| 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. |
