There are currently three “Sky Observing Eyes” in the world. The first is the 500-meter spherical radio telescope (FAST) located in Guizhou Province, China; the second is the Arecibo 350-meter telescope in the United States, built in 1992, China`s “FAST” The overall performance of "FAST" is 10 times stronger than that of Areciboyo. The third is the 100-meter telescope in Bonn, Germany. The sensitivity of China's "FAST" is about 10 times higher than that.
China`s “FAST” spherical radio plate is made of aluminum alloy. The materials used for spherical radio telescopes in Germany and the United States have not been reported. The ALMA telescope of the Nobeyama Space Radio Institute of Japan’s National Astronomical Observatory uses 5052 aluminum alloy. The plate and support structure are made of 6061 aluminum alloy extruded material, which can work for a long time in the environment of -20℃～20℃. The construction site has an elevation of 5000 meters. It was completed at the end of September 2011 and put into use in early 2012. There are 10 units in total. The spherical diameter is 45 meters.
Japan's Nobeyama uses 5052 and 6061 aluminum alloys to build a 45-meter telescope
The Nobeyama Space Radio Observatory of Japan`s National Astronomical Observatory has 10 spherical telescopes (antennas) with a diameter of 45 meters and a height of 50 meters. It was completed in 1971. The spherical telescope is located on a 50-meter-high frame. The spherical surface is made of 5052 aluminum alloy sheet. The bracket is made of 6061 aluminum alloy extruded profile and processed by EDM.
It is very challenging to process the surface of the antenna, because the smoother the surface is to receive the shorter radio waves, it must be processed with a certain strength and high toughness aluminum alloy. Its surface roughness should be ≤25 nanometers and at the same time within -20 This accuracy is still maintained in an environment of ℃～+20℃. The spherical antenna with a diameter of 12 meters is laid with 205 pieces of 1 meter × 1 meter aluminum plates, and the thickness of the raw material is 30 mm. It is cut and processed layer by layer in nanometer units. Each piece has an extremely precise parabola. To form a large paraboloid, 37 different shapes of aluminum blanks are used.
In order to manufacture an antenna with a diameter of 45 meters and a maximum height of 50 meters, the biggest problem encountered is how to reduce its own mass, because its parabolic area is 1,590 square meters and its mass is 700 tons. In order to reduce the weight, the surface layer (mirror body) of the antenna adopts sandwich carbon fiber reinforced plastic honeycomb aluminum plate. In order to avoid deformation of the frame due to direct sunlight, a heat-insulating aluminum plate is installed on the back of the antenna. After this meticulous design, this millimeter wave telescope stands out among the world's equipment of this kind, ranking the top in the world, with the mirror accuracy maintained at about 170 microns, and aluminum alloy has played an irreplaceable role in these super antennas.
5052 aluminum alloy is the best material for making spherical radio telescopes
The parabolic surface of the spherical radio telescope with a diameter of less than 3 meters can be made of a whole piece of aluminum alloy, because the cold rolling mill with the largest roll surface width in the world today is 4350 mm, and the spherical radio telescope with a larger diameter needs to use a block of parabolic aluminum alloy. Plate splicing, the 45-meter telescope of the National Astronomical Observatory's Nobeyama Universe Institute, the U.S. Puerto Rico Observatory Telescope, the German Bonn Observatory Telescope, and the Brazilian Observatory Telescope's paraboloids are all made of special-shaped 5052 aluminum alloy plates because of cold rolled 5052 aluminum Alloy plate is the best material for manufacturing this parabolic panel.
Why are all paraboloids made of 5052 aluminum alloy? Because it has a series of excellent performance. It was introduced to the market by Alcoa in the late 1920s. Its calibrated composition (mass%): Si0.25, Fe0.40, Cu0.10, Mn0.10, Mg2.2～2.8, Cr0.15～0.35, Zn 0.10, other impurities are individually 0.05, totaling 0.15, and the rest is aluminum. It can be seen from the Al-Mg series phase diagram that the solubility of Mg in aluminum is second only to that of Zn, and its limit solubility at 450°C is 17.4% and only 1% at room temperature. In theory, Al-Mg alloys should have Considerable age hardening effect, but due to the limitation of the intergranular precipitation tendency and dispersion of β phase (Mg2Al3), it is generally not valuable and necessary to use this effect. It can be used in annealing and cold work hardening conditions.
Aluminum alloy materials in China FAST
The high-precision aluminum alloy plates and extruded aluminum materials used in China's "FAST" are all provided by ZLXN Aluminum Technology Group, which consists of 4450 aluminum alloy reflective surface units. In addition to the official opening of the first "FAST", China also has a "grassland MUSER" in the depths of the Inner Mongolia grassland that specializes in "seeing" the sun. It covers an area of 10 square kilometers and is lined with 100 white parabolic antenna arrays. This is the reputation The Mingantu radio spectrum heliograph group, which is the "Prairie Eye", is abbreviated as MUSER. The construction of the MUSER project started in 2008, and a series of solar radio observations began in 2013. It will also invest 130 million yuan in the second phase of construction, covering an area of 215 acres. It is expected to be completed in 2023 and put into use in 2025.
In early July 2015, ZLXN and FAST reflective panel production plant formally signed all orders for 800 tons of aluminum alloy reflective panels and aluminum plate structural parts.
The FAST project is one of China’s recent nine major scientific and technological infrastructures. Being able to participate in the construction of this major national project means for ZLXN not only the high recognition of material quality and the manifestation of benefits, but also ZLXN’s performance Science and technology special engineering materials guarantee.
The reflective surface area of this world's first "FAST" is equivalent to the area of nearly 30 football fields. It is composed of 4450 reflective surface units. After receiving the aluminum alloy strip from ZLXN, the manufacturer will cut it into The blanks were then machined and processed into the required shape and size. It took 11 months from the installation of the first reflective surface on August 2, 2015 to the completion of the installation on July 3, 2016.