindly
supply us drawings).
The required more information, such as Surface Condition, Tolerance
Request, The Quantity, and other mechanical and technical details.
If it is possible, please also provide the application of products,
we will recommend the most suitable products with details for
confirmation.
Q: How do you gurantee the quality of the products?
A: Each step of production and finished products will be carried
out inspection by QC department before storing in the warehouse. NG
goods are not allowed in the completed goods warehouse.
Q: Can you guarantee the prompt delivery?
A: Yes, when we get your inquiries, not only we will evaluate the
more competitive price, but also we can get the most reasonable
delivery time. So the prompt delivery can be guaranteed.
Q: What is the shipping cost?
A: The shipping cost is determined by the destination port, weight,
packing size, total CBM of the products, we will try best to get the most reasonable shipping cost
from the forwarders or express couriers to help you save more
money.
Q:What is the transportation way?
A:If the Gross Weight ≤45kg, it's better by express such as TNT, DHL, FedEx,, etc.
If the Gross Weight between 45kg to 100kg, by express or by air to
your nearest airport can be both considered.
If the Gross Weight ≥ 100kg ,you can choose by Air or Sea to the
nearest port.