S. Wannaparhun et al /Applied Surface Science 185(2002)183-196 a 115 74N BE.(ev) Fig. 11. XPS Si(2p)spectrum:(a)the calculated spectrum of the composite(F: fiber and M: matrix); (b)the as-received composite is more than that of the matrix(0.03). Hence, the 3.4. The composite position of Si(2p)in the fiber(101.8 ev) is presented at a higher BE compared to the matrix(101.5 eV It is necessary to understand the geometry of the as- This study is similar to studies of various zeolite received CMC for determining an analyzed surface systems studied by Barr [50,52]. Any change in the using XPS. Herein, the geometry of the CMC can be Al ratio in the complex zeolitic oxide lattice will illustrated using a Cartesian coordinate(Fig. 13a) produce a corresponding change in the core level According to the manufacturing of this particular binding energies results in significant chemical shifts CMC, the woven fiber fabrics are laid upon X-Y plane, in the XPS corelines of interest. The change in the Be infiltrated with alumina, and then stacked up in position of the Si(2p) peak is predominantly attrib- Z-direction to form the CMC of a desired thickness uted to changes in the sial ratio The SEM images indicate two possible surfaces to be analyzed: (i)top surface(Fig. 13b)and(ii)cross- 3.3.3. XPS O(ls) sectional surface(Fig. 13c). It is important to select the Both individual and deconvoluted spectra are listed top surface for the XPS analysis in order to maximize in Fig. 12a. The peaks located at 530.8ev(11.7% the probability of detecting the interface between the area)and 531. 1 ev(88.3%o area) indicate a predomi- fiber and the matrix phase. It is noteworthy that the nant peak of aluminosilicate(531.6 eV) and the minor XPS spectra obtained from the top surface of the Cmo peak is assigned to Al2O3(530.9 eV)(51]. The decon- will depend on the distribution of the matrix on the voluted XPS O(Is) spectra were consistent with the surface. If the fiber fabric at the topmost layer is fully Al(2p) spectrum, where aluminosilicate was also covered with the matrix of the thickness more than the found to be the major component in the Nextel-720 depth resolution of the XPs(depends on the incident angle of the X-ray ), the signal will only come from theis more than that of the matrix (0.03). Hence, the position of Si(2p3 ) in the fiber (101.8 eV) is presented at a higher BE compared to the matrix (101.5 eV). This study is similar to studies of various zeolite systems studied by Barr [50,52]. Any change in the Si/Al ratio in the complex zeolitic oxide lattice will produce a corresponding change in the core level binding energies results in significant chemical shifts in the XPS corelines of interest. The change in the BE position of the Si(2p3 ) peak is predominantly attrib￾uted to changes in the Si/Al ratio. 3.3.3. XPS O(1s) Both individual and deconvoluted spectra are listed in Fig. 12a. The peaks located at 530.8 eV (11.7% area) and 531.1 eV (88.3% area) indicate a predomi￾nant peak of aluminosilicate (531.6 eV) and the minor peak is assigned to Al2O3 (530.9 eV) [51]. The decon￾voluted XPS O(1s) spectra were consistent with the Al(2p) spectrum, where aluminosilicate was also found to be the major component in the Nextel-720 fiber. 3.4. The composite It is necessary to understand the geometry of the as￾received CMC for determining an analyzed surface using XPS. Herein, the geometry of the CMC can be illustrated using a Cartesian coordinate (Fig. 13a). According to the manufacturing of this particular CMC, the woven fiber fabrics are laid upon X–Y plane, infiltrated with alumina, and then stacked up in Z-direction to form the CMC of a desired thickness. The SEM images indicate two possible surfaces to be analyzed: (i) top surface (Fig. 13b) and (ii) cross￾sectional surface (Fig. 13c). It is important to select the top surface for the XPS analysis in order to maximize the probability of detecting the interface between the fiber and the matrix phase. It is noteworthy that the XPS spectra obtained from the top surface of the CMC will depend on the distribution of the matrix on the surface. If the fiber fabric at the topmost layer is fully covered with the matrix of the thickness more than the depth resolution of the XPS (depends on the incident angle of the X-ray), the signal will only come from the Fig. 11. XPS Si(2p3 ) spectrum: (a) the calculated spectrum of the composite (F: fiber and M: matrix); (b) the as-received composite. S. Wannaparhun et al. / Applied Surface Science 185 (2002) 183–196 191