含团聚硼富燃料推进剂表-界面性能研究

采用界面张力仪和动态接触角方法，测试并计算了不同类型的团聚硼颗粒（ABP）、团聚硼颗粒分别与HTPB、AP、Al粉等填料之间以及含团聚硼颗粒富燃料推进剂的表．界面（多界面）性能，研究了不同类型的团聚硼颗粒对富燃料推进剂药浆流变特性和固化药块的表面微观结构的影响。结果表明，团聚硼颗粒的表面张力（48．96-187．05mN／m）和表面自由能（28．45～199．42mN／m）明显大于AP和Al粉的；TEA和TMP处理的硼粉界面张力（20．27mN／m和21．93mN／m）较小，团聚硼颗粒与HTPB的粘附功较大，表明粘合剂体系与团聚硼颗粒的粘接作用和形成界面浸润能力较强，粘合剂体系在团聚硼颗粒表面的铺展能力较强，从而可明显改善硼粉与粘合剂体系形成悬浮液的流变特性；团聚硼颗粒与填料及HTPB粘合剂体系形成的多界面间的粘附功大于0，表明团聚硼颗粒与推进剂组分之间的粘附作用较强，浸润性较好，容易铺展。从而可明显改善富燃料推进剂药浆的流变特性。

团聚硼颗粒与不同黏合剂的表-界面作用

用DCAT 21型表面/界面面张力仪测试计算了团聚硼颗粒(ABP)、叠氮缩水甘油聚醚(GAP)、端羟基聚丁二烯(HTPB)、高氯酸铵(AP)和铝粉(Al)的接触角和表面自由能。基于所得表面自由能数据,通过计算粘附功和铺展系数,研究了团聚硼颗粒分别与GAP、HTPB、AP和Al粉之间的表-界面作用。结果表明,ABP-GAP和ABP-HTPB界面之间的粘附功(61.38mN/m和60.98mN/m)大于ABP-AP和ABP-Al粉界面的粘附功(51.56mN/m和55.12mN/m),其铺展系数(21.98mN/m和20.27mN/m)大于ABP-AP和ABP-Al粉的铺展系数(7.50mN/m和6.49mN/m),而且团聚硼颗粒分别与GAP、HTPB、AP和Al粉界面之间的相互作用大小顺序依次为:ABP-GAP>ABP-HTPB>ABP-Al粉>ABP-AP。

Microstructures and mechanical properties of Ni-coated SiC particles reinforced AZ61 alloy composites

In order to improve the interface bonding of SiCp/AZ61 composites prepared by powder metallurgy followed by hot extrusion, the electroless plating of Ni-P coating on SiCp was carried out. The influence of Ni coating on microstructure and mechanical properties of the composites was analyzed. The results show that SiC particles distribute more uniformly in the composites after surface Ni plating and there are fewer defects in Ni-coated composite. The Ni coating reacts with the magnesium matrix forming the Mg2Ni interfacial compound layer during the sintering process. The relative density of the composite increases from 97.9% to 98.4% compared with uncoated one and the hardness of the Ni-coated composite increases more rapidly as the volume fraction of SiCp increases. The tensile test results show that the tensile strength increases from 320 to 336 MPa when the volume friction of SiC particle is 9% and the Ni-coated composites have larger elongation, indicating that Ni coating improves the interfacial bonding strength and the performance of the composites. In addition, the fracture properties of SiCp/AZ61 composites were analyzed.

Preparation and characterization of different surface modified SiCp reinforced Al-matrix composites

The effects of SiCp surface modifications(Cu coating,Ni coating and Ni/Cu coating)on the microstructures and mechanical properties of Al matrix composites were investigated.Surface modification of SiC particles with Cu,Ni and Cu/Ni,respectively,was carried out by electroless plating method.SiCp/Al composites were prepared by hot pressed sintering followed by hot extrusion.The results show that the surface modification of SiC particles plays an effective role,which is relative to the type of surface coating,and the interfacial bonding become stronger in the following order:untreated SiCp<Ni(Cu)-coated SiCp<Ni/Cu-coated SiCp.The Ni/Cu-coated SiCp/Al composites exhibit the best comprehensive mechanical properties,with ultimate tensile strength(σUTS)and fracture strain(εf)of 389 MPa and 6.3%,respectively.Compared with that of untreated-SiCp/Al composites,theσUTS andεf are enhanced by 19.3%and 57.5%.

Interface microstructure and mechanical properties of selective laser melted multilayer functionally graded materials

Functionally graded material(FGM)can tailor properties of components such as wear resistance,corrosion resistance,and functionality to enhance the overall performance.The selective laser melting(SLM)additive manufacturing highlights the capability in manufacturing FGMs with a high geometrical complexity and manufacture flexibility.In this work,the 316L/CuSn10/18Ni300/CoCr four-type materials FGMs were fabricated using SLM.The microstructure and properties of the FGMs were investigated to reveal the effects of SLM processing parameters on the defects.A large number of microcracks were found at the 316L/CuSn10 interface,which initiated from the fusion boundary of 316L region and extended along the building direction.The elastic modulus and nano-hardness in the 18Ni300/CoCr fusion zone decreased significantly,less than those in the 18Ni300 region or the CoCr region.The iron and copper elements were well diffused in the 316L/CuSn10 fusion zone,while elements in the CuSn10/18Ni300 and the 18Ni300/CoCr fusion zones showed significantly gradient transitions.Compared with other regions,the width of the CuSn10/18Ni300 interface and the CuSn10 region expand significantly.The mechanisms of materials fusion and crack generation at the 316L/CuSn10 interface were discussed.In addition,FGM structures without macro-crack were built by only altering the deposition subsequence of 316L and CuSn10,which provides a guide for the additive manufacturing of FGM structures.

Investigation of the interfacial properties for CO_2-methanol and CO_2-ethanol mixtures

An equation of state (EOS) applicable for the interfacial properties of CO2-methanol and CO2-ethanol mixtures was established by combining the cross-association EOS and the density gradient theory (DGT). The correlated surface tensions of CO2-ethanol mixtures agreed well with the experimental data. The results illustrated the temperature and pressure dependence of the cross-association between CO2 and alcohol hydroxyls in the whole vapor-liquid surface,and the influence of the cross-association on the calculation of the surface tensions of binary mixtures.

Interface Characteristics of Wood-hybrid Composites

In order to understand the current interface characteristics of wood-hybrid composites, this paper starts off from the concept of composite interface and general theory of interface form, then the inner-surface and microstructure of wood and the interface characteristics of composites, such as wood- inorganic, wood- plastic and wood- metal made by electroless plating technique, are concluded and discussed in detail. Meanwhile, on the basis of that, some points of view about how to develop the wood-hybrid composites interface research in the future are also proposed.

Dynamic effective elastic modulus of polymer matrix composites with dense piezoelectric nano-fibers considering surface/interface effect

Based on effective field method,the dynamic effective elastic modulus of polymer matrix composites embedded with dense piezoelectric nano-fibers is obtained,and the interacting effect of piezoelectric surfaces/interfaces around the nano-fibers is considered.The multiple scattering effects of harmonic anti-plane shear waves between the piezoelectric nano-fibers with surface/interface are averaged by effective field method.To analyze the interacting results among the random nano-fibers,the problem of two typical piezoelectric nano-fibers is introduced by employing the addition theorem of Bessel functions.Through numerical calculations,the influence of the distance between the randomly distributed piezoelectric nano-fibers under different surface/interface parameters is analyzed.The effect of piezoelectric property of surface/interface on the effective shear modulus under different volume fractions is also examined.Comparison with the simplified cases is given to validate this dynamic electro-elastic model.