scholarly journals Direct oxygen removal technique for recycling titanium using molten MgCl2salt

2016 ◽  
Vol 190 ◽  
pp. 109-126 ◽  
Author(s):  
Toru H. Okabe ◽  
Yuki Hamanaka ◽  
Yu-ki Taninouchi
Keyword(s):  
Molten Salt ◽  
Chemical Potential ◽  
Oxygen Removal ◽  
Electrochemical Technique ◽  
High Grade ◽  
Constant Voltage ◽  
Graphite Electrodes ◽  
Kroll Process ◽  
Deoxidizing Agent ◽  
Removal Technique

Deoxidation of Ti, or direct removal of O dissolved in metallic Ti, is known to be extremely difficult when Mg is used as the deoxidizing agent. This difficulty arises because the chemical potential of O2,pO2, under Mg/MgO equilibrium is high (approximately 10−41atm at 1200 K) and is equivalent to that of Ti containing ∼2 mass% O at 1200 K. Therefore, when deoxidizing Ti to the commercial level of high-grade pure Ti (below 0.05 mass% O) using an Mg reductant at 1200 K, the activity of the reaction product MgO (aMgO) must be decreased to below ∼0.025, which is difficult in practice. In this study, the removal of O in Ti in molten MgCl2salt using an electrochemical technique was examined at ∼1173 K with the objective of obtaining Ti containing less than 0.05 mass% O. Ti samples and graphite electrodes immersed in molten MgCl2served as the cathode and anode, respectively. A constant voltage was applied between the electrodes using an external DC source. Molten MgCl2was employed to produce the deoxidizing agent Mg and to facilitate deoxidation of Ti by decreasing the activity of the reaction product MgO. By applying a voltage of approximately 3.1 V between the electrodes, the chemical potential of Mg in the molten MgCl2was increased at the surface of the Ti cathode, and the Ti samples were deoxidized. The resulting O species, mainly formed O2−dissolved in the molten MgCl2, was removed from the molten salt by reacting with the C anode to form CO (or CO2) gas. Ti wires containing 0.12 mass% O were deoxidized to less than 0.02 mass% O. In some cases, the O concentration in the Ti samples was reduced to the level of 0.01 mass%, which cannot be accomplished using the conventional Kroll process. The possible application of this deoxidation technique to practical industrial recycling processes is discussed.

Thermodynamic Investigation of Ti-H System by Molten Salt Electrochemical Technique

2001 ◽  
Vol 148 (1) ◽  
pp. E38 ◽  
Author(s):  
Tokujiro Nishikiori ◽  
Toshiyuki Nohira ◽  
Yasuhiko Ito
Keyword(s):  
Molten Salt ◽  
Electrochemical Technique ◽  
Thermodynamic Investigation

Refinement of thermodynamic data on GaN

2007 ◽  
Vol 22 (12) ◽  
pp. 3475-3483 ◽  
Author(s):  
K.T. Jacob ◽  
Shwetank Singh ◽  
Y. Waseda
Keyword(s):  
Solid State ◽  
Thermodynamic Data ◽  
Chemical Potential ◽  
Electronic Materials ◽  
Ambient Pressure ◽  
Decomposition Temperature ◽  
Electrochemical Technique ◽  
Limited Information ◽  
Pure Nitrogen ◽  
Temperature Range

Although GaN is one of the important electronic materials of this decade, thermodynamic data for this compound are not known with sufficient reliability. The limited information available is not internally consistent. Measured in this study are high-temperature heat capacities using a differential scanning calorimeter and Gibbs energies of formation employing a solid-state electrochemical technique. The solid-state cell was based on single-crystal CaF2 as the electrolyte and Ca3N2 as the auxiliary electrode to convert the nitrogen chemical potential established by the equilibrium between Ga and GaN into an equivalent fluorine potential. The heat capacity of GaN at ambient pressure can be represented by the equation: CoP / J mol−1 K−1 = 74.424 − 0.00106T + (46720/T2) − (685.9/T0.5), in the temperature range from 350 to 1075 K. The standard Gibbs energy of formation of GaN in the range from 875 to 1125 K can be expressed as: ΔfGo/ J mol−1 (±465) = −128,749 + 115.029 T. This corresponds to a decomposition temperature of 1119 ± 4 K for GaN in pure nitrogen at standard pressure. On the basis of these new measurements and a critical assessment of information that is available in the literature, a refined set of data for GaN in the temperature range from 298.15 to 1400 K is presented.

High Temperature Corrosion of Spray-Atomized FeAl (40at.%) Based Alloys:Immersed in a Molten Salt Mixture of V2O5-Na2SO4

1998 ◽  
Vol 552 ◽  
Author(s):  
M. Amaya ◽  
E. J. Lavernia ◽  
L. Martinez
Keyword(s):  
Weight Loss ◽  
High Temperature ◽  
Molten Salt ◽  
Passive Layer ◽  
High Temperature Corrosion ◽  
Electrochemical Technique ◽  
Salt Mixture ◽  
Protective Oxide ◽  
Metal Base ◽  
Temperature Range

ABSTRACTWe studied the high temperature corrosion of spray atomized and deposited FeAl40at% based intermetallic alloys immersed in a molten salt mixture of 80%V2O 5+20%Na2SO4 (wt%) over the temperature range of 600–900°C. Experiments were realized by the weight loss method and the potentiodynamic polarization electrochemical technique in three different samples: FeA140at%, FeA140+0.lat%B and FeA140+0.lat%B+10at%A12O3. Measurements of weight loss and corrosion current density as a function of the molten salts temperature were obtained and discussed in terms of the passive layer morphology and corrosion products formed during the tests. It was found that the iron aluminide doped with boron and reinforced with alumina particulate was more corrosion resistant in the test temperature range. The weight loss experiments revealed that at 700°C all alloys developed maximum corrosion rate. This behavior was related with the dissolution of protective oxide layer on metal base due the formation of vanadate phases which are highly corrosive at this temperature.

The effect of molten salt on oxygen removal from titanium and its alloys using calcium

2016 ◽  
Vol 52 (7) ◽  
pp. 4120-4128 ◽  
Author(s):  
Yang Xia ◽  
Zhigang Zak Fang ◽  
Pei Sun ◽  
Ying Zhang ◽  
Tuoyang Zhang ◽  
...  
Keyword(s):  
Molten Salt ◽  
Oxygen Removal

Electrochemical synthesis of transition metal oxide nitrides with ε-TaN, δ-NbN and γ′-Mo2N structure type in a molten salt system

2020 ◽  
Vol 75 (1-2) ◽  
pp. 33-40
Author(s):  
Tanja S. Lehmann ◽  
Rainer Niewa
Keyword(s):  
Chemical Analysis ◽  
Molten Salt ◽  
Rietveld Method ◽  
Structure Type ◽  
The Other ◽  
Constant Voltage ◽  
Salt Mixture ◽  
Cubic System ◽  
Tan Δ ◽  
Molten Salt System

AbstractThe three nitrides ε-TaN, δ-NbN and γ′-Mo2N have been synthesized electrochemically from the elements at 450°C in a molten salt mixture LiCl/KCl:Li3N. For all compounds the working electrode consisting of a tantalum, niobium or molybdenum foil was anodically polarized and the system was fed with dry nitrogen. The applied constant voltage was 2.5 V (for ε-TaN), 2.2 V (for δ-NbN), and 2.8 V (for γ′-Mo2N). Chemical analysis on N and O resulted in compositions of TaN0.81(1)O0.13(2), NbN1.17(2)O0.28(1) and MoN0.88(1)O0.11(1), respectively. Lattice parameters of ε-TaN refined by the Rietveld method are a =  519.537(4) and c = 291.021(3) pm. The other two nitrides crystallize in the cubic system (rocksalt type) with a = 436.98(2) pm for δ-NbN and with a = 417.25(2) pm for γ′-Mo2N.

scholarly journals The Electrochemical Mechanism of Preparing Mn from LiMn2O4 in Waste Batteries in Molten Salt

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1066
Author(s):  
Jinglong Liang ◽  
Rui Zhang ◽  
Hui Li ◽  
Le Wang ◽  
Zongying Cai ◽  
...  
Keyword(s):  
Molten Salt ◽  
Electrochemical Reduction ◽  
Deionized Water ◽  
Reduction Mechanism ◽  
Constant Voltage ◽  
Intermediate Products ◽  
Electrochemical Mechanism

The electrochemical reduction mechanism of Mn in LiMn2O4 in molten salt was studied. The results show that in the NaCl-CaCl2 molten salt, the process of reducing from Mn (IV) to manganese is: Mn (IV)→Mn (III)→Mn (II)→Mn. LiMn2O4 reacts with molten salt to form CaMn2O4 after being placed in molten salt for 1 h. The reaction of reducing CaMn2O4 to Mn is divided into two steps: Mn (III)→Mn (II)→Mn. The results of constant voltage deoxidation experiments under different conditions show that the intermediate products of LiMn2O4 reduction to Mn are CaMn2O4, MnO, and (MnO)x(CaO)(1−x). As the reaction progresses, x gradually decreases, and finally the Mn element is completely reduced under the conditions of 3 V for 9 h. The CaO in the product can be removed by washing the sample with deionized water at 0 °C.

Kinetic Investigation of the Ti-H System by a Molten Salt Electrochemical Technique

2001 ◽  
Vol 148 (3) ◽  
pp. E127 ◽  
Author(s):  
Tokujiro Nishikiori ◽  
Toshiyuki Nohira ◽  
Yasuhiko Ito
Keyword(s):  
Molten Salt ◽  
Electrochemical Technique ◽  
Kinetic Investigation
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