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Dry synthesis of brannerite (UTi2O6) by mechanochemical treatment

  • Daisuke Akiyama EMAIL logo , Tomoki Mishima , Yoshihiro Okamoto and Akira Kirishima
Published/Copyright: April 27, 2023
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High Temperature Materials and Processes
From the journal High Temperature Materials and Processes Volume 42 Issue 1

Abstract

A powder mixture of UO2 and TiO2 was mechanochemically treated in a planetary ball mill under Ar atmosphere for 1 h using a tungsten carbide vial and balls as the milling medium. Such mechanochemical (MC) treatment reduced the crystallinity of UO2 and TiO2. The mechanochemically treated powder mixture was heated at 700–1,300°C for 6 h under Ar atmosphere and analyzed by X-ray diffraction analysis, scanning electron microscopy-energy-dispersive X-ray spectroscopy, and X-ray absorption fine structure analysis. For comparison, a UO2 and TiO2 mixture without MC treatment was heated and analyzed under the same conditions. UTi2O6 did not form below 1,100°C without MC treatment and only the starting materials were observed. At 1,200 and 1,300°C, a small amount of UTi2O6 and equal amounts of UTi2O6 and UO2 were formed, respectively. The mechanochemically treated sample produced nearly pure UTi2O6 containing small amounts of UO2 impurities when heated above 900°C for 6 h. UTi2O6 was highly crystalline and uniform regardless of the synthesis temperature. It is suggested that the crystallinity of UO2 and TiO2 was reduced and the formation of UTi2O6 was promoted by MC treatment.

Keywords: brannerite; uranium titanate; mechanochemical method; dry synthesis

1 Introduction

Brannerite, UTi2O6, is a U ore in U deposits. UTi2O6 is present in several geological environments such as Elliot Lake (Ontario, Canada) [1,2], Mount Isa (Australia) [3,4], Kirovograd (Ukraine), Crocker Well (Australia) [5], and Domes Region (Zambia) [6] and in some U deposits in the Witwatersrand area (South Africa) [7]. It is commonly produced as an amorphous mineral owing to radiation damage from the alpha decay of U, Th, and their daughter isotopes. It can be recrystallized by heating at approximately 1,000°C [8,9].

UTi2O6 is chemically durable and can form solid solutions with alkaline earth elements, rare earth elements, and actinides like Pu and Th. It is a minor phase in titanate-based and pyrochlore-rich Synroc-type ceramics designed for the geological immobilization of excess Pu from nuclear weapons [10]. It was determined that UTi2O6 in ceramics incorporates Pu and neutron absorbers like Gd and Hf [11]. Neutron absorbers can overcome potential criticality problems associated with Pu.

Many researchers have reported on the chemical durability and synthesis of UTi2O6. The chemical durability of UTi2O6 is lower than those of other compounds that form in Synroc, such as pyrochlore and zirconolite, but is higher than that of borosilicate glass which is used for the solidification of high-level radioactive waste solutions [12,13,14]. The chemical durability of naturally occurring amorphous UTi2O6 is approximately 1/10 that of synthesized crystalline UTi2O6. However, it is more chemically durable than borosilicate glass used for the solidification of high-level radioactive waste solutions [9].

The synthesis of UTi2O6 requires two steps: pretreatment, which involves mixing U and Ti compounds, and heat treatment, which involves the calcination of the mixture. Two types of reported pretreatment processes for the synthesis of UTi2O6 are commonly used, viz. dry and wet pretreatments. Dry pretreatment is a simple process that involves mixing and pelleting U and Ti. Wet pretreatment is a complex process in which U and Ti are dissolved, dried, or coprecipitated. The resulting mixture is then calcined and pelletized. The details of the pretreatment processes are provided below.

Dry pretreatment:

  1. UO2 and TiO2 (anatase) powders were mixed in a ball mill and pelletized [15].

    Wet pretreatment:

  2. Uranyl acetate and titanyl sulfate were dissolved in an oxalic acid solution, dried by heating at 200 and 600°C in air and a reducing atmosphere, respectively, and pelletized [16,17].

  3. Uranyl nitrate and titanium alkoxide were dissolved in water and heated at 200 and 750°C in air. The mixture was then wet-mixed for 16 h and pelletized [18,19].

  4. Uranyl nitrate or uranyl acetate and titanyl sulfate were dissolved in 1 M oxalic acid and stirred. A concentrated ammonium hydroxide solution was added to raise the pH to 10–11, and the coprecipitation of titanyl hydroxide and uranyl hydroxide occurred. The precipitate was washed twice with an ammonium hydroxide solution at pH 11 and dried at 100°C. After drying, the mixture was calcined at 600°C in air for 5 h [16].

After dry pretreatment, UTi2O6 was synthesized by heating at 1,350°C for 300 h in a mixture of 5% CO and 95% CO2. UTi2O6 synthesized using this method contained 0.6 at% unreacted UO2 [15]. After wet pretreatment, UTi2O6 was synthesized by heating at 1,100–1,300°C for 5–96 h or more in an inert or reducing atmosphere. Hussein et al. reported the formation of UTi2O6 by heating at 900°C for 5 h in an Ar and 5% H2 atmosphere, but unreacted UO2 and TiO2 was present in the final product. Temperatures exceeding 1,100°C were required to synthesize pure UTi2O6 [16]. Wet pretreatment can accelerate the reaction rate and lower the synthesis temperature compared with dry pretreatment. However, wet pretreatment is disadvantageous as a solidification process for radioactive waste because of its complicated operation and the generation of radioactive liquid waste. Furthermore, because U in solution is hexavalent, it is necessary to use reductants (such as H2 gas) during heat treatment to synthesize UTi2O6, which is composed of tetravalent U. Alternatively, dry pretreatment is a simple process that does not generate radioactive liquid waste or require a reductant (H2 gas). However, dry pretreatment requires an extended reaction time and higher reaction temperature compared with wet pretreatment.

In this study, we aimed to reduce the heating time and temperature for the synthesis of UTi2O6 by dry pretreatment using mechanochemical (MC) treatment. Dry MC treatment uses a planetary ball mill to improve the reactivity by rotating a hard ball and raw powder in a cylindrical container that applies mechanical energy. UO2 and TiO2 (rutile) powders were MC treated at a molar ratio of U:Ti = 1:2 and pelletized. The pellets were heated at 700–1300°C for 6 h in an Ar atmosphere to investigate the formation temperature of UTi2O6. To confirm the effect of MC treatment, UO2 and TiO2 pellets without MC treatment were heat-treated under the same conditions as when MC treatment was applied. After MC treatment, the crystal structures of the synthesized UTi2O6 were analyzed by X-ray diffraction (XRD) analysis, scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX), and X-ray absorption fine structure (XAFS) analysis to determine the reaction mechanism.

2 Materials and methods

2.1 Materials

UO2 was prepared by reducing U3O8 at 1,000°C for 4 h in an Ar and 10% H2 atmosphere at a gas flow rate of 60 mL·min−1. Rutile TiO2 powder (99% purity) was a special grade reagent obtained from FUJIFILM Wako Pure Chemical Corporation.

2.2 Synthesis

2.2.1 Mechanochemical treatment

A planetary ball mill (Fritsch Pulverisette-7) was used to mill UO2 and TiO2 powders. A tungsten carbide pot (inner volume: 45 mL) was loaded with 0.8 g of the powder mixture and 10 tungsten carbide balls (φ10 mm). The milling pot was transferred to an acrylicvacuum glove box. The glove box was evacuated and refilled with Ar (G1 grade, 99.9999%) three times to make the internal atmosphere inert. The milling pot and its lid were packed with silicone rubber before being removed from the glove box. The boundary between the milling pot and lid was sealed with aluminum tape to maintain an inert atmosphere. After setting a pair of milling pots in a planetary mill, the mill was rotated at 700 rpm at room temperature. The milling operation was interrupted every 5 min for 1 h to avoid overheating owing to MC treatment; hence, the total milling time was 30 min. Finally, the pot was left to cool for approximately 30 min and the mixed sample was removed from the pot.

Without MC treatment, UO2 and TiO2 powders were mixed in a mortar.

2.2.2 Heat treatment

The MC-treated mixture was pelletized (φ7 mm) and placed on an alumina boat. The sample was sintered under an Ar (G1 grade, 99.9999%) atmosphere at 700–1,300°C for 6 h. For comparison, mixtures without MC treatment were heated using the same procedure as when MC treatment was applied.

2.3 XRD

XRD patterns were obtained using an X-ray diffractometer (Rigaku Mini Flex 600) with Ni-filtered Cu Kα radiation operated at 40 kV and 15 mA. Diffraction patterns were collected in the 2θ range of 10–140° with a step interval of 0.02° at a scan rate of 5°·min−1.

2.4 SEM-EDX

A Hitachi VP-SEM SU1510 by Hitachi High Technologies Corporation was used to perform SEM. EDS was carried out using an EMAX EX-250, X-act by Oxford Instruments.

2.5 XAFS

XAFS measurements were performed at the BL-27B station of the Photon Factory in KEK, Tsukuba, Japan. An X-ray beam monochromatized by Si (111) double crystals is available at the beamline [20]. XAFS spectra of the U L3-edge (E 0 = 17.166 keV) with energies of 16.865–17.874 keV were collected using this transmission method, while those of a Ti K-edge (E 0 = 4.966 keV) with energies of 4.780–5.856 keV were obtained using a fluorescence method. X-ray energy was calibrated using the standard oxides UO2 and U3O8 for the U L3-edge and TiO2 for the Ti K-edge. XAFS data were analyzed using WinXAS ver. 3.2 software [21] to obtain the extended XAFS (EXAFS) k 3 function (k) and the Fourier transform magnitude (|FT|). Structural parameters such as the coordination number and interatomic distance were obtained using the curve-fitting procedure in WinXAS. The correction parameters required in the fitting analysis, namely the phase shift and backscattering amplitude, were obtained from the XAFS simulation software FEFF Ver. 8.4.

3 Results and discussion

3.1 Mechanochemical treatment

Figure 1 shows the XRD patterns of the UO2 and TiO2 mixture before and after MC treatment. XRD measurements were performed on UO2 and TiO2 to determine the peaks present before MC treatment. A broadening of the UO2 and TiO2 peaks was noted after MC treatment. This suggests that the crystallinity of UO2 and TiO2 decreased. The lattice constant of UO2 changed from 5.471 to 5.462 Å after MC treatment. The minimal oxidation of UO2 may be caused by the small amount of remaining oxygen in the milling pot. No UTi2O6 peaks were observed after MC treatment.

Figure 1 X-ray diffraction patterns of UO2 and TiO2 mixtures before and after MC treatment.
Figure 1

X-ray diffraction patterns of UO2 and TiO2 mixtures before and after MC treatment.

Figure S1 shows that the mixture of UO2 and TiO2 before MC treatment has separate distributions of UO2 and TiO2 of a few microns. As shown in Figure 2(a), the particle size in the mixture after MC treatment was less than a few microns. From Figure 2(b) and (c), it can be observed that U and Ti are similarly distributed. It was concluded that MC treatment reduced the crystallinity of UO2 and TiO2 and that they became a homogeneous mixture consisting of fine particles.

Figure 2 SEM-EDX of UO2 and TiO2 mixtures after MC treatment. (a) Scanning electron microscopy image (BSE, ×8,000), (b) U distribution, and (c) Ti distribution of a UO2 and TiO2 mixture.
Figure 2

SEM-EDX of UO2 and TiO2 mixtures after MC treatment. (a) Scanning electron microscopy image (BSE, ×8,000), (b) U distribution, and (c) Ti distribution of a UO2 and TiO2 mixture.

3.2 Heat treatment of the mixture

3.2.1 UTi2O6 synthesis without MC treatment

A UO2 and TiO2 mixture that was not MC treated was heated. Figure 3 shows XRD measurements of samples heated at 1,000–1,300°C. Below 1,100°C, only the UO2 and TiO2 peaks of the starting materials were observed and no UTi2O6 peaks were present. At 1,200°C, the main phases were UO2 and TiO2, whereas the UTi2O6 phase was observed as a minor phase with small XRD peak intensities. At 1,300°C, similar amounts of UTi2O6 phase and unreacted UO2 and TiO2 phases were observed. Rietveld analysis was used to quantitatively analyze the XRD pattern of the sample heated at 1,300°C. The abundances of the UO2 and UTi2O6 phases were 59 ± 1 and 41 ± 2 at%, respectively. UTi2O6 formed without MC treatment at 1,300°C, but the heating time needed to be prolonged to obtain pure UTi2O6.

Figure 3 X-ray diffraction patterns of a UO2 and TiO2 mixture without MC treatment after being heated.
Figure 3

X-ray diffraction patterns of a UO2 and TiO2 mixture without MC treatment after being heated.

3.2.2 UTi2O6 synthesis with MC treatment

After MC treatment, the UO2 and TiO2 mixture was heated. Figure 4 shows XRD patterns of samples heated at 700–1,300°C. Below 800°C, only the UO2 and TiO2 peaks of the starting materials were observed and no UTi2O6 was formed. At 900°C, the UTi2O6 phase coexisted with approximately 22 at% UO2. Above 1,000°C, nearly pure UTi2O6 phase was formed with less than 11 at% coexistence of UO2. The lattice parameters of the formed UTi2O6 are listed in Table 1. From Table 1, it was confirmed that the lattice parameters remained consistent. This suggests that a comparable UTi2O6 phase was formed regardless of the heating temperature.

Figure 4 X-ray diffraction patterns of a UO2 and TiO2 mixture with MC treatment after being heated.
Figure 4

X-ray diffraction patterns of a UO2 and TiO2 mixture with MC treatment after being heated.

Table 1

Lattice parameters of the synthesized UTi2O6 and remaining UO2 after heat with MC treatment

Heating temperature (°C) Lattice parameter of UTi2O6 Remaining UO2 (at%)
a (Å) b (Å) c (Å)
900 9.820 ± 0.007 3.7700 ± 0.0010 6.926 ± 0.005 22.0 ± 3.7
1,000 9.813 ± 0.004 3.7722 ± 0.0017 6.927 ± 0.003 11.1 ± 1.8
1,100 9.825 ± 0.004 3.7745 ± 0.0018 6.935 ± 0.003 3.0 ± 0.6
1,200 9.824 ± 0.003 3.7728 ± 0.0012 6.931 ± 0.002 8.9 ± 1.2
1,300 9.817 ± 0.002 3.7686 ± 0.0009 6.923 ± 0.002 5.8 ± 0.4

Figure 5 shows the SEM-EDS analysis of UTi2O6 synthesized by heat treatment at 1,100°C. Figure 5(a) indicates that the particle size of the mixture remained consistent at less than a few microns before and after heat treatment. Figure 5(b) and (c) shows that U and Ti were similarly distributed before and after heating.

Figure 5 SEM-EDX analysis after MC treatment of a UO2 and TiO2 mixture at 1,100°C. (a) Scanning electron microscopy image (BSE, ×8,000), (b) U distribution, and (c) Ti distribution of a UO2 and TiO2 mixture.
Figure 5

SEM-EDX analysis after MC treatment of a UO2 and TiO2 mixture at 1,100°C. (a) Scanning electron microscopy image (BSE, ×8,000), (b) U distribution, and (c) Ti distribution of a UO2 and TiO2 mixture.

3.3 XAFS analysis

Figure 6 shows U L3 X-ray absorption near the edge structure (XANES) spectra of UO2, U3O8, a UO2 and TiO2 mixture that was MC treated without heating and UTi2O6 synthesized at 1,300°C with MC treatment. Based on Figure 6, it was deduced that the U in the MC-treated UO2 and TiO2 mixture and synthesized UTi2O6 were tetravalent because their white-line energies were similar to that of UO2, which is the standard material of tetravalent U. The XANES spectra of UO2 and the UO2 and TiO2 mixture were very similar, which indicated that the crystal structure of UO2 was maintained after MC treatment. The XAFS spectra of UTi2O6 and UO2 indicated that alternative crystals to UO2 formed in the synthesized UTi2O6 that was MC treated.

Figure 6 U L3-edge X-ray absorption near the edge structure spectra of UO2, U3O8, a UO2 and TiO2 mixture with MC treatment, and UTi2O6 synthesized at 1,300°C.
Figure 6

U L3-edge X-ray absorption near the edge structure spectra of UO2, U3O8, a UO2 and TiO2 mixture with MC treatment, and UTi2O6 synthesized at 1,300°C.

Figure 7 shows EXAFS and FT magnitude functions of the U L3- and Ti K-edges of UO2, the MC-treated UO2 and TiO2 mixture, and UTi2O6 synthesized at 900 and 1,300°C. The U L3 EXAFS function in Figure 7(a-1) shows that the spectrum of UO2 did not change significantly after MC treatment. This indicates that the crystal structure of UO2 remained consistent. There is a considerable difference between the spectra of UTi2O6 and UO2. The U L3-edge FT magnitude function in Figure 7(a-2) shows that the U–O and U–U bond distances in the first and second coordination spheres remained unchanged after UO2 was MC treated. However, the peak intensity corresponding to U–U decreased. This suggests that the crystallinity of UO2 has decreased. The U–O distances of UTi2O6 and UO2 are the same. However, the peak corresponding to the U–U distance in the UTi2O6 spectrum disappeared. Structural parameters, such as the coordination number and interatomic distance, were calculated through the curve-fitting analysis of the FT function (Table 2). The U–O distance and coordination number in UO2 remained unchanged after MC treatment. The increased Debye–Waller factor value indicated that MC treatment caused the crystallinity to decrease. The U–O bond lengths in UTi2O6 are (1) two-coordinated U–O1 = 2.252 ± 0.002, (2) four-coordinated U–O2 = 2.296 ± 0.001, and (3) two-coordinated U–O3 = 2.824 ± 0.002 Å [22] (Figure S2). Curve-fitting analysis was performed for two-component systems with short-distance U–O bonds (six-coordination) for (1) and (2), and long-distance U–O bonds (two-coordination) for (3). The results of the analysis are shown in Table 2. The local structure of UTi2O6 is consistent with reported U–O bond distances and coordination numbers. There were no significant changes to the local structure of U in UTi2O6 synthesized at 900 and 1,300°C.

Figure 7 (1) EXAFS and (2) FT magnitude functions of the (a) U L3- and (b) Ti K-edges of UO2, TiO2, a UO2, and TiO2 mixture with MC treatment, and UTi2O6 synthesized at 900 and 1,300°C.
Figure 7

(1) EXAFS and (2) FT magnitude functions of the (a) U L3- and (b) Ti K-edges of UO2, TiO2, a UO2, and TiO2 mixture with MC treatment, and UTi2O6 synthesized at 900 and 1,300°C.

Table 2

Structural parameters: coordination number N, interionic distance r (U–O), Debye–Waller factor σ 2 in UO2, UO2 and TiO2 mixture with MC treatment, and UTi2O6 synthesized at 900 and 1,300°C by U L3-edge XAFS

Sample S0 2 N r U–O (Å) σ 2 (Å2)
UO2 0.95 8.2 2.343 0.00663
UO2 and TiO2 (MC) 0.95 8.1 2.321 0.01120
UTi2O6 (900°C) 0.95 5.9 2.277 0.00639
2.0 2.832 0.00950
UTi2O6 (1,300°C) 0.95 6.0 2.266 0.00452
2.0 2.815 0.00879

Similar to UO2, the Ti K EXAFS function in Figure 7(a-2) indicated that the TiO2 spectrum did not change significantly after MC treatment. However, the amplitude of the spectra slightly decreased. This suggests that the crystallinity of TiO2 decreased. The spectra of UTi2O6 were significantly different from those of TiO2 after MC treatment. The Ti K-edge FT magnitude function in Figure 7 shows that the bond distances of Ti-O and Ti-Ti in the first and second coordination spheres remained unchanged after TiO2 was MC treated. However, the peak intensity corresponding to Ti-Ti decreased. This suggests that MC treatment caused the crystallinity of TiO2 to decrease. The Ti-Ti peak observed in TiO2 disappeared in UTi2O6.

3.4 Evaluation of the crystal structures in the UTi2O6 synthesis process

XRD results showed that the crystal structures of UO2 and TiO2 were maintained when a UO2 and TiO2 mixture was MC treated, but the relative intensity of the peaks decreased and broadened. The SEM-EDX results show that MC treatment of mixed samples of UO2 and TiO2 resulted in a similar distribution of U and Ti. These results indicate that MC treatment of the UO2 and TiO2 mixture reduces the crystallinity of UO2 and TiO2. However, no chemical reactions occur and U and Ti exists as separate phases. The results in Table 1 and Figure 7 confirm that the lattice parameter and local structures of U and Ti in UTi2O6 remains unchanged regardless of the heating temperature. This reveals that high crystalline UTi2O6 can be synthesized by MC pretreatment and heat treatment at 900°C. The reaction temperature (900°C) is similar to that required for recrystallization of naturally existing amorphous UTi2O6 (900°C). The formation temperature of UTi2O6 exceeded 1,200°C without MC treatment and the formation rate of UTi2O6 was faster with MC treatment. The faster reaction rates of UO2 and TiO2 with MC treatment are potentially caused by increasing contact points between UO2 and TiO2. The contact points increased because the UO2 and TiO2 particles are finer and more uniformly mixed and their surfaces are more activated. The lower formation temperature of UTi2O6 may be attributed to the lower activation energy of UTi2O6 formation owing to the lower crystallinity of UO2 and TiO2. Approximately 22 at% of UO2 remained as impurities when the UO2 and TiO2 mixture was heat-treated at 900°C, and less than 11 at% of UO2 remained at 1,000°C or higher. It is assumed that the formation reaction did not go to completion in the case of heat treatment at 900°C for 6 h. The surface of UO2 particles was partially oxidized by MC treatment, which prevented the formation of UIVTi2O6. Hence, approximately 11 at% of UO2 remained after heat treatment at 1,000°C or higher, regardless of the reaction temperature.

4 Conclusions

MC treatment of a powder mixture of UO2 and TiO2 reduced their crystallinity. UTi2O6 with 22 at% and <11 at% impurities were synthesized from this mixture in an Ar atmosphere by heat treatment at 900 and >1,000°C, respectively, for 6 h. The synthesized UTi2O6 crystals had consistent crystal structures, regardless of the synthesis temperature (900–1,300°C). Compared with the previously reported dry process that required a reaction temperature of 1,350°C for 300 h, the proposed process of UTi2O6 synthesis via MC treatment significantly lowered the synthesis temperature by 450°C and shortened the synthesis time by 294 h. However, small amounts of UO2 impurities remained in the final product. In conclusion, MC treatment enabled the synthesis of nearly pure UTi2O6 at considerably lower temperatures, shorter reaction times, and without reductants compared to previously reported synthesis methods.

Acknowledgments

This study was supported by JSPS KAKENHI (Grant Numbers JP17K14908 and JP20K15203). A part of this study was also supported by the “Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials” of the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT). This work was approved by the Photon Factory Program Advisory Committee (proposal number 2021G656). We would like to thank Editage (www.editage.com) for English language editing.

  1. Funding information: JSPS KAKENHI (Grant Numbers JP17K14908 and JP20K15203) and “Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials” of the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT).

  2. Author contributions: Daisuke Akiyama: conceptualization, methodology, writing – original draft, writing – review and editing, sample synthesis; Tomoki Mishima: sample synthesis, XRD analysis, SEM-EDX analysis, data curation; Yoshihiro Okamoto: XAFS experiment, data curation; and Akira Kirishima: conceptualization, writing – original draft.

  3. Conflict of interest: The authors state no conflict of interest.

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Received: 2022-07-27
Revised: 2023-01-06
Accepted: 2023-01-06
Published Online: 2023-04-27

© 2023 the author(s), published by De Gruyter

This work is licensed under the Creative Commons Attribution 4.0 International License.

Articles in the same Issue

  1. Research Articles
  2. First-principles investigation of phase stability and elastic properties of Laves phase TaCr2 by ruthenium alloying
  3. Improvement and prediction on high temperature melting characteristics of coal ash
  4. First-principles calculations to investigate the thermal response of the ZrC(1−x)Nx ceramics at extreme conditions
  5. Study on the cladding path during the solidification process of multi-layer cladding of large steel ingots
  6. Thermodynamic analysis of vanadium distribution behavior in blast furnaces and basic oxygen furnaces
  7. Comparison of data-driven prediction methods for comprehensive coke ratio of blast furnace
  8. Effect of different isothermal times on the microstructure and mechanical properties of high-strength rebar
  9. Analysis of the evolution law of oxide inclusions in U75V heavy rail steel during the LF–RH refining process
  10. Simultaneous extraction of uranium and niobium from a low-grade natural betafite ore
  11. Transfer and transformation mechanism of chromium in stainless steel slag in pedosphere
  12. Effect of tool traverse speed on joint line remnant and mechanical properties of friction stir welded 2195-T8 Al–Li alloy joints
  13. Technology and analysis of 08Cr9W3Co3VNbCuBN steel large diameter thick wall pipe welding process
  14. Influence of shielding gas on machining and wear aspects of AISI 310–AISI 2205 dissimilar stainless steel joints
  15. Effect of post-weld heat treatment on 6156 aluminum alloy joint formed by electron beam welding
  16. Ash melting behavior and mechanism of high-calcium bituminous coal in the process of blast furnace pulverized coal injection
  17. Effect of high temperature tempering on the phase composition and structure of steelmaking slag
  18. Numerical simulation of shrinkage porosity defect in billet continuous casting
  19. Influence of submerged entry nozzle on funnel mold surface velocity
  20. Effect of cold-rolling deformation and rare earth yttrium on microstructure and texture of oriented silicon steel
  21. Investigation of microstructure, machinability, and mechanical properties of new-generation hybrid lead-free brass alloys
  22. Soft sensor method of multimode BOF steelmaking endpoint carbon content and temperature based on vMF-WSAE dynamic deep learning
  23. Mechanical properties and nugget evolution in resistance spot welding of Zn–Al–Mg galvanized DC51D steel
  24. Research on the behaviour and mechanism of void welding based on multiple scales
  25. Preparation of CaO–SiO2–Al2O3 inorganic fibers from melting-separated red mud
  26. Study on diffusion kinetics of chromium and nickel electrochemical co-deposition in a NaCl–KCl–NaF–Cr2O3–NiO molten salt
  27. Enhancing the efficiency of polytetrafluoroethylene-modified silica hydrosols coated solar panels by using artificial neural network and response surface methodology
  28. High-temperature corrosion behaviours of nickel–iron-based alloys with different molybdenum and tungsten contents in a coal ash/flue gas environment
  29. Characteristics and purification of Himalayan salt by high temperature melting
  30. Temperature uniformity optimization with power-frequency coordinated variation in multi-source microwave based on sequential quadratic programming
  31. A novel method for CO2 injection direct smelting vanadium steel: Dephosphorization and vanadium retention
  32. A study of the void surface healing mechanism in 316LN steel
  33. Effect of chemical composition and heat treatment on intergranular corrosion and strength of AlMgSiCu alloys
  34. Soft sensor method for endpoint carbon content and temperature of BOF based on multi-cluster dynamic adaptive selection ensemble learning
  35. Evaluating thermal properties and activation energy of phthalonitrile using sulfur-containing curing agents
  36. Investigation of the liquidus temperature calculation method for medium manganese steel
  37. High-temperature corrosion model of Incoloy 800H alloy connected with Ni-201 in MgCl2–KCl heat transfer fluid
  38. Investigation of the microstructure and mechanical properties of Mg–Al–Zn alloy joints formed by different laser welding processes
  39. Effect of refining slag compositions on its melting property and desulphurization
  40. Effect of P and Ti on the agglomeration behavior of Al2O3 inclusions in Fe–P–Ti alloys
  41. Cation-doping effects on the conductivities of the mayenite Ca12Al14O33
  42. Modification of Al2O3 inclusions in SWRH82B steel by La/Y rare-earth element treatment
  43. Possibility of metallic cobalt formation in the oxide scale during high-temperature oxidation of Co-27Cr-6Mo alloy in air
  44. Multi-source microwave heating temperature uniformity study based on adaptive dynamic programming
  45. Round-robin measurement of surface tension of high-temperature liquid platinum free of oxygen adsorption by oscillating droplet method using levitation techniques
  46. High-temperature production of AlN in Mg alloys with ammonia gas
  47. Review Article
  48. Advances in ultrasonic welding of lightweight alloys: A review
  49. Topical Issue on High-temperature Phase Change Materials for Energy Storage
  50. Compositional and thermophysical study of Al–Si- and Zn–Al–Mg-based eutectic alloys for latent heat storage
  51. Corrosion behavior of a Co−Cr−Mo−Si alloy in pure Al and Al−Si melt
  52. Al–Si–Fe alloy-based phase change material for high-temperature thermal energy storage
  53. Density and surface tension measurements of molten Al–Si based alloys
  54. Graphite crucible interaction with Fe–Si–B phase change material in pilot-scale experiments
  55. Topical Issue on Nuclear Energy Application Materials
  56. Dry synthesis of brannerite (UTi2O6) by mechanochemical treatment
  57. Special Issue on Polymer and Composite Materials (PCM) and Graphene and Novel Nanomaterials - Part I
  58. Heat management of LED-based Cu2O deposits on the optimal structure of heat sink
  59. Special Issue on Recent Developments in 3D Printed Carbon Materials - Part I
  60. Porous metal foam flow field and heat evaluation in PEMFC: A review
  61. Special Issue on Advancements in Solar Energy Technologies and Systems
  62. Research on electric energy measurement system based on intelligent sensor data in artificial intelligence environment
  63. Study of photovoltaic integrated prefabricated components for assembled buildings based on sensing technology supported by solar energy
  64. Topical Issue on Focus of Hot Deformation of Metaland High Entropy Alloys - Part I
  65. Performance optimization and investigation of metal-cored filler wires for high-strength steel during gas metal arc welding
  66. Three-dimensional transient heat transfer analysis of micro-plasma arc welding process using volumetric heat source models
https://doi.org/10.1515/htmp-2022-0268
Keywords for this article
brannerite; uranium titanate; mechanochemical method; dry synthesis
Creative Commons
BY 4.0

Articles in the same Issue

  1. Research Articles
  2. First-principles investigation of phase stability and elastic properties of Laves phase TaCr2 by ruthenium alloying
  3. Improvement and prediction on high temperature melting characteristics of coal ash
  4. First-principles calculations to investigate the thermal response of the ZrC(1−x)Nx ceramics at extreme conditions
  5. Study on the cladding path during the solidification process of multi-layer cladding of large steel ingots
  6. Thermodynamic analysis of vanadium distribution behavior in blast furnaces and basic oxygen furnaces
  7. Comparison of data-driven prediction methods for comprehensive coke ratio of blast furnace
  8. Effect of different isothermal times on the microstructure and mechanical properties of high-strength rebar
  9. Analysis of the evolution law of oxide inclusions in U75V heavy rail steel during the LF–RH refining process
  10. Simultaneous extraction of uranium and niobium from a low-grade natural betafite ore
  11. Transfer and transformation mechanism of chromium in stainless steel slag in pedosphere
  12. Effect of tool traverse speed on joint line remnant and mechanical properties of friction stir welded 2195-T8 Al–Li alloy joints
  13. Technology and analysis of 08Cr9W3Co3VNbCuBN steel large diameter thick wall pipe welding process
  14. Influence of shielding gas on machining and wear aspects of AISI 310–AISI 2205 dissimilar stainless steel joints
  15. Effect of post-weld heat treatment on 6156 aluminum alloy joint formed by electron beam welding
  16. Ash melting behavior and mechanism of high-calcium bituminous coal in the process of blast furnace pulverized coal injection
  17. Effect of high temperature tempering on the phase composition and structure of steelmaking slag
  18. Numerical simulation of shrinkage porosity defect in billet continuous casting
  19. Influence of submerged entry nozzle on funnel mold surface velocity
  20. Effect of cold-rolling deformation and rare earth yttrium on microstructure and texture of oriented silicon steel
  21. Investigation of microstructure, machinability, and mechanical properties of new-generation hybrid lead-free brass alloys
  22. Soft sensor method of multimode BOF steelmaking endpoint carbon content and temperature based on vMF-WSAE dynamic deep learning
  23. Mechanical properties and nugget evolution in resistance spot welding of Zn–Al–Mg galvanized DC51D steel
  24. Research on the behaviour and mechanism of void welding based on multiple scales
  25. Preparation of CaO–SiO2–Al2O3 inorganic fibers from melting-separated red mud
  26. Study on diffusion kinetics of chromium and nickel electrochemical co-deposition in a NaCl–KCl–NaF–Cr2O3–NiO molten salt
  27. Enhancing the efficiency of polytetrafluoroethylene-modified silica hydrosols coated solar panels by using artificial neural network and response surface methodology
  28. High-temperature corrosion behaviours of nickel–iron-based alloys with different molybdenum and tungsten contents in a coal ash/flue gas environment
  29. Characteristics and purification of Himalayan salt by high temperature melting
  30. Temperature uniformity optimization with power-frequency coordinated variation in multi-source microwave based on sequential quadratic programming
  31. A novel method for CO2 injection direct smelting vanadium steel: Dephosphorization and vanadium retention
  32. A study of the void surface healing mechanism in 316LN steel
  33. Effect of chemical composition and heat treatment on intergranular corrosion and strength of AlMgSiCu alloys
  34. Soft sensor method for endpoint carbon content and temperature of BOF based on multi-cluster dynamic adaptive selection ensemble learning
  35. Evaluating thermal properties and activation energy of phthalonitrile using sulfur-containing curing agents
  36. Investigation of the liquidus temperature calculation method for medium manganese steel
  37. High-temperature corrosion model of Incoloy 800H alloy connected with Ni-201 in MgCl2–KCl heat transfer fluid
  38. Investigation of the microstructure and mechanical properties of Mg–Al–Zn alloy joints formed by different laser welding processes
  39. Effect of refining slag compositions on its melting property and desulphurization
  40. Effect of P and Ti on the agglomeration behavior of Al2O3 inclusions in Fe–P–Ti alloys
  41. Cation-doping effects on the conductivities of the mayenite Ca12Al14O33
  42. Modification of Al2O3 inclusions in SWRH82B steel by La/Y rare-earth element treatment
  43. Possibility of metallic cobalt formation in the oxide scale during high-temperature oxidation of Co-27Cr-6Mo alloy in air
  44. Multi-source microwave heating temperature uniformity study based on adaptive dynamic programming
  45. Round-robin measurement of surface tension of high-temperature liquid platinum free of oxygen adsorption by oscillating droplet method using levitation techniques
  46. High-temperature production of AlN in Mg alloys with ammonia gas
  47. Review Article
  48. Advances in ultrasonic welding of lightweight alloys: A review
  49. Topical Issue on High-temperature Phase Change Materials for Energy Storage
  50. Compositional and thermophysical study of Al–Si- and Zn–Al–Mg-based eutectic alloys for latent heat storage
  51. Corrosion behavior of a Co−Cr−Mo−Si alloy in pure Al and Al−Si melt
  52. Al–Si–Fe alloy-based phase change material for high-temperature thermal energy storage
  53. Density and surface tension measurements of molten Al–Si based alloys
  54. Graphite crucible interaction with Fe–Si–B phase change material in pilot-scale experiments
  55. Topical Issue on Nuclear Energy Application Materials
  56. Dry synthesis of brannerite (UTi2O6) by mechanochemical treatment
  57. Special Issue on Polymer and Composite Materials (PCM) and Graphene and Novel Nanomaterials - Part I
  58. Heat management of LED-based Cu2O deposits on the optimal structure of heat sink
  59. Special Issue on Recent Developments in 3D Printed Carbon Materials - Part I
  60. Porous metal foam flow field and heat evaluation in PEMFC: A review
  61. Special Issue on Advancements in Solar Energy Technologies and Systems
  62. Research on electric energy measurement system based on intelligent sensor data in artificial intelligence environment
  63. Study of photovoltaic integrated prefabricated components for assembled buildings based on sensing technology supported by solar energy
  64. Topical Issue on Focus of Hot Deformation of Metaland High Entropy Alloys - Part I
  65. Performance optimization and investigation of metal-cored filler wires for high-strength steel during gas metal arc welding
  66. Three-dimensional transient heat transfer analysis of micro-plasma arc welding process using volumetric heat source models
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