Boron carbide as a target for the SPES project

Within the framework of the research on targets for the SPES project (Selective Production of Exotic Species), porous boron carbide (B4C) based materials were produced from the carbothermal reduction of boric acid and two different carbon sources, i.e. citric acid and phenolic resin. Samples composition and microstructural morphology were studied by means of X-ray diffraction spectrometry (XRD) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). The amount of total porosity was obtained from the comparison between the theoretical density and the measured bulk density. To better characterize the material microstructure, nitrogen physisorption measurements were performed in order to obtain data about the type of generated porosity and the specific surface area of the samples. Analysis performed on the samples show that after the final thermal treatment they are composed of boron carbide and residual free carbon, whose quantity is related to the processes involved in the two synthesis. Remarkable differences in the overall weight loss have been noticed for the two different reactions, resulting in different densities and pore size distributions, but in both cases similar values of specific surface area (SSA) were obtained.