China Made a Process in High-performance Tungsten Carbide

Chinese R&D team in tungsten carbide has a breakthrough in the research and development of high-performance tungsten carbide composite material, it mainly includes:

1. Phase controlled particle size adjustable nano WC-Co composite powder scale preparation techniques: It takes tungsten-cobalt oxide and carbon as raw material, and uses solid-phase synthesis in-situ reaction to synthesize ultrafine or nano WC-Co composite powder. It has many advantages, such as simple operation, short process, Low-cost equipment, energy saving and so on. The synthesis of composite powder has high purity, low oxygen content, Co content within a wide range of 6-20wt% is accurate and adjustable, which reached on the current international quality ultrafine nano WC-based powder control standards.

2. High liquidity, nano-structure WC-based spraying powder scale preparation techniques: It based on the principle of spray-drying and combines with heat treatment, which not only maintains the characteristics of nano structure, but also can fabricate the thermal spray powder with high fluidity. So it gets to the root of nano powder thermal spraying at high temperature flame flow easily decomposed decarbonization, which is a difficulty in international technical fields.

3. High density, high surface quality and technical preparation of carbide wear and corrosion coating: The technology synergistically adjust the initial powder component, thermal spray granulation and agglomeration process, by a combination of carbon content design, unique heat treatment process, recombinant size, thermal spraying process parameters optimization to fabricate high-performance nano-structure carbide coating. The coating having a porosity of <0.5% of a high density; compared with the conventional micro structure, the surface quality has significantly improved, the surface roughness Ra <0.5m.

4. Ultrafine size nano-crystalline tungsten carbide block preparation: The technology develops a low-temperature region slow heating rate, low pressure, high temperature rapid heating region segmentation, greater pressure, does not heat the unique field effect sintering process. And produces nano tungsten carbide block with average grain size of 60-100nm. The average grain size of 60nm dense nano-crystalline alloy is the smallest grain size reported so far around the world. Meanwhile, nano-crystalline tungsten carbide sintered material can meet the requirements of high hardness and high fracture toughness.

China Has a Breakthrough in High-performance Tungsten Carbide

China tungsten carbide industry has 60 years of development history, which has been regarded as a big country of carbide. According to carbide branch of CTIA (China Tungsten Industry Association) statistics, the last three years (2012-2014) of the annual output of domestic carbide 2.2-2.5 million tons, which more than 40% of global output. Although the production and consumption of tungsten carbide of our country is at the leading place around the world, as far as the level of manufacture and technology, we still fall behind. In terms of the plateau of domestic tungsten carbide industries development, we developed many research projects and establish a special carbide R&D team, after more than ten years of basic research and technology development to study ultra-fine carbide nano-scale manufacturing equipment and engineering application of a series of new technologies, and work closely with companies to develop over carbide materials and high value-added products toward high-end applications development.

For WC-based tungsten carbide, compared with conventional coarse grain (the average grain size about 13μm), tungsten carbide with ultrafine grain (the average grain size about 200-500nm) and nano grain (the average grain size lower than 200nm) has high hardness, high strength, high fracture strength and excellent wear and corrosion resistance, which becomes the indispensable material for drilling, cutting and milling process. Since late 1990s, nano tungsten carbide has been emerged many new processes. In recent years, ultra-fine carbide and nano-scale preparation and industrial applications become international attention, reflecting the forefront of competitive research focus, which experienced a period of many preparation methods of nano carbide change of evolution. Such as sol - gel / co-precipitation method, a plasma method, but they are limited to use in nano WC powder synthetise in laboratory; spark plasma sintering, high pressure and so consolidation is limited to the preparation laboratory simple shape and small three-dimensional nano-polycrystalline material; Complex spray conversion method steps, the high cost of the process, demanding precision control, which greatly limits the technology in the manufacture of nano-WC-based powder application.

high-performance tungsten carbide mills

 

Tungsten Trioxide - Graphene Photocatalyst, Nemesis of Dye Pollutant

Not long ago, a kind of tungsten trioxide - graphene photocatalyst has been developed; this catalyst can degrade the dye Rhodamine B almost completely in 15 minutes. This is much faster than the degradation times that the single ingredient of tungsten trioxide or titanium dioxide photocatalyst can be achieved. This kind of photocatalyst is jointly discovered by Chinese and American scientists, and also, they imagined that this enormous potential invention shall be used in the visible light degradation of dye pollutant.

tungsten-trioxide-and-graphene
 
Because of the porous structure and special composition, the discovered tungsten trioxide - graphene photocatalyst has shown an excellent performance. The tungsten trioxide nano-framework can efficiently absorb the visible light due to multiple reflections in the pores. Also, the generated charges will quickly transfer to the graphene, thus to avoid the charge recombination. In addition, graphene nanosheets exposed on the surface of the photocatalyst, which guarantees the π-π contamination between graphene and dye pollutant, and thus lead to high absorption rate of catalyst material on the substrate. These combined features enhance the degradation of dye pollutants by the photocatalysis.
 
Tungsten trioxide is a transition metal oxide, which is widely used in gas sensors, photocatalysts, electrochromic device and so on, due to its special physical and chemical properties, and has a relatively broad application prospects. As a semiconductor photocatalyst, tungsten trioxide can produce holes with the strong oxidizing power and hydroxyl radicals in the reaction, and thus can be used to degrade pollutants in water. The researchers believed that, this very potential tungsten trioxide - graphene composite photocatalyst will have a widely concern, in the challenge of environmental remediation, and also will become the nemesis of dye pollutants; moreover, they highlight that this material is prepared by electrospinning method, which is suitable for industrial scale production.

 

Minmetals Published Tungsten Market Guide Price

Ganzhou Tungsten Industry Association yesterday announced the March 2016 market forecast average price of tungsten: tungsten concentrate 75,000 RMB/ton, APT 105,000.00 RMB/ton, middle size tungsten powder 168 RMB/kg. Compared to February, the price of tungsten concentrates unchanged, but APT raised 2,000 RMB for each ton and the middle size of tungsten powder raised 4 RMB for each kg. This showed Ganzhou Tungsten Industry Association has optimistic attitude about the spring tungsten market.

tungsten concentrate

Following Minmetals tungsten market guide price published in May, now re-released new tungsten market guidance in June, including tungsten concentrate 75,000/ton, scheelite 74,000/ton. Compared with the May guidance, the chain relative ratio were down 3,000 for each ton. And difference with May, this time Minmetals guide price of tungsten concentrate is similar to Ganzhou Tungsten Association tungsten concentrate forecast average price. Minmetals tungsten market guide price can be slightly higher than recent market transaction price, also showed Minmetals willingness to stabilize tungsten market.

The manufacturers of raw materials has optimistic attitude about tungsten market, so they reluctant to sale raw material and want to increase the price, but affected by low tungsten finished products demand the price acceptance is low and the turnover is limited. But supported by supply-side reform, mainly China domestic mining enterprises to suspend shipments, based on the policy is expected to continue to bring some benefit, so in the short-term the price of tungsten is difficult to fall down and will slight increase. 65% tungsten concentrate purchase price is not less than 75,000 RMB/ton and APT purchase price is not less than 115,000.00 RMB/ton. Besides, the market is still upside.

China's economic is gradually recovery, but tungsten finished products industry demand is shrinking, and the industry has been going on downturn for a long time. The end of January this year, eight large tungsten enterprises of China met in Chaozhou decided in 2016 tungsten concentrate reduction of output more than 15%. Reduced supply is good for industry rebound.

Foreign Carbide Circular Blade Industry Focus on Brand Building

Tungsten carbide circular blade is a kind of super-hard composite material that mainly composed of refractory metal compound and the binder metal fabricated by PM (Powder Metallurgy). Due to it has many advantages, such as high hardness, high strength, excellent wear and corrosion resistance and is able to keep better performance at high temperature, etc, which becomes indispensable in cutting tool materials. Its appearance was circular, with a hole in the middle for easy fixing, generally used for the equipment cutting, trimming and other operations. According to the shape of the circular blade, it can be specifically divided into flat edge, sharp edge, and irregular edge. Conventional carbide circular blade size diameter φ300-1000mm, thickness 0.5-300mm, common in many industries slitting blades, such as paper making, paper products processing, adhesive tape products, films, wire and cable, rubber, aluminum, chemical fiber , non-manufacturing cloth, composite packaging materials, telecommunications appliances, cigarettes, leather, printing, food, clothing and other industries.

Since tungsten carbide circular blade has many advantages, domestic enterprises also works on that. However, They stressed by low prices, the price war to attract customers, which to some extent led to the cutting tool market vicious competition, low prices can not guarantee the quality of products, but ultimately customers on the domestic carbide circular blade lose confidence, a huge loss of customers caused. Take automobile industry as an example, it has higher requirements on the efficiency and service life of cutting tools. In order to avoid change blades cause the entire production line shut down and causing huge economic losses, usually mandatory unified tool change mode, if the blade quality problems, will affect the entire batch of products. By comparison, foreign tungsten carbide circular blade industries more focus on the brand building, and set the quality and the requirements of customers as first place, which build good foundation for the developments. In aerospace, military aspects of the field of production parts, molds and some large turbines, steam turbines, generators, and its not only high precision machining, material is also difficult to process (such as high temperature alloys, nickel-titanium alloy), high-quality carbide circular blade can perfectly meet the needs.

tungsten carbide circular blade

 

Tungsten Trioxide Denitration Catalyst Regeneration Technology

Recently, the State Environmental Protection Bureau delegation went to Jiangsu, Shanghai investigagion selective catalytic reduction denitration catalyst recycling and subsequent disposal. The study is mainly to promote the selective catalytic reduction denitration resource utilization and safe disposal of the catalyst after elimination, rational planning its whereabouts, thus to reduce the running cost of environmental protection, resolve the environmental issues.

tungsten trioxide and denitration system
 
Denitration system has already become an important part of coal-fired power plant, wherein the tungsten trioxide denitration catalyst is the core part of SCR system which takes the higher proportion of total investment. Currently, the denitration catalyst commonly used in the market are based on titanium dioxide as the carrier, vanadium pentoxide as the main active ingredient, tungsten trioxide (and / or molybdenum trioxide) as the anti-oxidant, anti-sulfide, anti-toxic auxiliary component. Theoretically, as the catalyst, it doesn’t as a reactant and cannot be consumed, so its effect is supposed to be permanent. However, in China, the catalyst market is now really staying in a relatively chaotic situation; usually, the catalyst will be deactivation after about three years. The main reasons which cause catalyst deactivation are sintering, poisoning, intoxication, calcium, alkali metal poisoning, and poisoning of sulfur trioxide, and the voids plug fouling of catalyst, ect..
 
The regeneration or replacement of denitration catalyst will directly affect the running costs of the SCR system, therefore, the research on SCR catalyst deactivation and regeneration has an important practical significance. In practical applications, the regeneration techniques of failure tungsten trioxide denitration catalyst are generally the two kinds of live regeneration and plant regeneration. Since the site regeneration will pollute the around environment and water quality of the plant, also the quality and performance of catalyst which regenerated in the site are poor, and therefore, plant regeneration is the development direction. SCR catalyst is impregnated plant regeneration during a series of cleaning, ash removal, ultrasonic treatment, the active ingredient (vanadium, tungsten, molybdenum, etc.), and finally achieve the goal of restoring catalyst activity.

 

Tungsten Trioxide Denitration Catalyst Creates a Myth of Clean Diesel Technology

Recently, a report said Volkswagen had altered diesel engines to beat emissions tests, which immediately caused the great anger of the consumers. The agency reported that some diesel powered vehicles made by Volkswagen and its subsidiaries Audi and Porsche contained software which can lower the emissions during tests; however, during the normal driving, the software has gone. On the discharge gate event, Mullen, the CEO of Volkswagen expressed they had especially tough to come through the past few months. On the road, the emissions of some vehicles can even reach up to 40 times as much NOx—a combination of nitric oxide and nitrogen dioxide—as allowed, which has caused enormous pressure on the environment protection.

Volkswagen CEO Murren denitration catalyst
 
In the atmosphere, nitrogen dioxide contributes to the formation of ground-level ozone and particulate matter, which create further negative health effects. A recent study estimated that the excess NOx can cause the additional unexpected deaths and damages compared with the regular emissions. In Europe, however, the excess NOx from the altered cars may have little impact, which shows the high NOx emissions have already upset the region, because it has weaker emissions regulations and more diesel powered cars. So the issue of balancing the NOx emissions control with fuel efficiency is a tough nut to crack.
 
In addition, the exhaust of diesel powered vehicles contains a lot of sulfur, which not only causes air pollution, but also causes the poisoning of the denitration catalyst for automotive exhaust gas, and influence the effect of exhaust treatment. Tungsten trioxide denitration catalyst makes the clean diesel technology not a myth. Since tungsten trioxide can improve the sulfidation resistance of the catalyst, it is widely used in the denitration catalyst. In addition, tungsten trioxide can also broaden the operating temperature of the catalyst, and make it suitable for the denitration catalyst under lean burn conditions; therefore, the denitration catalyst which contains tungsten trioxide has very broad prospect in the clean fuel technologies.

 

Defects of Large Tungsten Carbide Products in China

Theoretically, tungsten carbide is a kind of super-hard material that consists of refractory metal carbides and binder phase metal and manufactured by PM (Powder Metallurgy). And at the time of cemented carbide industry has just started, most of which are made of tungsten carbide WC and cobalt Co composition, referred to as tungsten carbide cobalt. Since WC-Co has simple structure, high hardness and excellent wear and corrosion resistance, it can be widely used in cutting, drilling, molding and other industries. Besides, tungsten carbide also includes WC-TiC-Co carbides, WC-TiC / TaC / NbC-Co carbides, steel bonded carbides and so on. Common tungsten carbide grades are YG3, YG6, YG8, YG10, YG12, YG15, YG20, YT15, etc, each grade due to the different ratio of WC and Co, with different performance advantages, some suitable for semi-finishing of non-ferrous metals and alloys, some iron alloy suitable for high-speed milling, some suitable for steel forgings, stampings and castings the surface finish.

Although tungsten carbide plays an important role in cutting tools, drilling tools and molding materials because of the excellent wear resistance and toughness, compared with higher hardness of diamond products, it has begun to face the danger of being substituted in some applications. Diamond is a mineral composed of pure carbon, which is the hardest substance in nature. There is little diamond in nature, so people through high temperature and pressure to convert the carbon into diamond nowadays. This synthetic diamond has higher hardness and better performance in strength, nearly a decade of development in our country very rapidly, particularly in some of the cutting tools and handicraft industries are becoming more common. In addition, diamond is also known as super-abrasive in stone, construction, industrial processing, aerospace, electronics, precision measuring instruments and other fields. Currently, due to the rapid development of the diamond industry, it is growing at a high speed to produce a lot of new diamond tools, some far more than conventional carbide tools in performance. Especially domestic priority level of technology and equipment, mainly in small and medium sized carbide rod and plate-based, there some defects in the large carbide products, which is the focus of the future is the development of domestic carbide industry.

tungsten carbide products

 

Technological Innovation of Shizhuyuan Promotes Development of Tungsten Heater

Recently, the school enterprise cooperation project team of multi metal concentrator of Hunan Shizhuyuan Nonferrous Metals Co., Ltd. and Central South University transform the process flow of tungsten mineral processing, primarily through technological innovation and other means to improve the grade of tungsten concentrates and the recovery rate of tungsten. Reversing the downturn situation of tungsten industry recently. Multi metal concentrator of Hunan Shizhuyuan began to flotation separation test at the end of 2014, using the original wolframite slime idle flotation device. After testing more than five months, recovery and grade of tungsten have been greatly improved, this can be applied in practical production.

After getting good results, this plant promote technology to 2000 tons / day workshop tungsten roughing in August 2015, after technicians careful debugging for a period, the whole plant rougher tungsten segment has a stable milling of ores indicators. In order to further improve the efficiency of new technology tungsten beneficiation experiments, the technicians began a 24-hour spell line system from 2016, monitoring the experimental dynamic of index in real time. As a raw material of tungsten heater, constantly improve the beneficiation process of tungsten can not only improve the quality of products, but also ensure that supply number.

The development of innovative technology also improves the recovery rate, so that resources can be repeated used, which is good for the protection of the environment and greatly reduce production costs. The successful case of this plant plays a leading role on chinese tungsten industry, which is a revolutionary breakthrough in the field of mineral processing of tungsten, and promotes the development of related industries. In the fierce market competition, enterprises are facing a number of random changes. Enterprises can inspire the original and potential innovation vitality only to make innovations constantly that can brings abundant profit.

Shizhuyuan and tungsten heater

 

Discovery of Tungsten Ore Improves the Yield of Tungsten Heater

According to the China Nonferrous Metals Industry Network reported that Jiangxi Nonferrous Metals Geological Exploration Bureau discovered new tungsten ore bodies. After four years of mineral geological survey, the project "Xiushui County, Jiangxi Province Wanghuojian Tungsten Ore Census" of Jiangxi Nonferrous Metals Geological Exploration Bureau was checked and accepted by expert group with a good level. Through efforts from all sides, the Exploration Bureau discovered new tungsten ore and gold ore bodies. The expert group has carefully listened to the report of results of the project.

This is another important discovery after worldwide scale tungsten ore was found in Jiangxi in 2014. This major discovery makes the tungsten resources in Jiangxi form the new pattern "Three Pillars", which consists of southern Jiangxi, northern Jiangxi, and northwestern Jiangxi. It further established the position of "World Tungsten" of Jiangxi, improving the level of protection of tungsten ore resources, consolidating the discourse power of tungsten ore for China in the world. Therefore, this discovery plays a significance role on tungsten reserves and development. Analysts believe that, A-share listed companies, Chongyi Zhangyuan Tungsten Co.,Ltd, Jiangxi Copper Corporation, Xiamen Tungsten Co.,Ltd and other relevant local companies are expected to directly benefit from it.

Tungsten and its alloys is one of important functional materials for the modern industrial, defense and high-tech applications, which are widely used in aerospace, atomic energy, shipbuilding, automotive industry, electrical industry, electronic industry, chemical industry and many other areas. China, as one of the world's largest tungsten resources reserves countries, due to irrational exploitation of rare earth, and tungsten belongs to non-renewable resources, therefore, currently it is exhausted. And new discovery of the tungsten ore in Jiangxi, will improve the situation of tungsten resources to some extent. Tungsten is important raw material for tungsten heater and other tungsten products, so tungsten ore discovery will greatly promote the mass production of tungsten related products.

tunsgten ore and tungsten heater

 

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