Microstructure and Isothermal Oxidation of Ir–Rh Spark Plug Electrodes

Abstract

High-temperature oxidation tests were performed on pure iridium, rhodium, and the iridium alloys, IrRh10, IrRh25, and IrRh40, at 1100 °C in a stable air environment for 60 h. The results of the oxidation were analyzed by X-ray photoelectron spectroscopy (XPS). Microstructural changes of the Ir–Rh alloys were characterized by scanning electron microscopy (SEM). XPS analysis results show that the main oxide of the Ir–Rh alloy in a 1100 °C environment was Rh2O3, and SEM analysis shows that the surfaces of the Ir–Rh alloys after oxidation formed both linear and ellipse-shaped corrosion pits, and had the same direction with the wire-drawing process. The oxidation behavior of Ir–Rh alloys, including the mass change, the reason for the mass loss, and the role of Rh in improving oxidation resistance performance, are discussed.

Preparation of Ir/TiO2 Composite Oxygen Evolution Catalyst and Load Analysis as Anode Catalyst Layer of Proton Exchange Membrane Water Electrolyzer

“…Notably, the materials contain Ir species with two different valences, namely, metallic Ir (Ir 0 ) and oxidized Ir (Ir 4+ ). It suggests that some Ir particles were oxidized to hypervalent oxides (IrO x ) or bonded to hydroxyl groups (Ir(OH) x ), and the production of these components may alter the catalytic process of the materials . By calculating the relative intensity area of Ir 0 and Ir 4+ orbital peaks, the content proportions of high-valence Ir in the two materials were compared.…”

High-Performance Ti/IrO2–RhOx–Ta2O5Electrodes for Polarity Reversal Applications

“…In recent years, rhodium oxide (RhOx) has been widely applied as an electrocatalyst due to its high stability and electrocatalytic activity for oxygen evolution. − Alibek prepared Ti/IrO 2 –RhOx-ZrO 2 electrodes with different proportions of RhOx and found that increasing the content of RhOx led to improved service lifetime of the electrode. Swette reported that RhO 2 -coated electrodes with an oxide load of 10 g m –2 are highly stable against oxygen evolution in acidic electrolytes.…”