Plasma-assisted preparation of nano-(ZrC, ZrO2)@carbon composites from Zr-loaded sulfonated styrene–divinylbenzene copolymers

Alejandro Martiz,Laura Bereczki,Zoltán Károly,Rajendra P Pawar,Sunil Tekale,Alfréd Menyhárd,László Trif,Péter Németh,Zsombor Molnár,László Kótai,Miklós Mohai

doi:10.1007/s10973-022-11236-4

Abstract

We have developed a simple method to prepare nano-(ZrC0.93, ZrO2-polymorphs)@carbon composites with graphite/amorphous carbon content and adjustable Zr/C ratio based on using a multistep tube furnace and plasma-assisted heat treatment of zirconium-loaded sulfonated styrene–divinylbenzene (STY-DVB) copolymers. Pre-pyrolysis of zirconium-loaded sulfonated STY-DVB ion exchangers with 2 and 8 mass % DVB at temperatures between 1000 and 1400 °C for 2 h produced nano-ZrO2@C intermediates with particle sizes of ~ 30–60 nm with no ZrC formation. Plasma processing of nano-ZrO2@C resulted in nano-(ZrC0.93, ZrO2)@C composites with 11% (under a He atmosphere) (C/Zr = 73) or 13% (under a H2 atmosphere) (C/Zr = 58) ZrC0.93 content. Three polymorphs of the zirconium dioxide (tetragonal, monoclinic and cubic, between 18 and 27 nm) were found in the products. The amounts of tetragonal and monoclinic ones are comparable to that of ZrC0.93. The average particle size of ZrC0.93 prepared in this way was found to be 21–23 nm. The BET surface area of the nano-(ZrC0.93, ZrO2)@C(graphite) composites prepared in He and H2 was over 250 and 300 m2/g, respectively. We developed a reproducible and easy method to prepare nano-(ZrC, ZrO2)@C products by setting the DVB content, sulfonation degree, Zr loading and the thermal treatment conditions, which have an influence on the ZrC and graphite/amorphous carbon content of nano-ZrO2@C intermediates. The zirconium-loaded sulfonated styrene–divinylbenzene (STY-DVB) copolymers (2 and 8 mass% DVB) or their thermal decomposition was characterized with vibrational spectroscopy, thermal analysis and DSC or powder XRD, BET, XPS and HRTEM methods, respectively.

Highlights

Zirconium carbide–carbon (ZrC@C) composites have been considered strategic materials in emitters and coatings for nuclear reactor fuels due to their high melting point, good mechanical properties, small neutron absorption cross section, high sorption capacity and radiolytic stability toward radioactive isotopes [1,2,3,4]
Scales et al synthesized porous, mechanically stable bead-like ZrC@C composites via carbothermal reduction of polyacrylonitrileZrCl4 composites [3] and quaternary ammonium salt group containing styrene–divinylbenzene copolymers loaded with anionic zirconium complexes [4]
We have developed a simple method to prepare nano(ZrC0.93, ZrO2 polymorph)@carbon composites with adjustable Zr/C ratio in two-step pyrolysis of zirconium-loaded sulfonated styrene(STY)-divinylbenzene(DVB) copolymers

Summary

Introduction

Zirconium carbide–carbon (ZrC@C) composites have been considered strategic materials in emitters and coatings for nuclear reactor fuels due to their high melting point, good mechanical properties, small neutron absorption cross section, high sorption capacity and radiolytic stability toward radioactive isotopes [1,2,3,4]. These results prompted us to develop the preparation of nano-ZrO2@C intermediates from Zr-loaded sulfonated STY-DVB copolymers so that we could study their direct transformation in RF thermal plasma into nano-ZrC@C materials.

Results

Conclusion