Cu-Cr Electrode Material Refinement via Sintering and Infiltration
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Solution Overview
Problem
Conventional Cu-Cr electrode materials for vacuum interrupters face challenges in achieving enhanced withstand voltage capability and current-interrupting capability, particularly under increased voltage conditions in capacitor circuits, where surface damage and arc reignition occur due to insufficient refinement and dispersion of Cr particles.
Innovation Solution
A method involving provisional sintering of a mixed powder containing heat-resistant elements like Mo, W, Ta, Nb, and Zr with Cr, followed by pulverization and main sintering, and subsequent Cu infiltration, to achieve a solid solution with refined and uniformly dispersed Cr particles, improving mechanical strength and electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Cr particles are refined to finer particle diameter to improve current-interrupting capacity and contact resistance, then electrical characteristics are improved, but the mechanical strength and structural stability deteriorate due to increased porosity and gas content
Solution Approach 1:
The invention creates a composite structure where Cr particles are embedded within a Cu matrix. The Cu base material fills the airspaces between Cr particles, forming a composite material that combines the arc resistance of Cr with the mechanical strength and conductivity of Cu, resolving the contradiction between fine Cr particle dispersion and structural integrity
Solution Approach 2:
The invention utilizes a porous sintered Cr structure as the base framework, where controlled porosity is maintained but filled with Cu material. This approach allows the Cr particle network to provide electrical characteristics while the Cu infill provides mechanical strength, transforming the harmful porosity into a beneficial structural feature
2Reliability
If Cr powder is added to Cu base material to improve electrical characteristics, then withstand voltage capability is enhanced, but the manufacturing complexity increases due to multiple processing steps required for uniform dispersion
Solution Approach 1:
The invention performs preliminary sintering of the Cr powder to form a sintered Cr body before Cu infiltration. This preliminary action creates a stable Cr framework that facilitates subsequent Cu impregnation, simplifying the overall process by preparing the Cr structure in advance rather than attempting to disperse Cr particles directly in molten Cu
Solution Approach 2:
The invention uses a sintered Cr body as an intermediary structure between the Cr powder and the final Cu-Cr composite. The sintered Cr body serves as a mediator that holds the Cr particles in a stable configuration, enabling controlled Cu infiltration and simplifying the manufacturing process compared to direct particle dispersion methods
3Strength
If infiltration method is used instead of solid phase sintering to reduce gas content and improve mechanical strength, then material density is improved, but the composition ratio between Cu and Cr cannot be freely selected
Solution Approach 1:
The invention segments the manufacturing process into two independent stages: first forming a sintered Cr body with desired composition and structure, then infiltrating Cu into the pre-formed Cr framework. This segmentation allows independent optimization of Cr composition (for electrical characteristics) and Cu content (for mechanical properties), restoring composition flexibility while maintaining infiltration method advantages
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 results in an electrode material with improved withstand voltage and current-interrupting capabilities, reduced oxygen content, and enhanced mechanical strength, while maintaining machinability, by refining and uniformly dispersing Cr and heat-resistant element particles within the Cu structure.
Implementation Method 1
sintering a mixed powder containing one part by weight of a powder of at least one kind of a heat resistant element selected from the group consisting of Mo, W, Ta, Nb, V and Zr and up to four parts by weight of a powder of Cr to obtain a solid solution where the heat resistant element and Cr are dissolved
Implementation Method 2
a Cu infiltration step of infiltrating the sintered body with Cu, wherein in the provisional sintering step the powder of at least one kind of the heat resistant element has an average particle diameter of 2-20 μm
Implementation Method 3
a provisional sintering step of sintering a mixed powder containing one part by weight of a powder of at least one kind of a heat resistant element selected from the group consisting of Mo, W, Ta, Nb, V and Zr and up to four parts by weight of a powder of Cr to obtain a solid solution where the heat resistant element and Cr are dissolved
Data Source
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Figure 3(a)~3(b)
AI summary
A method for producing an electrode material wherein particles containing Cr are miniaturized and uniformly dispersed and Cu portions, which serve as a highly conductive component, are also miniaturized and uniformly dispersed. This method for producing an electrode material involves: a mixing step (S1) for mixing a heat resistant element powder and a Cr powder; a provisional sintering step (S2) for obtaining a solid solution of the heat resistant element and Cr by provisionally sintering the mixed powder; a pulverizing step (S3) for obtaining a solid solution powder of the heat resistant element and Cr by pulverizing the solid solution of the heat resistant element and Cr; a molding step (S4) for molding the solid solution powder; a main sintering step (S5) for obtaining a sintered body (skeleton) of the heat resistant element and Cr by subjecting the thus-obtained molded body to main sintering; and a Cu infiltration step (S6) for infiltrating the sintered body of the heat resistant element and Cr with Cu.