ZnO Varistor Powder Composition for High Withstand Voltage
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Solution Overview
Problem
Existing varistor powders with zinc oxide (ZnO) have inadequate withstand voltage and nonlinearity, requiring thicker composites or reduced varistor powder proportions to achieve high electric field relaxation, which compromises current-voltage nonlinear resistance characteristics and electric field relaxation effects.
Innovation Solution
A ZnO varistor powder composition with accessory ingredients like bismuth, cobalt, manganese, antimony, nickel, and aluminum, dispersed in a polymer matrix, optimized for high operating voltage and current-voltage nonlinear resistance characteristics, with specific particle size and bulk density ranges to enhance electric field relaxation composite performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the proportion of varistor powder in the electric field relaxation composite is reduced to raise withstand voltage, then the operating voltage increases, but the current-voltage nonlinear resistance characteristics deteriorate and the electric field relaxation effect is diminished
Solution Approach 1:
The patent changes the chemical composition parameters of the varistor powder by incorporating specific accessory ingredients (Bi2O3: 0.1-5.0 wt%, Co3O4: 0.1-5.0 wt%, MnO: 0.1-5.0 wt%, Sb2O3: 0.1-5.0 wt%, NiO: 0.1-5.0 wt%, Al2O3: 0.1-5.0 wt%) alongside ZnO (80-99.9 wt%). This compositional parameter change enables the varistor powder to achieve both high withstand voltage and excellent current-voltage nonlinear resistance characteristics simultaneously, resolving the contradiction between increasing withstand voltage and maintaining electric field relaxation effect.
2Stress or pressure
If the electric field relaxation composite is made thicker to raise withstand voltage, then the operating voltage increases, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent modifies the material properties of the varistor powder through controlled sintering (900-1300°C for 1-24 hours) and chemical composition adjustments, enabling high withstand voltage to be achieved through material quality rather than increased thickness. This allows the electric field relaxation composite to maintain thin dimensions while achieving the required withstand voltage performance.
3Ease of manufacture
If conventional ZnO varistor powder is used without accessory ingredients, then the manufacturing process is simple, but the current-voltage nonlinear resistance characteristics and withstand voltage are inadequate
Solution Approach 1:
The patent creates a composite varistor powder material consisting of ZnO as the base (80-99.9 wt%) combined with multiple accessory ingredients (Bi2O3, Co3O4, MnO, Sb2O3, NiO, Al2O3) in controlled amounts. This composite material approach enhances the current-voltage nonlinear resistance characteristics and withstand voltage while maintaining relatively simple manufacturing processes through conventional mixing and sintering techniques.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The optimized ZnO varistor powder composition achieves high withstand voltage and excellent electric field relaxation effects with improved current-voltage nonlinear resistance characteristics, maintaining effectiveness even in high electric field portions without compromising composite thickness or varistor powder proportion.
Implementation Method 1
a ZnO varistor powder with which a varistor powder/polymer matrix with high withstand voltage characteristics and an excellent electric field relaxation effect can be obtained
Data Source
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AI summary
A ZnO varistor powder can be obtained with high operating voltage and excellent current-voltage nonlinear resistance characteristics. In the ZnO varistor powder, the main ingredient is zinc oxide (ZnO); and at least bismuth (Bi), cobalt (Co), manganese (Mn), antimony (Sb), nickel (Ni), and aluminum (Al), calculated as Bi2O3, Co2O3, MnO, Sb2O3, NiO, and Al3+, are contained as accessory ingredients in amounts of 0.3 to 1.5 mol% Bi2O3, 0.3 to 2.0 mol% Co2O3, 0.3 to 3 mol% MnO, 0.5 to 4 mol% Sb2O3, 0.5 to 4 mol% NiO, and 0.0005 to 0.02 mol% Al3+. ZnO content is greater than or equal to 90 mol%; the bulk density is greater than or equal to 2.5 g/cc; the powder is a spherical powder in which the 50% particle diameter in the particle size distribution is 20 µm to 120 µm.