Selective laser melting of high-performance pure tungsten: parameter design, densification behavior and mechanical properties.

Selective laser melting (SLM) additive manufacturing of pure tungsten encounters nearly all intractable difficulties of SLM metals fields due to its intrinsic properties. The key factors, including powder characteristics, layer thickness, and laser parameters of SLM high density tungsten are elucidated and discussed in detail. The main parameters were designed from theoretical calculations prior to the SLM process and experimentally optimized. Pure tungsten products with a density of 19.01 g/cm3 (98.50% theoretical density) were produced using SLM with the optimized processing parameters. A high density microstructure is formed without significant balling or macrocracks. The formation mechanisms for pores and the densification behaviors are systematically elucidated. Electron backscattered diffraction analysis confirms that the columnar grains stretch across several layers and parallel to the maximum temperature gradient, which can ensure good bonding between the layers. The mechanical properties of the SLM-produced tungsten are comparable to that produced by the conventional fabrication methods, with hardness values exceeding 460 HV0.05 and an ultimate compressive strength of about 1 GPa. This finding offers new potential applications of refractory metals in additive manufacturing.

14-Benzoyl-mesaconine hydro-chloride methanol monosolvate.

The title compound, C(31)H(44)N(3)O(10) (+)·Cl(-)·CH(4)O, is the methanol solvate of 8-benzo-yloxy-,9,11,11a-tetra-hydroxy-6,10,13-trimeth-oxy-3-meth-oxy-methyl-1-methyl-tetra-deca-hydro-1H-3,6a,12-(epiethane-1,1,2-tri-yl)-7,9-methanona-phtho[2,3-b]azocin-1-ium chloride, the amine-protonated hydro-chloride of 14-benzoyl-mesaconine hydro-chloride. The cation has an aconitine carbon skeleton with four six-membered rings of which three display chair conformations and one a boat conformation, and two five-membered rings with envelope conformations. In the crystal, the components are connected into an infinite chain by inter- and intra-molecular O-H⋯O, N-H⋯O and O-H⋯Cl hydrogen bonds.

Flame synthesis of carbon nanostructures on Ni-plated hardmetal substrates.

In this article, we demonstrate that carbon nanostructures could be synthesized on the Ni-plated YG6 (WC-6 wt% Co) hardmetal substrate by a simple ethanol diffusion flame method. The morphologies and microstructures of the Ni-plated layer and the carbon nanostructures were examined by various techniques including scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. The growth mechanism of such carbon nanostructures is discussed. This work may provide a strategy to improve the performance of hardmetal products and thus to widen their potential applications.