Transcript CHAPTER OBJECTIVES - USF College of Engineering

Metal Matrix Composites

What are metal-matrix composites?
Metal matrix composites have a metal
matrix.
Examples include silicon carbide fibers in
aluminum, graphite fibers in aluminum.
Advantages of MMCs
Higher specific strength and modulus over
metals.
 Lower coefficients of thermal expansion
than metals by reinforcing with graphite.
 Maintenance of high strength properties at
high temperatures.

Degrading properties in MMCs

2a


Are there any properties
which degrade when
metals are reinforced
with fibers?
Yes, they may have
reduced ductility and
fracture toughness.
Typical mechanical properties of
metal matrix composites
Property
Units
Specific Gravity
SiC/
Aluminum
2.6
Graphite/
Aluminum
2.2
Steel
Aluminum
7.8
2.6
Young’s modulus
Msi
17
18
30
10
Ultimate Tensile Strength
Ksi
175
65
94
34
6.9
10
6.5
12.8
Coefficient of Thermal Expansion in/in/F
Boron Fiber
Step 0: Cutting the shape
MINUM FOIL
Step 1: Apply Aluminum File
Step 3: Lay Up Desired Plies
Step 4:Vacuum the specimen
TEP 4:
TO VACUUM
VACUUME
VACUUM
ENCAPSULATE
Step5: Heat to Fabrication
Temperature
: HEAT TO FABRICATION TEMPERATURE
HEAT
HEAT
Step 6: Apply Pressure and Hold
for Consolidation Cycle
PPLY PRESSURE AND HOLD FOR CONSOLIDATION CYCLE
OL, REMOVE AND CLEAN PART
Step 7: Cool, Remove and Clean
Part
Foil
Fiber Mat
Foil
(a)
Stack
Consolidate
(c)
Schematic of
Diffusion
Bonding
(b)
(d)
Heat and Pressure
Clean and
Trim + NDE
(e)
Secondary Fabrication
(f)
Silicon Carbide/ Aluminum
Composite
Application of MMCs
Application of MMCs
Application of MMCs