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REB2C2 (RE = Y and lanthanides) compounds have gained attention for their unique layered crystal structure. However, there have been few reports about Raman spectroscopy of REB2C2 compounds up to now. Here, the Raman spectrum of YbB2C2 is obtained by a micro-Raman spectroscope and the first-principles calculations. Raman active vibrational modes of YbB2C2 are confirmed as A1g (627 and 1311 cm−1), B1g (944 and 1172 cm−1), B2g (330 and 885 cm−1) and Eg (357 and 530 cm−1). Atomic displacements of these modes are different, they can be divided into two groups: A1g, B1g and B2g correspond to ring breathing (δin, in the plane) of B2C2 layer; Eg is due to ring deformation (δoop, out of the plane) of B2C2 layer. These results are helpful to understand the individual structure of REB2C2.

A phase transformation model was presented for predicting the phase fraction transformed and the carbon concentration in austenite for austenite to ferrite transformation during laminar cooling on run-out table in hot rolling strip mill. In this model, the parameter k in Avrami equation was developed for carbon steels. The wide range of chemical composition, the primary austenite grain size, and the retained strain were taken into account. It can be used to predict the ferrite volume fraction and the carbon concentration in austenite of hot-rolled steel strip during laminar cooling on run-out table. The coiling temperature controlling model was also presented to calculate the temperature of steel strip. The transformation kinetics of austenite to ferrite and the evolution of carbon concentration in austenite at different temperatures during cooling were investigated in the hot rolled Q235B strip for thickness of 9.35. 6.4, and 3.2mm. The ferrite volume fraction along the length of the strip was also calculated. The calculated ferrite volume fraction was compared with the log data from hot strip mill and the calculated results were in agreement with the experimental ones. The present study is a part of the prediction of the mechanical properties of hot-rolled steel strip, and it has already been used on-line and off-line in the hot strip mill.

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K 2 CrO 4 and Fe 2 O 3 , increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.