Navigation
 

Hexoloy Mechanical Seal Face Introduction

Home : Product Applications : Mechanical Seal Faces

Hexoloy®SiC... Your Mechanical Seal Face Material Solution

Saint-Gobain Ceramics offers a family of Hexoloy sintered alpha silicon carbide grades, providing high performance seal face materials that have proven successful in such diverse applications as automotive water pumps, chemical processing, refining, mining, pulp and paper processing, mixers, and refrigeration.

No other commercially available seal material offers the performance package Hexoloy SiC provides.

The advantages of Hexoloy SiC include:
  • As the hardest commercially available seal face material, it provides wear resistant, long service life.
  • Its universal corrosion resistance offers a seal face material with unlimited application potential.
  • Low friction and high strength characteristics result in superior high PV performance.
  • It has high thermal conductivity for excellent thermal shock resistance.
  • Net shape manufacturing capabilities eliminate costly machining operations.
  • Hexoloy SP's unique spherical pore based lubrication delivers excellent hard face vs. hard face performance.
  • The material's low density (one-fifth of tungsten carbide) results in low power consumption in high speed applications.

Whether the application involves exposure to corrosive environments, abrasives, high temperatures and pressures, or high speeds, Hexoloy sintered alpha silicon carbide will outperform other hard face materials including fine-grained, reaction bonded SiC and tungsten carbide.


There's a Hexoloy® SiC Material for your application

Hexoloy SA Silicon Carbide
Hexoloy SA SiC is a pressureless, sintered form of alpha silicon carbide, with a density greater than 98 percent theoretical. It has a very fine grain structure (less than 10�m) for excellent wear resistance and contains no free silicon, which makes it highly chemically resistant in both oxidizing and reducing environments. The combination of fine grain structure and universal corrosion resistance results in a hard face material with excellent performance in a wide range of applications.
hexoloySA.gif
  • Hexoloy SA outperforms tungsten carbide, aluminum oxide and reaction bonded SiC in all chemical environments.
Hexoloy SP Silicon Carbide
Hexoloy SP SiC is a sintered alpha silicon carbide material designed specifically for optimum performance in sliding contact applications such as pump seal faces. This material improves upon the exceptional corrosion and erosion resisting properties of Hexoloy SA SiC through the addition of unique spherical pores. These discrete, evenly dispersed pores act as fluid or lubricant reservoirs helping to promote the retention of a fluid film at the interface of sliding component surfaces. (Reference Hexoloy SP SiC performance charts)
hexoloySP.gif
  • Hexoly SP outperforms hard face materials in the critical areas of friction and wear against a typical carbon mating face.
  • Hexoloy SP provides the optimal solution for severe applications requiring hard on hard seal face combinations (SP vs. SP).
Hexoloy SP SiC Performance







Corrosion Test Results in Liquids
Test Environment*
 
Corrosive Weight Loss (mg/cm2 yr)**
Conc. Reagent
Temp.
Hexoloy® SA/SP
Reaction
Bonded SiC
Tungsten Carbide
Aluminum Oxide
(Wt%)
(°C)
(No Free Si)
(12% Si)
(6% Co)
(99%)
98% H2SO4
100
1.8
55.0
>1000
65.0
50% NaOH
100
2.5
>1000
5.0
75.0
53% HF
25
<0.2
7.9
8.0
20.0
85% H3PO4
100
<0.2
8.8
55.0
>1000
70% HNO3
100
<0.2
.5
>1000
7.0
45% KOH
100
<0.2
>1000
3.0
60.0
25% HCl
70
<0.2
0.9
85.0
72.0
10% HF plus 57% HNO3
25
<0.2
>1000
>1000
16.0
*Test Time: 125 to 300 hours of submersive testing, continuously stirred.
**Corrosion Weight Loss Guide:
   >1000 mg/cm2 yr
  
Completely destroyed within days
   100 to 999 mg/cm2 yr
  
Not recommended for service greater than one month
   50 to 100 mg/cm2 yr
  
Not recommended for service greater than one year
   10 to 49 mg/cm2 yr
  
Caution recommended, based on the specific application
   0.3 to 9.9 mg/cm2 yr
  
Recommended for long term service
   <.2 mg/cm2 yr
  
Recommended for long term service: no corrosion, other than as a result of surface cleaning was evidenced

Noralide® NBD-200 Hot Pressed Silicon Nitride
Noralide® NBD-200 Hot Pressed Silicon Nitride (Si3N4) offers a combination of characteristics that make it an ideal material for mechanical seal face components as well as for other applications where maximum fracture toughness and flexural strength are required. Hot-pressed for maximum strength and density, Noralide� Si3N4 provides better fracture resistance than other ceramic materials. It can easily be machined in a variety of shapes and worked to close tolerances.


Unpolished NBD-200 at 100X
 
Etched NBD-200 at 1000X

Compare Hexoloy® SiC to Other Common Seal Face Materials








Testing shows that Hexoloy SiC outperforms other common seal face materials in properties such as hardness, thermal conductivity and specific strength.

Some examples of how Hexoloy SiC solves application requirements
Automotive Water Pumps � Because of greater resistance to both wear and thermal shock, Hexoloy SiC has replaced aluminum oxide as the material of choice for automotive water pump seal faces, one of the most challenging hard-on-hard applications. Over 20 million units are sold annually to meet the demands of U.S. and European automakers.

Chemical Processing - Hexoloy SiC provides a universal solution for many applications in the chemical processing industry where corrosion resistance and high temperature resistance are critical in such demanding environments.

Oil Refineries - Hexoloy SP is the ideal solution for oil refinery applications where limited lubrication situations occur. Hexoloy SP provides exceptional low friction properties while retaining univeral corrosion resistance.

Industrial Applications - Net shape moldable Hexoloy SiC offers a high performance, cost-effective seal face solution for high volume general purpose industrial pump seals.

Special Applications - Hexoloy SiC can be applied in critical seal face applications such as high speed compressors and nuclear reactor cooling water pumps.

Your Applications - Contact Saint-Gobain Ceramics engineers to assist you in the design of a seal face solution for your seal needs.

Hexoloy SiC the way you need it
Saint-Gobain Ceramics, Structural Ceramics, supplies both Hexoloy SA and Hexoloy SP as:
  • Finished components
  • Unfinished tubes and machined blanks
  • Pressed near net shape blanks
  • High volume pressed net shape components
  • Complex, highly machined parts
Your Source for Cost-Effective Hexoloy SiC...Worldwide
Saint-Gobain Ceramics offers vast resources to meet your needs for silicon carbide products. With representation in Asia by Norton KK (a Saint-Gobain company) and locations in Europe, Australia and South America, we can deliver your solution when you need it, where need you need it, in virtually every corner of the world.

   

Seals

seals1-r01.jpg
Automotive Water Pumps


Refineries


Chemical Processing Plants


Mixers


Nuclear Power Plants

seals1-r06.jpg
Pulp and Paper

seals1-r07.jpg
Marine Applications

seals1-r08.jpg
Refrigeration Compressors

Material Properties - Typical Values
Property
Units
Hexoloy SA SiC
Hexoloy SP SiC
Hexoloy Enhanced® SA
Noralide®
NBD-200 Si3N4
Composition*
-
SiC
SiC
SSiC
Si·N
Grain Size
µm
4-10
4-10
4-10
<2
Density
g/cm3
3.10
3.04
3.13
3.18
Hardness(Knoop 0.1kg load)
kg/mm2
2800
2800
2800
N/A
Hardness(Vickers 10kg load)
GPa
N/A
N/A
N/A
16
Flexural Strength
4pt @ RT**
MPa
x103 lb/in2
380
55
240
35
428
62
800
-
Compressive
Strength @ RT
MPa
x103 lb/in2
3900
560
N/A
3900
560
3500
-
Modulus of
Elasticity @RT
GPa
x106 lb/in2
410
59
400
58
410
59
320
-
Weibull Modulus
(2 parameters)
 
8
19
12
N/A
Poisson Ratio
 
0.14
0.14
0.14
N/A
Fracture Toughness @RT
Double Torsion & SENB
MPa x m1/2
x103 lb/in2 x in1/2
4.60
4.20
4.3
3.9
4.60
4.20
-
-
Fracture Toughness @ RT Indentation
MPa x m1/2
-
-
-
4.1
Coefficient of Thermal Expansion
RT to 700°C
x10-6 mm/mmK
x10-6 in/in °F
4.02
2.20
4.2
2.3
4.02
2.20
2.9***
-
Max. Service Temp. Air
°C
°F
1900
3450
1900
3450
1900
3450
N/A
Mean Specific Heat @ RT
J/gmK
0.67
0.59
0.67
N/A
Thermal Conductivity @ RT
W/mK
Btu/ft h°F
125.6
72.6
110
64
125.6
72.6
 
N/A
@ 100°C
W/mK
Btu/ft h°F
N/A
N/A
N/A
N/A
29
@ 200°C
W/mK
Btu/ft h°F
102.6
59.3
N/A
102.6
59.3
N/A
@ 400°C
W/mK
Btu/ft h°F
77.5
44.8
N/A
77.5
44.8
N/A
Permeability @ RT to 1000°C
Impervious to gases over 31 MPa
Electrical Resistivity @ RT****
@ 1000°C
ohm-cm
ohm-cm
102-108
0.01-0.2
N/A
102-108
0.01-0.2
>1012
Emissivity
 
0.9
0.9
0.9
N/A
Pore Volume Fraction
%
N/A
4.0-6.0
N/A
N/A
Pore Size
�m
N/A
50
N/A
N/A
*Composition code: Si = free silicon metal;
 C = free graphite; SiC = silicon carbide;
 N = nitrogen; Si3N4 = silicon nitride
      
***RT to 1000°C
****Dependent upon dopants in Hexoloy®SA
      SiC which will decrease electrical resistivity
**Test Bar Size: 3 x 4 x 45 mm
   (0.118" x 0.157" x 1.772")
 


We supply Hexoloy SiC:

  • Finished components
  • Unfinished tubes and machined blanks - See PDF
  • Pressed near net shape blanks
  • High volume pressed net shape components
  • Complex, highly machined parts