Porous electrically conductive materials produced by Spark Plasma Sintering and hot pressing of nanodiamonds

doi:10.1016/j.ceramint.2015.06.055

Ceramics International

Volume 41, Issue 9, Part B, November 2015, Pages 12459-12463

https://doi.org/10.1016/j.ceramint.2015.06.055 Get rights and content

Abstract

Nanodiamond particles are known to graphitize upon annealing gradually transforming into carbon onion structures. The goal of this work was to evaluate the potential of nanodiamond powders as a raw material to produce bulk porous electrically conductive materials by means of graphitization-accompanied Spark Plasma Sintering and hot pressing. Despite consolidation that occurred in parallel to graphitization, an increase in the specific surface area (up to 510 m² g⁻¹) relative to the nanodiamond powder (360 m² g⁻¹) was observed in compacts with high graphitization degrees. Compacts Spark Plasma Sintered at 1200 °C and hot-pressed at 1500 °C showed high electrical conductivities, which were one order of magnitude higher than those of the powders produced by nanodiamond graphitization and only 40–50 times lower than that of bulk graphite. Based on these results, a conclusion was made that consolidation of nanodiamonds by Spark Plasma Sintering and hot pressing can be used for developing porous electrically conductive materials with tailored specific surface area. A possible influence of electric current on graphitization of nanodiamonds during Spark Plasma Sintering was suggested.

Introduction

Nanodiamonds attract much attention as an interesting material with diamond structure and very fine particles that show variable surface chemistry, biocompatibility and non-toxicity [1]. The relative ease of production of nanodiamonds makes it tempting to consolidate them into a bulk compact with macro-dimensions. This puts forward a question whether the consolidated nanodiamonds can approach the quality of single crystal diamonds having the same size. Indeed, several studies have demonstrated attractive properties of the consolidated nanodiamonds [2], [3], [4], [5]. In those studies, the consolidation conditions were selected such that graphitization of nanodiamonds was brought to a minimum. This was enabled by the use of pressures of several GPa. At the same time, a possibility exists to consolidate nanodiamonds at relatively low pressures (several tens of MPa) in a compact of reasonable quality. Osswald et al. [6] used Plasma Pressure Compaction of nanodiamonds at 65 MPa to produce porous compacts, in which excessive graphitization was prevented.

Another attractive feature of nanodiamonds is their thermodynamically favored transformation into graphitic structures upon heating at low pressures. Due to an extremely small size of nanodiamonds, their behavior upon annealing is different from their micron-sized counterparts. Owing to graphitization, the stages of which are temperature-controlled, nanodiamonds are excellent precursors of carbon onion structures [7], [8], [9], [10], [11], [12], [13]. The structural changes occurring during annealing-induced graphitization and properties of the partially and fully graphitized products—specific surface area, pore size, electrical conductivity—have been widely studied. It has been observed that the specific surface area of graphitized nanodiamonds increases with increasing graphitization degree [8], [10], [13]. Nanodiamonds have been proven to work successfully as an additive to other porous carbon materials increasing the resultant specific surface area [14].

In this work, we were interested in graphitization-accompanied consolidation of nanodiamond powders. Consolidation of nanodiamonds into compacts of macro-dimensions could hinder the growth of the specific surface area characteristic of graphitization in the powder state, but at the same time could improve the electrical conductivity of the bulk material. An advanced powder consolidation method—Spark Plasma Sintering (SPS) [15], [16]—appears to be a suitable choice for efficient sintering of nanodiamonds. Sakamoto and Shida [17] reported SPS of an amorphous carbon powder containing sp²- and sp³ -bonded atoms. To our best knowledge, consolidation of nanodiamonds by Spark Plasma Sintering has not been attempted until now. Therefore, the goal of this work was to evaluate the potential of nanodiamonds as a raw material for manufacturing porous electrically conductive bulk materials by graphitization-accompanied consolidation. In this study, a nanodiamond powder was processed by Spark Plasma Sintering and hot pressing in order to reveal any possible unique effects involved in the two consolidation processes.

Section snippets

Materials and methods

Nanodiamonds (TU84-112-87, “Altai”, Biysk, Russia; particle size 5 nm, diamond content equal to or greater than 91%) were used in this study. Prior to consolidation, the powder was annealed at 800 °C for 1 h in vacuum.

Spark Plasma Sintering of the powders was carried out using a SPS Labox 1575 apparatus (SINTER LAND Inc.). A graphite die with an inner diameter of 10 mm and an outer diameter of 50 mm and tungsten punches with a diameter of 10 mm were used. The die wall was lined with a carbon foil.

Results and discussion

The morphology of the nanodiamonds annealed in vacuum at 800 °C is presented in Fig. 1. The primary particles of about 5 nm in size can be discerned, which form aggregates 100–150 nm in size. Indeed, unless special disintegration procedures are conducted, nanodiamond particles are known to be severely aggregated. Krüger et al. [18] distinguish large aggregates, which are easy to break, and core aggregates (100–200 nm in size), which are very tight and, therefore, hard to break. The stability of the

Conclusions

In this work, nanodiamond powders were consolidated by Spark Plasma Sintering and hot pressing. Consolidation of graphitizing particles into porous compacts led to the formation of electrically conductive materials having conductivity values one order of magnitude higher than those of the graphitization products of nanodiamonds in the powder state. Compacts Spark Plasma Sintered at 1200 °C and hot-pressed at 1500 °C showed electrical conductivities that were only 40–50 times lower than that of

Acknowledgments

This study is supported by the Russian Foundation for Basic Research, Research Project 15-33-20061 mol_a_ved.

The authors are grateful to Dr. Artem S. Ulikhin (ISSCM SB RAS) for performing the electrical conductivity measurements of the consolidated samples and Prof. Michail A. Korchagin (ISSCM SB RAS) for his help with annealing of the nanodiamond powder.

References (23)

G.N. Yushin et al.
Effect of sintering on structure of nanodiamond
Diam. Relat. Mater.
(2005)
S.V. Kidalov et al.
Thermal conductivity of sintered nanodiamonds and microdiamonds
Diam. Relat. Mater.
(2008)
A.S. Osipov et al.
Rapid sintering of nano-diamond compacts
Diam. Relat. Mater.
(2009)
S. Osswald et al.
Plasma pressure compaction of nanodiamond
Diam. Relat. Mater.
(2007)
V.L. Kuznetsov et al.
Onion-like carbon from ultra-disperse diamond
Chem. Phys. Lett.
(1994)
C. Portet et al.
Electrochemical performance of carbon onions, nanodiamonds, carbon black and multiwalled nanotubes in electrical double layer capacitors
Carbon
(2007)
Z. Qiao et al.
Graphitization and microstructure transformation of nanodiamond to onion-like carbon
Scr. Mater.
(2006)
M. Zeiger et al.
Understanding structure and porosity of nanodiamond-derived carbon onions
Carbon
(2015)
R. Orrù et al.
Consolidation/synthesis of materials by electric current activated/assisted sintering
Mater. Sci. Eng. R
(2009)
N. Sakamoto et al.
Diamond-like carbon sintered compacts formed by spark plasma sintering
Diam. Relat. Mater.
(2014)

A. Krüger et al.

Unusually tight aggregation in detonation nanodiamond: identification and disintegration

Carbon

(2005)

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Short communicationPorous electrically conductive materials produced by Spark Plasma Sintering and hot pressing of nanodiamonds

Abstract

Introduction

Section snippets

Materials and methods

Results and discussion

Conclusions

Acknowledgments

Diam. Relat. Mater.

Diam. Relat. Mater.

Diam. Relat. Mater.

Diam. Relat. Mater.

Chem. Phys. Lett.

Carbon

Scr. Mater.

Carbon

Mater. Sci. Eng. R

Diam. Relat. Mater.

Carbon

Short communication
Porous electrically conductive materials produced by Spark Plasma Sintering and hot pressing of nanodiamonds