Carbonitriding synthesis of β-SiAlON nanopowder from kaolinite–polyacrylamide precursor

Ceramic systems of Si–Al–O–N attract great technological interest because of their superior thermomechanical properties at high temperature.A precursor from acrylamide (AM) and kaolinite was prepared by free-radical aqueous polymerization, using N,N0-methylenebisacrylamide (MBA) as a cross-linker, ammonium persulfate (APS) as an initiator and tetramethylenediamine (TMD) as a catalyst.SiAlON nanopowder was synthesized from kaolinite–polyacrylamide (PAM) precursor by carbothermal reduction and nitridation processing (CRN) at different temperatures. XRD, XRF, FTIR, RAMAN, STA, SEM, and LLS were used to characterize the phases, structures, and morphologies of the products.As a result, Si6 − zAlzOzN8 − z, with a z-value of about 3 is the main phase from the CRN process of kaolinite–PAM precursor which is well matched with the ratio of Si/Al in the precursor mixture. The yield of the synthesized SiAlON nanopowder in the product is about 85 wt.% and the rest is SiC and Si3N4 as impurities.

Research highlights
► Polyacrylamide Gel-net was employed to control the size of powders in nanoscale.
► CRN process was used as an effective method in SiAlON synthesis.
► The yield of β-SiAlON in the final product was about 85 wt.%.
► The z-value of as-synthesized β-SiAlON, determined by various techniques, was about 3.