Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved International Review of Mechanical Engineering, Vol. 5, N. 2 Special Issue on Heat Transfer
323
Fig. 3. Photothermal radiomentry: amplitude over frequency values measured circles for sample MCNF1 in comparison to 2D modeling
dashed line
Fig. 4. Photothermal radiometry: phase over frequency values measured for sample MCNF1 circles vs. 2D modeling dashed line
The fitted measured values result in an in-plane thermal conductivity of k||
≈ 360 WmK and an out-of- plane thermal conductivity of k
⊥
≈ 1.2 WmK. This results in a huge anisotropy ratio of k|| k
⊥
=300.
IV. Conclusion and Outlook
In the present study the feasibility of producing anisotropic aligned carbon nanofibres in a copper matrix
by filtering and hot pressing was shown. The results of the performed photothermal radiomentry measurements
did support this evidence of 2D aligned CNF by a measured huge anisotropy ratio of in-plane and out-of-
plane thermal conductivities k|| k
⊥
=300. Using coating techniques in combination with the powder metallurgical
consolidation method of hot pressing this technique is suitable to produce homogeneously dispersed and
anisotropic aligned carbon nanofibre reinforced metal matrix composites.
Future work will include adapting this manufacturing technique to possible applications in the field of thermal
management, for example as heat spreading materials.
Acknowledgements
This work was financially supported under EU grant “INTERFACE” STRP NMP3-CT-2006-031712 of the
FP6 program and by the FFG Research Studio Austria RHP under contract 818649 as well as by MCST RI-
2006-006. The paper was presented at the Powder Metallurgy
World Congress in Florence, Italy, 2010.
References
[1] N. Eustathopoulos, Dynamics of wetting in reactive metalceramic systems, Acta Metallurgica, Vol. 46, No.7, pp. 2319-2327, 1998.
[2] H. Weidmueller, T. Weissgaerber et al., Carbon-Nanofiber
Reinforced Cu Composites Prepared by Powder Metallurgy for Thermal Management of Electronic Devices, Materials Science
Forum Vols. 534–536, pp. 853–856, 2007. [3] R.B. Barclay, W. Bonfield, Carbon FibreNickel Compatibility,
Journal of Materials Science, Vol. 6, pp. 1076-1083, 1976. [4] Yu Naidich, G.A. Kolesnichenko, Investigation of the wetting of
diamond and graphite by molten metals and alloys V. Carbide- formation kinetics at the graphitemetallic melt interface, Powder
Metallurgy and Ceramics, Vol. 7, No. 2, pp. 139-141, 1968. [5] V. Brueser et al., Metallisation of carbon nanofibres by Physical
Vapour Deposition, conference proceedings, Proc. ISPC19 Conf., Bochum, Germany, 2009.
[6] J.M. Cordoba, M. Oden, Growth and characterization of
electroless deposited Cu films on carbon nanofibers, Surface and Coatings Technology, Vol. 203, Issue 22, pp. 3459-3464, 2009.
Authors’ information
1
RHP-Technology GmbH Co. KG, Seibersdorf, Austria
2
Vienna University of Technology, Austria
3
Leibniz Institute INP Greifswald, Germany
4
University Reims Champagne-Ardenne, GRESPI, France
5
IMA Engineering Services Ltd., Zejtun, Malta
M. Kitzmantel studied physics at the Vienna University of Technology in Austria and
received his master of science degree in 2007 in the field of nano-reinforced thermal management
materials. His current research is focused on powder
metallurgy for processing metal matrix composites and advanced material developments
involving interfacial interactions for improved thermal transfer. DI Kitzmantel is currently reading his PhD on thermal issues in
diamond metal matrix composites at the Vienna University of Technology.
V. Brüser studied chemistry at the Greifswald University in Germany and received the diploma
in 1991 in the field of phosphorescent materials. In 1991-1994 he worked as PhD student at the
Greifswald University and in 1997 he received his PhD Dr. rer. nat. The subject of his PhD
was the development of solid state gas sensors. His research is related to the plasma treatment of
powder surfaces for the development of composites, fuel cell catalysts, photocatalysts and sensors.
Dr. Brüser has been working at the Leibniz-Institute for Plasma Science and Technology in Greifswald since 2002. In 2006 he became the head
of the department for plasma process technology.
M. Chirtoc was born in Cluj-Napoca, Romania, on Aug. 3rd, 1952. He received his PhD degree
in molecular physics at the University of Cluj, Romania, in 1984.
His research field is the photothermal characterization of materials using modulated
laser excitation. His recent research focuses on thermal microscopy and thermophysical
properties of composites, nanofluids and multilayer structures. Prof. Chirtoc is member of the French Thermal Science Society SFT.
He was awarded the Prize of the Romanian Academy in 1987.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved International Review of Mechanical Engineering, Vol. 5, N. 2 Special Issue on Heat Transfer
324
M. Attard studied electrical engineering at the University of Malta and submitted his master
thesis in 2010 in the field of Thick Layer Copper Carbon Nanofibre Matrix Composites for
Thermally Loaded Applications. His current research on metal matrix composites
is in the investigation of cold forming methods for the manufacture of advanced materials for
heat transfer applications. Eur Ing. Attard is managing director at IMA Engineering Services Ltd.
which specialises in metal finishing and coating techniques in particular to coating of micro and nanofibres of alumina , tungsten carbide and
carbon nanofibres.
Special Issue on Heat Transfer, February 2011
Manuscript received and revised January 2011, accepted February 2011 Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
325
Thermal Diffusion Coating of Diamonds for Improved and Reliable Thermal Properties of Metal Diamond Composites
M. Kitzmantel
1,2
, E. Neubauer
1
, I. Smid
3
, C. Eisenmenger-Sittner
2
, P. Angerer
4
Abstract – Metal Diamond Composites exhibit promising properties for thermal management applications. A tailored design of the interface between the material partners is essential to exploit
the potential of the reinforcement. In this study a cost efficient and easy to apply coating technique based on thermal diffusion was investigated and thin nanometer to micrometer coatings of various
metals were successfully applied onto diamond powders. Besides the study of the diffusion process itself, the resulting layer thicknesses and interlayer compositions, the coated diamonds were
introduced in a metal matrix by hot pressing and the thermal properties of the composite were measured. Thermal conductivities above 600WmK and a coefficient of thermal expansion of 8-
10ppmK were achieved in such composites. In addition, thermo-mechanical stability was tested by thermal cycling under harsh conditions. Various sample geometries were produced to show the
benefits of PM processing which enables combining excellent thermal properties with good surface finish and complex shaping. Copyright © 2011 Praise Worthy Prize S.r.l. - All rights
reserved. Keywords:
Diamond MMCs, Heat Transfer Enhancement, Carbide Interlayers, Thermal Cycling
I. Introduction
