Influence of La2O3 on preparation and performance of porous cordierite from rice husk

A porous cordierite was synthesized at 1350 ℃ using rice husk as silica source and pore forming agent, and La2O3 as fluxing agent. The crystal phases of the cordierite were analyzed by X-ray diffraction (XRD) and their microstructures were observed by scanning electronic microscopy (SEM). The flexural strength, porosity and thermal expansion coefficient of the porous cordierite samples were inves- tigated in detail. Results showed that when 5 wt.% La2O3 was added, the flexural strength, porosity and thermal...     

液-液掺杂Mo-La2O3板材的室温力学性能

采用液-液掺杂、粉末冶金的方法制备出Mo-La2O3板坯并轧制成板材,经不同温度退火后进行室温拉伸测试,并利用SEM和EDS等检测手段对其断口形貌、氧化镧含量及分布进行了分析.结果表明:Mo-La2O3板材的延伸率始终高于纯钼板;随着氧化镧含量的增加,Mo-La2O3板材的室温抗拉强度显著提高;而随退火温度的升高,Mo-La2O3板材的断口形貌由韧窝形转变为解理形;氧化镧均匀分布于晶内和晶界,大大降低了晶界上杂质的浓度,抑制了显微空穴和微孔的长大,从而提高了钼板的强度和韧性.     

Effects of lanthanum addition on microstructure and mechanical properties of as-cast pure copper

As-cast Cu-La alloys with La contents in the range of 0–0.32 wt.% were fabricated by vacuum melting method. The effects of La on microstructure and mechanical properties of as-cast pure copper were investigated using optical microscopy(OM), scanning electronic microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD) and tensile test. The results showed that La had obvious effects on the solidification microstructure and the grain refinement of as-cast pure copper. With the increase of La content, the ultimate tensile strength, the yield strength and the microhardness increased gradually, but the elongation increased first and then decreased while La content exceeded 0.089 wt.%. The improvement of mechanical properties was attributed to the effect of grain refinement strengthening, solid solution strengthening, second phase strengthening and purifying. However, excessive adding La would deteriorate the elongation owing to the excessive Cu6 La phases.     

Physicochemical properties of a novel composite polymer electrolyte doped with vinyltrimethoxylsilane-modified nano-La2O3

Nano-La2O3 was modified with the vinyltrimethoxylsilane by hydrolysis and a novel poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) based composite polymer electrolyte doped with the modified nano-La2O3 was prepared by phase inversion method. The physicochemical properties were studied by SEM, FT-IR, XRD, TG and electrochemical methods. The results of FT-IR indicated that the nano-La2O3 was successfully modified with vinyltrimethoxylsilane. The XRD analysis showed that the incorporation of modified nano-La2O3 into the polymer electrolyte membranes could effectively reduce the crystallinity of PVDF-HFP, and the characterizations also suggested that thermal stability and electrochemical stability window could reach to 382°C and 5.1V, respectively; the reciprocal temperature dependence of ionic conductivity followed Vogel-Tamman-Fulcher (VTF) relation, ionic conductivity at room temperature was up to 3.5×10-3S/cm and lithium ions transference number was up to 0.42; the interfacial resistance increased at initial value about353Ω/cm2 and reached a steady value about 559Ω/cm2 after 5d storage at 30°C. The fabricated Li/As-prepared electrolytes/LiCoO2 coin cell showed excellent rate and cycle performances.     

Y含量对Mg-Zn-Y合金显微组织及力学性能的影响

采用金相显微镜、扫描电子显微镜、X-射线衍射仪以及电子万能实验机等设备,研究了Y对Mg-2Zn-xY（X=0、0．5、1、3,质量分数／％）舍金的显微组织及力学性能的影响。结果表明：随着Y含量的增加,合金二次相由Ⅰ相＋W相转变为W相＋H相。舍金力学性能随Y加入量的增加而提高,当加入量为1％时,合金的力学性能达到最佳：抗拉强度达到207MPa,伸长率达到16．9％;而加入量为3％时,综合力学性能又有所下降。     

烧结温度及Y2O3对9Cr-RAFM钢性能的影响

采用粉末冶金技术,以球磨-模压-真空烧结工艺制备2种9Cr-RAFM钢:以0.3%Y2O3(质量分数)为弥散相的ODS 9Cr铁基高温合金和不添加Y2O3的Non-ODS 9Cr铁基高温合金。研究烧结温度及Y2O3对RAFM钢的力学性能和微观组织的影响。研究结果表明:采用球磨-模压-真空烧结工艺制备的ODS合金的综合力学性能高于Non-ODS合金,并且在1 390℃烧结,保温2 h条件下制备的ODS合金具有最佳的综合力学性能(抗拉强度600 MPa,伸长率23.1%)。并对不同球磨时间的合金粉末进行XRD物相分析,用SEM及能谱分析技术研究Y2O3影响RAFM钢的微观组织成分和力学性能的机理。     

CuO-TiO_2对多孔氧化铝陶瓷支撑体性能的影响

以α-Al2O3为骨料,羧甲基纤维素(CMC)为造孔剂和粘结剂,丙三醇为润滑剂和增塑剂,CuO-TiO_2为烧结助剂,采用挤压成形和固态粒子烧结法制备管式多孔氧化铝陶瓷支撑体。通过X线衍射(XRD)、扫描电镜(SEM)、抗折强度测试等,研究CuO-TiO_2对氧化铝陶瓷支撑体的晶相组成与微观形貌、孔隙率、抗折强度、耐酸/碱腐蚀等性能的影响。结果表明:TiO_2与Al2O3固相反应生成Al2TiO5,并生成大量正离子空位而提高扩散系数,促进氧化铝陶瓷的致密化,同时CuO的液相润湿作用使TiO_2的固溶温度降低,生成液相低共熔物CuAl2O4,进而实现低温烧结。当TiO_2与CuO的添加量(质量分数)分别为3%和1.5%、烧结温度为1200℃时,获得孔隙率为33%、抗折强度104.4MPa、酸/碱腐蚀后的质量损失率为0.02%/0.09%的性能优异的管式多孔氧化铝陶瓷支撑体。     

Y2O3含量对钼合金组织和性能的影响

采用粉末冶金方法制备含Y2O3的稀土钼合金,利用金相显微镜、扫描电子显微镜(SEM)、X射线衍射(XRD)、能谱分析(EDS)等手段对钼合金的断裂特征和组织结构进行对比分析,研究稀土氧化物Y2O3含量对钼合金组织和性能的影响.研究表明:添加Y2O3能细化晶粒、改善钼合金的晶粒均匀性和致密度、提高钼合金的性能:拉伸强度和屈服强度随Y2O3含量的增加呈现先增高后降低的趋势,在Y2O3含量为1％时,抗拉强度达511.43MPa,屈服强度456.99MPa,分别是纯钼材料的1.31倍和1.57倍,综合力学性能最佳;在烧结坯中,Y2O3颗粒分布均匀,主要以球形和等轴状形式存在于晶界上.     

胶原蛋白和骨胶在锂电铜箔中的应用

添加不同质量浓度的小分子胶原蛋白（QS）或大分子骨胶（GJ）制备电解铜箔，通过X射线衍射仪（XRD）、扫描电子显微镜（SEM）、微机控制万能试验机等对电解铜箔的相关性能进行了研究。结果表明，与聚二硫二丙烷磺酸钠（SPS）搭配使用时，加入QS或GJ都具有降低铜箔粗糙度和增加光泽的效果，但GJ需要搭配更高浓度的SPS才能发挥此效果；加入QS或GJ都会降低铜箔的抗拉强度， GJ对铜箔抗拉强度的影响相对更小，加入QS后铜箔断裂伸长率有升高的趋势；加入QS或GJ，铜箔毛面均表现出（111）晶面择优取向，晶面（200）和（220）可能与光泽和抗拉强度有关联。     

氧化铝纳米片的气相合成及其力学性能

采用Al片和SiO2粉末为原料,以H2为保护气氛,通过气相沉积方法合成Al2O3纳米片.采用XRD、SEM、TEM和EDS等分析表征手段研究合成的Al2O3纳米片的物相组成、显微形貌和微区成分.结果表明:合成的Al2O3纳米片具有光滑平整的表面,厚度为100～300nm,具有完好的菱方六面体结构.通过纳米压痕仪对合成的...     

Effect of Short Glass Fiber Loading on the Mechanical Behaviour of PA66/PTFE Blend Composites

The polymer blend of Polyamide66 and Polytetrafluroethylene (PA66/PTFE) (80/20 wt.%) were selected for the study. These blends were reinforced with 5, 10, 15, 20, 25 and 30 wt.% of silane treated short glass fibers (SGF) and were prepared by using melt mixing method with the help of twin screw extruder. The mechanical properties such as tensile strength, flexural strength, impact strength were studied in addition to hardness of the blend composites as per ASTM. The results revealed that the addition of SGF into PA66/PTFE blend greatly enhanced the mechanical properties of the polymer blend. The tensile strength and the flexural strength of the blend was almost double than that of the neat blend after reinforcing 30 wt.% of SGF. The addition of SGF into the blend greatly improved the flexural modulus and also the hardness of the blend. The impact strength of the blend decreased initially and then increased after the SGF addition into the blend. The density of PA66/PTFE blend increased after SGF addition. The strain at break almost remained constant but deflection due to bending decreased with the addition of SGF into the studied polyblend. However, the effect of higher loading of SGF on the mechanical behavior of PA66/PTFE blend was greatly appreciable. The fractured surfaces of the specimens were examined by using Scanning Electron Microscope photographs (SEM).     

连续退火的无Si TRIP钢的组织和力学性能

在实验室用Gleeble3500热模拟试验机制备了一种无Si TRIP钢.利用拉伸试验机、扫描电镜、透射电镜、X射线衍射以及热膨胀仪对其力学性能、微观组织和相变规律进行研究,在此基础上分析了贝氏体相变温度和时间对力学性能和残余奥氏体的影响.无Si TRIP钢呈现出良好的整体力学性能,抗拉强度分布在740~810 MPa,延伸率均在25%以上,最高可达32%以上;贝氏体等温温度为420℃时能获得最佳的综合力学性能,抗拉强度随贝氏体相变时间增加而下降,延伸率随之上升,而屈服强度没有显著变化.无Si TRIP制的铁素体晶粒大小约为3~4μm,比含Si TRIP钢铁素体晶粒细小;残余奥氏体的体积分数在8%~10%,比含Si TRIP钢低约3%;420℃保温300 s后贝氏体相变基本结束,而碳的扩散仍然在进行;无Si TRIP钢贝氏体相变速率比含Si TRIP钢快,贝氏体相变总量也更多.      

硅含量对喷射成形铝硅复合材料显微组织与力学性能的影响

利用双喷嘴扫描喷射成形技术制备27%SiAl、42%SiAl、50%SiAl等3种Si-Al合金电子封装材料,并对该材料进行热等静压致密化处理。研究合金沉积态和热等静压态的显微组织,测定合金的热膨胀系数、抗拉强度及抗弯强度,利用扫描电镜研究其断裂机制。结果表明:沉积态Si-Al合金的硅相呈均匀弥散分布。随含硅量增加,合金凝固区间增大,初生硅相的数量增多,平均尺寸增大,由全部颗粒状分布逐渐演化为呈部分颗粒、部分骨架状分布,这种均匀弥散分布的结构有利于降低合金的热膨胀系数。27%SiAl、42%SiAl、50%SiAl合金的热膨胀系数连续可控,室温至200℃分别为14.76×10 6、9.75×10 6、9.29×10 6/K。随硅含量升高,材料的抗弯强度和抗拉强度呈下降趋势。27%SiAl合金的平均抗拉强度和抗弯强度分别达到196 MPa和278 MPa,伸长率为9.5%。42%SiAl与50%SiAl的平均抗拉强度与抗弯强度都接近,分别达到140 MPa及220 MPa,伸长率小于1%。断裂方式由以铝相的韧性断裂为主逐渐转变为以硅相的脆性裂为主。     

高延伸膨胀管用钢的力学性能及微观组织

 采用低碳低合金的成分设计开发了一种新型的膨胀管用钢。经优化的（α+γ）两相区退火工艺处理后,钢材呈现出强度高、延伸性能好、加工硬化能力强、冲击韧性以及高温力学性能优良等特点。常温条件下,该膨胀管材料的抗拉强度超过了700MPa,伸长率超过了40%,强塑积达到了30GPa·%,半厚冲击韧性超过了50J;300℃高温条件下,该类钢仍具有620MPa以上的抗拉强度,40%以上的伸长率以及25GPa·%以上的强塑积。采用SEM和XRD对材料的微观组织进行了表征,该类钢具有马氏体+残余奥氏体+铁素体的多相组织结构形貌。由于弥散分布的小尺寸残余奥氏体在形变过程中的TRIP效应,使得该类钢种在拉伸过程中获得了持续加工硬化的能力,从而获得了强度与塑性的优良结合。     

固相烧结低钨含量W-Ni-Fe合金的微观结构与力学性能

采用固相烧结工艺(1 300℃保温1 h)制备低钨含量(质量分数为60%~80%)的W-Ni-Fe合金,测定合金的抗拉强度、抗压强度和伸长率,利用金相显微镜观察合金的显微组织,并通过扫描电镜(SEM)观察合金断口形貌,研究钨含量对固相烧结W-Ni-Fe合金力学性能与微观结构的影响。结果表明:随钨含量降低,合金的孔隙率和平均孔径减小,抗拉强度增大,伸长率显著提高,抗压强度变化不大。W含量为60%~80%的W-Ni-Fe合金,其孔隙率为17.8%~21.4%,抗拉强度为231~262 MPa,抗压强度2 450~2 550 MPa,伸长率为0.3%~2.3%,压拉比为9.45~11.04,都能满足易碎型穿甲弹弹芯材料的性能要求。     

不同退火温度对Mo-La2O3板材微观组织及力学性能的影响

本文研究了不同退火温度对Mo-La2O3板材微观组织及力学性能的影响。通过金相显微镜、扫描电镜观察了钼合金显微组织及断口形貌,利用透射电镜研究了La2O3对位错分布的影响规律。结果表明,随着退火温度的升高,钼合金晶粒长大,拉伸性能、断裂韧性及显微硬度显著降低。对于退火后的试样,当La2O3粒径较大时,这种颗粒位于晶界处,在颗粒及晶界处形成位错塞积;在退火后的钼合金中,La2O3粒径较小时,绝大多数颗粒位于晶粒内部,位错越过这些颗粒,在晶界或亚晶界上形成位错塞积。     

Effect of neodymium on the as-extruded ZK20 magnesium alloy

The effect of Nd addition on the microstructure and mechanical properties of ZK20 magnesium alloy was investigated by room tensile test, optical microscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) in order to develop a magnesium alloy with higher ductility. Results showed that the crystal grains of as-extruded ZK20+0.5%Nd magnesium alloy were effectively refined, and the alloy exhibited higher strength and ductility, with the UTS of 237 MPa and the elongation of 32.8%, increasing by 5...     

稀土钇元素对SS400钢高温力学性能的影响

为了探究稀土钇元素对SS400钢高温延塑性的影响,在SS400钢中加入稀土钇元素,在Gleeble-1500上进行高温拉伸试验,采用扫描电子显微镜观察断口形貌。试验结果表明：钇元素在SS400钢中以固熔的形式存在,在提高钢的强度的同时也提高了钢的塑性;钇含量在0.001%～0.002 2%时,随着钇含量的增加,SS400钢的抗拉强度提高,其断裂是由Al2O3、MnS夹杂处产生应力集中形成的裂纹源所致。     

Preparation of Cordierite Ceramic Using Mixtures of Ce4+-Modified Amorphous Powder and Oxide Powders

The cordierite ceramic with a high strength and a low thermal expansion coefficient was prepared by using mixtures of Ce4 -modified cordierite amorphous powder and oxide powders of MgO, Al2O3 and SiO2 as starting materials. The transformation procedure of the powders was analyzed by XRD method and the surface morphology of ceramics was examined by SEM method. The flexural strength was measured in a mechanical property testing machine using the Three-Point-Bending sample. Experimental results show that the ceramic added with 10%(mass fraction) of Ce4 -modified amorphous powder is composed of α-cordierite and small amount of CeO2 particles, and has a porosity of 15%(volume fraction) and a flexural strength of 32.6 MPa when sintered at 1350 ℃ for 3 h. It is suggested that this low-cost process is suitable for preparing the components such as supports of vehicle exhaust converters and diesel particulate trappers.     

Microstructure and properties of as-cast Cu-Cr-Zr alloys with lanthanum addition

Cu-0.45Cr-0.2Zr-xLa (x = 0–0.48) alloys were prepared by vacuum casting. The effects of La addition and orientation on the microstructure and properties of the as-cast alloy were investigated by an optical microscope, a scanning electron microscope with an energy dispersive X-ray spectrometer, a tensile testing machine and an electrical conductivity tester. The result shows that the addition of La significantly refines the columnar grainsize and decreases the secondary dendrite arm spacing. Trace addition of La improves the room temperature ultimate tensile strength, elongation and electrical conductivity mainly by purifying during melting and casting. The ultimate tensile strength, elongation and electrical conductivity significantly decrease with the increase of La content due to formation of coarse particles and oxides, which severely harm the performance of the Cu-0.45Cr-0.2Zr-xLa alloys. The Cu-0.45Cr-0.2Zr-0.13La alloy possesses a good combination of room temperature ultimate tensile strength, elongation and electrical conductivity. In addition, room temperature ultimate tensile strength and electrical conductivity along transverse direction of the ingot are higher than that along longitudinal direction, which is mainly ascribed to different distribution of grain boundary and grain orientation.