纳米SiO2改性上浆剂对炭纤维复合材料界面性能的影响

利用单纤维碎裂法，三点短梁法，扫描电镜（SEM）和动态力学热分析（DMTA）研究了未上浆炭纤维、环氧树脂乳液上浆炭纤维和经纳米SiO2改性环氧树脂乳液上浆炭纤维增强树脂基复合材料（CFRP）的界面性能。结果表明：炭纤维经改性乳液上浆剂和未改性乳液上浆剂上浆后，与未上浆相比，其单纤维复合材料的界面剪切强度（IFSS）分别提高了79％和41％，复合材料的层间剪切强度（ILSS）分别提高了14％和9％。DMTA图谱显示经纳米SiO：改性上浆的CFRP其损耗角正切（tanδ）较未改性上浆的降低18％，玻璃化温度（Tg）高出5℃。说明上浆剂中添加纳米SiO2可使上浆后的CFRP界面黏结性得到显著增强。     

单丝拉伸断裂法探究上浆剂改性炭纤维与聚碳酸酯的界面黏结性

为了探究不同上浆剂对炭纤维/聚碳酸酯复合材料界面黏结性的影响,采用自制水性聚碳酸酯乳液、聚醋酸乙烯酯乳液、聚氨酯乳液与聚乙烯乳液等上浆剂对炭纤维进行表面改性。采用红外光谱(IR)和热重-质谱联用(TG-MS)仪分析上浆剂的化学结构;采用扫描电子显微镜(SEM)、X射线光电子能谱仪(XPS)与热重分析仪(TG)等研究上浆改性炭纤维的表面结构。为了量化地分析炭纤维与聚碳酸酯的界面剪切强度,采用单丝拉伸断裂法得到界面剪切强度。结果表明,水性聚氨酯乳液上浆改性后的炭纤维与聚碳酸酯的界面剪切强度最高(29.19 MPa),这是由于聚氨酯中含有较多的氨酯键,可与树脂形成较多的氢键。相对而言,水性自制乳液与聚醋酸乙烯酯乳液涂层后的炭纤维与聚碳酸酯之间只有物理吸附作用,因此界面黏结性略弱。     

炭纤维乳液上浆剂

采用转相乳化法，选用不同的混合乳化剂对环氧树脂AG－80进行乳化。通过静置沉淀法，比较不同混合乳化剂对其乳化的影响，结果表明乳化效果最好的是乳化剂1601与NP－10的混合乳化剂。粒径分析结果显示乳液的最可几粒径为934．1nm时，乳液稳定性较好。上浆处理后，单纤维复合材料的界面剪切强度较未上浆时有所提高，说明用该上浆剂处理，不仅可达到保护炭纤维表面的目的，而且可以改善炭纤维与基体树脂间的界面粘结。     

碳纳米管改性乳液上浆剂对炭纤维复合材料界面性能的影响

采用碳纳米管改性环氧树脂乳液上浆剂和未改性上浆剂对聚丙烯腈(PAN)基炭纤维进行表面上浆。通过激光粒度仪研究两种乳液的稳定性。采用扫描电子显微镜(SEM)、X-射线光电子能谱仪(XPS)与原子力显微镜(AFM)研究未改性及改性上浆炭纤维的表面结构,并用HM410界面评价装置研究炭纤维复合材料的界面性能。结果表明,碳纳米管改性后,乳液稳定性得到提高。上浆后,炭纤维表面粗糙度增加73.1%,同时接触角减小11.9%,且炭纤维表面的含氧官能团含量增加45.96%。此外,改性炭纤维复合材料的界面性能得到明显改善。当碳纳米管在上浆剂中质量分数为0.75 w t%时,炭纤维单丝的界面剪切强度较之未改性炭纤维提高14.7%。     

纳米SiO2改性炭纤维乳液上浆剂的性能评价

采用纳米SiO₂改性环氧树脂乳液上浆剂和未改性乳液上浆剂对聚丙烯腈(PAN)基炭纤维进行表面上浆。通过静置沉淀法和光学显微镜评价了两种乳液的稳定性。利用扫描电子显微镜(SEM)、 X射线能谱仪(EDS)、 原子力显微镜(AFM)和动态接触角测试仪(DCAA)研究了未上浆、 未改性和改性上浆炭纤维的表面性能, 并用单纤维碎裂法探讨了上浆剂对炭纤维与环氧树脂界面黏结的影响。结果表明: 未改性和经纳米SiO₂改性的两种乳液粒径较小, 稳定性较好, 而前者优于后者。上浆后, 炭纤维表面的粗糙度和表面能都增大, 而且最大值出现在改性乳液上浆炭纤维的表面。改性乳液上浆单纤维复合材料拥有最大的界面剪切强度(IFSS), 比未改性上浆的高出27.2%; 改性上浆炭纤维与基体的调和平均黏结功(W(h)_a )和几何平均黏结功(W(g)_a )也分别高出未改性上浆的12.7%和11.7%。      

炭纤维特性与炭纤维/环氧树脂界面断裂能关联分析

采用基于WND(Wagner-Nairn-Detassis)能量模型的单丝断裂法,测试了5种国产炭纤维、2种国外炭纤维与航空结构用环氧树脂复合体系的界面断裂能,通过SEM,AFM,IR以及XPS等手段分析了7种炭纤维的表面物理化学特性,并研究了炭纤维特性与界面断裂能的关联。结果表明:对于所研究的炭纤维/环氧树脂体系,去除炭纤维表面上浆剂后界面断裂能下降,说明上浆剂可以在一定程度上提高界面的韧性。此外,实验范围内,纤维拉伸强度较高时,测得的界面断裂能较高,炭纤维表面粗糙度较高时,测得界面断裂能较高,说明纤维拉伸性能和表面粗糙度对界面韧性有重要影响,而与这两种因素相比,上浆剂的种类影响相对较小。研究结果为高性能国产炭纤维的研发和炭纤维/树脂匹配性的评价提供了重要的实验数据。     

聚氨酯上浆剂对炭纤维增强聚氨酯复合材料界面性能的影响（英文）

经阳极氧化的炭纤维丝束用水性聚氨酯进行上浆，考察上浆剂对炭纤维增强聚氨酯复合材料界面性能的影响，并结合元素分析、官能团分析、热重分析和示差扫描热分析进行机理研究。结果显示，上浆剂可以显著提高复合材料界面性能。层剪强度从氧化后的39.5 MPa提升到上浆后的46.4 MPa，提升17.5%。上浆的炭纤维经170°C热处理后层剪强度进一步提高到50.8 MPa。这归因于上浆剂与炭纤维表面的含氧官能团进行反应形成化学键，而上浆剂与基体以氢键相互作用。经进一步热处理后，上浆剂的封端剂脱除，释放出异氰酸酯与基体中的氨基甲酸酯反应生成尿基甲酸盐。因此，此水性聚氨酯上浆剂提高了炭纤维增强聚氨酯复合材料的界面性能。     

炭纤维表面性质及上浆剂对炭纤维聚碳酸酯复合材料界面性能的影响

通过对比未处理炭纤维、氧化炭纤维、商业化环氧树脂用炭纤维和实验室用聚氨酯及环氧树脂自上浆炭纤维的表面性质和其增强聚碳酸酯层间剪切强度,研究炭纤维表面性质与上浆剂对界面结构与性能的影响。结果表明,未处理炭纤维表面官能团与树脂的浸润性最小,层剪值最低为38.1 MPa。氧化纤维表面官能团增加,浸润性提高,层剪值提高到50.6 MPa。商业化环氧树脂用炭纤维表面官能团与树脂浸润性相比氧化纤维明显提高,层剪值相当,为50.8 MPa。说明浸润性是强界面产生前提,但不是充分条件。自上环氧浆炭纤维复合材料的层剪值相比商业炭纤维更低,约为31.7～39.5 MPa,而聚氨酯上浆炭纤维表面官能团与浸润性跟商业化环氧树脂用炭纤维相当,但层剪值提升18.9%,为60.4 MPa。说明界面结合强度提高的原因更依赖于氨酯键与炭纤维表面及聚碳酸酯树脂基体均能产生强的化学作用。     

纳米SiO2改性乳液上浆剂对炭纤维抗拉强度的影响

利用Weibull统计分布分析了上浆对炭纤维单丝抗拉强度的影响。通过扫描电镜（SEM）观察和X射线能谱仪（EDS）分析了上浆前后炭纤维表面和截面的结构形貌及表面元素组成。结果表明：当纳米SiO2粒子与上浆树脂的质量比为0．5％时，上浆炭纤维单丝的抗拉强度最高，增幅达10．1％；Weibull参数m值最大，强度的分散性最小。EDS显示了改性上浆炭纤维表面Si元素含量增大。上浆炭纤维比未上浆的表面较均匀，纹理沟槽变浅；截面凹凸不平，呈现一定的韧性断裂特性。说明上浆剂中添加纳米SiO2粒子可以明显提高上浆炭纤维的强度。     

聚乙二醇改性环氧乳液碳纤维上浆剂的研制

用聚乙二醇(PEG)在催化剂过硫酸钾作用下与环氧树脂反应, 制得自乳化环氧树脂乳液。通过红外光谱表征改性环氧的结构, 并比较不同实验方案下乳液的稳定性, 探讨了反应原料、合成工艺等因素对实验结果的影响, 确定了最佳实验方案; 用热分析实验表征上浆剂的热稳定性, 接触角测试表征上浆剂乳液的浸润性, 单丝碎裂实验测定界面剪切强度。结果表明, 使用双酚A环氧树脂及PEG1000在80~120 ℃反应制得的乳液稳定性最好, 上浆剂的热稳定性和浸润性良好。用实验制得的乳液对碳纤维上浆, 单丝界面剪切强度比上浆前提高33.48%, 碳纤维毛丝量减少。      

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.