部分线性模型参数估计的Bahadur渐近有效性

文中讨论了部分线性模型 Ｙｉ ＝ Ｘ Ｔｉ Ｕ＋ ｇ （ Ｔｉ） ＋ Ｘｉ,ｉ＝ １,２,…,ｎ 中参数 Ｕ估计的性质,这里ｇ 是未知的 Ｈ氹ｌｄｅｒ 连续函数, Ｘｉ 是随机误差,（ Ｘｉ, Ｔｉ）,ｉ＝ １,２,…,ｎ 是已知的设计点。在某些条件下,证明了 Ｕ的最小二乘估计和最大似然估计是 Ｂａｈａｄｕｒ 渐近有效估计。     

博士信箱

问： 欲绕一分频器．如何确定线圈尺寸和匝数？如用φ １．２ｍｍ漆包线绕Ｌ１＝１．２２ｍＨ、 Ｌ２＝０．１２ｍＨ的线圈？如何设计。能否给出计算公式？用什么方法测线圈电感？（椒江市 陈志泉） 答： 可使用下面的速查表。表中,Φ是漆包线线径,Ｄ是绕制骨架的直径,Ｈ是骨架的高度（尺寸单位：ｍｍ,电感值单位ｍＨ）。 但实际需求的电感值往往不能直接查到,这时候可以采用一逼近公式： 设所求电感Ｘ值为 １． ２２ｍＨ,采用 Φ＝１．２, Ｄ＝２５,Ｈ＝２６的方法,则Ｘｉ＝１．２,Ｘｉ＋１＝１．４,Ｙｉ－２１６,Ｙｉ十１＝２…     

Ti／Al多层金属薄膜AES深度剖析的目标因子分析

目标因子分析法（ＴＦＡ）是一种对多元系统进行统计分析的计算数学方法。结合这种方法对Ｔｉ／Ａｌ多层金属薄膜的俄歇电子谱（ＡＥＳ）深度剖析结果进行了仔细的分析，获得了Ｔｉ、Ａｌ、Ｏ、Ｓｉ各元素的化合状态的深度分布情况，并与Ｘ射线光电子谱（ＸＰＳ）分析结果相一致．     

Al／SiC复合材料界面反应的DTA研究

本文以多层膜模拟复合材料界面反应，用ＤＴＡ及ＸＲＤ研究了ＴｉＣ，Ａｌ２Ｏ３和ＳｉＯ２作为Ａｌ／ＳｉＣ体系的反应阻挡层的作用．发现经７００℃，１ｈ处理后，Ａｌ２Ｏ３不与Ａｌ或ＳｉＣ反应，有很好的阻挡作用；ＴｉＣ与Ａｌ反应生成ＴｉＡｌ３后也能阻止Ａｌ与ＳｉＣ的反应；ＳｉＯ２与Ａｌ反应，导致一定数量的Ｓｉ溶入Ａｌ中，是否起阻挡作用有待进一步分析．     

Si3N4陶瓷材料高温氧化层的分析

利用ＸＲＤ，ＥＰＭＡ，ＸＰＳ和ＳＥＭ的分析方法，研究了在１３００℃下氧化后Ｓｉ３Ｎ４陶瓷材料表面氧化层的组成的形貌，结果表明，Ｓｉ３Ｎ４陶瓷材料的表面氧化层是由方石英相和含有Ａｌ２Ｏ３，ＣａＯ等杂质的ＳｉＯ２质玻璃相所组成，其中ＳｉＯ２玻璃相听Ａｌ２Ｏ３，ＣａＯ等杂质的含量随氧化时间的增加而逐渐增加，同时在氧化层的内部都还存在部分Ｓｉ２Ｎ２Ｏ相。     

镀锡层抗高温性能与工艺研究

针对铜基引线框架镀锡层高温易缩锡变色及常温不耐盐水腐蚀等问题，采用了不同电镀工艺，分析了镀层显微形貌、物相结构、抗电化学腐蚀性能与力学性能。结果表明：镀锡前，对铜表面进行充分去氧化及粗化，可极大提高镀锡层结合力，有效防止高温缩锡现象；镀锡后，镀层浸泡抗高温氧化剂，可有效防止高温发黄以及提高耐盐水腐蚀性能。     

补镀锡层的方法

补镀锡层的方法合肥市东风机械总厂（２３００２２）周弘工件镀锡后，如果锡层出现厚度不够、孔隙试验不合格或者表面有轻微斑点等疵病，可通过在锡层上补镀锡来达到修复的目的。现介绍如下。如果工件镀锡层表面已站污，但状况不严重或者工件镀锡后已放置了一段时间，其补...     

TiO_2在MCM-41内表面单层及双层分散的结构表征

首次以有机物钛酸丁酯为前驱体,合成了ＴｉＯ２呈单层分散状态（Ｔｉ／Ｓｉ＝０.２０）或双层分散状态（Ｔｉ／Ｓｉ＝０．３９）的介孔分子筛ＭＣＭ－４１（Ｓｉ／Ａｌ＝３５）,并以 ＸＲＤ,ＦＴＩＲ,Ｎ２吸附－脱附,固体ＵＶ－ｖｉｓ 漫反射等表征手段对其结构特征和氧化钛分散状态进行了研究．结果表明： ＴｉＯ２在介孔分子筛ＭＣＭ－４１孔道中分散, ＭＣＭ－４１骨架结构结晶度降低,但是附着二层ＴｉＯ２后,仍能保持长程有序结构; ＴｉＯ２与ＭＣＭ－４１孔道表面的ＳｉＯ２以化学键连接,生成Ｓｉ－Ｏ—Ｔｉ键;无论是单层还是双层分散的 ＴｉＯ２在 ＭＣＭ－４１内孔壁均匀分散;且由于ＴｉＯ２粒子的减小使其对紫外光的吸收发生明显的蓝移现象．     

SiC含量和电流密度对Ni—SiC镀层耐磨性的影响

研究了镀液中ＳｉＣ含量对镀层中ＳｉＣ含量的影响以及镀层中ＳｉＣ含量和电流密度对镀层硬度和耐磨性的影响。试验结果表明，随度层中ＳｉＣ含量的增加，镀层硬度增加；随镀层中ＳｉＣ含量和电流密度增加，耐磨性增大到极大值后又下降。     

硅基GaN外延层的SIMS及XPS研究

采用真空反应法在硅基上制备出ＧａＮ外延层。利用二次离子质谱和Ｘ射线光电子能谱对ＧａＮ外延层进行了深度剖析和表面分析,结果表明,外延层中Ｇａ和Ｎ分布均匀;在表面处Ｇａ发生了偏聚,外延层中还存在Ｓｉ,Ｏ等杂质,但这些并未影响到ＧａＮ外延层的物相及发生性能,实验还表明,在外延生长前采用原位清洗可去除Ｓｉ衬底表面的氧。     

Determination of optimum welding parameters in connecting high alloyed X53CrMnNiN219 and X45CrSi93 steels by friction welding

In this study, different welding parameters were applied to two different steels with high alloys and mechanical and metallographical investigations are performed. Thus, the optimum welding parameters were determined for these materials and working conditions. 12·30 diameter steel bars made up of 1·4871 (X53CrMnNiN219) and 1·4718 (X45CrSi93) steel were used as experimental material. The material loss increased with increase in friction and rotating pressure. No fracture at the welding region was observed and the highest fracture energy was identified in B5 group. Based on micro hardness investigation; the hardness profile reached its minimum value at the welding region.     

利用X射线法测定淬回火GCr15钢的硬度

研究了淬回火GCr15钢洛氏硬度与马氏体(211)晶面X射线半高宽间的关系，用数理统计方法对实验数据进行了分析。结果表明，洛氏硬度与半高宽间存在良好的相关性，相关系数约为0．973；建立了洛氏硬度与半高宽间的线性均方回归方程，利用该方程可预测淬回火GCr15钢的硬度。     

X70管线钢洛氏硬度试验结果的不确定度评定

依据GB／T230．1—2009规定的试验方法,利用Wilson 2001T洛氏硬度计对某钢厂X70管线钢进行了洛氏硬度（HRB）试验,从试验重复性、硬度计复现性等多方面对洛氏硬度试验的不确定度来源进行了分析和阐述,对每个不确定度分量进行了逐一评定,最终给出了扩展不确定度及测量结果的不确定度报告。结果表明：该X70管线钢洛氏硬度测量平均值为（78．5±2．4）HRB,包含因子k=2。该方法对金属材料洛氏硬度的测量不确定度评定具有一定的参考价值。     

Effects of carbide-forming elements on the response to thermal treatment of the X45Cr13 martensitic stainless steel

The effects of carbide-forming elements on the response to thermal treatment of the X45Cr13 martensitic stainless steel have been investigated. Heat treatments consisted of austenitizing for 60 s at temperatures ranging from 1000–1250 °C. The higher is the solution treatment temperature, the less M23C6 carbide is left out of solution in the austenite. As a result, the concentration of carbon and alloying elements in the martensite increases and, therefore, an increase in the hardness until a maximum value of 710 HV was found at austenitizing temperatures of 1120 and 1130 °C for the steels X45Cr13 and X45CrMoV14, respectively. At higher austenitizing temperatures, the presence of retained austenite was observed, which leads to a lowering of the hardness value. The higher amount of carbide-forming elements in the X45CrMoV14 determines an increase in retained austenite from 3 vol% to about 30 vol%. Thus, a drop in the hardness value from 710 to 680 and 585 for the steels X45Cr13 and X45CrMoV14, respectively, was found. © 1998 Kluwer Academic Publishers     

Aging Behaviors of W-Ni-Fe Ternary Alloys with High Ni-to-Fe Ratios

The hardness variation of two kinds of alloys with 36 wt pct W content and 7/3, 9/1 Ni-to-Fe ratios during strain aging at 800℃ was studied. The microstructures of the aged alloys were analyzed by X-ray diffraction and TEM. The results show that the strain aging hardness of W-Ni-Fe ternary alloy with 7/3 Ni-to-Fe ratio decreases monotonically with the increase of aging time. Under the same conditions, the hardness of 9/1 Ni-to-Fe ratio alloy decreases in the initial aging stage, but then increases as aging process goes on. X ray diffraction and TEM analysis show that there is not any precipitation depositing from the alloy with 7/3 Ni-to-Fe ratio during aging. The monotonic decrease in hardness of this alloy during aging process results from the recovery, recrystallization and solid solubility declining. In the alloy of 9/1 Ni-to-Fe ratio, the fine β phase precipitates dispersively during aging which hardens the alloy. The two different kinds of mechanisms (the softening one and the hardening one) decide the hardness variation of the alloy with 9/1 Ni-to-Fe ratio mentioned above.     

Development of extended zero-order release gliclazide tablets by central composite design

The purpose of this study was to develop an extended release tablet formulation containing gliclazide as a model drug by optimization technique. A central composite design was employed with pH-dependent matrix forming polymers like keltone-HVCR (X1) and eudragit-EPO (X2) as independent variables. Five dependent variables were considered: hardness, percent drug release after 1 hr, percent drug release after 6 hr, diffusion exponent and time required for 50% of drug release. Response surface methodology and multiple response optimization utilizing a quadratic polynomial equation were used to obtain an optimal formulation. The results indicate that Factor X1 along its interaction with Factor X2 was found to be significantly affecting the studied response variables. An optimized formulation, containing 8 mg of keltone-HVCR and 14.10mg of eudragit-EPO, provides a sufficient hardness (> 4.5 kg/cm2) and optimal release properties. The desirability function was used to optimize the response variables, each having a different target and the observed responses were highly agreed with experimental values. The release kinetics of gliclazide from optimized formulation followed zero-order release pattern. The dissolution profiles of optimized formulation before and after stability studies were evaluated by using similarity factor (f2) and were found to be similar. The results demonstrate the feasibility of the model in the development of extended release dosage form.     

Tribologische Modelluntersuchungen an metallischen Werkstoffen für Formeinsätze zum Mikro‐Pulverspritzgießen mit ZrO2‐Formmasse

Tribological studies on metallic materials used as mould inserts in micro powder injection moulding (microPIM) with zirconia feedstock Wear behaviour of steel X38CrMoV5‐1 and C 45E, electroplated nickel and brass Cu63Zn37 used as mould inserts in micro powder injection moulding (microPIM) was studied in two different laboratory tribometers. Using an abrasive wheel test with 220 mesh flint the volumetric wear increased with decreasing hardness from steel to nickel and brass. Experiments using a laboratory tester simulating powder injection moulding with zirconia feedstock at 170 and 190°C showed contrary results. Volumetric wear of the softer materials nickel and brass was significantly lower than that of steel X38CrMoV5‐1 and C 45E. The presented results indicate that in micro powder injection moulding wear behaviour can depend more on microstructural parameters like homogeneity or the ability of work‐hardening and deformation but on hardness of the materials.     

Effect of aluminum content on solidification microstructure and properties of Fe‐Cr‐B‐Al alloys

The microstructures and mechanical properties of eight kinds of Fe‐Cr‐B‐Al alloys containing X wt.%Al‐0.35 wt.%C‐10.0 wt.%Cr‐1.4 wt.%B‐0.6 wt.%Si‐0.8 wt.%Mn (X = 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0) were studied by means of optical microscopy (OM), scanning electron microscopy (SEM), X‐ray diffraction (XRD), Rockwell hardness and Vickers micro‐hardness testers. The results indicate that the as‐cast microstructure of aluminium‐free sample consists of the martensite, austenite and eutectic borocarbides, and the eutectic borocarbides are the mixture of (Fe, Cr)₂B and (Cr, Fe)₇(C, B)₃, and its hardness reaches 65 HRC. When a small amount of aluminium element (Al ? 1.0 wt.%) is added, the phase composition has no significant change, and the hardness excels 65 HRC. When the concentration of aluminium reaches 1.5 wt.%, the matrix of Fe‐Cr‐B‐Al alloy becomes pearlite and δ‐ferrite, leading to a sharply decrease of the hardness. The proportion of ferrite goes up along with increasing aluminium concentration, and the hardness of Fe‐Cr‐B‐Al alloy has slight decrease.     

On the prediction of tensile properties from hardness tests

The possibility of correlating the hardness to the tensile properties of a material has been investigated using Assab 760 steel, mild steel and API Std 5LX grade X60 pipeline steel that have been heat-treated for different times at various tempering temperatures and 6063-T1 aluminium that has been solution heat-treated. It is found that the strain hardening coefficient and the strength coefficient of all materials tested were linearly related to the hardness, irrespective of the type of hardness measurement used. Using these relationships, equations were defined to estimate the yield and ultimate tensile stresses of the materials. Good agreement between experimental results and estimated values was obtained for all materials studied. The feasibility of using the present findings in non-destructive field testing is discussed.     

Effect of quenching temperature on microstructure and performance of Al‐bearing cast boron steel

The effects of quenching temperature on microstructure and performance of Al‐bearing cast boron steel (ACBS) containing 0.25–0.45%C, 1.5–1.8%B and 1.4–1.6%Al were investigated by means of the optical microscopy (OM), the scanning electron microscopy (SEM), X‐ray diffraction (XRD), Rockwell hardness and Vickers micro‐hardness tester. The results show that the solidification structures of cast steel consist of high hardness boride, ferrite, pearlite and a small quantity of martensite when 1.5–1.8%B and 1.4–1.6%Al are added into the carbon steel. The metallic matrix of ACBS changes into single martensite from the mixed structure of ferrite, pearlite and martensite along with the increase of quenching temperature. The increase of quenching temperature also leads to the transformation of boride from continuous shape to isolated shape. Moreover, the micro‐hardness of matrix and macroscopical hardness increase with the increase of quenching temperature. When the quenching temperature excels 1000°C, the hardness has a slight decrease. ACBS has good comprehensive properties after heat treatment at 1000°C.