Mechanical Processing of Cu-graphite powders mixtures and subsequentconsolidation.
Barbara Lasio1*, Francesco Torre 1, Roberto Orrù1, Giacomo Cao1, Marcello Cabibbo2, Francesco Delogu1
1 Dipartimento di Ingegneria Meccanica, Chimica, e dei Materiali, Università degli Studi di Cagliari, via Marengo 2, 09123 Cagliari, Italy2 Dipartimento di Ingegneria Industriale e Scienze Matematiche, Università Politecnica delle Marche, via Brecce Bianche 12, 60131 Ancona, Italy
Università degli Studi
di Cagliari
References:J.W. Kaczmar, K. Pietrzakb, W. Włosińskici, 2000, Journal of Materials Processing Technology, 106, Pp 58–67;F. Delogu, G. Gorrasi, A. Sorrentino, 2017, Progress in Materials Science, 86 Pp 75-126;
L.Y. Chen, J.Q. Xu, H. Choi, M. Pozuelo, X. Ma, S. Bhowmick, J. M. Yang, S. Mathaudhu, X. C. Li, 2015, Nature, 528 Pp. 539-549.S. Garroni, S. Soru, S. Enzo, F. Delogu, 2014, Scripta Materialia, 88, Pp 9–12;P. Baláž, M. Achimovičová, M. Baláž, P. Billik, Z. Cherkezova-Zheleva, J. M. Criado, F. Delogu, E. Dutková, E. Gaffet, F. J. Gotor, R. Kumar, I. Mitov, T. Rojac, M. Senna, A. Streletskiikl, K. Wieczorek-Ciurowam, 2013, Chemical Society Reviews, 42 Pp 7571-7637;http://multiphysics.lab.asu.edu/facilities.shtml; https://www.elvatech.com/en/catalog/materials/blending/good464?print=1; http://dir.indiamart.com/delhi/graphite-powder.html. Acknowledgements: Special thanks to Dr Roberta Licheri for the loving helpful support.
Results: Nanoindentation Mechanical Tests
Results: X-Ray Diffraction XRD
Results: TEM Micrographs
Fig.4 Nanoindentation test of MMCs sintered samples: a) hardness and b) elastic modulus of the samples with the addition of graphite during every step of BM, c) hardness and d) elastic
modulus variation of the sintered samples after four steps of BM and only one addition of graphite
Without addition of graphite in every step
With addition of graphite in every step
Fig.2 XRD of MMCs powders and sintered samples measured every step of milling and with the addition of graphite only at the first step: a) behaviour of crystalline size
compared to milling time b) XRD analysis of milled powders measured after every step of milling c)XRD analysis of bulk samples measured after every step of milling.
Fig.1 XRD of MMCs powders and sintered samples measured every step of milling with the addition of graphite during every step: a) behaviour of crystalline size
compared to milling time b) XRD analysis of milled powders measured after every step of milling c) XRD analysis of bulk samples measured after every step of milling.
Fig.3 TEM Micrographs of MMCs sintered samples a) after one step of milling and one addition of graphite, b) after two steps of milling and two additions of graphite and c) after three steps of milling and
three additions of graphite, d) after four steps of milling and four additions of graphite.
a) b) c)
a) b)
c) d)
30 40 50 60 70 80
I hkl Copper
X r
ay In
ten
sity / a
.u.
Scattering Angle / 2
Powder BM step 1+C3%
Powder BM step 2+C3%
Powder BM step 3+C3%
Powder BM step 4+C3%
30 40 50 60 70 80
Scattering Angle / 2
X r
ay Inte
nsity / a
.u.
I hkl Copper
BM step 1+C3%
BM step 2+C3%
BM step 3+C3%
BM step 4+C3%
10 15 20 25 30 35 40 45 5020
30
40
50
60
70
80
90
100
110
120
Cry
sta
llite
Siz
e / n
m
Ball Milling Time / h
CrySizeS
CriSizeP
a) b) c)
40 50 60 70 80
Scattering Angle / 2
BM Step1 +C 3 wt.%
BM Step2
BM Step3
BM Step4
X r
ay In
tensity / a
.u.
I hkl Copper
30 40 50 60 70 80
I hkl Copper
Scattering Angle / 2
X r
ay Inte
nsity / a
.u.
Powder BM step1+C3%
Powder BM step2
Powder BM step3
Powder BM step4
10 15 20 25 30 35 40 45 5020
30
40
50
60
70
80
90
Cry
sta
llite
Siz
e / n
m
Ball Milling Time / h
sintered
powdera) b) c)
Copper
Graphite(3 wt.%)
Ball MillingSPS
consolidation Bulk material
Experimental
Ball milling BMBall to powder ratio: 1,5:1
Milling Time: 12 h, 24 h, 36 h and 48 hRest Time: 30 min every hour
Spark Plasma sintering SPS:900°C
Thermal Ramp :100°C/minIsothermal Time:10 min
Cu+C 3% Samples+C 3%
First procedure: addition of graphite in every step
Second procedure: addition of graphite only in the first step
Samples+C 3%
Samples+C 3%
BM
SPS
BM
SPS
BM
SPS
BM
SPS
Cu+C 3% Samples Samples SamplesBM
SPS
BM
SPS
BM
SPS
BM
SPS
Experimental
The present research work addresses the fabrication of metal matrix composites (MMCs) by mechanical processing. In particular, Cu-graphite powder mixtures have been subjected to mechanical processing by ball milling under inert atmosphere to induce mutual
dispersion of the constituents. Then, powder has been consolidated by spark plasma sintering, and the obtained pellets subjected to nanoindentation to investigate the variation of mechanical properties with milling time and graphite content.
SampleH
AverageError
H
Asymptoticerror
Er
Averageerror
Er
Asymptoticerror
1 step
BM
+3%C
900°C
Sintered1.25 0.05 1.15 0.05 28 6 25 5
2 step
BM
900°C
Sintered1.15 0.05 0.95 0.1 26 4 15 5
3 step
BM
900°C
Sintered1.5 0.1 1.35 0.05 42 6 42 2
4 step
BM
900°C
Sintered1.5 0.1 1.35 0.05 45 5 40 2
SampleH
AverageError
H
Asymptoticerror
Er
Averageerror
Er
Asymptoticerror
1 step
BM
+3%C
900°C
Sintered
2.10.2 1.3 0.1 33 5 31 5
2 step
BM
+3%C
900°C
Sintered1.4 0.1 0.85 0.05 23 3 21 2
3 step
BM
+3%C
900°C
Sintered0.86 0.05 0.65 0.05 25 3 22 2
4 step
BM
+3%C
900°C
Sintered0.80 0.1 0.55 0.05 23 2 22 2
Without addition of graphite in every stepWith addition of graphite in every step
d)
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0.0
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H average
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rdn
ess / G
Pa
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stic m
od
ulu
s / G
Pa Er Average
Er Tendency
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rdn
ess / G
Pa
HAverage
HTendency
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stic M
odu
lus / G
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ErTendency