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

Mechanical behaviour of Diamond MMCs Young’s modulus:4-point bending strength: kHz Samples: ≈4x5.5x60 mm Modulus at RT, average of two modes Samples as for Young’s modulus Bending strength at RT

CTE of SIC Measurement parameters: 2 cycles 50…950°C Heating/cooling rate 5 Kmin -1 Holding time at extremes: 20 min Physical CTE approximated by a 2 nd order polynomial

Results on Mechanical behaviour of Diamond MMCs: Bending strength Ag-Si-D with >500 MPa bending strength (particle size 45 µm) CuD with a bending strength around 130 MPa (some plasticity, elastic limit much lower). Particle size 200 µm. AlD bending strength <30 MPa with large plastic deformation. Particle size 45 µm.

Results on Mechanical behaviour of Diamond MMCs: Young’s modulus MaterialVol. frac.Young’s modulus [GPa] Bending strength [MPa] Al_Diamond_ Al_Diamond_ Al_Diamond_ Cu_Diamond_ Cu_Diamond_ Ag-Si_Diamond_ Ag-Si_Diamond_ Ag-Si_Diamond_ Low and very high volume fractions for Al and Cu-diamond composites, respectively, indicate presence of significant amounts of porosity

Results: CTE of SIC Samples Cis 1 and Cis 2

Results: CTE of SIC Sample traction

Results: CTE of SIC Sample CVD by Microcertec; z-direction is the growth direction CTE in-plane quite isotropic, somewhat lower in growth direction.

Results: CTE of SIC—comparison to literature Measurements on the present samples are significantly below literature values CTE best described by

Ag-Si_Diamond composites have promising properties Al- and Cu- based diamond composites suffer from porosity It may be interesting to evaluate the mechanical properties especially bending strength as a function of the diamond size. The CTE of SiC measured here is lower than the values indicated in the literature. Conclusion & Outlook