先进复合材料中主要缺陷分析

本文重点介绍了复合材料中主要缺陷的各类,分析了缺陷产生的原因,对主要缺陷对性能的影响、缺陷的控制方法、缺陷的无损检测方法及其进展进行了综述。     

玻璃的脆性(三)

玻璃的缺陷可分为纳观缺陷、微观缺陷和宏观缺陷。纳观缺陷为纳米尺度的缺陷,指玻璃结构缺陷,包括微相、微不均、配位不全,空穴等。微观缺陷指微米尺度缺陷,主要为玻璃表面Griffith裂纹。宏观缺陷为玻璃制造中产生的缺陷,如气泡、结石、条纹,以及使用过程中的损伤。这些缺陷的存在增加玻璃的脆性。描述了玻璃表面Griffith裂纹的尺寸、分布以及形貌。     

TFT-LCD基板玻璃粘附缺陷成因及控制

玻璃粘附缺陷是TFT-LCD基板玻璃生产过程中一种常见缺陷,该缺陷的存在会对基板玻璃成品在其后续加工中产生相关对应缺陷,为此在基板玻璃半成品生产过程中应予以严格控制。针对生产过程中各类玻璃粘附相关缺陷的产生成因、对策方法及对策结果进行了详细阐述。缺陷分析主要手段为缺陷显微镜观察摄像及测量。     

RTM工艺中气泡形成及消除研究

总结了关于RTM（树脂压铸）工艺中气泡缺陷的文献报道，对RTM中气泡缺陷的形成机理、影响因素及各研究者提出的消泡方法、理论和模型进行了概述，同时对RTM工艺中气泡缺陷的研究现状给予充分关注，并对RTM缺陷研究的未来方向进行了展望。     

通过气泡成分分析解决超白浮法玻璃生产中的气泡缺陷

气泡是玻璃生产中最常见的玻璃缺陷之一,由于它的大小、密度、位置的不确定性,增加了对气泡缺陷来源诊断的难度。超白浮法玻璃生产中气泡更是影响玻璃质量的主要缺陷,通过测定气泡中气体的组成含量,可以较准确、快速地判断该缺陷产生的根源,从而采取有效措施消除缺陷。     

彩色显像管玻璃中的气泡

气泡是显像管玻璃生产中最主要的缺陷,本文主要论述了彩色显像管玻璃中气泡产生的原因,并对玻璃中气泡缺陷的分析、判定以及减少气泡缺陷的措施作了简要评述.     

搪瓷讲座(六)

严格地说,瓷釉缺陷和搪瓷缺陷并不是一回事。搪瓷过程中或搪瓷以后出现的搪瓷缺陷,可能起源于琅粉(瓷釉缺陷)、钢板(金属缺陷)、搪瓷工艺(工艺缺陷)。这样,常使搪瓷厂中寻找造成这些缺陷的原因发生困难。 在搪瓷过程中发生的或搪瓷后辨认出来的缺陷,虽然在找到其原因以前,干扰了正常的     

涂装涂层／涂层体系缺陷（弊病）的分析及处理（Ⅰ）

叙述了缺陷（弊病）的基本概念,并对各种缺陷（弊病）进行了分类;分析了涂装各阶段缺陷（弊病）的表现形式,探讨了企业在涂装过程中分析、解决缺陷（弊病）的流程和方法。     

螺旋缝埋弧焊管超声波脉冲反射法检测技术

螺旋缝埋弧焊钢管（SSAW）是常见的油气输送管之一。随着我国西气东输工程的开展,已经攻克了螺旋缝埋弧焊管生产工艺中的诸多难点。但在焊管的实际生产中,由于设备配置不均衡、工艺落伍等原因,总是会产生一些缺陷。由于焊缝中裂纹、未焊透、未熔合等面积型缺陷直接减小了焊缝截面,因此,这些缺陷是典型的危险型缺陷。本文针对螺旋缝埋弧焊管中常见的缺陷,采用脉冲反射法和超声检测技术,对钢管缺陷进行了定位和定量研究。     

化工设备焊接中常见的缺陷及其控制措施

化工设备焊接中出现缺陷,轻则导致设备的损坏,重则危及人身安全。本文简要介绍了化工设备的焊接缺陷控制的意义,并深度分析了化工设备焊接中常见的焊缝外部、焊缝内部缺陷及其防止和修补策略。     

On the nature of defects and mechanism of their formation in thin borophosphosilicate glass layers produced by vapor deposition upon fabrication of integrated circuits

The data on the defects formed in vapor-deposited thin borophosphosilicate glass layers upon their interaction with surrounding atmosphere are analyzed. The formation, growth, and evolution of defects in glasses are studied. The classification of defects is proposed, and the concentration ranges of the existence of the specified defects are determined. The nature of defects in the borophosphosilicate glass layers is discussed, and the mechanism of their formation is advanced.     

On the nature of defects and mechanism of their formation in thin borophosphosilicate glass layers produced by vapor deposition upon fabrication of integrated circuits

The data on the defects formed in vapor-deposited thin borophosphosilicate glass layers upon their interaction with surrounding atmosphere are analyzed. The formation, growth, and evolution of defects in glasses are studied. The classification of defects is proposed, and the concentration ranges of the existence of the specified defects are determined. The nature of defects in the borophosphosilicate glass layers is discussed, and the mechanism of their formation is advanced.     

缺陷是碳纤维的致命伤

着重论述了缺陷产生的原因及其对碳纤维抗拉强度的影响。碳纤维属于脆性材料,抗拉强度受控于各类缺陷;缺陷是碳纤维的致命伤。抗拉强度与缺陷之间的关系遵循格拉菲斯微裂纹理论;缺陷随机分布,服从最弱连接理论;缺陷愈小和愈少,抗拉强度愈高、CV值愈小。指出:提高碳纤维抗拉强度的基本思路是控制各类缺陷的产生,减小缺陷尺寸,减少缺陷数目;提高碳纤维力学性能的治本措施就是在于消除各类缺陷。     

有机晶体缺陷的研究进展

有机晶体存在裂纹、包裹体、位错和孔洞等缺陷,常引起杂质包藏、产品质量下降、光学和机械性能降低等问题。含有大量缺陷的晶体在产品后处理阶段和使用阶段均面临诸多困难,近年来已成为晶体学研究学者们关注的热点。针对在有机晶体缺陷研究中尚无综合性的报导,阐述了晶体缺陷的类型与形成机理,详细讨论了晶体缺陷的检测方法和表征手段,综述了减少有机晶体缺陷形成的调控手段以及晶体缺陷和晶体形态调控方法在炸药、非线性光学材料、半导体材料晶体性能改进等方面的应用。     

A molecular dynamics investigation of the torsional responses of defective single-walled carbon nanotubes

The buckling behavior of defective single-walled carbon nanotubes (CNTs) under torsion is investigated by using molecular dynamics simulations. Various kinds of defects including vacancy defects (monovacancy, bivacancies and line) and topological defects such as Stone-Thrower-Wales are considered. The effect of initial defects on the torsional properties is closely examined. The simulation results show that the torsional capacity is strongly dependent of the type of defects, chirality and temperature. The reduction in the torsional capacity is greater for CNTs with vacancy defects than CNTs with topological defects. Armchair CNTs have higher shear modulus and critical torques and are less sensitive to the presence of defects when compared to their zigzag counterparts. Higher temperatures trigger bond reconstructions in defective CNTs and bring relief to the negative effects of the defects, thereby improving the torsional capacities of the defective CNTs. Thus, the deterioration of the torsional capacity induced by defects can be mitigated through thermal treatment.     

Defects in banded spherulites of polymers

In order to investigate the detailed structure of a banded spherulite observed by polarized light microscopy, we develop a new image processing technique that can visualize defects (band defects) in the concentric bands and determine the growing directions of crystals everywhere in a spherulite. This technique is applied to a banded spherulite of poly(vinylidene fluoride) and reveals that the spherulite has many defects (colliding defects), on which crystals collide with neighboring ones. It is found that the band defects are included in the colliding defects. The number of colliding defects increases linearly with the radius to give a constant density. Between the defects, the orientations of crystals are well correlated to form a coherent area. On the basis of these findings, a mechanism of the formation of the coherent band pattern is discussed.     

木器漆膜表面状态缺陷及解决对策

木器漆膜表面经常出现各种缺陷的原因， 对改善其表面状态用的各类助剂作了论述。     

RTM碳纤维复合材料宏观缺陷超声表征及分析

以RTM碳纤维复合材料为研究对象,通过超声特征扫描成像系统对大量试样进行检测,由理论可知,超声波的反射特性会随着宏观缺陷类型的不同而不同。首先从理论上分析各缺陷的反射特性,然后找出不同的宏观自然缺陷,归纳总结各种缺陷对应的图像特点,再采取破坏方法对试样进行切割、打磨,通过显微镜观察不同缺陷形貌特征。结果表明,超声特征扫描成像系统可以检测并分辨出不同的宏观缺陷,通过观察缺陷金相图可知不同类型缺陷形貌特征也各不相同,为RTM碳纤维复合材料宏观缺陷检测及形貌研究提供了一种可行方案。     

聚丙烯制品外观缺陷及解决措施

介绍聚丙烯制品常见的外观缺陷，从理论上分析各种缺陷产生的原因，并结合实际讨论注塑工艺条件、模具结构、设备对聚丙烯制品外观质量影响。结果表明，通过调整注塑工艺条件、改变模具结构及设备状况即可避免聚丙烯制品表面缺陷的出现，改善制品外观质量。     

Defects classification and failure modes of electrofusion joint for connecting polyethylene pipes

As electrofusion (EF) technology is widely used in connecting polyethylene (PE) pipes and other plastic pipes or composite pipes, research in safety assessment of EF joints has been of major concern. EF joints with defects are very common in practical applications. These defects may greatly reduce the mechanical performance of the EF joints and threat safety running of the pipeline system. To evaluate hazard of these defects and provide a basic understanding for the failure mechanism of EF joints, a comprehensive study on defects and failure modes is conducted in this work. The defects in EF joints are classified into four categories: poor fusion interface, over welding, voids, and structural deformity. The forming reasons of these defects are analyzed in detail. The mechanical properties of EF joint containing these defects are investigated by conducting peeling tests and sustained hydraulic pressure tests. Test results show that there are three main failure mode of EF joint under inner pressure, that is, cracking through the fusion interface, cracking through the fitting, and cracking through copper wire interface. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012