低介电常数多孔二氧化硅薄膜的制备与研究

本文报道了一种新型纳米多孔低介电常数薄膜的制备方法.以十六烷基三甲基溴化铵(CTAB)为模板剂,正硅酸乙酯为硅源,盐酸为催化剂,采用溶胶-凝胶技术,通过提拉法制备了二氧化硅透明介孔薄膜.用红外光谱、小角XRD、原子力显微镜对样品进行了表征,并采用椭偏仪和阻抗分析仪测量薄膜的折射率和介电常数.通过调节表面活性剂浓度和老化时间等实验条件制备出了K＜2.5、机械强度好的低介电常数薄膜.     

疏水型介孔氧化硅薄膜的制备与研究

报道了一种新型疏水型介孔氧化硅薄膜的制备方法.用红外光谱、小角XRD、原子力显微镜对样品进行了表征,并采用椭偏仪和阻抗分析仪测量薄膜的折射率和介电常数.该薄膜具有很低的介电常数和较好的机械强度,是一种可用于微电子工业、极富应用前景的低介电常数材料.     

低介电常数介孔氧化硅薄膜的结构与介电性能研究

利用溶胶-凝胶技术制备了介孔氧化硅薄膜.采用MIM结构,通过平行板电容器法测量了介孔氧化硅薄膜的介电常数,结果表明采用表面修饰的方法可以在保持较低介电常数(k=2.25)的前提下极大地降低薄膜的漏电流,提高薄膜的环境稳定性能.通过对富氏红外光谱的分析,讨论了薄膜的键结构与介电性能之间的关系,结果表明去除介孔氧化硅薄膜中的OH基团是提高薄膜介电性能的关键.     

低介电常数含氟氧化硅薄膜的研究

综述了近十年来低介电常数含氟氧化硅薄膜的研究状况,详细介绍了该薄膜在化学键结构、热性质、湿稳定性以及介电常数四个方面的特性,同时也简单介绍了薄膜的台阶覆盖度、填隙能力和漏电流特性,指出经硅薄膜是一种可有于集成电路中的极富应用前景的低介电常数材料。     

利用表面活性剂量改变孔洞率制备的纳米多孔SiO2膜

采用表面活性剂十六烷基三甲基溴化氨(CTAB)为模板剂,在酸性条件下产生多孔结构,再经热处理去除CTAB。实验中使用溶胶?凝胶技术,正硅酸乙酯(TEOS)为硅源,以及二次去离子水,盐酸为催化剂等原料,利用表面活性剂与硅源水解后形成的聚集体相互作用,在溶液中形成分子自组装体,制备前驱体溶胶。通过简单提拉迅速蒸发溶剂制备纳米多孔或纳米介孔SiO2薄膜,分析和研究了表面活性剂浓度对纳米多孔SiO2薄膜的结构和孔洞率的影响,通过操纵表面活性剂的含量,能控制薄膜的纳米结构、孔洞率、孔大小和孔的形态以及膜的形貌。小角度射线衍射、场发射透射电子显微镜、原子力显微镜显示可以制得具有六方、立方和由三维六方和简单立方组成的新相结构以及比介孔大的纳米多孔结构的薄膜。椭偏仪测量得到所制备薄膜的孔洞率为51.8%-65.6%,借助此孔洞率能计算薄膜的折射率和介电常数。     

具有特殊形貌ZSM5分子筛的控制合成

采用水热合成的方法,以硅溶胶为硅源,分别以四丙基溴化铵(TPABr)和四丙基氢氧化铵(TPAOH)为模板剂,得到了不同尺寸和形貌的ZSM-5分子筛,采用X射线衍射(XRD)和扫描电镜(SEM)对分子筛样品进行了表征。结果表明:以TPABr为模板剂时,通过改变水含量,可制备出较高结晶度具有成束的棒状、花瓣形的片状和微米尺度的球状ZSM-5分子筛;以TPAOH为模板剂时,随乙醇用量增加,合成的分子筛结晶度逐渐提高,晶粒尺寸和形貌变化大,当乙醇与SiO2物质的量比为1.9时得到结晶度高、形貌均一、尺寸1~2μm、六角板状的ZSM-5分子筛。     

介孔氧化硅薄膜材料的研究进展

介孔氧化硅薄膜在膜分离、传感器件、异相催化、低介电常数微电子绝缘片的应用方面具有潜在应用价值。首先简要介绍了介孔薄膜的制备途径，然后重点综述了介孔氧化硅薄膜的研究进展。     

二乙胺为模板剂合成SAPO-11型分子筛工艺研究

使用廉价的二乙胺为模板剂，选用合适的硅源，磷源，铝源，采用低温陈化过程，合成出了结晶度较好，高比表面积的SAPO-11分子筛。研究了硅源以及陈化温度等因素对SAPO-11分子筛合成的影响。结果表明静态品化所合成的SAPO—11分子筛的最佳硅源，在150℃下低温陈化2小时后再静态晶化所合成的SAPO-11分子筛具有较大的比表面积。     

反扩散法制备介孔MCM-48分子筛膜

采用反扩散法制备介孔MCM-48分子筛膜.首先以CTAB和P123为双模板,以TEOS为硅源,合成了MCM-48晶种.采用热浸渍法在α—Al2O3载体上预涂MCM-48晶种层.MCM-48分子筛膜的制备采用反扩散法,即通过硅源(TEOS)和模板剂(CTAB)溶液分别配制,载体管内外分开装填的工艺制备介孔MCM-48膜.利用XRD、SEM及单组分气体渗透实验对制备的样品进行表征.XRD结果表明,所合成的MCM-48晶种具有良好的长程有序性及较高的规整度.从SEM照片看,合成的MCM-48粉体具有晶形,颗粒大小均匀.能够在大孔径的α—Al2O3管状载体上形成平整、致密的晶种层.MCM-48分子筛膜的SEM照片表明,膜层很薄,并且是连续致密的.室温下,制备的MCM-48分子筛膜的H2渗透率达到10-7mol/(m2·s·Pa),压降为0.1 MPa时MCM-48膜对H2/N2的分离系数达到3.0.     

DMCPS电子回旋共振等离子体沉积的SiCOH低介电常数薄膜结构及物性研究

本文采用电子回旋共振(ECR)等离子体技术和十甲基环五硅氧烷(DMCPS)源开展了SiCOH薄膜的研究工作,获得了介电常数为2.88的SiCOH低介电常数薄膜.薄膜经400℃热处理后,膜厚减小,最大相对变化率小于15%,呈现较好的热稳定性.薄膜在1MV/cm场强下的漏电流为8.9×10-6A/cm2,且场强达到2.5 MV/cm时,未发生击穿现象,具有较优越的绝缘性能.因此,采用ECR-CVD技术和DMCPS源可以制备热稳定性优良的、绝缘性能优越的低介电常数SiCOH薄膜.     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Assessment of intakes of mixtures of radionuclides

Australia has several uranium mines and a large number of mineral sand mines, with associated processing facilities. Exposures resulting from these mining and processing operations usually involve intakes of mixtures of radionuclides. This work describes the development of a suite of first order, linear compartment models, based on the ICRP Publication 66 respiratory tract model, and an analytical solution to the decay equations, for assessing the consequences of such intakes. The computer programs based on these models directly compute excretion, organ retention and organ and whole-body doses for intakes of either single radionuclides or any mixture of radionuclides belonging to the same radioactive decay chain. The intake can be via inhalation, ingestion or injection, and can be acute, chronic or of limited duration. The starting concentration and degree of secular (dis)equilibrium can be specified for each radionuclide. No assumptions need to be made about the relative magnitudes of the radioactive half-lives of the different nuclides.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

卧式金属罐容量的测量结果不确定度

本文根据多年的实践检定经验 ,参照JJF1 0 59- 1 999《测量不确定度评定与表示》以及《测量不确定度表达 1 0讲》 ,对卧式金属罐容量的测量结果不确定度进行了评定。     

盐酸浓度不确定度的评估

通过对盐酸浓度标定的过程分析，找出影响结果的各个分量，进行不确定度的评定，按照计量技术规范给出标准的表示法。     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。