Electrochemical magnesium sensors for Use in aluminum processing

Solid-State Electrochemical Sensor for Monitoring Mg in Al Refining Process

“…Therefore, it is important to know whether the solid electrolyte materials used in designing solid-state sensors will be stable enough to warrant their use as a solid electrolyte. There is no information in the literature on thermodynamics of formation of MgZr 4 (PO 4 ) 6 and also the phase relations ECS Transactions, 1 (13) 1-11 (2006) in the oxide systems consisting this compounds is not available. Gibbs energy of formation of MgAl 2 O 4 measured recently by Jacob et al (11) suggests that the spinel compound will be stable at the extremely low oxygen potentials prevailing in molten aluminium and it's alloys at 1000 K. Therefore, instead of determining the thermodynamic stability of MgAl 2 O 4 and MgZr 4 (PO 4 ) 6 solid electrolyte materials, it was decided to fabricate the Mg sensors using the above electrolytes and observe the response of the sensors as a function of time and concentration of Mg in molten aluminium at around 1000 K. The signature of the chemical instability of the solid electrolyte material can be easily identified from the plot of emf versus time.…”

“…Gibbs energy of formation of MgAl 2 O 4 measured recently by Jacob et al (11) suggests that the spinel compound will be stable at the extremely low oxygen potentials prevailing in molten aluminium and it's alloys at 1000 K. Therefore, instead of determining the thermodynamic stability of MgAl 2 O 4 and MgZr 4 (PO 4 ) 6 solid electrolyte materials, it was decided to fabricate the Mg sensors using the above electrolytes and observe the response of the sensors as a function of time and concentration of Mg in molten aluminium at around 1000 K. The signature of the chemical instability of the solid electrolyte material can be easily identified from the plot of emf versus time. The emf as a function of time of the Mg sensor incorporating MgZr 4 (PO 4 ) 6 and MgAl 2 O 4 as a solid electrolyte is shown in Fig. 4 and 5, respectively.…”

“…The solid electrolyte materials such as MgAl 2 O 4 and MgZr 4 (PO 4 ) 6 have been synthesised by the solid-state ceramic route at elevated temperatures from the precursor powders that were mixed in appropriate molar ratios. The precursor powders were mixed under acetone using a high-energy ball mill for a period of 30 minutes.…”

Study of the Thermodynamic Properties of the Al-Mg Binary System Between 973-1073 K by the EMF Method

“…If there were a logarithmic relation between the EMF of the sensor and the Mg concentration in Al, the designed sensor can be used directly to determine Mg content in Al melt. Many researchers have used this method to determine the Mg concentration in the melt [7][8][9]. By injecting chlorine, the Mg of the Al melts is removed to reach a desirable amount.…”

High‐Temperature Sensor for In‐Line Monitoring of Mg and Li in Molten Al Employing Ion‐Conducting Ceramic Electrolytes

“…Tiwari and Howie, 1 Belton and Rao, 2 and Tsyplakove and Strelets 3 used molten MgCl 2 , a Mg 2+ ion conductor, as an electrolyte for sensing Mg in molten Al and to deduce the thermodynamic properties of dilute Al‐Mg liquid alloys containing less than 0.15 atomic fraction Mg. Larose, et al 4 used 1‐2 wt% MgO stabilized Na‐ß‐Al 2 O 3 , a Na + ion conductor, as a solid electrolyte to sense Mg in molten Al. Fergus and coworkers 5,6 used MgF 2 , a F ion conductor, as a solid electrolyte for sensing Mg in molten Al. More recently, Zhang and Fray 7 used immobilized MgCl in porous MgO thimble as an electrolyte for sensing Mg in molten Al.…”