UltraHard Materials LLC
Comparing UHM’s CeTZP with Silicon Nitride
Silicon Nitride is probably the most common engineering ceramic that is currently being used in applications where a higher performance material is required despite its low fracture toughness.
Table 8
Table 8 lists the mechanical properties of UHM’s CeTZP compared to Silicon Nitride (from references 4,5,7,15).
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Mechanical Properties
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UHM's CeTZP
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Silicon Nitride
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Vickers Hardness (GPa)
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9.1 - 13.6+
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17 - 19+
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Fracture Toughness (MPa.m1/2)
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10 - 15.3
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4.0 - 5.4
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Tensile Strength (MPa)
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360 - 420#
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400 - 580#
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Bend Strength (MPa)
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1080 - 1260
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190 - 980
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Compression Strength (MPa)
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1045 - 1459
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550 - 2000
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Young’s Modulus (GPa)
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190 - 200
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280 - 310
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Density (g/cm3)
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6.1 - 6.2
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3.2 - 3.5
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#estimated from bend strength
+ higher values can be obtained when lower indenter loads are used during Vickers hardness measurements (reference 10).
[All our mechanical tests were carried out on UHM's CeTZP billets. A LECO test machine for our indentation macrohardness tests utilized 30 kg loads; K1c values were calculated from crack lengths derived from these indentation tests using the equation of Anstis el alia (reference 10)]
UHM’s CeTZP engineering ceramic has some clear mechanical property advantages over Silicon Nitride and they are:
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The fracture toughness of UHM’s CeTZP is about three times (or 300%) higher than Silicon Nitride. This means that UHM’s CeTZP is less likely to fracture under higher load-bearing conditions than Silicon Nitride
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The Bend Strength of UHM’s CeTZP is higher than that of Silicon Nitride
Table 9
Table 9 lists the thermal properties of CeTZP compared to Silicon Nitride (from references 4,5,7,15)
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Thermal Properties
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UHM’s CeTZP
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Silicon Nitride
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Thermal Expansion Coefficient (10-6/K)
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10 - 12
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2.6 - 3.3
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Thermal Conductivity (W/m.K)
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1.9
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15 - 43
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CeTZP engineering ceramic has some thermal property advantages over Silicon Nitride and they are:
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The thermal expansion coefficient of CeTZP is comparable to that of cast iron (Silicon Nitride has a much lower thermal expansion coefficient which would make Silicon Nitride a mismatch with cast iron)
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CeTZP has a lower thermal conductivity than Silicon Nitride. Thus, CeTZP is a better candidate material than Silicon Nitride for heat engines.