The reporter learned from the domestic 3D printing leader Beijing SANDI Technology Co., Ltd: Recently SANDI Technology independently developed a new type of macrostructure suitable for on-site printing, the macrostructure has a strong absorption, flexible control of the performance of the wave absorption, which can meet the demand for wave absorption protection for both existing and new buildings. At present, the company has applied for a number of patents in the field of concrete 3D printing and cement-based wave-absorbing materials, and seven patents have been authorized.

The rapid development of modern technology and electronic industry for human production and life has brought convenience, but also make the human living environment by excessive electromagnetic wave radiation pollution. It is reported that the wave-absorbing material is the use of materials to electromagnetic wave absorption and reduce the electromagnetic wave energy density of a functional material, can reduce the radar scattering cross-section of the facility or equipment, can be widely used in military and civilian fields, in which the macro-structure of the material has a great influence on the effect of the material wave-absorbing. In order to improve the wave-absorbing properties of the material, the industry has tried a variety of methods, but either will reduce the mechanical properties of the material, or increase the cost of the material and the difficulty of production, or mold cost and wave-absorbing properties of the customized cost is high. Both mold-free production and material savings, the use of 3D printing to prepare cement-based wave-absorbing materials has become a development direction of the industry's attention. However, the 3D printing methods that have been reported can only be prefabricated due to the limitation of structural design, and cannot be directly printed and molded on site.

"The 3D printing-based cement-based wave-absorbing materials independently developed by SANDI Technology, with the help of the research and development of a structure called nested, using the characteristics of 3D printing moldless manufacturing, to solve the problem of previous cement-based macro-structural stealth materials needing molds to be prepared, with low strength and uneven wave-absorbing capacity." The relevant person in charge of SANDI Technology said that the optimized design of the wave-absorbing material, with a thickness of 40mm, has a reflectivity of less than -15dB (decibels) and an average reflectivity of less than -20dB in the frequency band of 1~18GHz, which is equivalent to an average absorption rate of electromagnetic energy of 99%, with a large frequency bandwidth and a balanced absorption capacity. "This macroscopic structure of the wave-absorbing material can be realized by the program control to change the print path so as to adjust the structural wall thickness, spacing, height of the structural layer and other parameters, can be adjusted according to the target band of wave-absorbing performance, without the need to prepare molds, to achieve wave-absorbing performance can be customized.

"Relevant data show that in 2019, the global market size of wave-absorbing materials is about 29.75 billion yuan, it is expected that in 2020-2025, the global market size of wave-absorbing materials will continue to expand at a growth rate of more than 8.0%, and the industry has a broad prospect for development. The person in charge said that cement-based wave-absorbing materials can be widely used in the field of environmental protection-type construction to prevent electromagnetic pollution, in order to mitigate the harm caused by electromagnetic radiation to human beings; used in the construction of buildings, bridges, towers, etc., to prevent radar artifacts; used to improve the quality of communications during the construction of communication bases, such as premises and parabolic antennas; used in the airports, wharves, navigational beacons, television stations and receiving stations near the tall buildings It can be used to eliminate reflection interference; used to make microwave darkroom, can prevent microwave radiation interference and energy leakage, not only can eliminate interference to improve the test accuracy, and also can play a protective role for the operator; in addition, it can be used in the field of military stealth building in combat, scientific research departments of anti-electromagnetic wave interference, precision instrument factories and national confidentiality units to prevent the leakage of information and other departments.

(Source: Economic Times)