气孔结构参数对刚玉质浇注料热导率的影响

本文以铝酸钙水泥(Secar 71)结合刚玉质浇注料为研究对象,通过调整粒度级配(临界粒度为0.088mm和1mm)、热处理温度(分别为1500℃和1600℃)和添加糊精(分别为0、0.5％、1％和1.5％)等方法来改变浇注料试样的气孔结构参数,从而研究其对试样热导率的影响.研究结果表明:试样的显气孔率和气孔中位径均随着热处理温度的升高或糊精含量的增加而增大;当试样的临界粒度增加(0.088mm到1mm)时,因坯体密度提高,烧结更为显著,致使试样的显气孔率变小,气孔中位径增大;试样的常温热导率随显气孔率及气孔中位径的增大而减小,且此变化规律不受临界粒度的影响,临界粒度变化只改变热导率的大小,而并不会改变热导率的变化规律.     

翡翠的鉴定

<正> 翡翠是硬玉为主的多种矿物组成集合体。主要产于缅甸。它以艳丽色彩、美丽的光泽、晶莹剔透的滋润感被人们冠以“玉石之王”之美誉。由于翡翠产量少,价值高,许多不法商人常以其它玉石冒充翡翠,或以低档翡翠经过优化处理冒充高档翡翠欺诈消费者。本文介绍几种鉴别方法,以飨读者。     

苹果酸的鉴定

通过化学分析和分子结构分析相结合的方法,依据一定的推想条件,求得苹果酸的近似分子量,证实了假设条件的叮行性和分子结构判断的准确性。     

塑料薄膜的鉴定

塑料包装薄膜常有好几层,有用二种或三种聚合物混合挤压制成,或者是用粘合剂将各层薄膜粘合起来。亦有这两种方法结合使用的。薄膜中间也可能有隔离层,另外还可能有其它一些加层。     

碧玺的鉴定方法

正长春车先生:在店里看中了一条碧玺,比其他店里便宜很多,颜色鲜艳,可是这样的碧玺是真的吗?我该如何辨别碧玺的真假呢?小编解答:碧玺是仅次于钻石、祖母绿的珍贵矿石,因其颜色多彩绚丽、透明等特色深受人们喜爱。在清代官员的顶戴上都会有一颗碧玺,以象征其官阶、身份。碧玺与玻璃和水晶不同,而且价格要高于它们,所有购     

科技档案的鉴定

本文探讨科技档案鉴定的意义和工作过程，对企业的科技档案鉴定工作提出一些思考。     

浅谈古钱币的鉴定

古钱币鉴定,是一门细致的学科,它需要我们日常知识的积累,注重观察与思考,仔细比较。结合历代的文献资料和前人研究的成果,找出一些可循的、可借鉴的理论依据,从而归纳总结出古钱鉴定中的一般性规律。本文简单介绍几种古钱鉴定的方法。1、看铜质     

洗印拷贝的鉴定

在影片的拍摄及后期洗印加工过程中,会出现各种因素导致拷贝划痕、脏点、干燥斑等损伤,鉴定工作的职责就是要及时找出这些损伤,分析产生的原因并采取预防措施。本文作者根据多年工作实践,总结出多条经验,在此与电影界工作同行分享。     

山珍海味的品质鉴定

山珍海味的品质鉴定山珍海味的干货制品是新鲜的动、植物的原料经脱水加工的干制品。干货原料脱水干制，易于储存保管，便于运输，打破了季节、产地的界限，延长了使用时间，扩大了供应范围，在烹调中占有很重要的位置。因此，进行干货原料的检验，鉴别其品质的优劣，对烹...     

爬山玉的鉴定

<正> 从去年下半年开始,福州翡翠市场上出现了越来越多的新种玉——爬山玉手镯,其特征是:水头好,玻璃光泽,表面光亮,翠性明显,飘灰兰花,敲击声发闷,多玉纹,较易碎。由于水头好,飘灰兰花,看上去似在清澈的河里绿色的鱼草在飘荡,有情有景,很实在,除色不够绿外,还是相当美丽的,且价格在千元以下,很适合工薪阶层佩戴。     

The fracture of jade

Fracture parameters have been measured in jade samples obtained from three sources. Fracture toughness values lie between 2.9 and 5.5 MN m^–3/2, whereas fracture energies are between 269 and 986 J m^–2. The high resistance of jade to crack propagation is related to its fibrous microstructure. In materials from each source, the diameter of individual nephrite fibres was 1/2 m, but fibres tend to be grouped in feather like or cylindrical bundles, with the bundles arranged randomly in a woven type structure. Sub-critical crack growth can occur in jade in the presence of water but not in lapping oil. The fracture behaviour of jade is compared with that of common rocks and engineering ceramics.     

中国古玉器(商-汉)的鉴定方法

对中国古玉器(商-汉)的鉴定方法进行研究。一般以肉眼和10倍放大镜,主要依据纹饰、质地、雕工等特征对古玉进行无损鉴定。利用综合资料去分析和断定古玉的年代。     

中国古玉器(商-汉)的分类及特征

通过对商代、西-东周、春秋、战国以及汉代古玉器的研究分析以及分类汇总,归纳总结了商-汉不同时期古玉器的不同特征。此研究结果对古玉器及仿制品的鉴别具有重要的意义。     

Strength and toughness of jade and related natural fibrous materials

Room temperature mechanical properties measured for natural fibrous jade materials with random fibre orientations were similar to strengths (e.g. 100 MPa) and toughnesses,K _IC, (e.g. 3M Pa m^1/2) in other studies. However, nearly three- and five-fold higher values were found respectively for strength and fracture toughness of jade with highly aligned fibres for crack propagation perpendicular to the fibres. Further, the results indicate significantly higher strength and toughness with decreasing fibre diameter and increasing aspect ratio, and an accompanying increase in intrafibre fracture. However, failure was predominantly catastrophic in character for all fibre orientations, indicating some material (i.e. matrix) is necessary for non-catastrophic failure as found in fibre composites.     

Structural irregularities in nephrite jade: An electron microscope study

The jade mineral nephrite has been examined by electron diffraction and high resolution lattice imaging. Planar defects parallel to (010) were observed. It is shown that these are Wadsley defects, consisting of multiple-chain lamellae in place of the double-chain amphibole host structure. Examples of three- and six-fold chain defects are shown.     

Embrittlement of ancient silver

Ancient silver may become brittle and damaged owing to long-term corrosion and changes in the microstructure. Recognition and determination of corrosion-induced and microstructurally-induced embrittlement, and also their synergy, are important for restoration and conservation of ancient and historic silver. The types of embrittlement are described and illustrated, using examples of ancient and historic silver artefacts, including the famous Gundestrup Cauldron, a masterpiece of European Iron Age silverwork. In particular, the use of automated Electron BackScatter Diffraction (EBSD) enables improved analysis and assessment of corrosion-induced embrittlement. The knowledge obtained from detailed investigations is helpful not only in determining the best ways to restore and conserve embrittled silver objects, but also in defining the possible extent of the embrittlement problem. This is illustrated by a straightforward statistical analysis.     

The alkenone-CO2 proxy and ancient atmospheric carbon dioxide

Cenozoic climates have varied across a variety of time-scales, including slow, unidirectional change over tens of millions of years, as well as severe, geologically abrupt shifts in Earth's climatic state. Establishing the history of atmospheric carbon dioxide is critical in prioritizing the factors responsible for past climatic events, and integral in positioning future climate change within a geological context. One approach in this pursuit uses the stable carbon isotopic composition of marine organic molecules known as alkenones. The following report represents a summary of the factors affecting alkenone carbon isotopic compositions, the underlying assumptions and accuracy of short- and long-term CO(2) records established from these sedimentary molecules, and their implications for the controls on the evolution of Cenozoic climates.     

寿山石鉴定

寿山石是产于福州寿山乡的国石候选石,经查文献中有关寿山石鉴定文章不多。本文就寿山石鉴定特征及与相似玉石区别进行论述,并详细描述寿山石三大品种田坑石、山坑石、水坑石特点,以飨读者。     

田黄石鉴别

田黄石有“石中之王”的美称,本文针对田黄石品种、分类、以及鉴定特征及相似石种区别进行论述,以飨读者。     

Mechanical behaviour of ancient masonry

The aim of this research was to build a behaviour law for ancient masonry made during the nineteenth century with bricks and lime mortar bonds. This work should be of interest to researchers involved in the study of ancient masonry structures like arch bridges built in this period. To assess the masonry capacity vaults to support service loads and to determine their collapse loads, engineers need mechanical behaviour laws for their component parts. This experimental research was performed to explore the behaviour of the bricks, of the lime mortar, and of a wall until their failure in compression. In parallel the bricks / mortar interface criterion failure under shear and tensile load is characterised. After laboratory tests, numerical simulations were carried out using a finite element method (FEM) to define an homogenised behaviour law for a macro element including bricks and lime mortar bonds. In this goal, a behaviour law was firstly found for each component and then for the masonry as a whole by a FEM homogenisation process, including the non-linear behaviour domain up to the compression failure. The tension failure being reported into an interface element for which the failure criterion was adjusted on specific tests.