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布氏和维氏硬度试验压痕的正确测量,直接影响到被测试件的硬度值,因之不容忽视。常用的测量方法有: 1.单线测量——测量线移动法此种测量压痕的方法是先使测量线在压痕之左逐渐逼近压痕左缘,直至相切,记下读数(d_1)。参看图1。然后向右移动测量线,到与压痕之右缘相切为止(对维氏硬度压痕,测量线必须与对角线垂直)。再记下第二次读数(d_2),两次读数之差(d=d_2-d_1)即为压痕的直径(或对角线长)。由于只使用一条刻度线,故误差因素少。但测量线要移动整个压痕 相似文献
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《测试技术学报》2016,(2)
评价气相沉积硬质薄膜的韧性具有重要的工程意义.本文讨论了压入法评价硬质薄膜韧性的原理、方法和参数选择.压入法的原理是载荷导致裂纹形核、扩展,最终形成压痕周围的径向裂纹,而断裂韧性和裂纹之间存在对应关系.压入法的方法是比较压痕形貌特征,其主要影响因素有基体和载荷.对于韧性基体(如金属),小载荷时硬质薄膜与金属同步塑性变形;大载荷下薄膜破裂,但这种情况可能是结合失效破裂,并不反映薄膜的韧性.对于脆性基体(如硅片),小载荷时裂纹会在Si片中形核,并扩展到薄膜中,形成压痕对角线径向裂纹;大载荷时薄膜会严重破裂.定量评价薄膜韧性时,一般采用硬质薄膜/Si片体系,以0.98~9.8N载荷压入脆性基体,采用纳米压入仪测定薄膜的硬度和弹性模量,采用显微镜测量径向裂纹的长度,利用Lawn公式计算得到断裂韧性值. 相似文献
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《中国测试》2015,(6):12-17
该文以典型陶瓷材料Si3N4和Al2O3为例,分别应用材料弹性模量仪器化压入测试中的两种代表性方法——Ma方法和Oliver-Pharr方法 ,对两种材料的仪器化压入测试结果进行计算。结果表明:Ma方法对陶瓷材料弹性模量的测试误差小于Oliver-Pharr方法。利用两种不同面角的四棱锥压头分别对Si3N4和Al2O3材料进行仪器化压入实验,并结合有限元数值分析方法,确定Si3N4材料的塑性参数(屈服强度σy=7 800 MPa和应变硬化指数n=0.02)和Al2O3材料的塑性参数(屈服强度σy=4 100 MPa和应变硬化指数n=0.025),从而为进一步研究陶瓷材料力学性能参数仪器化压入识别方法提供一定的理论基础。 相似文献
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为了研究维氏压痕裂纹对常压固相烧结碳化硅陶瓷(SSiC)材料力学性能的影响, 通过扫描电镜观察了0.1~100 N的压痕载荷下产生的表面裂纹及裂纹剖面的状况, 并测试了相应载荷下的力学性质, 探讨了压痕法测量SSiC材料硬度、韧性等力学性质的适当压力载荷. 结果表明, SSiC材料压痕裂纹起始的临界压力载荷介于0.1~0.2 N; 当压痕载荷小于0.5 N时, 裂纹尺寸小于5 μm, SSiC材料的平均弯曲强度受影响程度较小. 此外, 当压痕载荷为10 N以上时, 压痕法测得的维氏硬度值趋近定值, 且所得到的裂纹是半圆形裂纹, 因此, 10 N为采用压痕法准确测量SSiC材料硬度及韧性的最低压痕载荷值. 相似文献
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基于AFM纳米硬度测量系统的实验 总被引:1,自引:0,他引:1
为了解决用AFM自身压痕软件进行纳米硬度测量时无法直接获得载荷-压深曲线和由于受到扫描陶管扫描范围的限制而进行多点压痕实验范围有限的问题,建立了三维微动工作台和原子力显微镜相结合的纳米压痕硬度测量系统.基于该系统,对单晶薄膜材料进行了单点压痕实验,得出该系统适合进行纳米硬度测量的结论;并对薄膜材料的纳米硬度和弹性模量进行了分析,讨论了尺寸效应对两者的影响.另外,进行了40×40的点阵压痕实验,得到了材料整个压痕面的三维形貌图和三维硬度图. 相似文献
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《International journal for numerical methods in engineering》2018,113(9):1488-1506
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. 相似文献
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Standards are the basis for production enterprises to organize production ex-factory inspection trade 《中国标准化(英文版)》2008,25(1):24-25
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.…… 相似文献
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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. 相似文献
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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.…… 相似文献
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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. 相似文献
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C. Qihong W. Zhan‐Wen J. Yi J. Yehua L. Fei F. Hanguang 《Materialwissenschaft und Werkstofftechnik》2014,45(7):582-590
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. 相似文献
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Dimiter Hadjistamov 《材料科学与工程:中英文B版...》2019,(2):56-65
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 ... 相似文献
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《中国标准化(英文版)》2014,(4)
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 相似文献
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《中国标准化(英文版)》2014,(5)
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. 相似文献