At 21:25 on September 29, 2011, China’s self-developed manned aircraft, “Tiangong No.1”, successfully entered the planned orbit and the launch was a complete success. The target number of the "Tiangong No. 1" target aircraft is 10.4m, weighs about 8.5t, and the cabin structure has a large diameter of 3.35m. It has a running height of about 370km and a running time of 2 years on the track, which can be docked several times with the manned spacecraft. “Tiangong No.1” is a two-cabin structure, one is the test cabin and the other is the resource compartment. The former is sealed and is the place where the astronauts live and work. They are divided into sealed sections and unsealed sections. The seal section is the astronaut's activity zone, and all scientific test equipment is installed in the unsealed section.
"Tiangong No.1", a low-orbit, long-life large manned spacecraft in China, has a design life of two years. In the rear cabin of the resource compartment, which is the “Tiangong No.1”, a power system (large solar panels with super power) is used to propel the system and energy. Its main task is to provide energy protection for the flight of "Tiangong No. 1" and control the flight attitude. The weight of the resource compartment after adding fuel is about 1.4t.
All the equipment (solar battery wings) of the "Tiangong-1" power sub-system are in the resource compartment, and the fuel stored in the cabin provides operating energy for the aircraft. There is also a very critical part in the cabin - the control moment gyro, used to control the flight attitude of "Tiangong No. 1", weighing about 50kg, is made of non-ferrous materials.
The resource compartment loses more than 10%, and the aluminum-lithium alloy is indestructible.
"Tiangong No. 1" will be in orbit for two years. The resource compartment will not only have solar cells, power systems and propulsion systems, but also control the torque gyro, and must also add enough fuel. Therefore, it is necessary to reduce the weight of the structural part of the cabin. Due to the high density of conventional high-strength 2XXX alloys and ultra-high-strength 7XXX alloys, designers want to use aerospace aluminum alloys that are comparable in performance to conventional structural aluminum alloys, and whose density is smaller than their smaller ones. Lithium alloy, an important feature of it is its low density and high modulus of elasticity. In aluminum alloys, lithium and niobium are effective alloying elements to reduce their density. Lithium has a large solubility in aluminum of 4.2%. For every 1% lithium added to aluminum, its density can be reduced by about 3%, and its elastic modulus. The volume increased by about 5%.
The countries and enterprises that can produce aluminum-lithium alloys in the world are: China Southwest Aluminum (Group) Co., Ltd., Alcoa's Davenport Works, Rio Tinto, USA. Ravenswood Aluminium of Rito Alcan and Issoire of France, British Alcan of the United Kingdom, Kamensk of United Aluminum Corporation of Russia (Kamensk) aluminum processing plant. China developed aluminum-copper-lithium alloy S141 in the early 1960s. In the mid-1990s, Southwest Aluminum (Group) Co., Ltd. introduced aluminum-lithium alloy vacuum melting furnace and casting equipment from Russia. From then on, China can mass produce aluminum. - Lithium alloy sheets, profiles and forgings.
Lithium is a chemically active metal element. Therefore, the aluminum-lithium alloy must be smelted in a vacuum furnace. The melt must also be cast under a protective gas. The casting is a key technology for producing aluminum-lithium alloys.
China's large aircraft C919 passenger aircraft fuselage and other straight section is also made of aluminum-lithium alloy, manufactured by AVIC Hongdu Company, has been successfully off the assembly line in early December 2010, all aluminum-lithium alloy sheets from the United States Provided by the aluminum company, from the Davenport plant. The straight section is located at the front of the fuselage fuselage, and is a simple structural section of equal width, with a total length of 7.45m, a width of 4.2m, and a height of 4.2m. It is the first section of China's domestic civil aircraft to be made of aluminum-lithium alloy.
NASA also selected Alcoa in 2008 to produce aluminum-lithium alloy sheets for its Ares No. 1 manned launch vehicle, of which only 453.6t was ordered, all using 2195 aluminum-lithium. Alloy (% by mass: 0.12Si, 0.15Fe, 3.7~4.3Cu, 0.25Mn, 0.25-0.8Mg, 0.25In, 0.10Ti, 0.25-0.6Ag, 0.8-1.2Li, 0.08-0.16Zr, other impurities each 0.05 , a total of 0.15, the rest is Al) rail system. The alloy was finalized in 1992 and registered with the American Aluminum Association (AA) and was developed by Alcoa. The ingots are produced by Alcoa's Pittsburgh Technology Center and the Davenport plant is rolled.
Aerospace aluminum star - old and advanced aluminum-lithium alloy family
Aluminum-lithium alloy is an old and advanced high-precision aerospace material. Only 7 plants in 5 countries can produce plates, 11 can produce extruded profiles, and 9 plants can produce forgings and alloys. The key to the material is smelting and casting, so the number of smelting and casting companies determines the number of such high-thickness alloy materials. As for extrusion and casting, there is no special process for aluminum-lithium alloys, and most of them can produce heat-treated reinforced aluminum. Alloy materials can be produced by companies.
It is said that the aluminum-lithium alloy is an old alloy because in the early 1920s Germany developed a lithium-containing aluminum alloy under the trade name "Scleron", typical composition (% by mass): 12Zn, 3Cu, 0.1Li. In 1942, Lebron of Alcoa applied for a patent for X2020 alloy (Al-4.5Cu-1.0Li-0.8Mn-0.5Cd). In 1957, the alloy sheet was applied to the US Navy's A3j reconnaissance aircraft. In the early 1960s, it was also used in the supersonic bomber B-58 and the fighter F-111. However, the application of this alloy has not been promoted due to its low fracture toughness and sensitivity to the notch much larger than that of the 7075 alloy. Later, the former Soviet Union developed the 01420 and BA 23 aluminum-lithium alloys. In 1971, the British Fulmer research system produced a new aluminum-magnesium-lithium-zirconium alloy. Especially after the oil crisis of 1973, the aluminum-lithium alloy boom was again developed to solve the low toughness of the alloy. With breakthrough achievements in grain boundary brittleness, since the 1980s, some companies in various countries have successively launched a number of high-performance aluminum-lithium alloys, which have good comprehensive performance in current and future aviation. Widely used in the device.