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Zhang Jingfan Meng Lei Zhang Deliang Gao Wenpeng Fang Gongjun Luo Junjie Chen Wen 《Metallurgical and Materials Transactions A》2022,53(11):4126-4138
Metallurgical and Materials Transactions A - Two heat treatments, namely 955°C/2h/AC (AC = air cooling) and 955°C/4h/FC (FC = furnace cooling), were carried out on... 相似文献
3.
Zhaowu Wang Haipeng Ji Zongtao Zhang Jian Xu Deliang Chen 《Journal of the American Ceramic Society》2021,104(10):5077-5085
The cation exchange method has been demonstrated to be efficient in doping Mn4+ ions into various fluorides to synthesize the red-emitting LED phosphors. This paper, however, reports the challenge in using this method to dope Mn4+ into the Na2SiF6 single crystals, to prepare the fluoride phosphor in single-crystal form, a state-of-the-art study in the white LED lighting field. The millimeter-sized Na2SiF6 single crystals with a uniform columnar morphology (2–3 mm in length) were successfully grown in solution by a slow cooling process after optimizing the precursors. Then, the crystals were soaked in the HF solution dissolved with K2MnF6 to implement Mn4+-doping via the cation exchange process. Evaluation of the Mn4+-doping behavior reveals that the Mn4+ ↔ Si4+ cation exchange is less efficient in the case of single crystal host compared with the polycrystalline powdery ones and by-reactions also occur which generates new phases. The Na2SiF6 single crystals doped with Mn4+ exhibit a series of discrete sharp peaks with intense zero phonon line emission at 617 nm under 450 nm blue irradiation. This study may trigger the exploration of new single crystal fluoride phosphor. 相似文献
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提出了用纳米钴代替微米钴作为粘结剂的PDC复合片制备新方法及配套的制备新工艺,并对新型PDC复合片的微观组织结构及性能进行了研究。微观分析结果表明,纳米钴较于微米钴更密实地填充在金刚石颗粒间,有效促进了金刚石颗粒间D-D键的形成,且添加纳米钴的金刚石层对金刚石颗粒的把持力更好,同时纳米钴在金刚石层中形态较小且分布均匀,这些均对提高复合片综合性能有积极作用。性能测试结果表明,相对于传统复合片,新型复合片抗冲击性能提高了1.13倍,其耐磨性和热稳定性也得到了一定的提高,这与微观分析的结论一致。研究成果不仅为提升复合片综合性能提供了新思路,也对实现钻井提速增效、提高PDC钻头使用寿命有重要意义。 相似文献
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An improved CE/SE scheme for numerical simulation of gaseous and two-phase detonations 总被引:2,自引:0,他引:2
A new structure of solution elements and conservation elements based on rectangular mesh was proposed and an improved space-time conservation element and solution element (CE/SE) scheme with second-order accuracy was constructed. Furthermore, the application of improved CE/SE scheme was extended to detonation simulation. Three models were used for chemical reaction in gaseous detonation. And a two-fluid model was used for two-phase (gas-droplet) detonation. Shock reflections were simulated by the improved CE/SE scheme and the numerical results were compared with those obtained by other different numerical schemes. Gaseous and gas-droplet planar detonations were simulated and the numerical results were carefully compared with the experimental data and theoretical results based on C-J theory. Mach reflection of a cellular detonation was also simulated, and the numerical cellular patterns were compared with experimental ones. Comparisons show that the improved CE/SE scheme is clear in physical concept, easy to be implemented and high accurate for above-mentioned problems. 相似文献
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用固相反应方法合成了Na5YSi4O12的纯相样品。用XRD及SEM研究了合成反应过程,对反应过程的中间状态及组成进行了比较,给出了消除杂相,得到致密纯相NYS样品的方法。 相似文献
8.
Deliang Zhu Peijiang Cao Wenjun Liu Xiaocui Ma Xiaojun Bai A. Maignan B. Raveau 《Materials Chemistry and Physics》2006,100(2-3):472-476
The magnetic and transport properties of Pr0.5Ca0.5−xAxMnO3 (A = Sr, Ba) have been investigated in this paper. The substitution of Ca with bigger cations such as Sr and Ba can favour the field-induced ferromagnetism and induce sharp steps in the magnetization versus field and resistivity versus field curves. These properties strongly depend on the thermal history of the samples. All the results have been interpreted by a martensitic-like mechanism based on phase separation induced by A-site size mismatch. The above model can also explain the result that the less efficient ability of Sr substitution than Ba substitution to induce ferromagnetism and sharp steps. Another interesting feature in the system is the existence of an optimum substitution range to induce magnetization steps and reach high field-induced magnetization values for both Sr (x = 0.07–0.10) and Ba (x = 0.01–0.08) substitution. We suggest that the disappearance of the steps beyond the optimum substitution range possibly results from the different nature of phase separation in the optimum substitution range and beyond this range. 相似文献
9.
符合SCORM标准的SMIL可共享内容对象的研究 总被引:1,自引:0,他引:1
根据W3C推荐标准SMIL2.1,结合HTML+TIME2.0规范具体设计符合SCORM2004标准的SMIL-Enabled可共享内容对象。不仅使学习内容对象具有高水平的互操作性、可访问性和可重用性,更重要的是将多媒体的控制、表现与素材分开,轻松同步各种多媒体元素,并进一步增强了资源的可重用性。 相似文献
10.
采用N离子注入金刚石膜和热解石墨方法合成了CNx膜,用Raman光谱和XPS谱对合成薄膜中C、N的化学键合状态进行了研究.通过与Raman光谱的比较,我们对合成样品XPS谱中N1s的化学键合状态作出如下归属:≈400.0 eV属于sp2 C-N键;≈398.5 eV则属于sp3 C-N键.结果显示:碳原子、氮原子间的化学键合状态,明显地依赖于衬底材料及注入N离子的能量. 相似文献