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1.
以聚丙烯(PP)为基材与高介电常数的BaTiO3复合而成的BaTiO3/PP复合膜是一种电性能优异的高频、交频电介质绝缘材料,它具有介质损耗小、介电常数不随频率而变化、防潮性能优良及价廉等优点.通过BaTiO3/PP复合膜的试制,研究了填料BaTiO3的表面处理,含量及介电常数等因素与BaTiO3/PP复合膜电性能间的关系.  相似文献   

2.
采用X射线衍射、扫描电镜和差热分析等手段,研究了钙磷化合物-镁铝尖晶石(CP-Spinel)复合生物材料的微观结构、力学性能和生物学特性。结果表明,Spinel的加入显著地提高CP材料的力学性能,在高温下它还阻止磷酸钙发生相转变,从而保证了该材料的生物活性及适合于人体骨需求的力学性能.CP-Spinel材料具有很好的生物相容性,无毒无刺激性,溶血指数小于2%。  相似文献   

3.
SBR—包覆剂—UFCaCO3体系的粒径分布与力学性能   总被引:6,自引:0,他引:6  
用高分子树脂为包覆剂,以凝聚共沉法制备了超细碳酸钙(UFCaCO3)填充型粉末SBR,研究了产物粒径及其硫化胶力学性能的影响因素,结果发现,当包覆剂大分子的极性单体单元含量约等于7%及Tg大于等于38度,可获得粒径小于等于0.9mm的产物达99.5%以上;当包覆剂的Tg为38-45度,UFCaCO3表面改性剂用量为1-4质量份及UFCaCO3填充量为100质量份,产物硫化胶的力学性能最佳,改性UFCaCO3填充量在75-200质量份的广阔范围内,其硫化胶保持良好的力学性能,并显著优于块状SBR/UFCaCO3由机械混炼所得硫化胶的力学性能,扫描电镜分析显示,UFCaCO3在橡胶基体中有良好的分散性。  相似文献   

4.
研究了Al2O3-TiB2复合陶瓷的力学性能.结果表明,当TiB2含量为20wt%时,能获得较高的综合性能.用此配方制成的陶瓷刀具具有较高的耐磨性能.后刀面磨损量VBmax比YW1低1倍左右.陶瓷刀具的磨损以微区剥离为主要机制.此外,还对比了陶瓷刀具和硬质合金刀具的切削力变化情况.  相似文献   

5.
本文设计了反应与分离合二为一的膜催化反应器,将自制的负载型TiO2-聚丙烯疏水性复合膜材料用于以Ni-Cu/MSO为催化剂的CO+H2合成乙烯的反应,考察了反应中CO的转化率和乙烯的选择性。实验结果表明:以Ni-Cu/MSO为催化剂CO+H2合成乙烯膜催化反应(反应温度为150℃),与常规的催化反应在同温度下进行比较,CO转化率提高了8.5%,C2H4的选择性提高了12%.  相似文献   

6.
利用废旧纤维、传统纺织和热压设备,研究了废旧聚酯/聚丙烯纤维复合板材的成型工艺,探讨了成型温度、时间、压力等工艺参数和聚丙烯纤维质量分数对复合板材力学性能的影响。得出废旧纤维板材最佳成型条件为:聚丙烯纤维质量分数为40%、成型温度200℃、成型时间4min、成型压力10MPa,此时制备的纤维复合板材力学性能最佳,其拉伸强度为51MPa,弯曲强度为65.4MPa。  相似文献   

7.
Mg-Al基合金加铋合金化对其力学性能的改善作用   总被引:4,自引:0,他引:4  
研究了合金元素Bi对Mg-9Al-0.8Zn(AZ91)基合金显微组织和力学性能的影响,结果表明Bi质量分数超过0.5%时,基体中有富Bi的第二相颗粒形成,并随着Bi加入量的增多而增加,该颗粒相具有六方D52结构,热稳定性较高,适量Bi的加入改善了合金的铸态组织,提高了合金的室温和高温强度,改善了抗蠕变性能,而塑性有所降低。  相似文献   

8.
研究了加入DL-411-DF偶联剂及EVA改性剂后,PP-粉煤灰玻璃微珠(简称微珠)复合体系的力学性能的变化通过扫描电镜及力学性能分析测试,结果表明,使用DL-411-DF偶联剂对微珠有良好润湿包覆作用,增加了微珠和PP之间的亲和力EVA和DL-411-DF共用在微珠-PP体系,使抗缺口冲击性能得到提高,具有较大的实用价值  相似文献   

9.
山梨醇和有机磷类成核剂对聚丙烯性能和结晶行为的影响   总被引:2,自引:0,他引:2  
研究了有机磷类成核剂Irgastab NA—11和ADKNA-21以及山梨醇衍生物类成核剂Irgaelear DM和MiUad3988对聚丙烯性能和结晶行为的影响.研究结果表明,有机磷类成核剂对聚丙烯力学性能的改善效果要优于山梨醇类成核剂,而后者对聚丙烯透明性能的改善效果要优于有机磷类成核剂.同时,有机磷和山梨醇类成核剂对聚丙烯结晶峰温度的影响相类似.当成核剂的浓度为0.2wt%时,与空白聚丙烯相比,IrgastabNA—11和ADKNA-21成核聚丙烯拉伸强度和弯曲模量分别提高19.35%,17.67%和29.48%,24.84%,雾度分别降低43.58%和44.01%;而Irgaclear DM和Millad 3988成核聚丙烯的拉伸强度和弯曲模量分别提高7.03%,7.46%和7.20%,11.96%,雾度分别降低51.03%和52.23%.此外,微观形态研究表明,有机磷和山梨醇类成核剂的加入都可以显著降低聚丙烯的球晶尺寸.  相似文献   

10.
采用标准电子陶瓷工艺,制备了Ba0.6Sr0.4TiO3/MgO/Mg2SiO4复相陶瓷(MgO和Mg2SiO4按相同重量加入),研究了MgO和Mg2SiO4含量对复相陶瓷微观结构、介电性能及介电可调性的影响.结果表明,随着MgO和Mg2SiO4含量的增加,陶瓷的晶粒尺寸略有增大,低频(100kHz)介电常数、介电损耗、介电可调度和介电常数温度系数降低.随着偏置电场的增强,介电常数降低,介电损耗变化不大(均在10^-3量级).当MaO和Mg2SiO4的百分含量均为30%时,获得了室温介电常数为101.6、介电损耗为0.0017及1.79kV/mm偏置电场下介电可调度为12.19%、介电常数温度系数为0.009℃^-1的介电性能。  相似文献   

11.
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.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
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.  相似文献   

13.
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.  相似文献   

14.
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。  相似文献   

15.
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.  相似文献   

16.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

17.
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.  相似文献   

18.
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.  相似文献   

19.
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-  相似文献   

20.
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-  相似文献   

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