陶瓷刀具的发展与使用

陶瓷刀具有以下性能特点 :(1 )有很高的硬度和耐磨性 ;(2 )有很高的高温性能 ;(3 )有良好的抗粘结性能 ;(4 )化学稳定性好 ;(5 )磨擦系数较低 ;(6)脆性大 ,强度低 ;(7)导热性能差 ;陶瓷刀具的使用应注意以下问题 :(1 )不同材基的陶瓷刀具适用不同被加工材料 ;(2 )掌握陶瓷刀具适用的加工工艺 ;(3 )掌握使用陶瓷刀具对机床设备的要求。     

刀具材料的研究现状及展望

随着难加工材料的日益增多以及对加工效率的要求的提高,刀具的发展对提高生产效率和加工质量具有直接影响。本文以刀具材料为主线,介绍了高速钢、硬质合金、陶瓷、超硬材料等刀具材料的性能以及现状。根据刀具材料的优缺点提出其适合的加工切削条件,同时在理论层面提出对未来发展的思考。     

纳米复相陶瓷刀具性能研究

纳米复相陶瓷刀具材料的研究成功有望从根本上解决陶瓷材料的脆性问题,比起传统陶瓷刀具材料,它具有更高的抗弯强度、断裂韧性等力学性能。本文介绍纳米复相陶瓷的增韧补强机理;对研制高性能纳米陶瓷刀具材料需考虑的主要因素进行了探讨。     

陶瓷刀具的发展与使用

陶瓷刀具有以下性能特点：（1）有很高的硬度和耐磨性；（2）有很高的高温性能；（3）有良好的抗粘结性能；（4）化学稳定性好；（5）磨擦系数较低；（6）脆性大，强度低；（7）导热性能差；陶瓷刀具的使用应注意以下问题；（1）不同材基的陶瓷刀具适用不同被加工材料；（2）掌握陶瓷刀具适用的加工工艺；（3）掌握使用陶瓷刀具对机床设备的要求。     

Al2O3/TiCN陶瓷刀具材料的抗热震性能及断裂机理研究

用传统的淬火法对Al2 O3 TiCN陶瓷刀具材料的抗热震性能进行了详细的研究 ,发现该种陶瓷刀具材料的临界热震温差为 32 0℃ ;当温差超过 32 0℃时 ,强度有明显的下降。通过对热震后试样表面的显微观察发现 ,试样表面出现横向裂纹。理论分析表明第一类和第二类热应力的共同作用是材料热震开裂的原因     

A12O3／TiCN陶瓷刀具材料的抗热震性能及断裂机理研究

用传统的淬火法对A12O3／TiCN陶瓷刀具材料的抗热震性能进行了详细的研究，发现该种陶瓷刀具材料的临界热震温差为320℃；当温差超过320℃时，强度有明显的下降。通过对热震后试样表面的显微观察发现，试样表面出现横向裂纹。理论分析表明第一类和第二类热应力的共同作用是材料热震开裂的原因。     

多相复合陶瓷刀具材料热压过程的计算机模拟与工艺设计Ⅰ——温度场模拟与工艺设计

建立了陶瓷刀具材料热压过程的传热模型,并以Al2O3／SiC／(W,Ti)C多相复合陶瓷刀具材料为例,通过采用计算机模拟技术对坯体温度场的研究,进行了相应的热压工艺设计．结果表明：升降温速率的大小及烧结前气孔的存在对坯体内温度场影响较大．综合考虑材料性能和制各效率的要求,在本试验条件下,升温速率以0．5～0．75℃／s而降温速率以0．33℃／s为宜．从温度场的角度来看,在陶瓷刀具材料热压成型之前,应先冷压成坯,以提高坯体的初始相对密度,降低热压过程中的温差,改善材料的物理力学性能。     

原位合成碳化钛晶须增韧氧化铝陶瓷刀具材料前驱体组分研究

本文对采用碳热还原法制备原位合成TiC晶须增韧氧化铝基陶瓷刀具材料的工艺中,Ni和NaCl含量对晶须生长状态和刀具材料力学性能的影响及其机理进行了探讨。结果表明,当前驱体中Ni和NaCl的含量为TiO2：Ni：NaCl（摩尔比）=1：0.05：0.5时,能够获得产量较高、长径比较理想的TiC晶须,从而有利于提高刀具材料的力学性能;提高Ni含量和NaCl含量则会导致晶须长径比减小和产量降低,不利于提高刀具材料的力学性能。     

陶瓷刀具及其应用技术

陶瓷刀具是具有优良切削性能的新型刀具,近些年得到迅速发展并且有广阔应用前景。主要有氧化铝（Ａｌ２Ｏ３）基、氮化硅（Ｓｉ３Ｎ４）基、碳化钛（ＴｉＣ）基陶瓷、复合陶瓷以及碳化硅晶须增韧陶瓷。本文对陶瓷刀具的种类、性能及具体使用条件进行了全面综述。     

可加工陶瓷材料ZrO2/CePO4钻削刀具的磨损

通过ZrO2/CePO4陶瓷的钻削实验,研究刀具磨损特性,分析各因素对刀具磨损的影响.分别应用硬质合金和高速钢钻头对制备的可加工陶瓷ZrO2/CePO4进行钻削加工.通过主后刀面的磨损测试和电镜观察,考察ZrO2/CePO4钻削中的刀具磨损形态、过程以及刀具材料、刀具角度、冷却条件对刀具磨损的影响.结果表明,高速钢刀具因磨损严重,不适于ZrO2/CePO4陶瓷的钻削.可加工陶瓷ZrO2/CePO4钻削过程中,硬质合金钻头的磨损主要包括3种形态:主后刀面磨损、第一副后刀面磨损和横刃磨损.与低碳钢比较,钻削ZrO2/CePO4陶瓷时硬质合金刀具的磨损速度增长较快,冷却条件对刀具磨损的影响显著.刀具材料和冷却条件是影响ZrO2/CePO4陶瓷钻削刀具磨损的主要因素.     

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-