Synthesis studies of radiation dense Reactive Sintered Borides (RSB) nuclear shielding materials

Abstract

Reactive Sintered Borides (RSBs), a candidate neutron-radiation shielding material were successfully synthesized by vacuum and argon atmosphere sintering to determine an RSB-specific sintering process to demonstrate their reproducibility and their potential as tractable nuclear fusion radiation-shielding materials. Sintering conditions specifically for RSB synthesis were determined from this work to reproduce dense RSBs fabricated using Ar/H2 SinterHIPPing. DTA/TGA, mass-spectrometry and vacuum sintering studies determined that RSBs outgas more during early sintering. CALPAD determined that RSBs require high temperature (T > 1430 °C) for densification without SinterHIPP. Vacuum sintering studies investigated outgassing of samples and observed that RSBs have a broad outgassing peak around 650 °C not observed for cWCs, attributed to loss of H and O at higher temperatures. Dense Gen 2 RSB55 samples (ρ/ρXRD,RSB55 > 95%) were synthesized under flowing Ar at 1450 °C. Gen 2 samples had finer microstructure and more WC presence relative to Gen 1, alongside higher hardness and more consistent hardness values with less porosity relative to Gen 1. This study demonstrates that radiation dense RSB materials are reproducible and identifies pathways to future synthesis of RSBs.