Cu-Cr Electrode Material via HIP and Infiltration
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Solution Overview
Problem
Conventional Cu-Cr electrode materials for vacuum interrupters face challenges in achieving high withstand voltage capability and current-interrupting capability while maintaining conductivity and mechanical strength, particularly under increased voltage conditions in capacitor circuits.
Innovation Solution
A process involving hot isostatic pressing (HIP) treatment of a molded body containing heat-resistant elements like Mo, W, Ta, Nb, and Zr with Cr powder, followed by infiltration with Cu or Ag, to enhance the degree of filling and electrical properties without compromising conductivity or mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the sintering method is used to produce Cu-Cr electrode material, then the composition ratio between Cu and Cr can be freely selected, but the gas content is higher resulting in inferior mechanical strength
Solution Approach 1:
The invention changes the fundamental processing parameter from sintering to infiltration method. By heating the Cr powder compact to temperatures not lower than the melting point of Cu, Cu infiltrates the airspaces among Cr particles, creating a dense structure with low gas content and high mechanical strength while maintaining flexible composition ratio control.
Solution Approach 2:
The invention utilizes the phase transition of Cu from solid to liquid state by heating to melting point or higher. The liquid Cu infiltrates the porous Cr powder compact, then solidifies upon cooling, creating a dense composite structure that eliminates gas pockets and enhances mechanical strength.
2Strength
If the infiltration method is used to produce Cu-Cr electrode material, then the mechanical strength is improved due to lower gas content, but the composition ratio between Cu and Cr cannot be freely selected
Solution Approach 1:
The invention establishes controlled parameter ranges for the infiltration process: heating temperature of not lower than Cu melting point (1083°C), Cr powder compact density of 2.0 to 3.5 g/cm³, and Cr content of 70 to 95 wt%. These parameter adjustments enable flexible composition control while maintaining the dense structure and high mechanical strength characteristics of the infiltration method.
3Reliability
If Cr particles with finer particle diameter are used, then the current-interrupting capacity and contact resistance are improved, but the mechanical strength may be compromised
Solution Approach 1:
The invention utilizes the porous structure created by fine Cr particles (average 10 to 50 μm) as a benefit rather than a drawback. The controlled porosity allows efficient Cu infiltration, creating a dense composite structure where fine Cr particles provide excellent electrical characteristics while the infiltrated Cu matrix provides mechanical strength.
Solution Approach 2:
The invention creates a composite material structure where fine Cr particles are embedded in a Cu matrix. The fine Cr particles (10-50 μm) provide high current-interrupting capacity and low contact resistance, while the Cu matrix provides mechanical strength and structural integrity, achieving synergistic properties.
4Temperature
If voltage two or three times the usual one is applied in capacitor circuits, then the withstand voltage capability is challenged, but arc generation causes surface damage and easy reignition
Solution Approach 1:
The Cu-Cr composite material combines Cu's high conductivity with Cr's arc resistance. The Cr particles (70-95 wt%, fine size 10-50 μm) form a protective network that resists arc erosion, while the Cu matrix provides electrical conductivity. This composite structure enables the electrode to withstand high voltages (2-3 times usual) and resist arc damage, preventing surface degradation and reignition.
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 process significantly improves the withstand voltage capability and current-interrupting capability of the electrode material, reducing contact resistance and maintaining high conductivity, thus addressing the limitations of conventional methods.
Implementation Method 1
subjecting a molded body comprising a powder of at least one kind of heat resistant element selected from the group consisting of Mo, W, Ta, Nb, V and Zr and a Cr powder or a sintered body of the molded body to a hot isostatic pressing treatment at a treatment temperature of 700 to 1100°C, a treatment pressure of 30 to 100 MPa and a treatment time of 1 to 5 hours
Implementation Method 2
infiltrating the porous body with Cu and/or Ag in an amount of 5 to 35 wt% relative to the electrode material
Data Source
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Figure 3
Figure 4~5
AI summary
A process for producing an electrode material by infiltrating a highly conductive metal such as Cu into a porous object containing heat-resistant elements. Before an infiltration step in which the highly conductive metal is infiltrated, a HIP treatment is given to a powder containing the heat-resistant elements (or to a molded object obtained by molding a powder containing the heat-resistant elements). The composition is controlled so that the HIP treatment yields a porous object which has a degree of filling of 70% or higher, more preferably 75% or higher. The highly conductive metal is infiltrated into the porous object having the controlled composition.