Dy,Nd掺杂对（Sr，Ba，Ca）TiO3基压敏陶瓷性能的影响

采用常规固相反应法制备（Sr,Ba，Ca）TiO3基压敏陶瓷，在Mn作为受主掺杂元素，Nb^5＋离子取代Ti^4＋离子的前提下，用Dy^3＋或Nd^3＋离子取代Sr^2＋离子，并系统研究掺杂Dy或Nd对（Sr，Ba，Ca）TiO3基压敏陶瓷性能和结构的影响。结果表明：掺杂Dy或Nd可以制备出Ⅴ10mA=4．16-39．37V，α=2．45～3，23的压敏陶瓷。     

微波烧结制备高电位梯度ZnO压敏电阻的研究

利用微波烧结技术制备高电位梯度ZnO压敏电阻.将ZnO和PbO、B2O3、Co2O3、MnO2粉体按照化学计量比混合,将所得的粉体经干燥、650℃预烧、700～900℃烧结、成型;对比了不同温度下常规烧结和微波烧结对ZnO压敏电阻电性能的影响,同时研究了烧结温度对ZnO压敏电阻电性能的影响;并采用SEM和XRD对烧结试样结构进行表征.结果表明,微波烧结所制备样品内部的晶粒生长均匀,平均粒径为200～500 nm,试样压敏电压为800～1000V/mm,试样漏电流为80～120μA.     

高能球磨掺杂氧化物粉体和压敏陶瓷粉体对氧化锌压敏陶瓷性能的影响(英文)

采用高能球磨掺杂氧化物粉体和压敏陶瓷粉体2种不同制备技术制备ZnO-Bi2O3压敏陶瓷,通过扫描电镜和X-射线衍射对其显微组织和相成分进行分析,探讨不同高能球磨制备技术对氧化锌压敏陶瓷电性能和显微组织的影响。结果表明:压敏陶瓷粉体高能球磨是制备高性能氧化锌压敏陶瓷的一种优异的技术,在1000°C下烧结3h,压敏陶瓷的电位梯度为617V/mm,非线性系数为57;压敏陶瓷的致密度高达95%,显微组织均匀、致密;高能球磨压敏陶瓷粉体可细化晶粒,增强烧结驱动力,加速烧结过程,降低烧结温度。     

高温固相合成制备高纯Cr_2AlC的研究

采用Cr粉、石墨粉、Al粉为原料,通过高温固相反应法制备了高纯Cr_2AlC材料。用X射线衍射仪和扫描电镜研究了试样的物相组成及微观结构,用K-值法估算出Cr_2AlC的纯度。结果表明:合适的原料比、适宜的烧结温度能提高所得粉体中Cr_2AlC的含量。通过高温固相合成法,在烧结温度1300℃时,原料配比Cr:Al:C=2:1.2:1的试验条件下得到的Cr_2AlC试样,纯度为98.19%。     

镍酸镧陶瓷靶材的制备工艺北大核心CSCD

采用固相反应法制备镍酸镧(LaNiO3)粉体,利用常压烧结法烧结LaNiO3陶瓷靶材。探索了制备LaNiO3陶瓷粉体的工艺条件;利用X射线衍射(XRD)和扫描电镜(SEM)分析了固相反应热处理工艺及烧结工艺对LaNiO3陶瓷粉体及靶材的相组成及微观形貌的影响。结果表明:在氧气气氛中,900℃下煅烧10 h可获得纯度较高、晶粒细小的LaNiO3粉体;烧结温度为1100℃保温4 h时,获得了比较致密且晶粒分布均匀的LaNiO3陶瓷靶材,同时电阻率达到了0.52 mΩ·cm。     

掺铁SnO2陶瓷及薄膜制备研究

采用PVA-粉体复合法制备SnO2粉末前驱体,固相反应法制备掺铁SnO2陶瓷,通过XRD、SEM和EDS分析表征材料的晶体结构、表面形貌和Fe元素的微区分布状态.考察了烧结温度和Fe掺杂量对制备工艺条件、陶瓷晶体和晶界结构的影响.结果表明,Fe元素的引入,有效降低了SnO2陶瓷的烧结温度,使主晶相和晶界的显微组织清晰;在最佳烧结温度1350℃下制备出了无杂相、致密的,且掺铁量为8at％的SnO2陶瓷;在衬底温度650℃、镀膜氧压4Pa的条件下制备出了质量较好的掺铁SnO,薄膜.     

掺杂TiO_2对ZnO压敏陶瓷电学性能的影响

以ZnO粉末为主要原料,以TiO2、Bi2O3、MnO2、Co2O3、Sb2O3为组元,在常规电子陶瓷生产工艺下制备低压化ZnO压敏陶瓷。将掺杂TiO2的陶瓷片与未掺杂TiO2的陶瓷片进行对比分析,确定最佳掺杂量。采用能谱仪分析瓷片的微区成分,采用SEM观察瓷片断口形貌,利用压敏电阻直流参数仪测量瓷片的电学性能。研究结果表明,瓷片内部主要存在富Bi晶界、Bi贫化晶界和晶粒直接接触晶界;TiO2对ZnO晶粒有助长作用,不掺杂纳米TiO2陶瓷是11.4μm,掺杂纳米TiO2高达30.5μm;当TiO2掺杂量为1.5%mol时瓷片电学性能较优,即压敏电压为31.2 V/mm、漏电流为0.028 m A及为非线性系数为20.1。     

热压烧结GZO陶瓷致密化与固相反应

以Ga_2O_3掺杂量(质量分数)为3%的ZnO-Ga_2O_3混合粉体为原料,采用热压烧结法制备GZO陶瓷。通过XRD、SEM、阿基米德排水法和四探针法对烧结试样的物相组成、显微结构、密度和电阻率等进行分析表征。结果表明:外加压力能有效降低GZO陶瓷烧结致密化温度;当外加压力为18 MPa时,随烧结温度升高,烧结体的密度和电导率增大;当烧结温度达1150℃时,烧结体密度和电导率达到最大值;但当烧结温度继续增大时,由于晶粒粗化和Zn元素挥发导致试样中气孔长大,试样致密度与导电性呈下降趋势。此外,ZnO-Ga_2O_3混合粉体在烧结温度较低时(1050℃),Ga_2O_3与ZnO固相反应生成ZnGa_2O_4立方尖晶石相;随着烧结温度升高,ZnGa_2O_4将与ZnO继续反应,生成与ZnO六方纤锌矿结构呈共格关系的复杂化合物ZnxGa_2O_(x+3),并且化合物化学式中x值随着烧结温度的升高而增加,化合物晶体结构逐渐接近ZnO六方纤锌矿结构。     

制备工艺对偏铝酸锂（γ-LiAlO2）陶瓷性能的影响

采用固相法合成粉体，冷等静压成型，保护烧结制备出了单一相的γ—LiAlO2陶瓷试样。采用激光粒度仪，XRD和电子拉伸机等分别测定了粉体的粒度、相组成和试样的抗压性能等。主要研究了粉体合成以及工艺因素对烧结后γ—LiAlO2陶瓷试样的相对密度、气孔率和抗压强度等性能的影响。研究结果表明：原始粉料的粒度和分布对烧结影响很大：成型压力为300MPa，烧结温度1400℃保温6h所得试样的性能较佳。     

CuO掺杂(Ba0.7Ca0.3)TiO3-Ba(Zr0.2Ti0.8)O3无铅压电陶瓷的研究

用传统固相反应法在不同温度下烧结制备了不同含量CuO掺杂的0.45(Ba0.7Ca0.3)TiO3-0.55Ba(Zr0.2Ti0.8)O3(BCZT45)无铅压电陶瓷,研究了CuO掺杂对BCZT45陶瓷微观形貌、相结构、介电和压电性能的影响。X射线衍射(XRD)结果表明所有陶瓷均形成了钙钛矿结构,Cu2+固溶进入BCZT45晶格,Cu2+部分取代Ti4+引起晶格畸变。加入CuO改善了BCZT45陶瓷的烧结性能,降低了烧结温度,使陶瓷在1350℃即可烧结,提高了陶瓷密度。随着CuO含量的增加,陶瓷的介温曲线向低温方向移动。掺杂少量CuO后,BCZT45陶瓷的压电常数增大,随着CuO掺杂量的增加又急剧降低。掺杂CuO含量为0.25mol%的BCZT45陶瓷具有最好的电学性能:压电常数d33=340pC/N,室温介电常数εr=3147,介电损耗tanδ=0.025。     

Nd2O3对氧化锌压敏阀片压敏电位梯度与显微组织的影响

研究了微量Nd2O3添加剂对氧化锌压敏阀片的压敏电位梯度的影响，并对其微观组织进行了分析研究，从理论上探讨了Nd2O3影响氧化锌压敏阀片压敏电位梯度与组织的机理。研究结果表明，在0m01％～0．04mol％成分范围内，随着Nd2O3含量的增加，氧化锌压敏阀片的压敏电位梯度明显提高；当Nd2O3含量超过0．04mol%时，随其含量的增加，氧化锌压敏阀片的压敏电位梯度又呈降低趋势。其原因是Nd2O3加入到氧化锌压敏阀片中，使晶粒尺寸减小所致。     

Degradation characteristics of low-voltage ZnO varistor manufactured by chemical coprecipitation processing

The chemical coprecipitation processing has been developed to manufacture low-voltage ZnO varistor. The emphasis of the process is mainly on improving the stability against AC degradation stress and pulse degradation so as to obtain high quality component. It was found that the higher electrical field (E_b = 87.5 V/mm) and nonlinear coefficient ( = 32.5) can be obtained on the sintered sample prepared with this method compared with sample of identical overall composition prepared by conventional ceramic processing route. The improvement in electrical properties may be explained by the homogeneous distribution of various dopant in the mixed powder and the chemically more uniform structures.     

Microstructure and electrical properties of Lu2O3-doped ZnO-Bi2O3-based varistor ceramics

Lu2O3-doped ZnO-Bi2O3-based varistor ceramics samples were prepared by a conventional mixed oxide route and sintered at temperatures in the range of 900-1 000°C,and the microstructures of the varistor ceramics samples were characterized by X-ray diffractometry(XRD)and scanning electron microscopy(SEM);at the same time,the electrical properties and V-I characteristics of the varistor ceramics samples were investigated by a DC parameter instrument for varistors.The results show that the ZnO-Bi2O3-based varistor ceramics with 0.3%Lu2O3(molar fraction)sintered at 950°C exhibit comparatively ideal comprehensive electrical properties.The XRD analysis of the samples shows the presence of ZnO,Bi-rich,spinel Zn7Sb2O12 and Lu2O3-based phases.     

Effect of SnO2 doping on microstructural and electrical properties of ZnO-Pr6O11 based varistor ceramics

ZnO-Pr₆O₁₁ based varistor ceramics doped with 0-2.0 mol% SnO₂ were fabricated by sintering samples at 1300 °C for 2 h with conventional ceramic processing method. X-ray diffraction analysis indicated that the doped SnO₂ reacted with praseodymium oxides during sintering, generating Pr₂Sn₂O₇ phase. Through scanning electron microscopy, it was found that the doping of SnO₂ played a role against the growth of ZnO grains. Capacitance-voltage analysis revealed that the doped SnO₂ acted as a donor in the varistor. The measured electric-field/current-density characteristics of the samples showed that the varistor voltage increased with the increase of SnO₂ doping content, when the SnO₂ content was no more than 1.0 mol%; with the SnO₂ content up to no more than 0.5 mol%, the doping of SnO₂ could increase the nonlinear coefficient; but, when the SnO₂ doping content was further increased, the nonlinear coefficient and varistor voltage of the samples decreased, and the leakage current increased.     

Electrophysical properties of ceramic–polymer composite films as function of sintering temperature

The effect of changes in sintering temperature on electrical properties and microstructure of ZnO–polyaniline– polyethylene composite ceramics, prepared in disk form at the pressure of 60 MPa and at five different temperatures, has been investigated. Increasing sintering temperature from 30 to 120 °C noticeably reduces breakdown voltage from 830 to 610 V. Further increase in sintering temperature causes breakdown voltage to increase. Interface voltage barrier height behaves differently when sintering temperature increases, which is in contrast to breakdown voltage behavior. These samples have a very low leakage current, a factor which indicates low degradation. Then again, the higher the sintering temperature gets, the less the nonlinear coefficient becomes. In addition, each sample has hysteresis which decreases through increase of sintering temperature up to 120 °C. Further increase in sintering temperature, however, causes the hysteresis loop to spread. Regarding UV spectra of the samples, it is revealed that there are three impurity levels whose behaviors against sintering temperature are subtractive. Analysis of composite samples by scanning electron microscopy indicates that their microstructure consists of grains and grain boundaries. Resistivity of grain boundaries is the main responsible factor for these changes in varistor characteristic as a function of sintering temperature.     

Microstructure and electrical properties of Y(NO3)3·6H2O-doped ZnO-Bi2O3-based varistor ceramics

Y(NO₃)₃·6H₂O-doped ZnO-Bi₂O₃-based varistor ceramics were prepared using a solid reaction route. The microstructure, electrical properties, degradation coefficient (D_V), and dielectric characteristics of varistor ceramics were studied in this paper. With increasing amounts of Y(NO₃)₃·6H₂O in the starting composition, Y-containing Bi-rich, Y₂O₃, and Sb₂O₄ phases were formed, and the average grain size decreased. Results also showed that with the addition of 0.16 mol% Y(NO₃)₃·6H₂O, Y(NO₃)₃·6H₂O -doped ZnO-based varistor ceramics exhibit comparatively better comprehensive electrical properties, such as a threshold voltage of 425 V/mm, a nonlinear coefficient of 73.9, a leakage current of 1.78 μA, and a degradation coefficient of 1.7. The dielectric characteristics and lightning surge test also received the same additional content of Y(NO₃)₃·6H₂O. The results confirmed that doping with rare earth nitrates instead of rare earth oxides is very promising route in preparing high-performance ZnO-Bi₂O₃-based varistor ceramics.     

喷射电沉积技术制备Co-Cr_3C_2复合镀层的工艺优化

为提高微米级硬质陶瓷颗粒在金属基复合镀层的含量,制备性能优异的防护性镀层,采用喷射电沉积的方法在直流电压下制备了Co-Cr_3C_2复合镀层,利用控制变量法探讨了电流密度、固体颗粒用量、镀液流量以及喷枪移动速度等对镀层中颗粒含量及镀层性能的影响,并分析了各因素的影响机理。同时,分别采用能谱仪、显微硬度计和摩擦磨损试验机对复合镀层的成分、硬度和摩擦因数进行分析,最终确定了制备该复合镀层的较优工艺参数。结果显示:喷头移动速度对颗粒复合量的影响最为显著;颗粒复合量越大,复合镀层硬度越高、摩擦因数越低;在较优工艺参数下制备的Co-Cr_3C_2复合镀层的Cr_3C_2颗粒含量高达23.6%。     

Corrosion resistance of the electro-galvanized steel treated in a titanium conversion solution

The conversion coating can be obtained by using a solution containing titanium tetrachloride, fluorosilicate acid and nitric acid. The results of X-ray photoelectron spectroscopy (XPS) showed that the titanium conversion coating consisted of ZnO, TiO₂ and Zn₄Si₂O₇(OH)₂. The formation process of the titanium conversion coating was studied. Effects of the immersion time, pH value and solution temperature on the corrosion resistance and the chemical composition of the titanium conversion coating were investigated by the salt spray test (SST) and XPS, respectively. The results of XPS and SST showed that the titanium conversion coating displayed better corrosion resistance with higher contents of Si and Ti. Results of corrosion tests (the salt spray and electrochemical test) indicate that the corrosion resistance of the conversion coating by titanium solution is better than that of the conversion coating using the traditional chromate solution.     

Effect of the nitrogen inducing agents on the corrosion behavior of AlON-Al2O3 coatings prepared by electrolytic plasma processing on an Al6061 alloy

The electrolytic plasma processing method was used to prepare AlON-Al₂O₃ oxide coatings on an Al6061 alloy at room temperature in 15 min at a hybrid voltage with various nitrogen inducing agents. The nitrogen inducing effects were studied by X-ray diffractometer and scanning electron microscopy. The corrosion behavior of the coating was evaluated by electrochemical tests in a 3.5 wt% NaCl solution under static conditions by open circuit potential and potentiodynamic polarization. The results show that NaNO₂ is a suitable steady nitrogen inducing agent for preparing a uniform and dense AlON-Al₂O₃ coating on the Al6061 alloy to protect the substrate.