NiO reduction by Mg + C combined reducer at high heating rates

Zakaryan, Marieta K.; Nazaretyan, Khachik; Aydinyan, Sofiya; Kharatyan, S. L.

doi:10.1007/s10973-020-10148-5

Cited by 7 publications

(14 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In Table 1 the activation energy values obtained in this work and compared with similar thermite type mixtures obtained earlier [29,32,33]. It can be deduced that the influence of the heating rate is mainly notable on T s but not on the E a values.…”

Section: Calculation Of Activation Energymentioning

confidence: 55%

“…The interaction mechanism was primarily investigated in the ternary (NiO-WO 3 -Mg, NiO-WO 3 -C) and binary (NiWO 4 -Mg, NiWO 4 -C) systems, then in a complex quaternary (NiO-WO 3 -Mg-C) and ternary (NiWO 4 -Mg-C) systems, under identical heating conditions. The research data on the previously implemented systems (WO 3 -Mg, WO 3 -C, WO 3 -Mg-C, NiO-Mg, NiO-C, NiO-Mg-C) were also considered [32,33].…”

Section: Resultsmentioning

confidence: 99%

“…According to recent research carried out by our research group [33], the carbothermic reduction of nickel oxide began at 950 • C, and by 1030 • C a complete reduction had already been achieved (β = 300 • C min −1 ). At low heating rate region (β = 2.5-20 • C min −1 ), the carbothermic reduction of nickel oxide occurs with two sequential endothermic stages noticeable from the DTA, TG and DTG (Derivative Thermogravimetric) curves at 780-900 and 905-985 • C temperature ranges [30].…”

Section: Nio-wo 3 -C and Niwo 4 -C Systemsmentioning

confidence: 98%

“…On the other hand, according to [33], only a partial reduction of nickel oxide by Mg was possible at temperatures up to 1200 °C at heating rate β = 300 °C min −1 . Therefore, the complete magnesiothermic reduction of the both metals at 1300 °C becomes possible due to the combined processing of nickel and tungsten oxides.…”

Section: Nio-wo 3 -Mg and Niwo 4 -Mg Systemsmentioning

confidence: 99%

“…In contrast to the magnesiothermic reduction of the NiO + WO3 mixture, the carbothermic reduction proceeded partially at the studied temperature interval (up to 1300 °C): carbon reduced NiO up to Ni, while WO3 was endothermically reduced over WO2.7 up to WO2 (Figure 2). According to recent research carried out by our research group [33], the carbothermic reduction of nickel oxide began at 950 °C, and by 1030 °C a complete reduction had already been achieved (β = 300 °C min −1 ). At low heating rate region (β = 2.5-20 °C min −1 ), the carbothermic reduction of nickel oxide occurs with two sequential endothermic stages noticeable from the DTA, TG and DTG (Derivative Thermogravimetric) curves at 780-900 and 905-985 °C temperature ranges [30].…”

Section: Nio-wo 3 -C and Niwo 4 -C Systemsmentioning

confidence: 99%

See 4 more Smart Citations

Joint Reduction of NiO/WO3 Pair and NiWO4 by Mg + C Combined Reducer at High Heating Rates

Zakaryan

Nazaretyan

Aydinyan

et al. 2021

Metals

View full text Add to dashboard Cite

Functional features of Ni-W composite materials combined with successful performance enabled a breakthrough in their broad application. To disclose the formation pathway of Ni-W composite materials at extreme conditions of combustion synthesis in the NiO-WO3-Mg-C and NiWO4-Mg-C systems for the optimization of the synthesis procedure, the process was modeled under programmed linear heating conditions by thermal analysis methods. The reduction kinetics of tungsten and nickel oxides mixture and nickel tungstate by Mg + C combined reducer at non-isothermal conditions was studied at high heating rates (100–1200 °C min−1) by high-speed temperature scanner techniques. It was shown that when moving from low heating to high heating rates, the mechanism of both the magnesiothermic and magnesio-carbothermic reductions of the initial mixtures changes; that is, the transition from a solid-solid scheme to a solid-liquid scheme is observed. The strong influence of the heating rate on the reduction degree and kinetic parameters of the systems under study was affirmed. The simultaneous utilization of magnesium and carbon as reducers allowed the lowering of the starting and maximum temperatures of reduction processes, as evidenced by the synergetic effect at the utilization of a combined reducer. The effective values of activation energy (Ea) for the reactions proceeding in the mixtures NiO + WO3 + 4Mg, NiO + WO3 + 2.5Mg + 1.5C, NiWO4 + 4Mg and NiWO4 + 2Mg + 2C were estimated by Kissinger isoconversional method and were 146 ± 10, 141 ± 10, 216 ± 15 and 148 ± 15 kJ mol−1, respectively.

show abstract

Section: Calculation Of Activation Energymentioning

confidence: 55%

Section: Resultsmentioning

confidence: 99%

Section: Nio-wo 3 -C and Niwo 4 -C Systemsmentioning

confidence: 98%

Section: Nio-wo 3 -Mg and Niwo 4 -Mg Systemsmentioning

confidence: 99%

Section: Nio-wo 3 -C and Niwo 4 -C Systemsmentioning

confidence: 99%

See 3 more Smart Citations

Joint Reduction of NiO/WO3 Pair and NiWO4 by Mg + C Combined Reducer at High Heating Rates

Zakaryan

Nazaretyan

Aydinyan

et al. 2021

Metals

View full text Add to dashboard Cite

show abstract

Spontaneous Crystallization for Tailoring Polymorphic Nanoscale Nickel with Superior Hardness

et al. 2022

View full text Add to dashboard Cite

Hexagonal close-packed (hcp) Ni exists only on a nanometric scale and readily converts into the stable face-centered cubic (fcc) polymorph. This work reports a spontaneous crystallization (SC) process in amorphous nanoparticles to tailor polymorphism in nanoscale Ni. The heat generated during the amorphous−crystalline transition enables SC to self-sustain. The combination of thermal analysis methods, X-ray photoelectron spectroscopy, electron microscopy, and diffraction methods with molecular dynamics (MD) simulations allows us to reveal the mechanism of the SC. This process consists of multiple exothermic steps: nuclei formation and growth of hcp/fcc-Ni grains within the amorphous nanoparticles, neck formation between particles, and defect-stimulated recrystallization (grain growth). The use of SC in conjunction with a rapid (minutes) and low-temperature (780 K) processing method allows for obtaining compact (94 ± 2% relative density) hcp/fcc-Ni nanomaterials. Rapid cooling during this process prevents the hcp → fcc phase transition, making it possible to preserve the metastable hcp-Ni phase. hcp/fcc-Ni materials possess a unique nanostructure and superior hardness to single-phase fcc-Ni. Detailed high-resolution imaging results show that hcp-Ni can be found in round-shape (less than 10 nm) or ultrathin (0.5−5 nm) laminated grains. Ultrasmall features reduce the dislocation motion at grain boundaries and significantly enhance the hardness of these materials.

show abstract

The Mechanism of Joint Reduction of MoO3 and CuO by Combined Mg/C Reducer at High Heating Rates

et al. 2021

View full text Add to dashboard Cite

Understanding of the decisive role of non-isothermal treatment on the interaction mechanism and kinetics of the MoO3-CuO-Mg-C system is highly relevant for the elaboration of optimal conditions at obtaining Mo-Cu composite powder in the combustion processes. The reduction pathway of copper and molybdenum oxides with combined Mg + C reducing agents at high heating rates from 100 to 5200 K min−1 was delivered. In particular the sequence of the reactions in all the studied binary, ternary and quaternary systems contemporaneously demonstrating the effect of the heating rate on products’ phase composition and microstructure was elucidated. The combination of two highly exothermic and speedy reactions (MoO3 + 3Mg and CuO + Mg vs. MoO3 + CuO + 4Mg) led to a slow interaction with weak self-heating (dysynergistic effect) due to a change in the reaction mechanism. Furthermore, it has been shown that upon the simultaneous utilization of the Mg and C reducing agents, the process initiates exclusively with carbothermic reduction, and at relatively high temperatures it continues with magnesiothermic reaction. The effective activation energy values of the magnesiothermic stages of the studied reactions were determined by Kissinger isoconversional method.

show abstract

NiO reduction by Mg + C combined reducer at high heating rates

Cited by 7 publications

References 35 publications

Joint Reduction of NiO/WO3 Pair and NiWO4 by Mg + C Combined Reducer at High Heating Rates

Joint Reduction of NiO/WO3 Pair and NiWO4 by Mg + C Combined Reducer at High Heating Rates

Spontaneous Crystallization for Tailoring Polymorphic Nanoscale Nickel with Superior Hardness

The Mechanism of Joint Reduction of MoO3 and CuO by Combined Mg/C Reducer at High Heating Rates

Contact Info

Product

Resources

About