Detonation Synthesis and Friction-Wear Test of Carbon-Encapsulated Copper Nanoparticles

Abstract

Carbon-encapsulated copper nanoparticles were successfully synthesized by preparing an explosive mixture consisting of cupric citrate xerogel, oleic acid, and cyclonite under three operating conditions in the explosion vessel with nitrogen and argon as protective gases. Results obtained through the characterization of the detonation products by X-ray diffraction, transmission electron microscopy, and the four-ball friction test. It showed that the molar ratio of copper to carbon in explosive mixtures exerted considerable influence on the synthesis of carbon-encapsulated copper nanoparticles. The synthesis effect of carbon-encapsulated copper nanoparticles was better when the molar ratio range no more than 0.031. In this range, the particles showed good dispersion and high degree of graphitization of the carbon shell, grain size of approximately 10–30 nm, and carbon shell thickness of approximately 2–3 nm. When the ratio exceeded 0.031, carbon-encapsulated copper nanoparticles were not synthesized, and the products included exposed copper particles and amorphous carbon. A new type of the explosive mixture is presented in the paper, namely, the mass ratio of {Cu [CO(NH2)2]2}(NO3)2, Cu 2} to oleic acid, sorbitan stearate and RDX being 16:27:10:76, suitable for synthesis of carbon-encapsulated copper nanoparticles. After adding carbon-encapsulated copper nanoparticles, the friction coefficient of lubricating base oil decreased with the increase in carbon-encapsulated copper nanoparticle dosage, and the anti-wear ability also increased to varying degrees. To illustrate, when carbon-encapsulated copper nanoparticle dosage was 1 wt%, anti-wear ability was improved by 10.6 %.