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Submicrometer vanadium carbide (V8C7) can be synthesized from V2O5 encapsulated in phenol resin. The precursor powders were produced by coating V2O5 powders with phenolic resin shells. Then the precursor powders were roasted at various temperatures from 1173K to 1473K for 2h in a flowing Ar atmosphere. The decomposed carbon from phenolic resin could be used to reduce V2O5. The samples obtained with...
In the present investigation, turning experiments were performed on Ti-6Al-4V alloy with coated (TiN, TiAlN) and uncoated cutting tool inserts with different textured patterns fabricated on the rake surface. Performance of coated and uncoated textured tools were evaluated using machinability and surface characteristic parameters such as cutting forces, micro hardness, surface roughness, chip formation...
Determined by the unique S-Mo-S sandwich layer structure, molybdenite is so chemical inert and hydrophobic that it is quite refractory in hydrometallurgical route. To improve Mo leaching by changing mineral structure of molybdenite prior to leaching might be a potential alternative. In this work, a mineral phase reconstruction (MPR) method is presented to treat molybdenite. The transformation of molybdenum-bearing...
Type IIa large diamond crystals were synthesized in FeNiCo-C system with Ti (Cu) as nitrogen getter by temperature gradient method (TGM) under high pressure and high temperature (HPHT) conditions. Diamonds grew upon (111) facet under 5.4GPa and 1620K while black powder appeared around the growing diamond crystal. And the black powder covered the growing crystals in cap shape and restrained the diamond...
C/N ratios in TiCN-TiC-WC-Cr3C2-Ni cermets can be intentionally modified by changing the composition of the presintering atmosphere. This affects not only the sinterability but also the final microstructure of these materials. Melting occurs at lower temperatures as the nitrogen content of the presintering atmosphere rises. However, the final densities are lower due to the precipitation of free carbon...
The outcome of brazing diamond micro-powder using a crystalline Ni-based alloy is not ideal because of the relatively high melting temperature and relatively poor wetting of the crystalline Ni-based alloy toward the steel substrate. In this study, a brazed diamond micro-powder bur was fabricated using an amorphous Ni-based alloy. Fine grains with an average diameter of about 0.02–0.03μm are formed...
WC grains in WC–Co alloys are shaped as truncated triangular prisms, each with a basal plane of a (0001) truncated triangle and two {11̅00} prismatic planes, one narrower and one wider. This anisotropic shape is related to the polarity of the WC lattice, which comes from the difference in the spacing of the W and C layers in the 〈0001〉 projection. We directly determined the relationship between the...
The effects of nitrided treatment during different sintering stages on the microstructure and mechanical properties of Ti(C, N) based cermets were studied. The results showed that: compared with the sample sintered in vacuum, the surface microstructures of these samples which nitrogen gas was introduced in entire stage, heating stage and final sintering stage changed obviously, the porosity greatly...
Ni-P/nano-WC composite coatings were fabricated through electro brush plating and were reinforced by electric contact strengthening (ECS). Then, the microstructures and properties of the composite coatings were investigated using optical microscopy, field emission scanning electron microscopy (FESEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD) and Vickers hardness testing. The analysis...
Molybdenum alloys are used in a number of commercial, defense, nuclear, and aerospace applications that take advantage of their high melting temperature, good creep resistance, and decent mechanical properties at elevated temperature. Titanium-Zirconium-Molybdenum (TZM) alloys are the most commercially important Mo alloy as they possess substantially higher strength than pure molybdenum while still...
The greater demands on final product quality of powder metallurgy processing have led to an increased demand for metal powders with high quality. In this paper we report the successful preparation of tungsten powder with a near-spherical shape and surface morphology by jet milling process, with the disappearance of agglomeration and the improvement of dispersion, narrow particle size distribution...
Cermets, especially hard metals are materials of wide application in tools due to its excellent properties like hardness and toughness. The aim of this work is to analyze cermets composed mainly of Fe, NbC, and different Al contents, materials under development supplied by CBMM (Companhia Brasileira de Metalurgia e Mineração), in its characteristics and processing. The synthesis for obtaining of starting...
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