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Fabrication And Properties Of Silver Based Multiwall Carbon Nanotube Composite Prepared By Spark Plasma Sintering Method

Lis M., Wrona A., Mazur J., Dupont C., Kamińska M., Kopyto D., Kwarciński M.

Archives of Metallurgy and Materials

2015

Vol. 60, iss. 2B

1351--1355

The paper presents results of investigations of the obtained nanocomposite materials based on silver with addition of multiwall carbon nanotubes. The powder of carbon nanotubes content from 0.1 to 3 wt. % was produced by application of powder metallurgy methods, through mixing and high-energetic milling, and also chemical methods. Modification of carbon nanotubes included electroless deposition of silver particles on the carbon nanotube active surfaces and chemical reduction with strong reducing agent – sodium borohydride (NaBH4). The obtained powder mixtures were consolidated by SPS – Spark Plasma Sintering method. The formed composites were subjected to tests of relative density, electrical conductivity and electro-erosion properties. Detailed examinations of the structure with application of X-ray microanalysis, with consideration of carbon nanotubes distribution, were also carried out. The effect of manufacturing methods on properties of the obtained composites was observed.

Synthesis and characterisation of a nano-silver soldering paste obtained by NaBH4 reduction in presence of PVP

Dupont C., Sobota J., Głuchowski W., Wrona A.

Archives of Materials Science and Engineering

2013

Vol. 64, nr 2

237--242

Purpose: In this work, a new synthesis has been investigated to obtain a nano-silver soldering paste capable of sintering at low temperature. Design/methodology/approach: The nano-silver soldering paste has been obtained by chemical reduction, with sodium borohydride (NaBH4) in presence of polyvinylpyrrolidone (PVP). The paste has been used for bonding two Cu plates. The Cu-Ag-Cu joint was obtained by sintering the nano-silver paste at a temperature ranging from 200°C to 400°C, in air, under a normal load of 5 MPa. The shear strength of the joints has been measured. Findings: The Ag particles obtained by this method are spherical, with an average size of 100 nm which allow sintering at low temperature. A sintering temperature of 250°C is sufficient for bonding two copper plates and the paste with an Ag/PVP weight ratio of 2.45 offers the best results. However, a maximum shear strength of 51 N is measured which is lower than the literature reference for large Cu chips bonding. Research limitations/implications: Other Ag/PVP ratio should be investigated in order to minimise the presence of impurities introduced by the reactant. Investigations concerning the Cu surface treatment, for improving the shear strength of the bond, should also be realised. Practical implications: The nano-silver soldering paste cannot be applied, yet, in electronic industry. Further improvements are required. Originality/value: The synthesis of nano-silver soldering paste by chemical reduction with NaBH4 in presence of PVP can be realised in one-step, at room temperature, which is important to minimise the synthesis costs.