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Table of Content

    25 June 2020, Volume 42 Issue 3
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    SPECIAL ISSUE FOR HIT 100TH ANNIVERSARY
    Microstructural evolution and mechanical performance of high-pressure sintered dense amorphous SiBCN monoliths
    LI Daxin, YANG Zhihua, JIA Dechang, CAI Delong, DUAN Xiaoming, HE Peigang, WANG Shengjin, ZHOU Yu, TIAN Yongjun
    2020, 42(3):  157-169.  doi:10.3969/j.issn.0253-9608.2020.03.001
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    Amorphous SiBCN ceramics are a unique class of structure materials with potential applications as high-temperature heat-resistant structural components owing to their combination of special structure and properties of low specific weight, high specific strength and excellent damage tolerance at elevated temperatures. However, it is still in need for further mechanical properties improvements for actual demands by rational co-design of architecture and chemistry as well as understanding the basic features of morphological/microstructural evolution and failure behavior. Thus in this attempt, to target the dense amorphous Si2ByC2N
    (y=1.5~4) monoliths with high mechanical properties, an attractive way of combinatorial mechanical alloying and high-pressure sintering technique (1 000 oC/3~5 GPa/30 min) was proposed using elemental powders of graphite, hexagonal BN, cubic Si and boron as raw materials. The sintering pressure induced microstructural evolution, phase transformation and thermal stability have been investigated by XRD, SEM, TEM and TG measurements, and mechanical performance, especially the fracture behavior was also discussed in details. Results clearly presented that an increase in sintering pressure promoted the phase transformation of completely amorphous matrix to a hybrid structure of substantial amorphous phases and few nanocrystals of metal c-Si and/or t-BN(C) for some monoliths, implying boron-content depending phase composition. High-pressure sintering effectively promoted the densification leading to free volume annihilation and the river-like fracture boronmorphology occurrence. A monotonous increase of the bulk density, nano hardness and Young’s modulus as a function of the sintering pressure was observed. Under the same sintering conditions, the increase in boron content weakened the mechanical properties and thermal stability of the amorphous Si2ByC2N (y=1.5~4) monoliths. Dense amorphous Si2B1.5C2N monoliths consolidated at 1 000 oC/5 GPa/30 min showed the best
    performance with the bulk density, nano hardness and Young’s modulus obtaining at 2.69 g/cm3, 33.6±2.2 GPa and 414.2±16.5 GPa, respectively.

    Research progress on nontraditional energy field micro-forming
    XU Jie, WANG Chunju, WANG Xinwei, SHAN Debin, GUO Bin
    2020, 42(3):  170-178.  doi:10.3969/j.issn.0253-9608.2020.03.002
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    With the further miniaturization of the manufacturing limit, micro-forming just by loading of the tool (force field) becomes more and more difficult and the limit of the forming scale cannot be broken. Therefore, there is an urgent demand to develop new
    principles, methods and processing technics in micro-forming. Aiming at the fundamental scientific problem of size effects in microforming, nontraditional energy fields such as electric field, electromagnetic field and ultrasonic are introduced to micro-forming technology. The new effects of interaction between energy fields and materials will be used to break through the scale limit and expand the range of materials to achieve multi-scale, multi-material and controllable micro-forming. The development of energy field assisted micro-forming technology will significantly promote the evolution and application of micro-forming technology and becomes an important development trend in the field of micro-nano manufacturing technology.
    De-/hydrogenation mechanism of Mg-based hydrogen storage alloys and their microstructure and property control#br#
    DING Xin, CHEN Ruirun, CHEN Xiaoyu, CAO Wenchao, DING Hongsheng, SU Yanqing, GUO Jingjie
    2020, 42(3):  179-186.  doi:10.3969/j.issn.0253-9608.2020.03.003
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    With the intensified energy crisis and environmental issues, it is of urgent demand to seek for an efficient and renewable alternative to replace the traditional fossil fuels. Hydrogen is considered one of the most promising energy carriers. Hydrogen fuel cell is the main form for the use of hydrogen energy. For fuel cell electric vehicles, the on-board hydrogen storage needs light, compact, and affordable system to replace the compressed hydrogen tanks. Mg-based hydrogen storage material is one of the most promising solid hydrogen storage systems, which has many advantages, but the bottlenecks that hinder its practical application are also difficult to overcome. In this article, the mechanisms for hydrogen absorption and desorption of Mg-based hydrogen storage material are introduced, the constraints of thermodynamic and kinetic properties on its practical applications are expounded, and the causes are further elaborated. The current research methods and progress are summarized, including the common methods of microstructure modification. In further, the development and prospects of Mg-based hydrogen storage material are proposed.
    Micro/nanorobots for targeted therapy
    SUN Mengmeng, XIE Hui
    2020, 42(3):  187-200.  doi:10.3969/j.issn.0253-9608.2020.03.004
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    Micro/nanorobots can be defined as tiny robots with typical dimensions at the micro/nanoscales (several nanometers to hundreds of micrometers), which can convert magnetic, light, ultrasound or other forms of energy into their mechanical motion. The potential capabilities of localized diagnosis and treatment with higher precision and efficiency make the micro/nanorobots a
    promising tool for a variety of biomedical applications. This article reviews recent research progress in preparation, driving of the
    micro/nanorobots, with a special focus on their preliminary applications for directed drug delivery in vivo. In addition, we discuss the challenges of in vivo applications and future trends.
    Micro- and nanotechnology for capturing circulating tumor cells
    LIU Yang, LIU Shaoqin
    2020, 42(3):  201-209.  doi:10.3969/j.issn.0253-9608.2020.03.005
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    Circulating tumor cells (CTCs) have long been considered as one of important causes of cancer metastasis. Precise monitoring of CTCs is crucial for early disease, monitoring the therapeutic outcomes and evaluating cancer prognosis. The most important technical challenges with regard to CTC detection arise from not only the low CTC concentration in bone marrow or blood but also the presence of other cellular contaminants. Therefore, CTC detection requires rapid, extremely sensitive and specific analytical methods. Recently, nanotechnology has emerged as a solution to detect CTCs. This study reviews the recent progress of detection and isolation of CTCs, especially the application of nanostructured materials and microfluidic systems in capture of CTCs.
    Fabrication of nanostructures using AFM mechanical nanoscratching approach and related applications#br#
    WANG Jiqiang, GENG Yanquan, YAN Yongda
    2020, 42(3):  210-220.  doi:10.3969/j.issn.0253-9608.2020.03.006
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    Atomic force microscope (AFM) is a detection device with nano-level precision, which can be utilized to fabricate nanostructures. It has been one of the effective approaches to machine nanostructures and widely used in fields of mechanical engineering, physics, chemistry and biomedicine. Traditional micro/nanofabrication methods were introduced briefly at first. Subsequently, the nanofabrication method based on AFM was described in details and the corresponding advantages were analyzed. The applications of the nanostructures that machined using AFM such as nanochannel and nanodot in fields of nanofluidic and Raman detection were presented. The prospects for future research were put forward at the end of this paper. This review demonstrates the application potential of AFM nanofabrication and provides a necessary nanomachining approach for the research in related fields.
    Field effect transistor in post-Moore era: emerging materials and size limit
    QIN Jingkai, ZHEN Liang, XU Chengyan
    2020, 42(3):  221-230.  doi:10.3969/j.issn.0253-9608.2020.03.007
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    In the post-Moore era, advanced transistor technology in terms of “materials, process and configuration” needs surgently to meet the requirements of power consumption and integration density for large-scale integrated circuit (IC). We herein present a succinct and critical survey of the emerging low-dimensional semiconducting materials for field-effect transistors (FETs), including carbon nanotubes (CNTs), transition metal dichalcogenides (TMDCs), black phosphorus (B-P), tellurene, and related one/twodimensional
    van der Waals heterostructures. Recent research advances of novel FETs below 14 nm node on basis of these materials are also reviewed. In the end, the prospects for future research opportunities as well as accompanying challenges of low-dimensional semiconducting materials are summarized and highlighted.
    Research progress in brazing of fiber-reinforced ceramic matrix composites and metals#br#
    SI Xiaoqing, LI Chun, QI Junlei, CAO Jian, FENG Jicai
    2020, 42(3):  231-238.  doi:10.3969/j.issn.0253-9608.2020.03.008
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    Fiber-reinforced ceramic matrix composites show superior performance over traditional ceramic materials in terms of high temperature serviceability. The components joined with metals have great potential application in high temperature systems, such as aerospace, nuclear energy, chemical industry. The joining technology of fiber-reinforcement ceramic matrix composites and metals has been studied extensively, among which brazing is the best choice. This paper focuses on the challenges and scientific issues of brazing fiber-reinforced ceramic matrix composites with metals. The most widely studied examples of brazing of fiber-reinforced ceramic matrix composites and metals, such as Cf/C, Cf/SiC, SiO2f/SiO2, are discussed. The latest research results of the wetting behavior of braze, the regulation of interface reactions, and the adjustment of joint stress are investigated. The development of reliable joining technology will promote the research and application of more fiber-reinforced ceramic matrix composites with excellent performance.
    Numerical simulation of cough droplets transmission based on Euler-Lagrange method#br#
    WANG Xinzhi, REN Anxing, WU Yongji, WANG Biao, SHI Lei, HE Yurong
    2020, 42(3):  239-248.  doi:10.3969/j.issn.0253-9608.2020.03.009
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    The coronavirus disease 2019 (COVID-19) has spread rapidly in a short period in the whole world. It has been an international epidemic disease. The transmission and spread of respiratory droplets which contain viruses is an important way for the spread of COVID-19. In this paper, numerical investigations of the diffusion process of cough droplets under different conditions such as relatively closed rooms, elevators, high-speed rail cabin, and aircraft cockpit were conducted based on the Euler-Lagrange method.
    The results show that the relatively enclosed space adopts the side-wall convection ventilation or ceiling ventilation modes, which
    reduce the disturbance and residence time of the droplets in the enclosed space. It also inhibits the spread of virus-borne droplets, and enhances the emission of droplets.
    Investigation and genic library construction of microstructure characteristics in asphalt mixtures#br#
    XU Huining, SHI Hao, TAN Yiqiu
    2020, 42(3):  249-261.  doi:10.3969/j.issn.0253-9608.2020.03.010
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    The evaluation and genic library construction of microstructure in asphalt mixtures is the key to understand the service performance of asphalt pavement and improve the durability of materials. This review summarized the study of microstructure characteristics in asphalt mixture. Firstly, the major approaches to capture the microstructure in asphalt mixture were investigated. The digital image processing method based on CCD and X-ray CT technique, and 3D modeling method based on 3D laser scanning technique were studied and the results pointed out the applicability of each approach. Secondly, the study of microstructure characteristics in aggregates and air voids was summarized. The indexes and evaluation methods were detailed introduced. Finally, the genic characteristics of asphalt mixture microstructure were discussed. It was proposed that the genic library construction of microstructure characteristics in asphalt mixture is important to the material study in asphalt pavements.
    Fabrication process of biomimetic layered carbon nanomaterials reinforced metal matrix composites#br#
    CHEN Shipeng, WANG Xiaojun
    2020, 42(3):  262-268.  doi:10.3969/j.issn.0253-9608.2020.03.011
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    The new generation of carbon nanomaterials, represented by carbon nanotubes and graphene, have been the ideal reinforcement for metal matrix composites (MMCs) due to their excellent mechanical properties and unique structure. The strength of metal materials can be improved by means of material compounding. However, this method always compromises strength and toughness, which limits the development of high-performance composite materials and their industrial applications. Inspired by the “brick-and-mortar structure” of nacre in nature, bionic layered structure design is an effective means to solve this problem and fabricate lightweight, high-strength and super-toughness composite materials. In this paper, the fabrication technology of biomimetic layered carbon nanomaterials reinforced metal matrix composites was reviewed and some thoughts were put forward.
    Preparation of light and high-temperature resistant NiAl-based alloy and development of its complex component forming#br#
    WANG Bao, WANG Dongjun, LIU Gang
    2020, 42(3):  269-276.  doi:10.3969/j.issn.0253-9608.2020.03.012
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     NiAl-based alloys are characterized by low density, high modulus and superior oxidation resistance, which are especially suitable for key components working at high temperatures and have broad application prospects in aerospace and other fields. However, as an intermetallic compound, the inherent ductility limitation becomes the technical bottleneck for the forming of complex shape component prepared using NiAl-based alloys. Therefore, it is urgent to develop new technologies of NiAl-based alloy complex component forming. In this paper, the current preparation and forming methods of NiAl-based alloys and their components are
    reviewed, including melting casting, high temperature self-propagating synthesis, powder metallurgy, and reactive preparation method developed in recent years. In addition, the novel reactive preparation-forming method for the potential of complicated thin-walled component manufacturing and the development trend of NiAl-based alloy complex component forming technology are discussed.
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