Platinum Powder Research Articles

Global platinum powder market to attain revenue of $84.4 M by 2030, propelled by rising demand across diverse industrial sectors

Global platinum powder market to attain revenue of $84.4 M by 2030, propelled by rising demand across diverse industrial sectors

Iridium on Conductive Support: Towards Low Iridium Anodes in PEM Electrolyzers

Commercialization of proton exchange membrane (PEM) electrolyzers for green hydrogen production have been recently achieved, but with a limited scale of low gigawatts (GW).1 Large-scale and sustainable deployment of PEM electrolyzers will face the challenges of scarcity and high cost of iridium (Ir) used in the anode to catalyze oxygen evolution reaction (OER). A 1 MW PEM electrolyzer stack currently uses ~0.4 kg of Ir based on an Ir loading of 1.5 mg/cm2, which contributes ~$60k cost per stack.2 Moreover, the Ir production has been about 8 tons/year in recent years.3 This can only support an annual production of 5 GW PEM electrolyzer if assuming 25% Ir is available for PEM electrolyzers with the same Ir loading. Therefore, lowering the Ir loading in PEM electrolyzers is urgently needed to meet the rapid expansion of the PEM electrolysis market.Several groups including Plug have developed supported Ir catalysts to lower the Ir loading by a factor of 5 without sacrifice in efficiency.4-8 However, all support used by far is non- or poorly electrically conductive. The conductivity of the electrodes relies solely on the surface IrOx, which sets stringent limits on the catalyst/electrode development, especially with low Ir contents. Here we first argue from fundamental aspects that the catalysts/electrodes with Ir on conductive support can be free of these limits. We further show that platinum (Pt) and titanium diboride (TiB2) powders are feasible candidates as conductive support for Ir-based OER catalysts. We demonstrated a TiB2 supported IrOx (IrOx/TiB2) catalyst synthesized via wet chemistry deposition without post heat treatment combines a mass activity towards OER with high conductivity. Its conductivity of ~30 S/cm2 is comparable to that of Vulcan carbon, and ~105 times that of the counterpart IrOx/W-TiO2 (W-TiO2 represents commercial tungsten doped TiO2 nanoparticles). Meanwhile, the IrOx/TiB2 catalyst shows a mass activity comparable to that of the counterpart IrOx/W-TiO2, twice that of commercial Ir black, and 50 times that of a commercial IrO2/TiO2 catalyst in acidic solution. Durability test showed that the Ir dissolution of the IrOx/TiB2 in acidic solution holding at 2 V for 100 hours is comparable to that of Ir black. Characterization of the IrOx/TiB2 showed small hydrous IrOx nanoparticles (1-2 nm) uniformly distributed on the surface of TiB2 nanoparticles (~58 nm) with an Ir content of ~33±7 wt%. Membrane electrode assembly evaluation on the IrOx/TiB2 catalyst is undergoing. The results will be reported and discussed. References (1) IEA, World Energy Outlook, 2022. https://iea.blob.core.windows.net/assets/830fe099-5530-48f2-a7c1-11f35d510983/WorldEnergyOutlook2022.pdf (accessed 2023-02-12).(2) Mittelsteadt, C. (Invited) Ir Strangelove: Or How I Learned to Stop Worrying and Embrace the PEM. ECS Meeting s 2022, MA2022-01, 1335-1335.(3) Seeking Alpha Home Page. https://seekingalpha.com/article/4399727-sibanye-should-benefit-from-hydrogen-wars-thanks-to-iridium-exposure (accessed 2023-02-12).(4) Böhm, D.; Beetz, M.; Gebauer, C.; Bernt, M.; Schröter, J.; Kornherr, M.; Zoller, F.; Bein, T.; Fattakhova-Rohlfing, D. Highly conductive titania supported iridium oxide nanoparticles with low overall iridium density as OER catalyst for large-scale PEM electrolysis. Applied Materials Today 2021, 24, 101134.(5) Pham, C. V.; Bühler, M.; Knöppel, J.; Bierling, M.; Seeberger, D.; Escalera-López, D.; Mayrhofer, K. J. J.; Cherevko, S.; Thiele, S. IrO2 coated TiO2 core-shell microparticles advance performance of low loading proton exchange membrane water electrolyzers. Appl. Catal. B‐Environ. 2020, 269, 118762.(6) Zhao, S.; Stocks, A.; Rasimick, B.; More, K.; Xu, H. Highly Active, Durable Dispersed Iridium Nanocatalysts for PEM Water Electrolyzers. J. Electrochem. Soc. 2018, 165, F82-F89.(7) Oakton, E.; Lebedev, D.; Povia, M.; Abbott, D. F.; Fabbri, E.; Fedorov, A.; Nachtegaal, M.; Copéret, C.; Schmidt, T. J. IrO2-TiO2: A high-surface-area, active, and stable electrocatalyst for the oxygen evolution reaction. ACS Catal. 2017, 7, 2346-2352.(8) Lewinski, K. A.; van der Vliet, D.; Luopa, S. M. NSTF advances for PEM electrolysis-the effect of alloying on activity of NSTF electrolyzer catalysts and performance of NSTF based PEM electrolyzers. ECS Trans 2015, 69, 893.

Modification of Pt-Porous Composite Material (Pt-PCM) and Its Application for Electroanalysis of Uric Acid and Electrosynthesis of Acetic Acid from Ethanol

Research on the synthesis of Pt-Porous Composite Material (Pt-PCM) has been done. This material is used for the electrochemical activity of uric acid and electrochemical synthesis of acetic acid from ethanol. Pt-PCM is made by mixing 99.995% platinum powder and PVC or Poly (vinyl chloride) homogeneously with a homogenizer for 3.0 h, plus tetrahydrofuran solvent, and pressed with a strength of 10 tons/cm2. The material produced was analysis using Scanning Electron Microscopy (SEM), voltammetry potential V and Tafel plot. The material is used as an electrode for the determination of uric acid and the synthesis of acetic acid from ethanol. The results showed that Pt-PCM has evenly distributed pores and has a perfect Tafel slope compared to metal platinum or solid platinum. Pt-PCM also has the excellent ability as a working electrode for the analysis of uric acid in human urine and electro synthetic acetic acid from alcohol. In conclusion, Pt-Porous Composite Material (Pt-PCM) is a porous material, so it is excellent as a candidate for electrodes.

Pore Forming Agent–Assisted Fabrication of Porous Platinum Vent Frits and Their Suitability Evaluation for Radioisotope Power Sources

Disc-shaped porous platinum sintered frits were fabricated employing a pore forming agent (PFA) via a powder-metallurgical process. Porous vent frits using several platinum-PFA compositions were prepared after characterizing the starting materials (platinum and PFA powders) for particle size (D50) and distribution (D10 to D90), morphology, Brunauer-Emmet-Teller surface area, density (apparent and tap), etc. The sintered platinum vent frits were extensively characterized to evaluate their suitability for application in terms of surface microstructure analysis by scanning electron microscopy, helium/air permeability parameters, and particulate filtration characteristics. This paper reports for the first time on the measurement of retention efficiency of vent frits for particulate sizes 0.3, 0.5, and 1 µm. The platinum frits made using 10 and 20 vol % PFA were found to be suitable as a vent hole filter for radioisotope power sources.

Parametric X-ray radiation from nanopowders

The first observation of Parametric X-ray Radiation (PXR) produced in a crystalline powder constituted of crystallites whose largest dimensions are of the order of some nanometers is reported. PXR was registered during the interaction of a 7 MeV electron beam with a platinum powder. The experimental results were compared with the kinematical theory showing a good agreement concerning the position, form, and intensity of all observed PXR spectral peaks. Finally, an analysis of the influence of crystallite dimensions on the PXR peak full width hall maximum (FWHM) and PXR peak intensity was performed.

Synthesis of Platinum-Rare Earth Metal Alloy Catalysts for Proton Exchange Membrane Fuel Cells

Electrocatalysts for low temperature fuel cells are based on noble metals and can be promoted by development of alloys of platinum with e.g. late transition metals such as Ni and Co.[1,2] It has been reported that Pt alloys with rare earth (RE) metals exhibit remarkable activity and high stability towards the oxygen reduction reaction.[3] Due to the very low standard reduction potentials and high oxophilicity of rare earth metals, preparation platinum alloys in form of nanoparticles meets great challenges for chemical routes of co-reduction. A one-step method is recently developed to prepare Pt−RE nanoalloys from a mixture of solid state precursors consisting of metal halides in their hydrate forms, a suitable nitrogen-rich compound and a carbon support.[4,5] The synthesis involves in situ formation of a carbon-nitrogen network, onto which the two metals are atomically dispersed. The coordination with nitrogen sites stabilizes the metals, which, upon thermal decomposition under a mild reducing atmosphere, leads to the formation of Pt-RE nanoalloys. The carbon support is introduced either as carbon blacks or carbon supported platinum powder. The pre-formed, either in or ex situ, platinum nanoparticles, facilitates the reduction of rare earth metals thermodynamically driven by the negative alloying free energy. A series of pure crystal phases such as Pt5RE (e.g. La, Ce, Nd), and Pt3RE (e.g. Y, Gd, Tb) have been synthesized in form of carbon supported nanoparticles with tunable metal loadings and alloy particle sizes. One of the typical catalysts is the Pt5Ce/C in a metal to carbon ratio of 30 wt% and an average alloy particle size of ca. 5.5 nm which exhibits an area specific activity of 3.7 times and a mass activity of 1.9 times higher than those of the Pt/C analogue. Further understanding and improvement of the process are in progress and the updated results will be presented in this talk.[1]. J. K. Norskov et al., Nature Chemistry 1, 37-46 (2009)[2]. X. Q. Huang et al., Science 348, 1230-1234 (2015)[3]. M. Escudero-Escribano et al., Science 352, 73-76 (2016)[4]. Y. Hu et al., J. Am. Chem. Soc. 142, 953–961 (2020)[5]. Y. Hu et al., Chem. Mater. 33, 2, 535–546 (2021)

Synthesis of diamond crystal growth on tungsten carbide inserts by HFCVD using various seeding powders.

The hot filament chemical vapor deposition (HFCVD) process is used to synthesize diamond crystals on cemented carbide (WC–Co) SPUN inserts. Diamond (Dia.), carbon (GC-glassy spherical form), iridium (Ir), molybdenum (Mo), palladium (Pd), platinum (Pt), tungsten (W), and tantalum (Ta) powders were used as seeding materials for crystal growth. Scanning electron microscopy (SEM) data revealed the development of a few diamond crystals in platinum, iridium, and tungsten powders. The seeding with carbon, tantalum, and diamond powders formed clustered microcrystalline diamond (MCD) crystals, although other powders produced discrete crystals. Tantalum and diamond-seeded powders produced the most significant number and size of crystals. According to micro-Raman spectroscopy (µ-RS), tantalum powder had the lowest ID/IG ratio and the most excellent sp3 bonding. X-ray diffraction (XRD) revealed the maximum diamond intensity in the (111) plane. According to atomic force microscopy (AFM), diamond and molybdenum powders had the largest grains, whereas tantalum powder had the smallest root mean square roughness value with a homogeneous grain distribution. The Vickers microhardness (VHN) test confirmed the highest hardness value for diamond and tantalum seeded powder coatings with the least amount of radial cracking. Field emission scanning electron microscopy (FESEM) revealed that both powders had higher film thickness values.

Biological methane production coupled with sulfur oxidation in a microbial electrosynthesis system without organic substrates

Methane is produced in a microbial electrosynthesis system (MES) without organic substrates. However, a relatively high applied voltage is required for the bioelectrical reactions. In this study, we demonstrated that electrotrophic methane production at the biocathode was achieved even at a very low voltage of 0.1 V in an MES, in which abiotic HS− oxidized to SO42− at the anodic carbon-cloth surface coated with platinum powder. In addition, microbial community analysis revealed the most probable pathway for methane production from electrons. First, electrotrophic H2 was produced by syntrophic bacteria, such as Syntrophorhabdus, Syntrophobacter, Syntrophus, Leptolinea, and Aminicenantales, with the direct acceptance of electrons at the biocathode. Subsequently, most of the produced H2 was converted to acetate by homoacetogens, such as Clostridium and Spirochaeta 2. In conclusion, the majority of the methane was indirectly produced by a large population of acetoclastic methanogens, namely Methanosaeta, via acetate. Further, hydrogenotrophic methanogens, including Methanobacterium and Methanolinea, produced methane via H2.

Bioelectrical Methane Production with an Ammonium Oxidative Reaction under the No Organic Substance Condition.

The present study investigated bioelectrical methane production from CO2 without organic substances. Even though microbial methane production has been reported at relatively high electric voltages, the amount of voltage required and the organisms contributing to the process currently remain unknown. Methane production using a biocathode was investigated in a microbial electrolysis cell coupled with an NH4+ oxidative reaction at an anode coated with platinum powder under a wide range of applied voltages and anaerobic conditions. A microbial community analysis revealed that methane production simultaneously occurred with biological denitrification at the biocathode. During denitrification, NO3– was produced by chemical NH4+ oxidation at the anode and was provided to the biocathode chamber. H2 was produced at the biocathode by the hydrogen-producing bacteria Petrimonas through the acceptance of electrons and protons. The H2 produced was biologically consumed by hydrogenotrophic methanogens of Methanobacterium and Methanobrevibacter with CO2 uptake and by hydrogenotrophic denitrifiers of Azonexus. This microbial community suggests that methane is indirectly produced without the use of electrons by methanogens. Furthermore, bioelectrical methane production occurred under experimental conditions even at a very low voltage of 0.05‍ ‍V coupled with NH4+ oxidation, which was thermodynamically feasible.

Flexible carbon monoxide sensor for environmental detection of small‐scale robot

With the advancement and development of science and technology, the detection role of small-scale robot has become increasingly prominent, especially for environmental detection in hazardous situations such as explosion and fire. In this study, to realise the detection of carbon monoxide gas in hazardous locations, a flexible carbon monoxide sensor consisting of polyimide, interdigital electrode, and composite film is proposed and designed, which has the advantages of simple structure, high sensitivity, good flexibility, and low cost. For the interdigital electrode, the distance between the electrodes and the width of the electrode is both 50 μm, and the sizes of the polyimide substrate and the electrode area are 1.5 × 4 cm2 and 1 × 1 cm2, respectively. The composite film is made by mixing single-walled carbon nanotubes and platinum powders. The test results show that the sensitivity of the sensor is 0.0201 Ω/ppm in the range of 0–100 ppm at room temperature with a linear fit of 94.63%.

Iron activity measurements and spinel-slag equilibria in alumina-bearing iron silicate slags

Alumina is a common substance deporting in copper smelting slags when various secondary copper fractions, e.g. e-scrap or WEEE, are used as feedstock as such or along with primary sulphide concentrates. Properties of iron-silicate slags at high alumina concentrations, in the iron-alumina spinel saturation, have been studied at 1300 °C by a high temperature equilibration-quenching method combined with EPMA (electron probe microanalysis) phase composition data from the polished sections. The equilibrations were performed in fixed oxygen activity with platinum or palladium powder, which dissolved iron from the slag and generated a heterogeneous equilibrium system, characterised by the general equilibrium criterium in isothermal and isobaric conditions, as.μalloy(Fe) = μslag(Fe) = μspinel(Fe).This criterium was used for measuring experimentally iron activities of molten silicate slags. The locations of the spinel-liquid slag tie-lines were also determined in the oxygen partial pressure range of 10−6–10−10 atm. A comparison with the recent critical thermodynamic assessments of the Fe–O–Al2O3 system indicates that the iron-alumina spinel-corundum phase boundary in silica-containing systems as a function of oxygen partial pressure is too steep and thus the assessed databases do not match with the experimental data of this study. The liquid slag domain from silica to iron oxide saturation is also smaller than expected earlier, as the spinel primary phase boundary locates at higher silica concentrations than e.g. obtained in the assessments of the Mtox database.

The effect of transition-metal seeding powder on deposition and growth of diamond synthesized by hot filament chemical vapor deposition processes on cemented carbide substrates and its characterization

Hot Filament Chemical Vapor Deposition is a well-established method to synthesize diamond thin films on a non-diamond substrate. Here, we have deposited microcrystalline diamond on tungsten carbide cutting tool insert by using conventional Hot Filament Chemical Vapor Deposition technique. The substrates were ultrasonically seeded with Carbon, Diamond, Iridium, Molybdenum, Palladium, Platinum, Tantalum, Tungsten and Chromium natural powders and thereafter were deposited with the same deposition parameters to observe the effects of different seeding powders on the diamond coating. The coated tools were characterized by X-ray Diffraction and the quality of diamond crystals was assessed by using micro Raman spectroscopy. The surface morphology was studied by utilizing Scanning Electron Microscope. The discrete spherical diamond crystals were formed with carbon powder seeding while very dense along with uniform coatings were deposited on the diamond powder seeded substrate. Larger diamond crystals with good density were observed on the palladium seeded substrate. The micro Raman spectroscopy showed mixed results of sp3 and sp2 bonding. But the palladium seeding showed clear sp3 bonding due to the formation of crystals with bigger size. The Vickers microhardness value for the substrate with diamond seeding was found to be much higher than other coated tools.

Characterization of Micro-Crystalline Diamond Tools Synthesized by HFCVD Process with Different Seeding Powders

Synthesis of diamond films on carbide insert is a recent area of research in surface engineering. This research is carryout to know the effect of different seeding powders on diamond coating of WC tool by Hot Filament Chemical Vapor Deposition (HFCVD) method. Here, the formation of microcrystalline diamond (MCD) on SPUN tungsten carbide (WC-Co) cutting tool insert is carried out. Basically, before coating in HFCVD method, the substrate cobalt content should minimize by ultra-sonic etching. The uncoated tools are seeded ultrasonically by Diamond, Iridium, Platinum and Tungsten powder at the same coating condition to observe the growth of diamond crystals. X- ray diffraction gives clear results of diamond plane and adhesion of coating. The purity of diamond crystal after coating can be clear by observing the Raman shift in Raman spectroscopy (RS). The tool is seeded with diamond powder gives more nucleation density due to the presence of more sp3 bond as compared with sp2. Use of diamond and platinum powder as a seeding material gives fully developed crystal and uniform coating during diamond film deposition by HFCVD technique, rather in case of other powder coating the discrete crystals were formed.

Determination of platinum group elements in catalysts recycling products by SEM with energy dispersive spectrometer

Analysis of platinum group elements (PGE) extracted from various catalysts used in the car, petroleum and chemical industries requires use of microanalytical methods. PGE content in the platinum powder concentrates K176 and K177 was studied by SEM-EDS. The content of main elements was determined using analytical lines Fe Kα1, Si Kα1, Sn Lα1, Pt Lα1, Re Lα1. The obtained data for the chemical composition are in good agreement with the result obtained by X-ray fluorescence analysis and ICP-MS method. Powdered platinum concentrates are considered to be ferrosilicide (FeSi), where PGE are localized at the phase boundaries and in separate patches of the K176 sample, or distributed over the volume of particles in the K177 sample.

Palladium-Coated Platinum Powders with Tunable, Nanostructured Surfaces for Applications in Catalysis

Simultaneous control of nanoscale surface morphology and composition remains a challenge in preparing bimetallic catalysts, particularly at the large scale required for industrial application and with high-surface-area substrates. Atomic layer electroless deposition (ALED) is a scalable approach to prepare surface-modified metal powders in which elements more noble than the surface hydrides of the substrate metal are deposited layer-by-layer in a surface-limited fashion. Herein we demonstrate that high-surface-area Pt powder is a viable substrate for controlled deposition of Pd adlayers using this technique, with the potential for large-scale preparation, for use in electrocatalytic and catalytic applications such as fuel cells and functionalization of petrochemical feedstocks. Two different growth mechanisms have been proposed based on bulk and surface Pd atomic fractions obtained from atomic absorption spectroscopy and X-ray photoelectron spectroscopy, respectively. Further, spectral simulations were pe...

Separation and Recovery of Platinum and Palladium from Spent Petrochemical Catalysts Using Activated Carbon, Analysis of Two Kind of Most Used Catalysts in Petro Chemistry

The goal of this work is the separation and recovery of platinum and palladium from spent catalyst. The recovery consisted of separating the maximum amount of platinum and palladium from catalysts and changing them into usable forms. The petroleum and petrochemical units use Pt and Pd catalyst for reactions such as reforming and hydrogenation. Because these materials contain valuable metals, such as Pt and Pd, these metals should be recycled. Based on economic reasons and the high price of new catalysts, petrochemical companies should solve this problem. The new method in this work may help to recover these metals from spent catalyst. This method may help solve several environmental problems. In this work, the recovery of platinum and palladium from petroleum catalysts has been studied using spent catalysts. Two catalysts were characterized by XRF, XRD, and AAS. Aqua regia, used as a leaching agent, and the effect of dissolution temperature and time, Liquid/Solid (L/S) ratio, size of particles, and elimination of coke were also investigated. Under optimized conditions, the leaching process was done with 98% efficiency. Recovery of platinum and palladium from the leached solutions was done by the adsorption process with Activated Carbon (AC) in an environmentally friendly manner. According to the results, the optimum operating conditions for platinum and palladium removal by activated carbon were a temperature of a solution of 85 and 98℃, pH = 0.5 and 2, time of adsorption 180 and 150 min and adsorbent loading capacity = 18.75 mgPt/gAC and 12.5 mgPd/gAC, respectively. The activated carbon containing platinum and palladium was decomposed by ignition to produce platinum and palladium powder with commercial purity of 96.5% and 96.3% respectively.

Performance Comparison of High Temperature Pt-Based Sensor Using Pt Core-Shell Powder and Paste

Abstract Platinum core-shell powder materials are compared and discussed in an oxygen sensor application. The conductive layer materials are prepared by chemical precipitation in the absence or presence of substrate powders, such as YSZ or alumina, to produce platinum powders or platinum/ceramic core/shell composites, respectively. Physical and bulk powder characteristics are presented and discussed. An oxygen sensor is constructed and overall performance is presented to compare the different conductive materials using HTCC tapes and pre-fired substrates.

Extraction and Stripping of Platinum from Hydrochloric Acid Medium by Mixed Imidazolium Ionic Liquids

Hydrophilic ionic liquids, 1-alkyl-3-methylimidazolium chloride ([Cnmim]Cl, n = 12, 14, and 16) are tested to precipitate Pt(IV) from hydrochloric acid medium. Meanwhile the Pt(IV) extractions are performed with hydrophobic ionic liquids, including 1-alkyl-3-methylimidazolium hexafluorophosphate ([Cnmim]PF6, n = 4, 6, and 8) and 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C8mim]NTf2). Based on Job’s method, infrared spectra, and 1H NMR analysis, the anion-exchange mechanism is confirmed during the Pt(IV) precipitation. The mixed hydrophilic–hydrophobic ionic liquids ([Cnmim]Cl/[C8mim]PF6) are developed for Pt(IV) extraction, which significantly increase the Pt(IV) extractability compared to the single hydrophobic ionic liquid. Under the optimum conditions, the [C16mim]Cl/[C8mim]PF6 system shows high extractability as well as outstanding selectivity for Pt(IV) over the base metals (Mn(II), Cu(II), Co(II), Ni(II), Fe(III), and Al(III)). By reductive stripping, Pt(IV) in the organic phase can be stripped in the form of platinum powders using hydrazine hydrate; at the same time [C16mim]Cl is regenerated in the organic phase. The mixed [C16mim]Cl/[C8mim]PF6 ionic liquids can be reused to extract Pt(IV). Therefore, the method is highly effective, selective, and recyclable to extract Pt(IV) and recover metal platinum.

Thermostimulated transformations of highly disperse powders of platinum group metals in an argon atmosphere

The behavior of palladium, rhodium, iridium, and platinum powders during their heating in an argon atmosphere was studied by differential scanning calorimetry (DSC). The DSC curves showed the exothermal peaks corresponding to the enlargement of the platinum group metal powders under study. Electron microscopy and XRD studies revealed that the particle size of highly disperse powders changed during the heating. Chemisorbed oxygen was removed from the powder surface above 800 K. During the heating of the mechanical mixture of highly disperse platinum and palladium powders, a solid solution formed with an exothermal effect.

Mechanical alloying of platinum with 5% ZrO2 nanoparticles for glass making tools

Synthesis and characterization of mechanically alloyed Pt–5%ZrO2 (volume fraction) for structural components in the glass industry were described. Zirconia (ZrO2) nanoparticles (<100 nm) were produced by the electrical explosion of zirconium (Zr) wires, and blended with platinum (Pt) powders (<44 μm) for 2–72 h in ambient atmosphere. The Pt particle size followed the typical decreasing trend of the normal ball milling process up to 48 h, but particle agglomeration was observed at 72 h. The grain size evolution was similar to that of the particle size, dropping down to around 50 nm at 48 h. The root mean square strain of the Pt crystallites showed the opposite behavior, maximizing at 48 h with a subsequent relaxation process. For the 48 h ball milled powders, spark plasma sintering was carried out to form a bulk disk. The measured mass loss of the sintered bulk sample shows a decent thermal stability despite its relatively low density.