# Graphene-Enhanced CuW Composites for High-Voltage Circuit Breaker Electrical Contacts
## 1 Introduction  
Electrical contacts, being the pivotal component of high-voltage circuit breakers, directly influence their breaking capacity [1; 2; 3]. Copper-tungsten (CuW) composites, as a prototypical two-phase pseudo-alloy, integrate the high conductivity and thermal conductivity of copper with the exceptional strength and arc ablation resistance of tungsten. Owing to these advantageous characteristics, CuW composites, especially CuW80 (80 wt.% W content), are extensively utilized as electrical contacts in high-voltage circuit breakers [4; 5; 6; 7; 8].  
However, with the development of New Power System, the increasingly serious problem of over-standard short-circuit current leads to higher requirements for the breaking capacity of high-voltage circuit breakers [9; 10; 11; 12; 13; 14]. Traditional CuW composites find it difficult to meet the higher requirements of electrical contacts for comprehensive properties such as conductivity and arc ablation resistance. It is urgent to improve the comprehensive properties of CuW composites through process optimization or doping modification to meet the needs of higher voltage grade circuit breakers.  
To improve the properties of CuW composites, doping modification by the third component such as rare earth elements, rare earth element oxides (La\({}_{2}\)O\({}_{3}\), ThO\({}_{2}\), CeO\({}_{2}\)) or ceramic materials (Al\({}_{2}\)O\({}_{3}\), Y\({}_{2}\)O\({}_{3}\)), and other third phase elements was always used. By doping modification, the thermochemical stability of CuW composites was improved through the uniform dispersion of additive. However, the addition of the third componentmay bring some other problems, such as the significant decrease in electrical conductivity [15; 16; 17; 18; 19; 20; 21; 22]. It is unable to achieve the coordinated improvement of the comprehensive performance. Graphene, as a new two-dimensional carbon material rising in recent years, has remarkable advantages such as high electrical conductivity, high thermal conductivity, high specific surface area, light weight, and high strength [23; 24; 25; 26; 27; 28; 29; 30]. It will be an ideal material for the modification of CuW composites, and is expected to bring more excellent comprehensive properties as an additive modification phase.  
In previous studies, [PERSON] et al. [18] systematically investigated the arc ablation behavior of Cu-W alloys with different W contents in an atmospheric environment. [PERSON] and [PERSON] et al. [19; 20] investigated the physical and mechanical properties of W-Cu alloys doped with rare-earth oxides La\({}_{2}\)O\({}_{3}\). [PERSON] et al. [21] prepared W-Cu alloys with an individual addition of WC and CeO\({}_{2}\) particles, and found that a good combination of the hardness, electric conductivity, and dielectric strength of W-Cu alloys can be obtained with proper amount of WC or CeO\({}_{2}\) addition into the tungsten skeleton. [PERSON] et al. [22] found that the hardness and density of copper-based contact materials increase with adding proper amount of Y\({}_{2}\)O\({}_{3}\). In this paper, graphene-enhanced CuW composites and electrical contacts for a high-voltage circuit breaker were prepared innovatively using integrated vacuum infiltration technology. Different from rare-earth oxides or ceramic particles doping modification, graphene would not affect the electrical and thermal conductivity properties of CuW composites when used as an additive [30]. The innovative graphene-enhanced CuW electrical contacts passed type testing and realized engineering application relying on the high-voltage circuit breaker for the first time, which provides a new route for the development and application of high-performance CuW electrical contacts.