CuO掺杂对钇钡铜氧陶瓷电性能的影响

采用传统固相烧结法制备的Y_1Ba_2Cu_3O_(7-x)(YBCO)陶瓷为功能相、玻璃粉为烧结助剂、CuO为掺杂剂,制备了CuO掺杂的钇钡铜氧陶瓷。通过X射线衍射仪、扫描电镜、能谱分析仪、微欧仪和高低温交变湿热试验箱对其相组成、微观结构及电性能进行研究。研究结果表明:CuO掺杂有利于减少YBCO晶体结构中存在的氧缺陷;随CuO掺杂量从0%增加到3%,陶瓷致密度逐渐增加,电阻率明显降低; CuO掺杂量大于3%后,陶瓷致密度逐渐下降,电阻率也明显升高;随CuO掺杂量增加,陶瓷的电阻温度系数逐渐由负向正偏移,电阻温度系数值逐渐减小。当CuO掺杂量为3%时,样品的综合电性能最佳:电阻率为1. 55×10~(-4)Ω·m,电阻温度系数为-1 470×10~(-6)/℃。     

Cu/Ti3SiC2新型受电弓滑板材料的研究

选用具有高导电、高导热性的新型陶瓷Ti3SiC2作为弥散强化相,通过与Cu的混合,采用热压和无压烧结后制备成Cu/Ti3SiC2复合材料.该材料是一种具有优良性能的新型受电弓滑板材料.实验中分析了掺杂含量、保温时间及烧结制度等因素对复合材料基本性能的影响.     

GPS TiN-Si3N4复相材料制备及电加工性能研究

采用气氛加压烧结制备了Si3N4-TiN(Ni)复合材料,对材料的烧结性能,导电性能及电火花加工(EDM)的状况和机理进行了初步研究.结果表明:添加少量金属Ni一方面改善了材料烧结性能,一方面降低了Si3N4-TiN系统形成网络导电所需TiN添加量.其中添加20wt%TiN、4wt%Ni的试样,在1750～1800℃,1.2MPa氮气压力下保温一小时以后相对密度达97%,复合材料具有较好的力学性能及电性能,电阻率小于氮化硅基陶瓷可电火花加工的电阻率值1Ω穋m.对该配方试样进行电火花加工,加工性能良好,电加工机理为熔融.     

化学液相法制备BaPbO3导电陶瓷

采用化学液相法制备了ＢａＰｂＯ３陶瓷，通过Ｘ射线衍射、扫描电镜等手段分析了合成条件对粉末纯度的影响，了烧结条件对ＢａＰｂＯ３陶瓷组织结构及室温电阻率的影响。实验结果表明，２化学液相法制备的ＢａＰｂＯ３粉末纯度高、粒度细，由此粉末制备的ＢａＰｂＯ３陶瓷的室温电阻率达６．２８×１０＾－４Ω·ｃｍ，是一种很有前途的导电陶瓷材料     

PTC陶瓷掺杂高分子PTC材料的研究

研究了PTC陶瓷粉末掺杂高分子PTC材料的电性能,发现掺杂后复合材料的室温体积电阻率降低,PTC强度增加,这为解决高分子PTC材料中室温体积电阻率高与PTC强度低的矛盾提供了一条新的途径,同时发现绝缘高介陶瓷粉末对高分子PTC材料也有改善作用。另外,辐照交联可以很好地加材料的PTC强度和降低NTC强度。对实验现象从理论上进行了定性分析。     

Bi2O3掺杂堇青石陶瓷坯片与导电银浆共烧行为的研究

采用Bi2O3进行掺杂,成功地将堇青石陶瓷坯片的烧结温度降低到900℃。利用水基流延法制备堇青石坯片,研究了堇青石流延坯片的性能及其与导电银浆的共烧行为。结果表明,在900℃烧结的堇青石陶瓷坯片主晶相为α相,烧结试样具有良好的致密性和介电性能,且与导电银浆具有较好的共烧匹配性。     

稀土氧化物对SPS烧结AlN陶瓷电性能的影响

以AlN粉末为原料, 添加稀土氧化物(Sm₂O₃、Y₂O₃), 在氮气气氛下, 采用SPS烧结方法制备AlN陶瓷, 研究稀土氧化物的掺杂对AlN烧结试样相组成、微观结构和电性能的影响。实验表明: Sm₂O₃、Y₂O₃与Al₂O₃反应生成的液相稀土金属铝酸盐会提高AlN陶瓷致密度, 且在晶界处形成导电通路降低了AlN陶瓷电阻率。随着Sm₂O₃掺杂量的增加, 晶界相逐渐由Sm₄Al₂O₉过渡到SmAlO₃, 且Sm₄Al₂O₉对电阻率贡献最大。其中, 3wt% Sm₂O₃掺杂AlN陶瓷电阻率最低, 为      

泡沫碳化硅陶瓷的导电性能

采用高分子热解和反应烧结方法制备出泡沫碳化硅陶瓷，研究了泡沫碳化硅陶瓷的体积分数变化和钛的掺杂对泡沫碳化硅陶瓷骨架导电性能的影响．结果表明：随着泡沫碳化硅陶瓷的体积分数提高，泡沫碳化硅陶瓷的电阻率降低，这是泡沫碳化硅陶瓷筋中部碳化硅的面积增加所引起的；掺杂的钛转变成TiSi2导电相改善了泡沫碳化硅陶瓷的导电性能．TiSi2呈现离散和团聚两种形态分布，以不规则的形状位于碳化硅晶界之间，在碳化硅中作为施主杂质．泡沫碳化硅陶瓷表现出的正或负温度系数取决与掺杂的钛量的多少．     

氧化锌陶瓷铌掺杂效应的低温导电特性研究

研究了Nb2O5掺杂的ZnO陶瓷在低温下导电特性。结果表明：低温状态下．随着Nb2O5掺杂量的增加,ZnO电阻率降低,不同温度下烧结的ZnO样品,烧结温度越高,电阻率愈小;同一烧结温度下,不同烧结时间的ZnO样品,随着烧结时间的增加,电阻率愈小。     

微波介质陶瓷制备技术研究进展

总结了近年来微波介质陶瓷制备技术的研究进展。着重介绍了微波介质陶瓷在粉末制备和烧结方面的新技术,并分析了这些技术的主要优缺点,同时就烧结助剂对材料介电性能的影响进行了评述。最后指出了制备微波介质陶瓷目前存在的问题及今后的发展方向。     

Pulsed electric current sintering of electrically conductive ceramics

The processing of yttria-stabilised zirconia (Y-ZrO₂)-based ceramic nanocomposites by means of pulsed electric current sintering (PECS) is described. A nanometer-sized electrically conductive secondary TiCN phase was added to the insulating zirconia matrix in order to make the composite electrically conductive. The paper focuses on the importance of processing conditions and highlights the benefits of the PECS method as compared to more traditional hot pressing. The mechanical and microstructural properties of the ZrO₂–TiCN composites have been determined, and the benefits of using an electrical current to densify these composites were explained in terms of the evolution of the electrical properties of the densifying powder compact.     

反应烧结微米级SiC陶瓷材料的结构与力学性能

选用粒径为7μm的SiC粉体,采用反应烧结工艺制备致密的SiC陶瓷材料,研究了反应烧结SiC陶瓷材料的物相组成、显微组织结构与力学性能及其断口形貌。结果表明:通过优化制备工艺,SiC陶瓷素坯中的SiC颗粒和纳米炭黑粉体分布均匀,且具有三维联通的孔隙结构,有良好的硅熔渗性能。反应烧结SiC陶瓷材料中的SiC含量高,游离硅含量少,密度可达3.01g.cm-3,抗弯强度达到410MPa,洛氏硬度达到95HRA,综合性能达到陶瓷机械密封件的技术要求。     

碳化硅陶瓷导热性能的研究进展EI北大核心

SiC陶瓷具有优异的力学性能、热学性能、抗热震性能、抗化学侵蚀性能和抗氧化性能,是热交换器设备的常用基体材料。由于原料、成型工艺、烧成工艺和烧结助剂等因素制约,SiC陶瓷含有较多气孔、晶界、杂质和缺陷,导致其常温热导率(≤270 W·m^(-1)·K^(-1))低于碳化硅单晶材料(6H-SiC,490 W·m^(-1)·K^(-1)),且不同制备工艺下热导率存在较大差异。本文主要分析了温度、气孔、晶体结构和第二相对SiC陶瓷导热性能的影响,归纳了热压烧结法、放电等离子烧结法、无压烧结法、重结晶烧结法和反应烧结法制备高导热SiC陶瓷的特点,对优化烧结助剂种类及含量、高温热处理和添加高导热第二相等改善SiC陶瓷导热性能的主要措施进行阐述,并展望了未来高导热SiC陶瓷的研究方向,为未来制备低成本、高导热SiC质热交换器提供理论参考。     

Influential Factors on Electromagnetic Properties of Selected 3D Reticulated Ceramics

3D reticulated ceramics (3DRCs) with the composition containing SrFe12O19-SiC-TiO2 were prepared by a replication process with polyurethane sponges as the template in ceramic slurry. The electrical conductivity, dielectric and magnetic parameters of 3D reticulated ceramics (3DRCs) were measured with changes in cell size of the sponges, contents in the slurry and sintering temperature in this paper. Discussions about the influential factors of those parameters were focused on their electrical conductivity. The experimental results indicated that the electrical conductivity of 3DRCs raised with the increase of cell size, SiC/SrO.6Fe2O3 with weight ratio and sintering temperature. X-ray diffractions and SEM were used to investigate the relationship between electrical conductivity and sintering temperature. Deoxidizing reactions of SrO.6Fe2O3 caused the increasing electrical conductivity. The real part of permittivity (ε′) and imaginary part of permeability (μ") raised with the increase of electrical conductivity (σ). The imaginary part of permittivity (ε") has a maximum at 10° S/cm with the increase of σ, and the real part of permeability (μ′)changes slightly with the increase of σ. When σ is at the range of 10-4 S/cm to 100 S/cm (a semi conductive state),both the imagine part of permittivity and permeability raises with increasing σ, therefore, the 3DRCs present their high electromagnetic loss properties.     

反应烧结制备Si3N4/SiC复相陶瓷及其力学性能研究

以两种不同配比Y₂O₃/Al₂O₃ (A, 2:3; B, 3:1, 总量15 wt%)为烧结助剂, 通过添加不同质量分数的SiC粉体,反应烧结制备了高强度的氮化硅/碳化硅复相陶瓷。并对材料的相组成、相对密度、显微结构和力学性能进行了分析。结果表明: 在1700℃保温2 h情况下, 烧结助剂A 与B对应的样品中α-Si₃N₄相全部转化为β-Si₃N₄; 添加5wt% SiC, 烧结助剂A对应样品的相对密度达到最大值94.8%, 且抗弯强度为521.8 MPa, 相对于不添加SiC样品的抗弯强度(338.7 MPa)提高了约54.1%。SiC能有效改善氮化硅基陶瓷力学性能, 且Si₃N₄/SiC复相陶瓷断裂以沿晶断裂方式为主。     

Engineering porosity in silicon carbide ceramics

Porosity and microstructure control of the strut are essential for tailoring the properties of porous SiC ceramics. This study examined four different strategies for engineering the porosity of SiC ceramics: adjusting the template content, processing parameters, filler content, and sintering additive content. The suggested strategies offer substantial flexibility for producing SiC ceramics with engineered porosity, whereby the total porosity can be controlled effectively from 35 to 95%. These results suggest that combinations of the proposed strategies will be useful for the manufacture of porous SiC ceramics with engineered porosity.     

Tribology of SiC ceramics under lubrication: Features,developments, and perspectives

Silicon carbide ceramics have many outstanding properties like high hardness, high thermal conductivity, high strength, low density, good electrical conductivity, good chemical resistance, and excellent wear resistance. Because of their valuable properties, SiC ceramics are helpful in various tribological applications. In this paper, the features and developments of tribology of SiC ceramics under lubrication are reviewed. The relevant strategies to enhance the tribological performance of SiC ceramics under lubrication, including microstructures, mechanical properties, surface characteristics, external factors, and secondary phases, are comprehensively discussed. The tribochemical reactions and Stribeck curves of SiC ceramics are also presented. Finally, future research directions of SiC ceramics in the field of tribology under lubrication are proposed. This paper aims to offer some theoretical basis for the design of low-friction and low-wear SiC ceramics under lubrication in the future and a better understanding of SiC ceramics used as various tribological components under lubrication.     

烧结温度对TiO2压敏陶瓷非线性和介电性质的影响

基于一次烧结工艺,通过改变烧结温度,制备5种组分相同、(Sr,Bi,Si,Ta)掺杂的TiO2陶瓷试样.借助于伏安特性、介电频率特性、损耗频率特性及非线性系数的测定,研究烧结温度对TiO2基压敏陶瓷压敏和介电性质的影响.结果表明,在1200～1400℃范围内,随着烧结温度的降低,陶瓷的压敏电压降低、介电常数增大,同时非线性系数有所减小.兼顾陶瓷压敏和介电特性,烧结温度选择1350℃为宜.     

熔盐辅助合成Dy3Si2C2包裹SiC粉体及其陶瓷的烧结行为

碳化硅陶瓷因自身优良的物理化学性能而具有广泛的应用前景.碳化硅的化学键结合特性决定了其难以烧结成型,因此如何制备高质量碳化硅陶瓷是领域内的难点之一.本研究以三元稀土碳化物Dy3Si2C2作为新型SiC陶瓷的烧结助剂,依据Dy-Si-C体系的高温相转变原位促进碳化硅的烧结致密化.采用放电等离子烧结技术,利用金属Dy与Si...     

rGO/SiC复合材料的制备与性能研究

碳化硅(SiC)陶瓷具有优异的力学性能, 但是其断裂韧性相对较低。石墨烯的引入有望解决碳化硅陶瓷的断裂韧性较低的问题。本研究采用热压烧结工艺, 制备了具有不同还原-氧化石墨烯(rGO)掺入量的SiC复合材料。经过2050℃保温、40 MPa保压1 h后, 所制备的复合材料均烧结致密。对复合材料中rGO的掺入量、微观结构和力学性能的相互关系进行分析和讨论。加入4wt%的rGO后, 复合材料的三点抗弯强度达到564 MPa, 比热压SiC陶瓷提高了6%; 断裂韧性达到4.02 MPa•m^1/2, 比热压SiC陶瓷提高了54%。加入6wt%的rGO后, 复合材料的三点抗弯强度达到420 MPa, 略低于热压SiC陶瓷, 但其断裂韧性达到4.56 MPa•m^1/2, 比热压SiC陶瓷提高了75%。裂纹扩展微观结果显示, 主要增韧机理有裂纹偏转、裂纹桥连和rGO片的拔出。