The effect of reactive plasticizer on viscoelastic and mechanical properties of solid rocket propellants based on different types of HTPB resin

Conventional plasticizers deteriorate mechanical and viscoelastic properties of the propellants due to their migration upon aging and long-term storage,which affects reliability and safety properties during exploitation.To address this issue,conventional plasticizer,dioctyl adipate(DOA),is replaced by reactive one,castor oil(CO).In addition,three different types of HTPB were used to obtain propellants with designed viscoelastic and mechanical properties.The CO increased propellants viscosity,without a significant impact on the propellant processability,regardless to the type of prepolymer.Conversely,mechanical properties were different depending on the type of resin,which were further analyzed by gel permeation chromatography(GPC).Addition of CO formed a denser polymer network and shifted T_(g) to higher values,compared to the compositions with DOA.The tensile strength of CO-containing propellants was lower at +20℃ and +50℃ compared to the reference compositions,while the strain at maximum load and strain at break were significantly increased with pronounced plastic deformation,especially for samples at -30℃.The inclusion of CO in the propellants composition gives more room for adjusting a wide range of mechanical properties.

Effect of neutral polymeric bonding agent on tensile mechanical properties and damage evolution of NEPE propellant

Introducing Neutral Polymeric bonding agents(NPBA) into the Nitrate Ester Plasticized Polyether(NEPE)propellant could improve the adhesion between filler/matrix interface, thereby contributing to the development of new generations of the NEPE propellant with better mechanical properties. Therefore,understanding the effects of NPBA on the deformation and damage evolution of the NEPE propellant is fundamental to material design and applications. This paper studies the uniaxial tensile and stress relaxation responses of the NEPE propellant with different amounts of NPBA. The damage evolution in terms of interface debonding is further investigated using a cohesive-zone model(CZM). Experimental results show that the initial modulus and strength of the NEPE propellant increase with the increasing amount of NPBA while the elongation decreases. Meanwhile, the relaxation rate slows down and a higher long-term equilibrium modulus is reached. Experimental and numerical analyses indicate that interface debonding and crack propagation along filler-matrix interface are the dominant damage mechanism for the samples with a low amount of NPBA, while damage localization and crack advancement through the matrix are predominant for the ones with a high amount of NPBA. Finally, crosslinking density tests and simulation results also show that the effect of the bonding agent is interfacial rather than due to the overall crosslinking density change of the binder.

Effect of Water Absorption on the Mechanical Property and Failure Mechanism of Hollow Glass Microspheres Composite Epoxy Resin Solid Buoyancy Materials

To study the water absorption of hollow glass microspheres(HGMs)composite epoxy resin solid buoyancy materials in the marine environment and its effect on the mechanical properties,the water absorption was measured by immersing the material in distilled water for 36 days at ambient temperature and fitted to Fick’s second law.The strength of materials before and after water absorption were tested by uniaxial experiments,and the effects of the filling ratio and water absorption on the mechanical properties of the materials were analyzed and explained.Finally,the failure modes and mechanism of the hollow glass microspheres composite material were explicated from the microscopic level by scanning electron microscope(SEM).This research will help solve the problems of solid buoyancy materials in ocean engineering applications.

Heat-treated microstructure and mechanical properties of laser solid forming Ti-6Al-4V alloy

The effects of heat treatment on the microstructure and mechanical properties of laser solid forming （LSF） Ti-6Al-4V alloy were investigated The influences of the temperature and time of solution treatment and aging treatment were analyzed. The results show that the microstructure of LSFed samples consists of Widmanstatten α laths and a little acicular in columnar prior β grains with an average grain width of 300 μm, which grow epitaxiaUy from the substrate along the deposition direction （27）. Solution treatment had an important effect on the width, aspect ratio, and volmne fraction of primary and secondary a laths, and aging treatment mainly affects the aspect ratio and volume fraction of primary α laths and the width and volume fraction of secondary a laths. Globular a phase was first observed in LSFed samples when the samples were heat treated with solution treatment （950℃, 8 h/air cooling （AC）） or with solution treatment （950℃, 1 h/AC） and aging treatment （550℃, above 8 h/AC）, respectively. The coarsening and globularization mechanisms of a phase in LSFed Ti-6Al-4V alloy during heat treatment were presented. To obtain good integrated mechanical properties for LSFed Ti-6Al-4V alloys, an optimized heat treatment regimen was suggested.

Influence of Ni interlayer on interfacial microstructure and mechanical properties of Ti-6Al-4V/AZ91D bimetals fabricated by a solid–liquid compound casting process

The solid–liquid compound casting of Mg-AZ91D and Ti-TC4 alloys was developed by using pure Ni electro-deposited coating.The pouring temperatures of 660℃,690℃,720℃and 750℃were chosen to investigated the effects of casting temperatures on microstructural evolution,properties,and fracture behaviors of Ni-coated TC4/AZ91D bimetals by the solid–liquid compound casting(SLCC).The scanning electron microscopy(SEM)and the energy dispersive spectroscopy(EDS)results showed that the interfacial zone mainly composed of nickel,Mg_(2)Ni and Mg-Al-Ni in the bimetals cast at 660℃.As the pouring temperature was increased to 750℃,the width of the interface zone,which mainly composed ofδ(Mg),Mg_(2)Ni,Mg-Al-Ni,Mg_(3)TiNi_(2) and Al_(3)Ni,gradually increased.The microhardness tests showed that the micro-hardness of the interface zone was smaller than that of TC4 substrate but larger than that of the cast AZ91D matrix.At the pouring temperature of 720℃,the Ni-coated TC4/AZ91D bimetals had the most typical homogeneous interface,which had granular Mg-Al-Ni ternary phase but no ribbon-like Al3Ni binary phase,and achieved the highest shear strength of 97.35MPa.Meanwhile,further fracture behavior analysis showed that most fracture failure of Ni-coated TC4/AZ91D bimetals occurred at the Mg_(2)Ni+δ(Mg)eutectic structure and Al_(3)Ni hard intermetallic.

Mechanical and electrical properties of Pd-Ru system doped with Zr, Mo, Y

The effect of Zr, Mo, Y dopant on mechanical and electrical properties of Pd-Ru binary alloy was investigated in this work. The alloys were prepared in a vacuum high-frequency melting furnace. X-ray diffraction and metallographic microscope were employed to detect the microstructures of alloys. Electric bridge and eddy current conductive instrument were employed to test the electrical resistivity, and the mechanical properties of alloys were tested by AG-X100KN-type tensile testing machine. The results show that adding rare metal elements into Pd-Ru system could refine the structure effectively and increase the melting point, density, tensile strength, and hardness of alloy, but the elongation and electrical conductivity of alloy decrease. © The Nonferrous Metals Society of China and Springer-Verlag Berlin Heidelberg 2012.

玻璃纤维改性煤基固废胶结充填材料性能研究

基于煤矸石、粉煤灰等煤基固废再生资源利用和胶结充填材料性能优化问题,研究了玻璃纤维掺量、长度和养护龄期对煤基固废胶结材料输送性能和力学性能的影响规律,探讨了玻璃纤维增强机理。实验结果表明:玻璃纤维改性煤基固废胶结材料坍落度随纤维长度和掺量的增大而减小,但均大于200 mm,满足输送性能要求;抗压强度和抗拉强度随纤维长度的增大呈先增高后降低,随纤维掺量的增加而增高的变化规律;当玻璃纤维长度为6 mm、掺量为0.3%时,质量分数为79%的煤基固废胶结材料的综合性能最佳;玻璃纤维改性煤基固废胶结材料水化反应后,生成的针状和团状产物填充了材料细小裂隙且附着于纤维表面,能够有效提高材料的力学性能。

兰炭灰固碳对复合相变储热材料性能的影响

为推动“双碳”战略,促进工业固废兰炭灰的低成本消纳,开发新型绿色低碳复合材料,提出在已有的兰炭灰/硝酸钠复合相变储热材料基础上,利用兰炭灰进行碳捕捉。对固碳前、后兰炭灰及复合相变储热材料的性能进行研究。结果表明:兰炭灰碳捕集的最佳条件为气体组分20%CO_(2)/80%N_(2)、通气时间40 min、加热温度650℃;在最佳实验条件下,兰炭灰的固碳率达到29.27%,所制得的复合相变储热材料固碳兰炭灰/NaNO_(3)的最佳质量比为5:5,在100~380℃储热密度达到288.65 J/g,拥有更好的机械性能、热稳定性及化学相容性。固碳兰炭灰作为骨架材料制备复合相变储热材料具有较好的可行性,为工业固废兰炭灰的资源化利用和碳排放处理提供了新的途径。

典型硫酸盐固废复合胶凝材料制备与微观特性研究

硫酸盐类工业固废造成的环境污染和资源浪费问题引起了国内外学者的广泛关注,当前中国两种典型的硫酸盐类固废(电解锰渣和磷石膏)堆存量巨大,造成严重的环境污染,其无害化与资源化利用刻不容缓。依据电解锰渣、磷石膏两种固体废弃物的特性,利用电解锰渣和磷石膏结合矿渣制备复合胶凝材料,探究了磷石膏和水泥不同掺量对复合胶凝材料硬化体力学性能的影响。通过XRD、SEM和EDS分析了硬化体的物相组成和微观形貌变化特征,同时对硬化体进行毒性浸出测试。结果表明:硬化体各龄期强度随着水泥掺量增加而增大,硬化体各龄期强度随着磷石膏掺量增加而减小。复合胶凝材料较优配合比(质量分数)为电解锰渣为50%、磷石膏为20%、矿渣为30%,水泥外掺12%的硬化体28 d抗压强度为27.1 MPa,硫酸盐固废复合胶凝材料的水化产物主要为水化硅酸钙(C-S-H)凝胶和钙矾石(AFt)。养护至28 d的硬化体浸出液中可溶性Mn^(2+)、NH_(4)^(+)-N、PO_(4)^(3-)和重金属离子浓度稳定后满足GB 8978—1996《污水综合排放标准》的排放要求。

丁羟三组元推进剂的增材制造及性能研究

针对传统浇注成型与直写式3D打印对固体推进剂药浆工艺性能要求相冲突的问题,为实现小型药柱的3D打印,采用添加少量定型助剂(YJ)的方法对丁羟三组元推进剂配方进行改性,对改性前后推进剂的工艺性能、力学性能、燃烧性能和能量性能进行对比分析,并探究了YJ对推进剂性能的影响。结果表明,改性后的推进剂药浆具备可控挤出和室温堆积的流变特性;YJ的加入使得推进剂在20、70℃下的最大抗拉强度分别降低0.1和0.15 MPa,断裂伸长率分别增加了12.7%和9.9%,表明YJ对其力学性能影响显著;此外,实验及理论计算表明,YJ对推进剂的燃烧性能和能量性能影响甚微,燃速最大降低0.24 mm/s,能量变化幅度均在1%以内;表明定型助剂(YJ)的加入不仅使药浆满足3D打印要求,而且对原始推进剂的整体性能没有显著负面影响。

固废基盾构惰性同步注浆材料力学性能及抗水分散性研究

以典型固废矿渣微粉、粉煤灰、硅灰为原料制备固废基盾构惰性同步注浆材料,采用六因素五水平正交试验,开展了注浆材料力学性能及抗水分散性的试验研究。结果发现:增大碱激发剂模数,减小其掺量,则浆液抗压强度下降;水胶比、膨水比对浆液抗动水冲刷能力的影响较大;碱激发剂掺量和水胶比是影响浆液水陆强度比的主要因素。根据正交试验极差分析和综合性能平衡,确定了注浆材料的优选配合比:水胶比1.00,胶砂比0.45,膨水比0.35,减水剂掺量1.5%(质量分数),碱激发剂模数1.6,碱激发剂掺量20%(质量分数),此时注浆材料28 d抗压强度为13.02 MPa,水陆强度比为80.83%,3 h动水冲刷质量损失率为5.62%;并开展了稠度、凝结时间、泌水率和结石率等性能试验,测试指标均达到了活性浆液的要求。以上研究为工业固废在盾构注浆技术领域的应用提供了一定的研究基础和实验依据。

HAN基ECSP凝胶模型的构建与分子动力学模拟

目的从微观分子的角度对硝酸羟胺(HAN)基电控固体推进剂(Electrically Controlled Solid Propellants,ECSP)的性能参数进行模拟与计算。方法利用分子表面静电势(ESP)对HAN分子2种可能的构型进行优化和稳定性分析。通过真空非周期性分子动力学模拟得到聚乙烯醇(PVA)分子稳定构型,并以HAN基ECSP的主要成分按一定比例构建凝胶模型。基于RESP(Restrained Electrostatic Potential)电荷生成更准确的凝胶模型拓扑文件,并进行凝胶模型的分子动力学模拟、模型稳定分析以及模型参数计算。结果凝胶模型总能量相对平均值的周期性波动不超过7%。由于三维PVA链的包裹,H_(2)O分子的扩散系数被大幅削弱。氢键分析和径向分布函数表明氢键键长主要分布在0.2826 nm附近,PVA与H_(2)O间的氢键较少,H_(2)O与HAN、H_(2)O与H_(2)O之间的氢键较多。模型密度为1.405 g/cm^(3),与实验值吻合度高。在283、293、303 K下,HAN基ECSP凝胶模型的拉伸模量依次降低,剪切模量先增后减。在15 K/600 ps冷却速率下,HAN基ECSP凝胶模型的拉伸模量和剪切模量均增大。结论ECSP制备结束后,冷却过程中的环境温度不宜过高,否则容易造成ECSP力学性能的快速下降,快速冷却可以提高ECSP的力学性能。

固体推进剂用新型Schiff碱类高效键合剂的合成及性能表征

为提高丁羟四组元推进剂和CL-20/GAP推进剂的力学性能,解决新的推进剂填料基体界面“脱湿”问题,设计合成了新型Schiff碱键合剂;采用傅里叶红外光谱仪、扫描电子显微镜及万能材料拉伸机等对键合剂的键合效果和推进剂的力学性能进行了表征。结果表明,合成的新型Schiff碱键合剂包含键合剂必备官能团且在AP表面存在明显键合,新型Schiff碱键合剂有望取代有毒MAPO,可明显提高丁羟四组元推进剂的力学性能,使丁羟四组元推进剂常温拉伸强度达到0.7 MPa,常温延伸率大于55%,高温延伸率大于50%,低温延伸率大于60%,并可以明显改善丁羟四组元推进剂的工艺性能;在CL-20/GAP推进剂中,新型Schiff碱键合剂可同时提高推进剂的拉伸强度和延伸率。

复合固体推进剂细观力学性能模拟研究进展

阐述了近年来国内外复合固体推进剂细观力学性能模拟的研究进展,分别从复合固体推进剂细观模型建立和数值模拟分析2个角度分别研究复合固体推进剂的宏观力学性能。介绍了复合固体推进剂细观模型建立的几种方法以及先进的数值模拟技术,综述了机器学习在复合推进剂细观力学性能研究中的应用,并结合当前研究动态和相关技术的进展,对该领域的未来进行展望。分析认为,在细观模型建立方面,分子动力学实现三维RVE计算模型是难点,重点关注含内部损伤的细观本构模型,克服推进剂小变形的不足;在细观尺度数值模拟计算方面,建议在充分包含的细观组成和计算资源成本之间取得平衡,进一步发展能够兼顾计算效率和准确度的复合固体推进剂细观尺度的模拟计算方法。

固体NaOH/Na_(2)SiO_(3)激发矿粉/粉煤灰-炉渣基注浆材料性能研究

以矿粉和粉煤灰-炉渣作为前驱体,其中粉煤灰、炉渣以质量比4:1共同粉磨制备前驱体之一,以NaOH和Na_(2)SiO_(3)配制模数为1.2的固体激发剂,制备碱激发注浆材料。研究粉煤灰-炉渣的掺量、激发剂的掺量(以Na_(2)O计)对注浆材料工作性能和力学性能的影响,并通过扫描电镜(SEM)和能谱分析(EDS)对水化产物进行物理化学表征,使用核磁共振分析注浆材料孔结构特征。研究结果表明:粉煤灰-炉渣掺量为50%的注浆材料的28 d最大抗压强度达31.25 MPa。水化产物主要为C-A-S-H凝胶,浆液结石体内部孔隙主要为胶凝孔(孔径<10 nm)和过渡孔(孔径为[10~100) nm),占比超过90%。

FeS表面改性制备铁基轴承材料的摩擦学性能

以Fe、C混合粉末为原料,分别以FeS、镀镍FeS作为固体润滑剂,通过粉末冶金方法制备铁基轴承材料。研究添加不同质量分数FeS和镀镍FeS对铁基轴承材料微观结构、力学性能和摩擦学性能的影响。结果表明:添加FeS的铁基轴承材料摩擦学性能提高,但是FeS与铁基材料界面结合性差,容易团聚脱落,降低铁基材料的力学性能,不利于材料的减摩耐磨性能提高。表面改性增强了FeS与基体的界面结合,材料的密度和硬度均得到提高。当添加质量分数为8%的镀镍FeS时,所制备的铁基轴承材料力学性能最优,干摩擦条件下,随着载荷增加,含镀镍FeS的铁基轴承材料摩擦系数略微下降,磨损量增加相对缓慢,磨损表面FeS富集,仅存在轻微犁沟,对偶件表面转移膜覆盖程度高、连续性好,材料的减摩耐磨性能好。

粘弹性力学模型在纺织领域的应用现状与发展

粘弹性力学模型广泛应用于表征纺织材料的力学性能,本文从粘弹性力学模型的基本原理、常见力学模型及其在纺织材料中的应用等方面,概述了粘弹性力学模型在纺织领域的发展。结果表明:二元件模型可以简便地反映纺织材料的变形特征;三元件模型在反映纤维的应力松弛及蠕变和纱线的拉伸性能方面具有普适性;四元件模型能精准地预测纺织材料的应力松弛及蠕变规律;此外,还讨论了力学模型在纺织复合材料领域的应用。纺织材料粘弹性力学模型应用现状的研究为纺织材料在多领域的应用提供了参考。

基于机器学习方法的HTPB推进剂力学性能预测研究

固体推进剂中AP颗粒的级配不同会导致力学性能相差巨大,为了探究AP颗粒的粒度值和质量分数对端羟基聚丁二烯(HTPB)推进剂力学性能的影响规律,采用机器学习的方法对推进剂的力学性能进行仿真预测,降低了实验成本并提高了预测效率。首先,对不同级配的HTPB推进剂进行拉伸试验,得到不同温度下抗拉强度和伸长率;其次,以拉伸试验结果为样本进行机器学习,分别构建了反向传播(Back Propagation,BP)神经网络、粒子群算法优化的反向传播(Particle Swarm Optimization Back Propagation,PSOBP)神经网络和遗传算法优化的反向传播(Genetic Algorithms Back Propagation,GABP)神经网络对推进剂的力学性能进行预测。结果表明,力学性能与颗粒级配的内在关系较为复杂,并非简单的线性关系。PSOBP和GABP可以用于预测不同级配下HTPB推进剂力学性能,并且GABP神经网络可以更好地预测推进剂的力学性能变化。

固体添加物粒径对改性双基推进剂力学性能的影响

为研究某型水下武器发射装置中的改性双基推进剂的力学性能,通过调整固体添加物粒径,对比分析不同粒度Al粉和不同粒度SiC/Al_(2)O_(3)的改性双基推进剂力学性能。结果表明,在Al/SiC推进剂中,推进剂的常温抗拉强度和常温最大伸长率随着Al粉粒径的增大呈现先降低后增大的趋势;在不同Al粉粒径下,推进剂的力学性能随SiC粒度变化趋势不同。Al粉粒径为20μm,SiC粒度为W2.5时,低温和常温抗拉强度最大,分别为37.5 MPa和6.58 MPa;Al粉粒径为140μm,SiC粒度为W1.5时,高温抗拉强度最大,为2.22 MPa;加入Al_(2)O_(3)替代SiC后,低温抗拉强度最大为38.3 MPa,比SiC作为弹道稳定剂的推进剂高2.1%,常温抗拉强度最大值高7.1%,高温抗拉强度最大值高4.3%。可见通过调整固体添加物Al粉和SiC/Al_2O_(3)粒径,可实现对改性双基推进剂的力学性能进行局部调控,为水下发射装置的推进剂配方设计提供有效手段。

多元固废基胶凝材料的组成优化及强度形成机理

采用钢渣粉、S95矿粉、粉煤灰和脱硫石膏为原材料,通过单纯形重心方法优化设计制备多元固废胶凝材料,以胶砂抗压、抗折强度试验分析了组成成分对固废胶砂力学性能的影响,采用X射线衍射(X-ray diffraction,XRD)、傅里叶红外光谱(Fourier transform infrared spectroscopy,FT-IR)和热重(thermogravimetric,TG)方法探究了多元固废基胶凝材料强度形成机理。结果表明:多元固废基胶凝材料(SFMD)的最佳掺配比为钢渣粉∶S95矿粉∶粉煤灰∶脱硫石膏=31∶38∶27∶4。多元固废基胶砂试件的力学性能随钢渣粉掺量的增加呈先升高后降低的趋势,S95矿粉对胶砂试件早期强度贡献较大,过量的粉煤灰掺入则不利于胶砂强度的形成。SFMD的红外吸收峰在969 cm^(-1)处出现了C-S-H中Si—O的伸缩振动峰,且SFMD中C-S-H的失重最多,该体系的各组分之间的协同效应较好。此外,脱硫石膏可以促使钢渣粉-S95矿粉-粉煤灰体系的协同水化反应更加彻底,生成提供强度的钙矾石。