Hongwei Zhu

High chromium and nickel indefinite chilled cast iron (ICCI), as an excellent hot roll material, is the preferred roll variety due to its good combination of surface roughness, hot crack resistance, and hot wear resistance. The microstructure and hardness of ICCI roll materials with different contents of (NbTi)C particles is studied here, and the microstructure evolution process is analyzed by X-ray diffraction. The influence of (NbTi)C particles on the carbide morphology and distribution is investigated by metallographic microscopy and scanning electron microscopy, and the existence of (NbTi)C particles is observed. The experimental results show that (NbTi)C particles are present in granular, rod, and polygonal forms. Combined with a Thermo-Calc solidification phase diagram, it is found that the (NbTi)C particles undergo eutectic precipitation in the melt, forming short rod-shaped (NbTi)C carbides with a size of about 10 μm. Through the Rockwell hardness test, it is found that the hardness after adding 0.8 wt % (NbTi)C particles was 54.4 HRC, which was 21.1% higher than that without the addition.

Self-designed (NbTi)C nanoparticles were obtained by mechanical alloying, predispersed in Fe powder, and then added to 1045 steel to obtain modified cast steels. The microstructure of cast steels was investigated by an optical microscope, scanning electron microscope, X-ray diffraction, and a transmission electron microscope. The results showed that (NbTi)C particles can be added to steels and occur in the following forms: original ellipsoidal morphology nanoparticles with uniform dispersion in the matrix, cuboidal nanoparticles in the grain, and microparticles in the grain boundary. Calculations by Thermo-Calc software and solubility formula show that cuboidal (NbTi)C nanoparticles were precipitated in the grain, while the (NbTi)C microparticles were formed by eutectic transformation. The results of the tensile strength of steels show that the strength of modified steels increased and then declined with the increase in the addition amount. When the addition amount was 0.16 wt.%, the modified steel obtained the maximum tensile strength of 759.0 MPa, which is an increase of 52% compared with to that with no addition. The hardness of the modified steel increased with the addition of (NbTi)C nanoparticles. The performance increase was mainly related to grain refinement and the particle strengthening of (NbTi)C nanoparticles, and the performance degradation was related to the increase in eutectic (NbTi)C.

Phoxim is a significant insecticide, and its current synthesis method has some shortcomings such as the high risk of explosion and the trans structure (main impurity) is hard to control. Our work solved the above disadvantages by introducing macromolecular alcohol (benzyl alcohol, etc.) as the starting material and optimizing the intermediate reaction conditions. Compared with the current synthesis route, the synthetic method has the following advantages: (1) intermediate benzyl nitrite has a high boiling point and strong safety; (2) intermediate α -cyanobenzaldehyde oxime sodium are almost (≥99%) cis structure, and no further refinement was required, which greatly reduced the amount of waste water produced; and (3) The high yield of phoxim was maintained at 72.9%.