Fracture toughness

Advanced ceramics offer exceptional mechanical properties compared to metals and plastics. Compressive strength is very high for all groups of advanced ceramics, but other properties, such as hardness, resistance to wear, shock resistance and flexural strength, vary from one type of ceramic to the next.

Description

Fracture toughness refers to the material's ability to withstand cracking caused by a shock wave crossing it. Ceramics with low elasticity (high Young’s Modulus), compared to metals, for example, do not offer high resistance to mechanical shocks. There is, however, a type of ceramic preferred for applications where the user requires flexural strength in addition to other mechanical properties: zirconium oxide (or zirconia), and, in particular, Y-TZP zirconia (yttria-stabilised zirconia) or ATZ. To a lesser extent, silicon nitride, alumina-toughened zirconia or certain alumina may also be used.

Application markets

These materials are used in a wide variety of business sectors: engineering (equipment manufacturers, special machines, processing equipment), defence and medical.

Comparative table of properties

Comparative table of mechanical properties
Values at ambient temperature – 20°c

Density

(g/cm3)

Resistance to compression

(MPa)

Resistance to bending

(MPa)

Young's modulus

(GPa)

Hardness

(Vickers -GPa)

Fracture toughness

K(Ic)
Alumina (94 to 99.8 % ) 3.6 to 3.9 1700 to 2500 250 to 350 350-370 12 to 18 4 to 5
Alumina-zirconia composites 4.0 2000 450 350 14 5 to 6
Zirconia MgO 5.5 >1700 550 to 700 170 to 200 11 to 12 6 to 8.5
Zirconia Y-TZP 6.0 2000 to 2500 900 to 1250 200 to 220 12 to 16 10 to 13
Aluminium nitride 3.3 2000 >300 310 - 3
Silicon nitride 3.2 2500 to 3000 650 to 900 300 to 315 15 to 16 7.5 to 8
Silicon carbide 3.1 2500 to 3900 400 to 550 410 24.5 to 28 4 to 4.6
Boron carbide 2.5 >1500 425 440 28 3 to 4

Acceptable: +  ;  Good: ++  ;  Very good: +++.

These values are for information only and do not constitute a contractual obligation.

Raw material
Finished product

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