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Physicochemical parameters effect on biosynthesis and properties of copper nanoparticles

Pawlowska Agnieszka, Kazmierczak Michal, Sadowski Zygmunt

Physicochemical Problems of Mineral Processing

2019

Vol. 55, iss. 6

1460--1466

Plant extract obtained from green tea was used for the synthesis of nanoparticles under anaerobic and aerobic conditions at various ratios of the copper solution to the extract used. The smallest nanoparticles were obtained at a ratio of 1:10. The nanoparticles showed the maximum negative value of the zeta potential around pH 6. An increase in the temperature of reaction caused a decrease in the negative zeta potential value. Synthesis under nitrogen atmosphere favours the formation of smaller copper nanoparticles.

Disruption of an Alumina Layer During Sintering of Aluminium in Nitrogen

Pieczonka T.

Archives of Metallurgy and Materials

2017

Vol. 62, iss. 2B

987--992

Aluminium oxide layer on aluminium particles cannot be avoided. However, to make the metal-metal contacts possible, this sintering barrier has to be overcome in some way, necessarily to form sintering necks and their development. It is postulated that the disruption of alumina layer under sintering conditions may originate physically and chemically. Additionally, to sinter successfully non alloyed aluminium powder in nitrogen, the operation of both types mechanism is required. It is to be noted that metallic aluminium surface has to be available to initiate reactions between aluminium and the sintering atmosphere, i.e. mechanical disruption of alumina film precedes the chemical reactions, and only then chemically induced mechanisms may develop. Dilatometry, gravimetric and differential thermal analyses, and microstructure investigations were used to study the sintering response of aluminium at 620°C in nitrogen, which is the only sintering atmosphere producing shrinkage.