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The magnetic properties and thermal stability of melt spun SmCo 6.4 Si 0.3 Zr 0.3 ribbons with various rare-earth (RE) elements substituted for Sm have been investigated. It is verified that the properties' combination of SmCo 7 -based ribbons can be modified by selected RE substitution. The light RE Ce is beneficial for enhancing the saturation magnetization and the remanence, while the coercivity and thermal stability can be significantly improved by heavy REs Gd, Ho, and Er substitutions. The highest room-temperature coercivity of 1467 kA/m was achieved in the Sm 0.7 Gd 0.3 Co 6.4 Si 0.3 Zr 0.3 ribbon. For the temperature range of 27°C-200°C, Gd is the best element for enhancing the thermal stability, and the optimal temperature coefficients α and β are −0.032%/°C and −0.269%/°C, respectively. For the range of 27°C-400°C, Ho is the best element to improve the thermal stability, and the values of α and β are −0.064%/°C and −0.19%/°C, respectively.Index Terms-Coercivity, rare earth (RE), SmCo 7 , thermal stability.

Polypropylene (PP)/magnesium hydroxide (MDH) composite was melt-mixed using a twin-screw extruder. Two types of MDH were used, one with the modification of silane and another without. The rheological behavior was measured by capillary and dynamical rheometer. Microstructure of these composites was observed by SEM. Their flame retardancy was characterized by oxygen index and Horizontal/Vertical burning test. Results showed that shear viscosity and complex viscosity of PP with modified MDH were lower than that of PP with non-modified MDH. SEM results also showed a better dispersion of silane modified MDH in PP matrix. With the increase of MDH content, the oxygen index of composites was increased. When the content was increased to 60 wt%, the composite was UL94 HB and V-1.

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