Tungsten Alloy | Strategic Rare Metal

Known as “industrial teeth”, tungsten is an important strategic rare metal, its content in the earth’s crust is only 0.007%, and it is the basic raw material of modern industry. Since it was discovered by scientists in 1783, it has a history of more than 200 years. Tungsten has excellent characteristics such as large specificity, high melting point, high hardness, good thermal and electrical conductivity, heat resistance, wear resistance, corrosion resistance, stable chemical properties, etc. It is widely used in today’s high-tech products and people’s daily life. It plays a very important role in the development of the national economy, so people also regard tungsten as an important strategic metal.

The chemical element symbol W of tungsten is a silvery-white, lustrous metal with a body-centered cubic structure, which looks like steel. The melting point of tungsten is 3410°C, which is one of the metals with the highest melting point in nature. It has high hardness, high density and good high temperature strength. The chemical properties are stable, and a passive film will be formed on the surface at room temperature, which is not easily corroded by acid, alkali and aqua regia. At present, more than 20 kinds of tungsten ores have been discovered in the world, but there are only two kinds of industrial significance – wolframite and scheelite.

The main products of the tungsten industry include tungsten concentrate, ammonium paratungstate (APT), tungsten oxide, tungsten powder, tungsten carbide machining powder and tungsten materials. Tungsten products are widely used in machinery manufacturing, iron and steel industry, aerospace and information industry and other fields, and are irreplaceable basic data and strategic resources of the national economy. Tungsten is the most important alloying element. Tungsten-added cemented carbide has high hardness and wear resistance. It is used to manufacture cutting tools, knives, drilling tools and wear-resistant parts. It is known as “industrial teeth”.

In alloy manufacturing, tungsten is mainly used to improve the properties of alloy materials, increase hardness, high temperature resistance and wear resistance, so tungsten is also called “industrial salt”. No direct substitutes have been found in most of its application areas. There have been studies in the United States that in the field of high-speed steel, molybdenum can be used to replace tungsten to improve corrosion resistance, increase high-temperature strength and improve weldability. However, tungsten-molybdenum alloys are often used in industrial production, that is, both are added to the alloy, and the method of directly replacing tungsten with molybdenum is not yet feasible. Due to the different properties of the two, there are still differences in hardness and high-temperature strength between the high-speed steel products added with molybdenum and the products added with tungsten, and the development of modern industry has higher and higher requirements for material performance, and low-performance substitutes cannot meet the market requirements. need. Therefore, in the field of application of tungsten, it can be considered that there is no effective direct substitute.

Tungsten consumption

Europe, the United States, Japan, the Commonwealth of Independent States and China are the major tungsten consumers in the world today. Divided according to the end use of tungsten, cemented carbide is the largest consumption area, accounting for more than half of the total consumption of tungsten, followed by steel and alloys, rolled products and chemical and other products. The amount of tungsten in these products is Japan About 50%, Europe and the United States are higher than 60%, while the consumption of steel containing tungsten is 25% in Europe and higher than 30% in Japan.

Tungsten Research

Tungsten alloy has comprehensive properties such as high melting point, high density, high strength, low thermal expansion coefficient, corrosion resistance and good machining, and is widely used in aerospace, military equipment, electronics, chemical industry and many other fields, including:

• ① use Carbide used in cutting, welding and spraying, such as tungsten carbide.
• ②Used in a large number of filaments and cathodes of electron tubes in the electronics industry, shock-resistant tungsten wires, composite rare earth tungsten electrodes, etc.
• ③Used in high temperature fields.

Such as heating elements of high-temperature resistance furnaces and armor-piercing bullets, tungsten bullets, and drug-shaped covers made in the military. In order to improve the plasticity of tungsten alloy material and reduce its plastic-brittle transition temperature. Further improving its high-temperature thermal strength properties has always been a persistent research hotspot in the field of tungsten alloys. Therefore, the main content of the research and development of tungsten alloys is the plastic-brittle transition behavior of materials, high-temperature strength characteristics, welding and compounding, and the optimization of the preparation process, that is to say, refinement, strengthening and compounding have been mentioned. Agenda comes up.

Purification research

It refers to the research on the purification of refractory metals and the purification degree of the environment during processing, which plays a very important role in improving the plasticity of tungsten materials and reducing their plastic-brittle transition temperature, because harmful impurities such as oxygen and nitrogen will lead to plastic-brittle transition temperature Significantly improved, increasing the brittleness of the material and making it difficult to process. The purification of tungsten in my country mostly starts from the purification of oxides, and the chemical purity of APT is improved through solvent extraction, ion exchange and multiple recrystallization processes. High-purity refractory metals and single crystals required by modern VLSI technology are prepared with high-purity powders. Northwest Institute of Nonferrous Metals is the main research and development unit of high-purity refractory metals and single crystal materials in my country. The purity of its products has reached more than four nines, and it can provide high-purity tungsten machining materials and single crystals of various specifications.

Detailed study

It mainly revolves around powder refinement content. On the basis of relying on our own research and combining the introduction and digestion of foreign technology, my country has expanded the production scale of submicron powder and ultrafine powder, because the production of cemented carbide with ultrafine grain structure can reduce the sintering temperature of tungsten billet and obtain fine This type of powder is required for the billets of the grain structure. In recent years, my country has also carried out research on nano-tungsten powder and the exploration of preparing 2 8 ’ alloy and hard alloy with nano-tungsten powder.

Strengthening Research

Strengthening and toughening research aims to improve the heat-resistant strength and toughness of refractory metal materials. Over the years, Baoji Refractory Metal Materials Co., Ltd., Northwest Nonferrous Metal Research Institute, Beijing Iron and Steel Research Institute, and Central South University have conducted major research on the selection of doping conditions, the reduction of doped blue tungsten, and the control of powder particle size and distribution. There are two types of reinforcement: single reinforcement (using one enhancer) and compound reinforcement (using two or more enhancers).

Composite research

Our country has produced many composite materials through composite research, such as W-Cu, W-Ag, Mo-Cu, Mo-Ag and other “pseudo-alloys”, which have been widely used in electric power, electronics and defense departments. In recent years, my country has developed W-Mo, W-RE composite rotating anode targets, W-Mo, W-Ir composite nozzles, which are used in medical equipment, ceramic fiber industry and other departments. The current situation of the compounding of tungsten and molybdenum materials in my country is shown in the table.

The application of tungsten in China can be roughly divided into four categories:

• 1. Carbide used in cutting, wear-resistant, welding and spraying. Tungsten carbide is widely used in the mining and petroleum industries, mainly for drill bits, bulldozer blades and crushing machinery. Tungsten carbide is also widely used in wear parts of transportation and electrical equipment.
• 2. Used in electrical and electronic industries. In the electronics industry, the filaments of a large number of electric lamps and the cathodes of electronic tubes, the electrical contacts of automobiles, the heating elements of high-temperature resistance furnaces, the counterweights and pendulums used in the aerospace industry, etc., all come from the processing and production of tungsten.
• 3. Used in high-speed steel, tool steel, die steel, high-temperature high-strength alloy and various non-ferrous metal alloys. Tungsten alloys formed by adding other metals are widely used in high-temperature fields, and even military armor-piercing bullets.
• 4. Used in various chemical products. Tungsten is widely used in light industry fields such as textile dyes, paint pigments, ceramic glazes, toners and glass coloring. Tungsten compounds are used as fluorescent materials for TV picture tubes, X-ray fluorescent screens and fluorescent lamps. Sodium tungstate is used as a corrosion inhibitor and fire retardant in the textile industry. Used in the manufacture of petroleum refining coal. In short, the main uses of tungsten and tungsten alloys are shown in the table.

The world’s tungsten reserves are scarce, and China has a resource advantage

Tungsten is a very scarce non-ferrous metal resource. According to the data of the US Geological Survey, as of 2011, the total proven reserves of tungsten in the world were only 3.1 million tons, and the basic reserves were 6.185 million tons. Most tungsten resources are distributed in relatively young mountain belts, represented by the Alps-Himalayas and the Pacific Rim geological belt. These two regions concentrate most of the large-scale high-quality tungsten resources in the world.

From a national perspective, according to the data of the US Geological Survey in 2011, tungsten resources are mainly concentrated in China, Canada, Russia, the United States and Bolivia. The five countries together account for 84.93% of the world’s total reserves and 84.52% of the reserve base. At present, China has proven reserves of 1.9 million tons of tungsten ore, accounting for more than 65% of the world’s total proven reserves, and its basic reserves are close to 70% of the global resource reserves. It has an absolute resource advantage.

China’s tungsten resources are concentrated in South China

China’s proven tungsten resources are widely distributed in 22 provinces, municipalities and autonomous regions, but the reserves are mainly concentrated in South China. Among them, Hunan and Jiangxi are the most prominent, accounting for 39% and 27% of the country’s proven reserves respectively, followed by Henan and Fujian, and the combined reserves of the four provinces account for 90% of the country’s total reserves.

Ganzhou City, China is very rich in tungsten resources, and is known as the “tungsten capital of the world”. 70% of similar mines in the country and 60% of the world; tungsten ore production accounts for about 20-30% of the country, and it is the main production area of ​​tungsten in my country and even in the world.

In terms of new tungsten ore exploration, in June 2012 there was good news in northern Jiangxi. The proven reserves of Dahutang Tungsten Mine in Wuning County, Jiujiang City have reached 1.06 million tons, far exceeding the original reserved reserves of Jiangxi tungsten resources. It is expected to become the world’s largest tungsten mine with the largest proven reserves. The value exceeds 300 billion yuan. The amount of tungsten ore deposits is yet to be filed with relevant departments, so the precise amount of ore deposits has not yet been announced. According to the information fed back by the 916 geological team of the exploration party, the prospects for prospecting in the Dahutang mining area and its surrounding areas are bright, and it is entirely possible to discover large tungsten deposits again.

The discovery of the Dahutang tungsten mine undoubtedly makes the strategic position of China’s tungsten resources more obvious. If calculated on the basis of 1.06 million tons of proven reserves, the current proven reserves of China’s tungsten resources will reach 74.7% of the world’s total proven reserves, and the resource monopoly advantage is even greater.

South China’s tungsten resources are concentrated in large-scale advantageous enterprises

With the emphasis on the strategic significance of resources, the price of mineral resources continues to rise. Obtaining resource advantages has become the key to the survival and development of mining enterprises, and the rise in resource prices has also led to the intensification of over-exploitation. In recent years, driven by the will of the government, tungsten resources are rapidly concentrated in large-scale advantageous enterprises, especially represented by China Minmetals Group.

At present, Minmetals Group controls many tungsten resource developers such as Jiangxi Tungsten Industry Group and Hunan Nonferrous Metals Group, and also participates in several non-ferrous metal listed companies. Through related relationships, Minmetals owns the exploration rights of many large tungsten mines in China. As of the end of 2010, it has a total of 2.165 million tons of tungsten resources and 618,000 tons of recoverable reserves. It is the resource leader in China’s tungsten industry.

Problems facing the tungsten industry

Since the beginning of the 20th century, people have never stopped developing and applying tungsten and its products. The demand for tungsten products in human society is increasing day by day, and the tungsten industry has gradually become one of the backbone industries leading social progress. However, my country’s scarce strategic resources are currently facing a crisis of depletion. How to hold on to the advantages of tungsten resources, regain pricing power from foreign companies, rational and orderly mining, strengthen technological innovation in deep processing, and transform the industrial structure appear to be an imperative must do.

China’s tungsten industry development status, existing problems and gaps

In the field of tungsten industry research and development, my country has established a number of national key laboratories in recent years (such as Zhuzhou Cemented Carbide Company was approved to establish the first enterprise cemented carbide state key laboratory), national engineering research centers and state-level enterprises Technology Center, and established a number of provincial and ministerial key laboratories and engineering research centers. In particular, national science and technology programs such as the “863 Program”, “Science and Technology Support Program” and “Major Equipment Manufacturing” have established projects to vigorously support the research and development of major key technologies in the tungsten and cemented carbide industries. Domestic universities, scientific research institutes and enterprises have achieved a number of landmark achievements of my country’s independent intellectual property rights in the research and development of tungsten and cemented carbide, such as: rare earth tungsten electrode preparation technology, scheelite and black and white tungsten mixture. technology, ultrafine/nano W powder and WC powder, WC—Co ultrafine/nano composite powder synthesis technology, ultrafine-grained hard alloy, gradient hard alloy preparation technology, integrated manufacturing technology of coated hard alloy cutting tools, etc.

Judging from the development of my country’s tungsten industry in recent years, there are currently more than 400 enterprises engaged in tungsten mining, tungsten smelting and tungsten deep processing, with more than 100,000 employees in the industry. In order to gradually expand the market share and influence of their products in the country and the world, more and more large and medium-sized tungsten enterprises realize that it is urgent to adjust the industrial structure. However, it is not optimistic that my country has not yet formed the economic advantages and international competitiveness of the tungsten and cemented carbide industries, especially in the field of tungsten deep processing. Wire, tungsten materials and other aspects still have a big gap with the international advanced level. At present, the key problem restricting the high-end development of my country’s tungsten industry is the lack of core technology and high value-added products. The main problems and gaps are manifested in the following aspects: resource consumption and environmental impact; product quality, structure and added value; industrial structure, scale and competitiveness; technology and talent support capabilities; industrial policy, system and mechanism issues .

Resource consumption and environmental impact

One is worrying about total mining control. Many mines have been over-exploited, which greatly shortens their mining life. If they develop at such a speed, based on my country’s tungsten resource reserves, they can only last for more than 30 years, which is far below the world average. On the other hand, due to the lack of reasonable export control, the mined tungsten products are often sold abroad at extremely low prices. However, countries with large tungsten resources such as the United States have stopped mining tungsten resources and completely rely on imports.

Second, the comprehensive utilization rate of tungsten resources is low, especially in terms of tungsten mining and china cnc machining technology and resource comprehensive utilization rate, there is still a big gap compared with foreign developed regions. Insufficient mining recovery rate and excess smelting capacity are the direct factors leading to this problem. The mining recovery rate of tungsten enterprises in my country is about 50%, and some small enterprises even do not exceed 30%. At the same time, the production lines of APT (ammonium paratungstate), tungsten powder, and ferro-tungsten are seriously duplicated, resulting in serious overcapacity.

Third, the recycling rate of secondary tungsten resources is low. The tungsten content of waste cemented carbide can reach 40% to 95%, which is much higher than the tungsten content of APT, the raw material for cemented carbide production. It has very high utilization value, but due to factors such as cost, output, purity and environment Restrictions make the utilization rate of secondary tungsten resources low.

Fourth, during the metallurgical processing of tungsten, no attention has been paid to the effective protection of the environment. The resulting “three wastes” will have a devastating blow to the local environment. This practice of reckless and immediate interests must be changed immediately .

Quality, structure and added value of tungsten products

• First, the product quality control technology has a large gap compared with foreign countries. At present, the development of the international tungsten industry is facing the direction of high-precision tungsten deep-processing products of purification, refinement, strengthening and compounding. The quality of various foreign tungsten products is better than domestic ones, impurity elements can be reduced to μg/g (for example, Germany can produce tungsten with a purity of 6N, which is used in the electronics industry), and the particle size and composition are controllable and stable.
• Second, technological development has played an important role in improving product quality, optimizing product structure, and increasing added value. The integrated technology of material selection and metallurgy developed in recent years has important development potential and is expected to play an important role in the development of high-end tungsten products. However, our country is still our shortcoming in cemented carbide, and some key core intellectual property rights are still occupied by foreign companies, which is extremely unfavorable to my country’s tungsten deep-processing enterprises.
• Third, the proportion of tungsten products with high added value in exports is obviously low. At present, my country is entering a high-speed period of economic growth. Since domestic tungsten products are difficult to meet high-end demand, it is necessary to import a large number of high-end tungsten products from abroad every year, and the import price is high. At the same time, the tungsten products we export every year are less than imported Half of the price is sold overseas, and the situation is very embarrassing.

Industrial structure, scale and competitiveness

First, no industrial clusters have been formed. my country’s tungsten enterprises cover the entire tungsten industry chain from upstream to downstream, from mining to smelting, and even intermediate products and applications. Due to the lack of an effective access management system, most of the enterprises have small production scales, low production automation, and product innovation. Seriously insufficient capacity, lack of strong international competitiveness.

Second, the number of core independent intellectual property rights owned by enterprises is very small, especially in the research and development of cemented carbide. Most enterprises despise research and development, and invest even less than 1% of their sales revenue, which has become the direct cause of this situation.

Third, the construction of enterprise technical quality standards lags behind. Applied research on the performance and use effects of tungsten and cemented carbide products is relatively weak, and the construction of enterprise technical quality standards is lagging behind. In addition, the performance evaluation methods used in China are seriously outdated, and many companies are still using the static evaluation methods decades ago, which cannot objectively, truly and comprehensively reflect the performance of the product, cannot reliably predict the use effect of the product, and cannot accurately guide users Selection and use of tungsten and carbide machining products.

Technology and Talent Support Capabilities

At present, there are very few scientific research units that take the development of tungsten and cemented carbide as the main research and development direction, and the research and development personnel are also relatively scarce, resulting in low innovation capabilities, especially for some production-oriented enterprises that focus on simple processing, and their technical research capabilities are weak. At the same time, some research and applications have not been effectively transformed, which greatly restricts the ability of my country’s tungsten products to innovate, not to mention some high-end and high value-added products.

Industrial policy, system and mechanism issues

It is mainly reflected in the fact that the containment of tungsten smelting and primary product production capacity is not enough; quota allocation should be more inclined to high-quality, high value-added, high-profit products and enterprises, and guide enterprises to high-end development; Recycling is not given enough attention, and relevant policies, regulations and incentives are not in place; it is necessary to encourage enterprises to increase their own research and development investment and promote the transformation of scientific and technological achievements in schools, etc., to guide enterprises to embark on a scientific and technological innovation path that combines production, learning and research.

Development direction and countermeasures of my country’s tungsten industry

• First of all, for the development of the tungsten industry, we should attach great importance to basic research and technological innovation from the source, which is of great significance to the high value-added utilization and sustainable development of tungsten resources.
• Secondly, tungsten product manufacturers must adapt to changes in the situation, closely integrate production, education and research, strengthen technological innovation, reform the industrial structure, and develop high-tech and high value-added products in order to win in international competition; Under the guidance of the concept of recycling and recycling, we will develop low-consumption, low-emission, high-efficiency extraction and deep processing technologies for my country’s tungsten secondary resources.
• Third, it is urgent to improve the design and manufacturing capabilities of cemented carbide deep-processing products. It is recommended to make breakthroughs in the following aspects: (1) Obtain independent intellectual property rights of WC-based nano-powder products and thermal spraying materials, and change the status quo of relying on imports. (2) Improve the performance and lifespan of the hard alloy protective coating, and gradually meet the international level. (3) Nanocrystalline cemented carbide sintering technology has been industrialized, and products have been applied in high-end applications.
• Fourth, gradually establish a reasonable and standardized cemented carbide comprehensive utilization technology to truly achieve low energy consumption, high quality, and high output without causing damage to the environment and achieve sustainable development.