Crush strength of silicon carbide coated TRISO particles: Influence of test method and process variables

•Crush strength is strongly dependent on the anvil hardness.•Soft anvil crush strength is more sensitive to particle properties than hard anvil crush strength.•Crush strength of SiC coated particles is influenced by the inner pyrocarbon.•Crush strength depends on SiC thickness, deposition temperature and coater design.•MTS concentration and carrier gas flow rate did not influence crush strength. The influence of deposition temperature, methyl trichlorosilane (MTS) concentration, hydrogen carrier-gas flow rate and gas inlet design on the strength of silicon carbide coated TRISO particles was investigated using whole particle crushing strength. Crush strength was measured using soft aluminium anvils. For comparison a selection of particles were also measured with hard anvils. The influence of silicon carbide thickness was determined to allow for normalisation of all crush strength measurements to a crush strength at an equivalent thickness of 35μm. It was found that the strength of the underlying pyrocarbon coated particles had a significant influence on the crush strength of the silicon carbide coated particles. Deposition temperature and gas inlet design were the only process parameters that influenced the coated particle crush strength. No evidence was found for MTS concentration and hydrogen flow rate having any influence on particle crush strength.