Electro-thermal-mechanical computations in ZnO arrester elements

Boggs, S.A.; Kuang, J.; Andoh, Hideyasu; Nishiwaki, S.

doi:10.1109/elinsl.1998.694834

Cited by 3 publications

(5 citation statements)

References 4 publications

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“…Desai and Haque [1] have used the uniaxial tensile testing technique to measure Young's modulus of ZnO nanowires. It is interesting to note that the authors reported fracture strains as high as 15% for the nanowires, which is unusual considering that bulk ZnO is a brittle material at the bulk scale [22]. Young's modulus of nanowires can also be extracted from the resonant frequency of a single nanowire, induced by an alternating electric field.…”

Section: Review Of Nanomechanical Experimental Techniques and Young'smentioning

confidence: 97%

Synthesis and Elastic Characterization of Zinc Oxide Nanowires

Manoharan

Desai

Neely

et al. 2008

Journal of Nanomaterials

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Zinc oxide nanowires, nanobelts, and nanoneedles were synthesized using the vapor-liquid-solid technique. Young's modulus of the nanowires was measured by performing cantilever bending experiments on individual nanowires in situ inside a scanning electron microscope. The nanowires tested had diameters in the range of 200–750 nm. The average Young's modulus, measured to be 40 GPa, is about 30% of that reported at the bulk scale. The experimental results are discussed in light of the pronounced electromechanical coupling due to the piezoelectric nature of the material.

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Section: Review Of Nanomechanical Experimental Techniques and Young'smentioning

confidence: 97%

Synthesis and Elastic Characterization of Zinc Oxide Nanowires

Manoharan

Desai

Neely

et al. 2008

Journal of Nanomaterials

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“…where S m denotes the area of the triangle m, the ZnO varistor film thickness s is taken to be 4 15 10 − × cm , ρ = 5.6 g/cm 3 is the mass density of ZnO, P m = 0.5P ij and C p the thermal capacity of ZnO ceramics taken to be [41]:…”

Section: Temperature Calculations and Thermal Stressesmentioning

confidence: 99%

“…Dirichlet boundary conditions at the top and bottom (electrode) locations and Neumann "zero current" transverse requirement at the left and right boundaries were applied. This amounted to a simultaneous solution of a system of non-linear, coupled equations, as already stated in the context of equation (4). The solving of this non-linear system led to dynamic evaluation of the distributed currents and localized power generation within the sample.…”

Section: Temperature Calculations and Thermal Stressesmentioning

confidence: 99%

“…In particular, the presence of Bi-ions trapped at the grain-boundaries is thought to be responsible for a highly nonlinear behavior. Due to the highly nonlinear current-voltage (I-V) characteristics (empirically I ~ V a , where a can be 50 or higher) and excellent current/energy absorption capabilities, varistors are widely used as electrical surge arresters [1][2][3][4]. They afford superior transient protection against over-voltages in electronic circuits and electrical systems.…”

Section: Introductionmentioning

confidence: 99%

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Electro-thermal Simulation Studies for Pulsed Voltage Induced Energy Absorption and Potential Failure in Microstructured ZnO Varistors

Zhao

Joshi

Lakdawala

2007

IEEE Trans. Dielect. Electr. Insul.

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A time-dependent, two-dimensional model is used to study internal heating effects and possible device failure in ZnO varistors in response to a high-voltage pulse. The physics and qualitative trends discussed here should hold for materials with internal microstructured grain boundaries. Our analysis is based on an electro-thermal, random Voronoi network. It allows for the dynamic predictions of internal failure and to track the progression of hot-spots and thermal stresses. Results here show that application of high voltage pulses can lead to the attainment of Bi 2 O 3 melting temperatures in the grain boundaries and an accelerated progression towards failure. Comparisons between uniform and normally distributed barrier breakdown voltage showed relatively small difference. Physically, this is shown to be associated with the applied bias regime and grain size. It is argued that reduction in grain size would help lower the maximum internal stress. This is thus a desirable feature, and would also work to enhance the hold-off voltage for a given sample size.Index Terms -Energy absorption, ZnO varistor, electro-thermal failure, voronoi network, high voltage pulsing.

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“…The presence of Bi‐ions trapped at the grain‐boundaries (GBs) is thought to be responsible for a highly nonlinear current–voltage ( I – V ) characteristics. Empirically I – V a , where a can be 50 or higher, and these devices are ideally suited for use in electrical surge arresters 1–4 …”

Section: Introductionmentioning

confidence: 99%

Electrothermal Model Evaluation of Grain Size and Disorder Effects on Pulsed Voltage Response of Microstructured ZnO Varistors

Zhao

Joshi

Hjalmarson

2008

Journal of the American Ceramic Society

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Time‐dependent, two‐dimensional, electrothermal simulations based on random Voronoi networks have been developed to study the internal heating, current distributions and breakdown effects in ZnO varistors in response to high‐voltage pulsing. The simulations allow for dynamic predictions of internal failures and to track the progression of hot‐spots and thermal stresses. The focus is on internal grain‐size variations and relative disorder including micropores. Our results predict that parameters such as the hold‐off voltage, internal temperature, and average dissipated energy density would be higher with more uniform grains. This uniformity is also predicted to produce lower thermal stresses and to allow for the application of longer duration pulses. It is shown that the principal failure mechanism arises from internal localized melting, while thermal stresses are well below the thresholds for cracking. Finally, detrimental effects of micropores have been quantified and shown to be in agreement with experimental trends.

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Electro-thermal-mechanical computations in ZnO arrester elements

Cited by 3 publications

References 4 publications

Synthesis and Elastic Characterization of Zinc Oxide Nanowires

Synthesis and Elastic Characterization of Zinc Oxide Nanowires

Electro-thermal Simulation Studies for Pulsed Voltage Induced Energy Absorption and Potential Failure in Microstructured ZnO Varistors

Electrothermal Model Evaluation of Grain Size and Disorder Effects on Pulsed Voltage Response of Microstructured ZnO Varistors

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