Use of Tablet Tensile Strength Adjusted for Surface Area and Mean Interparticulate Distance to Evaluate Dominating Bonding Mechanisms

In this study, tablet tensile strength has been adjusted for tablet surface area and the average distance between particles in compacts of different materials. The aim of the study was to evaluate the feasibility of using this concept to assess the dominating interparticulate bonding mechanisms. Adjustment of the tensile strength for both tablet surface area and mean pore radius gave similar bonding strength values for materials bonding mainly by weak distance forces (crystalline lactose, sucrose, and microcrystalline cellulose) almost independently of compaction pressure. However, particle size and other factors may still affect the compensated strength values. The bond strength was much higher and more varied for materials bonding also with solid bridges (potassium chloride, sodium chloride, and possibly also sodium bicarbonate and amorphous lactose). For these materials, particle size and compaction pressure had a substantial effect on the bond strength. It is probably the formation of continuous bridges between adjacent particles that is important in these materials rather than the surface properties and the average distance between particles positioned at some distance from each other. Hence, adjusting the tensile strength of compacts does not necessarily reflect all the dominating factors responsible for interparticulate bonding. Nonetheless, adjustment for tablet surface area and mean pore radius allowed discrimination between different dominating interparticulate bonding mechanisms in these compacted materials.     

冷压焊界面结合机理与结合强度研究现状EI北大核心CSCD

固相焊接因其突出的技术优势在先进金属结构材料焊接中获得越来越多的应用。冷压焊作为一种特殊固相焊接方法,其界面结合机理和结合强度预测是长期以来困扰研究者的两大难题。本文综述了冷压焊界面结合机理理论研究现状,重点讨论了冷压焊接头界面结合强度影响因素及其预测模型,并指出了今后冷压焊界面结合机理需综合考虑扩散、再结晶、位错等因素,同时结合强度预测模型应考虑变形程度、变形速率、变形温度等方面。     

金属结合剂对金刚石把持力的增强措施及增强机制评述

介绍三种提高金属结合剂对金刚石把持力的措施 ,综述了它们的研究和应用现状 ,并指出研究应用中存在的问题     

Effect of Binder and Geometry of Tablet on Rate of Wear, Hardness and Tensile Strength

The relation of concentration of starch and povidone in tablets of Emcompress and Fast-Flo lactose and the relation of pressure applied to the tablets to wear rate constant, hardness and tensile strength are reported. The extent to which these parameters are changed by concentration and applied pressure is compared. The influence of shape on the wearability of flat face, flat face bevel edge bisect and standard convex tablets with and without a lubricant was studied.     

Use of Acoustic Emission to Evaluate Residual Strength in FRP Pipes after Impact Damage

Acoustic Emission (AE) has proven to be a useful tool in the monitoring of fiberglass pressure vessels. The ASME Piping and Pressure Vessel Code (subsection X) implements AE as an approved method for quality control and in service testing of fiberglass pressure vessels, making it an accepted technique for the evaluation of fiber composite structures. This article presents the result of AE monitoring of fiber reinforced plastic (FRP) pipes after impact damage has incurred. The results from these tests indicate that AE can be used as a tool to predict the level of damage incurred in the pipes after impact and during pressurization. The use of the Felicity Ratio as the benchmark for evaluation is presented as the key evaluating value.     

云母粉表面改性提高云母纸拉伸强度的研究

利用硅烷偶联剂"分子桥"作用对云母粉进行表面处理,通过自乳化改性的环氧树脂和聚丙烯酰胺,使云母粉表面桥联的环氧基团发生交联反应,显著提高云母纸拉伸强度。结果表明:当硅烷偶联剂、改性环氧树脂、聚丙烯酸胺的质量分数分别为0.5%、1.0%、0.5%时,云母纸拉伸强度由72.17 N/m提高到151.3 N/m。硅烷偶联剂水解产生的硅羟基与云母表面的羟基发生化学键的结合,另一端的氨基与改性环氧树脂中的环氧基团反应,增强了改性环氧树脂对云母表面的结合力。     

Use of a Fracture Surface Cleaning Method to Evaluate Elevated Temperature Cracking in Steel

Journal of Failure Analysis and Prevention - The nature of cracking during continuous casting of steel strip was investigated. Samples removed from steel strip for fractographic analysis were...     

Tensile Strength Evolution and Damage Mechanisms of Al–Si Piston Alloy at Different Temperatures

The Al–Si piston alloys always bear different temperatures because of its peculiar component structure and service condition. Therefore, the tensile strength, elongation to fracture, and corresponding damage mechanisms of Al12SiCuNiMg piston alloys (ASPA) have been investigated with in situ technique at different temperatures. The tensile properties show two‐stage tendencies: the former stage (25–280 °C) is determined by easily broken phases with inherent brittleness (such as primary Si), and the fracture behavior presents rapid brittle fracture after reaching the critical stress (about 430 MPa, based on in situ technique and the elastic stress field model). The later one (280–425 °C) is dominated by particles debonding and θphase coarsening. The plastic deformation behavior, dynamic recovery, and flow process become more significant on account of thermal activation. The Considère criterion h = K indicates that the transition of damage behaviors from insufficient local strength to insufficient matrix strength and the corresponding failure model shifts from brittle to ductile fracture. Based on the damage mechanisms, the elastic field model and thermal activation relation model have been established to characterize the strength of the ASPA at different temperature ranges.

     

The Use of Surface Analysis Techniques to Determine the Route of Manufacture of Tablet Dosage Forms

ABSTRACT

Analytical methods for determining the manufacturing process of tablet dosage forms have not been previously reported. The use of surface analysis techniques in particular X-ray Photoelectron Spectroscopy and Time of Flight Secondary Ionization Mass Spectrometry will be described and a model proposed which allows the prediction of the route of manufacture in calcium phosphate and cellulosic-based tablet formulations. Results of the application of this model to evaluate prototype tablet formulations prepared by wet granulation or direct compression will be reported. Strengths and limitations of the model will be discussed.     

CFRP筋拉伸强度预测模型评价及应用

在初步建立CFRP筋拉伸强度预测模型基础上,对该模型典型因子影响材料强度权重进行研究评价,根据结果提出CFRP筋制备过程中强度补偿机制。结果表明:典型因子碳纤维拉伸强度(σf)和体积分数(Vf)对CFRP筋拉伸强度影响最为显著(影响率为39.1%~46.7%和43.5%~52.6%),是决定CFRP筋拉伸性能的最重要因素。公称直径(D)对CFRP筋拉伸强度存在一定程度影响(影响率7.1%~15.4%)。基体树脂强度(σm)对CFRP筋拉伸强度影响不明显(影响率0.3%~1.0%),相比其他三种因素,可近似忽略。依据预测模型典型因子强度补偿规律,可较方便推测CFRP筋组分碳纤维强度及体积分数参数。     

玄武岩纤维表面硅烷偶联剂接枝率对环氧树脂复合材料界面强度及力学性能的影响

为提高玄武岩纤维(BF)增强环氧树脂(EP)复合材料的力学性能,通过接枝硅烷偶联剂KH550来提升BF与EP之间的界面强度。采用衰减全反射红外光谱、X射线光电子能谱仪、原子力显微镜、扫描电子显微镜、界面剪切强度测试和拉伸测试研究BF表面KH550的接枝率对复合材料界面粗糙度、界面强度及拉伸强度的影响。结果表明,KH550的成功接枝可以增加BF的表面粗糙度及复合材料的界面强度;随着KH550接枝率的增加,BF表面形貌呈现“光滑-粗糙-光滑-粗糙”的变化过程,复合材料的界面强度及力学性能也呈现先增大后减小的趋势。当KH550接枝率达到5%～6%时,KH550-BF表面均匀光滑,复合材料的界面强度和拉伸强度达到最大,分别为48 MPa和298 MPa。当接枝率超过6%,过量的KH550在BF表面的不均匀分布形成结构缺陷和应力集中,进而导致复合材料界面强度和力学性能的降低。     

Statistical Tensile Strength for High Strain Rate of Aramid and UHMWPE Fibers

Technora,madefromaramidfibersandsome whatsimilartothecommonlyknowKevlar,and Ultrahighlyorientedhighmolecularweightpolyeth ylene UHMWPEfibersarealloftenusedinflexible armourapplicationsandhencesubjectedtohighrates ofloading.Theutilizationoftheirreinforcedcom positesarmourincertainballisticapplicationsisin creasinglypreferredoverconventionalrigidmetalar moursystemsbecauseofitssuperiorstrength to weightratioandflexibility.Todate,thedesignand developmentofsuchfabricarmoursystemshave largelybeen…     

a－Si：H表面键合光敏染料及其光电导

本文报导了用低温等离子体法使ａ－Ｓｉ：Ｈ表面活化，经多步化学反应，将３种菁键合于其表面，并经激光拉曼光谱和Ｘ－光电子能谱表征。测定了键合染料的ａ－Ｓｉ：Ｈ的吸收光谱和光电导。结果表明，光敏染料可使ａ－Ｓｉ：Ｈ敏化，改善其光吸收和光电导。     

路用水性环氧树脂的拉伸强度预测和极值寻优

为实现路用水性环氧树脂力学参数极值寻优,以进一步科学优化其材料组成及配比,基于不同类型原材料自身属性及其掺量的调控,制备了一系列路用水性环氧树脂;以拉伸强度为例,开展了力学参数标定试验并获取了75组有效数据,以此构建了基于小样本数据的传统多元回归方程、典型前馈式及反馈式神经网络等不同预测模型,对比分析了不同模型的拟合效果与预测精度;采用遗传算法对优选的预测模型进行优化,实现了拉伸强度极值寻优功效,回溯确定了原材料各项属性及掺量的最佳取值,为路用水性环氧树脂材料组成及配比的科学优化提供有益借鉴.结果表明:相比五元非线性回归方程和反向传播(Back Propagation,BP)模型,Elman模型的预测误差降低了25. 94% ～37. 5% ,具有较好的预测精度和稳定性;综合考虑预测精度和运算速度,推荐采用Elman神经网络(6×4×1)作为路用水性环氧树脂拉伸强度的预测模型;采用遗传算法可快速获得最优拉伸强度和相关材料组成及配比,降低试验成本,但其准确度仍需进一步优化.     

35CrMoV钢硬度概率分布与抗拉强度设计许用值预测分析

采用最小二乘法和K-S检验方法进行分布拟合检验,在求得35CrMoV钢硬度和抗拉强度正态分布的基础上,对其硬度和抗拉强度关系进行相关性研究,运用线性相关系数判断硬度和抗拉强度之间具有强正线性相关关系.运用正态代数运算方法,从硬度的概率分布估计抗拉强度的概率分布,预测其设计许用值,并与从抗拉强度概率分布计算得到的设计许用...     

矿渣粉比表面积及粒度分布对水泥强度的影响

采用勃氏透气仪和激光粒度分析仪,对矿渣粉试样进行比表面积和颗粒群粒度分布的测试,研究矿渣粉比表面积及粒度分布对水泥强度的影响。结果表明:矿渣粉总体颗粒越细,则比表面积越大,特征粒径越小,颗粒群分布越宽;细颗粒含量(小于5μm)越多的矿渣粉,其比表面积越大,水泥砂浆的早期强度就越高。     

Use of Eddy Current Conductivity and Hardness Testing to Evaluate Heat Damage in Aluminum Alloys

Aluminum alloys are heat treated to provide optimal material properties for use in a variety of applications. However, when exposed to abnormally high temperatures, an evaluation must be performed to determine if the aluminum component has been compromised. Nondestructive evaluation of aluminum alloys, by means of electrical conductivity and hardness tests, can assist in determining the condition of the part. These techniques require experience and engineering judgment to properly interpret the data produced in order to determine whether a part needs to be replaced. This article will elaborate on issues with these nondestructive techniques to help diagnose the condition of aluminum alloys exposed to high temperatures.     

Hierarchical Interconnected NiMoN with Large Specific Surface Area and High Mechanical Strength for Efficient and Stable Alkaline Water/Seawater Hydrogen Evolution

NiMo-based nanostructures are among the most active hydrogen evolution reaction(HER) catalysts under an alkaline environment due to their strong water dissociation ability. However, these nanostructures are vulnerable to the destructive effects of H₂ production, especially at industry-standard current densities. Therefore, developing a strategy to improve their mechanical strength while maintaining or even further increasing the activity of these nanocatalysts is of great interest to ...     

Analysis Comparative of Methods to Evaluate Consolidation Mechanisms in Plastic and Viscoelastic Materials Used as Direct Compression Excipients

In order to better explain the mechanisms of tablet formation, there is now a greater tendency to investigate particle deformation rather than bulk deformation of the powder bed.

In this sense, measurements of static indentation in tablet to determine compressibility and compactability of powders were used. In this work this method, using as hardness testing a pyramid instead of a ball into the surface of the tablet under test, is compared to Heckel plots using ejected tablet method. Also, bonding index, absolute differences between indentation hardness of tablet surfaces and force-displacement curves were used to establish behaviour of excipients that undergo compression deform plastically and viscoelastic excipients with tendency to deform plastically until applied pressure was exceeded.