LEAD-FREE BRASS MADE BY DIRECT INJECTION OF CNT INTO SHOT SLEEVE OF HPDC MACHINE

Brasses belong to a group of copper-based alloys with a wide variety of important applications. Traditionally, lead was a necessary alloying element in brasses due to its ability to improve machining in terms of time and quality. Additional effect of lead is a wear reduce of machining tools. The main risk of using lead-containing brasses is lead`s toxicity for humans. Various stages of producing and machining of brasses may be harmful, so certain safety regulations are normally required, which is time and money expensive [1].

That`s why alternative technologies of producing lead-free brasses, using graphite, are of great interest. Carbon Nanotubes (CNTs) can be considered as ideal reinforcements, due to their high specific strength, thermal, electrical and mechanical characteristics.

In the present study brass (Cu-Zn)/carbon nanotubes (CNT) composites were produced by injection of CNTs in brass using high pressure die casting method. Current investigation demonstrates that more than 50 % efficiency of direct injection of CNT in the brass has been achieved. The inserted CNTs have been partially dispersed in the metal matrix. Furthermore the friction coefficient significantly decreases with an increase of the amount of CNT content in the examined Cu-Zn brass alloy. Thus, the machinability improvement as a result of CNT performance in the examined Cu-Zn brass alloy is expected.