J.B. Davis et al. /Composites: Part A 30 (1999)483-488 100 -Nextel 440 1205 C ---- Nextel 440 1100 C f+=-se--aC 2 sh eta onazite Powder Filled 100 人(从 0-N ”只。、 2-theta Fig. 2. X-ray diffraction results. (a) Nextel 440 fibers after heat treatment for I hat 1 100 and 1200.C. Mullite peaks are identified. (b)Monazite- based coating after heat treatment for I h at 1100"C (F fabric peaks, M= monazite peaks, A= alumina peaks, S= SiC peaks) Ames Research Center for TPS evaluation. The tests were peaks and high background levels characteristic of amor- conducted for 600 s phous material. After heating to 1200.C, the pattern consisted primarily of narrow crystalline mullite peaks The monazite powders obtained from stoichiometric 3. Results solutions were in some instances mixed with powders of Al2O3 and Sic (which is commonly used as an additive to 3.1. Chemical compatibility and coating microstructure TPS coatings to increase their emittance). In all cases, the only peaks found in the X-ray diffraction patterns after firing X-ray diffraction studies of uncoated, heat-treated Nextel to 1200"C were those associated with the individual powder 440 fibers revealed a change in their structure at tempera- phases. No reactions between the coating constituents were tures between 1100 and 1200.C(Fig. 2). In the as-received observed state and after heat treatment at temperatures up to 1 100C, Coated fabrics were heat treated and X-rayed the X-ray diffraction pattern consisted of a few very broad conditions identical to those used for the uncoatedAmes Research Center for TPS evaluation. The tests were conducted for 600 s. 3. Results 3.1. Chemical compatibility and coating microstructure X-ray diffraction studies of uncoated, heat-treated Nextel 440 fibers revealed a change in their structure at tempera￾tures between 1100 and 12008C (Fig. 2). In the as-received state and after heat treatment at temperatures up to 11008C, the X-ray diffraction pattern consisted of a few very broad peaks and high background levels characteristic of amor￾phous material. After heating to 12008C, the pattern consisted primarily of narrow crystalline mullite peaks. The monazite powders obtained from stoichiometric solutions were in some instances mixed with powders of Al2O3 and SiC (which is commonly used as an additive to TPS coatings to increase their emittance). In all cases, the only peaks found in the X-ray diffraction patterns after firing to 12008C were those associated with the individual powder phases. No reactions between the coating constituents were observed. Coated fabrics were heat treated and X-rayed under conditions identical to those used for the uncoated fabric J.B. Davis et al. / Composites: Part A 30 (1999) 483–488 485 Fig. 2. X-ray diffraction results. (a) Nextel 440 fibers after heat treatment for 1 h at 1100 and 12008C. Mullite peaks are identified. (b) Monazite-based coatings after heat treatment for 1 h at 11008C (F ˆ fabric peaks, M ˆ monazite peaks, A ˆ alumina peaks, S ˆ SiC peaks)