烧结温度对SPS制备Ag/La2O3触点材料的影响

采用放电等离子烧结(SPS)技术制备了Ag/La2O3触点材料,研究了烧结温度对其致密度、显微结构及力学性能的影响.结果表明:采用SPS技术制备Ag/La2O3触点材料的工艺中,烧结温度对材料的致密度有着显著的影响,500℃烧结体的致密度最大,达到了97.2%,且试样的抗弯强度最高,约为450MPa;塑性断裂是其主要断裂方式,在不同烧结温度的烧结过程中没有新相出现,La2O3颗粒在银基体中均匀弥散分布.     

Fe2O3微粉添加对MgO CaO系耐火材料烧结性能及 抗水化性能的影响

通过添加Fe2O3微粉的方法,研究了Fe2O3微粉对MgO CaO系耐火材料烧结性能和抗水化性能的影响。试验结果表明,添加Fe2O3微粉可以有效地促进MgO CaO系耐火材料的烧结,抑制其水化速度。当Fe2O3的添加量在0～3%时,随着Fe2O3添加量的增加,耐火材料试样的体积密度先增加后减小,显气孔率则先减小后增加,且两者均在Fe2O3为1%处出现极值。当Fe2O3的添加量在02%～05%的范围时,耐火材料试样的显气孔率和体积密度变化最明显。当Fe2O3添加量为1%时,将试样在温度为60 ℃、相对湿度为75%的条件下水化144 h后,其粉化率仅为146%。
     

pH值对Ni/CuO-ZrO2-CeO2-Al2O3催化剂甲烷自热重整制氢性能影响

采用浸渍-共沉淀法制备了Ni/CuO-ZrO2-CeO2-Al2O3催化剂,其中Ni负载量为10%(质量分数)。采用XRD、H2-TPR等方法表征了催化剂的结构及还原性能,并在固定床微反装置中考察了载体制备的沉淀过程中pH值的改变对Ni/CuO-ZrO2-CeO2-Al2O3催化剂在甲烷自热重整制氢反应中催化性能的影响。研究发现,在反应温度为650℃～850℃范围内,pH值为9制备的Ni/CuO-ZrO2-CeO2-Al2O3催化剂的甲烷转化率最高。由TPR与XRD结果可知,在制备条件中pH值为9的催化剂载体中ZrO2进入CeO2的晶格中,形成更多的CeO2-ZrO2固溶体,使得NiO与载体之间的相互作用增强,从而提高了甲烷的转化率。     

机械合金化制备Al-Al2O3-ZrO2-Y2O3复合涂层及其性能研究

通过机械合金化在室温下于304不锈钢表面成功制得Al-Al2O3-ZrO2-Y2O3复合涂层。通过相关实验分析了复合涂层的组织形貌、显微硬度及高温氧化性能。结果表明:随着球磨时间的增加,涂层厚度先增加后减小;当球磨时间为8h时,涂层最为致密,平均厚度约为200μm;当球磨时间为14h时,涂层部分剥落,涂层厚度减小。涂层的显微硬度明显高于基体,且从表层到基体呈梯度下降,最高显微硬度值达HV0.1525,为基体硬度的2倍多。Al-Al2O3-ZrO2-Y2O3复合涂层的抗高温氧化性能良好。     

电泳沉积法制备固体电解质薄膜的沉积速率和沉积机理

研究了用电泳沉积法的制备含钇８末在悬浮介质中的荷电机理；采用界面移动法测定了８ＹＳＺ粉末在有机悬浮液中的电泳淌度和ξ电势，研究了ξ电势的影响因素；考察了８ＹＳＺ粉末在有机悬浮液中的分散性和稳定性；研究了电泳沉积的动力学规律，确定了电泳沉积过程的速度控制步骤，推导出电泳沉积速率方程。利用重复沉积－烧结法制备的致密化薄膜厚度不２６￣５６μｍ，硬度为４．３３ＧＰａ，在１０００℃时Ｏ＾－２电导率为１２．２     

电泳沉积法制备La2Mo2O9氧离子导体薄膜

采用电泳沉积方法制备陶瓷薄膜过程中,陶瓷颗粒分散良好的稳定悬浮体系是获得高质量薄膜的关键.La2Mo2O9在800℃具有较高的离子电导率,在中温固体氧化物燃料电池中有潜在应用价值.本文采用柠檬酸盐法制备了粒径约为150nm的La2Mo2O9粉体.通过ζ电位的测量,确定了稳定的悬浮体系中丙酮、水、I2和La2Mo2O9粉体的含量,采用电泳沉积方法在La0.8Sr0.2CoO3-x基体上制备了La2Mo2O9薄膜.     

高速电弧喷涂Fe-Al/WC复合涂层在450℃下的热腐蚀行为

采用高速电弧喷涂技术在20G钢基体上制备了Fe-Al/WC金属间化合物复合涂层,利用涂盐热腐蚀试验测试了涂层在450℃下的抗热腐蚀性能。结果表明,Fe-Al/WC复合涂层的热腐蚀动力学曲线近似呈现出抛物线规律;涂层表面的腐蚀产物主要为疏松的Fe2O3,此外,还有少量的Al2O3和FeS,且其分布不均匀;涂层表面优先形成具有保护性的Al2O3膜,保证了涂层具有一定的抗热腐蚀性能;Fe元素的扩散、化学反应及电化学反应综合作用是涂层加速腐蚀的主要原因。     

稳定性油基纳米Fe3O4磁性流体的制备与性能研究

采用化学共沉淀法制备纳米Fe3O4磁性颗粒,在强超声振荡下将其分散在煤油中。采用正交试验设计技术,研究不同用量表面活性剂对Fe3O4磁性颗粒分散的状况以及对饱和磁化强度的影响,通过X射线衍射、红外光谱、VSM振动磁强计对纳米磁流体颗粒的分散稳定性、饱和磁化强度、纯度等进行表征。结果表明:在Fe3+与Fe2+摩尔比约为3∶2、最佳反应温度40～45℃,表面活性剂油酸用量为0.6～0.9ml/g(Fe3O4)的条件下合成的油基磁流体分散均匀、性能稳定;测得的Fe3O4比饱和磁化强度为83.33 A.m2.kg-1,矫顽力为3.40 kA.m-1,具有超顺磁性。     

氧化物添加对BaO-TiO2-Al2O3-SiO2玻璃陶瓷介电性能的影响

采用烧结法制备工艺,成功制备了BaO-TiO₂-Al₂O₃-SiO₂玻璃陶瓷,以钛酸钡体系玻璃陶瓷为基础成分添加不同种类氧化物(Y2O3,Ni2O3,ZrO2),并采用X射线衍射(XRD),场发射扫描电镜(FESEM),精密阻抗分析仪测试仪(LCR)对添加不同氧化物玻璃陶瓷样品的析出相成分、微观结构和介电性能进行表征,研究了氧化物添加对BaO-TiO₂-Al₂O₃-SiO₂玻璃陶瓷性能的影响。研究结果表明:添加不同的氧化物并未改变BaO-TiO₂-Al₂O₃-SiO₂玻璃陶瓷的析出相种类,但能够促进基体中钙钛矿结构钛酸钡结晶相的生成。同时添加不同氧化物后样品的致密度均随烧结温度的升高呈现先增大后减小的变化趋势,在最适烧结温度下,氧化物的添加提高了不同烧结玻璃陶瓷样品的致密度,并优化了样品的介电性能。通过添加不同种类氧化物获得了同时具有高致密度和良好介电性能的玻璃陶瓷成分,当添加0.5%(质量分数)Ni₂O₃时,样品在最佳烧结温度1230°C下烧结获得最大致密度为98.6%,提高了1.65%,样品室温下的介电常数高达1100,提高了139.5%。     

奥氏体耐热不锈钢309S高温抗氧化性能研究

采用不连续称重法测得了奥氏体耐热不锈钢309S在不同温度下的高温氧化动力学曲线,结果表明309S钢高温氧化动力学曲线遵循抛物线规律.利用扫描电镜、X射线衍射和XPS的方法对氧化膜表面的形貌及化学元素沿氧化膜纵深方向的分布情况进行了研究,发现各温度下的氧化膜均均匀覆盖于基体表面;500℃下氧化膜氧化产物表层主要为Cr2O3和Fe2O3,内层主要为Cr2O3和NiO;1 000℃下氧化膜表层主要成分为Cr2O3、NiO、Fe3O4或Fe2O3,氧化膜内层基本不含NiO,主要为Cr2O3、Fe3O4或Fe2O3.     

Influences of Alloying Elements on Oxidation Behavior of Steels and Microstructure of Oxide Scales

In order to figure out the oxidation behavior of steels during heating,five micro-alloyed steels were subjected to continuous and isothermal oxidation using the thermo gravimetric analyzer and the Gleeble-3500thermo-mechanical simulator.The microstructure of oxide scales,especially the thickness fractions of Fe2O3,Fe3O4 and FeO layers,was analyzed using the scanning electron microscope(SEM),electron probe microanalyzer(EPMA)and electron backscattered diffraction(EBSD)techniques.The micro-alloyed steels containing alloying elements(Si,Cr,Ni and Cu)show a higher oxidation resistance compared with the low carbon steel.It is found that alloying elements accumulated at scale/substrate interface during high temperature oxidation.Alloying elements function in two ways in the oxidation of steels:one is enhancing the scale/substrate interface and consequently suppressing the blister of scales;and the other is impeding the outward diffusion of iron cations from substrate to scales,resulting in the decrease of oxidation rate.As the diffusion of iron cations is impeded,the thickness fractions of Fe2O3 and Fe3O4of micro-alloyed steels are more than those of low carbon steels.     

金属基体上YSZ过渡层及YBCO薄膜结构与沉积条件的关系

研究了两种在金属基体（ＨａｓｔｅｌｏｙＣ）上沉积的、以钇稳定的ＺｒＯ２（ＹＳＺ）为过渡层的ＹＢａ２Ｃｕ３Ｏ７－ｙ薄膜结构，并讨论了结构与沉积条件的关系。当沉积速率低时，ＹＳＺ层致密、均匀，存在织构取向，且与基体连接良好；而高速率沉积的ＹＳＺ层疏松，与基体结合差。ＹＢＣＯ薄膜的结构和性能与沉积时的基体温度相关。     

采用TFA-MOD技术在LaAlO3单晶基片上制备YBa2Cu3O7-x涂层导体

三氟乙酸盐-金属有机沉积技术（TFA-MOD）是制备钇钡铜氧涂层导体的有发展前景的方法之一。采用TFA-MOD技术在铝酸镧单晶基片上制备出YBa2Cu3O7-x涂层导体，并对不同烧结温度下制备的薄膜作了分析比较，找到了较为合适的烧结温度。用X射线衍射进行了物相的定性分析，由YBCO薄膜的（103）φ扫描图谱分析了薄膜的外延生长，用原子力显微镜观察了薄膜表面形貌。结果 表明制备出的YBCO薄膜表面均匀致密、无明显裂纹、有较强的（001）衍射峰。     

CrO_3对SHS重力法制备薄壁管内衬涂层质量的影响

采用SHS重力法,以Al-Fe_2O_3为反应体系,SiO_2、CrO_3为添加剂,对小直径薄壁陶瓷内衬管的制备工艺进行了研究。结果表明:在没有添加CrO_3情况下,陶瓷层中含有Al2O3、Al6Si2O13、Fe Al_2O_4和Fe_2SiO_4等相;添加CrO_3以后,FeAl_2O_4和Fe_2SiO_4衍射峰消失。当CrO_3的添加质量分数为6%时,基体表面出现微熔,与陶瓷层结合最为紧密,涂层与基体的结合界面属于"机械锚固",此时显气孔率出现极小值,致密度最高;而后,随着CrO_3添加量增加,显气孔率逐渐升高,体积密度逐渐下降,当CrO_3添加质量分数为10%时,钢管发生了局部熔穿,获得的涂层气孔较多,结构疏松,质量较差。     

Gd2O3-HfO2栅介质薄膜的外延制备及Ge-MOS电学特性分析

以Gd2O3-HfO2( GDH)固溶氧化物作为靶材,采用脉冲激光沉积技术(PLD)在Ge(100)衬底上制备了GDH高k栅介质外延薄膜,其外延生长方式为“cube-on-cube”,GDH薄膜与Ge(100)衬底的取向关系为(100)GDH∥(100)Ge和[110] GDH∥[110]Ge.通过反射式高能电子衍射(RHEED)技术研究了激光烧蚀能量和薄膜沉积温度对薄膜晶体结构的影响,分析了二者与薄膜的取向关系,激光烧蚀能量对薄膜取向影响更为显著.得到较优的GDH外延薄膜沉积工艺为:激光烧蚀能量为3 J·cm-2、薄膜的沉积温度为600℃.用磁控溅射制备了Au/Ti顶电极和Al背电极,其中圆形的Au/Ti电极通过掩膜方法获得,直径为50μm.采用Keithley 4200半导体测试仪对所制备Au/Ti/GDH/Ge/Al 堆栈结构的Ge-MOS原型电容器进行电学特性分析,测试条件为:I-E测试的电场强度0～6MV·cm-1,C-V测试的频率300 kHz～1 MHz,结果表明,厚度为5nm的GDH薄膜具备良好介电性能:k-28,EOT ～0.49 nm,适于22 nm及以下技术节点集成电路的应用.     

La_2O_3对微波烧结Cu_(20)Fe_(80)合金组织性能的影响

采用机械合金化和冷压微波烧结法制备了Cu_(20)Fe_(80)合金,研究了La_2O_3添加对Cu_(20)Fe_(80)合金组织性能的影响,利用扫描电子显微镜和X射线衍射仪等设备观察和分析Cu_(20)Fe_(80)合金组织形貌和相组成,并测定了合金的致密度和硬度。结果表明:Cu_(20)Fe_(80)合金粉体呈层片状,随La2O3质量分数的增加,合金粉体得到细化,机械合金化程度增强;Cu_(20)Fe_(80)合金粉体的冷压压坯组织呈层片状,随La_2O_3质量分数的增加,压坯致密程度和成型性提高;微波烧结后组织呈现层片状,随La_2O_3质量分数的增加,空隙先减少后增加,烧结组织致密度和硬度先提高后减小;综合分析,La_2O_3最佳添加量为0.2%。     

O2/N2与O2/CO2气氛下Fe2O3与K2CO3对无烟煤催化燃烧反应性的影响

利用综合热分析仪研究了O2/N2与O2/CO2气氛下Fe2O3与K2CO3对无烟煤催化燃烧反应性的影响。结果表明,在O2/CO2气氛下,Fe2O3与K2CO3均可以催化无烟煤粉的燃烧,但其催化作用要弱于O2/N2气氛,且在低氧气浓度的O2/CO2气氛下对Fe2O3与K2CO3的抑制作用大于高氧气浓度。氧气浓度为20%~80%时,K2CO3在O2/N2气氛下催化煤粉前期燃烧使燃烧由反应控制转变为扩散控制,Fe2O3则只在氧气浓度为20%时能改变煤粉前期燃烧的控制步骤;而Fe2O3与K2CO3在O2/CO2气氛下均只能在氧气浓度为20%时改变煤粉前期燃烧的控制步骤,由反应控制转变为扩散控制。     

Growth and interface of amorphous La2Hf2O7/Si thin film

Amorphous La2Hf2O7 thin films were deposited on Si(100) substrate by pulsed laser deposition (PLD) method under different con-ditions. The interfacial states of the La2Hf2O7/Si films were studied by synchrotron X-ray reflectivity (XRR) and X-ray photoelectron spec-troscopy (XPS). When grown under vacuum condition, silicate, silicide and few SiOx were formed in the interface layer. However, the Hf-silicide formation could be effectively eliminated by the ambient oxygen pressure during film growth. The result revealed that the La2Hf2O7/Si interlayer was intimately related with growth condition. Insufficient supply of oxygen would cause Hf-silicide formation at the interface and it could be most effectively controlled by the ambient oxygen pressure during film growth.     

Formation of Nanocrystalline Structure of TaSi2 Films on Silicon

The nanocrystalline structure and mechanical properties of TaSi₂ films deposited by sputtering of TaSi₂ target have been investigated by x-ray diffraction, cross-sectional transmission electron microscopy (TEM), four-point electrical resistance measurement, and cyclic depth-sensitive nanoindentation. The purpose of this work is to study the formation of nanocrystalline structure in TaSi₂ films on a silicon substrate. As revealed, a decrease in the deposition rate leads to an increase in the O and C impurity content in the films. Contamination of the film by O and C atoms during a low-rate deposition causes the formation of an amorphous phase in the deposited films. Upon annealing, the amorphous structures crystallize into mixtures of disilicide and a small amount of polysilicide, i.e. TaSi₂ and Ta₅Si₃, respectively. After annealing at 970 K, the formation of a nanocrystalline structure with a grain size about 10 nm takes place in the film produced at a deposition rate of 0.2 nm/sec. The formation of a nanocrystalline structure changes drastically the mechanical properties of the film. The nanohardness and elastic modulus increase significantly, and the film becomes brittle and overstressed. After deposition in the film produced at the 1 nm/sec deposition rate mainly Ta disilicide and the amorphous phase are observed. After annealing, the amorphous phase near the Si substrate coexists with column-shape grains of Ta disilicide of size 150 × 500 nm. The annealed thin film becomes nonuniform in thickness. The nanohardness and elastic modulus increase.     

Influence of La2O3 on crystallization behavior of free-fluoride mould flux and heat transfer of slag films

In order to research the influence of La2O3 on crystallization behavior of free-fluoride mould flux and the heat transfer of slag film,free-fluoride mould flux with various La2O3 content were investigated by using self-made mould simulator,comprehensive thermal analyzer and SEM-EDS.With the increase of La2O3 content from 0% to 20%,the crystallization ratios of mould flux films were improved from 2% to 90% and the thicknesses of films were also enhanced over two times.Moreover,crystallization temperature was greatly raised and its increasing extent reached 100 oC.It could also decrease the melting temperature of casting powder about 50 oC.However,the undissolved La2O3 particles appeared in slag film if the ratio of La2O3 in free-fluoride mould flux was much too high.