ZnO/CdO复合薄膜的制备及其性能研究

通过脉冲激光沉积法首次制备了ZnO/CdO复合薄膜。采用X射线衍射、光致发光和电阻率测量分析了薄膜的结构、光学和电学性能。光致发光谱表明所有ZnO/CdO复合薄膜都具有相同的PL发光峰,保持了未掺杂ZnO的发光特性。同时,复合薄膜的电阻率大大地下降了几个数量级,接近了纯CdO薄膜的电阻率。这可以用Matthiessen公式来解释。与传统掺杂方法相比,制备的ZnO/CdO复合薄膜可同时具有ZnO的发光特性和CdO的电学特性,从而获得单一TCO材料所不具备的性能,满足某些特殊需求。     

Sn掺杂CdO透明导电薄膜的制备和光电性能研究

通过脉冲激光法在石英玻璃基底上沉积了锡掺杂氧化镉(Sn-CdO)透明导电薄膜.X射线衍射,分光光度计和霍尔效应仪检测了薄膜的结构、光学和电学性能.结果表明Sn的掺杂提高了薄膜[111]方向的择优生长,而且促使了(200)晶面衍射角增大.Sn-CdO薄膜的光学禁带宽度随着Sn掺杂含量的增加而变宽.另外,适量的Sn掺杂可以明显改善CdO薄膜的电学性能,比如2.9 at％ Sn掺杂CdO薄膜的电阻率是未掺杂薄膜的十二分之一,载流子浓度是未掺杂的十三倍.因而光学和电学性能的改良使得Sn-CdO薄膜作为透明导电材料具有重要的应用价值.     

衬底温度对In掺杂CdO薄膜的结构和性能的影响

Transparent indium-doped cadmium oxide（In-CdO） thin films were deposited on quartz glass substrates by pulsed laser deposition（PLD） from an ablating Cd-In metallic target.The effect of substrate temperature on the structural,optical and electrical properties of In-doped CdO thin films were studied in detail.The optical transmittance of In doped CdO films are obviously influenced by the substrate temperature.All films exhibit a transmittance higher than 75%in the visible region.More significantly,In-doping leads to an evident widening of optical band gap from 2.56 to 2.91 eV;and the increase in optical band gap is found to depend on the deposition temperature.It is also seen that the electrical properties of these films strongly depend on the substrate temperature. The In-CdO thin film grown at 300℃has low resistivity(1.15×10^-4Ω·cm),high carrier concentration(5.35×10²⁰ cm^-3),and high mobility（101.43 cm²/（V·s））.     

铝材表面激光熔覆Ni_(1.5)Co_(1.5)FeCrTi_x高熵合金层的组织与性能

为了提高铝合金的耐磨性及耐蚀性并降低高熵合金中元素偏析的现象,采用CO_2激光熔覆技术在铝基体表面制备了Ni_(1.5)Co_(1.5)FeCrTi_x高熵合金熔覆层。借助光学显微镜、扫描电镜、X射线衍射仪和电化学工作站检测技术研究了Ti含量对Ni_(1.5)Co_(1.5)FeCrTi_x熔覆层显微组织和耐蚀性能的影响。结果表明:Ni_(1.5)Co_(1.5)FeCrTi_x高熵合金熔覆层主要相结构为简单的面心立方相、金属间化合物相和Laves相;当Ti含量摩尔比从0.5增至2.0时,Ni_(1.5)Co_(1.5)FeCrTi_x高熵合金熔覆层的表面硬度从510 HV增加到554 HV,在0.5 mol/L HNO_3溶液中具有优异的耐蚀性能。     

高强度马氏体35CrMo钢的绝热剪切特性

通过分离式霍普金森压杆装置研究了3种不同强度(X700、X1000、X1600)高强钢在应变速率为1500~8000 s~(-1)范围内的绝热剪切特征。结果表明:X700钢在应变速率≤8000 s~(-1)时无绝热剪切行为;X1000钢在应变速率8000 s~(-1)、X1600钢在应变速率6000 s~(-1)、8000 s~(-1)时出现绝热剪切行为,且X1600钢的绝热剪切带数量较多。绝热剪切带的硬度高于基体硬度且与基体有一定的关系,X1600钢绝热剪切带硬度比X1000钢增加18%以上,且X1600钢发生明显的破裂。随着强度的增加,高强度马氏体钢在高应变速率下微裂纹扩展倾向大,剪切带端部开裂严重。     

电子束冷床熔铸大规格TA1纯钛扁锭的多道次降温热变形行为研究

针对电子束冷床(EB)熔铸的8 000 mm×1 570 mm×200 mm规格TA1纯钛扁锭，沿轧制方向取样后利用Gleeble-3500热模拟试验机在不同变形参数下进行总变形量75%的多道次降温热压缩实验，研究了不同部位铸态扁锭的多道次压缩热变形行为、微观组织及其细化机理.结果表明：随着道次变形温度从890℃降低到850℃,变形量从13%提高到17%,流变应力呈阶梯升高而道次间软化率逐渐降低；多道次热压缩后，铸态粗大的等轴晶和柱状晶由于发生动态回复与再结晶及静态软化现象，破碎细化成较为细小均匀的等轴α相，平均晶粒尺寸由3.5 cm降至21μm,铸锭不同部位微观组织显示出相似的变化规律；综合分析，EB炉熔铸的TA1纯钛扁锭在相变点以上开始塑性变形并在α相区完成大部分变形，能够提高动态再结晶过程中的形核率，有利于细化热轧组织.     

电子束冷床熔铸TC4合金的多道次热变形行为

利用Gleeble-3500热模拟试验机,对电子束冷床熔铸制备的Ti-6Al-4V(TC4)钛合金在变形温度为850～1000℃、应变速率为0.01～1 s~(-1)和总变形量为50%条件下进行多道次热压缩模拟实验,研究铸态合金的多道次压缩热变形行为及微观组织演变规律。结果表明:合金的流变应力随变形温度的升高和应变速率的降低均呈降低趋势;不同变形温度下随应变速率的降低,合金的软化率逐渐升高,且变形温度越高,各道次间软化率趋于稳定;在变形温度950～1000℃、应变速率0.01～0.1 s~(-1)范围内合金的组织均得到不同程度的细化和均匀化,并发生动态回复与再结晶现象,此变形参数下合金的热加工性能稳定,可为电子束冷床熔铸TC4合金的铸态直接多道次热轧成形提供指导。     

Cubic AlN thin film formation on quartz substrate by pulse laser deposition

Cubic AlN thin films were obtained on quartz substrate by pulse laser deposition in a nitrogen reactive atmosphere. A Nd-YAG laser with a wavelength of 1064 nm was used as the laser source. In order to study the influence of the process parameters on the deposited AlN film, the experiments were performed at various technique parameters of laser energy density from 70 to 260 J/cm², substrate temperature from room temperature to 800℃ and nitrogen pressure from 0.1 to 50 Pa. X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy were applied to characterize the structure and surface morphology of the deposited AlN films. It was found that the structure of AlN films deposited in a vacuum is rocksalt under the condition of substrate temperature 600-800℃, nitrogen pressure 10-0.1 Pa and a moderate laser energy density (190 J/cm²). The high quality AlN film exhibited good optical property.     

Cd掺杂ZnO薄膜的光致发光性能研究

三元半导体Cd掺杂ZnO薄膜通过脉冲激光法沉积 在石英玻璃基底上,Gd含量x从0增加到0.23。X射线衍射(XRD)图谱表明,所有Zn1－xCd xO薄膜都具有c轴取向的六方纤锌矿结构,而且c轴 晶格常数随着 x的增加而增加。原子力显微镜(AFM)观察到,随着x的增加,Zn1－xCdxO 薄膜的晶粒尺寸逐渐减小。光致发光(PL)和透过率 测量都证实,随着x的增加,薄膜的禁带宽度Eg从3.27eV降低到了2.78eV,同时导致了PL峰半高 宽(FWHM)的变大。PL峰迁移到了可见光范围内,使得Zn1－xCdxO薄膜可以应用在可见光发光二极管及其它高效率的光电 子器件。