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高能球磨对片状银粉的改性研究 总被引:4,自引:1,他引:4
采用高能球磨工艺,利用激光粒度仪、扫描电子显微镜、BET吸附等测试手段,研究了由化学法制备出的片状银粉在进一步细化过程中,银粉随球磨工艺参数的改变而变化的情况,讨论了不同球磨时间和不同分散剂对银粉粒度、形貌、比表面积等性能的影响。结果表明:球磨20h,使用无水乙醇作为分散剂,可制得平均粒径为2.5μm、比表面积为2.9m^2/g的超细片状银粉,满足电子浆料的使用需求。 相似文献
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《中国粉体技术》2016,(3):53-56
在永磁铁氧体细粉碎时添加分散剂,采用费氏粒度仪、黏度计、电泳仪等对永磁铁氧体料浆的分散性进行测试,利用沉降法比较料浆粒径及其分布,对生坯c晶面的取向度进行X射线衍射分析,采用永磁标准测量仪对永磁铁氧体元件的磁性能进行测试。结果表明:加入分散剂后,浆料的流动性、zeta电位值、生坯c晶面的取向度均得到明显的改善,提高幅度达18%以上;2组分的复配分散剂改善铁氧体生坯c晶面取向度的效果优于单一分散剂的,3组分复配的分散剂D改善浆料的流动性、zeta电位值、生坯c晶面取向度的效果最优,且在烧结后,永磁铁氧体元件的龟裂现象及其剩余磁感应强度、取向度、内禀矫顽力等磁参数也得到更显著的改善;添加0.5%~1.0%(质量分数)的分散剂D对铁氧体颗粒表面进行改性时,用氨水调节永磁铁氧体料浆的p H值为8~11时较理想。 相似文献
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为了提高分散作用效果,选用聚乙二醇-20000(PEG-20000)、十二烷基硫酸钠(SDS)及二者组成的复配分散剂,利用机械球磨与添加分散剂相结合的分散方法制备了钡铁氧体浆料,通过考察分散剂的用量、浆料的pH值、zeta电位对分散性的影响,根据红外光谱分析,研究了分散剂的分散效果及作用机理,并测定了分散前后磁场成型各向异性钡铁氧体材料的磁性能。结果表明:加入分散剂可以改善钡铁氧体的分散效果,且SDS和PEG-20000的用量为钡铁氧体质量的1%和2%时,分散效果最好。SDS和PEG-20000均为静电和空间位阻稳定作用。分散后磁场成型各向异性钡铁氧体材料的磁性能得到提高。 相似文献
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原料粒度对磷酸钙骨水泥性能的影响 总被引:1,自引:0,他引:1
以等质量的部分结晶磷酸钙(PCCP)和磷酸氢钙(DCPA)的混合物组成的磷酸钙骨水泥(CPC)粉体作为研究对象,采用单因素实验,研究了PCCP和DCPA粒度变化对骨水泥抗压强度、孔隙率、凝结时间、水化产物物相组成和结晶形貌的影响.结果发现:在0.4的液固比下,固定PCCP的粒度,减小DCPA的粒径,骨水泥的抗压强度呈先升高后减小的趋势,存在一最大值为34.6MPa;而PCCP的粒度变化对骨水泥性能的影响较大,随着PCCP粒径的减小,所需调和液的比例增到0.5,抗压强度也存在一最大值为19.7MPa.而孔隙率随这两种原料粒度变化的规律都与强度的变化规律相反,随原料粒径的减小,均存在一最小值.DCPA的粒度变化对骨水泥的凝结时间影响不大;而随PCCP颗粒粒径的减小,骨水泥的凝结时间变短.所生成的水化产物都为弱结晶的羟基磷灰石(HA),但当DCPA颗粒较粗时,固化体中有微量的DCPA残余;而当PCCP颗粒过细时,固化体中有较多的DCPA残余. 相似文献
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本文采用丝网印刷方法来制备钡铁氧体厚膜,研究了钡铁氧体浆料的成分对钡铁氧体厚膜表面形貌的影响,并讨论了排胶时间对其表面形貌的影响.研究结果表明,采用松油醇和柠檬酸三丁酯构成的混合溶剂可以有效改善钡铁氧体浆料的挥发特性,进而降低钡铁氧体厚膜的气孔率,提高厚膜的饱和磁化强度.通过降低有机载体的比例,可以提高钡铁氧体厚膜的致... 相似文献
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针对永磁铁氧体二次球磨问题,分析不同的环境温度对永磁铁氧体粉体湿法球磨的影响。结果表明,在较高的环境温度下进行球磨,球磨效率较高,粗颗粒和细颗粒较多,晶格缺陷较多,由此导致球磨时间缩短,磁性能降低,成品率下降,烧结收缩率增大;在球料质量比较大的情况下上述情况尤其明显。 相似文献
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Depending on milling conditions (air or vacuum) for the same milling time, a different level of decomposition and structure disorder in BaFe12O19 ferrite powders can be obtained by ball milling. Air-milled material has a tendency to form a gas-saturated disordered structure (superoxide) and to transform into simple oxides (reduction process through oxygen-saturated disordered phase) as opposed to the vacuum-milled powder where a highly disordered phase occurs. Both powders have a different morphology (particle size and distribution). Annealing processes produce crystalline barium ferrite phase with interesting magnetic properties, but in the present paper only structural transformations are analysed. Scanning electron microscopy, X-ray diffraction and thermal analysis techniques were applied to study the effects of heat treatment (10 h at 773 or 1273 K) in disordered BaFe12O19 ferrite powders prepared by 1000 h ball milling in air and vacuum. 相似文献
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The magnetic nano-structured Ba-Al ferrite powders were prepared by high energy ball milling under the conditions of various rotation rates and milling times. The micro structure was characterized by SEM, XRD and TEM, and the magnetic properties were obtained by VSM. As the rotation rate and milling time increased, the size of nano-sized particles gradually decreased. The high energy ball milling for 5 h without relation to the rotation rate drastically reduced the coercivity as a consequence of the formation of nano-sized particle with the amorphous structure. However, the coercivity gradually decreased with increasing the milling time, resulting from the decrease of particle size with maintaining the crystal structure. 相似文献
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AbstractHigh magnetic field was applied to fabricate novel lead-free piezoelectric ceramics with a textured structure. A compact of crystallographically oriented grains was prepared by dry forming in a high magnetic field from a mixed slurry of bismuth titanate and barium titanate powders. Bismuth titanate particles with a size of about 1 μ m were used as the host material. In the forming process, the slurry was poured into a mold and set in a magnetic field of 10 T until completely dried. Bismuth titanate particles were highly oriented in the slurry under the magnetic field. The dried powder compact consisted of highly oriented bismuth titanate particles and randomly oriented barium titanate particles. Barium bismuth titanate ceramics with a- and b-axis orientations were successfully produced from the dried compact by sintering at temperatures above 1100 ° C. 相似文献
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以柠檬酸和金属盐为原料,采用有机凝胶先驱体转化法成功制备了直径为500~600nm的钡铁氧体(BaFe12O19)微米纤维。通过XRD、SEM和VSM等技术对所制备的目标纤维进行了表征。结果表明,经750℃焙烧2h后,可获得M-Ba铁氧体纯相。随着焙烧温度的升高,晶粒逐渐长大,经850℃焙烧2h后,纤维主要由比较规则的片状晶粒组成。钡铁氧体纤维的磁性能主要受晶粒尺寸和测试温度的影响。经950℃焙烧2h后,组成纤维的晶粒尺寸约为62nm,室温下测得的饱和磁化强度和矫顽力均取得最大值,分别约为67A.m2/kg和328kA/m。在液氮(77K)条件下,纤维的饱和磁化强度有显著提高,最大值约为87A.m2/kg,这主要是由于纳米晶的表面自旋有序程度提高造成的。 相似文献
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M. M. Syazwan M. Hashim R. S. Azis I. Ismail S. Kanagesan A. N. Hapishah 《Journal of Materials Science: Materials in Electronics》2017,28(12):8429-8436
M-type barium ferrite with Mg–Ti substitution and MWCNT addition was synthesized using high-energy ball milling. The prepared sample was further analyzed using X-ray diffraction, field emission scanning electron microscope (FESEM), vibrating sample magnetometer and vector network analyzer. The results showed that the particle size had a wide range of distribution, and a hexagonal structure was formed in the sample. The sample was observed to have lower saturation magnetization and coercivity after Mg–Ti was substituted with MWCNT and added into the barium hexaferrite. Reflection loss was studied as a function of frequency and thickness of the sample. For Mg–Ti substituted barium hexaferrite composite with a thickness of 2.0 mm, the reflection loss peaked at ?28.83 dB at a frequency of 15.57 GHz with a bandwidth of 6.43 GHz at a loss of less than ?10 dB. The microwave absorption primarily resulted from magnetic losses caused by magnetization relaxation, domain wall resonance, and natural resonance. FESEM micrograph demonstrated that carbon nanotubes were attached to the external surface of the ferrite nanoparticles. The investigation of the microwave absorption indicated that with an addition of carbon nanotubes, the real and imaginary parts of permittivity and reflection loss had enhanced to ?34.16 dB at a frequency of 14.19 GHz with a bandwidth of 5.72 GHz. 相似文献
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The temperature dependence of the specific saturation magnetization of barium and strontium ferrite powders after milling in an attrition mill has been investigated at temperatures between -195°C and the Curie temperature of the ferrites. The experimental results show that the specific saturation magnetization decreases with increasing milling time and that a second, presumably soft-magnetic phase occurs during milling which vanishes during annealing of the powders. The influence of lattice defects introduced by the milling process is discussed. 相似文献
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Barium ferrite (BaFe2O4) nanoparticles were synthesized by auto combustion method under different weight percentages of barium. The role of barium in the behavior of spinel ferrite property is identified from this study. XRD exhibits prominent orientation of (212) for BaFe2O4 has confirmed especially in 20 and 30 wt% of barium. The addition of barium metal induced the specific vibration in FTIR spectra and such changes coincide well with the particle size. Further, the EDX spectrum reflects the atomic percentage of elemental presence in the samples of barium ferrite. Addition of barium on ferrite nanoparticles reduces the intensity of fluorescence. The morphological changes occurred due to increasing doping concentration of barium and is visualized from the FESEM and TEM images. The formation of different morphologies such as spherical, hexagonal platelets and small rectangular bar shape are observed only due to inclusion of barium at surfactant medium. The magnetic properties of the barium ferrite samples are studied by VSM. It reveals that 35.11 emu/g saturation magnetization (M s ) with 3775.08 Oe coercivity. The change in values of coercivity (H c ) from 3775.08 to 1572.95 Oe due to the variation of barium levels confirmed that the role of barium induced the hard magnetic behavior. The dielectric study also indicates the significance of barium ferrite in the variation of dielectric constant. 相似文献
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M. J. Molaei A. Ataie S. Raygan S. J. Picken F. D. Tichelaar 《Journal of Superconductivity and Novel Magnetism》2012,25(2):519-524
In this research, barium ferrite /magnetite nanocomposites synthesized via a mechano-chemical route. Graphite was used in
order to reduce hematite content of barium ferrite to magnetite to produce a magnetic nanocomposite. The effects of processing
conditions on the powder characteristics were investigated by XRD, VSM, and HRTEM techniques. XRD results revealed that milling
under air and argon atmospheres resulted in the appearance of Fe3O4 peaks beside BaFe12O19 peaks after 15 and 20 hrs milling, respectively. The intensity of Fe3O4 peaks in the XRD patterns increased by increasing the milling time. VSM studies revealed that saturation magnetization of
the 40-hrs milled samples under air and argon atmospheres was 31.25 and 36.42 emu/g, respectively. This difference might be
due to more Fe3O4 content in the latter sample. By annealing of the 40-hrs milled sample in air, saturation magnetization increased to 139.12
emu/g. 相似文献