LCAS SiC_w ZrO_2复合材料的力学性能及其微观结构

研究了ＬＣＡＳＳｉＣｗＺｒＯ２ 复合材料的力学性能及其微观结构．力学性能分析表明：ＳｉＣｗ 增韧和ＺｒＯ２ 相变增韧的加和性不是简单地叠加,ＳｉＣｗ 增韧提高了ＺｒＯ２ 相变增韧效果．体积分数分别为５５ ％ ,３０％ ,１５％ 的ＬＣＡＳ,ＳｉＣｗ ,ＺｒＯ２ 复合材料的断裂韧性Ｋ１Ｃ和抗弯强度σｂ 达到６－４ ＭＰａ·ｍ１／２ 和３３１－７ ＭＰａ．透射电镜（ＴＥＭ） 图象表明：复合材料中ＺｒＯ２ 起了应力诱导相变增韧作用;ＬＣＡＳ／ＳｉＣｗ 界面较清晰,其宽度约１５ ｎｍ ;搭在ＬＣＡＳ／ＳｉＣｗ 界面两侧的杆状ＴｉＣ 颗粒增加了界面结合强度     

SiC晶须对Al2O3／TiN／ZrO2复合材料组织与性能的影响

研究了在ＺｒＯ２含量在１５ｗｔ％晶须含量对Ａｌ２Ｏ３／ＴｉＮ／ＺｒＯ２／ＳｉＣｗ复合材料的显微结构与力学性能的影响。当ＳｉＣｗ含量由１０ｗｔ％增加到３０ｗｔ％时，弯曲强度σｆ和断裂韧性ＫＩＣ最高可达１１３４ＭＰａ和１２．２６ＭＰａ．ｍ＾１／２。用ＳＥＭ，ＴＥＭ观察分析了复合材料的表面抛光组织，断口形貌和微观结构。试验结果表明，复合材料强韧化机制主要为晶拔拔出，相变增韧，裂纹偏转和晶须与基体界面解高     

ZrO_2增韧Al_2O_3／SiCw陶瓷复合材料研究

研究了热压烧结Ａｌ２Ｏ３＋０．２０ＳｉＣｗ（体积分数，下同）－ＺｒＯ２（摩尔分数为０．０２Ｙ２Ｏ３，记为ＺｒＯ２（０．０２Ｙ））陶瓷复合材料的力学性能及韧化机制。结果表明，在Ａｌ２Ｏ３＋０．２０ＳｉＣｗ陶瓷中添加ＺｒＯ２（０．０２Ｙ）颗粒可使Ａｌ２Ｏ３＋０．２０ＳｉＣｗ材料进一步韧化和强化；室温下Ａｌ２Ｏ３＋０．２０ＳｉＣｗ＋０．３０ＺｒＯ２（０．０２Ｙ）复合材料的断裂韧性和抗弯强度分别可达１０．８５ＭＰａ·ｍ１／２和１２０７ＭＰａ。断口形貌和裂纹扩展途径的ＳＥＭ观察和ＸＲＤ分析结果表明，复合材料的增韧机制为裂纹偏转与绕过，晶须桥接与拔出以及相变增韧，并且晶须增韧与相变增韧具有良好的叠加性     

SiC晶须补强ZTA（Y）陶瓷基复合材料的研究

本文将高强、高模量的ＳｉＣ晶须引入以Ｙ２Ｏ３稳定的ＺｒＯ２（ｔ）相变增韧Ａｌ２Ｏ３基陶瓷材料［即ＺＴＡ（Ｙ）］中．研究了不同晶须含量对复合材料的抗弯强度和断裂韧性的影响．实验结果表明，ＳｉＣ晶须能明显提高ＺＴＡ（Ｙ）陶瓷基复合材料的强度和韧性，体积含量为２０％的ＳｉＣ晶须的复合材料性能可达：σｂｂ＝８３０ＭＰａ，Ｋｉｃ＝９．８ＭＰａｍ１／２．通过与ＳｉＣｗ／Ａｌ２Ｏ３复合材料系统的比较分析，认为ＳｉＣｗ／ＺＴＡ（Ｙ）复合材料中，由于热膨胀系数差异所产生的基体中的张应力可由诱导ＺｒＯ２（ｔ）的马氏体相变来缓解，其中存在着相变增韧和晶顺补强的双重强韧化机制     

碳化硅、氧化锆增韧氧化铝复相陶瓷的研究

在纳米氧铝粉中加入碳化硅晶须和纳米氧化铝粉，通过烧结得到细晶的氧化铝基复相陶瓷，达到了提高氧化铝陶瓷断裂韧性的目的．研究了Ｎａｎｏ－Ａｌ２Ｏ３／ＳｉＣ（ｗ）、ＺｒＯ２复相陶瓷的烧结温度、晶粒尺寸、ＳｉＣ（ｗ）含量等对细晶Ａｌ２Ｏ３基复相陶瓷材料断裂韧性的影响．采用纳米Ａｌ２Ｏ３粉，可使烧结温度大幅度下降，在１６００℃即可得到致密的细晶陶瓷材料．ＳｉＣ（ｗ）质量分数ｗ为１８％时可以得到较高的断裂韧性值，ＫＩＣ＝６．９６ＭＰａ·ｍ１／２．晶须增韧的机理仍然是晶须的拔出和断裂．加入ＺｒＯ２后，利用ＺｒＯ２的相变增韧的效果，可以使Ａｌ２Ｏ３基陶瓷材料的断裂韧性进一步提高．     

热压烧结制备晶须补强复合材料

通过热压烧结成功地制备了高致密度的ＳｉＣｗ晶须补强ＣＭＡＳ玻璃陶瓷基复合材料．ＳｉＣｗ晶须经超声波分散以后,加入到已球磨好的ＣＭＡＳ粉末与有机添加剂的浆料中,搅拌得到ＳｉＣｗ分散均匀的混合浆料．含有机添加剂的浆料在较低的压力下（２．３７ｋＰａ）挤压通过微孔（＝２５０μｍ）,获得ＳｉＣｗ晶须分散均匀并高度取向的纤维状生坯．含晶须２０％的ＣＭＡＳ通过无压烧结,烧结后样品相对密度仅达８０％．但是通过热压烧结就可制备出相对密度达９４．２％的复合材料．     

Y－TZP和氮气压力对GPSSi_3N_4性能的影响

本文研究了Ｙ－ＴＺＰ（３ｍｏｌ％Ｙ２Ｏ３）和氮气压力对ＧＰＳＳｉ３Ｎ４陶瓷材料的烧结性能和力学性能、相组成及微观结构的影响，添加５ｗｔ％、１０ｗｔ％、１５ｗｔ％、２０ｗｔ％Ｙ－ＴＺＰ的氨化硅复合材料在１７７０～１８００℃，氮气压力分别为１ＭＰａ、２ＭＰａ、３ＭＰａ下烧成，获得相对密度＞９５％的烧结体。实验结果表明：添加＜１０ｗｔ％的Ｙ－ＴＺＰ及增大氮气压力有利于改善氰化硅陶瓷材料的烧结性能；Ｙ－ＴＺＰ可提高Ｓｉ３Ｎ４基体的断裂韧性，添加１５ｗｔ％ＴＺＰ的Ｓｉ３Ｎ４材料断裂韧性可达８．３３ＭＰａｍ１／２，与基体相比提高３０％，微裂纹增韧和第二相粒子增韧为主要增韧机理．     

SiC_p－Si_3N_4基复合材料及其力学性能

研究了ＳｉＣ片晶（ＳｉＣｐ）强化Ｓｉ３Ｎ４基复合材料及其力学性能和增韧机理。研究结果表明，加入ＳｉＣｐ使Ｓｉ３Ｎ４材料的强度明显提高，并在ＳｉＣｐ含量（ＳｉＣｐ）＝０．２０（ＳｉＣｐ的体积分数）时有一峰值，ＳｉＣｐ加入量进一步增加使强度有较大降低。ＳＥＭ观察表明，裂纹偏转、片晶桥接是主要增韧机理，片晶拔出、基体细化等亦对断裂韧性的增加作出贡献，其作用与晶须增韧的机理相似。     

Si_3N_4-SiC纳米复合陶瓷材料的研究

用粒度为 ５０～７０ ｎｍ的纳米级 ＳｉＣ粉体与微米级的 Ｓｉ３Ｎ４粉体复合来制备 Ｓｉ３Ｎ４－ＳｉＣ纳米复合陶瓷材料，对纳米ＳｉＣ含量不同的Ｓｉ３Ｎ４－ＳｉＣ纳米复合陶瓷材料的微观组织结构与性能的关系进行了研究。结果表明：纳米ＳｉＣ质量分数为１０％时，经热压烧结法制备的Ｓｉ３Ｎ４－ＳｉＣ纳米复合陶瓷材料的抗弯强度为 ８４４ ＭＰａ，断裂韧性为 ９． ７ ＭＰａ· ｍ１／２。微观组织结构的研究还表明，纳米ＳｉＣ的不同含量影响着基体Ｓｉ３Ｎ４的晶粒形貌，从而决定了复合材料的性能。探讨了纳米级ＳｉＣ在基体中的形态、分布及其对基体强化增韧的新机制。     

SiC长纤维增强玻璃陶瓷基复合材料的研究

采用涨浆浸渍热压工艺制备ＫＤ－１ＳｉＣ长纤维增强玻璃陶瓷其复合材料。研究烧结温度和纤维体积分数对复合材料力学的影响。ＳｉＣｆ／ＢＡＳ复合材料的抗弯强度和断裂韧性最大达到４９４．１ＭＰａ和１８．２８ＭＰａ．ｍ＾１／２,ＳｉＣｆ／ＭＡＳ复合材料的抗弯强度和断裂韧性最大达到５３８．７ＭＰａ和１６．７０ＭＰａ．ｍ＾１／２。结合试样的断口形貌和抗载荷－位移曲线分析了复合材料的失效方式。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-