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 Thermic Edge LTD.
30 Brunel Road,
St. Leonards on Sea,
East Sussex
TN38 9RT
England
 
Telephone:
+44(0)1424 850811
 
E-mail:
sales@thermic-edge.com
 
 
 
 
MacorShapalBoron NitridePyrolytic BNOxides/AluminaNitridesCarbides

Oxides - Alumina Oxide, Zirconia/Zirconium Oxide

 

Alumina, Zirconia
Alumina and zirconia are hard wearing materials used for many applications. Once fired and sintered, they can only be machined using diamond-grinding methods.

Alumina's combination of hardness, high temperature operation and good electrical insulation makes it useful for a wide range of applications. Alumina is the most commonly used type of ceramic and is available in purities up to 99.9%.

Zirconia is similar to alumina in many of its properties but offers significant improvement in fracture toughness. It is particularly useful in applications where the mechanical strength of alumina is not sufficient.

Typical applications: electrical insulators; seal faces; valve seats.

 

Oxides Physical Properties

 

name Alumina
96%
Substitute
High-Purity
crystalised
Alumina
High-Purity
Alumina
Quartz Sapphire BeO Zirconia
Yttizia
Stabalised
Zirconia
Mgo
Stabalised
Steel(mild)
colour white off-white off-white clear clear white white cream grey
density 3.8g/cm 3.8g/cm 3.5g/cm 2.2g/cm 4g/cm 2.9g/cm 8g/cm 5.6g/cm 7.85kg dm
porosity 0% 0% 0% 0% 0%    0% 0% 0%
poissons ratio

 

                  0.3 0.31 0.27-0.30
thermal
conductivity

 

24
Wm/K
30
Wm/K
28-28
Wm/K
1.48
Wm/K
35-40
Wm/K
260
Wm/C
2
Wm/K
2.5
Wm/K
50 Wm/C
coeffcient
of expansion

 

               8 x
10-6/K
   10 x
10-6/C
11x10/C
dielectric
strength

 

10
KV/mm
17
KV/mm
10
25KV/mm
25
40KV/mm
15
50KV/mm
10
KV/mm
        
dielectric
constant

 

9.8 9.9 9-10 3.8 7.5-
11.5
7
1MHZ
        
dielectric
loss tangent

 

               0.0003
1MHZ
        
flexual strength

 

               200
MPa
800-
1400
MPa
545
MPa
  
hardness 1500
Vickers
9
Mohs
Scale
1650
Vickers
1000
Vickers
1700
Vickers
1200
Vickers
1350
Vickers
910
Vickers
  
volume
resistancy

 

>1013
ohm/cm
>1014
ohm/cm
1014
ohm/cm
1018
ohm/cm
1014
ohm/cm
>1014
ohm/cm
>109
ohm/cm
>1010
ohm/cm
  
max. use temp

 

1600C 1900C 1650C 1100-1400C 2000C 1700C 1000C 1000C   
thermal
expansivity

 

   8.5x
10-16
7.5-
8.2
10-6
54
10-6
5.8
10-6
   10x10C    11x10/C
specific heat

 

800
J/KgK
900
J/KgK
880
J/KgK
700
J/KgK
750
J/KgK
1000-
1320
J/KgK
400
J/KgK
400
J/KgK
450J/kgK
compressive
strength

 

   3500
MPa
2000-
2250
GPh
1100 2100 1750
MPa
2000
MPa
1700
MPa
  

 

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