Rings of mechanical seals
Rings of mechanical seals,wear resistance,high modulus of
elasticity,low temperature coefficient of linear expansion
An important role in the design of mechanical seals is played by
elements directly involved in the process of friction, it is
O-rings of mechanical seals. The sealing mechanism, regardless to
the mechanical seal design, assumes contact on the flat end of
these rings forming a friction pair. From the point of view of
assemble reliability, it is extremely important to ensure the
operation of a friction pair with the lowest friction and wear
coefficients in each particular case. Ring designs and materials
are determined by a large set of operational, design and process
parameters. Among the main indicators that determine reliability of
a friction pair are:
- chemical resistance of the material in the medium to be sealed;
- wear resistance of material combination of friction pair;
- thermal conductivity of the material (heat removal from the
friction zone, reduction of the temperature gradient and,
accordingly, temperature stresses and deformations);
- high modulus of elasticity (the resistance to force deformations);
- low temperature coefficient of linear expansion;
- manufacturability (the possibility to provide a high quality
surface treatment).
Related Data
| Main component | 99%Al2O3 | S-SiC | ZrO2 | Si3N4 |
|
Physical
Property | Density | g/cm3 | 3.9 | 3.1 | 6 | 3.2 |
| Water Absorption | % | 0 | 0.1 | 0 | 0.1 |
| Sinter Temperature | °C | 1700 | 2200 | 1500 | 1800 |
Mechanical
Property | Rockwell Hardness | HV | 1700 | 2200 | 1300 | 1400 |
| Bend Strength | kgf/mm2 | 3500 | 4000 | 9000 | 7000 |
| Compression Intensity | Kgf/mm2 | 30000 | 20000 | 20000 | 23000 |
Thermal
Property | Maximum working
temperature | °C | 1500 | 1600 | 1300 | 1400 |
thermal expansion
coefficient
0-1000°C | /°C | 8.0*10-6 | 4.1*10-6(0-500°C) | 9.5*10-6 | 2.0*10-6(0-500°C) |
| 5.2*10-6(500-1000°C) | 4.0*10-6(500-1000°C) |
| Thermal Shock resistance | T(°C) | 200 | 250 | 300 | 400-500 |
| Thermal Conductivity | W/m.k(25°C | 31 | 100 | 3 | 25 |
| 300°C) | 16 | 100 | 3 | 25 |
Electrical
Property | Resisting rate of Volume | ◎.cm | | | | |
| 20°C | >1012 | 106-108 | >1010 | >1011 |
| 100°C | 1012-1013 | – | – | >1011 |
| 300°C | >1012 | – | – | >1011 |
Insulation Breakdown
Intensity | KV/mm | 18 | semiconductor | 9 | 17.7 |
| Dielectric Constant (1 MHz) | (E) | 10 | – | 29 | 7 |
| Dielectric Dissipation | (tg o) | 0.4*10-3 | – | – | – |
Ceramic materials and cemented carbide meet the above requirements,
which makes them widely used for the production of mechanical seal
rings. The most widely used reactive silicon carbide, sintered
silicon carbide, aluminum oxide and cemented carbide. In a number
of cases, as a material of the friction pair, various versions of
carbon materials (impregnated graphites, etc.) are used together
with ceramics.
All types of ring sizes for mechanical seals are produced in
series.
Non-standard rings are made according to customer’s drawings. It is
possible to apply grooves on rings for dry gas-dynamic seals.
We manufactures products from structural brands of graphite,
impregnated graphite, antifriction graphite
Graphite has unique properties:
- electrical conductivity;
- heat resistance (sublimation effect);
- poor wettability by many metals;
- strength, anomalously increasing with temperature increasing;
- possibility to work with dry friction (self-lubrication)
Due to its unique properties, graphite products are used in many
industries:
- production of ferrous, non-ferrous and precious metals;
- engineering;
- chemistry, petrochemistry and oil refining;
- glass industry;
- analytical laboratories;
- power engineering and electrical engineering.
