Callister - An introduction - 8th edition

16.9 Metal-Matrix Composites • 653
centimeters is
V c pL 4 1d o 2 d i 2 2
(16.24)
p1100 cm2
317.0 cm2 2 15.0 cm2 2 4
4
1885 cm 3 1114 in. 3 2
Table 16.7
Fiber and Matrix Volume Fractions
for Three Carbon-Fiber Types as
Required to Give a Composite
Modulus of 69.3 GPa
Fiber Type V f V m
Glass 0.954 0.046
Carbon 0.293 0.707
(standard modulus)
Carbon 0.237 0.763
(intermediate modulus)
Carbon 0.168 0.832
(high modulus)
Thus, fiber and matrix volumes result from products of this value and the V f and
V m values cited in Table 16.7. These volume values are presented in Table 16.8,
which are then converted into masses using densities (Table 16.6), and finally
into material costs, from the per unit mass cost (also given in Table 16.6).
As may be noted in Table 16.8, the material of choice (i.e., the least expensive)
is the standard-modulus carbon-fiber composite; the relatively low cost per
unit mass of this fiber material offsets its relatively low modulus of elasticity and
required high volume fraction.
Table 16.8
Fiber and Matrix Volumes, Masses, and Costs and Total Material
Cost for Three Carbon-Fiber Epoxy–Matrix Composites
Fiber Fiber Fiber Matrix Matrix Matrix Total
Volume Mass Cost Volume Mass Cost Cost
Fiber Type (cm 3 ) (kg) ($US) (cm 3 ) (kg) ($US) ($US)
Carbon 552 0.994 59.60 1333 1.520 9.10 68.70
(standard
modulus)
Carbon 447 0.805 76.50 1438 1.639 9.80 86.30
(intermediate
modulus)
Carbon 317 0.571 142.80 1568 1.788 10.70 153.50
(high
modulus)
16.9 METAL-MATRIX COMPOSITES
metal-matrix
composite
As the name implies, for metal-matrix composites (MMCs) the matrix is a ductile
metal. These materials may be used at higher service temperatures than their basemetal
counterparts; furthermore, the reinforcement may improve specific stiffness,