Synthesis of vanadium and chromium carbides(V_8C_7–Cr_3C_2) nanocomposite via an in situ precursor m

• 作 者: Zhi-Wei Zhao Wen-Meng Hu Hong-Juan Zheng Fei-Xiao Chen
• 机 构: College of Materials Science and Engineering, Henan University of Technology,
• 出 处: Rare Metals
• 发表日期: 2015年07期
• 关键词: chromium Cr_3C_2 V_8C_7 spherical vanadium nanometer crystallite diffractometry

In situ synthesis method was used to prepare V8C7–Cr3C2nanocomposite.Ammonium vanadate, ammonium dichromate and nanometer carbon black were used as raw materials.The products were characterized by X-ray diffractometry(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), thermogravimetric and differential scanning calorimetry(TGDSC) and X-ray photoelectron spectroscopy(XPS) techniques.The results show that V8C7–Cr3C2nanocomposite with an average crystallite size of 25.4 nm can be synthesized at 1200 °C for 1 h.The synthesis temperature required by the method is at least 200 °C lower than that required by the conventional approaches for preparing vanadium and chromium carbides.The powders show good dispersion and are mainly composed of spherical or nearly spherical particles with a mean diameter of about 30 nm.The weight loss ratio of the precursor throughout the reaction process reaches 58 wt%.Three exothermic peaks and four endothermic peaks occur during the reaction.The surface of the specimen is mainly composed of V, Cr, C and O elements.

In situ synthesis method was used to prepare V8C7-Cr3C2nanocomposite. Ammonium vanadate, ammonium dichromate and nanometer carbon black were used as raw materials.The products were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric and differential scanning calorimetry (TGDSC) and X-ray photoelectron spectroscopy (XPS) techniques. The results show that V8C7-Cr3C2nanocomposite with an average crystallite size of 25.4 nm can be synthesized at 1200 ° C for 1 h. synthesis temperature required by the method is at least 200 ° C lower than that required by the conventional approaches for preparing vanadium and chromium carbides. powders show good dispersion and are mainly composed of spherical or nearly spherical particles with a mean diameter of about 30 nm The weight loss ratio of the precursor throughout the reaction process reaches 58% by weight. Three exothermic peaks and four endothermic peaks occur durin g the reaction. The surface of the specimen is mainly composed of V, Cr, C and O elements.