The microstructure of AISI 304 austenite stainless steel fabricated by the thin strip casting process were investigated using optical microscope, scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray diffraction (XRD). The microstructures of the casting strips show a duplex structure consisting of delta ferrite and austenite. The volume fraction of the delta ferrite is about 9.74vol% at the center and 6.77vol% at the surface of the casting thin strip, in vermicular and band shapes. On account of rapid cooling and solidification in the continuous casting process, many kinds of inclusions and precipitates have been found. Most of the inclusions and precipitates are spherical complex compounds consisting of oxides, such as, SiO2, MnO, Al2O3, Cr2O3, and FeO or their multiplicity oxides of MnO·Al2O3, 2FeO·SiO2, and 2MnO·SiO2. Many defects including dislocations and stacking faults have also formed during the rapid cooling and solidification process, which is helpful to improve the mechanical properties of the casting strips.
A novel technology of tuyere protection is introduced. The ceramic coat is synthesized by using in-situ combustion process as the internal, external, and nose protecting coat of BF tuyeres. It can effectively protect the tuyeres and reduce heat loss by cooling water. The technology is quick-acting, easy to use, energy-saving and can make tuyeres have long service life. The feasibility of the application of the tuyere ceramic coat is discussed and the energy-saving effect of the tuyere is compared with that of the tuyeres lined with refractory.
YANG Da-zhengGUAN YongZHANG YueLI JingHU Jun-geLI Wen-zhu
First principle calculations have been performed to study the electron structures and magnetic properties of tran- sition metal doped rutiles in order to predict room temperature diluted magnetic semiconductors. Different doping configu- rations have been calculated to find the preferred doping site. The ground state energies of both FM and AFM states have been calculated to study the magnetic coupling between the dopants. The calculation results show the Co doped rutile has a Curie temperature of 1438 K. Co doped rutile films have been prepared on Si substrate by magnetron sputtering. X-ray dif- fraction results show that the deposited film is rutile. Hysteresis loop curves measured by vibration sample magnetization show that the film is ferromagnetic at root temperature.
