1. Diamond based Composites for Collimators Contribution to EuCard
L. Weber
Laboratory for Mechanical Metallurgy Ecole Polytechnique Fédérale de Lausanne (EPFL)
CH-1015, Lausanne, Switzerland

2. Liquid metal infiltration process
Alternative routes:
hot pressing of powder mixtures
hot pressing of coated particles

3. Pressure infiltration apparatus
Cold wall vessel (250 bar, 200°C) Inner side of the wall in contact with a water cooled heat shield
Induction heating (using a graphite susceptor)
primary vacuum pump (0.1 mbar)
Crucible can be lowered on quench (directional solidification)
100 mm

4. Selected diamond grit Mono-crystalline diamond Low nitrogen level
Relatively large size (>100µm)

5. Critical issues Diamond particle size: the larger the better the TC
Limited machinability => Need for net-shape solutions
Size of the net-shape parts
Radiation damage in Diamonds
CTE varies strongly with temperature
Electrical conductivity rather low (5-10 MS/m)

6. Materials & parts Diamond composites: 60-75 vol-% diamond + Al, Ag, Cu
Parts: fabrication capacity established for plates in Ag-Si diamond and Al-diamond
size: 80*300*10 mm3
Expected thermal conductivity
>800 W/mK for Ag-Si composites
>600 W/mK for Al based composites

7. First results: CTE
Cu-B composites:

8. First results: CTE
Ag-3Si composites:

9. Other tasks Brazing of SiC on diamond composites
Thermal fatigue of SiC brazed on substrate
Mechanical tests
Thermal conductivity measurement:
3 setups: 0-40°C, K, K