Tungsten copper discrete contacts are made from tungsten and copper. Copper with excellent electrical and thermal conductivity, and tungsten with high density, hgh strength, high melting point and low coefficient of expansion, both immiscible intermetallic compound can not be formed. Tungsten copper materials combine the advantages of tungsten and copper, which with good thermal conductivity, density, thermal expansion coefficient, and therefore as an electrical contact material has been widely used. In recent years, with the continuous development of the electrical industry, copper tungsten contact material requirements are also further improved.
Preparation of tungsten copper discrete contacts mainly infiltration method, high temperature liquid phase sintering, mechanical alloying and sol-gel method. Tungsten copper discrete contacts material detachable bond strength depends directly on the powder size and uniformity. Studies have shown that tungsten powder particle size affect the contact material impediment to the emergence and development of cracks. Since the particles are sintered tungsten powder after a fine dispersion, if the contact material cracks and expansion, this process is bound to encounter fine tungsten powder particles produced bifurcation, crack propagation energy will be consumed gradually until it disappears completely. Therefore, tungsten powder particles finer more can prevent more dispersed generation and development of cracks, material strength and hardness are improved.
Contact is high and low voltage electrical switches, instrumentation important components responsible for the indirect circuit on and off, while the corresponding load circuit current task. Tungsten copper electrical contact material has been published since 1935, is widely used for automatic switching and universal circuit breaker, molded case circuit breaker.
As the voltage level of increase, tungsten copper contact materials research will encounter more and more new issues, such as electrical contact material life, anti-burning, anti-welding and so on. Tungsten copper electrical contact material for future research is divided into three areas: research material composition, the impact of main strengthening phase composition and content of the material properties; contact design research, design reasonable, elegant, compact electrical contact; preparing advantage concentrate explore new preparation process, in order to meet growing electrical tungsten copper electrical contact material requirements.