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采用固相烧结工艺制备了SrxBa1-xBi4Ti4O15铁电陶瓷和SrBi4Ti4O15/BaBi4Ti4O15铁电复合材料。在固相反应过程中,680℃时SrBi4Ti4O15或BaBi4Ti4O15开始生成:800℃时材料主晶相基本形成,但是还有微量焦绿石相存在;850℃时SrBi4Ti4O15或BaBi4Ti4O15的主要衍射峰全部出现。随着Ba含量的增加,SrxBa1-xBi4Ti4O15陶瓷的居里温度逐渐降低。Sr0.5Ba0.5Bi4Ti4O15,陶瓷的介电常数峰在高频时较宽,在100Hz时,介电常数峰被随温度升高而逐渐增大的介电常数所“屏蔽”,材料介电损耗随温度升高而增大,但在低频下增加得更快,这是高温下由氧空位引起的电子松弛极化造成的。将预烧后的SrBi4Ti4O15和BaBi4Ti4O15粉体分别造粒后冉均匀混合,压片成型,经烧结制得的SrBi4Ti4O15/BaBi4Ti4O15复合陶瓷其相变弥散特性明显优于SrxBa1-xBi4Ti4O15的相变弥散特性。 相似文献
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DING Yimin HOU Na CHEN Nianyi XIA Yiben 《稀有金属(英文版)》2006,25(4):316-320
The phase diagrams of the Li2MoO4-Na2MoO4 and Na2MoO4-K2MoO4 systems have been reassessed using differential thermal analysis together with high-temperature and room-temperature X-ray diffraction analysis. The results showed that the compound Li2MoO4.6Na2MoO4 did not exist; however, it confirmed the existence of the compound Li2MoO4.3Na2MoO4 in the Li2MoO4-Na2MoO4 systen'ls. With regard to the system of Na2MoO4-K2MoO4, we could not confirm the results reported by Bukhanova who claimed that the system was eutectic type with 1:1 and 1:2 intermediate compounds, refuting the statement of Amadori who thought there was an apparent phase boundary at high temperature in α-solid solution region of the Na2MoO4-K2MoO4 binary system. The revised phase diagrams of these systems are illustrated in this article. These experimental results are in agreement with the computerized prediction using the support vector machine-atomic parameter method for the assessment of phase diagrams. 相似文献
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《中国有色金属学会会刊》2006,16(4):887-891
Initial atmospheric corrosion of zinc in the presence of Na2SO4 and (NH4)2SO4 was investigated via quartz crystal microbalance(QCM) in laboratory at relative humidity(RH) of 80% and 25 °C. The results show that both Na2SO4 and (NH4)2SO4 can accelerate the initial atmospheric corrosion of zinc. The combined effect of Na2SO4 and (NH4)2SO4 on the corrosion of zinc is greater than that caused by (NH4)2SO4 and less than that caused by Na2SO4. Fourier transform infrared spectroscopy(FTIR), X-ray diffractometry(XRD) and scanning electron microscopy(SEM) were used to characterize the corrosion products of zinc. (NH4)2Zn(SO4)2, Zn4SO4(OH)6·5H2O and ZnO present on zinc surface in the presence of (NH4)2SO4 while Zn4SO4(OH)6·5H2O and ZnO are the dominant corrosion products on Na2SO4-treated zinc surface. Probable mechanisms are presented to explain the experimental results. 相似文献
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Fabrication of CTP/HAp novel gradient composite bioceramics 总被引:1,自引:0,他引:1
Calcium-titanium-phosphate(CaTi4(PO4)6, CTP)/hydroxyapatite(HAp) is a kind of novel gradient composite bioceramics, which has excellent biocompatibility and bioactivity. CTP ceramic film was synthesized one-step on the surface of titanium using micro-arc oxidation(MAO). The CTP/HAp composite bioceramics were prepared by soaking CTP film in HAp inducing solution for several days. XRD, SEM and EDX were used to characterize the bio-ceramic films phase and composition, morphology and component. The influence of electrolyte molar ratio of Ca to P and the current density to the synthesis of film was studied, and the optimized value of parameters above were 1/6 and 15A/dm^2. The parameters of HAp inducing solution, such as component and pH value were also studied and the best pH value which is adjusted by NaOH is 6.4. 相似文献
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W4Mo3Cr4VSi钢棒矫直断裂原因分析@徐文峰$汉江工具有限责任公司十四分厂!陕西汉中723002
@廖晓玲$汉中农校化学组!陕西汉中723001~~ 相似文献
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摘要:采用固相烧结工艺制备了SrBi4Ti4O15(SBTi)/Ag铁电复合材料,通过X射线衍射、光学金相显微镜和扫描电子显微镜对材料的组成和微观结构进行了研究,并测量样品的介电温度谱。结果表明:复合材料是由SBTi和Ag两相组成。微量金属Ag的加入使SBTi铁电陶瓷的烧结温度从1120℃降低到950℃以下:可以适当提高铁电陶瓷从室温到200℃的介电常数,但对材料的介电损耗影响很小。同时Ag的加入压抑了介电温度曲线上的介电常数的Curie峰。 相似文献
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以铝粉、石墨粉和有机物聚碳硅烷(PCS)为原材料,采用预裂解及原位反应热压烧结的方法制备了Al4SiC4块体陶瓷.通过XRD,SEM,TEM及力学性能分析等测试手段对材料的结构及性能进行了分析研究.原料预裂解粉的XRD分析结果表明原料在预裂解后,反应产品主要为Al4C3和SiC的混合粉末.将预裂解后的Al4C3和SiC混合粉进行热压烧结,烧结产品经XRD分析表明最终物相主要为Al4SiC4相.Al4SiC4陶瓷的微观组织观察表明,Al4SiC4粒子形貌为板片状,在{0001}基面上分布有大量的层错.Al4SiC4陶瓷的室温弯曲强度随烧结温度的升高而增加,而断裂韧性则随烧结温度的升高而降低. 相似文献
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介绍了00Cr14Ni14Si4钢的焊接工艺试验,并提出了保证焊接质量的工艺措施,成功地应用于N2O4冷凝器的焊接。 相似文献
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针对热轧板凸度控制问题,研究了轧制负荷、弯辊力、轧辊热膨胀、原始辊凸度、轧辊磨损、边缘降及楔形对板凸度的影响.结果表明,F3、F6机架负荷减小、F2、F4与F5机架负荷增大、弯凸度力增大、辊凸度减小、边缘降减小及楔形绝对值减小均可使带钢板凸度减小,轧辊热凸度约30min基本形成,轧辊不均匀磨损直接影响带钢板凸度. 相似文献
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针对中厚板热轧时出现的边裂缺陷,研究了其形成原因及控制方法。结果表明,铸坯表面的微裂纹和轧件的不均匀变形是边裂产生的主要原因,通过调整加热及轧制工艺参数、优化轧机配辊等措施可有效控制板材边裂缺陷的产生 相似文献
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为了提高冷轧薄板的成材率,研究了冷轧薄板表面条痕缺陷的宏观和微观特征,提出夹杂物、铸坯表面裂纹、气泡是形成表面缺陷的主要原因。严格工艺操作可减少或消除缺陷。 相似文献
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