Polymer–Ceramic Conversion of Liquid Polyaluminasilazanes for SiAlCN Ceramics

Abstract

Commercially available polyureamethylvinylsilazane (Ceraset, Kion Corporation, Huntington Valley, PA) and aluminum isopropoxide (Al(OCH(CH 3 ) 2 ) 3 ) (AIs, Alfa Aesar, Ward Hill, MA) were used as starting materials. Ceraset, as received, is a pale yellow liquid, and AIs is a white powder. Both materials were used as received without further purification. Figure 1 shows the chemical structure of Ceraset cited by the supplier 24-27 and confirmed by previous study. 28 The polyaluminasilazanes were prepared using the following procedure. First, AIs powders were dissolved in liquid Ceraset at room temperature while stirring magnetically. A small amount 2415 J ournal

Oxidation of Polymer‐Derived SiAlCN Ceramics

“…Figure 4 shows 29 Si spectra of the SiCN and SiAlCN oxidized at different conditions. The signals between 0 and −75 ppm result from the un‐oxidized substrates 26 . The spectra suggest that at 900°C, the oxide scale is thin and a significant amount of SiCN and SiAlCN substrates remain un‐oxidized after 50 h annealing while at 1200°C, most of the substrates were oxidized.…”

“…For comparison, fully dense SiCN discs were also prepared via the same procedure by using pure Ceraset as precursor. The chemical compositions of the SiCN and SiAlCN ceramics are listed in Table I 26 . The samples also contain ∼3 wt% oxygen.…”

Synthesis of cross‐linked polymer microspheres and pyrolysis conversion to polymer‐derived ceramics

“…The bands attributed to Si‐NH‐Si groups are the N–H stretching at 3380 cm −1 and the Si‐N‐Si vibration at 1165 cm −1 . The broad peaks from 700 cm −1 to 1100 cm −1 result from the mixture of two bonds: Si‐C and Si‐N . No new peaks are observed in the FT‐IR spectrum recorded for the polymer microspheres.…”

Pyrolytic conversion studies of blended polycarbosilane and polyaluminasilazane

“…The advantage of this approach is the preparation of near-net shape products [4,5] with a high purity, or the preparation of homogeneous multinary materials. Many ceramics have been fabricated by a polymerceramic conversion approach, for example SiC [6,7], SiCN [8][9][10], SiCO [11,12], SiAlCO [13,14], SiAlCN [15][16][17][18][19][20], SiBCN [21][22][23][24][25], SiTiCN [26], SiFeCN [27,28], SiYCN [29] and SiBCNAl [30]. Among these materials, polycarbosilane-derived amorphous SiC can be converted into nanocrystalline SiC at 1200°C under a protective atmosphere [7,31].…”