Page 250 - 04. Subyek Engineering Materials - Manufacturing, Engineering and Technology SI 6th Edition - Serope Kalpakjian, Stephen Schmid (2009)

Section 9.6 Ceramic matrix Composites 22

TABLE 9.4

Summary of Fiber and Material Properties for an
Automotive Brake Caliper
Aluminum-reinforced
Property Alumina fiber composite material
Tensile strength 3100 MPa 1.5 GPa
Elastic modulus 380 GPa 270 GPa
Density 3.9 g/cm3 3.48 g/cm3

FIGURE 9.I| Aluminum-matrix composite brake caliper using
nanocrystalline alumina fiber reinforcement. Source: Courtesy of
3M Speciality Materials Division.

packaging-constrained environment. The new brake savings of 50% and brings added benefits of easy
caliper is shown in Fig. 9.11. It produces a weight recyclability and corrosion resistance

9.6 Ceramic-matrix Composites

Ceramic-matrix composites (CMC) are important because of their resistance to high
temperatures and corrosive environments. As described in Section 8.3, ceramics are
strong and stiff, they resist high temperatures, but they generally lack toughness.
Matrix materials that retain their strength up to 1700°C are silicon carbide, silicon
nitride, aluminum oxide, and mullite (a compound of aluminum, silicon, and oxy-
gen). Carbon/carbon-matrix composites retain much of their strength (up to
2500°C), although they lack oxidation resistance at high temperatures. Fiber mate-
rials are usually carbon and aluminum oxide. Applications of CMC include jet and
automotive engine components, deep-sea mining equipment, pressure vessels, struc-
tural components, cutting tools, and dies for the extrusion and drawing of metals.