Decomposition characteristics of C5F10O/air mixture as substitutes for SF6 to reduce global warming

Article abstract of DOI:10.1016/j.jfluchem.2018.01.015

Sulfur hexafluoride (SF₆) is widely used in the power industry but is a serious greenhouse gas. Many researchers committed to achieving sustainable development of the power industry are finding alternatives to SF₆ gas. C₅F₁₀O performs well in terms of environmental protection, insulation, and safety and is a potential environment-friendly alternative gas. In this paper, the insulation and decomposition characteristics of C₅F₁₀O/air gas mixture were examined using gas-insulation performance test platform, and decomposition products were detected by gas chromatography–mass spectrometry. The formation mechanism and distribution of C₅F₁₀O decomposition products were analyzed through reactive molecular dynamics method and density functional theory. The influence of air on the decomposition of C₅F₁₀O was also evaluated. Results showed that the decomposition of C₅F₁₀O/air gas mixture mainly produces CF₃[rad], C₃F₇[rad], C₄F₇O[rad], CO, CF₂[rad], CF[rad], F[rad] and CF₄. The breakdown voltage of C₅F₁₀O/air gas mixture decreased slightly after repeated breakdown tests, and CF₄, C₂F₆, C₃F₈, C₃F₆, C₄F₁₀, CF₂O were detected. These results can serve as a reference for the systematic comprehension of the decomposition characteristics of C₅F₁₀O/air gas mixture and for related engineering applications.

Full text of DOI:10.1016/j.jfluchem.2018.01.015

JournalofFluorineChemistry208(2018)65–72
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
Decomposition characteristics of C5F10O/air mixture as substitutes for SF6 to
reduce global warming
Yi Lia, Xiaoxing Zhanga,⁎, Song Xiaoa, Qi Chena, Dibo Wangb
a
School of Electrical Engineering, Wuhan University, Wuhan 430072, China
Electric Power Research Institute, China Southern Power Grid, Guangzhou 510623, China
b
A R T I C L E I N F O
A B S T R A C T
Keywords:
C5F10O/air
Molecular dynamics
ReaxFF forcefield
SF6 alternative gas
Sulfur hexafluoride (SF6) is widely used in the power industry but is a serious greenhouse gas. Many researchers
committed to achieving sustainable development of the power industry are finding alternatives to SF6 gas.
C5F10O performs well in terms of environmental protection, insulation, and safety and is a potential environ-
ment-friendly alternative gas. In this paper, the insulation and decomposition characteristics of C5F10O/air gas
mixture were examined using gas-insulation performance test platform, and decomposition products were de-
tected by gas chromatography–mass spectrometry. The formation mechanism and distribution of C5F10O de-
composition products were analyzed through reactive molecular dynamics method and density functional
theory. The influence of air on the decomposition of C5F10O was also evaluated. Results showed that the de-
composition of C5F10O/air gas mixture mainly produces CF3%, C3F7%, C4F7O%, CO, CF2%, CF%, F% and CF4. The
breakdown voltage of C5F10O/air gas mixture decreased slightly after repeated breakdown tests, and CF4, C2F6,
C3F8, C3F6, C4F10, CF2O were detected. These results can serve as a reference for the systematic comprehension
of the decomposition characteristics of C5F10O/air gas mixture and for related engineering applications.
1. Introduction
liquefaction temperature of up to 26.9 °C [8], its insulation performance
is excellent with a dielectric strength twice than that of SF6; thus it has
Sulfur hexafluoride (SF6) gas has excellent insulation and arc per-
formance and has been widely used in the power industry. According to
statistics, about 80% SF6 in the world is used in various types of gas-
insulated equipment in the power industry, such as high-voltage circuit
breakers, gas-insulated lines (GIL) and so on [1]. However, SF6 is a
serious greenhouse gas, with its lifespan in the atmosphere exceeding
3200 years and greenhouse effect potential (GWP) that is 23,500 times
that of CO2 [2–4].The Kyoto Protocol explicitly listed SF6 as one of the
six restricted greenhouse gases in 1997 [5]. Over the past five years, SF6
gas has grown in the atmosphere by 20%, and the constantly increasing
greenhouse gas emissions will lead to an increase in global average
temperatures of about 4 °C (Celsius degree) in 2100 [6,7]. In order to
realize the coordinated and sustainable development of the power in-
dustry, and gradually eliminate the dependence on SF6, searching for an
environment-friendly SF6 alternative gas as an insulating medium used
in electrical equipment is of great urgency.
the potential of reaching the insulation strength of SF6 at the same at-
mospheric pressure by mixing with a low liquefaction temperature
buffer gas such as CO2, N2, and air. Moreover, C5F10O is nontoxic and
has an occupational exposure limit time average of 225 ppmv (parts per
million). [8]. Therefore, C5F10O has great properties in terms of en-
vironmental protection, insulation, and safety.
Several scholars tested the insulation performance of C5F10O and its
mixtures and found that C5F10O/air gas mixture has excellent insulation
properties, and has potential use in medium-voltage and high-voltage
electrical equipment [8–10]. For engineering applications, Asea Brown
Boveri Ltd. (ABB) has developed a switch cabinet with C5F10O/air gas
mixture as insulation medium. It has passed the relevant standard test
of the International Electrotechnical Commission (IEC) and has been
carried out in test run successfully [8].
To evaluate the performance of gas-insulated medium comprehen-
sively, besides the insulation and arc extinguishing characteristics, the
decomposition characteristics also need to be investigated. In long-term
operations or fault conditions, the internal insulation defects of the
equipment caused by aging will lead to partial discharge (PD) or
flashover, resulting in the decomposition of gas insulation medium. For
In the past two years, C5F10O and its gas mixture have attracted
attention in the field of alternative gas research. Its molecular structure
is shown in Fig. 1. The GWP value of C5F10O is only 1, and its ozone
depression potential index (ODP) is 0. Although C5F10
O has a
⁎
Corresponding author at: School of Electrical Engineering, Wuhan University, BaYi Street No.299, Wuhan, Hubei Province, China.
E-mail address: xiaoxing.zhang@outlook.com (X. Zhang).
https://doi.org/10.1016/j.jfluchem.2018.01.015
Received 17 December 2017; Received in revised form 27 January 2018; Accepted 30 January 2018
Availableonline01February2018
0022-1139/©2018ElsevierB.V.Allrightsreserved.

Y. Li et al.
JournalofFluorineChemistry208(2018)65–72
performance test platform and GC-MS. The decomposition mechanism
of C5F10O/air gas mixture were theoretically explored by reactive
molecular dynamics method (ReaxFF-MD) and density functional
theory (DFT). The main decomposition paths and the influence of
temperature on the reaction enthalpy were analyzed. Related research
results provide a reference for a systematic and comprehensive under-
standing of the decomposition characteristics of C5F10O/air gas mixture
and for related engineering applications.
2. Methods
2.1. Experimental method
The gas insulating performance test platform was used to conduct
multiple breakdown tests on the C5F10O/air gas mixture, and the de-
composition products were detected by GC-MS.
Fig. 1. Molecule structure of C5F10O.
Fig. 2 shows the wiring diagram of the test system. The system
consists of test transformers, protection resistors, capacitive voltage
divider, and gas chamber. The transformer is used to provide high
voltage; and the protective resistor is used to protect the test trans-
former, and to avoid the damage of the test transformer after over-
current due to the breakdown. The capacitive divider is used to measure
the actual voltage across the electrodes. The volume of the test chamber
is 20 L; the main constituent material is 304 L stainless steel and poly-
tetrafluoroethylene with excellent corrosion resistance, to avoid the
chemical reaction between C5F10O and gas chamber materials, and to
ensure the accuracy of the composition test results.
The ball electrode, with radius of 25 mm and electrode interval of
5mm, was used to simulate a slightly non-uniform electric field. The
electrode material is red copper. The electric field utilization coefficient
is used to describe the electric fields with different uniformities, which
is defined as f = Eav /Emax, where Emax is the maximum electric field
intensity, and Eav is the average electric field intensity [16]. The electric
field utilization coefficient f of the ball electrode is 0.5168, hence, the
electric field distribution between the ball electrode models is a slightly
non-uniform electric field.
Before the test, the air tightness of the chamber was checked, and
nitrogen was used to the wash the gas three times to eliminate the in-
fluence of the impurity in the air chamber. A mixture of 13.6% C5F10O,
69.12% N2, and 17.28% O2 is then added to 0.15 Mpa [14]. Then, the
step-stress test (boost rate of about 0.5 kV/s) is used by applying the AC
voltage to the positive and negative electrodes of the chamber until
breakdown, and the instantaneous value of the breakdown voltage is
recorded. The above test was repeated 30 times with an interval of
2 min. At the end of the test, the gas in the chamber was collected, and
the gas components were tested by gas chromatography mass
example, the most widely used insulation medium, SF6 can decompose
and produce SO2F2, SO2, SOF2, and many other products [11]. The
decomposition properties of gas insulating medium are closely related
to its self-recovery characteristics, and the types of decomposition
components also determine its safety. Therefore, the study of the de-
composition characteristics of a new insulating medium needs to be
done first, before engineering application.
At present, research on the decomposition characteristics of C5F10
O
and its gas mixture have made some progress. Tatarinov et al. tested the
decomposition of C5F10O/N2 and C5F10O/air mixtures using dielectric
barrier discharge (DBD) and found that the main products are C4F10
,
C6F14, C5F12, C3F6, and C3F8; and with the increase in applied voltage,
the decomposition rate of C5F10O increases. The decomposition rate of
C5F10O/N2 gas mixture is slower than that of C5F10O/air gas mixture at
the same condition [12,13]. Hyrenbach et al. detected the composition
of C5F10O/air gas mixture used in the switch cabinet as the insulating
medium under long-term operation and internal arc faults by gas
chromatography-mass spectrometry (GC–MS). Apparently, C3F7H and
C3F6 are the main decomposition products under normal operating
conditions. The components of CO, CO2, CF4, C3F8, and C2F6 are de-
tected under internal arc tests [14]. Our team has calculated the pos-
sible decomposition paths of C5F10O from the theoretical level and the
effects of trace water were evaluated. The reaction enthalpy of each
possible path, the ionization characteristics and toxicity of the decom-
position products were analyzed [15,16]. We also studied the decom-
position characteristics of C5F10O/CO2 gas mixture and found that the
main decomposition species are CF3·and CO [17].
In this paper, the insulation and decomposition characteristics of
C5F10O/air gas mixture were first tested using gas-insulation
Fig. 2. Experimental system diagram.
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Y. Li et al.
JournalofFluorineChemistry208(2018)65–72
Fig. 3. Representative snapshots of C5F10O/air and C5F10O systems.
Fig. 6. Time evolution of C5F10O/air gas mixture and major products at 2600 K.
Fig. 4. Breakdown voltage at different breakdown times.
model the interactions in a chemical system. ReaxFF overcomes the
shortcomings of traditional molecular dynamics simulations that
cannot simulate dynamic chemical reactions. It has been successfully
applied in the chemical reaction kinetics simulation [18,19]. In ReaxFF
force field, the energy function is described as follows [20],
spectrometry (Shimadzu Ultra 2010plus with CP-Sil 5 CB column).
2.2. Calculation method
To further clarify the decomposition mechanism C5F10O/air mix-
ture, both the ReaxFF-MD and DFT calculations were adopted. ReaxFF
is a reactive force field method which uses the concept of bond order to
Fig. 5. Chromatogram of C5F10O/air gas mixture
after breakdown test.
67

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JournalofFluorineChemistry208(2018)65–72
Table 1
Initial generation time and reaction paths of decomposition products.
Product
Generation temperature (K)
Generation time (ps)
Reaction path
ΔE (kcal/mol)a
C4F7O%,CF3%
C3F7%,CO
CF%
CF2%
CF4
2600
2600
2600
2600
3000
270.625
380
414.375
740
A
B
C
D
E
C5F10O → CF3•+C3F7CO•
78.71
82.80
138.45
77.74
−103.53
C5F10O → CF3•+C3F7•+CO
C3F7CO• → 2CF3•+CF•+CO
CF3• → CF2• + F•
806.250
CF3• + F•→CF4
a
at mGGA-M06L level with ZPE correction and enthalpy correction at 2600 K.
The box length of C5F10O system is 155 Å, which contains 100 C5F10
O
molecules with a density of 0.01186 g/cm3. The density of each system
corresponds to the actual density of gas mixture under 25 °C 0.1 Mpa.
To obtain more optimized models, the system was initially minimized
using NVE (the number of atoms, volume, and potential energy is
constant) ensemble for 5 ps at 5 K, and then equilibrated with the NVT
(the number of atoms,volume, and temperature constant) ensemble for
10 ps at 1000 K [19]. Then, the NVT simulations were carried out at
different temperatures for 1000 ps with a time step of 0.1 ps to explore
the decomposition process of C5F10O. The temperature was controlled
by the method of a Berendsen thermostat with a 0.1 ps damping con-
stant [21]. All the ReaxFF-MD simulations in this paper were performed
based on the ReaxFF module of ADF (Amsterdam Density Functional)
[22].
The DFT calculations were also performed based on the Dmol 3
module of the Materials studio to obtain the influence of temperature
and the enthalpy of each decomposition path [23–25]. The reactant and
product of each decomposition pathway were geometrically optimized
using meta-generalized approximation (mGGA) treated by M06L func-
tions, and the double numerical atomic orbital augmented by d-polar-
ization (DNP) is used as the basis set [26,27]. The energy obtained was
corrected from the zero-point energy (ZPE). The frequency analysis was
also did to check the stability of each particle and provide temperature
corrections on thermodynamic quantities such as enthalpy. And the
reaction enthalpy of each decomposition path at different temperatures
can be obtained using the following equation,
Fig. 7. Relative energy change of each decomposition paths (at mGGA-M06L level with
ZPE correction and enthalpy correction at 2600 K).
Erelative = Eproducts − Ereactants
where Ereactants and Eproducts represent the energy of reactants and
products. ESPE, EZPE, E△T correspond to the single point energy (SPE),
zero point energy and correcting values of enthalpy, respectively.
We also did transition states search using the complete linear syn-
chronous transit (LST) and quadratic synchronous transit (QST)
methods for each reaction path to get the reaction activation energy
[28].
(1)
Ereactants (products) = ESPE + EZPE + EΔT
(2)
Fig. 8. Enthalpy change of decomposition paths at 300–3000 K.
3. Results and discussion
Esystem = Ebond + Eover + Eunder + Eval + Epen + Etors + Econj + EvdWaals
where Ebond denotes the bond energy; Eover and Eunder correspond to the
over and under coordinated atom in the energy contribution, respec-
tively; and Eval, Epen, Etors, Econj, EvdWaals, and ECoulomb represent the
valence angle term, penalty energy, torsion energy, conjugation effects
to energy, nonbonded van der Waals interaction, and Coulomb inter-
action, respectively.
Two periodic cubic boxes were established. The decomposition
process of C5F10O was simulated; and the dynamic reaction paths, the
formation mechanism of the main products and their distribution were
systematically analyzed.
Fig. 3 shows the configuration of built models. The box length of
C5F10O/air system is 264 Å, which contains 100 C5F10O molecules, 84
O2 molecules, and 316 N2 molecules with a density of 0.00344 g/cm3.
+ ECoulomb
(1)
3.1. Test results
Fig. 4 shows the distribution of the breakdown voltage at different
breakdown times and the linear fitting result. The first breakdown
voltage of the gas mixture was 27.2 kV; the 30th breakdown voltage
was 26.8 kV, which was 0.4 kV lower than the first breakdown voltage.
The linear fitting result (R value is 0.6762) shows that the breakdown
voltage of the gas mixture decreases with the increase in the breakdown
times, indicating that the composition of the gas mixture after repeated
breakdown tests has changed. The decomposition products with rela-
tively poor insulation properties were produced, causing the reduction
in the breakdown voltage.
Fig. 5 describes the chromatogram of C5F10O/air gas mixture after
breakdown test. The qualitative analysis was carried using the National
Institute of Standards and Technology database (Nist14.0) and standard
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JournalofFluorineChemistry208(2018)65–72
Fig. 9. Time evolution of C5F10O decomposition products
at different temperatures.
gas chromatography. CF4, C2F6, C3F8, C3F6, C4F10, CF2O, C6F14, and
other decomposition products are produced in the C5F10O/air gas
mixture after breakdown. Among them, the peak area of CF4 is the
biggest, which indicates that its content is the highest.
We have detected the decomposition products of C5F10O/N2 gas
mixture in our earlier study and found that the content of C2F6 is the
highest, while CF2O was not detected [16]. The mass production of
CF2O is related to the addition of oxygen. The O2 molecules or O% atom
69

Y. Li et al.
JournalofFluorineChemistry208(2018)65–72
major decomposition products at this temperature. The initial genera-
tion time and reaction path of each decomposition products can be
obtained according to the ReaxFF results. (As shown in Table 1).
According to the simulation results, the main particles and products
produced by C5F10O are C3F7CO% (C4F7O%), CF3%, C3F7%, CO, CF%, CF2%,
and CF4. These particles were then optimized at mGGA-M06L level
based on the DFT method. The Harmonic vibrational frequencies and
total energy of all the species were then calculated to obtain the en-
thalpy of each reaction path.
C5F10O began to decompose at 270.625 ps, through path A produ-
cing C4F7O% and CF3%, and the reaction needs to absorb 78.71 kcal/mol.
At 380 ps, C5F10O decomposed, producing C3F7% and CO through re-
action path B, which need to absorb 82.80 kcal/mol. C4F7O% decom-
posed at 414.375 ps, producing CF3%, CO, and CF%, and this process
required to absorb 138.45 kcal/mol. In addition, CF2% and CF4 were
found at 2600 K and 3000 K, which were formed by the decomposition
of CF3% or combination of CF3% with F%. It should be noted that the
direct C5F10O decomposition pathways belong to bond-cleavage reac-
tions. And these bond-cleavage reactions are determined as barrierless
without transition states using the complete LST and QST methods.
Fig. 7 shows the relative energy of each decomposition path. We can
find that there are two main decomposition paths of C5F10O (path A and
B), producing C4F7O%, CF3%, C3F7%, CO, and other particles.
Fig. 10. Maximum number of produced products at different temperatures.
Fig. 8 shows the enthalpy change of the main decomposition paths
with temperature from 300–3000 K. The enthalpy of the paths A, B, and
C decreases significantly as the temperature increases, indicating that
the reaction is more likely to occur; that is, the increase in temperature
contributes to the decomposition of C5F10O. In addition, the enthalpy of
path D did not change significantly with temperature, indicating that
the increase in temperature had little effect on the formation of CF2%.
3.2.2. Production distribution at different temperatures
At present, the C5F10O/air gas mixture is mainly used in engineering
applications, in which the content of C5F10O is generally less than 20%
[8].Therefore, the C5F10O/air gas mixture model with a mixing ratio of
2:8 is constructed. Partial discharge (corona discharge) and arc dis-
charge are the two most common types of discharges in electrical
equipment. The temperature in the core region of arc discharge and
corona discharge is 3000–12,000 K, and 700–1200 K, respectively
[28–29]. The reactive molecular dynamics simulations of C5F10O/air
gas mixture system were then carried out to reveal the decomposition
mechanism at different temperatures.
Fig. 11. Final decomposition amount of C5F10O at different temperatures.
can react with free radicals such as CF3% generated by C5F10O under the
action of high-energy electric field to form CF2O.
3.2. Decomposition mechanism of C5F10O/air gas mixture
Fig. 9 shows time evolution of C5F10O decomposition products with
temperature from 2400 K to 3400 K. The decomposition rate of C5F10O/
air gas mixture significantly accelerated with the increase of tempera-
ture. For example, only 6 C5F10O molecules decomposed at the end of
the simulation at 2400 K, and 79 C5F10O molecules are decomposed at
3400 K. When the temperature is below 2800 K, the decomposition
amount of C5F10O at the end of simulation is below 50%.
3.2.1. Decomposition paths of C5F10O/air gas mixture
In order to reveal the decomposition paths of C5F10O/air gas mix-
ture, the reactive molecular dynamics simulations were carried out. It
was found that the gas mixture begins to decompose largely at 2600 K.
Fig. 6 describes the time evolution of C5F10O/air gas mixture and its
Table 2
Final amount of decomposition products at different temperatures.
Major species
Temperature
2400 K
2600 K
2800 K
3000 K
C5F10
O
C5F10O/air
C5F10
O
C5F10O/air
C5F10
O
C5F10O/air
C5F10
O
C5F10O/air
CF3%
CO
C3F7%
CF%
C4F7O%
F%
CF2%
CF4
32
13
7
6
3
0
0
0
0
11
5
3
0
3
0
0
0
0
86
45
18
30
6
16
9
7
23
14
8
2
4
6
0
0
1
142
72
21
60
11
48
24
49
38
63
29
11
7
6
14
0
151
82
37
74
18
74
19
57
42
91
48
17
12
6
43
2
2
0
1
C%
7
4
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JournalofFluorineChemistry208(2018)65–72
The maximum number of produced products at different tempera-
C5F10O and air needs further study.
tures is given in Fig. 10. The maximum number of C4F7O%, CF3%, C3F7%,
CO, CF%, CF2%, and CF4 increased with the increase in temperature. The
content of CF3· in different temperature conditions is the highest among
all the products, followed by CO and F%. In addition, since air contains a
certain amount of oxygen, the formation of CF2O occurred during the
simulation process.
3.3. Environmental effects of C5F10O/air gas mixture
As mentioned above, C5F10O exhibits very low GWP compared to
SF6 and the GWP value of C5F10O gas mixture with the molar fraction
lower than 20% is less than 0.7 [16]. And it does not contribute to
ozone depletion. The atmospheric degradation of C5F10O does not lead
to the generation of long chain acids that are of environmental concern
[14].
The decomposition products of C5F10O, such as CF4, C2F6, C3F8,
C4F10 and C6F14 belong to Perfluorocarbons. The GWP values of these
substances are 7390, 12200, 8830, 8860 and 9300, which is higher than
C5F10O. It should be noted that the concentration of decomposition
products is relatively low under normal working and even fault con-
ditions. Hyrenbach et al. detected the composition of C5F10O/air gas
mixture used in the switch cabinet and found that the content of CF4,
C2F6, C3F8, C4F10 and C3F6 under arc discharge is at ppm level. The max
concentration of CF4, C2F6, C3F8, C4F10 and C3F6 is 100 ppm, 10 ppm,
19 ppm, 2 ppm and 14 ppm, respectively [14]. Therefore using C5F10O/
air gas mixture can effectively reduce emissions.
According to the results shown in Fig. 10, the contents of F% and CO
increase as the reaction progress at different temperatures. The C4F7O%
produced by the decomposition of C5F10O is irregular with the reaction
time, especially at the temperature of 3000 K. At the beginning of the
reaction, a large amount of C4F7O% is produced, but the content of this
product is maintained at a relatively stable level after 100 ps. This may
be related to the existence of a certain dynamic balance between the
generation and decomposition of C4F7O% during the decomposition
process. The content of CF%, CF2%, F%, and CF4 increased with the re-
action progress at different temperatures, and the production rate in-
creased with the temperature. Among these products, F% and CF4
showed rapid growth trend at temperatures above 2800 K. The content
of C3F7· showed a tendency to increase first and then decrease under the
condition of 3400 K, indicating that the high temperature caused the
decomposition of C3F7%. In addition, the yield and rate of three free
radicals of CF2%, CF%, and CF4 in C5F10O/air system began to increase
dramatically at temperatures above 3000 K; while under 3000 K, the
contents were low. The generation rate of CF3% slowed down after
600 ps at 3200 K and 3400 K. This trend is due to the combination of
CF3% and F%, which produces a large amount of CF4 and consumes CF3%
and F% in the system.
Actually, electron collision ionization, thermal decomposition and
photoionization are the main factors leading to the decomposition of
gas in a discharge. Under the condition of arc or spark discharge, the
dissociation of gas molecules is mainly caused by electron collision
ionization or high temperature. Under the condition of partial discharge
or corona discharge, the dissociation of gas molecules is mainly caused
by electron collision ionization due to the low temperature of the dis-
charge area. And the type and relative content of particles generated by
the discharge will determine the composition of the decomposition
products to a certain extent. According to the simulation results,
C5F10O/air gas mixture mainly produces CF3%, F%, CO and C3F7% at high
temperature. The breakdown tests shows that CF4, C2F6, C3F8, C3F6,
C4F10, CF2O, C6F14 were generated. And the formation of these products
needs the participation of CF3%, F% and C3F7%. Thus the results of
ReaxFF are consistent with breakdown experiments.
4. Conclusion
In this paper, the insulation and decomposition characteristics of
environment-friendly alternative gas C5F10O/air gas mixture were stu-
died experimentally and theoretically. First, the breakdown test of
C5F10O/air gas mixture was carried out using the gas insulation per-
formance test platform, and the components after the test were detected
by GC-MS. Then the decomposition mechanism of C5F10O/air gas
mixture under different temperature conditions are revealed compre-
hensively by using the method of reactive molecular dynamics and
density functional theory. The main decomposition path, the by-
products, and their distribution were analyzed.
There are two main decomposition paths of C5F10O producing
C4F7O%, CF3%, C3F7%, CO, and other particles. With temperature in-
crease, the decomposition rate of C5F10O accelerates, and further pro-
duce CF2%, CF%, F%, CF4, C2F6, C3F8, and other decomposition products.
Also, the breakdown voltage of the gas mixture decreases with the in-
crease in the breakdown times. CF4, C2F6, C3F8, C3F6, C4F10, CF2O,
C6F14 are detected in the C5F10O/air gas mixture after breakdown. And
the generation of CF2O is relative to the existence of oxygen.
Acknowledgement
3.2.3. Effect of air on the decomposition of C5F10
In order to investigate the effect of air on the decomposition of
C5F10O, we carried out simulations for pure C5F10 system at
O
The current work is supported by the Science and Technology
Project of China Southern Power Grid (No. ZBKJXM20170090)
O
2400–3000 K. Fig. 11 shows the comparison of the decomposition of
C5F10O and C5F10O/air gas mixture at the same temperature. There are
49 C5F10O molecules decomposed in the C5F10O system at 2400 K, and
only 6 C5F10O molecules decomposed in C5F10O/air gas mixture
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