SWRH82B高碳盘条显微组织对断裂韧性JIC的影响

采用单试样法测试了用三种不同工艺生产的SWRH82B高碳盘条的断裂韧性JIC值,计算了材料的KIC值,并对珠光体层片间距进行了测定,探讨了其组织对断裂韧性JIC值的影响。试验结果表明,SWRH82B高碳盘条的珠光体层片间距越细小,JIC值越大;SWRH82B高碳盘条的断裂韧性JIC为14．8～17．3KJ／m,KIC为56．0～60．5MPa／m^1/2。     

SiCp-WSi2/MoSi2复合材料的室温力学性能

为了提高MoSi2的室温断裂韧性,将Si、Mo、W和C四种粉末混合后通过"原位反应热压"一次热压工艺制备了两种不同体积配比的SiCp-WSi2/MoSi2复合材料试样,测定了复合材料试样和纯MoSi2试样的室温.断裂韧性(KIC)与显微硬度(HV);采用X射线衍射(XRD)、扫描电镜(SEM)等方法研究了该工艺下试样的结构、组织以及断口形貌与断裂韧性问的相互关系.结果表明,SiC的复合化和W元素的合金化能使SiCp-WSi2/MoSi2复合材料晶粒细化,硬度、室温断裂韧性比纯MoSi2明显提高,断裂韧性最高值达5.88 MPa·m1/2.并对复合材料的硬化、韧化机理分别进行了分析.     

FCVI工艺制备了SiCf／SiC复合材料结构与性能研究

采用热梯度制流动力气相渗积（FCVI）工艺制备SiCf/SiC复合材料,测试了复合材料的性能,制备了复合密度达到2．3g/cm^3,强度为291MPa,断裂韧性为11.4MPa.m^1/2,运用SEM,TEM,X射线衍射等分析手段对复合材料的微观结构进行了表征,结果表明：渗积的基体材料为β－SiC,晶粒尺寸为亚微米级,结晶度良好,通过对断口形貌的观察,分析了增韧机制。     

金属玻璃基复合材料的制备及断裂韧性测试

采用铜模吸铸法制备了(Zr0.55Al0.1Ni0.05Cu0.30)100-xTix(x=0、2、4、6、8)板状哑铃型金属玻璃基复合材料试样。用X射线衍射(XRD)、岛津AG-10TA万能材料力学试验机和JSM-6700F场发射扫描电子显微镜(SEM)对试样的组织结构以及断裂韧性进行了测试。结果表明,当x=0、2、4时,试样为非晶-晶体复合材料,当x=6、8时,试样为晶体材料。表明通过调整Ti的含量可以制备出金属玻璃基复合材料。采用三点弯曲法测定了复合材料的断裂韧性,当x=0、2、4时,试样的断裂韧性KIC值分别为10.529、5.142和3.446MPa.m1/2。     

硬质合金断裂韧性的测试新方法

在选择应用脆性、高耐磨材料时,需要了解材料的硬度、横向断裂强度及断裂韧性等参数.特别是在金属切削工具领域,良好的加工性能和长久的使用寿命是关键的性能参数.在测量硬质合金断裂韧性KIC时,Leoben大学研究发现,用通常的Palmqvist方法测量的结果与疲劳实验测出的KIC值有偏差,特别是在对高硬度合金进行测量时.奥地利普兰西硬质合金中心研究出一种新的测试硬质合金KIC的方法.这个方法所用的试样先要预制裂纹,并可以控制裂纹的扩展.所用的是三点单边梁V形内切口试样,如图1所示.     

SHS／PHIP法制备Ti3AlC2陶瓷的力学性能

测试了用SHS/PHIP法制备出Ti3AlC2陶瓷的弯曲强度、断裂韧性、维氏硬度以及压缩性能.实验结果表明,用SHS/PHIP法制备出的Ti3AlC2陶瓷具有较高的室温弯曲强度(330.8MPa)、断裂韧性(5.7MPa·m1/2)和较低的维氏硬度(2·9GPa).Ti3AlC2陶瓷的室温变形抗力为823MPa,并且变形温度越高,变形抗力越小,塑性特征越明显.较低维氏硬度和良好的力学性能赋予了用SHS/PHIP法制备出Ti3AlC2陶瓷非常好的加工性能.     

聚硅氧烷先驱体转化制备低成本Si—O—C陶瓷基复合材料

研究了廉价聚硅氧烷的交联与裂解情况，并以其为先驱体转化制备Si-O-C陶瓷基复合材料，结果表明，在氯铂酸的催化下，聚硅氧烷与二乙烯基苯可以交联固化，当聚硅氧烷／二乙烯基苯摩尔比为1：0．5时，陶瓷产率达60．52％，经6次浸渍－交－裂解过程制备出碳纤维三维编织物增强陶瓷基复合材料，其密度达到1.59g/cm^3，弯曲强度达到321MPa，断裂韧性达到9.38MPa.m^1/2.     

可溶性PPESK/氰酸酯树脂体系的制备与性能

采用热熔法制备了含氮杂萘聚醚砜酮(PPESK)/氰酸酯共混树脂体系。利用断裂韧性和弯曲实验考察了PPESK分子量对共混体系力学性能的影响规律,发现共混体系的临界应力强度因子(KIC)为1.00 MPa.m1/2～1.25 MPa.m1/2,弯曲强度和弯曲模量分别为140 MPa～148 MPa和3.26 GPa～3.30 GPa。使用热变形测试和热失重分析法(TGA)研究了体系的耐热性,共混体系的热变形温度约为266℃,在N2气氛中5%热失重温度为415℃～428℃。对PPESK/氰酸酯树脂体系的介电性能测试结果表明,共混体系的介电常数和介电损耗角正切分别为3～3.2和0.006～0.007。     

三维碳化硅/碳化硅陶瓷基编织体复合材料

采用化学气相浸渗法（CVI）,制备出三维Hi-Nicalon SiC/SiC陶瓷基纺织体复合材料,经30hCVI致密化处理后,复合材料的密度达到2．5g.cm^-3。所研制的三维SiC/SiC复合材料不仅具有较高的强度,而且表现出优异的韧性和类似金属材料非灾难性的断裂特征,复合材料的主要功能力学性能指标为：弯曲强度860MPa,断裂位移1．2mm,断裂韧性41．5MPa.m^1/2,断裂功28．1kJ.m^-2,冲击韧性360.0kJ.m^-2。     

热处理对TC4-DT钛合金组织性能的影响

研究了Ф300mm的TC4-DT钛合金几种热处理工艺参数对显微组织和室温性能的影响。研究表明α＋β区锻造Ф300mm的棒材晶粒较大,低倍呈现模糊晶,局部区域有明显的清晰晶,表明大规格棒材锻造均匀性较差。大规格的棒材＋双重退火热处理后,拉伸性能和断裂韧性均能达到Rm≥825MPa,RP0.2≥750MPa,A（纵向）≥8％,Z≥15％;KIC（T—L）≥90MPa·m1/2,具有良好的强度塑性匹配性能。α＋β相区锻造的Ф300mm棒材经965℃／1h Ac十550℃／6h AC和940℃／1h AC＋570℃／6h AC处理后,疲劳裂纹扩展速率在△K=11MPa·m1/2时,分别达到2．833036×10^-6mm／cycle和7．294209×10^-6mm／cyele。     

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.