压坯密度对烧结NdFeB磁体磁性能的影响

采用速凝片（SC）、氢破（HD）和气流磨（JM）工艺制备钕铁硼磁粉,研究了压坯密度、烧结温度对磁体取向度、微观结构和磁性能的影响。结果表明：选择合理的压坯密度（ρx=3．4g／cm3）可以使磁体在模压和液相烧结过程中保持较高的取向度,剩磁提高约2％。在低温度（1055℃）烧结时,可以获得较为理想的显微组织,主相晶粒细小...     

高性能渗碳轴承钢的组织与性能

 研究了热处理工艺对渗碳轴承钢组织、力学性能的影响规律,并探讨了强韧化机制。研究表明,随着淬回火温度升高和回火次数增加以及采用深冷工艺,渗碳轴承钢的强度与硬度增加,冲击韧性值下降。采用910℃淬火和180℃二次回火,轴承钢材料性能可达到硬度HRC452,抗拉强度Rm为1450MPa,屈服强度ReL为1240MPa,AKU为105J,残余奥氏体的体积分数控制在1%以下。试验钢良好的强韧性配合主要来自于晶粒的细化、超细马氏体板条和均匀弥散的细小碳化物的析出;尺寸稳定性的效果主要是残余奥氏体量的控制。     

含Zn3003铝合金的显微组织与性能

采用透射电子显微镜研究了Zn元素对退火态3003铝合金微观组织的影响,并用拉伸试验和电化学极化实验,分别研究了Zn元素对3003铝合金力学性能和电化学腐蚀性能的影响.透射电镜观察和电子拉伸实验结果表明,Zn元素加入3003铝合金,可以细化退火态合金中的析出相,使其分布更加弥散,尺寸更加均匀.Zn元素的加入,可使退火态合...     

储氢合金电极失效的机理分析及研究进展

分析了储氢合金电极失效的四种基本理论,即合金颗粒粉化、元素氧化、吸氢非晶化与释氢晶化、电化学腐蚀机制,并综述其研究进展,提出延缓合金电极容量衰减,改善其循环性能的有效控制途径.     

铝合金板阻尼特性测试方法的分析

为了获得铝合金板即典型结构件的阻尼特性参数——阻尼比ξ值,文中对两种铝合金板件(普通铝和高阻尼铝)采用悬臂梁自由衰减振动法,较简便、准确地测得材料的ξ值。这里详细介绍了该测试试验的理论依据、实施条件、操作步骤和其准确度的仿真验证;并通过对后续试验数据进行处理和对比分析,得出高阻尼铝ξ值为普通铝的1.8倍;且高阻尼铝本身表现出非定值阻尼特性。上述试验结论将为结构减振及优化设计提供借鉴。     

Electrical and thermal characterization of Sm doped ceria electrolytes synthesized by combustion technique

Nanocrystalline samarium doped ceria electrolyte [Ce_0.9Sm_0.1O_1.95] was synthesized by citrate gel combustion technique involving mixtures of cerium nitrate oxidizer (O) and citric acid fuel (F) taken in the ratio of O/F = 1. The as-combusted precursors were calcined at 700 °C/2 h to obtain fully crystalline ceria nano particles. It was further made into cylindrical pellets by compaction and sintered at 1200 °C with different soaking periods of 2, 4 and 6 h. The sintered ceria was characterized for the microstructures, electrical conductivity, thermal conductivity and thermal diffusivity properties. In addition, the combustion derived ceria powder was also analysed for the crystallinity, BET surface area, particle size and powder morphology. Sintered ceria samples attained nearly 98% of the theoretical density at 1200 °C/6 h. The sintered microstructures exhibit dense ceria grains of size less than 500 nm. The electrical conductivity measurements showed the conductivity value of the order of 10⁻² S cm⁻¹ at 600 °C with activation energy of 0.84 eV between the temperatures 100 and 650 °C for ceria samples sintered at 1200 °C for 6 h. The room temperature thermal diffusivity and thermal conductivity values were determined as 0.5 × 10⁻⁶ m² s⁻¹ and 1.2 W m⁻¹ K⁻¹, respectively.     

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 本文全面地研究了淬火温度和回火温度对25CrNiWV钢力学性能及金相组织的影响，确定了此钢种的最佳热处理工艺。     

Mechanical Properties of TC11 Titanium Alloy and Graphene Nanoplatelets/TC11 Composites Prepared by Selective Laser Melting

Titanium matrix composites (TMCs) with excellent mechanical properties, reinforced by graphene, is deemed the lightweight and high strength structural materials. In this study, TC11 titanium alloy powder and graphene nanosheets (GNPs) were used as raw materials, and the composite powder with good uniformity and fluidity was obtained through non-interventional homogeneous mixing by a planetary mixer. The microstructure and mechanical properties of the GNPs-TC11 composites and TC11 alloy were compared. The results showed that the microstructure of TC11 and the composites was acicular martensite α’ phase under the process parameters of 280 W laser power, 1200 mm/s scanning speed, and 0.1 mm hatch spacing. The GNPs in addition, in the composites, reduced the acicular martensite particle size and expanded the proportion of low-angle grain boundaries. The tensile strength and percentage elongation after the fracture of the TC11 titanium alloy were 1265 MPa and 4.3%, respectively. Because of addition of the GNPs, the strength and percentage elongation after the fracture of the composite increased to 1384 MPa and 8.1%, respectively, at a GNPs mass content of 0.2%. The enhancement of mechanical properties can be attributed to grain refinement, dislocation strengthening, Orowan strengthening, and load transfer strengthening.     

PC/ABS合金的力学性能的研究

利用双螺杆挤出机对PC／ABS进行共混,并探讨了PC的质量分数、三种相容剂以及阻燃剂对PC／ABS合金性能的影响。结果表明,拉伸强度随PC含量增加而升高,弯曲强度与弯曲模量则下降,冲击强度则呈现先降后升的趋势;不同相容剂的加入对PC／ABS合金的力学性能均有不同程度的提高;三种阻燃剂中氮磷复合阻燃合金的效果最好。     

高性能CHDI型聚醚聚氨酯弹性体

介绍了CHDI型PTMG聚氨酯的制备工艺和性能，并就其物理机械性能和其它二异氰酸酯聚氨酯作了比较。