Carbon activity measurement using a solid state potentiometric cell: Application to boron carbides

Abstract

The interface between fl-alumina and carbonaceous materials has been studied from both thermodynamic and electrochemical viewpoints. Based on the results, a solid electrolyte potentiometric cell has been devised and the conditions enabling carbon activity to be measured have been determined. In spite of the chemical inertness of the materials involved, the measurements must be performed at low temperature (T < 720 K). Carbon activity measurements in the boron-carbon system are presented.

Sodium‐Aluminum‐Oxygen Phase Diagram and its Application to Solid‐State Electrochemistry

“…In our investigation of the B-C system (35,36), where we have detected the presence of B203 impurities, the oxygen partial pressure could be imposed by the B-B203 system, i.e., of the order of 10 -35 atm at 1000 K. According to Fig. 6c, the corresponding p(Na) is then in the 10 4-10-5 atm range.…”

“…6c, the corresponding p(Na) is then in the 10 4-10-5 atm range. Another possibility in the study of carbides is the quantitative conversion of oxygen impurity present in the cell atmosphere or in the electrode compartment into CO/CO2 mixtures (36). For instance, at 1000 K, the conversion of 10 -6 tool 02 into CO(g) corresponds to a real oxygen partial pressure of about 10 -37 atm (Fig.…”

Control of Oxygen Partial Pressure by means of H[sub 2]–H[sub 2]O–O[sub 2] or CO–CO[sub 2]–O[sub 2] Gas Mixtures

“…When working at intermediate p O 2 conditions, a sample and an oxygen sensor may be exposed to very different p O 2 values because of the presence of p O 2 gradients in the gas mixture and within the Pt electrode itself. 11 The low concentration of H 2 ͑CO͒ and O 2 at these conditions may also produce sluggish surface reactions, resulting in nonequilibrium states between sample and gas phase. The study of Patrekeev et al 12 on the transport properties of La 1−x Sr x FeO 3−␦ showed that there existed nonequilibrium states between gas and solid phase at intermediate p O 2 conditions.…”