Synthesis under NH3 and thermal behaviour of SiCNAlO polymer-derived nanopowders

Influence of H2/NH3 mixtures on the composition of SiCNYO and SiCNAl(O) nanopowders

“…The evolution of these elements with various amounts of NH 3 without H 2 was discussed previously. 5 With 10% H 2 introduced into the atmosphere with 5% and 25% NH 3 , similar evolutions were noted (decrease in C content and increase in N content). As well, O, Si and Al contents changed with the composition of the reactive atmosphere.…”

“…5,15 Powders were compacted at room temperature, and the obtained pellets were embedded in the rest of the powder in a glassy C crucible to prevent compositional changes during the annealing treatment. After the sample was introduced into the graphite chamber furnace, the temperature was increased to 1550 • C (with a 2-h holding time) at an average heating rate of 10 • C min −1 .…”

“…sis atmosphere. 5 For the experimental conditions studied, NH 3 introduced during the thermal pyrolysis is insufficient to avoid the formation of free C, whatever the NH 3 amount introduced into the pyrolysis atmosphere. However, for high contents of NH 3 , Si atoms seem to be saturated by an environment of N atoms, and the C/N ratio decreases.…”

“…The powders, containing a high content of free C, show a very low structural organization characterized by groups such as Si-C-N-Si and are thermally unstable. 5 Furthermore, the presence of free C in the Si 3 N 4 /SiC powders has a deleterious effect on the sintering behaviour.…”

Two synthesis routes of organometallic precursors for the elaboration of SiCNYO pre‐alloyed nanopowders

“…[15,20] Briefly, frequency and power alimentations of the aerosol generator device (RBI, Meylan, France) were adjusted respectively around 800 kHz and 100 W to obtain an aerosol with a suitable yield. Precursors, which were directly introduced as liquid precursor in the aerosol-generating chamber under argon, were nebulized and carried to the pyrolysis furnace with a 3 L/min argon flow rate.…”