Yu Mei Zhou,Feng Lin Zhang,Peng Cheng Li,Kun Bai,Shang Hua Wu
AlMgB14 is a very hard and brittle material which need be modified for utilizing as cutting tool materials. In present study, TiB2 and Ni3Al were used to strengthen and toughen AlMgB14 material. The microstructure of the AlMgB14-TiB2-Ni3Al composites was analysized by scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX) and an X-ray diffractometer (XRD). The hardness and fracture toughness of the AlMgB14-TiB2Ni3Al composites were also examined. The results showed that the major phases in AlMgB14-Ni3Al composites were TiB2, AlMgB14, MgAl2O4 , Ni3Al and NiAl. With the increasing of the amount of Ni3Al, more intergranular fractured features can be found in the fractured surface of the composites, the hardness and fracture toughness of the composites were both decreased comparing to the synthesised AlMgB14. The AlMgB14-TiB2-4wt.% Ni3Al composite has a hardness of 28.1 Gpa and a fracture toughness of 3.14 MPa·m1/2.
Jiamin Wang,Tengjuan Ma,Yulong Ma,Jinpeng Wei,Haiyan Yan,Yonggang Sun
In recent years, developing highly active non-noble metal catalysts for biomass hydrodeoxygenation (HDO) to achieve value-added conversion has attracted significant attention. However, major challenges remain in catalyst efficiency, stability, and the precise control of reaction pathways.In this study, a synergistic Ni-W-Cu mixed metal oxide (MMO) catalyst was prepared from LDH precursors via a stepwise "ion exchange-active site introduction" strategy. Under optimized conditions (240 ℃, 2.5 MPa H 2 , 2.5 h), the catalyst achieved complete cellulose conversion with 72% ethylene glycol selectivity. Even after five reuse cycles, it retained 95.4% conversion and 62% selectivity. Characterization demonstrated that appropriate Cu loading promoted Ni-Cu alloying and modulated Ni electronic structure, which induced abundant W 6 + /W 4+ species and oxygen vacancies (O V ). In this architecture, W 6+ provides Lewis acidity, while W 4+ couples tightly with O V , thereby synergistically enhancing the catalyst's hydrogenation capability and bond-cleavage ability. Density functional theory (DFT) calculations reveal that the strong interaction between W and Cu constructs highly efficient adsorption sites, enabling the precise catalysis of C-O bond scission. These findings suggest that tailoring the W-Cu interplay offers a viable strategy for directing product selectivity. By engineering a stable, multifunctional catalyst for biomass conversion, this study provides a new strategy for constructing high-performance HDO catalysts.
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