Ultralight Silicon Nitride Ceramic Foams from Foams Stabilized by Partially Hydrophobic Particles

Ultralight Si 3 N 4 ceramic foams have been successfully prepared through particle‐stabilized foams method, which is based on the adsorption of in situ hydrophobized Si 3 N 4 particles to the liquid/air interface of the foams. Here, we firstly used a long‐chain surfactant cetyltrimethylammonium chloride to render the Si 3 N 4 particles partially hydrophobic. By tailoring the surfactant concentration and pH values of the suspensions, the wet foams were stabilized to avoid coarsening and coalescence. SEM results show that the Si 3 N 4 ceramic foams possess single strut walls with elongated β‐Si 3 N 4 grains interlocking with each other, and their pores are uniform with an average pore size of 95 μm. The obtained ceramic foams maintain compressive strength of 1.34 ± 0.13 MP a with porosity of 92.0%, when the suspension contains 3 mmol/L surfactant at the pH of 11.0.