Cu-Mo-Cr Electrode Material Sintering Process
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Solution Overview
Problem
Existing methods for producing copper-molybdenum-chromium (Cu-Mo-Cr) electrode materials for vacuum interrupters are costly and result in electrode materials with internal pores, leading to poor brazing and reduced electrical characteristics due to diffusion of Cr into Mo and contraction during sintering, which affects the manufacturing cost and usability of the materials.
Innovation Solution
A method involving the mixing of Cu powder, Cr powder with a particle diameter of 150 µm or less, and a refractory metal powder, followed by press molding and sintering in a non-oxidizing atmosphere at 1030°C to 1045°C, ensuring a high filling ratio and dispersion of Cr and refractory metal solid solutions in the Cu phase, thereby reducing pore formation and enhancing electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a provisional sintering step is conducted to produce Cu-Mo-Cr electrode material, then the electrical properties such as current-interrupting capability and dielectric strength are improved, but the manufacturing cost increases due to the time-consuming process and controlled pulverization atmosphere requirements
Solution Approach 1:
The patent extracts and eliminates the provisional sintering step from the traditional two-step process. By directly sintering the mixed powder of Cu, Mo, and Cr at 1000-1100°C without preliminary sintering, the method removes the source of Cr diffusion and pore formation while maintaining electrical properties, thereby reducing manufacturing cost and process complexity
Solution Approach 2:
The patent performs preliminary mixing of Cu powder, Mo powder, and Cr powder in specific proportions (Cu: 70-85 wt%, Mo: 5-20 wt%, Cr: 2-10 wt%) before sintering. This preliminary uniform distribution of particles prevents Cr diffusion during sintering and eliminates the need for controlled pulverization atmosphere, reducing manufacturing cost while maintaining reliability
2Ease of manufacture
If high melting point metal powders are simply mixed and press sintered to produce electrode material, then the manufacturing process is simplified, but the electrode material contains many internal pores leading to poor brazing and reduced electrical characteristics
Solution Approach 1:
The patent changes the sintering temperature parameter to 1000-1100°C, which is below the melting point of Cr (1857°C) and Mo (2623°C). This temperature control prevents Cr diffusion into Mo particles while ensuring adequate sintering density, eliminating internal pores and improving brazing properties without complex process steps
Solution Approach 2:
The patent creates a composite material structure by uniformly distributing fine Cr particles (average diameter 10 µm or less) and Mo particles (average diameter 20 µm or less) within the Cu matrix before sintering. This composite structure prevents pore formation during sintering while maintaining electrical characteristics, achieving both process simplicity and product reliability
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
This approach results in electrode materials with improved brazing properties and increased withstand voltage capability, reducing manufacturing costs and enabling the production of high-quality electrode contacts with a filling ratio of 90% or more, suitable for vacuum interrupters with enhanced electrical performance.
Implementation Method 1
a sintering step of sintering the molded body obtained by the molding step, the sintering step being conducted in a non-oxidizing atmosphere at a temperature of 1030°C to 1045°C
Data Source
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Figure 3~4(b)
AI summary
An electrode material obtained by press molding a mixed powder where a Cu powder, a Cr powder and a refractory metal powder (for example, a Mo powder) are mixed and then sintering the thus-obtained molded body in a non-oxidizing atmosphere at a temperature that is not higher than the melting point of Cu. As the Cr powder to be mixed in the mixed powder, a Cr powder wherein the volume-based relative particle amount of particles having particle diameters of 40 µm or less is less than 10% is used. The Cr powder is mixed in the mixed powder in an amount of 10-50% by weight, while the refractory metal powder is mixed in the mixed powder in an amount of 1-10% by weight.