Friction Performance of SiCp/Cu Hybrid Materials with Compound
Additive
Yunlong Zhang, Wei Zhou
*
, Haifeng Zhang and Qingxiang Yang
Anyang institute of technology, Huang he street, Anyang city, P. R. China
Keywords: Cu matrix hybrid material, Rare earth oxides, Coefficient of friction
Abstract: Copper alloy material had excellent electrical and thermal characteristics, but its poor wear resistance and low
hardness limited its wider application. So it was necessary to improve wear resistance of copper alloy. In this
paper, compound additives La
2
O
3
/Al
2
O
3
/CeO
2
were introduced into SiCp/Cu composites and hot-press
sintering method was executed to synthesize SiCp/Cu composites. The influence of rare earth oxides on the
phase constitution, micro structure and coefficient of friction of SiCp/Cu composites were investigated.
1 INTRODUCTION
Metal composites were developed into prime
candidate as functional materials. Metal-ceramics
composites exhibited superior performance such as
high specific strength, high elastic modulus and wear
resistance. Copper alloy were utilized as functional
materials with high thermal electrical properties
(Wang, 2011). However, the poor wear resistance
limited wider engineering application. Some ceramic
particles were used as reinforcement, such as metal
carbides (WC, SiC, TiC), metal nitrides (TiN, Si
3
N
4
),
metal borides (ZrB
2
, WB, TiB
2
) and metal oxides
(Al
2
O
3
, ZrO
2
). SiC particles were utilized in the Cu
matrix considering the special properties of SiC
p
on
account of high hardness, good wear, low density
(Dhokey, 2008). So SiC
p
/Cu composites were
developed as functional material due to their
excellent electrical and thermal conductivity, good
wear resistance (Zhang, 2008). At present, more
reports on SiC
p
/Cu composites were widespread (Zhu,
2007). Copper-based composites reinforced with
15-35wt.% SiC were fabricated by mechanical
alloying, so an increase in milling time and SiC
content (up to 25 wt.%) lead to a higher hardness of
Cu matrix materials due to homogenization of
microstructure and refinement of reinforcing
particles (Perumal, 2015). The effect of SiC content
and particle size on the density, hardness and
electrical conductivity were investigated (Peng,
2012). The structure and particle size of copper based
composite reinforced with a high content (15-35wt%)
of silicon carbide and prepared by mechanical
alloying in the high energy planetary mill
(Prosviryakov, 2013). However, the reports about
addition of rare earth oxides to SiC/Cu composites
were relatively scarce. In this work,
La
2
O
3
/Al
2
O
3
/CeO
2
were introduced into SiC
p
/Cu
composite. The density, phase constitution, micro
structure and coefficient of friction of SiC
p
/Cu
composites were investigated.
2 EXPERIMENTAL PROCESS
The initial materials were domestic copper powders
(D
50
=38µm), SiC powder (D
50
=38.5µm), Al
2
O
3
powders (D
50
=0.5µm) and La
2
O
3
powders
(D
50
=0.5µm). The initial powders were mixed in
accordance with the composition ratio designed in
Table 1 in which mass ratio of Al
2
O
3
and La
2
O
3
was
1:3. The content of CeO
2
was about 2wt.%. For
comparison specimen S5 without compound
additives was also studied. The initial powders were
mixed by ball-milling machine. The milling was
320rpm for 8h. Before sintering process, the mixture
was cold pressed into a cylindrical compact in a die of
40mm in diameter with pressure of 200MPa. SiC
p
/Cu
composites were sintered in a graphite die at 840℃
for 1h in hot-press sinter furnace with argon gas and
heating rate was about 30℃/min. Density measure
was carried out according to Archimedes principle.
Microstructure of composites was observed by SEM.
Phases constitution were analysized by X-ray(Bruker
Zhang, Y., Zhou, W., Zhang, H. and Yang, Q.
Friction Performance of SiCp/Cu Hybrid Materials with Compound Additive.
DOI: 10.5220/0008186100930096
In The Second International Conference on Materials Chemistry and Environmental Protection (MEEP 2018), pages 93-96
ISBN: 978-989-758-360-5
Copyright
c
2019 by SCITEPRESS – Science and Technology Publications, Lda. All rights reser ved
93
D8, Germany). The coefficient of friction of SiC
p
/Cu
composites were measured by SFT-2M type pin plate
friction and wear tester. The friction pair was GCr15
steel balls with a diameter of 6mm. Test parameters:
linear velocity is 200r/min, rotation radius was 3mm,
the load was 200g and the friction time was 600
seconds. S1, S2, S3, S4 represented SiC
p
/Cu
composites with different compound additive and S5
represented SiC
p
/Cu composites without compound
additive after friction experiment.
Table 1: Designation of SiCp/Cu materials (wt.%)
Designation
Cu
SiC
La
2
O
3
Al
2
O
3
CeO
2
S1
75.2
18.8
3
1
2
S2
73.6
18.4
4.5
1.5
2
S3
72
18
6
2
2
S4
70.4
17.6
7.5
2.5
2
S5
80
20
0
0
0
3 RESULTS AND DISCUSSION
Figure 1: XRD pattern of SiC
p
/Cu composites with
different compound additive.
XRD pattern of SiC
p
/Cu composites with different
compound additive was showed in Figure 1, Cu and
SiC peaks were detected as main phase, and La
2
O
3
was formed as trace phase. Other phase such as Al
2
O
3
and CeO
2
was not found in the SiC
p
/Cu composites.
The intensity of diffraction peaks of SiC and Cu
phase was not obvious even if compound additive
content was different. Copper was main crystal phase
and its diffraction peak corresponds to the standard
card of copper synthesis (JCPDS 04-0836). The
diffraction peak of 6H-SiC standard card (JCPDS
29-1131). The intensity of diffraction peaks of La
2
O
3
phase increased as the content of compound additive
content was higher.
Figure 2 revealed density of SiCp/Cu composites
with different content of compound additive. From
the data of the density, the density varied from
5.73~6.05g/cm
3
. As the total content of the
compound additive was beyond 8%, ( La
2
O
3
> 4.5%),
the density reduced due to more porosity and defects.
The density variation was not distinct. For improving
the density, too high or low additive was unsuitable.
Especially when La
2
O
3
content was about 4.5%, the
density was higher.
2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0
5.5
5.6
5.7
5.8
5.9
6.0
6.1
6.2
6.3
6.4
Density (g/cm
3
)
La
2
O
3
content (%)
Figure 2: Density of SiC
p
/Cu composites with different
content of compound additive.
The microstructure of SiC
p
/Cu composites with
different content of compound additive was listed in
Figure 3 a), b), c) and d) represented S1, S2, S3, S4
for SiC
p
/Cu composites with different compound
additive. White particles were SiC
p
and grey part was
Cu matrix. Moreover, Cu matrix was continuous and
no obvious hole appeared. It was difficult to
distinguish distribution variation of SiC
p
in the Cu
matrix, considering that proportion of SiC introduced
in the composition does not change significantly.
Figure 4 showed high magnification SEM photos
of S2 and S5 specimen. As the compound additives
were introduced into the SiC
p
/Cu composites, the
interface was more clear and more tightly integrated
between SiC and Cu matrix (shown in Figure 4a) As a
contrast, more defects and holes were found on the
interface between SiC and copper of SiC
p
/Cu
composites without compound additive. So the
introduction of composite additives with appropriate
content can improve interfacial adhesion between
SiC and copper matrix. The SiC particle were
distributed uniformly in the Cu matrix (shown in
Figure 4c) For all experimental specimens, SiC
particles was distributed uniformly in the Cu matrix.
MEEP 2018 - The Second International Conference on Materials Chemistry and Environmental Protection
94
Figure 3: Microstructure of SiC
p
/Cu composites with
different content of compound additive. a), b), c) and d)
represented S1, S2, S3, S4.
Figure 4: High magnification SEM photos of S2, S5 and S4
specimen. a), b) and c) represented S2,S5 and S4.
Figure 5 showed friction coefficient of SiC/Cu
materials with different content of compound
additive. As a comparison, friction coefficient of S5
was about 0.6~0.7. In comparison, friction coefficient
of SiC/Cu materials decreased significantly when
compound additive was introduced into SiC/Cu
materials. For four different SiC/Cu hybrid materials,
friction coefficient varied between 0.08~0.18.
Especially, when content of additive La
2
O
3
was
4.5%, its friction coefficient was about 0.07~0.09.
a)
d)
c)
b)
b)
interface
interface
c)
a)
Friction Performance of SiCp/Cu Hybrid Materials with Compound Additive
95
The friction coefficient of SiC/Cu composites
without compound additive was high. The addition of
compound additive played an important role, so it
effectively relieved plastic deformation of Cu matrix
during the friction process and improved wear
resistance, thus the abrasion resistance improved.
0 30 60 90 120 150 180 210 240 270 300 330 360
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
S5
S4
S3
S2
S1
Coefficient of friction
Time （ s）
Figure 5: Friction coefficient of SiC/Cu materials with
different content of compound additive.
4 CONCLUSIONS
SiC
p
/Cu composites were fabricated by hot-press
sinter method. The introduction of compound
additive played an important role on the friction
coefficient. Micron SiC
p
were distributed uniformly
in the Cu matrix. Compared with SiC
p
/Cu without
compound additive, friction coefficient of SiC
p
/Cu
materials with compound additive was low, so it
meant that SiC
p
/Cu materials with moderate
compound additive had better wear resistance.
ACKNOWLEDGEMENTS
Authors thank for fund support by science and
technology research projects from Anyang city (
project " thermal conductivity behavior research of
copper matrix hybrid materials with
wear-resisting/low expansion for aviation electric
contact field”),scientific research projects in
education department of Henan province
(No.18A430006), Higher education teaching reform
research and practice project for Henan Province (No.
2017SJGLX117), the scientific research project from
Anyang institute of technology (No. BSJ2017007,
BSJ2018018). Meanwhile, Part of the data in this
paper was provided by Key laboratory of Aerocraft
Simulation Design and Airborne Equipment of
Anyang City.
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