Page 239 - Engineered Interfaces in Fiber Reinforced Composites

Chapter 5. Surfucr trautrnents of jihers und <!kcis on conipositc, properties 22 1

PYROCAQRON

~~

Fig. 5.34. Scanning electron microphotograph of a pyrocarbon coated Nicalon Sic fiber. After Chawla
(1993), Fig. 9.15, p. 320. Reproduced by permission of Chapman & Hall.

TiO?) result in substantial improvement in strength and toughness of the
composites. The BN coating reduces the interface bond strength between the Sic
reaction layer and the matrix. A duplex coating of SiC/BN applied to the Nicalon

250

200

100

50 i
,O 10 prn
+Uncoated . I
0 1 , I I I I I
0.1 0.2 0.3 0.4 0-5 0.6 0.7
Displacement (rnrnl
Fig. 5.35. Load- displacement records of Nicalon Sic fiber Sic matrix composites with varying
thicknesses of carbon coating. After Lowden (1991).