Feasibility Study of Carbon Fiber Ceramic Matrix
Composites Used in Mechanical Seal Friction Pairs
J G Wang, Z P Guo
*
and A N Zhang
School of Mechanical Engineering, Xi’an Shiyou University, Xi’an,
Shaanxi(710065), China
Abstract. The choice of mechanical seal friction material has great influence on the sealing
performance. As a new composite material, carbon fiber ceramic matrix composites have
excellent corrosion resistance, high mechanical strength, good heat resistance and heat
transfer performance, is the good choice of mechanical seal matching material. In the paper,
the temperature field and leakage value are simulated by computer when carbon fiber ceramic
matrix composites are applied to the friction pair. And the simulation results are verified by
experiments. Studies have shown that when carbon fiber ceramic matrix composites are used
in mechanical seal friction pairs, the sealing performance is significantly improved, including
reducing temperature rise, leakage and wear.
1. Introduction
The material of the mechanical seal friction pair has a great influence on the sealing effect [1].
Carbon fiber ceramic matrix composites is a new type of composite material. It has low density, good
thermal conductivity and corrosion resistance. The good thermal conductivity significantly reduces
the temperature rise of the sealed end face, prevents the thermal damage of the sealed end face, and is
advantageous to the stability of the liquid film between the friction pairs, thereby avoiding the sealing
failure. Smaller density increasess follow-up to moving parts, and good wear resistance can extend
the life of the seal ring. In summary, there are many benefits to using this material for sealing friction
pairs. In this paper, ANSYS software is used to study the temperature field between the static and
dynamic rings of the friction face. First, the temperature field under different materials is studied;
then, the speed and pressure of the friction pair are changed respectively to obtain the corresponding
temperature field; finally, the temperature of several points is measured by a mechanical seal test
bench to verify the accuracy of the numerical simulation.
2. CFD model
This article chooses SG04U type mechanical seal structure. Figure 1 shows the structure. And the
seal area ratio is 1.2952. The seal spring specific pressure is 0.15 MPa. The axial thickness of the
moving ring is 24mm. The axial thickness of the stationary ring is 30mm. The medium is 20#
mechanical oil. The thickness of the liquid film is 4μm. And the flow state is laminar [2-3].
638
Wang, J., Guo, Z. and Zhang, A.
Feasibility Study of Carbon Fiber Ceramic Matrix Composites Used in Mechanical Seal Friction Pairs.
In Proceedings of the International Workshop on Materials, Chemistry and Engineering (IWMCE 2018), pages 638-643
ISBN: 978-989-758-346-9
Copyright © 2018 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved

Figure 1. SG04U type mechanical seal structure.
The following assumptions are made in the calculation:
1 The temperature field distribution is steady;
2 The temperature field is axisymmetric;
3 The heat flux density is evenly distributed on the sealing surface;
4 Consider only convection heat transfer and neglect heat radiation;
5 Fluid parameters do not change with temperature.
3. Result and discussion
3.1. Material
The following figure 2 and 3 are radial temperature distribution curves of the mechanical seal and
static ring end face obtained by using origin data processing software. There are four groups of
matching materials. The first group is carbon fiber ceramic matrix composites and graphite. The
second group is hard alloy and graphite. The third group is carbon fiber ceramic matrix composites
and hard alloy. The fourth group is SiC and hard alloy. The sealing shaft speed is 2000r/min. The
pressure in the sealing chamber is 0.4Mpa. The sealing medium is 20# mechanical oil. And the
sealing chamber temperature is 30°C. In the figure, the abscissa represents the temperature
measurement point number of the seal ring from the outer diameter to the inner diameter, and the
ordinate represents the magnitude of the temperature value.
Feasibility Study of Carbon Fiber Ceramic Matrix Composites Used in Mechanical Seal Friction Pairs
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Figure 2.Temperature field paired with hard material.
Referring to Figure 2, when the moving ring is graphite, the stationary ring is respectively the
carbon fiber ceramic matrix composite and hard alloy. Also, the carbon fiber ceramic matrix
composite performs better as a static ring. At this circumstance, the temperature field between the
sealing faces is lower than the temperature field of the hard alloy.
Figure 3.Temperature field paired with soft material.
Referring to Figure 3, when the moving ring is a hard alloy, the stationary ring is a carbon fiber
ceramic matrix composite material and a silicon carbide alloy respectively. And carbon fiber ceramic
matrix composites perform better than silicon carbide.
In summary, it can be concluded that the carbon fiber ceramic matrix composite material performs
excellently under the condition of soft-to-hard material pairing in the absence of abrasive particles or
slurry in the sealing medium. This material makes the temperature drop very obvious and the radial
temperature change is small.
IWMCE 2018 - International Workshop on Materials, Chemistry and Engineering
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3.2. Presure
Figures 4 and 5 below show the sealed end surface temperature field when the seal chamber pressure
is changed using origin data processing software. The pressure in the sealing chamber was 0.2 MPa,
0.3 MPa, 0.4 MPa, 0.5 MPa, and 0.6 MPa, respectively. The sealing medium is 20# mechanical oil.
In the figure, the abscissa represents the temperature measurement point number of the seal ring from
the outer diameter to the inner diameter, and the ordinate represents the value of the temperature
value (unit: K).
Figure 4. Moving ring temperature under different pressures.
Figure 5. Stationary ring temperature under different pressures.
It can be concluded that carbon fiber ceramic matrix composites are used to material of the seal
friction pair. When the pressure in the seal chamber increases, the temperature of the contact surface
of the seal friction pair also increases. The reason is that the increase in pressure in the sealing
chamber leads to an increase in the heat flux of the sealing face. This leads to an increase in the heat
flux density of the ring annulus. Finally, the temperature of the end surface rises.
3.3. Rotating speed
Figures 6 and 7 below show the seal face temperature field for changing the seal speed. The rotation
speeds were 1000 r/min, 1500 r/min, 2000 r/min, 2500 r/min, and 3000 r/min, respectively. The
sealing medium is 20# mechanical oil. In the figure, the abscissa indicates the temperature
Feasibility Study of Carbon Fiber Ceramic Matrix Composites Used in Mechanical Seal Friction Pairs
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measurement points of the seal ring from the outer diameter to the inner diameter, and the ordinate
indicates the temperature value (unit: K).
Figure 6. Moving ring temperature at different rotation speeds.
Figure 7.Stationary ring temperature at different rotation speeds.
It can be found that changes in the rotational speed of the seal shaft directly affect the flow state
of the medium. The convective heat transfer coefficient of the friction ring changes. The higher the
speed, the more heat is generated. Therefore, the higher the seal shaft speed, the higher the seal ring
face temperature.
4. Experimental
The accuracy of the simulation results is verified experimentally. The static ring center temperature
of the mechanical seal of the carbon fiber ceramic matrix composite was tested under two conditions.
Experiment one: The sealing medium is 20# mechanical oil. The pressure in the sealing chamber
is 0.4 MPa. Sealing chamber temperature 30 °C. Carbon fiber ceramic matrix composites are moving
ring materials. Graphite is a stationary ring material. Change the seal shaft speed (1000r/min,
1500r/min, 2000r/min, 2500r/min, 3000r/min) to obtain the static ring center temperature.
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Experiment 2: The seal medium is 20# mechanical oil. Sealed shaft speed 2000r/min. Sealing
chamber temperature 30 °C. Carbon fiber ceramic matrix composites are moving ring materials.
Graphite is a stationary ring material. Change the pressure in the sealed chamber (0.2MPa, 0.3MPa,
0.4MPa, 0.5MPa, 0.6MPa) to obtain the center temperature of the stationary ring.
By comparing the curves in the figure 8, the numerical simulation data is accurate. First of all, the
trend of temperature change under pressure change and speed change is consistent. Second, there is a
small difference between the simulated and experimental values of the sample points. Therefore, the
simulation results have strong persuasive power.
5. Conclusions
As a mechanical seal friction pair material, carbon fiber ceramic matrix composites meet the basic
sealing requirements.
Whether it is with soft materials or hard materials, carbon fiber ceramic matrix composites
perform better. The temperature is lower, and the temperature field is more even and has a better
sealing effect.
Carbon fiber ceramic matrix composites are more suitable for hard to soft sealing conditions.
Under this condition, the temperature drop is even more pronounced.
The pressure in the seal chamber and the speed of the seal shaft have a great influence on the
temperature of the end face. The face temperature increases as the pressure in the seal chamber
increases. The face temperature increases as the rotational speed of the seal shaft increases.
References
[1] Zhao S and Wang X L. 2015 The effects of surface texture on the wear properties of
mechanical seals made of metal and polymers in Tribology, vol 06, 761-767. (in Chinese).
[2] Wang B and Hao M M. 2009 Numerical study on flow field of new-type hydrostatic-dynamic
hybrid lubrication seal in Lubrication Engineering, vol 07, 62-65+73. (in Chinese).
[3] Chen H L and Peng Z D. 2010 Study on temperature field of stern shaft mechanical seal based
on Ansys in Lubrication Engineering, vol 35. 73-76. (in Chinese).
Figure 8.Comparison of experimental and simulated data.
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