China has a vast land and many treasures, which provide key rare metal elements for modern industry. Even if some rare metals are temporarily undiscovered or have small reserves, we can always find them, such as rhenium, a key element in aero engines.
Recently, we have discovered not only rhenium ore in Shaanxi, but also associated rhenium ore in the Zhanling molybdenum deposit in Anhui Province, which is the envy of other countries.
Since ancient times, mankind's exploration of the unknown world has never ended. In 1869, the Russian scientist Dateleleev revealed the "periodic table", which he believed contained elements that had not yet been recognized by humans.
In 1913, the British genius physicist Henry Moselley proposed the concept of atomic number and estimated that at least four elements had not yet been discovered, including element 75.
In May 1925, after three years of hard work, the Nodaks successfully extracted 2 milligrams of element 75 in the laboratory, and named it "rhenium" inspired by the Rhine River, which was the last stable element discovered by mankind.
Rhenium is a silvery-white rare metal with extremely limited reserves in the earth's crust, accounting for only a very small percentage of the earth. According to statistics, the world's proven rhenium reserves are about 2,500 tons, of which the Western Hemisphere accounts for 75% of the world, Chile ranks first in the world with 1,300 tons of reserves, the United States ranks second with 390 tons of reserves, and Russia ranks third with 310 tons of reserves.
China's large-scale rhenium mine was only discovered around 2010, located in the Huanglongpu molybdenum mine area of Luonan County, Shaanxi Province, with reserves of about 176 tons, which is the largest rhenium mine in China.
In 2017, associated rhenium ore was discovered in the Zhanling molybdenum deposit in Jing County, Anhui Province, with reserves of about 30 tons and good development conditions. Although China's rhenium reserves account for only about 2% of the world's total, the proven reserves have broken the monopoly of the United States and other Western countries.
However, for a long time after the discovery of rhenium, it was not used effectively and was mainly used for experimental research. This is due to the special properties of rhenium, on the one hand, rhenium has extremely high temperature resistance, with a melting point of 3186, second only to tungsten; On the other hand, rhenium has a boiling point of up to 5596, ranking first in the entire periodic table and being the substance with the highest boiling point.
Rhenium is a rare metal with amazing corrosion resistance. No matter whether it is strong acid or alkali, or even known as "aqua regia" that can dissolve ** and platinum, it cannot be eroded.
However, due to the limitation of scientific and technological level and the rarity of rhenium, people have insufficient understanding of its application value, and it was initially mainly used in laboratory research and petroleum catalysis.
It was not until the 50s of the 20th century that rhenium played an important role in modern industry.
The development of jet engines has given rise to the widespread use of rhenium. Initially, when scientists were developing turbojet engines, they noticed a large gap between the turbine blades and the casing, and a relatively low pre-turbine temperature.
Therefore, the deformation of the turbine blades due to high temperature during operation is small, and it is basically within the controllable range.
Scientists have found that the performance of the engine increases significantly after the temperature before the turbine increases. For example, the J52 engine used in the American B-57 bomber has a thrust-to-weight ratio of about 3-4 when the temperature before the turbine is below 1300K.
However, when the J79 engine raises the pre-turbo temperature to 1500K, the thrust-to-weight ratio rises to between 5-6. In order to make better use of the energy of the turbine and fan rotation and improve the utilization of fuel, the turbofan engine came into being.
The emergence of this new type of engine further improves the performance of the engine. For example, the turbofan engine represented by the F100 can reach a pre-turbine temperature of 1700K, and the thrust-to-weight ratio is increased to 7Between 5-8.
As the temperature before the turbine continues to rise, the creep phenomenon of high-temperature nickel alloys gradually intensifies. When the material is exposed to high temperatures for long periods of time or close to the melting point, the deformation becomes more pronounced.
In order to find alloys that are more resistant to high temperatures and creep, scientists have begun to look at rhenium, which is particularly resistant to high temperatures and corrosion. The United States was the first country to include rhenium in engine turbine blade alloys.
Back in the development of the F-15 and F-16 fighter jets, they had already added 3% rhenium to the turbine blades, which scientists found significantly improved the resistance to deformation of the turbine blades.
American scientists, who were excited about this discovery, further increased the amount of rhenium added to the engine of the F-22 to 6%, and the effect was remarkable.
Although ruthenium is added to the alloy to improve its stability, rhenium is still an indispensable element. The strategic importance of rhenium gradually became apparent, and countries that made aero engines began to compete to buy it.
Now, 80% of the world's rhenium is used in aero engine manufacturing. The three major aero-engine giants such as General Electric, Rolls-Royce and Pratt Whitney use 68% of the world's rhenium, and the United States uses the largest amount of rhenium, up to 40 tons per year.
However, rhenium is an extremely scarce resource. According to 2019 data, the annual global rhenium production is about 45 tons, and Chile alone accounts for 49% of the production.
In order to obtain more rhenium resources, the United States has already deployed in many countries with rich rhenium resources around the world, such as Chile and Kazakhstan. By signing long-term contracts, they "monopolized" most of the rhenium production in these countries.
The United States not only mines rhenium in large quantities, but also stores it in case it is needed nowhere to be found. The European Union, Japan, and Russia began to take various measures to "snap up", but due to their late entry, they were temporarily unable to compete with the United States.
Rhenium, a metal that has attracted much attention in the field of aero engines, also has a position that cannot be ignored in the field of rockets and satellites. Because the rocket engine nozzle made of rhenium alloy can withstand more than 100,000 thermal fatigue cycles at a high temperature of 2200, which is incomparable to other materials.
In the 80s of the last century, rhenium alloy nozzles have been used by the American company Hughes in the manufacture of satellites, and the engines of the Apollo spacecraft also use this alloy. In addition, studies in the United States have found that composite materials made of rhenium alloy are minus 267Superconductivity can occur at 15, and although this temperature is still very low, it is already a high critical temperature in superconductors.
Therefore, scientists are studying the application of rhenium in the field of superconductivity, expecting it to make greater contributions to human industrial progress.
China is slightly behind other countries in the development of science and technology and the utilization of rhenium. However, Chengdu Aerospace Superalloy Technology Co., Ltd. successfully discovered rhenium resources in the mine of Longpu molybdenum mining area in 2010, and cooperated with Hunan Nonferrous Metals Research Institute to overcome a number of technical problems after more than a year of hard work, and finally realized the purification of rhenium.
This company is one of the earliest companies in China to start processing and utilizing rhenium.
In the early days, China's aero engine technology was relatively backward, and the demand for rhenium in the domestic market was not large. Aerospace hopes to cooperate with overseas companies to introduce rhenium alloy manufacturing technology through the strategy of "resource for technology".
However, Aerospace soon faced a dilemma: international buyers wanted to sign a long-term agreement and buy all of the rhenium produced by Aerospace Corporation, but this conflicted with the requirements for a technology exchange.
The reason is that all enterprises that master this technology are restricted by US law and cannot participate in technical cooperation. Moreover, due to the technological blockade of China by Western countries, even if Western companies invest in China, their core technologies will be kept secret from Chinese employees.
As a result, aerospace companies need to find a way to meet the needs of international buyers while enabling technical exchanges.
Although Rolls-Royce has built a factory in China, it has set up many obstacles for Chinese employees, and Song Yang, the former deputy general manager of Aerospace, has worked for the company for seven years and has no access to core technologies.
Due to the strict blockade policy adopted by the West against China, the aerospace company made up its mind to develop its own monocrystalline turbine blades for aero engines. Aerospace companies have realized that if they cooperate with Western companies, they will only become an "element merchant", but if they can independently develop monocrystalline turbine blades, they will contribute to better domestic engine research and development.
As a private enterprise, in order to enter the capital- and talent-intensive industry of the aviation industry, it is necessary to overcome many difficulties, such as capital, talents, technology, equipment, etc.
Moreover, they have to produce the most critical and complex monocrystalline turbine blades for aero engines, which is undoubtedly a difficult challenge.
With the help of **, the aerospace company has found several top overseas experts from aero engine giants, who have rich experience in aero engine research and development, testing and maintenance.
However, it is very difficult to get such experts to be willing to go to a foreign country and go to a "little-known" Chinese company that has to start everything from scratch. Aerospace has been repeatedly rejected and almost in a desperate situation.
Fortunately, in 2012, the country's "Twelfth Five-Year Plan" made it clear that it was necessary to break through the core key technologies of aero engines and accelerate the industrialization of aero engine manufacturing.
With the support of the state, Aerospace Company introduced top overseas experts through the "Overseas High-level Talent Introduction Program" and established its own R&D team, and it was at that time that Song Yang joined Aerospace Company.
After the introduction of a team of specialists, the main task of the aerospace company was to solve the problem of equipment. The production of monocrystalline turbine blades required the use of monocrystalline furnaces, but there were no suitable products in China at that time.
So, Song Yang led the team to Europe to find a suitable single crystal furnace. Initially, they tried to buy a monocrystalline furnace from a well-known European manufacturer, but the other party only provided standardized products and was unwilling to customize them according to the needs of aerospace companies.
Eventually, the aerospace company had to look for other solutions. After many attempts, they found a British ** merchant who was willing to customize. After seeing the parameters provided by the aerospace company, the leading company found that their plan was consistent with the plan of advanced Western companies, and believed that the aerospace company had a high probability of overcoming this difficulty.
Although the British company doesn't care what exactly the aerospace company wants to produce with a single crystal furnace, they just want to sell more equipment. However, the aerospace company was not fooled, but bought equipment and trained talent.
In 2015, they successfully developed the first monocrystalline blades. After the verification of the international authoritative test report, the high-temperature tensile performance and high-temperature durability of these single crystal blades have reached the European and American standards.
Although some details need to be further improved, this marks the success of China in breaking the technological blockade of foreign countries and producing its own monocrystalline blades. In 2017, Chengdu became a pilot demonstration city of "Made in China 2025", and Aerospace Company also continued to receive financial support from all levels to continuously improve and develop monocrystalline blades.
Although recent reports show that Aerospace has achieved mass production of monocrystalline blades, we have not seen any reports of domestic monocrystalline blades. This seems to confirm a point reported by CCTV a few years ago: it takes longer to open the market than the production cycle.
Aerospace company's monocrystalline blades may not be able to compare with imported products at present, but we believe that after a long period of research and development, we will see the figure of domestic monocrystalline blades in aero engines in the near future.
In addition, China's monocrystalline blade technology is limited to a certain extent, and there are also shortcomings in rhenium resources. According to the data, the number of new aircraft deliveries worldwide could reach 340,000, which requires 70,000 aero engines, which requires about 1,700 tons of rhenium.
In the face of the global need for about 86 tons of rhenium per year in the future, as well as the demand for military industry and rockets, the earth's rhenium resources will undoubtedly face a severe test. Therefore, we must not only go all out to import and reserve rhenium resources, but also continue to explore the possibility of reducing the dependence of superalloys on rhenium, so as not to be "stifled" by other countries when rhenium resources are more scarce.