Application of thermal analysis for the investigation of calcium ferrites

Abstract

Investigations of metallurgical materials such as blast furnace sinters and pellets require the syntheses of the standard phases contained in these materials.Synthetic pure and calcium-doped iron oxides were studied Calcium ferrite phases originated in the intergranular space and strongly affected the reducibility of the sinter, besides haematite and magnetite.Studies of the formation and physicochemical properties of the synthetic calcium ferrites CaFe204 and Ca2Fe2Os, identified in polycrystalline calciomagnetite and caiciowustite samples, are described. ExperimentalThe calcioferrites CaFe204 and Ca2Fe205 have been obtained by thermal dissociation [1][2][3][4][5][6] and following the sintering of stoichiometric CaCO3-Fe203 mixtures at 1150 ~ in air [7]. The products were subjected to microscopic and diffractometric examination and also to microregion spectral analysis.In order to determine the conditions of ferrite formation, thermal analyses were carried out with a Q-15000 Paulik-Paulik-Erdey derivatograph. TG, DTG, DTA analyses were performed in air atmosphere, using 500 mg samples. The temperature was increased at a rate of 7.5 deg/min.As can be seen in Fig. 1, the TG and DTG analyses of a 1:1 molar mixture of in the temperature range 525-880 ~ indicate the complex character of the weight loss (16.4%) process. The process involving a slow increase in the weight loss rate between 325 and 825 ~ turns into the next step with an altered rate up to 880 ~ . The complexity of the weight loss process is confirmed by DTA. There are initially endothermic effects conJohn Wiley & Sons, Limited, Chichester Akadgmiai Kind6, Budapest

Signatures in magnetites formed by (Ca,Mg,Fe)CO3 thermal decomposition: Terrestrial and extraterrestrial implications

“…In the present study, low-substituted magnetites would be called (Ca,Mg)-magnetites while high-substituted magnetites would be addressed as (Ca,Mg)-ferrites, following the terminology in Orewczyk (1990) and ThomasKeprta et al (2009).…”

Solid state interactions in the systems CaO(CaCO3)-Fe2O3 and CuFe2O4-CaO

“…There are data that contradict these facts, however. It has been found that the dicalcium ferrite forms at a higher temperature than the monocalcium ferrite [17]. Other authors point that in the system CaCO 3 -Fe 2 O 3 after thermal treating and quick cooling a mixture is formed that consists of various types of ferrites -50 % CF 2 , 20 % CF, 5-8 % C 2 F and Fe 2 O 3 [18].…”