Item

Unit

Steel

Si₃N₄

ZrO₂

Al₂O₃

Density

g/cm³

7.85

3.20-3.30

6.05

3.95

Thermal Expansion Coefficient

10^-6/k

10.0

3.2

10.5

9.1

Elastic Modulus

GPa

208

300-320

210

380

Possion Ratio

0.30

0.26

0.30

0.27

Hardness

(HV)

700

1500-1800

1200

1800

(HRC)

62

75-80

70

80

Bending Strength(800℃)

MPa

2400

200

300

220

Crushing Strength(800℃)

MPa

--

1400

2100

1500

Fracture Toughness

MPa.m^1/2

25.0

6.0-7.0

10.0

3.5

Thermal Conductivity(500℃)

W/mk

30-40

18

2

25

Specific Resistivity(600℃)

Ω.mm²/m

0.1-1

10¹⁸

10¹⁵

10⁸

Max Usage Temperature

℃

300

800

550

1850

Corrosion Resistance

Worse

Better

Better

Better

Fatigue Stress Recycles(50% Fail)

Times

10⁷

10⁷~10⁹

10⁵

-

Dimension Stablity with Temperature

Large

Little

-

-

Centrifugal Force

Large

Little

Large

Medium

Non-Lubrication Friction

Large

Little

Little

Little

Magnetism

Exist

Naught

Naught

Naught

Failure Mode under Rolling Contract

Flake

Flake

Smash

Smash