Improvement of thermal shock resistance of isotropic graphite by Ti-doping

Abstract

Ti-doped isotropic graphite is a promising candidate material for the strike point area of the ITER divertor due to its reduced chemical erosion by hydrogen bombardment and its high thermal shock resistance, mainly due the catalytic effect of TiC on the graphitization leading to an increase of thermal conductivity and to higher mechanical strength. Several manufacturing parameters such as oxidative stabilization treatment, carbonization cycle, graphitization temperature and dwell time during graphitization have been investigated in order to establish a relationship between these parameters and the final properties.

Compilation of erosion yields of metal-doped carbon materials by deuterium impact from ion beam and low temperature plasma

“…Due to variation of the process parameter, the properties of the graphites were optimized, especially in respect of homogeneity of doping, thermal conductivity and flexural strength. Thermal conductivity above 150 W/mK and homogeneous dopant distribution on the 50 µm length scale were achieved by both producers [15,18]. The optimized materials 4 were used for mock-up manufacturing, on which HHF tests were performed [18].…”

“…In recent mock-up manufacturing and high heat flux (HHF) tests, the feasibility and reliability of the newly developed carbon-based materials and the corresponding joining technology to a Cu-based heat sink were shown [14,15,16,17,18]. Note that the properties of the tested materials cannot be found at present in any commercial graphite.…”

Ti-doped isotropic graphite: A promising armour material for plasma-facing components

“…Ti was introduced in form of TiC nanopowder (Sigma Aldrich) with an average particle size of 130 nm. The carbide was added to the carbon raw powder so as to obtain a final 13th International Conference on Fusion Reactor Materials (ICFRM- 13) 10.-14. December 2007, Nice, France graphitic material with ~4 at.% Ti.…”

“…The average particle size of the initial SiC powder was 20 nm. The manufacturing procedure and the material characterization are described in detail in [13]. In Table 1 some typical properties of the manufactured materials (undoped, Ti-doped and Ti-Si-doped) after graphitization at 2765°C are shown.…”

“…In Table 1 some typical properties of the manufactured materials (undoped, Ti-doped and Ti-Si-doped) after graphitization at 2765°C are shown. It can be observed that the addition of a small amount of SiC results in thermal conductivities at room temperature (RT) close to 200 W/mK, but care has to be taken during graphitization to avoid swelling and cracking due to a fast Si evaporation [13]. On the other hand, for samples doped with only TiC a proper choice of the graphitization parameters [13] leads to even higher thermal conductivity values, avoiding the problems arising from Si evaporation during graphitization.…”