Oxidation of phosphated iron powders

Evolution of phosphate coatings during high-temperature annealing and its influence on the Fe and FeSiAl soft magnetic composites

“…Among these coatings, phosphate has been widely used in the fabrication of the SMCs due to its simple preparation process, high electrical resistivity and strong adhesion to the powder surfaces [11][12][13]. A great amount of work has been carried out to study the microstructure and chemical composition [14][15][16][17][18] of the phosphate coating, as well as its optimized preparation procedures for improved properties of the SMCs [3,10].…”

Determination of the oxidation kinetics of modified α‐iron substrate: correlation between TGA and AES

“…According to the square of the weight gain vs. oxidation time plots (Fig. 3 As for phosphated iron powders, two successive parabolic oxidation stages have already been observed; therefore no apparent change in the oxidation kinetics is found, independently of the powder nature 4 or the bulk nature of the iron substrate of this study. This behaviour can be explained by the presence of the phosphate layer on both substrates.…”

“…This temperature has been retained because the two parabolic stages should successively appear during the oxidation experiment. 4 Figures 1 and 2 show the results respectively obtained for untreated and phosphated iron. For untreated iron, all the experimental curves show the same behaviour for the first oxidation times, indicating a good reproducibility of the experiments.…”

“…2,3 Typically, an aqueous solution is employed in the phosphating process, however, it has been found recently that such a treatment performed in an organic solvent significantly increases the oxidation resistance of iron powders in the temperature range 300-700°C. 4 Moreover, it has been established that two successive parabolic stages are necessary to describe the oxidation kinetics. The first stage is responsible for the reduction in oxidation rate, while the second stage agrees well with the oxidation mechanisms of untreated iron.…”

The effect of iron phosphate, alumina and silica coatings on the morphology of carbonyl iron particles

“…Carbonyl iron powders were coated in phosphating solution, which contained acetone (solvent) and orthophosphoric acid (phosphating active agent) in 1 : 9 mole ratio, using the modified precipitating method described by Rebeyrat et al [1,2] Phosphating was carried out by stirring the iron powders in the solution at room temperature for 2 h. Phosphated iron powders were dried at 60 • C for 2 h and calcined at 400…”