Fabrication of Tantalum and Hafnium Carbide Fibers via ForcespinningTM for Ultrahigh-Temperature Applications

Harold O Lee,Avi G Bregman,Marissa Ringgold,Patricia H Caraballa,James R Nicholas,Nelson S Bell,Larico J Treadwell,Patrice Berthod

doi:10.1155/2021/6672746

Abstract

In this work, a novel method for producing ultrafine tantalum and hafnium carbide fibers using the ForcespinningTM technique via a nonhalide-based sol-gel process was investigated. An optimal solution viscosity range was systematically determined via rheological studies of neat PAN/DMF as a function of fiber formation. Subsequently, ForcespinningTM parameters were also systemically studied to determine the optimal rotational velocity and spinneret-to-collecting rod distance required for ideal fiber formation. TaC and HfC fibers were synthesized via ForcespinningTM utilizing a mixture of PAN and refractory transition metal alkoxides (i.e., tantalum (V) ethoxide and hafnium (IV) tert-butoxide) in DMF solution based on optimal conditions determined from the neat PAN/DMF. In all instances after calcination, powder X-ray diffraction (PXRD) and energy dispersive spectroscopy (EDS) indicated that TaC and HfC fibers were produced. TGA/DSC confirmed the chemical stability of the resulting fibers.

Highlights

While refractory transition metal-carbides (RTM-Cs) have been studied as far back as the 1800s, interest in these materials increased in the late 1950s as the space race intensified [1]
RTM-C materials possess strong covalent bonding and degrees of metallic bonding that lead to high melting points (>3700°C (4000 K)), high hardness, good high-temperature strength, high resistance to oxidation, excellent electrical conductivity, and exceptional resistance to harsh chemical and thermal environments [2, 5,6,7]. is combination of properties allows RTM-Cs to survive in more extreme environments than that of existing structural materials
TaC and HfC fibers have been successfully synthesized via the ForcespinningTM method. e rheology of the varying wt % of PAN and DMF was determined to understand the entanglement and optimize the precursor solution for fiber formation. is surrogate sample solution led to the optimal fiber solution parameters to produce RTM-C fibers. e RTM-C fibers were characterized in order to confirm their formation, crystal structure, and stability

Summary

Introduction

While refractory transition metal-carbides (RTM-Cs) have been studied as far back as the 1800s, interest in these materials increased in the late 1950s as the space race intensified [1]. Erefore, materials that can survive/mitigate these extreme environments are critical for the future application of hypersonic technologies. Silicon carbide (SiC) fibers have been investigated as a replacement for carbon fibers. Due to the thermal limitation of carbon and silicon carbide fibers handicapping ultrahigh-temperature performance, RTM-C materials for use in high-temperature environments have been identified as viable replacements [4]. RTM-C materials possess strong covalent bonding and degrees of metallic bonding that lead to high melting points (>3700°C (4000 K)), high hardness, good high-temperature strength, high resistance to oxidation, excellent electrical conductivity, and exceptional resistance to harsh chemical and thermal environments [2, 5,6,7]. Is combination of properties allows RTM-Cs to survive in more extreme environments than that of existing structural materials RTM-C materials possess strong covalent bonding and degrees of metallic bonding that lead to high melting points (>3700°C (4000 K)), high hardness, good high-temperature strength, high resistance to oxidation, excellent electrical conductivity, and exceptional resistance to harsh chemical and thermal environments [2, 5,6,7]. is combination of properties allows RTM-Cs to survive in more extreme environments than that of existing structural materials

Methods

Results

Conclusion