共查询到20条相似文献，搜索用时 15 毫秒
1.
A series of solid-solid interfaces,consisting of ceramic-epoxy resin interface samples with a tip-plate electrode,were investigated by performing partial discharge tests and realtime electrical tree observations.A toughening agent was added to the epoxy resin at different ratios for comparison.The impact strength,differential scanning calorimetry(DSC) and dielectric properties of the cured compositions and ceramic were tested.The electric field strength at the tip was calculated based on Maxwell's theory.The test results show that the addition of a toughener can improve the impact strength of epoxy resin but it decreases the partial discharge inception voltage(PDIV) of the interface sample.At the same time,toughening leads to complex branches of the electrical tree.The simulation result suggests that this reduction of the PDIV cannot be explained by a change of permittivity due to the addition of a toughening agent.The microstructural change caused by toughening was considered to be the key factor for lower PDIV and complex electrical tree branches. 相似文献
2.
XIE Qing 《等离子体科学和技术》2016,18(3):325-330
Research on aging characteristics of epoxy resin(EP) under repetitive microsecond pulses is important for the design of insulating materials in high power apparatus.It is because that very fast transient overvoltage always occurs in a power system,which causes flashover and is one of the main factors causing aging effects of EP materials.Therefore,it is essential to obtain a better understanding of the aging effect on an EP surface resulting from flashover.In this work,aging effects on an EP surface were investigated by surface flashover discharge under repetitive microsecond pulses in atmospheric pressure.The investigations of parameters such as the surface micro-morphology and chemical composition of the insulation material under different degrees of aging were conducted with the aid of measurement methods such as atomic force microscopy(AFM),scanning electron microscopy(SEM),and X-ray photoelectron spectroscopy(XPS).Results showed that with the accumulation of aging energy on the material surface,the particles formed on the material surface increased both in number and size,leading to the growth of surface roughness and a reduction in the water contact angle; the surface also became more absorbent.Furthermore,in the aging process,the molecular chains of EP on the surface were broken,resulting in oxidation and carbonisation. 相似文献
3.
In gas-insulated lines, basin-insulators can accumulate charge under non-uniform electric fields, distorting the field distribution and potentially causing surface flashover, which threatens the stability of power systems. In this study, Atmospheric Pressure Plasma Jet (APPJ) technology was used to deposit TiO2 on the surface of alumina/epoxy (Al2O3/EP) composites. The impact of deposition of TiO2 layer on the surface morphology and chemical composition of Al2O3/EP was studied using testing methods such as Scanning Electron Microscope, X-ray photoelectron spectroscopy, Fourier Transform Infrared Spectrometer, and Energy Dispersive Spectrometer. It was found that APPJ creates a dense, rough Ti-O layer on the Al2O3/EP surface, which bonds tightly with the substrate. The efficacy of APPJ was found to depend on processing time, with optimal results observed at 3 min, DC and AC flashover voltages increased by 29.6% and 15.7%, respectively. TiO2 layer enhances the conductivity of the resin and shallows trap levels. Through the synergistic effects of various factors, surface charges are efficiently dissipated and evenly distributed. This study not only reveals the physicochemical process of TiO2 deposition via APPJ but also integrates surface characteristics with electrical performance. The findings offer a new strategy to enhance surface flashover voltage and ensure equipment safety. 相似文献
4.
Jiyuan YAN Guishu LIANG Hongliang LIAN Yanze SONG Chengkai PENG Yuchan KANG Qing XIE 《等离子体科学和技术》2021,23(6):64012-105
In this paper, plasma fluorination is combined with plasma silicon deposition to achieve step gradient modification on an epoxy resin surface. The physicochemical characteristics of samples are investigated and the electrical performances measured. The obtained results show that compared with untreated and single treated samples, the samples treated by step gradient modification significantly improve the flashover performance. According to experiment and simulation, the mechanism explanations are summarized as follows. First, it is found that the step gradient conductivity can effectively optimize the electric field distribution of a needle-needle electrode. Then, step gradient modification suppresses the accumulation of surface charge at the triple junction and makes the charge distribution more uniform. Furthermore, it can accelerate the surface dissipation on a high electrical field region and control the dissipation rate on a low electrical field region. All these results can restrain surface discharge and increase the flashover voltage. The step gradient modification method proposed in this paper provides a new idea for improving the surface insulation performance. 相似文献
5.
Non-thermal plasma surface modification for epoxy resin(EP)to improve the insulation properties has wide application prospects in gas insulated switchgear and gas insulatedtransmission line.In this paper,a pulsed Ar dual dielectrics atmospheric-pressure plasma jet(APPJ)was used for Si C_xH_yO_zthin film deposition on EP samples.The film deposition was optimized by varying the treatment time while other parameters were kept at constants(treatment distance:10 mm,precursor flow rate:0.6 l min~(-1),maximum instantaneous power:3.08 k W and single pulse energy:0.18 m J).It was found that the maximum value of flashover voltages for negative and positive voltage were improved by 18%and 13%when the deposition time was3 min,respectively.The flashover voltage reduced as treatment time increased.Moreover,all the surface conductivity,surface charge dissipation rate and surface trap level distribution reached an optimal value when thin film deposition time was 3 min.Other measurements,such as atomic force microscopy and scanning electron microscope for EP surface morphology,Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy for EP surface compositions,optical emission spectra for APPJ deposition process were carried out to better understand the deposition processes and mechanisms.The results indicated that the original organic groups(C–H,C–C,C=O,C=C)were gradually replaced by the Si containing inorganic groups(Si–O–Si and Si–OH).The reduction of C=O in ester group and C=C in p-substituted benzene of the EP samples might be responsible for shallowing the trap level and then enhancing the flashover voltage.However,when the plasma treatment time was longer than 3 min,the significant increase of the surface roughness might increase the trap level depth and then deteriorate the flashover performance. 相似文献
6.
The surface flashover of epoxy resin (EP) composites is a pivotal problem in the field of high-voltage insulation. The regulation of the interface between the filler and matrix is an effective means to suppress flashover. In this work, nano ZnO was fluorinated and grafted using low-temperature plasma technology, and the fluorinated filler was doped into EP to study the DC surface flashover performance of the composite. The results show that plasma fluorination can effectively inhibit the agglomeration by grafting –CFx groups onto the surface of nano-ZnO particles. The fluorine-containing groups at the interface provide higher charge binding traps and enhance the insulation strength at the interface. At the same time, the interface bond cooperation caused by plasma treatment also promoted the accelerating effect of nano ZnO on charge dissipation. The two effects synergistically improve the surface flashover performance of epoxy composites. When the concentration of fluorinated ZnO filler is 20%, the flashover voltage has the highest increase, which is 31.52% higher than that of pure EP. In addition, fluorinated ZnO can effectively reduce the dielectric constant and dielectric loss of epoxy composites. The interface interaction mechanism was further analyzed using molecular dynamics simulation and density functional theory simulation. 相似文献
7.
8.
B.SubbaReddy G.R.Nagabhushana 《等离子体科学和技术》2003,5(6):2093-2100
The flashover of insulator strings occurring at normal working voltages under contaminated/polluted conditions, obviously deserves serious consideration. Though much research has been gone into pollution-induced flashover phenomena but grey areas still exist in our knowledge. In the present experimental study the breakdown (flashover) voltages across gaps on insulator top surfaces and gaps between sheds (on the underside of an insulator), also the flashover studies on a single unit and a 3-unit insulator strings were carried out. An attempt has been made to correlate the values obtained for all the cases. From the present investigation it was found that resistance measurement of individual units of a polluted 3-unit string before and after flashover indicates that strongly differing resistances could be the cause of flashover of ceramic disc insulator strings. 相似文献
9.
双酚A型环氧树脂阳离子紫外光固化动力学的研究 总被引：1，自引：0，他引：1
以双酚A型环氧树脂为主体成分构成紫外阳离子光固化体系,用常规的最低光固化速度测试方法和实时傅立叶变换红外光谱法研究了各种条件对体系光固化速度的影响。结果表明,光引发剂的种类和浓度可以有效地改变光固化速度,环氧稀释剂会大幅度降低光固化速度,而羟基化合物的加入只是轻微降低光固化速度。在三元体系中,其光固化速度并不是几种作用的简单叠加,而是更加类似于羟基化合物的性质。使得通过调节合适的组分构成和配合,能够获得具有合适光固化速度的紫外阳离子光固化配方,从而会大大扩展其应用的技术领域。 相似文献
10.
本文针对船用核反应堆辐射场特点、屏蔽防护需求和使用环境条件,开展了屏蔽腻子的优化设计及应用研究。选用耐腐蚀防霉变优异、粘结度强、无毒性的双酚A环氧树脂和脂环胺固化剂作为基体材料,添加粒径约100μm的铅、聚乙烯、碳化硼等屏蔽添加剂提高屏蔽腻子的辐射防护性能。采用蒙特卡罗方法对屏蔽腻子的主要成分配比进行了优化设计。计算结果表明,碳化硼含量为5%~15%、铅含量为80%时,中子的慢化与吸收达到平衡,较高的铅含量大幅增强了其对γ射线及次级γ射线的屏蔽防护能力,使屏蔽腻子对235 U诱发裂变源的综合辐射防护能力达到最佳水平。消泡剂、分散剂、流平剂、促进剂等加工助剂的添加对屏蔽腻子快速固化、气泡排除、混合均匀、成型致密光滑起到了重要促进作用。通过样品试制和试验测试,证明了优化设计的屏蔽腻子具有优异的屏蔽性能、耐辐照老化性能、固化成型质量、粘结强度、混合浇灌施工便捷性能等,能有效满足船用核反应堆等设施屏蔽缝隙处及不规则部位的辐射防护使用需求。 相似文献
11.
本文以环氧树脂为研究对象,分析了环氧树脂对能量范围在0.001~100 MeV的伽马射线的屏蔽性能,测试了环氧树脂对60Co伽马射线的屏蔽性能,并对其进行了总剂量为93.5 kGy的伽马射线辐照处理,对辐照前后环氧树脂的密度、光学照片、力学性能、断面微观形貌、耐热性能和红外光谱进行了分析。结果表明：环氧树脂对低能(E<0.01 MeV)伽马射线的衰减主要是光电吸收作用,对中能(0.01 MeV60Co伽马射线的屏蔽性能一般。93.5 kGy伽马射线辐照导致环氧树脂老化、密度和最大耐热温度降低、力学性能增大、破坏程度低,环氧树脂可耐93.5 kGy伽马射线辐照。 相似文献
12.
Huijuan RAN Yanze SONG Jiyuan YAN Hongliang LIAN Yuchan KANG Chengkai PENG Qing XIE 《等离子体科学和技术》2021,23(9):95502-153
Epoxy resin (EP) tends to accumulate a large amount of charge on its surface when exposed to a high-voltage DC electric field,which leads to a reduction in its insulative performance and an increase in potential safety risks in power systems.To suppress charge accumulation,improve the flashover voltage of the EP,and reduce the risk of gas insulated switchgear (GIS)/gas insulated transmission line (GIL) failure,we used two plasma-etching methods,i.e.,atmospheric-pressure dielectric barrier discharge (DBD) and the atmospheric-pressure plasma jet(APPJ),to modify the surface of the EP.The surface morphology and electrical properties of the modified materials were explored as a function of time.The results show that after DBD treatment,the roughness of the sample increases by 103.9 nm,the conductivity increases by3.9?×?10~(–18)S,and the flashover voltage increases by 14.4%;after APPJ treatment,the roughness of the sample increases by 223.5 nm,the conductivity increases by 3.4?×?10~(–17)S,and the flashover voltage increases by 18%.This shows that both plasma-etching methods can improve the insulation properties of materials by improving the surface-charge characteristics.The two methods are compared with each other:the APPJ treatment method is better at improving the surface roughness and electrical properties of materials,and this flexible treatment method has greater potential in industrial applications. 相似文献
13.
When a wind turbine is struck by lightning,its blades are usually rotating.The effect of blade rotation on a turbine's ability to trigger a lightning strike is unclear.Therefore,an arching electrode was used in a wind turbine lightning discharge test to investigate the difference in lightning triggering ability when blades are rotating and stationary.A negative polarity switching waveform of 250/2500 μs was applied to the arching electrode and the up-and-down method was used to calculate the 50%discharge voltage.Lightning discharge tests of a 1:30 scale wind turbine model with 2,4,and 6 m air gaps were performed and the discharge process was observed.The experimental results demonstrated that when a 2 m air gap was used,the breakdown voltage increased as the blade speed was increased,but when the gap length was 4 m or longer,the trend was reversed and the breakdown voltage decreased.The analysis revealed that the rotation of the blades changes the charge distribution in the blade-tip region,promotes upward leader development on the blade tip,and decreases the breakdown voltage.Thus,the blade rotation of a wind turbine increases its ability to trigger lightning strikes. 相似文献
14.
Gas pressurized closing switches are one of the most important elements in FLTD-based systems. Improving the trigger performance of gas switches is useful for optimizing the output parameters and the reliability of the FLTD. In this paper, the breakdown characteristics of the trigger gap and the overvoltage gap are studied experimentally. The reasons for the different breakdown performance of the two gaps are also investigated. The results show that the breakdown delay of the trigger gap is more influenced by the trigger voltage, while the breakdown delay of the overvoltage gap is more influenced by the working coefficient and always higher than that of the trigger gap. The jitter of the trigger gap is more influenced by the trigger voltage and accounts more than 60% of the total switch jitter, while the jitter of the overvoltage gap is hardly changed with the trigger voltage as well as the working coefficient and maintains less than 1.4 ns. It is proved that the discharging product from the trigger gap can effectively reduce the breakdown delay and jitter of the overvoltage gap. Based on that, the effect and improvement of pre-ionization on the two gaps are also studied. It is concluded that the jitter of the trigger gap reduces obviously when the pre-ionization is added, while the pre-ionization almost has no effect on the jitter of the overvoltage gap. The jitter of the overvoltage gap is about two times higher than the trigger gap in the pre-ionizing switch. 相似文献
15.
《等离子体科学和技术》2016,18(3):223-229
According to the stream theory,this paper proposes a mathematical model of the dielectric recovery characteristic based on the two-temperature ionization equilibrium equation.Taking the dynamic variation of charged particle's ionization and attachment into account,this model can be used in collaboration with the Coulomb collision model,which gives the relationship of the heavy particle temperature and electron temperature to calculate the electron density and temperature under different pressure and electric field conditions,so as to deliver the breakdown electric field strength under different pressure conditions.Meanwhile an experiment loop of the circuit breaker has been built to measure the breakdown voltage.It is shown that calculated results are in conformity with experiment results on the whole while results based on the stream criterion are larger than experiment results.This indicates that the mathematical model proposed here is more accurate for calculating the dielectric recovery characteristic,it is derived from the stream model with some improvement and refinement and has great significance for increasing the simulation accuracy of circuit breaker's interruption characteristic. 相似文献
16.
17.
为了研究低能电子辐照对环氧树脂的体积电阻率、邵氏硬度、拉伸强度和官能团结构的影响,本文在电子辐照能量为30 keV,注量率1×1011 cm-2•s-1,总注量为1.6×1014 cm-2,真空度10-6 Pa条件下,结合国家标准对辐照前、后环氧树脂材料的机械性能和结构进行表征。结果表明,辐照后环氧树脂材料的体积电阻率、邵氏硬度、拉伸强度等宏观物理性能均有下降。傅里叶红外光谱图显示环氧树脂主要官能团强度降低,产生的•H、•OH等自由基与聚合物分子上的羟基与氢结合。研究结果对环氧树脂材料在辐射环境中的使用具有重要意义。 相似文献
18.
《等离子体科学和技术》2020,22(4):44003
The DC electrical resistivity-temperature characteristic is an important property for insulating materials to operate at a high stress level. In order to improve the DC electrical resistivity at elevated temperature in a targeted way, a positive temperature coefficient(PTC) material(Ba Ti O3-based compound(BT60)) was selected as the filler in this paper, whose electrical resistivity has a PTC effect when the temperature exceeds its Curie temperature. The BT60 was treated with hydrogen peroxide and(3-Aminopropyl) triethoxysilane. Epoxy composites with different loadings of BT60 fillers(0 wt%, 0.5 wt%, and 2 wt% of epoxy) were prepared, denoted as EP-0, EP-0.5, and EP-2. It was shown that BT60 was able to maintain the DC breakdown strength when its loading was less than 2 wt% of epoxy. As the temperature exceeds 60 °C,BT60 will compensate for the negative temperature coefficient effect of epoxy resin to some extent. The electrical resistivity of EP-2 was improved by 55% compared with that of neat epoxy at 90 °C. It was found that the potential barrier at the grain boundary of BT60 and the deep traps in the interface between BT60 and the epoxy resin hinder the migration of carriers and thus increase the electrical resistivity of epoxy composite. 相似文献
19.
Surface coating technology is an effective way to solve the interface insulation problem of DC GIS/GIL basin insulators, but the performance of the coating will change greatly, and the insulation strength will be completely lost, after long-term use in the extreme conditions of corona erosion. In this research, the multi-needle-plate electrode platform was constructed to explore the long-term use performance of SiC-doped nanocomposite exposed to corona discharge in SF6 gas. Samples with a high SiC content have advantages in maintaining physical and chemical properties such as elemental composition, erosion depth, surface roughness and mass loss. The nanocomposite doped with 6 wt.% SiC has prominent surface insulation strength after long term exposure to corona, and the others are close to losing, or have completely lost, their insulating properties. Furthermore, the degradation mechanism of physicochemical properties of composite exposed to corona discharge was investigated with the proposed ReaxFF MD model of energetic particles from SF6 decomposition bombarding the epoxy surface. The reaction process of SF particles and F particles with the cross-linked epoxy resin, and the SiC nanoparticles providing shelter to the surrounding polymer and mitigating their suffering direct bombardment, have been established. The damage propagation depth, mass loss and surface roughness change of nanocomposite material bombarded by SF6 decomposition products is reproduced in this simulation. Finally, the deterioration mechanism of insulation properties for the SiC-doped composite was elucidated with DFT analysis. The band gap of the molecule containing S drops directly from the initial 7.785 eV to 1.875 eV, which causes the deterioration of surface electric properties. 相似文献
20.
等效导热系数（ETC）是表征复合材料导热性能的重要参数,与连续相导热系数kc、分散相导热系数kd、分散相填充率?、分散相形状及排列方式等密切相关。因此,复合材料等效导热系数的预测是一个非常复杂的过程。虽然目前存在多种复合材料等效导热系数计算模型,但这些模型在预测固-固二元复合材料等效导热系数时仍存在较大的不确定性,因此,应根据不同的应用工况选择预测精度较高的等效导热系数计算模型。本文首先总结了目前广泛应用的颗粒状分散相固-固二元复合材料等效导热系数预测方法,包括已有经验或理论模型、最小热阻法、热阻网络法、数值模拟方法、渐进均匀化方法、逾渗理论方法等,然后基于国内外开展的固-固二元复合材料等效导热系数实验或数值模拟结果,综合评价已有经验或理论模型,给出不同应用工况下预测精度较高的等效导热系数经验或理论模型。 相似文献