| Tungsten
has good performance in many aspects, such as strong hardness,
anti-friction, heat resistance, lower coefficient of linear
expansion，lower coefficient of friction and easy to be matched
with other materials. It is most valuable material to mechanical
seals products.
Tungsten Carbide mainly used
as following:
1) Cobalt
based alloy: Tungsten-Cobalt alloy is the
alloy which content major of Tungsten Carbide and cobalt as
the bonding agent, it can be used in powder metallurgy. Made
by press and sintered process. The anti-friction performance
of the cobalt is 15-20 times stronger than the best HSS, and
1-2 times heat spread than HSS, but it is easy to be oxidation,
poor anti-corrosive performance. The mainly Chinese code are:
YG6,YG8,YG15.
2) Nickel
based alloy: It is the alloy which content
major of Tungsten Carbide and nickel as the bonding agent,
made by press and sintered process，anti-corrosive，but the
intensity only the 70-80% of cobalt based tungsten carbide
alloy. Code YWN8.
3) Nickel-chrome
based alloy: good performance of anti-corrosive，strong
intensity and hardness，and it has the special characteristic—no
magnetism, Chinese Code: W7.
4) Overlay
alloy:Overlay tungsten carbide alloy included
cobalt based and chrome based，the cobalt based one maily used
in friction pairs. Other countries called this kind of alloy
as “Stellite” as it’s special light itself. Because weak in
hardness and not distributing balancely itself, so it is poor
in anti-friction, it is seldom usded for pump mechanical seal
at present, but it is widely used in cartridge seals.
5) Furthermore,
steel bonded carbide, RC bonded carbide, chrome bonded carbide.
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