Fig.1 exhibits the XRD and XPS patterns of PC-LMS coating and SAPS-LMS coating. The PC-LMS coating was composed of Sic(hexagonal), MoSi2 (tetragonal) and LaB6 (cubic), Al2O3(hexagonal), as shown in Fig.1(a), which retained the phase structures of the precursor powders. It means that phase transition hardly occurs during the process of high-heat treatment under the protective atmosphere.Differently, for the SAPS-LMS coating(Fig.1(b)), the original phases of MoSiz(tetragonal), SiC (hexagonal), LaBo(cubic) and the new phases of MoO3(orthorhombic) and MosSig(tetragonal) were detected. Theformation of these new phases could be ascribed to the partial oxidation of molten droplets in air during the spraying process. XPS spectrum(Fig.1(c)) showed that the photoelectron peaks of Al2p(74.25 eV), Si2p(104.82 eV),B1s(189.48 eV), Mo3d (233.08eV),C1s(283.81eV), Mo3p(389.84 eV) and La3d(843.25 eV) Auger signals in PC-LMS coating were identified, which revealed that the PC-LMS coating consists of Al, Si,B, Mo,C and La elements. However, SAPS-LMS coatings are distinct that the O element(O1s,531.08 eV) can be observed except for the above elements(excluding Al element). The emergence of O element may be related to the oxidation of mixed powder during spraying process, which are consistent with the results of XRD analysis.
Fig. 1. XRD patterns (a, b) and XPS wide scan spectrum (c) of the LMS prepared by two different techniques: (a) PC-LMS coating; (b) SAPS-LMS coating.
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