As the main rocket for the construction of China’s manned spaceflight engineering space station, the Long March 5B launch vehicle represents the highest level of Chinese launch vehicle technology. On the basis of inheriting the excellent “genes” of the Long March 5 rocket, there are also Many pioneered "high-tech" aerospace. The moment the rocket fired and fired, the temperature was as high as more than 2,000 degrees Celsius, enough to melt most metal and non-metal materials. In addition, because the gap between the heat-resistant shield and the rudder is small, the dimensional accuracy of the heat-resistant shield is very high, and it must also have a high temperature rating, high temperature bearing capacity, and low temperature deformation.
The traditional heat-resistant shield adopts the scheme of titanium alloy external spraying heat-resistant coating, but its coating is easy to come off, the reliability is poor, and the quality is too heavy. With the further improvement of aircraft performance requirements, its weight loss requirements are becoming more urgent, and traditional metal solutions have seriously hindered its weight loss requirements. In addition, if the phenolic resin-based composite material is used to prepare the heat-resistant shield, its temperature resistance level is insufficient, and high temperature air flow will cause damage or large thermal deformation; using 2D laminate composite material, bubbling will occur at high temperature Layering phenomenon; the above will cause interference between the heat-resistant shield and the rudder, which will seriously affect the movement of the rudder and cause the aircraft to fail to fly.
2 cm thick, can withstand 2500 degrees high temperature
Based on the above deficiencies, ZGHT Aerospace Materials and Technology Research Institute has independently developed a new launch platform protective board using high temperature resistant phthalonitrile material and nearly one hundred layers of reinforced cloth, which can not only withstand the high temperature of the rocket tail flame at 2500 degrees Celsius, but also Reusable. Yang Kunxiao, the developer of the material, introduced that the surface of the traditional rocket launching platform is protected by scraping the inorganic coating. However, when the rocket is launched, the large heat tail flame of the jet will cause the inorganic coating to scatter, generating a large amount of smoke and excess, and causing partial damage to the launch platform. After each rocket launch, the ground staff must repair the local damage location of the launch platform, and the inspection, confirmation and local repair of the inorganic coating are very time-consuming. Is there a method that can be used for convenient maintenance and stronger protection? To this end, the developers have carried out research on the forming technology of reusable composite protective plates. "The newly developed composite shield is mainly made of high-temperature-resistant phthalonitrile material and nearly 100 layers of reinforced cloth. Although it is only 2 cm thick, it can isolate the high temperature of nearly 2500 degrees Celsius and withstand the rocket launch. The external impact of high temperature and high load." Yang Kunxiao introduced that the newly developed protective plate is mainly placed in the core area of the launch platform, because the core area is closest to the rocket flame center, and there are many pipes, monitors and other equipment below the core area. The protection is directly related to whether the rocket can be successfully launched.
Protective board made of high temperature resistant phthalonitrile material and nearly one hundred layers of reinforced cloth
In order to avoid the defect that the reinforcing cloth will cause delamination and bulging under the impact of large heat flow and high temperature, the developers also adopted a new stitching technology. Yang Kunxiao said: "This stitching technology is like'shoe sole', through a thread to reinforce the cloth back and forth, stitching nearly 100 layers of reinforced cloth together." At the same time, the protective plate maintenance method is also very simple and convenient, the rocket launch After that, you only need to simply clean and spray another layer of paint, and the launch platform will be completely new and you can proceed to the next mission. According to reports, at present, the protective board can be reused 5 times in a row. It has been used in the launch of the Long March V rocket, which has greatly improved the maintenance efficiency of the rocket launch platform and is also of great significance for future high-density rocket launches.
The products made of phthalonitrile composite material heat-resistant shield molding technology have high temperature resistance grade, good dimensional stability, low temperature deformation, good bearing capacity, and significant weight reduction effect, which solves the problem of too heavy quality of traditional metal solutions. It solves the problems of insufficient temperature resistance grade of the phenolic resin-based composite material scheme and large dimensional deformation at high temperature, and is suitable for the preparation of high-dimensional precision high-temperature composite materials.