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News investigation: The ten thousand-meter deep diving road of the “Struggle”

News investigation: The ten thousand-meter deep diving road of the "Struggle"

This is the fourth in human history.

The “Struggle” of the deep manned submersible

On this day, it will enter the deepest sea in the world.

Challenge to the ten thousand-meter ocean floor

On November 10, 2020, China’s “Struggler” manned submersible set a new record of 10,909 meters of China’s manned deep diving in the Mariana Trench, marking that China has reached the world’s leading level in the field of large-depth manned deep diving.

Behind the success of the development and sea trials of the Struggler

What are the stories? The first step of a 10,000-meter deep dive: overcome underwater pressure

In mid-December, in the engineering laboratory of the Institute of Deep Sea of the Chinese Academy of Sciences, the Struggler, which set a new record for manned deep diving in China, was being tested here.

When human beings want to enter the deep sea, the pressure of water is the enemy that will always accompany you. Under the sea floor of 10,000 meters, it is necessary to bear about 11,000 tons of pressure per square meter, which is equivalent to putting one ton of cars on your fingers.

The manned module is the core and key component to provide a safety barrier for submariners underwater, which also marks the technical level of a country’s manned submersible.

How can new materials drive industrial progress with high strength and toughness?

Judging from the international manned deep diving pattern, since the 1990s, the United States, France, Japan, Russia and other countries have mastered large-depth manned diving technology.

For nearly 30 years, the manned cabins of most deep submersibles in these countries have been made of an alloy called “Titanium 64”, which is the most used, most complete and experienced titanium alloy.

However, when it comes to the “Struggler”, the manned cabin has to withstand extreme pressure at a depth of 10,000 meters, and on the other hand, it also needs to meet the larger ball cabin design with three people. Under such conditions, the titanium 64 alloy cannot meet the standard.

To solve the problem of manned cabin materials, the development of a new titanium alloy with higher strength has become the only way out. In 2014, two years before the establishment of the “Struggler”, the Chinese Academy of Sciences implemented a strategic pioneering science and technology project.

The Metal Research Institute in Shenyang is responsible for conducting research, demonstration and pre-research on manned cabin materials and manufacturing.

In order to develop the new material of the manned cabin of the Struggler, titanium alloys with different distribution ratios have been processed and tested in this workshop of the Institute of Metals of the Chinese Academy of Sciences.

Ma Yingjie, researcher of the Institute of Metals of the Chinese Academy of Sciences: Mix sponge titanium, aluminum, fertile, etc., and press it into an electrode of titanium alloy through a large pressure device. Then put it in the smelting furnace, and after many vacuum smeltings, it can be refined into titanium alloy ingots.

The titanium alloy material of the “Struggler” manned cabin should have high strength and high toughness at the same time, which is a worldwide problem in the field of materials science and the scientific direction of researcher Ma Yingjie’s long-term research.

The picture displayed by Ma Yingjie is a microstructure within 5 microns of the new titanium alloy material.

The realization of composite sheet microstructure and other breakthroughs in basic scientific research have comprehensively improved the performance of the new titanium alloy.

Yang Rui, researcher of Institute of Metals, Chinese Academy of Sciences: Traditional titanium alloys, with strength and toughness, have developed a series of alloys. ( We) make a submersible, which drives the progress of industry and materials, which can be used elsewhere.

The cumulative benefits are immeasurable.

After the strength and toughness met the standards, the metal institute solved the problem of weldability of materials.

From 2014 to 2016, through more than two years of technical breakthroughs, the scientific research team developed a brand-new titanium alloy, titanium 62A, and the material problem of the manned cabin spherical shell was solved easily.

Three solutions to overcome world problems

The new material provides a material basis, but there is still a long way to go before the successful construction of the manned module.

Key technologies such as super-thick sheet preparation, hemispheric integral stamping, electron beam welding and so on need multiple units in various fields to jointly solve key problems, which also tests the country’s industrial manufacturing capacity.

Li Yanqing, deputy chief designer of the 702 “Struggler” of China Shipping Group: Two hemispheres, weld together to form a whole ball.

The core is these welds, including the orifice welds, and the most core equatorial welds.

Ensuring that the toughness of the weld position meets the requirements is a worldwide problem facing welding technology, and it is even more difficult to achieve one-time welding of all-electronic beams of super-large size and thickness materials.

Lei Jiafeng, researcher of the Institute of Metals of the Chinese Academy of Sciences, deputy chief designer of the manned submersible “Struggler”: At the beginning of the development, we listed many key technologies.

Welding was our biggest concern, because it was the most difficult.

The manned submersible “Dilong” was processed and manufactured abroad in 2012; the 4,500-meter manned submersible “Deep Sea Warrior”, which was launched in 2018, was domesticated.

At that time, three technical solutions were adopted.

Deputy Chief Designer of China Shipping Group 702 “Deep Sea Warrior” Chief Designer of China Shipping Group 702 “Deep Sea Warrior” Hu Zhen: (We used) three craft routes and made three balls (manned cabins).

Of course, these three balls (manned cabins) are currently in a usable state, with one ball ( manned cabin) is in service on the Deep Sea Warrior. Overcome three difficulties to build the world’s largest manned cabin

Similar to Deep Sea Warrior, in order to build the manned cabin of the Struggle, the Institute of Metals of the Chinese Academy of Sciences has designed two different welding schemes, and plans to build two ball chambers, but both schemes have certain risks.

In December 2018, the first welding scheme went wrong. The manned capsule shell could not be used, so we could only place our hope on the second scheme.

At this time, the time schedule was already very tight, and the team members were under great pressure.

On June 17, 2019, the manned cabin using the second welding scheme began to weld at 725 of China Shipping Group in Luoyang. The engineering unit completed the equatorial seam welding at one time, and the quality and toughness of the weld can fully meet the design requirements. 

In the end, the manned cabin team built the world’s largest and largest submersible manned cabin for the Struggler using a new titanium alloy material invented by itself.

Yang Rui, researcher of the Institute of Metals of the Chinese Academy of Sciences: Three difficulties, one material, one processing and molding, and one welding, are borne by three large state-owned institutions.

Realize the concentration of doing major things. Rapid innovation, rapid industrialization, and rapid national importance.

How to ensure the safety of the submersible when diving and floating?

Zhang Jingjie, a researcher at the Institute of Physical and Chemical Technology of the Chinese Academy of Sciences, is responsible for the buoyancy materials developed by her scientific research team, which provide guarantee for the smooth diving and safe floating of the submersible.

Zhang Jingjie, researcher of the Institute of Physical and Chemical Technology, Chinese Academy of Sciences: After diving to the seabed, we have to go up after the operation. There are two forms. One is to consume energy and push it up with power, but the operating time and operation of the submersible underwater will be shortened, and the radius of activity will be smaller.

Therefore, to use a non-powered floating technology, you can also bring the submersible without consuming power, and solid buoyancy materials are used.

When a manned submersible is launched, it should carry two sets of ballast iron and dive deep into the ocean under gravity traction. Near the seabed, the submersible will throw off the first group of ballast iron to achieve equilibrium suspended in the water and operate on the seabed.

After completing the operation, the submersible throws off the second group of ballast iron, so that the buoyancy force is greater than its own gravity, and floats up and returns. The performance of buoyancy materials is directly related to the safety of submersibles and submariners.

According to Zhang Jingjie, without solid buoyancy materials, the submersible cannot go down, because it can never go up again after going down, so this is a very critical link.

In the picture taken in high-speed camera mode, the scattered white powder is the original state of the buoyancy material. It may be hard for you to imagine that each of these powders is a hollow sphere.

The scientific name of this material is hollow glass microspheres. Using it to make solid buoyancy materials not only needs to be light enough, but also needs to be resistant to high pressure.

For a long time, domestic buoyancy materials have generally had high density and poor strength, which greatly hindered the process of deep-sea scientific research in China.

Worldwide, only a few countries have the core technology and impose a technical blockade on our country. China’s first manned submersible “Dilong”, which was launched in 2012, imported from the United States. Hu Zhen, deputy chief designer of the “Dilong”, told us such a story.

After all kinds of difficulties: technology must be in your own hands

According to Hu Zhen, deputy chief designer of the “Jililong”, he had communicated with the manufacturer at that time. The proportion of purchasing buoyancy materials was 0.52, while (actually) it was sold to them 0.56, which was lowered by a higher level.

The weight of the submersible will soon rise, and the same buoyancy needs to use more raw materials. A set of things originally designed has to be restarted, which has a great impact on the submersible.

The technology must be in your own hands, so that the road can get wider and wider.

In 2014, the Institute of Physics and Chemistry of the Chinese Academy of Sciences took the lead in solving the independent research and development of buoyancy materials. They have years of technology accumulation in this field.

In the 1990s, in the formulation experiment of solid glass balls, they failed, and they accidentally found hollow microspheres floating on the water.

Because of their lightweight insulation and other characteristics, the Institute of Physics and Chemical Technology has carried out long-term research and attention to its performance and application.

There is no technical path to refer to the preparation of solid buoyancy materials, and the development process is extremely arduous. After thousands of failures, the Institute of Physics and Chemistry of the Chinese Academy of Sciences finally prepared solid buoyancy materials with high safety coefficients and mass production.

In 2018, the standard block of solid buoyancy materials completed the pressure test at the Institute of Deep Sea of the Chinese Academy of Sciences.

10,909 meters The Struggler explores the deepest point of the seabed

In December 2020, the mother ship “Exploration One” of the Struggler was quietly moored in Sanya’s harbor. In the previous 10,000-meter sea test, it played an important supporting role on the water surface.

Bao Gengsheng, the deputy chief designer of the Struggler, in addition to improving the support system of the mother ship Discovery One, he is also responsible for an important task to determine the specific diving point of the Struggler to go to the Mariana Trench for sea trials.

How to choose the location of 10,000 meters deep diving? In the sea test, is the depth record of 10,909 meters the deepest point of the ocean?

Bao Gengsheng, deputy director of the Marine Equipment and Operation Management Center of the Deep Sea Institute of the Chinese Academy of Sciences: The mange is a narrow and long trench, so it is actually the deepest place, the eastern part, the western part, 2017 “Ocean 6” and 2018 “Exploration One”, we measured the west (by acoustic method) at that time (using acoustic methods) This piece is plus or minus 15 meters in 10,925, and the eastern part is measured to be 10927 plus or minus 15 meters.

According to Bao Gengsheng, the depth of 10,909 meters is the depth measured by the pressure sensor of the Struggler, which is usually smaller than the water depth measured by acoustic methods.

Hydroacoustic communication is the only bridge between the Struggler and the mother ship Discovery One, which can realize the real-time transmission of data, text, voice and images from the submersible from the seabed to the mother ship at sea.

On November 10, during the live broadcast of the sea test, the call between the submariner and the mother ship at the seabed was completed through the underwater acoustic communication system.

Zhu Min, Researcher of Institute of Acoustics, Chinese Academy of Sciences: The communication we usually use is a communication system based on electromagnetic waves. We refer to communication system for short.

In fact, the full name should be radio communication or electromagnetic wave communication, mobile phone signal, radio wave signal, or optical signal. If it travels in the seawater, in fact The distance is very short.

On the Struggler manned submersible, these cylindrical metal shell equipments are the key materials of underwater acoustic communication systems – acoustic transducers.

Compared with the previous two generations of Manned Submersibles, the underwater acoustic communication equipment of Struggler has been fully localized.

In addition to communication, a variety of other acoustic equipment also provide positioning, detection, obstacle avoidance and other functions for submersibles.

Magic Robot: Explore the mysterious underwater world

In the “Struggler” sea test, the manipulator of the submersible is the core operating tool. Through the manipulator, the sampling of seabed organisms, seabed sediments and rocks, and the deployment and recovery of scientific research equipment are realized.

The “manipulator” of the Struggler has seven joints, which can achieve 6 degrees of freedom movement control and has a weight holding capacity of more than 60 kilograms.

The manipulator was independently developed by Shenyang Institute of Automation of the Chinese Academy of Sciences, breaking through 10,000-meter sealing technology, ultra-high pressure oil environment drive and control and other technologies, filling the gap in China’s hydraulic manipulator to carry out 10,000-meter operations.

Ten thousand meters deep diving: one step closer to no man’s land

The ocean occupies 71% of the earth’s surface, but human understanding of space and the moon exceeds that of the deep sea area, and the 10,000-meter abyss is the “no man’s land” for human scientific research.

The deep sea area below 6,000 meters is the frontier field to solve major scientific problems such as the origin of life and the evolution of the earth.

Different from the positioning of some manned submersibles as exploration equipment, the “Struggler” manned submersible will be put into use as normal scientific research equipment in the future, which will help China make original and foundational contributions to the scientific research of the deep underwater abyss in the future.

Jiang Lei, researcher of the Institute of Deep Sea of the Chinese Academy of Sciences: The “Struggler” has only completed the sea test and is about to be put into operational.

Frequent diving requires strong operational ability and hardware and software guarantee. We hope that the “Struggler” can invest in normal scientific research more efficiently and at a relatively low cost, providing a good platform for scientists in our country and scientists from other countries in the world, and can have better Scientific discovery.

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