JMCUSA Ceramics

JMC (USA), Inc.

Silicon Nitride Ceramics

Grades and Specifications

JMC's Ceramics Product Line Includes:
Thermocouple Protection Tubes
Heater Protection Tubes
Metal Degassing Equipment
Burner Flame Diffusers
Vega's Robe (release agent)
Miscellaneous shapes including hooks, nozzles and ladles

Silicon nitride ceramics exhibit superior corrosion resistance
for molten metals including aluminum, zinc and brass.

Grade	Description	Characteristics
NSSN	Pressureless sintered	Well balanced and versatile material -- our standard.
BNSN	Boron nitride composite	High resistance to thermal shock and elevated temperature, excellent machineability.
WRSN	Whisker reinforced	Superior thermal shock resistance and mechanical strength.
RBSN	Reaction bonded	Minimal deterioration at elevated temperatures, an economical alternative.

Material Properties

Grade	NSSN	BNSN	WRSN	RBSN
Structure	Dense	Dense-Porous	Dense	Porous
Composition (%)	-	BN 5, 10, 20%	SiC(w) 20%	BN 10, 20% or SiC 50%
Bulk density (g/cm³)	3.1	2.1-2.5	3.2	2.1-2.3
Apparent porosity (%)	<0.1	7-24	<0.1	24-28
Flexural strength (MPa)	690	160-620	940	40-100
Thermal shock resistance ( ^oC)	700	>1000-850	>1000	700-450
Fracture toughness (MPa^.m^1/2)	4.8	-	7.5	-
Thermal conductivity (W/m^.k)	18.4	-	29.6	4-12
Applications	Thermocouple protection & Heater protection tubes, precision mechanical parts	Nozzles, Stoppers etc.	Boiler parts (burner diffuser, air nozzle), plasma related parts	Nozzles,Stoppers etc.