Design of Porosity Level for Porous Si₃N₄ Ceramics Manufactured by Nitriding and Post-Sintering of Si Powder Compact

Abstract

Prediction of porosity level for the Si3N4 filter substrate manufactured by reaction bonding of Si compact and subsequent post-sintering was attempted and its validity was verified by comparison between calculation and measurement. Both are well matched in the specimens of asnitrided and low temperature post-sintering, while few percents higher measurement in high temperature post-sintered specimens resulted from weight loss during the process.

Permeability Enhancement in Porous-Sintered Reaction-Bonded Silicon Nitrides

“…Authors have reported that the pore structure is determined by the Si to the pore former size ratio. 28 Thus, increased packing density by means of adding small Si 3 N 4 particles between larger Si particles should create a stable strut structure after the decomposition of the pore former. In this study, PMMA of j 5 8 and 50 mm were used to investigate the effect of pore size on permeability.…”

The Characterization of Porous Sintered Reaction-Bonded Silicon Nitride Ceramics Fabricated by Si-Additive Mixture Granules

“…With preferred material properties such as complex pore channel paths and large specific surface area aided by their rod‐like grain morphology, silicon nitride (Si 3 N 4 ) ceramics make excellent candidates for filtering media 1–3 . However, the diameter (ϕ) of the pore channels in porous sintered reaction‐bonded silicon nitride ceramics (SRBSNs) is usually restricted to ∼1 μm for the following reasons: (1) the nitriding mechanism involves both gas and solid phases, and (2) grain growth is limited to 1–2 μm in the porous body by the liquid phase sintering vehicle 3–5 . As narrow pore channels produce a large pressure drop across current SRBSN filters, the widening of their pore channels to the size of those in commercial filters (ϕ≥10 μm) is strongly desired.…”