Simulation of Neutron/Self-Emitted Gamma Attenuation and Effects of Silane Surface Treatment on Mechanical and Wear Resistance Properties of Sm₂O₃/UHMWPE Composites

This work reports on the simulated neutron and self-emitted gamma attenuation of ultra-high-molecular-weight polyethylene (UHMWPE) composites containing varying Sm₂O₃ contents in the range 0-50 wt.%, using a simulation code, namely MCNP-PHITS. The neutron energy investigated was 0.025 eV (thermal neutrons), and the gamma energies were 0.334, 0.712, and 0.737 MeV. The results indicated that the abilities to attenuate thermal neutrons and gamma rays were noticeably enhanced with the addition of Sm₂O₃, as seen by the increases in µ_m and µ, and the decrease in HVL. By comparing the simulated neutron-shielding results from this work with those from a commercial 5%-borated PE, the recommended Sm₂O₃ content that attenuated thermal neutrons with equal efficiency to the commercial product was 11-13 wt.%. Furthermore, to practically improve surface compatibility between Sm₂O₃ and the UHMWPE matrix and, subsequently, the overall wear/mechanical properties of the composites, a silane coupling agent (KBE903) was used to treat the surfaces of Sm₂O₃ particles prior to the preparation of the Sm₂O₃/UHMWPE composites. The experimental results showed that the treatment of Sm₂O₃ particles with 5-10 pph KBE903 led to greater enhancements in the wear resistance and mechanical properties of the 25 wt.% Sm₂O₃/UHMWPE composites, evidenced by lower specific wear rates and lower coefficients of friction, as well as higher tensile strength, elongation at break, and surface hardness, compared to those without surface treatment and those treated with 20 pph KBE903. In conclusion, the overall results suggested that the addition of Sm₂O₃ in the UHMWPE composites enhanced abilities to attenuate not only thermal neutrons but also gamma rays emitted after the neutron absorption by Sm, while the silane surface treatment of Sm₂O₃, using KBE903, considerably improved the processability, wear resistance, and strength of the composites.