Table 1.

The classification of major processing strategies and corresponding compositions of porous ceramics produced from polysiloxane precursors.

Processing strategy	Composition	Remarks	References
I. Replica
	SiC	Open cells	[57–61, 63]
		Cell size: >150 μm
		Porosity range: 85–96%
	SiC–Si3N4		[57, 59, 60]
	SiC–TiC		[57]
	SiOC/C		[54]
II. Sacrificial template
	SiC	Open cells	[68, 72]
		Cell size: 10–100 μm
	SiOC	Open or closed cells	[69, 70]
		Cell density: >104 cells cm-3
		Porosity range: 21–80%
Expandable or PMMA templates	SiOC	Open, closed or partially interconnected cells	[67, 73–76]
		Cell size: 0.5–80 μm
		Cell density: >109 cells cm-3
		Porosity range: 56–88%
	SiC		[17, 77]
Expanded (hollow) templates	SiOC	Closed cells	[66]
		Cell size: <30 μm
		Cell density: >109 cells cm-3
		Porosity range: 70–87%
III. Direct foaming
Foaming by chemical agent	SiOC	Open, closed or interconnected cells	[6, 78, 81–85, 87, 139]
		Cell size: 80–800 μm
		Porosity range: 75–90%
	SiOC + SiC	Open cells	[82]
		Cell size: 100–700 μm
Foaming using CO2
Batch process	SiOC	Closed cells	[79, 90, 92, 96]
		Cell size: 2–50 μm
		Cell density: 107–1012 cells cm-3
		Porosity: 45%
	SiC		[90, 91]
Extrusion process	SiOC	Open or closed cells	[93, 94]
		Cell density: >107 cells cm-3
		Porosity range: 27–90%
IV. Reaction technique
	SiC	Open cells	[18, 97–102, 104–106]
		Cell size: 10–45 μm
		Cell density: >109 cells cm-3
		Porosity range: 32–94%
	Mullite	Partially interconnected open cells	[107–109 ]
		Cell size: <20 μm
		Cell density: >109 cells cm-3
		Porosity range: 32–85%
	Cordierite	Interconnected open cells	[110, 111]
		Cell size: 13 um
		Cell density: 109 cells cm-3
		Porosity range: 11–75%