TiN/AlN纳米多层膜的制备及耐蚀性能

采用多弧离子镀技术制备了TiN/AlN纳米多层膜,并通过多层膜在酸中的浸泡试验及极化曲线测定,对比研究了TiN/AlN纳米多层膜和TiN薄膜的耐蚀性能.结果表明,由于TiN/AlN纳米多层膜中铝的钝化作用及薄膜的特殊层结构,TiN/AlN纳米多层膜比TiN薄膜具有更优良的耐腐蚀性能.     

TiN/AlN纳米多层膜的调制周期及力学性能研究

采用一种新型的离子束辅助非平衡反应磁控溅射设备制备了TiN/AlN纳米多层复合膜.采用XRD衍射、TEM、显微硬度计和干涉显微镜对TiN/AlN纳米多层膜的微结构和力学性能进行了表征.结果表明TiN/AlN多层膜有良好的周期;调制结构影响薄膜的择优取向,薄膜整体表现出硬度增强的效果,硬度随调制周期的变化而变化并在调制周期为7.5 nm时达到最大值.     

纳米超硬多层膜研究现状及发展趋势

分别从溅射法和蒸发法两个方面评述了近年来纳米多层膜制备工艺的最新进展,在此基础上介绍了脉冲激光沉积(PLD)工艺制备纳米超硬多层膜的新方法.对典型的超硬膜TiN、(Ti,Zr)N、(Ti,Al)N、TiN/SiO2、B1-SiC、TiN/SiN4进行了简单回顾,并对其硬度、残余应力、摩擦磨损和抗氧化性能等方面做了详细的比较.最后,简述了纳米超硬多层膜表征的一般手段,并展望了发展前景.     

电弧离子镀TiN/Ti纳米多层膜的力学性能

采用多弧离子镀技术,在不同沉积参数下合成具有纳米调制周期的TiN/Ti多层膜。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、XP-2台阶仪、XP型纳米压痕仪、X射线能谱仪(EDS)研究了调制周期对TiN/Ti纳米多层膜微观结构、表面形貌以及力学性能的影响。结果表明,膜层由TiN和Ti交替组成,不存在其它杂相,且TiN薄膜以面心立方结构沿(111)密排面择优生长;TiN/Ti多层膜外观致密、平滑、颜色均匀金黄,随着调制周期的减小,薄膜表面大颗粒数量和尺寸均减小,且氮含量逐渐升高,膜层硬度呈现出增大的趋势。     

TiN／AIN纳米多层膜的调制周期及力学性能研究

采用一种新型的离子束辅助非平衡反应磁控溅射设备制备了TiN／AlN纳米多层复合膜。采用XRD衍射、TEM、显微硬度计和干涉显微镜对TiN／AlN纳米多层膜的微结构和力学性能进行了表征。结果表明：TiN／AlN多层膜有良好的周期；调制结构影响薄膜的择优取向，薄膜整体表现出硬度增强的效果，硬度随调制周期的变化而变化并在调制周期为7、5nm时达到最大值。     

真空阴极离子镀法制备Ti/TiN/Zr/ZrN多层膜

过去,在不锈钢上沉积10μm以上多元多层软硬交替Ti/TiN/Zr/ZrN厚膜用以提高材料耐腐蚀性能的报道不多.采用阴极电弧离子镀结合脉冲偏压的方法制备了厚度选15 μm的Ti/TiN/Zr/ZrN多层膜.运用扫描电镜(SEM)、X射线衍射(XRD)、显微硬度计、划痕仪等考察了多层膜的形貌、厚度、相组成、硬度以及膜/基结合力,并利用电化学方法评价了基体、单层TiN薄膜以及多层膜的电化学腐蚀性能.结果表明:制备的Ti/TiN/Zr/ZrN多层膜界面明晰、结构致密、晶粒细小;膜/基结合力大于70 N,显微硬度达28 GPa;多层膜比单层TiN膜在提高1Cr11Ni2W2MOV基体的抗腐蚀能力方面具有更显著的作用.     

AlN/TiSiN纳米多层膜的微观组织和力学性能研究

采用TiSi复合靶和Al靶,用射频磁控溅射工艺沉积不同TiSiN层厚度的AlN/TiSiN纳米多层膜。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)和纳米压痕仪研究了不同TiSiN层厚度对AlN/TiSiN纳米多层膜的微观组织和力学性能的影响。结果表明,随着TiSiN层厚度的增加,AlN相的结晶程度先增加后降低,涂层的硬度先提高后降低,当TiSiN层厚度为0.5nm时具有最高的硬度和弹性模量。HRTEM观测可知,在TiSiN层厚度为0.5nm时,TiSiN层在AlN层的模板作用下呈密排六方结构,并与AlN层呈共格外延生长,薄膜的强化主要与共格外延生长结构有关。     

结构调制超硬Ti/TiN纳米多层膜的制备及其尺寸效应

使用多弧离子镀技术在高速钢基体上制备了调制周期为5~40 nm的Ti/TiN纳米多层膜,用扫描电子显微镜(SEM)、X射线能谱仪(EDS)、X射线衍射仪(XRD)、纳米压痕仪和划痕仪等手段表征薄膜的微观结构和性能,研究了调制周期对Ti/TiN纳米多层膜性能的影响,并讨论了在小调制周期条件下Ti/TiN纳米多层膜的超硬效应和多弧离子镀技术对纳米多层膜硬度的强化作用。结果表明,与单层TiN相比,本文制备的Ti/TiN纳米多层膜分层情况良好,薄膜均匀致密,没有明显的柱状晶结构,TiN以面心立方结构沿(111)方向择优生长。随着调制周期的减小薄膜的硬度呈现先增大后减小的趋势,并在调制周期为7.5 nm时具有最大的硬度42.9 GPa和H/E值。这表明,Ti/TiN在具有最大硬度的同时仍然具有良好的耐磨性和韧性。Ti/TiN纳米多层膜的附着力均比单层TiN薄膜的附着力高,调制周期为7.5 nm时多层膜的附着力为(58±0.9) N。     

铝基复合材料表面多层复合厚膜的研究

对含50%AlN颗粒的铝基复合材料进行预处理后,在其表面依次采用浸锌化学镀镍工艺制备Ni-P过渡层,采用脉冲偏压磁过滤多弧离子镀工艺沉积硬质Ti/TiN调制周期膜,采用脉冲等离子体化学气相沉积工艺制备含氢类金刚石(DLC)膜等工艺最后形成了多层复合薄膜体系。利用X射线衍射仪、扫描电子显微镜、光谱仪、原子力显微镜、微载荷显微硬度仪、摩擦磨损试验机等设备分析了复合薄膜的组织结构、膜层形貌、截面形貌、显微硬度和摩擦系数等性能特点。测试表明:铝基复合材料/Ni-P层/Ti/TiN调制周期膜/含氢DLC膜这一梯度膜系具有结构交替变化,相邻界面形成混合层,性能梯度分布,硬度逐渐增加,摩擦系数小的特点。该复合工艺能够有效地解决铝基复合材料上制备硬质厚膜的热适配和晶格错配度大的难题,制备薄膜具有良好的膜基结合性能。     

TiN/Si3N4纳米多层膜的生长结构与超硬效应

采用磁控溅射方法制备了一系列不同Si3N4和TiN层厚的TiN/Si3N4纳米多层膜,采用X射线衍射、高分辨电子显微分析和微力学探针表征了薄膜的微结构和力学性能,研究了Si3N4和TiN层厚对多层膜生长结构和力学性能的影响.结果表明:当Si3N4层厚小于0.7 nm时,原为非晶的Si3N4在TiN的模板作用下晶化并与之形成共格外延生长的柱状晶,使TiN/Si3N4多层膜产生硬度和弹性模量异常升高的超硬效应.最高硬度和弹性模量分别为34.0 GPa和353.5 GPa.当其厚度大于1.3 nm时,Si3N4呈现非晶态,阻断了TiN的外延生长,多层膜的力学性能明显降低.此外,TiN层厚的增加也会对TiN/Si3N4多层膜的生长结构和力学性能造成影响,随着TiN层厚的增加,多层膜的硬度和弹性模量缓慢下降.     

广义距离回归

实际工作中涉及的两个测得量的回归极为有用.从一个量有不确定度的一般回归讨论到两个量有不确定度的正交回归,最后讨论到普遍的广义距离回归,并以实例说明.     

Regression and unbiased regression

Summary A method of evaluation of the efficiency of a regression function is given. Unbiased regression is defined. In annex, a method of computation of mean values is given, which is very useful in many cases.     

The robustness and efficiency of trimmed elemental estimation in regression analysis: a Monte Carlo simulation study

Mayo and Gray [Am Statist 51 (1997) 122] introduced the leverage-residual weighted elemental (LRWE) classification of regression estimators and proposed a new method of estimation called trimmed elemental estimation (TEE). In this article, we perform a simulation study of the efficiency of certain TEE estimators relative to ordinary least squares under normal errors and their robustness under various non-normal error distributions in the context of the simple linear regression model. Comparisons among these estimators are made on the basis of mean square error and percentiles of the absolute estimation errors in the simulations.     

自变量含有类型变量的线性回归模型的树方法

给出了求解自变量含有类型变量的线性回归模型的树方法。它是一个非参数方法。讨论了修剪树对参数估计和预测的影响，给出了通过修剪树提高参数估计和预测精度的充要条件。     

Statistical Programs for High Speed Computers

It is pointed out that the inferential theory of the segmented regression model depends strongly on whether or not continuity at the change-point is assumed. In particular, if it is not, the likelihood ratio test for the presence of two segments tends to infinity.     

Regression approach to tire reliability analysis

The paper considers an empirical approach to the root-cause analysis of a certain kind of automobile tire failure. Tire life data are obtained from a laboratory test, which is developed to duplicate field failures. A number of parameters related to tire geometry and physical properties are selected as explanatory variables that potentially affect a tire's life on test. Analysis of the life test data is performed via the Cox survival regression model. The paper also elaborates on the application of an ordinary (non-survival) linear regression to modeling the failure initiation and propagation. The developed statistical models help to identify the elements of tire design affecting the probability of tire failure due to the failure mode in question.     

Alternative Modeling Strategies for Characterizing Radio Performance

Historically, the application of logistic and Poisson regression has been focused in the social science and medical fields where the response variable typically has only a few possible outcomes. These techniques are not commonly applied to characterize military operations even though response variables that measure success or failure are commonly encountered in this field. This paper explores the application of ordinal logistic and Poisson regression as alternatives to ordinary least squares estimation for modeling operational performance in a military testing environment. The operational test planners chose a nested face‐centered experimental design, which was executed to collect test data. Three modeling techniques were employed in the analysis: multiple linear regression, ordinal logistic regression, and Poisson regression. The purpose of the study was to determine which regression technique best fits the test data. Cross validation and model goodness comparison were accomplished by assessing that the model fits for each model type in combination with a comparison of significant main effects and interactions. Finally, contrasts are provided relative to the ease of implementing each technique. Copyright © 2016 John Wiley & Sons, Ltd.     

Partitioned Ridge Regression

In this paper we examine the relationship between the general ridge estimator and the standardized ridge estimator.     

Asymptotic efficiency properties of least squares in an ultrastructural model

This paper considers the estimation of both the intercept term and the slope parameter in a linear ultrastructural model using direct regression and reverse regression methods. Without assuming the errors to be normally distributed, asymptotic expressions for the bias and the variance of the estimators are derived and analyzed. The effect of departure of the errors from normality is also studied.     

An Exact Confidence Set for a Maximum Point of a Univariate Polynomial Function in a Given Interval

Construction of a confidence set for a maximum point of a function is an important statistical problem which has many applications. In this article, an exact 1 ? α confidence set is provided for a maximum point of a univariate polynomial function in a given interval. It is shown how the construction method can readily be applied to many parametric and semiparametric regression models involving a univariate polynomial function. Examples are given to illustrate this confidence set and to demonstrate that it can be substantially narrower and so better than the only other confidence set available in the statistical literature that guarantees 1 ? α confidence level.