1. Silicon Carbide for Secondary Collimators
R. Blanchon
5/20/2009

2. Specification Candidate: Silicon Carbide (SiC)
Ceramic absorber with metallic support
Dimensions: Tiles of 40 mm * 20 mm * 10 mm
Required properties:
Electrical resistivity: 1 to 100 Ω.m
Low CTE
High thermal conductivity and specific heat
High density
Candidate: Silicon Carbide (SiC)

3. Theorical electrical resistivity
Potential suppliers
ESK
(Ekasic T)
Saint-Gobain
Keramo
Boostec
CoorsTek
(Pure SiC LR)
Microcertec
Rohm & Haas
Production mode
Sintering
CVD
Theorical electrical resistivity
(Ω.cm) 1
No information
107
< 0.1 Or
> 106
< 10
> 1000
Contact
Tests
Waiting for samples

4. Potential suppliers
[J/kg]
[W/m]

5. Electrical ResistivityF Ω
First measurements on ESK samples
Without surface preparation
→ ρelec = 43 Ω.cm
With surface preparation
→ ρelec = 5380 Ω.cm
Graphitization of SiC
ESK
Keramo
Boostec
Longueur (cm)
4.99
5.00
2.50
Largeur (cm)
2.46
Hauteur (cm)
0.80
0.40
0.50
Resistivite 1 (Ω.cm) 43 / 19
Resistivite 2 (Ω.cm)
5380
447
179

6. Brazing tests (Ultrasounds)
40*24*8 mm3
8*24*8 mm3
Ag-Cu-Ti (780 °C)
Crack in SiC
Propagation in 55% of the tile
Brazed joint → OK
Lack of bonding at the edge

7. Brazing tests (Microscopy)

8. Brazing tests (Program)
Brazing at low temperature
Au-Ge Alloy at 356 °C
Brazing with grooves
Ag-Cu-Ti Alloy at 780°C
Brazing with a molybdenum sheet
Stress absorber
Ultrasounds + Microscopy + Mechanical tests