Alkylene-functionality in bridged and fused nitrogen-rich poly-cyclic energetic materials:Synthesis,structural diversity and energetic properties

From the standpoint of chemical structures,the organic backbones of energetic materials can be classified into aromatic rings,nonaromatic rings,and open chains.Although the category of aromatic energetic compounds exhibits several advantages in the regulation of energetic properties,the nonaromatic heterocycles,assembling nitramino explosophores with simple alkyl bridges,still have prevailed in benchmark materials.The methylene bridge plays a pivotal role in the constructions of the classic nonaromatic heterocycle-based energetic compounds,e.g.,hexahydro-1,3,5-trinitro-1,3,5-triazine(RDX)and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX),whereas ethylene bridge is the core moiety of state-of-the-art explosive 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20).In this context,it is of great interest to employ simple and practical bridges to assemble aromatic and nonaromatic nitrogen-rich heterocycles,thereby expanding the structural diversity of energetic materials,e.g.,bridged and fused nitrogen-rich poly-heterocycles.Furthermore,alkyl-bridged poly-heterocycles highlight the potential for the open chain type of energetic materials.In this review,the development of alkyl bridges in linking nitrogen-rich heterocycles is presented,and the perspective of the newly constructed energetic backbones is summarized for the future design of advanced energetic materials.

Concurrent Material Selection of Natural Fibre Filament for Fused Deposition Modeling Using Integration of Analytic Hierarchy Process/Analytic Network Process

The employment of natural fibres in fused deposition modeling has raised much attention from researchers in finding a suitable formulation for the natural fibre composite filaments.Moreover,selection of suitable natural fibres for fused deposition modeling should be performed before the development of the composites.It could not be performed without identifying selection criteria that comprehend both materials and fused deposition modeling process requirements.Therefore,in this study,integration of the Analytic Hierarchy Process(AHP)/Analytic Network Process(ANP)has been introduced in selecting the natural fibres based in different clusters of selection concurrently.The selection process has been performed based on the interdependency among the selection criteria.Pairwise comparison matrices are constructed based on AHP’s hierarchical model and super matrices are constructed based on the ANP’s network model.As a result,flax fibre has ranked at the top of the selection by scored 19.5%from the overall evaluation.Flax fibre has excellent material properties and been found in various natural fibre composite applications.Further investigation is needed to study the compatibility of this fibre to be reinforced with a thermoplastic polymer matrix to develop a resultant natural fibre composite filament for fused deposition modeling.

Micro/nano Indentation and Single Grit Diamond Grinding Mechanism on Ultra Pure Fused Silica

The existing research about ductile grinding of fused silica glass was mainly focused on how to carry out ductile regime material removal for generating very ＂smoothed＂ surface and investigate the machining-induced damage in the grinding in order to reduce or eliminate the subsurface damage.The brittle/ductile transition behavior of optical glass materials and the wear of diamond wheel are the most important factors for ductile grinding of optical glass.In this paper,the critical brittle/ductile depth,the influence factors on brittle/ductile transition behavior,the wear of diamond grits in diamond grinding of ultra pure fused silica（UPFS） are investigated by means of micro/nano indentation technique,as well as single grit diamond grinding on an ultra-stiff machine tool,Tetraform ＂C＂.The single grit grinding processes are in-process monitored using acoustic emission（AE） and force dynamometer simultaneously.The wear of diamond grits,morphology and subsurface integrity of the machined groves are examined with atomic force microscope（AFM） and scanning electron microscope（SEM）.The critical brittle/ductile depth of more than 0.5 μm is achieved.When compared to the using roof-like grits,by using pyramidal diamonds leads to higher critical depths of scratch with identical grinding parameters.However,the influence of grit shapes on the critical depth is not significant as supposed.The grinding force increased linearly with depth of cut in the ductile removal regime,but in brittle removal regime,there are large fluctuations instead of forces increase.The SEM photographs of the cross-section profile show that the median cracks dominate the crack patterns beneath the single grooves.Furthermore,The SEM photographs show multi worn patterns of diamond grits,indicating an inhomogeneous wear mechanism of diamond grits in grinding of fused silica with diamond grinding wheels.The proposed research provides the basal technical theory for improving the ultra-precision grinding of UPFS.

Comparison of wear behavior of ABS and Nylon6-Fe powder composite parts prepared with fused deposition modelling

Fused deposition modeling(FDM) is one of the latest rapid prototyping techniques in which parts can be manufactured at a fast pace and are manufactured with a high accuracy. This research work is carried out to study the friction and wear behavior of parts made of newly developed Nylon6-Fe composite material by FDM. This work also involves the comparison of the friction and wear characteristics of the Nylon6-Fe composite with the existing acrylonitrile butadiene styrene(ABS) filament of the FDM machine. This Is carried out on the pin on disk setup by varying the load(5, 10, 15 and 20 N) and speed(200 and 300 r/min). It is concluded that the newly developed composite is highly wear resistant and can be used in industrial applications where wear resistance is of paramount importance. Morphology of the surface in contact with the Nylon6-Fe composite and ABS is also carried out.

Study on the Key Influencing Factors in Atmospheric Pressure Plasma Processing of Fused Silica

In order to get ultra-smooth fused silica surface without subsurface damage efficiently, the atmospheric pressure plasma processing( APPP) method has been developed. It is based on chemical reaction between active radicals excited by plasma and workpiece surface atoms,so the subsurface damage caused by contact stress can be avoided and atomic-level precision can be ensured. In this paper,based on the spectral quantitative analysis theory,the influence laws on material removal rate by the key factors of APPP including the flow rate of reaction gases,the input power,the processing distance and time are discussed. In addition,the results that APPP can remove the damaged surface layer and do not introduce secondary damage are proved via the nanoindentation technology.

Methodology for the Determination of Trace and Minor Elements in Minerals and Fused Rock Glasses with Laser Ablation Associated with Quadrupole Inductively Coupled Plasma Mass Spectrometry (LA-Q-ICPMS)

The laser ablation technique, coupled with the use of quadrupole ICPMS equipment, proved a powerful tool for determination of trace elements in minerals. At the University of S?o Paulo, the technique was implemented for the study of minerals such as olivines, pyroxenes and biotites. The main problem to be tackled is the availability of proper multi-element reference materials usually prepared synthetically as glasses with various compositions by NIST and fused rock glasses by the Max Planck Institute (MPI) and USGS (basalts, andesite, quartz diorite, komatiites). The best tested ones are the NIST glasses, with good homogeneity and reliable compositional data for over 40 elements. Results are here presented that test additional RM’s. NIST 612 and 610 were used for calibration purposes. The best results were obtained for rock glasses USGS basalts BHVO-2G, BIR- 1G and BCR-2G (better homogeneity and recommended values). Our contribution tests especially the MPI komatiites glasses GOR-128 and GOR-132G, basalts KL-2G and ML-3BG, andesite StHs-6/ 80G and quartz diorite T-1G, discussing homogeneity issues and providing new data. There is a need for additional preparation of reliable reference materials.

A novel energetic framework with the combination of 5,6-fused triazolo-triazine and nitropyrazole-tetrazole for energy-stability balanced explosive

In recent years,the introduction of fused rings own high density and low sensitivity has promoted the development of energetic materials.However,the development of energetic compounds containing fused and bridged rings by introducing multiple nitrogen heterocycles at different sites of fused rings is still difficult to progress,which seriously limits the emergence of advanced energetic compounds.In this study,a series of energetic materials choosing different nitrogen rich heterocycles at the vacancies of the fused ring,i.e.,neutral compound 5,6 and their ionic derivatives(compounds 7-12)were designed and synthesized.Compounds 5 and 6 were further confirmed by single crystal X-ray diffraction,while the crystal analysis and theoretical calculations were carried out to explore the relationship between crystal structure and physicochemical properties.All of the newly synthesized compounds(5-12)are insensitive to mechanical stimulation(IS>40 J;FS≥342 N)and they own the high detonation velocity(D:8322-9075 m/s).Notably,hydrazine salt 11 own the higher detonation velocity(9075 m/s)and powder density(1.83 g/cm^(3)),but exhibits lower sensitivity(IS>40 J)than the classical energetic compound RDX(8795 m/s,1.80 g/cm^(3),7.5 J).It is obvious that the combination of 5,6-fused triazolo-triazine and nitropyrazole-tetrazole may be a new energetic skeleton for synthesising the heterocyclic compounds with balanced energy-stability.

Effects of Three Silicon-based Raw Materials on Properties and Microstructure of MgO-Al-C Materials

To improve the thermal shock resistance(TSR)of MgO-Al-C materials,three silicon-based raw materials with low expansion coefficients(Si,fused quartz,and SiC)were introduced to the materials,and their effects on the properties of the materials were studied by XRD and SEM.The results show that:(1)the conversion of Si to SiC,SiO2 and forsterite at high temperatures improves the hot modulus of rupture(HMOR),TSR and oxidation resistance of the materials,and the optimal Si addition is 6 mass%;(2)fused quartz improves the TSR of the materials,but its high temperature softening and crystal transformation are not conducive to the HMOR and oxidation resistance of the materials,and the optimal addition is 2 mass%;(3)the SiC addition improves the TSR,HMOR and oxidation resistance of the materials;however,when the SiC addition exceeds 10 mass%,there are more micro-cracks in the materials,decreasing the TSR and oxidation resistance.

Recycled, Bio-Based, and Blended Composite Materials for 3D Printing Filament: Pros and Cons—A Review

In recent years, additive manufacturing (AM), known as “3D printing”, has experienced exceptional growth thanks to the development of mechatronics and materials science. Fused filament deposition (FDM) manufacturing is the most widely used technique in the field of AM, due to low operating and material costs. However, the materials commonly used for this technology are virgin thermoplastics. It is worth noting a considerable amount of waste exists due to failed print and disposable prototypes. In this regard, using green and sustainable materials is essential to limit the impact on the environment. The recycled, bio-based, and blended recycled materials are therefore a potential approach for 3D printing. In contrast, the lack of understanding of the mechanism of interlayer adhesion and the degradation of materials for FDM printing has posed a major challenge for these green materials. This paper provides an overview of the FDM technique and material requirements for 3D printing filaments. The main objective is to highlight the advantages and disadvantages of using recycled, bio-based, and blended materials based on thermoplastics for 3D printing filaments. In this work, solutions to improve the mechanical properties of 3D printing parts before, during, and after the printing process are pointed out. This paper provides an overview on choosing which materials and solutions depend on the specific application purposes. Moreover, research gaps and opportunities are mentioned in the discussion and conclusions sections of this study.

Static Corrosion Rates of Fused-cast AZS Refractory Materials by Molten Glass

In order to investigate corrosive phenomena of fused-cast Al_2O_3-ZrO_2-SiO_2(AZS) refractory materials by molten glass,two types of fused-cast AZS refractory bricks were taken as the interests of the research to study static corrosion rates(mm/d) of the two type materials by molten soda-lime-silica glass at different temperatures(1400,1450 and 1500 *C) and for different isothermal periods(0.5,1.0 and 1.5 d).It was shown that static corrosion rate of each AZS material by molten glass at the triple point developed with raising temperature but slightly decreased with enhancing isothermal period.Based on chemical compositions,microstructures,and corrosive morphologies of AZS refractory materials,the relation between them and static corrosion rates of AZS refractory materials by molten glass was analyzed.

蛋白药降免疫原性改造策略

蛋白药是一种生物活性大分子,可高效治疗多种疾病,近年来在生物医疗领域受到了广泛关注。然而,由于免疫原性的问题,蛋白药很容易被患者的免疫系统快速清除。因此,降低免疫原性对于蛋白药的发展至关重要。讨论了影响免疫原性的主要因素以揭示其背后的机制;综述了多种降免疫原性的策略,包括聚乙二醇化、两性离子化、糖基化以及蛋白质融合等;对未来蛋白药的发展趋势进行了展望。

凹凸棒石增强PA6复合线材制备及3D打印研究

为提高聚酰胺6(PA6)3D打印样件的力学性能,以凹凸棒石(ATP)为增强填料,通过γ-氨丙基三乙氧基硅烷(KH-550)表面改性ATP,采用熔融共混制备PA6/ATP复合材料并通过单螺杆挤出形成3D打印线材,研究了ATP在3D打印过程中的取向行为及其对PA6力学性能的影响,探讨了填料的增强机制。结果表明,适量的ATP能显著提升PA6的力学性能,拉伸强度和杨氏模量分别为73.8 MPa和3.11 GPa,较纯PA6提升35%和27%,ATP在PA6基体中有序取向。

高温热冲击试验对熔融石英陶瓷天线罩材料性能的影响

熔融石英陶瓷材料由于其低膨胀系数、低导热系数、低介电常数及介电损耗、耐腐蚀以及热稳定性好等优点被认为是新型飞行器天线罩的潜在材料。通过对熔融石英天线罩在短时热冲击试验前后的材料性能进行对比,以及对材料性能测试、扫描电镜及XRD开展分析,发现由于热冲击时扩散迁移行为,使熔融石英颗粒熔融连接成片,显著提高了材料的弯曲强度。同时,试验后材料密度、线膨胀系数、比热容、介电性能等未发生明显变化。

耐热含能化合物合成研究进展

从分子设计、合成路线及性能评价等方面简要综述了近十年来报道的热分解温度高于300℃的耐热含能化合物。从分子骨架上看,这些耐热含能分子主要包括单环、稠杂环、联杂环类以及离子盐等。其中,稠杂环和联杂环类是当前耐热含能材料发展的基本特征和主要方向。对含能分子结构与性能的总结分析,构建大共轭和氢键体系是目前提高分子热稳定性的有效策略。合理设计和布局共轭稠杂环和联杂环类骨架,引入氢键系统以及进一步扩大共轭结构将有望实现超高温耐热含能分子构建。

微织构固结磨料抛光轮无水抛光熔融石英光学元件技术研究

抛光是精密光学元件制造的最后一道冷加工工序,当前采用的游离磨料抛光技术蕴含的不可控因素较多,且会在元件表面产生水合层并存在磨料浪费等问题。为了实现可控绿色抛光并确保光学元件达到所需的表面质量要求,固结磨料无水抛光技术以其独特的优势开始得到推广。然而,固结磨料抛光轮在加工时磨损剧烈,耐用性和散热性有所欠缺。因此,在抛光轮上构建螺旋形微织构图案,以压力、转速比、微织构纹理的曲率和条数作为影响因素设计了正交试验,得到了最佳抛光工艺参数。实验表明,与无织构普通抛光轮相比,螺旋形微织构抛光轮能够显著提高砂轮磨损性能,并且在加工过程中能够保证熔融石英元件材料去除率和表面粗糙度收敛。

Experimental Study of Material Removal Process of Fused Silica Glass Using MR Jet Polishing System

Recently,there has been an investigation of polishing processes that has considered new ultra-precision polishing technology for micro parts and optical parts such as those with aspheric and complex shapes.One suitable means of polishing complex shapes is to use a jet of abrasive fluid.However,aerodynamic disturbances and radial spreading are generated by the unstable polishing process of the jet on the surface of the workpiece when it is being polished.A method of jet stabilization has been proposed in which the original nozzle form of a jet of magnetorheological(MR)fluid contains abrasive particles that are magnetized using a magnetic.This paper details the design of an MR jet polishing system that uses an electromagnet,a nozzle,and a hydraulic unit to stabilize a slurry jet based on MR fluid, Second,for silica glass,the polishing spot and section profile are analyzed and the effect of the MR fluid jet polishing process is evaluated.The results of the experiment show that the removal profile is W-shaped and that,in this case,a stable can be proof of a distance of several tens of millimeters from the nozzle.Such results show the possibility of applying the proposed polishing method using MR fluids in ultra-precision micro and optical parts production processes. MR jet polishing shows great potential for use as a new type of precision surface polishing technology.In particular,this is a highly valuable process for the polishing of complex shapes such as micro parts,concaves parts,and cavities.

热熔断体用节银型电接触材料

介绍了热熔断体的基本原理和星状簧片对电接触材料的要求,同时介绍了应用于该领域的电接触材料类型。采用内氧化工艺开发了一种具有良好塑性的AgCuO材料,采用内氧化工艺和热轧复合工艺开发了一种节银型AgCuO/Cu/AgCuO材料,均可满足所有温度等级的有机物型热熔断体的性能要求。

铝质、硅质和镁质耐火材料的X射线荧光光谱快速分析

以Li2B4O7和LiBO2作熔剂,采用熔片法制样,建立了铝质、硅质和镁质耐火材料中MgO,Al2O3,SiO2,CaO,P2O5,TiO2,Fe2O3,MnO,K2O的X射线荧光光谱分析方法。考察了不同样品与熔剂的稀释比例时的玻璃熔片制备的重复性,讨论了烧失量的影响。本方法采用23个国家标准样品或人工合成样品来制作校准曲线,JIS模式理论α系数法校正基体的吸收增强效应,并且用标准样品验证了方法的准确度,标准样品的测定值与标准值非常接近,且有较好精密度。

矾土基电熔锆刚玉和锆莫来石合成料的制备、性能与结构

研究了以高铝钒土为熟料和锆英砂为原料、采用电熔工艺法制备的矾土基电熔锆刚玉和锆莫来石合成料的理化性能、物相组成和显微结构,并用这些合成料制备了Al2O3 -ZrO2 -C试样,检测其常温物理性能、高温抗折强度和抗热震性;同时还与氧化铝基电熔锆刚玉和锆莫来石合成料进行了相应性能的比较。结果表明,矾土基电熔合成料的化学矿物组成、性能和显微结构均与氧化铝基电熔锆刚玉和锆莫来石合成料的相似,而且用其生产的Al2O3 -ZrO2 -C制品的性能也达到了用氧化铝基电熔合成料所能达到的水平,可用于实际生产。

稠杂环化合物在红色磷光铱配合物中的应用

在过去的几十年里,有机发光二极管(OLED)由于潜在的优势,在全彩显示领域引起了高度重视.电致磷光材料因其优异的发光性能,引起了人们广泛关注.对于实际应用的平板显示器,蓝、绿、红三基色是必不可少的.相对于高效的绿光材料,红光磷光材料仍然存在色纯度差、效率低和亮度不足等问题,因此设计合适的红光材料成为具有挑战性的问题.稠杂环化合物因发光量子效率高、发光颜色可调、平衡电荷注入及迁移等优越性能而广泛应用于红色磷光铱配合物.本文综述了近几年稠杂环化合物在小分子、树枝状及高分子红色磷光铱配合物中的应用,阐述了铱配合物分子结构对材料光电性质及器件性能的影响,最后展望了稠杂环化合物在红光磷光材料中的应用前景.