effect of nanoparticle addition to the mechanical proper- ties of composites from carbon and basalt fiber [21] and
different filler fibers [22–25]. However, very few studies have been carried out on the combination of carbon and
basalt fiber laminates.
In this work, we investigated the tensile properties of carbon- and basalt fiber-laminated composites, specifi-
cally focusing on the effect of the number of basalt fiber layers and arrangement position on the carbon fiber com-
posite laminates. The aim of this work was to assess the suitability of basalt fiber as an effective competitor of glass
fiber for the reinforcement of composites. Tensile tests were carried out. The failure surfaces of the composites
were analyzed by scanning electron microscopy SEM.
2 Experimental
2.1 Materials
In the present study, we used plain woven carbon fiber C120-3K; fabric weight = 200 ± 10 gm
2
; fabric thickness = 0.25 ± 0.02 mm purchased from Hyun Dai
Fiber Co. Ltd. Korea, and plain woven basalt fiber EcoB4 F210; fabric weight = 210 ± 10 gm
2
; fabric thick- ness = 0.19 ± 0.20 mm provided by Secotech Korea.
The resin matrix used was a modified bisphenol A epoxy resin HTC-667C; specific gravity = 1.16 ± 0.02;
viscosity = 1.2 ± 0.5 kgm.s with a modified aliphatic amine hardener and was supplied by Jet Korea Co. Korea.
2.2 Composite fabrication
The panels of laminates were manufactured by a vacuum- assisted resin transfer molding VARTM process. VARTM is
an adaptation of the resin transfer molding RTM process that exploits vacuum pressure of 101.32500 kPa to draw
off resin to the impregnate preforms. VARTM presents many benefits in composite fabrication such as low cost,
low void contents, and stable product thickness [22, 26, 27]. The schematic of the present VARTM process is shown in
Figure 1. In this work, a bronze plate with dimensions of 300 mm × 300 mm was prepared and oiled with a liquid wax
for safe release on the top of plate. Sealant tape was then placed around the plate. The carbon and basalt fibers were
both cut with a dimension of 250 mm × 250 mm and arranged on the mold according to the laminate design. Next, epoxy
resin with a hardener mixture ratio of 5:1 after degassing in vacuum desiccators at -70 cmHg for 40 min, was directly
Figure 1 Schematic layout of VARTM: 1 bronze plate, 2 laminate fiber, 3 release films, 4 breather net, 5 vacuum tube, 6 plastic
bag, and 7 sealant tape.
Table 1 Properties of CFRP, BFRP, and hybrid composite with different numbers and arrangement positions of basalt fiber into
the carbon fiberepoxy.
Sample Sample
code Number of fibers
Basalt fiber fraction wt
CF BF
CFRP C
10 62
BFRP B
– 10
61.9 C
4
B
1
C
5
B1 9
1 6.19
C
4
B
2
C
4
B2 8
2 12.4
C
3
B
3
C
4
B3 7
3 18.6
C
3
B
4
C
3
B4 6
4 24.8
C
2
B
5
C
3
B5 5
5 30.9
B
2
C
6
B
2
BC 6
4 24.8
C
2
B
2
C
2
B
2
C
2
CB 6
4 24.8
injected into the impregnated preform at a pressure of -80 kPa using a vacuum pump Airtech Ulvac G-100D, ULVAC
Kiko Incorporated, Japan. The panel was then dried inside an oven at 65
o
C for at least 2 h. In this work, we laminated 10 layers of fibers in every panel, constituting about 62 wt
of the hybrid composite. The thickness of panels manufac- tured through VARTM was approximately 2 mm. The details
of the combination of the fibers are shown in Table 1.
2.3 Tensile test and characterization
In the present study, tensile tests were performed to determine the stress-strain behavior of each composite
carbon-basalt fibersepoxy in accordance with ASTM D 638 [28]. Five dog-bone-type specimens were cut for each
composite panel using water-jet machining see Figure 2. The tensile tests were performed in a universal testing
machine Unitect-M, RB Research and Business, Korea at a constant crosshead speed of 2.0 mmmin at room tem-
perature. The strain was measured through an extensom- eter with a gage length of 50 mm Extensometer model
3542-0200-50-ST, Epsilon Tech. Corp, WY, USA. The failed surface characterization of each specimen was investi-
gated and analyzed using SEM. Microscopic analyses were
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performed aiming to recognize the failure mode of each hybrid composite.
3 Results and discussion
3.1 Tensile properties
Figure 3 illustrates the typical stress-strain curves obtained from the tensile test for each laminate, and
Table 2 gives the summary of the mechanical properties. Here, the basalt fabric layers were placed between carbon
fabric layers i.e., B1–B5. It can be directly noticed that the behaviors of each laminate all showed a linear trend.
The slope of the stress-strain curves demonstrated a proportional decrease with the increase in the number
of basalt fibers in the composite laminates. However, the tensile strain showed an increasing trend with the
increase in the number of basalt fabric layers. This signi- fies that at the highest number of basalt layers, i.e., B5, the
composite laminate showed the highest tensile strain. In
Figure 2 Schematic of dog-bone-type specimen for tensile test.
Figure 3 Stress-strain curves of CFRP, BFRP, and hybrid composites with different numbers of basalt fiber layers.
Table 2 Mechanical properties of CFRP, BFRP, and hybrid composites with different contents of basalt fiber into the
carbon fiberepoxy laminate.
Hybrid code
Tensile strength
σ
MPa Young’s modulus
E GPa Tensile
strain ε
CFRP 687
65 1.062
B1 630
60 1.07
B2 602
55 1.095
B3 558
50 1.1
B4 536
45 1.14
B5 502
40 1.2
BFRP 402
18 2.2
contrast, the tensile strength of the composites with the basalt fiber has values slightly lower than that of CFRP
but much higher than BFRP see Figure 3. In other words, the enhancement depending on the content of basalt fiber
has a significant impact on the ultimate strength, elastic modulus, and strain of the composite laminate. As a result
of basalt reinforcement in CFRP, the interply hybrid com- posites could take more strain before incurring failure
[1, 29].
Figure 4 shows photographic images of the failed samples after the tensile test. The laminate with only one
layer of basalt fiber in CFRP Figure 4A showed a brittle mode of failure. However, the damage modes of compos-
ite laminates B2, B3, B4, and B5 Figure 4B–D demon- strated many dispersed failure fibers. B4, with four plies
of basalt fiber, incurred flat damage on carbon layers after the tensile test and disperse fiber failure on the basalt
layer Figure 4D, which means that the interply hybrid composites can take more strain before failure under
tensile loading. Similar results were also reported by other research groups [30, 31] when they investigated the behav-
ior of FRP and hybrid FRP.
From Table 2, the results of the mechanical proper- ties depending on the basalt content show a linearly
decreasing tensile strength and Young’s modulus values of the hybrid composites with the increase in the number
of basalt layers. This signifies that the incorporation of basalt fiber significantly affected the tensile behavior of
hybrid composites. However, an increase of basalt fibers also raises the strain behavior of hybrid composite.
Here, we can make the approximate relations for the tensile strength and the Young’s modulus of the interply
hybrid composites as a function of the number of basalt fiber layers, x. It has been derived as follows:
σ
H
= -37x+687 MPa 1
E
H
= -5x+64 MPa 2
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3.2 Hybridization effect
