Bold innovation 3D printing solves the core problem
In order to solve the above problems, In 2018, Professor Chen Zhangwei and Lao Changshi of Additive Manufacturing Institute of Shenzhen University and Southwest Institute of Physics of China National Nuclear Corporation proposed a new way to develop a tritium producing unit with a new structure by using 3D printing lithium orthosilicate ceramic unit.However, the first problem that 3D printing faces is that lithium orthosilicate is particularly sensitive to the environment, which is easy to react with water and carbon dioxide, causing phase damage and becoming lithium metasilicate.
“To this end, we have carried out strict constraints and control on environmental variables from the storage of lithium orthosilicate powder, the preparation of printable powder paste, the realization of printing technology to heat treatment.For example, the preparation of the slurry is carried out in a glove box filled with inert gas, and the additives are all water-free organic solvents that do not react with lithium orthosilicate.The slurry preparation and 3D printing in such an environment can ensure the phase stability of lithium orthosilicate.Professor Chen Zhangwei told Science and Technology Daily.
In order to quickly solidify lithium orthosilicate powder slurry after 3D printing, we must choose the appropriate solidification forming method.”Ceramic 3D printing has two main ways of curing, one is light curing, and the other is powder sintering or melting.”According to Chen, powder sintering USES a high-energy laser to directly sintering ceramic powder at a high temperature to produce the desired shape, but because of the high temperature, cracking is easy to occur, and the accuracy is poor.Light curing not only has fewer cracking defects and higher printing accuracy, but also has a strong ability to control the details of porous structure.Therefore, the research team chose the way of photocuring and developed a kind of high phase purity lithium orthosilicate powder slurry for 3D printing.
“We mixed selected organic chemical additive components and small dose of photosensitive additive in the lithium silicate powder slurry, which is sensitive to specific wavelength of light. The 405 nanometer ultraviolet light is used to illuminate the slurry to achieve photopolymerization curing of the slurry,” Chen said.
3 d printed structures, and then high temperature sintering, calcined at 1050 degrees Celsius environment realize the vitrified 8 to 10 hours, can get rid of all kinds of additives of solidified structure, and does not react with water and carbon dioxide in the environment, “these chemical additives are added in the physical way, will not damage for lithium silicate.”Chen explained.
The tritium production unit printed by this method is an integrated and defect-free structure. After testing, the reliability problems caused by limited filling rate and stress concentration of the ball bed are overcome, and its stability and mechanical properties are improved by 2 times compared with the traditional microsphere structure.
The tritium production efficiency of the 3D-printed tritium production unit is also expected to be greatly improved.The duty cycle of traditional microsphere structure is up to 65%, while 3D printing can be flexibly adjusted between 60% and 90% according to needs, and the specific surface area of lithium orthosilicate is also significantly increased compared with microsphere structure.
International peers highly praise the 3D printing technology proposed in the manufacturing and application of nuclear fusion core ceramic components is highly innovative.This study has a great prospect in the application of convertor reactor, which will provide more possibilities for replacing the traditional ceramic tritium production structure and promoting the commercialization of tokamak nuclear fusion reaction technology.
What else can 3D printing do for convertibles
We’re still a long way from controlled fusion, but that doesn’t stop us from working toward it.As a new advanced manufacturing method, 3D printing has subverted the traditional manufacturing mode.3D printing technology can realize the integrated forming of complex structures, and is an important innovative method for the manufacturing of complex components with short manufacturing cycle and high material utilization rate.In fusion reactors, too, unique advantages are emerging.
According to professor zhang wei Chen, after increasing material manufacturing institute of shenzhen university and southwest of nuclear physics research institute of nuclear group cooperation, around fusion first wall CLF – 1 SLM process of steel members and organization performance control system work, first to heterogeneous double/multimode organization design idea is introduced into the SLM forming Gao Qiangren RAFM steel development, optimization, based on the strategy of SLM process parameters and scanning SLM forming CLF – 1 steel with both high strength and high plasticity, its comprehensive strength toughness significantly better than the current RAFM steel reported in literatures.
This study provides important theoretical basis and technical guidance for the structural design of 3D printed high strength and tough RAFM steel, and promotes the integrated forming of key components with controllable microstructure and performance.
According to media reports, in 2018, the Hefei Institute of Physical Science, Chinese Academy of Sciences has used 3D printing technology to realize the trial production of the first cladding wall sample, a key component of the reactor.The researchers took CLAM steel as the raw material, and the printed parts met the design requirements. The density of the materials reached 99.7%, which was equivalent to the strength of CLAM prepared by traditional methods.At the same time, the study also found that the lamination and directional solidification characteristics of 3D printing had led to the differences in CLAM microstructure and performance in different directions, which could be effectively reduced or even eliminated in the future by means of scanning scheme optimization and nucleation optimization of molten pool.The research shows that 3D printing technology has a good application prospect in the manufacturing of complex components of advanced nuclear energy systems such as convertor reactors.
With the rapid development of basic science and the continuous change and innovation of 3D printing technology, the exploration of human engineering is full of imagination. It is not impossible that all the components of the future reactor will be made by 3D printing.