Tungsten Oxide

Nanocrystalline cemented carbide is a tool material developed in recent years. It is based on nano tungsten carbide powder . The cemented carbide with high hardness, high wear resistance and high toughness has been produced under the condition of adding proper binder and grain growth inhibitor, its performance is obviously higher than that of conventional cemented carbide. It has been widely used in hard metal materials, cutting tools, micro drills in the electronics industry, precision molds, medical fields and other fields. In the aspect of ultrafine or nanocrystalline cemented carbide, there are only a few countries in the world such as the United States, Japan, Sweden and so on, which can produce alloy with both high hardness (HRA>90) and high strength (>3 200 MPa). The main difficulties come from ultrafine and nano tungsten carbide powder and other raw materials and cemented carbide production process. From 70 to 80s in China began to study the industri...

Ozonolysis is of great interest to synthetic organic chemistry because it is one of the most efficient tools for oxidatively cleaving carbon-carbon double bonds. Ozonolysis is generally used to prepare biologically active molecules. Therefore, the reactions between ozone and organic compounds continue to be a subject of significant interest from mechanistic, synthetic, and environmental perspectives. The importance of O 3  reactions with alkenes in the troposphere and solution has led to many experimental and theoretical studies of their kinetics and mechanism. Scientists addresses tungsten oxide nanoparticle syntheses for use as a catalyst in the novel one-step malonic acid ester synthesis. Malonic acid ester is directly synthesized and esterified via the ozonolysis of palm olein (palm oil fraction), which comprises 10% linoleic acid as an unsaturated fatty acid. The main advantages of using tungsten oxide nanoparticles as the catalyst for this esterification are to shor...

Metal oxide semiconductors (MO S ) have been utilized as gas sensing active materials for half a century. One of the most promising solid-state MO S  chemo sensors is n-type semiconducting tungsten oxide-based  gas  sensor.  They  have  demonstrated  novel sensing  properties  such  as  high  sensitivity,  fast response  time  and  low  operation  temperature.  In particular,  pure  or  doped  tungsten  oxide  is  a  promising material for the detection of various substances, e.g., H 2 ,H 2 S,NOx, NH 3  and ethanol. Scientists have investigated  the sensing characteristics  of   tungsten oxide   nanoparticles  to H 2 S  in  the 7 to 200 ppm range at working temperatures of the range of 100–225 ℃.  Semiconductor  gas  sensors  based  on nanocrystalline  WO 3   powders  we...

Nanostructures such as nanowires, nanorods, nanotubes of metal oxide semiconductor (MO S ) materials have recently attracted monumental interest in gas-sensing applications because of their excellent performances owing to their large surface to vol-ume ratio, lower electron recombination rate and high stability. Among various MO S  materials, tungsten trioxide (WO 3 ) is a highly promising candidate due to its fast response with high sensitivity toward NO x . Glancing angle depositio (GLAD) technique is a relatively new method for fabrication of well-ordered and sophisticated nanostructures i.e. nanorods, nanoblade and zigzag nanocolumns. It is a modified physical vapor deposition process, in which substrate surface is rotated and tilted to an angle greater than 80° with respect to the normal of substrate surface or less than 10°with respect to the direction of vapor flux. The vapor molecules directed to the substrate will experience shadowing and limited surface diffusion c...

USTC(University of Science and Technology of China) recently announced that professor Xiong Yujie research group designed a kind of nano structure tungsten oxide in defect state based on inorganic solid accurate preparation of chemical and use crystalline defect project. Under broad spectrum illumination, it shows fine oxidation coupling catalytic property which is expected to realize low cost and low-energy organic chemical technology. Tungsten oxide has good photocatalytic property due to its special structure, it has already been used as varies of catalyst and also other industrial fields.  Most of catalytic reaction is based on the application of precious metal oxide and motivated by burning of petroleum and coal. It has disadvantages of high cost and high energy consuming. Compared to precious metal catalyst, metal oxide has benefits of low cost. However, it shows shortcomings in oxygen molecular system which can not capture solar energy and pass it into oxygen molecular...

The metabolic syndrome is associated with increased obesity caused by a group of common metabolic disorder syndrome, the fundamental reason is the imbalance of body energy metabolism. With the improvement of people's standard of living, when the body intake of excessive nutrition and energy use is reduced, the remaining nutrients are stored in the body in the form of fats and glycogen, and excessive fat storage causes obesity. Obesity is the cause of many chronic conditions, it will significantly increase the incidence of diabetes, coronary heart disease, stroke, hypertension, hyperlipidemia and other morbidity and mortality. So far, only two drugs have been approved and accepted for obesity in FDA of the United States: Orlistat and Sibutramine. So people can lose weight better and control their appetites, but synthetic diet pills have side effects, such as headaches, anorexia and gastrointestinal reactions, and western medicine is expensive. In recent years, res...

As we all know, the main raw material of glass is silica, namely quartz, the main raw material of ceramics is kaolin. Coincidentally, the main component of tungsten tailings is also silicon, and may be rich in other kaolin constituents. In the eyes of scientists and technicians, most of the composition of tungsten tailings and glass ceramic raw materials are similar, do not need too complicated to deal with, can be processed into glass ceramics. Some scholars have prepared glass ceramics by using tungsten tailings after magnetic separation to remove iron, by changing the temperature system in sintering process, the glass ceramics with better properties were obtained, and the crystallization kinetics of glass-ceramic during sintering was further explored. The crystallization temperature is adjusted between 950~1100 °C, the results show that the main crystalline phases of glass ceramics are calcium feldspar and iron pyroxene. The crystalline phase number and grain siz...

Tungsten tailings are the wastes left in the production of mines. China is a big producer of tungsten resources. It is said that all large tungsten mines have a large number of tailings reservoirs, and the tailings reservoirs accumulated over several decades or even centuries have become too large to imagine. Some tailings which have reached the marginal grade can be extracted again, but most of the tailings are no longer meaningful. How to find a way out for these tailings? Tailings treatment has always been a thorny problem in mining enterprises, not only copper and iron, tungsten ore also racking their brains for tailings to find a new way out, the most common tungsten tailings application is the manufacture of cement, tile. However, with the development of industrial technology, people found that it is a waste that tungsten tailings are used to make cement and bricks. In recent years, scientists have invented a material between ceramic and glass, which has remarkabl...