In all kinds of sintering technology, microwave heating with heating speed, the overall heating, selective heating and non-thermal effects of traditional heat conduction heating methods do not have the characteristics. WC-Co powder compacts have good coupling absorption to microwave, and the penetration depth of microwaves in the compacts of the mixture is very large. Therefore, the preparation of high-performance tungsten carbide by microwave sintering technology has the traditional heat conduction heating preparation method Unmatched advantages. These advantages are shown in the following aspects: 1, micro-high-performance wave heating fast, holistic not only can significantly shorten the preparation cycle and reduce the sintering temperature, simplifying the process, and can prepare a uniform microstructure, grain Small material. 2, because of the high energy efficiency of microwave and its environment-friendly features, it can at lower cost and less environmental pollution to create greater economic value. 3, the characteristics of microwave heating is very conducive to the development of nano-fine grain hard alloy, gradient cemented carbide, carbide coating and other new high-performance carbide. These advantages make the development of tungsten carbide and microwave sintering technology combined into an inevitable trend.

The WC-Co high performance tungsten carbide was successfully prepared by microwave sintering at the University of Pennsylvania. Compared with the traditional sintering method, microwave sintering can obtain the same degree of shrinkage at lower sintering temperature and shorter holding time. The sintered samples have the same degree of shrinkage in the three dimensional direction, while the traditional sintering method in the vertical direction And the microwave sintered samples have more fine WC grains and more uniform Co phase distribution than the traditional sintered samples. The hardness is higher and the chemical corrosion performance is better. In addition, it was found that there were almost no W atoms in the bonding phase of microwave sintered samples, which was very different from the case of the traditional sintered samples with about 20 wt% W atoms.

Dortmund University of Germany, using W, C and Co mixed powder crushed to microwave sintering, compared to the traditional process of WC and Co mixture briquette sintering, this process not only the synthesis of WC powder and WC-Co green compact Sintering two steps together, effectively simplifying the process, shortening the production cycle of cemented carbide, but also make full use of the carbon atoms in the WC between the release of heat, reducing the energy consumption of sintering. The high-performance tungsten carbide materials obtained by this process are denser, the organization is more compact, and the mechanical properties are improved.


 

The results show that the pure magnetic field heating can not complete the post-sintering of the alloy, because at 1100 ℃ above, the Co in the alloy will change from ferromagnetism to paramagnetism, so that the magnetic field can absorb the microwave magnetic field collapse, so that the magnetic field loss to temperature The sintering temperature of the alloy sample can not be increased continuously. However, WC-Co cemented carbide induction of microwave electromagnetic field mainly in the form of dielectric loss, therefore, the use of pure electric field and electromagnetic hybrid field heating can complete the whole densification of the alloy, and the prepared alloy has a good mechanics The WC grains in the microstructure are uniform, and the Co phase is evenly distributed, forming a good lattice structure.

In addition, for the decarburization in the sintering process, studies have shown that by adding carbon black in the mixture and adding carbon black in the filler can inhibit this decarbonization phenomenon, thereby enhancing the performance of microwave sintered cemented carbide. The results show that when the amount of carbon black is 0.4% (mass fraction), the flexural strength of the alloy is up to 2250 MPa. When the carbon black is added into the filler, the bending strength can be increased to 3172 MPa.

Under the effect of National Day’s holiday, although some enterprises are still waiting to stimulate tungsten market, raw material market is in nervous status, manufacturers only purchase raw material without selling. Dealing amount is decreasing.

WC and Co by the composition of tungsten cobalt-based carbide with excellent hardness and wear resistance and other properties, is a widely used tools, structural materials. However, there is a rejection phenomenon between the transverse rupture strength and the hardness in the tungsten-cobalt type cemented carbide, that is, the hoisting strength will damage the hardness, and the hardness will be weakened by the increase of the hardness. This is a technical problem that has been difficult to solve. The results show that the microstructure with ultra-fine grain characteristics of tungsten and cobalt type cemented carbide, can achieve strength and hardness of the synchronous upgrade; general requirements, the grain size of 0.2 to 0.5 microns of tungsten cobalt-based hard alloy can be called super Fine grain hard alloy. However, in the sintering stage of the preparation of WC-Co cemented carbide, grain growth occurs. In order to achieve tungsten cobalt-based carbide fine grain size, generally from two aspects. Conventional method is to WC and Co mixed powder as raw materials, milling after mixing granulation, and then press forming, and then pressure sintering. In order to avoid grain growth, the grain growth inhibitor such as VC and Cr2C3 was added to the mixed powder. Another idea is the use of small grain size of WC-Co composite powder as raw material. The WC-6% Co composite powder prepared by spray-transformation, calcination and low-temperature reduction carbonization process was used as the raw material. The average grain size was below 50 nm and the distribution was uniform. The ultrafine WC-Co tungsten carbide with grain size of about 400 nm was successfully prepared by wet grinding, forming and pressure sintering without adding grain growth inhibitor, and good results were obtained.

The microstructures of the composites prepared by the composite powders show that the size of WC grains is smaller than 0.5 micrometers, and the size distribution of WC grains is uniform. Bonding, bridging phenomenon is greatly reduced, part of the grain edges and corners dissolved dissolved, the edge is more smooth, so that the application of the alloy is not prone to excessive concentration of stress. These are beneficial to improve the mechanical properties of materials. However, the WC grains in the alloy prepared by the traditional method have abnormal growth phenomenon, which will seriously damage the mechanical properties of ultra-fine cemented carbide.

The strength and hardness of ultrafine WC-Co cemented carbide prepared by composite powder were higher than that of the traditional mixed powder preparation. The tensile strength of the composites was 4304N / mm2, which was much higher than that of the samples prepared with mixed powders (3200N / mm2). The hardness of the composite powders was 93.1HRA, which was also superior to that of the mixed powders The hardness of the sample was prepared (91.5 HRA). The results show that the grain size of the composite powder is small, the average grain size is below 50 nm and the distribution is uniform. The component distribution of the composite powder is uniform, and the distribution of W, C and Co is related to the molecular homogeneity. .

Their experiments also found that the composite powder prepared by ultrafine WC-Co cemented carbide prepared with the traditional method of the material in the coercivity value of the significant difference. According to the analysis, when the content of Co in the alloy is the same, as the grain size of WC decreases, the Co phase dispersion increases, the mean free path decreases and the coercive force increases. The coercivity of the composite powder was 34 kA / m, and the sample prepared by the conventional method was 26.7 kA / m. It is also proved that the WC grain size of the ultrafine WC-Co cemented carbide prepared by using composite powder as raw material is smaller than that of the traditional mixed powder.

An international research team has used tungsten oxide thermal metamaterial to control the emission of radiation at high temperatures, an advance that could bring devices able to efficiently harvest waste heat from power plants and factories. Roughly 50 to 60 percent of the energy generated in coal and oil-based power plants is wasted as heat. However, thermophotovoltaic devices that generate electricity from thermal radiation might be adapted to industrial pipes in factories and power plants, as well as on car engines and automotive exhaust systems, to recapture much of the wasted energy. In new findings, researchers demonstrated how to restrict emission of thermal radiation to a portion of the spectrum most needed for thermophotovoltaic technology.

"These devices require spectrally tailored thermal emission at high temperatures, and our research shows that intrinsic material properties can be controlled so that a very hot object glows only in certain colors," said Zubin Jacob, an assistant professor of electrical and computer engineering at Purdue University. "The main idea is to start controlling thermal emission at record high temperatures in ways that haven't been done before." The thermal metamaterial – nanoscale layers of tungsten oxide and hafnium oxide – was used to suppress the emission of one portion of the spectrum while enhancing emission in another.

The basic operating principle of a photovoltaic cell is that a semiconducting material is illuminated with light, causing electrons to move from one energy level to another. Electrons in the semiconductor occupy a region of energy called the valence band while the material is in the dark. But shining light on the material causes the electrons to absorb energy, elevating them into a region of higher energy called the conduction band. As the electrons move to the conduction band, they leave behind "holes" in the valance band. The region between both bands, where no electrons exist, is called the band gap.

Future research will include work to convert heat radiation from a thermal metamaterial to electron-hole pairs in a semiconducting material, a critical step in developing the technology. The thermophotovoltaic technology might be ready for commercialization within seven years, Jacob said.

The United States is pursuing more investigations into Chinese firms with North Korea  sanctions against a Chinese trading company suspected of supporting North Korea's nuclear weapons development.

Daniel Fried, the U.S. State Department's coordinator for sanctions policy, said the investigations are underway during a U.S. Senate hearing on East Asia and the Pacific, Yonhap reported.

"We're investigating. The Treasury and State are investigating firms around the world," Fried said. "There are no limits and there is no administration red line of exempt countries or companies. We go where the evidence takes us." Fried said it is very effective to convey to Chinese banks and companies that trade with North Korean firms under sanctions is dangerous and not worth the trouble, according to the report.

The State Department official also said sanctions measures are not mere slogans. "Our actions on Monday indicate that Chinese companies are not off limits. That news will spread around the Chinese community. We can also use various means to get the word out to Chinese businesses and banks that we are serious," he said.

On Monday the U.S. Treasury announced Hongxiang Industrial, suspected of sending banned material to North Korea, had been placed under unilateral sanctions. Washington is taking action against the company's chief executive Ma Xiaohong, a 44-year-old businesswoman who founded the company in 2000, and three other members of her organization.

Hongxiang Industrial is believed to have exported aluminum oxide, ammonium paratungstate, and tungsten trioxide to North Korea, dual-use items that could have been placed into military use. Aluminum oxide can be used in developing the centrifuges used in uranium enrichment.

Fried also said investigations are underway into Air Koryo, North Korea's commercial airliner.

The Treasury Department and Justice Department took the measures on Monday, saying that the company and the individuals conspired to aid North Korea’s nuclear weapons program in violation of US economic sanctions.

The measures were taken against 44-year-old Ma Xiaohong and her conglomerate based in China's frontier city of Dandong for money laundering and evading sanctions.

The Treasury Department accused the firm, Dandong Hongxiang, and a host of officials of making up a "key illicit network supporting North Korea's weapons proliferation."

Adam J. Szubin, acting undersecretary for terrorism and financial intelligence at the Treasury Department, said, “Treasury will take forceful action to pressure North Korea’s proliferation network and to protect the US financial system from abuse.”

Dandong Hongxiang had over $530 million worth of trade with North Korea from 2011 to 2015, according to a report by the Asian Institute for Policy Studies in Seoul and C4ADS in Washington. The amount could have been enough to help North Korea fund its uranium enrichment facilities, and to design, make, and test its nuclear weapons, the report said.

Among the items traded, there were aluminum ingots, aluminum oxide, ammonium paratungstate and tungsten trioxide as well as materials used in nuclear enrichment centrifuges and missile design.

Tungsten trioxide can be used in making more aerodynamically stable missiles, while aluminum oxide is used to resist corrosion in gas centrifuges during uranium enrichment, according to Asan. It said those could qualify as "potential military and nuclear dual use products" under U.S. Department of Commerce restrictions.

The three other individuals who were targeted include Zhou Jianshu, Hong Jinhua and Luo Chuanxu, who can no longer do business with American individuals or companies. The department also sought to seize 25 bank accounts controlled by Dandong Hongxiang, because it said they "represent property involved in money laundering."

The move came after Pyongyang conducted its fifth nuclear test on September 9. It also tested a submarine-launched ballistic missile in August. South Korean officials say the North is physically ready to conduct its sixth nuclear test.

Pyongyang says it will continue to develop nuclear weapons as a “deterrence” measure against America’s military aggression.

It reported that there is radioisotope container from Daqing Drilling Logging Company get lost during Sep. 19~Sep.21, which is used for the drilling logging.

The municipal government and relevant departments in Songyuan, Jilin took an immediate response on this matter. The provincial and municipal leaders pay much attention to this situation, and have lead departments related to public security, environmental protection and health to take quick steps for searching. Environmental Protection Agency in Songyuan, Jilin sent an expert investigation team to solve that problem.

The lost containers containing radioactive isotope Tin 113 - Indium 113m, its height is 20cm, with a handle, and the logo “2” on the top of the blue tank. The activity is equivalent to class V radioactive sources with very low hazardous sources, but still may cause damage to human body if have been carried properly. If anyone pick up or find that, please don’t deal with it arbitrarily, make sure to contact the environmental protection department for help. The telephone for Songyuan radiation environmental monitoring station is 86 13904383542.

If tungsten material could be used for radioisotope container, then radiation from radioisotope would be absorbed and controlled effectively.

At present, the public security departments are trying hard to find the lost radioisotope container. The relevant departments are under investigation.

Tungsten carbide is a very high hardness materials, cutting tools are mainly used in metal cutting has been widely used. In the machinery industry, mentioned alloy steel or tungsten carbide generally refers to such materials. Carbide cutting tools can be harvested many advantages. Compared to high speed steel cutting tools, in most cases, the use of carbide cutting tools can be harvested only workpiece surface quality is better, but also to obtain higher processing speeds; Carbide Tool can withstand higher cutting heat, which is that it can achieve a higher metal removal rate of the main reasons. When the workpiece machining high-alloy steel or stainless steel such easy processing, or in mass production and capacity expansion of the occasion, a case such as high-speed steel cutting tool wear easily and quickly, using conventional carbide tools can make cutting performance better.

Tungsten carbide cutting tools for metal cutting industrialization began in the nineteen thirties. Since then, it has evolved into carbide by far the most common tool materials. The relatively small size of carbide cutting tools are often made of a whole; only non-solid carbide cutting tools with carbide in the cutting area. Early non-carbide solid carbide tools tend to be welded to the cutter body. To the 1940s, carbide cutting tools manufacturers began producing holding interchangeable machine folder blade cutter, and benefit. Compared to the earlier welding tool, this brain-hole wide open to technological innovation and the use of mechanical clamping structure makes the tool more strength, which has now been recognized as a landmark invention, not only in the field of tool manufacturing further comprising bringing advanced and efficient process for the entire metalworking industry.

The considerable progress in the field of manufacturing opened up vast room for improvement, and immediately increase the carrying capacity of the tool, the tool has the ability to make rapid removal of metal. Replace the blade becomes more simple and cost reductions made to protect the economy, but also makes it possible to separately manufacture cutting module and the cutter body except for the blade failure due to wear or breakage failure. Replace the blades often need to consider the shape, quickly replace the failed cutting edge in several ways, in addition to the blade along the central axis indexing, there are also cases reversed blade front and back. Today, the most recognized industry wide dissemination of "indexable" the title, once also known as: the disposable tip, replaceable blade, replaceable blade.


 

Tungsten carbide indexable insert production technology based on powder metallurgy technology, the production process is as follows: Preparation of carbide mixture, pressing, sintering, sintering treatment step and coating. Despite decades or more basic process remains the same, but at the same time from the progress of science and technology but then blade manufacturing had a significant impact.

Until the 1980s coated carbide grade has not yet appeared. At that time, such that carbide can be common to the processing of different engineering materials, tool manufacturers by adding different additives (such as a hard phase or a metal additive) to the preparation of different carbide grades. Coating technology adoption has greatly promoted the development of the global machinery industry; the vast majority of today are coated carbide grades. This new technology also brings additional benefits, so some special grades can be processed a certain class of materials to be processed. You do not need to add many kinds of cemented carbide substrate additives; This reduces the cemented carbide substrate grades, production process control more stable.

PVD coating in the late 1980s is introduced into the carbide production. PVD coating because at the nanoscale coating areas to overcome the manufacturing of many problems to achieve a breakthrough in the development. PVD coating thus providing a new level of higher wear resistance nano-coating. Compared to conventional PVD coating manner coating as shown by a maximum of 50 nm (nanometer) coating composite, it has been shown to greatly improve the binding strength of the coating.

Tungsten carbide blade production progress technologies from several areas of development. More cutting-edge technology of pressing, sintering technology, coating technology and post-coating technology, more diverse surface treatments can be carried out on the cutting edge of the blade more optimized manufacturing process together make indexable inserts can provide modern metal processing industry to provide more suitable to meet their needs efficient processing solutions.

Tungsten carbide 2016 Shanghai International Expo area of ​​30,000 square meters, is expected to reach more than 500 domestic and foreign exhibitors, professional audience of 30,000 people attended the Shanghai International Expo tungsten carbide is the tungsten carbide areas set product launches, technology exchange and business cooperation in one of the professional event.

1. The establishment of an international brand exhibition, high-tech products, technology, the first to release
Many well-known manufacturers at the show site will publish new equipment, new technology, new materials, allowing you to buy better assessment; open the current Shanghai International Expo Exhibitors List Tungsten carbide, we clearly feel Shanghai International Hard alloy Expo brand cohesion remains unsurpassed: Chinese and Japanese Han Qicheng more than well-known brands, as well as a growing number of overseas famous brand in here, both industry leaders, have extraordinary potential rookie. Include: Kim Shin Zigong, Zhuzhou Lihua, accessible Zhuzhou, Zhuzhou Maoxiang, Zhuzhou Kim Shin, Xiamen Tungsten, Jiujiang spoonbills, Renqiu forward, Shanghai Grand Holcim law, Yueqing source, the Shanghai Research Institute of Materials, Jinan metallurgy Sciences Co., Ltd., Hai Keli special alloy tool and die development Co., Ltd., Taiwan and the United States Yang technology, Xin Matilda, Hunan Dingli technology Co., Ltd., Weihai Wei hard, German PTV, Chen Hao Shanghai composite materials Co., Ltd., Shenyang Heng Jin vacuum Technology Co., Ltd. SGL specialty graphite (Shanghai) Co., Ltd., France Kay Pu Technology Group Shanghai office, Shanghai Oriental carbon Co., Germany Conner KonradFriedrichsTungsten carbide (KFC), Tokai carbon Yao and many other well-known enterprises.

2. "Three Exhibition Linkage" comprehensive interpretation of the metal processing industry chain event
Shanghai International Expo tungsten carbide through continuous upgrading of hardware and software, to optimize the structure of display, in October this year the show will be a new attitude in full bloom, become more popular Tungsten carbide industry event! Tungsten carbide Shanghai International Expo, Shanghai International cutting tools and equipment Exhibition and Shanghai international Exhibition abrasive grinding processing technology exhibition three linkage, will be held in Shanghai World Expo Exhibition October 11.

3. Professional forum the industry heavyweight mystery guest to visit the site
Over the same period will be held 2016CCME finishing Technology Forum and Shanghai International abrasive grinding technology seminars, conferences and adhere to the public nature of dry-based technology, is committed to providing various forms of flexible integration to share trends, the development of Internet technology and the latest developments, assess the latest trends in technology and operations; for technical, research and development personnel, business operators to explore new ideas, look for effective research.

4. 300 domestic and foreign media, broadcast throughout the show dynamic
Shanghai International Expo tungsten carbide and tungsten carbide gathered 300 domestic user industry media reached a strategic cooperation to form a public authority magazines, newspapers, websites, television in one powerful propaganda line-up, with the professional league to reach interactive media, publicity and promotion efforts Show information, to achieve aggregation of dissemination of information, to attract more audiences and downstream industry professionals attending the event, exchange, purchase.

Tungsten carbide 2016CCME Shanghai International Fair will be adhering to the "professionalism, effectiveness, quality, service" four exhibition service standards, more effort to build the field of Tungsten carbide exclusive event.