轻质化MA/ODS镍基高温合金高温氧化行为

采用机械合金化(MA)和真空烧结工艺制备了Y2O3质量分数为2%～20%的氧化物弥散强化(ODS)镍基高温合金,在1 000℃空气中对合金试样进行100h的静态氧化实验,研究了Y2O3含量对合金高温氧化性能的影响与作用机制.结果表明:适量稀土氧化物Y2O3的加入(质量分数≤5%)可促进完整Cr2O3氧化膜的形成,提高氧化膜与合金基体的附着力,改善氧化膜的抗剥落性,减缓合金在1 000℃的氧化速度,从而有效提高合金的抗高温氧化性能.但过量添加则会使其抗氧化性能迅速下降.     

高碳、高合金铁基渗铜烧结阀座材料

研究了基体中不同合金元素及热处理对高碳、高合金铁基渗铜烧结阀座材料的密度和力学性能的影响。结果表明，用机械混合高碳、高合金粉末压坯经过一步法烧结／熔渗后，密度达到７．８８ｇ／ｃｍ＾３（相对密度９８．２％），硬度和抗弯强度分别达到ＨＲｃ４５．４和１１２４ＭＰａ。将渗铜后的材料在９００℃淬火，５８０℃高温回火后，铁颗粒中组织主要为回火马氏体，材料硬度达到ＨＲｃ４０以上。     

Ni-Cr-W 基高温合金高温氧化行为研究

研究了一种Ni-Cr-W基高温合金在700～1 200℃的高温氧化行为。采用XRD,SEM/EDS,拉曼光谱和维氏硬度等表征手段对氧化膜中物相、微区成分分布及合金表面硬度等结构及性能进行了研究。结果表明：随着氧化温度增加,合金中的Ni和Cr最先被氧化形成Cr₂O₃和NiO,其中的Cr₂O₃是致密的氧化层;当温度高于1 050℃时,有少量的SiO₂生成;实验范围内合金的氧化动力学曲线符合指数增长规律,氧化增重量都小于1 mg/cm²,说明合金是抗氧化级;合金在1 200℃下循环氧化后,氧化层厚度和增厚量都明显增加,其抗氧化性能明显变差;在1 100℃下氧化后合金的维氏硬度基本不变,而经过1 200℃循环氧化后氧化层会出现起皮剥落,导致合金表面硬度下降。     

碳钢膏剂渗硅

本文描述了碳钢膏剂渗硅的工艺和理论。介绍了用金相、显微硬度,电子探针分析和X-射线结构分析等方法,测定渗硅层的组织结构及控制显微组织的工艺。在渗硅剂(组成:35—65%硅源粉、5%卤化物、30%防烧结剂)中加入比例大的卤化物,于1100—1180℃时对碳钢进行10—60分钟的膏剂渗硅,可得含硅量约为17.7%(重量)、厚度达0.18—1.2mm的渗层,其渗硅效率比气体法提高约一倍。氧化和腐蚀试验表明:渗硅层在750℃以下能有效地防止循环氧化;在40℃时能耐20%Ⅱ_?SO_4的腐蚀。此法操作简便,易于局部涂渗,渗层表面质量好。     

钙在镁合金熔炼中的阻燃机理

熔炼了钙的质量分数为0.5%~5.0%,铝的质量分数为9.0%的10种镁合金,研究了Ca的加入对合金阻燃效果的影响.分别取定量的10种合金在700℃的高温下进行氧化增重的测量,并对合金表面的氧化形貌进行了观察.实验结果表明:镁合金加入钙后,其表面在高温下生成了CaO及少量MgO的复合致密氧化膜,这层氧化膜隔绝了空气,阻止了镁的燃烧;当钙的质量分数为3.5%时,可起到良好的阻燃效果.     

4004 铝合金表面恒温氧化动力学研究

模拟４００４／３００３／４００４热轧复合工艺,对４００４合金在３５０～５２５℃分别加热保温所制备的试样表面氧化情况、氧化层厚度进行了宏观分析．用电子能谱仪（ＸＰＳ）对４００４合金４７５℃下各保温时间的试样表面氧化层进行Ａｒ＋逐层溅射剥离,对剥离面进行ＸＰＳ分析．对ＸＰＳ图谱进行了计算,结果表明：４００４合金在４７５℃×３ｈ试样表面已呈深灰色,氧化已较严重;在４７５℃恒温下,４００４合金保温１～２ｈ表面氧化层增厚遵循对数曲线变化;在２～６ｈ内,表面氧化层按一定比例增长,超过６ｈ后,表面氧化层增厚有所减缓．适当降低热轧复合时的加热温度,控制４００４铝合金表面氧化层的厚度,能提高复合成功率．     

ASP2030气体渗铬层的制备及性能

研究采用热反应扩散镀膜法(Thermal Reactive Diffusion/Deposition,TRD)在ASP2030粉末高速钢上表面进行气体渗铬处理,在相同的时间下对有无氮化预处理的试片进行950℃、900℃、850℃、800℃、750℃的渗铬实验,再用扫描电镜(SEM)线扫描分析(line-scan),测量铬原子扩散深度,并求出有无氮化预处理渗铬的扩散激活能(Q)及扩散常数(D0),讨论彼此间差异的因子。再将预氮化渗铬及渗铬后的试片,用耐磨试验机进行不同渗铬温度下渗铬层的磨耗情形,了解渗铬层的耐磨性,最后再以X光绕射分析,测量有无氮化处理基材表层渗铬层中晶体的组成,探讨在高温及低温下晶体的变化情况。实验结果显示,在950℃、900℃、850℃、800℃及750℃渗铬中,经氮化处理后ASP2030铬原子扩散深度增加。将所量测各条件渗铬后膜厚以最小平方法求出ASP2030有无氮化渗铬的线性方程式,可得到ASP2030渗铬和ASP2030预氮化后渗铬扩散激活能分别为118.965kJ/mol及111.632kJ/mol,表示氮化对ASP2030激活能的影响较小。ASP2030有无氮化预处理的表层硬度为1 570 Hv及1 860 Hv。在耐磨实验中,ASP2030粉末钢渗铬后的渗铬层耐磨性差。在XRD绕射分析所显现的晶体构造与无氮化高温渗铬时,两者基材均有Cr_2C的组织,有氮化预处理时则另有Cr_2N的结构,在较低温渗铬时,基材在无氮化处理时是Cr_7C_3,则氮化处理后有CrN的结构。     

ODS-310合金的高温氧化行为

采用静态氧化增重实验及扫描电镜、能谱分析和X射线衍射分析等手段,研究了ODS-310合金在高温环境下的氧化行为,分析了氧化层的形貌、成分和物相,并对其高温氧化动力学曲线进行拟合.实验发现各个温度下的氧化动力学曲线均基本符合抛物线规律.在700℃和900℃氧化100 h以后,ODS-310合金均表现出优异的抗氧化性能.但是,当氧化温度为1100℃时,氧化层厚度明显增厚,而且氧化层有疏松和不连续的现象,不利于氧化层对基体的保护.氧化程度随着氧化温度的提高和氧化时间的延长而加剧.通过能谱和X射线衍射综合分析可知氧化层的物相为Cr₂O₃.     

FGH95合金的高温氧化行为

通过静态增重实验、X射线物相分析、扫描电镜形貌观察及微区成分分析等手段,系统研究了FGH95合金在不同温度下的高温氧化行为及高温氧化动力学规律.结果表明:FGH95合金在800～1 000 ℃具有较好的抗氧化性能,其氧化动力学曲线基本符合抛物线规律;在1 100 ℃,氧化较为严重,其氧化动力学曲线由两段抛物线组成.氧化层主要由Cr2O3和TiO2组成,在1 100 ℃高温氧化后有少量的NiCr2O4生成.     

Fe-0.48%V及Fe-1.69%V合金碳化物析出型渗碳(CD)

研究了Fe048%V及Fe169%V合金的CD渗碳,用金相显微镜及扫描电子显微镜分析了渗层的组织形貌,对表层进行了X射线衍射分析,确定了以上两种合金在950℃渗碳的最佳碳势为140%C,此碳势是渗层不出现Fe3C组织的最高碳势,渗层组织为马氏体基体上分布弥散细小的等轴碳化物V4C3,平均尺寸为250nm·渗层最高硬度均超过了HM1000,Fe048%V合金的硬化层厚度为1600μm,Fe169%V合金的硬化层厚度为1000μm,两种合金都具有极高的耐磨性,Fe169%V合金的耐磨性超过了淬火加回火的...     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

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-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that