World Journal Of Engineering
MICROSTRUCTURE AND MECHANICAL PROPERTIES OF CERMIC-METAL
COMPOSITES OBTAINED BY PRESSURE INFILTRATION
Paulina Chabera1, Anna Boczkowska2, Artur Oziębło3, Zbigniew Pakieła4, Krzysztof J.
Kurzydłowski5
1,2,4,5 Warsaw University of Technology, Faculty of Materials Science and Engineering, Woloska Str 141, 02-507
Warsaw, Poland
3 Institute of Ceramics and Construction Materials, Postępu Str 9 , 02-676 Warsaw, Poland
Corresponding author e-mail: pachabera@gmail.com
infiltration (GPI) in an autoclave (T=7000C, p=4
MPa, t=5’) designed and built at the Department of
Materials Technology, Silesian University of
Technology (PL) [4,5]. As a results six types of
INTRODUCTION
In last years the increase of interest in
ceramics matrix composites, mostly infiltrated by
light metal is observed. A lot of works concerning
methods of fabrication of composite with percolation
of phases can be found. The composite’s
microstructure
is
characterized
by
two
interpenetrating phases of ceramic and metal [1-2].
In this study, the effect of the method of
fabrication of porous ceramics Al2O3 by cast
aluminium alloy EN AC-AlSi11 (AK11) on
composite compressive strength, hardness and
Young’s modulus was shown. Also specific surface
fraction of the interphase boundaries affect on
mechanical properties and energy absorption of
ceramics-metal composites.
The obtained microstructure with percolation
of ceramic and metal phases gives the composites
high mechanical properties together with the ability
to absorb the strain energy.
composites were obtained.
EXPERIMENTAL METHODS
The microstructure of these composites was
studied with Scanning Electron Microscopy
(HITACHI
S-2600N)
and
quantitatively
characterized using image analysis. Also X-ray
tomography type SkyScan 1174 was used for
microstructure characterized. Such parameters as
volume fraction of both phases and distribution of
pores were calculated. The specific surface fraction
of the interphase boundaries (Sv) was determined
using by Micrometer program. The Brinell hardness
tests were performed. Also the compression tests
were carried out using machine Zwick 250 with the
application of Digital Image Correlation (DIC)
method. The DIC method allowed to determine the
Young’s modulus. For the full identification of
phases on the boundaries and inside the metallic
phase X-ray and TEM examinations were done.
MATERIALS
The ceramic preforms were manufactured by
sintering of Al2O3 powder. Chemical composition of
aluminum oxide was Al2O3 (99,8wt.%), CaO
(0,02wt.%), SiO2 (0,04wt.%), MgO (0,04wt.%),
Fe2O3 (0,03wt.%), Na2O (0,07wt.%). For each
ceramics preforms porosity was at the same level,
approximately 70vol.%. Porous aluminum oxide
preforms were formed by method of copying the
cellular structure of the polymer matrix [3]. The three
types of polyurethane sponges, differing in the
density and size of pores, were exploited: 45, 60 and
90 porous to the inch (ppi). This results in fabrication
of preforms with the pore sizes varied from 150 to
500 µm [3].
RESULTS
The results of X-ray tomography proved very
good infiltration of the pores by the metal. The
composites obtained from preforms with the smallest
pores by infiltration with aluminium alloy exhibit the
smallest residual porosity (<1%). Using gas-pressure
infiltration as a fabrication methods of composites
results in the higher degree of residual porosity.
SEM investigations confirmed that pores are almost
fully filled by aluminium alloy.
The effect of method of the infiltration on
mechanical properties is shown in table 1.
The composites were made by the
infiltration of ceramic preforms with the cast
aluminium alloy EN AC-AlSi11 (AK11). For
infiltration of ceramic preforms were applied a
pressure-vacuum infiltration on the Degussa press
(T=7200C, p=15 MPa, t=15’) (DP) and gas-pressure
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World Journal Of Engineering
The gas-pressure infiltration ensure the
highest mechanical properties and degree of
infiltration.
The mechanical properties of composites
depend on the specific surface fraction of the
interphase boundaries (Sv) and the degree of
infiltration. The composite obtain via infiltration of
ceramics preform with the smallest pores (150µm)
has the highest value of compressive strength,
hardness and Young’s modulus. It was found that the
energy absorption ability of a composites increases
treble with the growth of fraction of interphase
boundaries.
Due to combining ceramics and metal phases
the composites with higher mechanical properties
compared to porous ceramics can be obtained.
Moreover, such composites do not loose their
cohesion during compression, while ceramics
samples are totally broken.
It was proved that developed technology of
fabricating the composite material with the ceramics
matrix infiltrated by aluminium alloy ensures the
required microstructure, and moreover, obtained
composite materials can be applied in practice.
TABLE 1. Mechanical properties of Al2O3/ AlSi11
composites
Designation
Size of
Compressiv Young’s
of Al2O3/
pores of
Hardness
e strength
modulus
AlSi11
Al2O3
HB
[MPa]
[GPa]
composites preforms
Infiltration on Deguss Press
1-150_DP
150μm
88,8±4,2
254
51,2
2–350_DP
350μm
68,8±1,8
216
37,5
3-500_DP
500μm
57,8±0,7
150
11,5
Gas-pressure infiltration GPI
1-150_GPI
150μm
97,3±1,2
341
51,7
2–350_GPI
350μm
76,2±2,9
317
44,1
3-500_GPI
500μm
72,9±0,8
294
41,6
350
120
340
100
330
80
320
60
310
40
300
20
290
0
5
6
7
8
S v [1/m ]
9
10
REFERENCES
1. Binner J., Chang H., Higginson R., Processing of
ceramic-metal
interpenetrating
composites,
Journal of the European Ceramic Society, 29
(2009), 837–842.
2. Scherm F., Völkl R., Neubrand A., Bosbach F.,
Glatzel U., Mechanical characterisation of
interpenetrating
network
metal–ceramic
composites, Materials Science and Engineering,
A 527 (2010), 1260-1265.
3. Oziębło A., Jaegerman Z., Traczyk S., Dziubak
C., Porowata ceramika do wytwarzania
kompozytowych
materiałów
metalowoceramicznych metodą infiltracji ciśnieniowej
ciekłymi stopami aluminium, Szkło i Ceramika,
Rocznik 57 (2006).
4. Dolata-Grosz A., Dyzia M., Śleziona J.
“Manufacture and structure of infiltrated of Alcarbon fibres composites”, Archives of
Mechanical Technology and Automation Vol. 30,
no 3, pp 11-18, 2010.
5. Dolata-Grosz A., Dyzia M., Śleziona J. Structure
of Al-CF composites obtained by infiltration
methods, Archives of Foundry Engineering, Vol.
11, Special Issue 2, pp. 23-28, 2011.
HB , E [G P a],
E nerg y [MJ /m2]
R c [MP a]
Composites fabricated by the gas-pressure
infiltration of the preforms with the smallest pores
size are characterized by the highest hardness,
compressive strength and Young’s modulus.
The image analysis has been used to evaluate
the specific surface fraction of the interphase
boundaries (Sv). Presented results of the studies show
the effect of the surface fraction of the interphase
boundaries of ceramics-metal on composite
compressive strength, hardness and Young’s modulus
(figure 1). The hardness HB, compressive strength,
the Young’s modulus and energy absorption increase
with the increase of the Sv parameter.
Compressive
strength
Hardness HB
306,5/5
Young's Modulus
Energy absorption
Fig. 1. Effect of the specific surface fraction of the
interphase boundaries on mechanical properties of
Al2O3/ AlSi11composites fabricated by Gas-pressure
infiltration ceramic preforms
CONCLUSIONS
Ceramic-metal composites, obtained via
pressure infiltration of porous Al2O3 ceramics by cast
EN AC-AlSi11 (AK11)
aluminium alloy are
characterized by a large degree of filling up pores by
metal. As a result of the ceramics infiltration
composites of two interpenetrating phases are
fabricated. The obtained microstructure gives the
composites with high mechanical properties together
with the ability to absorb of the strain energy.
ACKNOWLEDGEMENTS
The studies were carried out within
PanCerMet project: „The passive protection of
mobile vehicles (air and land) against the influence of
AP bullets” No. of O R00 0056 07 financed by
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World Journal Of Engineering
National Centre for Research and Development
(Poland).
The authors would like to thank Doctor Anna
Dolata- Grosz from Silesian University of
Technology, Faculty of Materials Science and
Metallurgy for his scientific contribution and help in
fabricated
ceramic-metal
composites.
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