Synthesis of cerium oxalate hydrate by precipitation technique under external magnetic field

Cerium oxalate hydrate particles were synthesized by precipitation technique under external magnetic field with respective intensities of 0,0.1,0.3,and 0.6 T.The particle morphologies were investigated by scanning electron microscopy(SEM)and transmission electron microscope(TEM).Results show that external magnetic field has a great influence on the growth behavior of cerium oxalate hydrate particles.Rod-like and plate-like cerium oxalate hydrate particles with smaller size are formed without the applying of external magnetic field.However,the extremely big rod-like particles with the average size of 12.47μm were prepared under external magnetic field of 0.6 T.The increasing magnetic field intensity makes the grain grow quickly.Thermogravimetric analysis supports the presence of 8.5 H_(2)O molecules associated with cerium oxalate.Further,the growth mechanism of cerium oxalate hydrate under external magnetic field was briefly discussed.

Effect of zirconium addition on the austenite grain coarsening behavior and mechanical properties of 900 MPa low carbon bainite steel

The ultra-fine bainitic microstructure of a 900 MPa low carbon bainitic Cu-Ni-Mo-B steel was obtained by a newly developed relaxation precipitation control （RPC） phase transformation processing. In a pan-cake like prior-austenite grain, the micro- structure consisted of lath bainite, a little of abnormal granular bainite, and acicular ferrite. The effect of zirconium carbonitrides on the austenite grain coarsening behavior was studied by transmission electron microscopy （TEM）. The results show that, the lath is narrower with increasing cooling rate. The ratio of all kinds of bainitic microstructure is proper with the intermediate cooling rate; and Zr-containing precipitates distribute uniformly, which restrains austenite grain growing in heat-affected welding zone.