ACTIVITY PARAMETERS OF COPPER NANOPOWDER AFTER LONG STORAGE IN CONDITIONAL-HERMETIC PACKAGE

• Main Authors: Dmitriy V. Tikhonov, Alexander P. Ilyin, Ekaterina A. Bespalova
• Format: Article
• Language: Russian
• Published: Tomsk Polytechnic University 2019-05-01
• Series: Известия Томского политехнического университета: Инжиниринг георесурсов
• Subjects: nanopowder; copper; electrical explosion; parameters of activity; thermal effect; oxidation start temperature; storage; air; maximum oxidation rate; enthalpy of oxidation
• Online Access: http://izvestiya.tpu.ru/archive/article/view/282/190

Relevance of the research is related to determination of parameters of copper nanopowders series activity after 16 years storage in an air-tight container. The main aim of the research is to determine by the experiment four parameters of chemical activity of copper nanopowders series and to establish the laws of change in these parameters after long storage of these nanopowders in the air-tight container. Object: copper nanopowders, produced by wire explosion technique in argon atmosphere. Methods. Phase content of copper nanopowders series was determined «Shimadzu» XRD/700 difractometer. Sizes and shapes of nanoparticles were investigated by reflection electron microscopy JSM-750FA Jeol. Specific surface areas of nanopowders were determined by means of low temperature nitrogen adsorption (BET). Metal copper content was determined by thermogravimetry after heating up to 1250 °C with heating speed 10 °/min. Activity of copper nanopowders was characterized by four parameters of activity. Results. After storage (16 years) of copper nanopowders in the air-tight container, some samples became pyrophoric: their oxidation temperature dropped to 19 and 16 °C. At the same time, there are samples with oxidation start temperature of 188 and 190 °C. Maximum oxidation rate of copper nanopowders was 32,3×10–4 mg/s, and the minimum only 5,2×10–4 mg/s. When copper nanopowders are heated to 650 °C, the enthalpy of their oxidation for the most part of the samples is ≈1500 kJ/mol. The content of metallic copper in nanopowders of the samples ranged from 46,7 to 73,5 wt. %. The absence of correlation dependencies between the conditions of electric explosion and the parameters of activity is apparently related to the multiparameter dependence of an oxide shell formation on copper particles: the conditions of passivation are significant. A feature of copper nanopowders is the impossibility of forming a protective film on the particle surface: oxidation product is crystalline CuO phase and roentgenomorphic Cu2O phase in the form of 4–6 nm clusters.