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The company mainly offers sealing products
made in Silicon carbide (SIC). SIC is a typical covalent bond
compound. The atom of SI and C is small, bond is short and covalence
is strong, these features give SIC the following properties:
high hardness, good mechanical strength, low coefficient of
friction, good radiation resistance, self lubrication, chemical
stability, heat resistance, good heat conduction, good as a
mating face. SIC is a kind of ceramic material, so it's brittle
and no good in terms of shock resistance.
There are four types of SIC,
made by different technology and process - namely, Reaction
Bonded SIC (SIC RB), Sintered pressure less SIC (SSIC), hot
pressurized SIC, and vaporous SIC. For the pump, mixer and
other general machinery application, SIC RB and SSIC are most
commonly used. The hot pressing SIC and vaporous SIC are applied
in special field because their cost is very high and the different
shape is less.
We are now producing the following
SIC RB and SSIC, as well as other SIC related products:
1) ZKS-1: Reaction bonded (self-combine)
SIC
α-SIC is mixed up with carbon, according to different particle
sizes. SI is involved in the reaction process, during sintering.
So, there is about 10% free Silicon present in the SIC RB,
which limits its application. This material cannot be used
in hydrofluoric acid, strong alkali and oxidizing medium,
and it's max working temperature is 1200℃.
2) ZKS-2: Self sintered pressure less
SIC (SSIC)
Pure α-SIC powder and a little additives are molded into different
shapes, which are then sent to the sintering process under
2000 to 2300℃. The purity of SSIC products is above 98%, and
the max. Working temperature up to 1600℃. SSIC is chemically
inert to almost all kinds of acids, alkali, and strong oxidizing
medium. So it's an excellent heat resistance, wear resistance
and corrosion resistance ceramic material.
3) ZKS-3A、ZKS-3B: SIC with 5 - 30% graphite
content
With the evolving technology, the regular SIC material cannot
meet the demand of high PV value applications. So the company
developed a new grade of material - graphite loaded SIC (with
5 - 30% graphite content), which increases the self-lubrication
and thermal conduction of the material. This material is also
featured by low coefficient of friction and improved coefficient
of thermal expansion. So it in a way combines the advantage
of SIC and carbon.
4) ZKS-4: SIC with controlled porosity
A very thin liquid film is to be maintained between the seal
faces, to ensure smooth operation of the mechanical seals
and a long seal life. The brand new grade of SSIC - SIC with
controlled porosity - is to make 2 - 12% porosity (holes)
on the SSIC seal face. These holes are in the size of 50 to200
micron meter, and are round, closed, independent from each
other, and are spread our evenly. Such kind of products will
help to maintain a stable liquid film between the seal faces,
and decrease the friction heat. So, it will help to build
up a reliable seal, with long seal life.
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