منابع مشابه
Metal Carbides for Biomass Valorization
Transition metal carbides have been utilized as an alternative catalyst to expensive noble metals for the conversion of biomass. Tungsten and molybdenum carbides have been shown to be effective catalysts for hydrogenation, hydrodeoxygenation and isomerization reactions. The satisfactory activities of these metal carbides and their low costs, compared with noble metals, make them appealing alter...
متن کاملThe Effect of sintering temperature on microstructure and hardness of milled WC- 20 wt.% equiatomic (Fe,Co) cemented carbides
In this study, WC–20 wt.% equiatomic (Fe,Co) powder mixture was milled in a planetary ball mill. The effects of different milling time (15 min, 5h, 10h, and 25 h) and sintering temperatures on the microstructure and mechanical properties of this equi-Fe substituted cermet were investigated. The structural evolution and the crystallite size changes of the powders during milling were monitored by...
متن کاملCemented Carbides – a Success Story
After WW2, a huge market opened in the growing economies and cemented carbides contributed as tool materials and construction parts to their industrial development. Today, cemented carbides are the workhorses in all areas of the manufacturing industries: no factory without cemented carbide tools; no production of glass bottles, aluminium cans or plastic tubes which has not benefited from these ...
متن کاملAccuracy of Standard Blocks for Hardness and Uncertainty of Hardness
− The authors numerically discuss the accuracy of the hardness values of standard hardness blocks by evaluating the uniformity of hardness blocks and the resolution of hardness values according to test method. As a result of reviewing the results of this evaluation and the reasonability of the currently proposed method for evaluating the uncertainty of hardness values, it is revealed that the v...
متن کاملHardness for Hypergraph Coloring
We show that it is quasi-NP-hard to color 2-colorable 8-uniform hypergraphs with 2(logN) 1/10−o(1) colors, where N is the number of vertices. There has been much focus on hardness of hypergraph coloring recently. In [17], Guruswami, H̊astad, Harsha, Srinivasan and Varma showed that it is quasi-NP-hard to color 2-colorable 8-uniform hypergraphs with 22Ω( √ log logN) colors. Their result is obtain...
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ژورنال
عنوان ژورنال: Nature
سال: 1969
ISSN: 0028-0836,1476-4687
DOI: 10.1038/221494a0