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1.
LaCrO3—NiMn2O4复合陶瓷的结构分析   总被引:5,自引:1,他引:5  
刘树英  杨文 《硅酸盐学报》1995,23(2):170-174
将尖晶石型NiMn2O4及钙钛矿型LaCrO3这二者电阻率较高的半导体陶瓷热敏材料复合并经高温烧结后,其复合体电阻率大幅度降低。应用XRD,XPS,TEM和SEM对复合体结构进行较为系统的研究,结果表明:NiMn2O4与LaCrO3按一定比例复合后,在烧结过程中两者之间有离子迁移发生,离子迁移的结果使钙钛矿结构的LaCrO3转变为高导电相的La[Cr1-x-yNixMny]O3(0〈x〈1,0〈y  相似文献   

2.
将尖晶石型NiMn_2O_4及钙钛矿型LaCrC_3这二者电阻个较高的半导体陶瓷热敏材料复合并经高温烧结后,其复合体电阻率大幅度降低。应用XRD,XPS,TEM和SEM对复合体结构进行较为系统的研究,结果表明:NiMn_2O_4与LaCrO_3按一定比例复合后,在烧结过程中两者之间有离子迁移发生,离子迁移的结果使钙钛矿结构的LaCrO_3转变为高导电相的La[Cr_(1-x-y)Ni_xMN_y]O_3(0<y<0,0<x+y<0),它使复合体电阻率大幅度降低。  相似文献   

3.
Ba^2+改性PFN—PFW系统反应机理的研究   总被引:1,自引:0,他引:1  
研究了Ba^2+改性PFN-PFW系统的反应机理。对该系统中钙钛矿结构的生成机理进行了研究,XRD分析结果证明,系统除生成复合钙钛矿相之外,还生成B位缺陷菱型焦氯石相Pb22Nb18O67和极少量的A位缺陷四方焦氯石相Pb3Nb4O13,前一种焦氯石相易于向钙钛矿相转化;后一种焦氯石相始终存在,不易转化成钙钛矿相。系统没有发现理想焦氯石相Pb2Nb2O7结构。  相似文献   

4.
李懋强 《硅酸盐学报》1996,24(5):504-508
本文讨论了复合钙钛矿型Ba(Mg1/3Ta2/3)O3中B位离子的有序程序同材料的介电损耗之间的关系。用X射线谱和Raman光谱研究了陶瓷烧结温度对Ba(Mg1/3Ta2/3)O3中B位离子的有序程度的影响,当适当提高烧结温度可增大有序程度。  相似文献   

5.
化学法制取RE—Ni—B—Al2O3复合镀层及其性能研究   总被引:3,自引:0,他引:3  
提出RE-Ni-B-Al2O3化学复合镀溶液和工艺条件,以获得B4.8wt%、RE0.45wt%、Al2O36.2wt%的复合镀层。分析镀液中RE(稀土)、Al2O3浓度、搅拌速度、温度对镀速、复合镀层Al2O3共析量、硬度和耐磨性的影响,使用X射线衍射仪和扫描电镜观察镀层微观形貌。稀土的加入可以提高晶化温度和镀层性能。在热处理中复合镀层晶变过程为非晶态-混晶态-晶态,在350℃、500℃热处理1  相似文献   

6.
AlN—BN复合陶瓷的介电性能   总被引:9,自引:2,他引:9  
杜帅  李龙土 《硅酸盐学报》1997,25(4):433-439
以AlN-BN复合陶瓷为研究对象,着重探讨了AlN-BN复合陶瓷的极化机理,应用基本的介电介质物理理论,结合AlN-BN复合陶瓷组成和结构特点,研究了AlN-BN复合陶瓷介电性能(介电常数,介电损耗角正切值)随测量温度,测量频率变化而发生变化的温度特性和频率特性。  相似文献   

7.
Ni—Al2O3复合电镀工艺   总被引:6,自引:0,他引:6  
在Ni-Al2O3复合电镀研究的基础上,用扫描电镜和X射线衍射方法对复合镀层表面形貌及微观结构进行了分析,采用高温实验检测镀层的润湿性。实验表明,搅拌速度和镀液中Al2O3的含量是影响复合量的主要因素,复合镀层的结构没有显著变化。复合镀层改善了铜基体与铁水的润湿性,作为功能性镀层用于冶金行业及钢铁厂。  相似文献   

8.
BN—YAION复合陶瓷的烧结行为   总被引:5,自引:0,他引:5  
对BN-YA1ON复便陶瓷进行了热压和无压烧结试验,对烧结体的密度变化和显微结构进行了研究,分析了影响BN基复合陶瓷致密化的主要因素。认为卡片房式结构是妨碍BN基复合陶瓷致密化的主要原因。热夺过程中施加的压力足够大时,可以破坏这种卡片房式结构,使片状BN定向排列,因而能获得高致密度的BN基复合陶瓷。热压过程中若有液相出现。,有利于片片BN定向排列,因而能促进BN基复合陶瓷的致密化。无压烧结时因不能  相似文献   

9.
催化剂对复合推进剂凝聚相反应热效应的影响   总被引:1,自引:0,他引:1  
应用热分析方法研究了CuO、Cr2O3、Co2O3及其碳酸盐的煅烧产物对AP/HTPB复合推进剂凝聚相反应热效应的影响。试验表明,绝大多数催化剂使推进剂的分解总热效应增大,使氧化剂AP与粘结剂HTPB间的界面反应明显增强,煅烧CuO与煅烧Co2O3在混合比为1∶2和1∶3(重量)时可有效地增强粘结剂的吸热分解反应  相似文献   

10.
莫尊理  陈红 《化学试剂》1999,21(6):329-330,331
报道了以相转移催化法合成一类新有机试剂-三乙氨基胺类树型配体N,N′,N″-(三苄基)-三乙氨基胺(TBAA)和N,N′,N″-(三苯甲酰)-三乙氨基胺(TBOAA),产率85%以上。此类化合物具有近似三角架形结构,能产生荧光,可以与稀土离子进行选择性配位。  相似文献   

11.
Ni—LDPE复合材料的研究   总被引:1,自引:0,他引:1  
报道了Ni-LDPE复合材料中镍粉含量对材料的导电性及力学性能影响的研究结果。实验表明,在低密度聚乙烯中加入片状镍粉以后,随着镍粉含量的增加,导电性上升,但力学强度先上升后下降。在镍粉体积分数为8%~15%时,电阻率急剧下降,然而力学强度仍然上升,直至达最大值后才急剧下降。这说明,在此期间镍粒子之间巳能充分接近、接触,形成导电通路;但是,如果聚乙烯份量太少,镍粒子被润湿、粘结不充分时,力学强度就会恶化。总之,复合材料的结构对其导电性及力学强度同时产生强烈的影响。  相似文献   

12.
本文以高密度聚乙烯(HDPE)为基体,以自制的h-G-C-2/1体系杂化填料为导热填料,制备了GNPs/CNTs/HDPE导热高分子复合材料,重点对比了杂化填料和复配填料对GNPs/CNTs/HDPE复合材料在导热、导电及力学性能方面的影响。结果表明,GNPs/CNTs/HDPE导热高分子复合材料的拉伸强度为31.9 MPa,冲击强度为22.1 kJ/m^2,体积电阻率为690 MΩ·cm,热导率为0.759 W/(m·K),满足集成电路封装用技术参数要求。杂化填料的分散性优于复配填料,杂化填料在提高复合材料的拉伸性能方面优于复配填料,复配填料在提高复合材料的热导率方面优于杂化填料。本文所获得的研究成果为制备新型综合性能优异的集成电路封装用导热高分子复合材料提供了一条新的思路。  相似文献   

13.
New thermally stable conducting materials can be obtained by dispersing conducting carbon black into poly(4,4′‐diphenylether‐1,3,4‐oxadiazole) (POD–DPE) solution in NMP. The blend preparation process resulted in quite good dispersed composite and a relatively low percolation threshold (around 5 wt % of CB). The effect of the compressive stress on the resistivity of composite has been evaluated. The resistivity decreases continuously as the applied pressure is increased. In addition to the electrical conductivity, the presence of carbon black resulted in higher thermally stable materials. The thermal stability, electrical conductivity, and pressure‐sensible characteristics make this conducting material a good candidate for application in manufacture of pressure sensors for high temperature ambient. This material shows a typical semiconductor behavior, characterized by an increase of conductivity with the temperature. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1631–1637, 2004  相似文献   

14.
以多壁碳纳米管(MWNT)为支撑材料,十二酸(LA)、十四酸(MA)、十六酸(SA)和十八酸(PA)为相变主材,采用熔融共混法制备不同成型复合相变材料。利用压片机、红外热成像仪、导热系数测试仪和电阻率测试仪对成型材料的物理性质、温度场分布、蓄-放热时间、导热率和电阻率进行测试。结果表明,成型压力和MWNT添加量对复合材料密度影响较小。4种有机酸中分别添加24%、19%、25%和26%的MWNT时,有机酸不会泄漏。成型后虽然温度场分布更均匀,且具有良好疏水性,但蓄热速度减缓。复合材料导热率分别比纯有机酸提高2.7~3.7倍、2.7~4.5倍、2.7~4.4倍和1.7~2.4倍。压力从1MPa变到11MPa时,复合材料电阻率分别减小75.9%、76.5%、72.2%和74.0%,材料电阻率变化曲线拟合表明两者之间相关性较高。说明制备的复合相变材料具有良好的疏水、导热和导电性能。  相似文献   

15.
With the development of soft electronics, conductive composites are garnering an increasing amount of attention. The electrical conductivity, thermal conductivity, and electrical stability of conductive composites are all very important. In particular, the thermal conductivity of conductive composites is critical to the stability of their conductive properties. However, little is reported on thermal management in conductive systems. Herein, sufficiently hydroxylated boron nitride nanosheets (BN‐OH)@polyaniline (PANI) composite nanosheets with a high thermal conductivity and outstanding conductance stability are reported. PANI nanowire arrays are aligned vertically on BN‐OH. This well‐ordered nanostructure provides the means to form a good conductive and thermally conductive path. Notably, the composite through‐plane thermal conductivity is 2.1 W m?1 K?1(≈1000% that of pure PANI) and that the resistivity of the composite is 1.38 Ω cm. Importantly, the resistivity of the composite remains unchanged after 1 h of work. The results show that this composite has prospective applications for use in soft electronics.  相似文献   

16.
In this work, a simple and novel method was applied to prepare polymer composites by taking the advantage of melt flow shear force driving orientation of the fillers. By using this method, hexagonal boron nitride/polyethylene (hBN/PE) and hexagonal boron nitride/carbon fibers/polyethylene (hBN/CF/PE) composites were fabricated to be possessed of high thermal conductivity and mechanical properties. A high thermal conductivity of 3.11 W/mK was realized in the composite containing 35 wt% hBN and 5 wt% CF, which was over 1,200% higher than that of unfilled PE matrix. Under this component, the compressive strength and modulus of hBN/CF/PE composite were determined to be 30.1 and 870.9 MPa, respectively, which were far higher than that of unfilled PE accordingly. The bending performance was also somewhat enhanced. Meanwhile, the bulk resistivity of the composite material reached 2.55 × 1011 Ω·cm, which was basically the same as that of pure PE. The novel composites with high thermal conductivity, excellent mechanical properties, and controllable electrical insulation could be a potential thermal management material for electrical and electronics industries.  相似文献   

17.
Adding conductive carbon fillers to insulating thermoplastic resins increases composite electrical and thermal conductivity. Often, as much of a single type of carbon filler is added to achieve the desired conductivity, while still allowing the material to be molded into a bipolar plate for a fuel cell. In this study, varying amounts of three different carbons (carbon black, synthetic graphite particles, and carbon fiber) were added to Vectra A950RX Liquid Crystal Polymer. The resulting single filler composites were tested for electrical resistivity (1/electrical conductivity) and thermal conductivity. In addition, the effects of single fillers and combinations of two different carbon fillers were studied via a factorial design. The results indicated that for the composites containing only single fillers, synthetic graphite, followed by carbon fiber, cause a statistically significant decrease in composite electrical resistivity. Composites containing only synthetic graphite, followed by carbon black, and then carbon fiber cause a statistically significant increase in thermal conductivity. For the combinations of two different fillers, the composites containing carbon black/synthetic graphite and synthetic graphite/carbon fiber had a statistically significant and positive effect on thermal conductivity. It is possible that thermally conductive pathways are formed that “link” these carbon fillers, which results in increased composite thermal conductivity. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers  相似文献   

18.
通过高温固相法在硬炭表面包覆沥青热解炭,制备锂离子电池负极材料。SEM测试显示,硬炭包覆上沥青热解炭后表面形貌发生了明显变化。由例得到,硬炭表面包覆的沥青热解炭的平均厚度为300nm。当硬炭表面包覆上沥青热解炭后(硬炭与沥青的质量比为2:1),首次库仑效率由55%提高到70%,可逆容量也有所提高。研究发现,硬炭在高倍率下的容量和循环稳定性比石墨好。  相似文献   

19.
Adding conductive carbon fillers to insulating thermoplastic resins increases composite electrical conductivity. Often, as much of a single type of carbon filler is added to achieve the desired conductivity and still allow the material to be molded into a bipolar plate for a fuel cell. In this study, various amounts of three different carbons (carbon black, synthetic graphite particles, and carbon nanotubes) were added to polypropylene resin. The resulting single‐filler composites were tested for electrical resistivity (1/electrical conductivity). The effects of single fillers and combinations of the different carbon fillers were studied via a factorial design. The percolation threshold was 1.4 vol % for the composites containing only carbon black, 2.1 vol % for those containing only carbon nanotubes, and 13 vol % for those containing only synthetic graphite particles. The factorial results indicate that the composites containing only single fillers (synthetic graphite followed closely by carbon nanotubes and then carbon black) caused a statistically significant decrease in composite electrical resistivity. All of the composites containing combinations of different fillers had a statistically significant effect that increased the electrical resistivity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

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