聚氨酯在固体推进剂包覆层中的应用

综述了聚氨酯在推进剂包覆层中研究应用的国内外现状并分析了聚氨酯结构特征,讨论了当前聚氨酯包覆层存在的问题,并提出了聚氨酯包覆层的发展方向。     

聚氨酯缓/控释肥制备与膜层表征

利用多亚甲基多苯基异氰酸酯与蓖麻油在尿素表面反应成膜,制备了聚氨酯包覆的尿素缓/控释肥,通过红外光谱和扫描电镜研究了聚氨酯包覆量对膜层结构的影响,采用凯氏定氮法测定了尿素的溶出曲线。结果表明,不同包膜量聚氨酯膜层的反应程度存在差异;随着包膜量的增加,膜层的厚度增加;当聚氨酯的包覆质量分数为3.3%时,25℃下尿素的缓释期达到40～50 d;根据尿素的溶出曲线推测该缓/控释肥的释放为扩散机制。     

聚氨酯包覆层的现状及展望

介绍了国内外聚醚，聚酯型聚氨酯包覆层的研制概况及发展现状，并对深入开展聚氨酯包覆层研究提出了一些个人建议。     

推进剂包覆层用聚氨酯弹性体的合成及应用

利用2,4-甲苯二异氰酸酯（TDI）和液化4,4’-二苯基甲烷二异氰酸酯（MDI）合成聚异氰酸酯,进而合成聚氨酯黏结剂作为某推进剂包覆层的主要组分,使得该包覆层具有良好的力学性能和低烟雾性能等。研究结果表明,TDI和液化MDI的质量分数为70％和30％,合成聚氨酯黏结剂反应温度为80℃,反应时间为30min,固化时间为4～5d较适宜。     

国外无(少)烟聚氨酯包覆层研制概况

介绍了国外近几年在无烟或少烟聚氨酯包覆层研制上所取得的进展,并对在我国开展该类包覆层的研究提出了个人看法。     

国外无(少)烟聚氨酯包覆层研制概况

介绍了国外近几年在无烟或少烟聚氨酯包覆层研制上所取得的进展,并对在我国开展该类包覆层的研究提出了个人看法。     

磷腈阻燃剂合成及其在包覆层中应用研究进展

简述了磷腈阻燃剂的结构特征,并对其阻燃机理进行了分析;综述了磷腈阻燃剂的合成研究进展,着重介绍了不同亲核基团对环状磷腈上的氯原子进行取代反应的合成过程,并对其耐热性和残炭率进行评价;阐述了磷腈阻燃剂在固体推进剂包覆层中的应用,主要包括其对三元乙丙橡胶包覆层、不饱和聚酯树脂包覆层以及聚氨酯包覆层的耐热性能、阻燃性能和耐烧蚀性能研究;提出了磷腈在绝热包覆层中应用的发展方向。     

异氰脲酸酯改性聚氨酯弹性体包覆层研究

为改进固体推进剂包覆层的耐烧蚀性能.以端羟基碳氮杂环氯化聚醚多元醇和改性液体,4,4'-二苯基甲烷二异氰酸酯(L-MDI)为主要原料,设计合成异氰脲酸酯改性聚氨酯弹性体(IMPUE),用于固体推进剂包覆层粘接体系.结果表明,IMPUE具有良好的力学性能,与普通聚氨酯弹性体相比,其热性能、阻燃性能及耐烧蚀性能明显提高,是...     

水性聚氨酯乳液的制备及其在含硝胺推进剂中的应用

以甲苯二异氰酸酯(TDI)、聚氧化丙烯二醇DL-400(Mn=340)、二羟甲基丙酸(DMPA)为主要原料,保持起始时n(NCO)∶n(OH)=1 7∶1,80℃反应1h,1,4 丁二醇(BDO)扩链,水中分散,制得水性聚氨酯乳液PU-1;运用FTIR、1HNMR表征了其结构;采用GPC测定了PU-1的数均相对分子质量Mn为32122,重均相对分子质量Mw为82785,可用作粘附剂。将合成的PU-1乳液应用于复合固体推进剂(NEPE),采用加入十二水硫酸铝钾(明矾)水溶液〔m(明矾)∶m(水)=1∶10〕沉降乳液的方法包覆氧化剂填料黑索今(RDX),使其形成微胶囊;采用SEM观察了包覆结果,发现包覆后的RDX表面圆滑,包覆后的RDX之间流散性较好。通过撞击感度实验,表明包覆后RDX的撞击感度比包覆前下降了28%;通过外壳溶出实验,测得包覆后RDX中聚氨酯包覆层的质量占样品总质量的1 48%,符合军用标准。水性聚氨酯乳液可作为包覆壁材应用于NEPE推进剂中。     

聚氨酯增韧不饱和聚酯包覆层的研究

应用极限力学性能测试、差示扫描量热仪和扫描电镜等方法研究了含双键的聚氨酯(PUUP)对不饱和聚酯(CNVER)的增韧效果。结果表明,PUUP可明显增韧CNVER不饱和聚酯包覆层,随PUUP含量增加,包覆层的拉伸强度显著降低、延伸率明显增大;CNVER包覆层的玻璃化温度为41.1℃,PUUP包覆层的Tg为-4.87℃,两者共混的PUUP/CNVER(70/30)包覆层的玻璃化转化温度介于上述两者之间,为1.4℃;PUUP与CNVER的相容性好,2种聚合物共混后产生微相分离,赋予了材料良好的力学性能,是典型的橡胶增韧塑料材料。     

聚氨酯-硬质合金YG8双层涂层的抗磨蚀性能研究

采用聚氨酯喷涂技术和电火花熔覆技术,在基体铸钢0Cr13Ni5Mo表面制备聚氨酯-硬质合金(YG8)双层涂层,表层为聚氨酯涂层,底层为电火花熔覆层YG8;采用扫描电子显微镜(SEM)观察底层熔覆层与基体铸钢结合面的横截面形貌图,发现熔覆层由白亮层、过渡层组成,表面光亮粗糙,与基体冶金结合;并进行磨擦磨损实验和冲蚀实验。结果表明,双层涂层有较小的摩擦系数,抗冲蚀性是基体抗冲蚀性的3.87倍。该双层涂层兼有软、硬涂层的优点,适用于关键零部件的表面防护和二次修复。     

Fire-performance of a ventilated facade insulated with a B2–classified rigid polyurethane foam

A two-storey test rig was used to investigate how an insulated facade would react to the impingement of a simulated room fire. In particular, whether or not a facade insulated with polyurethane foam would promote vertical flame spread. Wooden cribs weighing 40 kg were used as fire sources. One set of tests was run without any steel cladding to study the behaviour of the polyurethane foam alone. In a wall-configuration test as well as under a conrner-configuration one limited vertical and horizontal flame propagation were found. The degree of damage was to some extent, greater under the corner-test conditions than with the wall tests. A ventilated facade construction with the profiled steel cladding fixed to vertical support-work was used for the second set of tests. In order to simulate repair conditions, the outer metal cladding was completely removed from the lower 1.5 m of the facade. In Both tests a strong chimney-effect behind the cladding was observed. This intensification of the flame impingement led to a flame spread up the top of the facade. The tests indicated that the vertical flame spread would continue unless the method of construction incorporated vertical fire stops.     

Corrosion resistance of AlN and Fe3Al reinforced Fe-based plasma cladding layer in 3.5 wt% NaCl solution

Fe-based cladding layers were prepared via the plasma cladding method using nitrogen as protective and reactant gas. The effects of Al on the phase structure, morphology, composition, and corrosion resistance of the cladding layers were investigated. The based cladding layer consisted of α-Fe, Cr, and small amounts of CrN and Fe_xN, whereas Fe₃Al, Cr₅Al₈ and AlN occurred in the cladding layer with Al. Many AlN particles less than 4 μm in diameter were uniformly distributed in the cladding layer. The nitrides in the cladding layer could accelerate the formation of a passive film and increase the corrosion resistance of the cladding layer. A compact and stable passive film composed of Al₂O₃, Cr₂O₃, α-FeOOH, and Fe₃O₄ formed on the surface of the cladding layer with Al, which is beneficial in protecting the substrate and significantly improving the cladding layer's corrosion resistance.     

氩弧熔覆铁基合金 TiB2-Al2 O3涂层冲蚀磨损性能研究

为提高Q255的冲蚀磨损性能,利用氩弧熔覆方法制备了铁基合金TiB2-Al2 O3涂层。熔覆层显微硬度最高为913．5 Hv0．2是基体硬度的5．9倍;熔覆层的冲蚀磨损性能较基体提高了1．77～4．22倍。熔池组织均匀细小,XRD分析显示,熔覆层由Fe、Al、TiO2、TiB2、Fe2 B、Al2 O3相组成。     

激光熔覆技术制备新型Al-TiC复合涂层的研究

采用预置激光熔覆技术,将Al-Ti-C混合粉末预置于铝合金基体表面,并在氩气保护下,利用YAG激光器实现了在铝合金表面原位形成Al-TiC复合熔覆层。通过改变激光束能量密度和激光束扫描速度等工艺参数,获得了不同工艺条件下的激光熔覆层,并对其显微组织、物相分布及耐磨性能进行比较研究。结果表明由于激光能量密度和激光束扫描速度不同,所形成的熔覆层中TiC的分布状态有很大差别。随着激光能量密度的增大,TiC分布趋于均匀。当激光束扫描速度为2.5mm/s、激光束能量密度为6.09 J/mm2时,熔覆层具有最高的耐磨性能。     

浇注型聚氨酯密封圈的生产工艺

介绍了在聚氨酯密封圈的生产过程中,中间体聚酯和多异氰酸酯的生产反应原理、原料设备、生产的工艺流程、投料配比、工艺操作,预聚体聚氨基甲酸酯和硫化剂按照一定配比浇注成型的聚氨酯密封圈具有优异的综合性能.     

碳化钨对激光熔覆层组织和耐磨性的影响

采用激光熔覆的方法在Q235钢板表面得到熔覆层,研究了激光熔覆后显微组织的变化、表层显微硬度的变化趋势及其原因及熔覆层抗磨损性能提高的幅度。结果表明：添加WC,可使熔覆层组织细化,硬度和抗磨损性能得到不同程度的提高。     

Fabrication of highly dense three-layer SiC cladding tube by chemical vapor infiltration method

Three-layer silicon carbide (SiC) cladding architectures are considered to be promising materials for current light-water nuclear reactors. Herein, a novel processing approach was proposed to fabricate dense three-layer SiC tubes by introducing SiC nanowires (NWs) on the graphite rod, which resulted in change in the valley-peak structure of SiC_f tubular preform. A dense three-layer-NWs SiC cladding tube, consisting of a chemical vapor infiltration (CVI)-SiC inner layer, a CVI-SiC_f/SiC composite layer, and a CVI-SiC outer layer, was obtained through CVI process. Microstructure and hoop strength of the as-obtained three-layer-NWs SiC cladding tube were systematically investigated. By avoiding delamination of the layers and reducing the pores, the three-layer-NWs SiC cladding tube exhibited an average hoop strength of 316.6 MPa with a Weibull modulus of 11.55.     

Effect of WC mass fraction on the microstructure and friction properties of WC/Ni60 laser cladding layer of brake discs

Laser cladding Ni-based composite coating has significant advantages in improving the surface properties of QT500-7. WC/Ni60 composite powders with different WC mass fractions were cladded on the surface of QT500-7. The microstructure and tribological properties of the cladding layer were studied on the basis of optimizing process parameters. The study found that the surface morphology appeared bright white area, bright gray area, dark gray area, and black area. With the increase of WC mass fraction, the types of the cladding layer from bottom to top are gradually enriched, and the types of W-containing carbides produced are also increasing. Meanwhile, the hardness, corrosion resistance, and tribological properties are significantly improved.     

新型金属-陶瓷覆层材料的研究

采用真空液相烧结技术。在钢基体表面制备三元硼化物硬质合金覆层。将三元硼化物硬质合金的优异性能赋予钢基体表面。获得耐磨抗蚀、界面结合强度高的新型硬质合金覆层材料。对三元硼化物硬质合金和钢基体的界面微观结构和界面区元素分布利用SEM-EDS进行分析。发现硬质合金覆层和钢基体之间形成了一个具有一定厚度的过渡层。合金元素浓度没有发生突变。两相之间形成了良好的冶金结合。并对覆层材料的显微硬度、抗弯强度与耐腐蚀性能做了研究。结果表明，硬质合金覆层材料具有较高的显微硬度、界面结合强度和优异的耐腐蚀性能。