Machining and corrosion studies on HfC reinforced ZE41 magnesium matrix composites

In this paper, Hafnium Carbide (HfC) reinforced ZE41 Magnesium Matrix Composites (MMCs) were prepared by using stir casting method. Using three different reinforcement percentages of HfC such as 5%, 10% and 15% by wt., ZE41-HfC MMCs were prepared. The mechanical characteristics of ZE41-HfC MMCs were evaluated by subjecting them to tensile and surface micro-hardness studies. Using X-Ray diffraction (XRD) studies, chemical compounds formed in the interfacial layer between HfC & ZE41 Mg was observed. Using optical microscopy (OM) and scanning electron microscopy (SEM), the surface modifications in the composites due to HfC addition was studied. Using electron backscatter diffraction analysis (EBSD), the changes in particle grain sizes and orientation of ZE41-HfC MMCs were studied. Energy Dispersive Spectroscopy (EDS) analysis was used to identify the variations in elemental composition of the prepared ZE41-HfC MMCs. ZE41-HfC MMCs were subjected to drilling studies for identifying the variations in cutting forces. Using electrochemical studies, the corrosion resistance of ZE41-HfC MMCs was observed. SEM images of corroded ZE41-HfC MMCs revealed micro cracks and dense pits near HfC agglomerated region.

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

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.