Hexoloy® SiC and Noralide Si3N4 Seals

Solutions for Mechanical Seals

Ground seal faces are available in Hexoloy® SA silicon carbide and Noralide® silicon nitride materials.

Both of these materials are fine-grained and produced to near theoretical density, ensuring excellent wear resistance required for seal face products.

Both materials possess outstanding resistance to corrosion from chemicals with a wide range of pH values. Seal faces are produced to custom drawings with high quality surface finishes.

Features and Benefits

Benefits
  • Exceptional hardness
  • Chemically inert to a broad range of chemicals
Applications
  • Seal faces for mechanical seals used in industrial pumps
Hexoloy® SA
Physical Properties Units

SA

Composition (phases)   SiC
Density g/cm3 3.10
Grain Size Qm 4-10
Hardness (Knoop)** kg/mm2 2800
Flexural Strength
4pt. @ RT***
MPa
x10lb/in2
380
55
Flexural Strength
3pt. @ RT***
MPa
x10lb/in2
550
80
Compressive Strength @ RT MPa
x103 lb/in
3900
560
Modulus of Elasticity @ RT GPa
x106 lb/in
430
62
Weibull Modulus (2 parameters)   10
Poisson Ratio   0.14
Fracture Toughness @ RT
Double Torsion & SENB
MPa x m½
103lb/in2 x in½
4.60
4.20
Coefficient of Thermal Expansion
RT to 700°C
x10-6mm/mm°K
x10-6in/in°F
4.02
2.20
Max. Service Temp (air) °C
°F
1900
3450
Mean Specific Heat @ RT J/gm°K 0.67
Thermal Conductivity @ RT W/m°K
Btu/ft h°F
125.6
72.6
@ 200°C W/m°K
Btu/ft h°F
102.6
59.3
@ 400°C W/m°K
Btu/ft h°F
77.5
44.8
Permeability RT to 1000°C   All impervious to gases over 31 MPa

Electrical Resistivity @ RT***
                                 @ 1,000°C

ohm-cm 102-108
0.01-0.2
Emissivity   0.9

* Composition code: Si = free silicon metal; C = free graphite; SiC = silicon carbide
* Knoop 100-gm load
*** Test Bar Size: 3 x 4 x 45 mm (0.118" x 0.157" x 1.772")
*** Dependent upon dopants in Hexoloy® SA SiC which will decrease electrical resistivity

Material Properties Noralide®
Physical Properties Units Value
Composition*   Si • N
Grain Size µm < 2
Density g/cm3 3.18
Hardness (Vickers)** GPa  16
Flexural Strength 4 pt @ RT***  MPa  800
Compressive Strength @ RT MPa  3500
Modulus of Elasticity @ RT  GPa  320

Fracture Toughness @ RT

Indentation

MPA x m1/2  4.2
Color   gray

Coefficient of Thermal Expansion

RT to 1,000°C

x10-6 mm/mmK  2.9
Thermal Conductivity @ 100 °C  W/mK  29
Electrical Resistivity @ RT***  ohm-cm > 1012
Purity   %
Si3N4    95
Al    0.35
C   0.50
Ca    0.01
Fe   0.02
Mg   0.60
O   2.5
Other   trace

* Composition code: Si = Free silicon metal, N = Nitrogen, Si3N4 = Silicon Nitride
** Vickers 10 kg load
*** TestBar Size: 3 x 4 x 45 mm (0.118" x 0.157" x 1.772")