Mo-Cr Electrode Material via HIP and Infiltration
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Solution Overview
Problem
Conventional Cu-Cr electrode materials for vacuum interrupters lack sufficient withstand voltage capability and current-interrupting capability, especially in capacitor circuits where higher voltages lead to arc damage and reignition, and the infiltration method for improving mechanical strength is limited by mold wear and reduced filling rates.
Innovation Solution
A method involving provisional sintering of a Mo-Cr solid solution, followed by pulverization and hot isostatic pressing (HIP) treatment to achieve a high filling rate of Cu, resulting in a uniformly dispersed, fine-grained electrode material with enhanced electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the infiltration method is used to improve mechanical strength and reduce gas content, then mechanical strength is improved, but the filling rate decreases and mold wear increases
Solution Approach 1:
The patent applies preliminary action by performing HIP treatment before the infiltration process. The HIP treatment pre-densifies the Cr powder compact, creating a more suitable structure for subsequent Cu infiltration. This preliminary densification improves the filling rate during infiltration while maintaining the mechanical strength benefits of the infiltration method, effectively resolving the contradiction between filling rate and mechanical strength.
2Reliability
If Cr particles are refined to improve current-interrupting capacity and contact resistance, then electrical characteristics are improved, but the complexity of the manufacturing process increases
Solution Approach 1:
The patent applies parameter changes by optimizing the particle size distribution of Cr powder as a key parameter. By specifying Cr powder with a particle size of 45-200 mesh (particularly 70-150 mesh) and controlling the particle size distribution, the patent achieves fine Cr particle dispersion that improves current-interrupting capacity and contact resistance. This parameter optimization achieves the desired electrical characteristics while keeping the manufacturing process relatively simple, as it primarily involves selecting appropriate powder specifications rather than adding complex processing steps.
3Reliability
If higher Cr content is used to improve arc resistance and electrical characteristics, then electrical characteristics are improved, but the mechanical strength and workability deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the Cr content parameter within a specific range (3-15 wt%, particularly 5-10 wt%). This optimized Cr content provides sufficient arc resistance and electrical characteristics while maintaining adequate mechanical strength and workability. Additionally, the HIP treatment parameter optimization (temperature, pressure, time combinations) enhances mechanical strength without requiring excessive Cr content, thereby resolving the contradiction between electrical characteristics and mechanical strength through parameter optimization rather than material composition extremes.
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 method significantly improves the electrode material's withstand voltage and current-interrupting capabilities while maintaining mechanical strength and reducing the risk of mold wear, achieving a filling rate increase of 10% or more through HIP treatment, leading to a more durable and efficient vacuum interrupter.
Implementation Method 1
a provisional sintering step of sintering a mixed powder containing a powder of a heat resistant element having at least one kind selected from elements including Mo, W, Ta, Nb, V, and Zr and a powder of Cr to obtain a solid solution where the heat resistant element and Cr are dissolved
Implementation Method 2
a hot isostatic pressing treatment step of subjecting a molded body formed by molding the powder of the solid solution or a sintered body of the molded body to a hot isostatic pressing treatment
Implementation Method 3
an infiltration step of infiltrating Cu and/or Ag into an objective body obtained by the hot isostatic pressing treatment after the hot isostatic pressing treatment
Data Source
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AI summary
What is disclosed is an electrode material including a sintered body containing a heat resistant element and Cr and being infiltrated with a highly conductive material. A powder mixture of a heat resistant element powder and a Cr powder is subjected to a provisional sintering in advance, thereby causing solid phase diffusion of the heat resistant element and Cr. After a Mo-Cr solid solution obtained by the provisional sintering is pulverized, the pulverized Mo-Cr solid solution powder is molded and sintered. A sintered body obtained by sintering is subjected to a HIP treatment. The highly conductive metal is disposed on the sintered body after the HIP treatment, and infiltrated into the sintered body by heating at a predetermined temperature. By conducting the HIP treatment, the withstand voltage capability and current-interrupting capability of the electrode material are improved.