Space Materials Science in China:Ⅱ.Ground-based Researches and Academic Activities

Activities of space materials science research in China have been continuously supported by two main national programs.One is the China Space Station(CSS)program since 1992,and the other is the Strategic Priority Program(SPP)on Space Science since 2011.In CSS plan in 2019,eleven space materials science experimental projects were officially approved for execution during the construction of the space station.In the SPP Phase Ⅱ launched in 2018,seven pre-research projects are deployed as the first batch in 2018,and one concept study project in 2019.These pre-research projects will be cultivated as candidates for future selection as space experiment projects on the recovery of scientific experimental satellites in the future.A new apparatus of electrostatic levitation system for ground-based research of space materials science and rapid solidification research has been developed under the support of the National Natural Science Foundation of China.In order to promote domestic academic activities and to enhance the advancement of space materials science in China,the Space Materials Science and Technology Division belong to the Chinese Materials Research Society was established in 2019.We also organized scientists to write five review papers on space materials science as a special topic published in the journal Scientia Sinica to provide valuable scientific and technical references for Chinese researchers.

Space Materials Science in China:I.Experiment Studies under Microgravity

The virtual absence of gravity-dependent phenomena in microgravity allows an in-depth understanding of fundamental events that are normally obscured and therefore are difficult to study quantitatively on Earth.Of particular interest is that the low-gravity environment aboard space provides a unique platform to synthesize alloys of semiconductors with homogeneous composition distributions,on both the macroscopic and microscopic scales,due to the much reduced buoyancy-driven convection.On the other hand,the easy realization of detached solidification in microgravity suppresses the formation of defects such as dislocations and twins,and thereby the crystallographic perfection is greatly increased.Moreover,the microgravity condition offers the possibilities to elucidate the liquid/solid interfacial structures,as well as clarify the microstructure evolution path of the metal alloys(or composites)during the solidification process.Motivated by these facts,growths of compound semiconductors and metal alloys were carried out under microgravity by using the drop tube,or on the scientific platforms of Tiangong-2 and SJ-10.The following illustrates the main results.

Progress on Space Materials Science in China:Debris Shielding Fibrous Materials and High Specific Energy Lithium Sulfur Batteries

The development of China’s space industry puts forward urgent requirements for high-performance debris shielding materials and high energy density rechargeable battery.In this review,the recent progress on debris shielding fibrous materials and high energy density Li-S battery are particularly summarized.According to the experimental results,basalt fibers and silicon carbide fibers were chosen as the effective filling shielding materials.The geometric structure of fabrics was also investigated.For the novel shielding materials,high-strength and flexible silicon carbide micro-nano fibrous membranes were designed and fabricated.The obtained membranes with excellent mechanical properties portend the potential applications in debris protection structure.Furthermore,the high specific energy lithium sulfur batteries have made remarkable progress in fundamental research and application research in recent years.In order to solve the key problems of polysulfides shuttle and slow redox kinetics in lithium sulfur battery,a series of transition metal compound@hollow carbon-based material as sulfur host with dual functions of catalysis and adsorption towards polysulfides were designed and constructed.The obtained Li-S pouch cells with high areal sulfur loading of 6.9 mg·cm^(-2)yield exceptional high practical energy density of 382 W·h·kg^(-1)under lean electrolyte of 3.5μL·mg^(-1),demonstrating the great potential of realistic high-energy Li-S batteries.

From Nowhere Pioneer a New Path and Be of One Mind to Ascend the High——Profile of the Space Materials Research at Northwestern Polytechnical University

At the end of 2001 National Natural Science Foundation of China (NSFC) organized a laboratory evaluation for Creative Research Groups, a pilot program launched in 2000, in the northwestern area of China and the evaluating team was deeply impressed by a young group, around 30 of average age, with their work and achievements, with their effort in pursuit of scientific truth and with their teamwork spirits. They all acknowl-

THE DGW-I FURNACE A MATERIALS PROCESSING FACILITY IN "SZ-2" SPACECRAFT

The DGW-I is a new material processing facility developed in China,which was firstly carried into orbit in November 1999 by the SZ-1 spacecraft and then in January 2001 carried by SZ-2 into space again,and successfully processed 6 samples of materials,including 3 samples of alloys,2 of semiconductors and 1 sample of oxide crystal.

Progress of Materials Science in Space Technology in China(2020-2022)

In this paper,the main research work and related reports of materials science research in China’s space technology field during 2020-2022 are summarized.This paper covers Materials Sciences in Space Environment,Materials Sciences for Space Environment,Materials Behavior in Space Environment and Space experimental hardware for material investigation.With the rapid development of China’s space industry,more scientists will be involved in materials science,space technology and earth science researches.In the future,a series of disciplines such as space science,machinery,artificial intelligence,digital twin and big data will be further integrated with materials science,and space materials will also usher in new development opportunities.

Recent Progress in Space Science and Applications on Chinese Space Station in 2022–2024

Chinese Space Station(CSS)has been fully deployed by the end of 2022,and the facility has entered into the application and development phase.It has conducted scientific research projects in various fields,such as space life science and biotechnology,space materials science,microgravity fundamental physics,fluid physics,combustion science,space new technologies,and applications.In this review,we introduce the progress of CSS development and provide an overview of the research conducted in Chinese Space Station and the recent scientific findings in several typical research fields.Such compelling findings mainly concern the rapid solidification of ultra-high temperature alloy melts,dynamics of fluid transport in space,gravity scaling law of boiling heat transfer,vibration fluidization phenomenon of particulate matter,cold atom interferometer technology under high microgravity and related equivalence principle testing,the full life cycle of rice under microgravity and so forth.Furthermore,the planned scientific research and corresponding prospects of Chinese space station in the next few years are presented.

Recent Progress of Microgravity Science Research in China

Microgravity science is an important branch of space science.Its major objective is to study the laws of materials movement in microgravity,as well as to reveal the influence of gravity on the movement of materials in different gravity environments.Application researches relevant to these basic studies are also important contents of microgravity science.The advanced subjects,to some extent,reflect the ability of human beings to understand nature and the R&D level in this field in various countries.In this paper,the recent progress and the latest achievements of microgravity science and application researches in China aboard space platforms such as the Core Capsule Tianhe of the China Space Station(CSS)and satellites,as well as utilizing ground-based short-term microgravity facilities such as the Drop Tower Beijing and TUFF,are summarized,which cover the following sub-disciplines:microgravity fluid physics,microgravity combustion science,space materials science,space fundamental physics,space bio-technology,and relevant space technology applications.

A structural topological optimization method for multi-displacement constraints and any initial topology configuration

In density-based topological design, one expects that the final result consists of elements either black （solid material） or white （void）, without any grey areas. Moreover, one also expects that the optimal topology can be obtained by starting from any initial topology configuration. An improved structural topological optimization method for multidisplacement constraints is proposed in this paper. In the proposed method, the whole optimization process is divided into two optimization adjustment phases and a phase transferring step. Firstly, an optimization model is built to deal with the varied displacement limits, design space adjustments, and reasonable relations between the element stiffness matrix and mass and its element topology variable. Secondly, a procedure is proposed to solve the optimization problem formulated in the first optimization adjustment phase, by starting with a small design space and advancing to a larger deign space. The design space adjustments are automatic when the design domain needs expansions, in which the convergence of the proposed method will not be affected. The final topology obtained by the proposed procedure in the first optimization phase, can approach to the vicinity of the optimum topology. Then, a heuristic algorithm is given to improve the efficiency and make the designed structural topology black/white in both the phase transferring step and the second optimization adjustment phase. And the optimum topology can finally be obtained by the second phase optimization adjustments. Two examples are presented to show that the topologies obtained by the proposed method are of very good 0/1 design distribution property, and the computational efficiency is enhanced by reducing the element number of the design structural finite model during two optimization adjustment phases. And the examples also show that this method is robust and practicable.

Baoti Group Supplied 90% Titanium Alloy Material to China's Air and Space Industry

On September 5,the journalist learned from the Shaanxi Province State-owned Assets Supervision and Administration Commission that,as the key R&D production base of Titanium alloy material for China’s air and space industry,Shaanxi Nonferrous Baoti Group supplied 90%Titanium alloy material usage to China’s air and space industry,making it the main supplier of Titanium alloy for China’s new fighters and big planes.