湿法磷酸脱除金属离子的研究

对氨中和沉淀法脱除湿法磷酸中金属离子进行了实验室和中试研究。优化工艺条件为:氨与P_2O_5质量比15.08%~20.78%,反应温度88~95℃,反应时间0.5~1.0 h,净化磷酸澄清时间≥48 h。中试结果表明,所采用的流程是合理可行的,在一定程度上解决了磷矿品质下降和金属离子升高对磷酸生产及磷肥产品质量的影响。     

Synthesis of metal‐free poly(p‐dioxanone) by phosphazene base catalyzed ring‐opening polymerization

Poly(p‐dioxanone) (PPDO) has received significant attention due to its good biocompatibility and fast biodegradation profiles. In addition, PPDO is a polymer with high potential in biomedical applications. However, the conventional syntheses of PPDO via the ring‐opening polymerization (ROP) of p‐dioxanone (PDO) often use a metallic catalyst, which significantly limits its biorelated applications. This investigation was focused on the synthesis of metal‐free PPDO by using phosphazene base t‐BuP₄ as the catalyst. The effects of the reaction conditions including temperature, reaction time, initiators, and feed molar ratios were studied in detail by nuclear magnetic resonance spectroscopy, viscosimetry, differential scanning calorimetry, and thermogravimetric analysis. The results showed that t‐BuP₄ exhibited especially high activity in catalyzing alcohol or aniline to initiate the ROP of PDO, consequently resulting in metal‐free PPDOs. The polymerization was optimum at a reaction temperature of approximately 100°C and 88.7% of PDO was consumed. The viscosity–average molecular weights of the resulting polymer reached as high as 2.09 × 10⁴ g/mol. The molar ratios of [PDO]/[t‐BuP₄] also had an obvious effect on both the polymerization and the resulting polymer. Increasing [PDO]/[t‐BuP₄] ratios facilitated the molecular weight growth, whereas the conversions of PDO significantly decreased. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43030.     

Structural Transitions Induced by Ion Irradiation in V2AlC and Cr2AlC

Nanolayered structural metallic ceramics, MAX phases, possess unique and highly attractive properties, including excellent radiation tolerance for some of them, whereas little is known about the detailed process of irradiation‐induced structural transitions. In this study, the microstructural transformations and the stabilities of V₂AlC and Cr₂AlC induced by 1 MeV Au⁺ ions irradiation over a wide range of fluences were investigated by grazing incidence X‐ray diffraction (GIXRD) and transmission electron microscopy (TEM). GIXRD analyses show different processes of phase transitions and amorphization tolerance under irradiation between these two MAX phases, which are consistent with the selected area electron diffraction (SAED) results and the high‐resolution observations. TEM observations reveal that the nanolamellar structures are disturbed and respective phase transitions occur at relatively low fluences, with the formation of stacking faults. As the fluence increases, Cr₂AlC becomes completely amorphous, while V₂AlC are gradually transformed into face‐centered cubic (fcc) structure from the original hexagonal close‐packed (hcp) structure without amorphization, indicating that V₂AlC is more tolerant of irradiation than Cr₂AlC. Based on the phase contrast images and the electron‐diffraction pattern (EDP) simulation of the microstructures, mechanisms of the phase transitions of V₂AlC and Cr₂AlC are proposed and the difference of the irradiation tolerance between them is discussed.     

Glucose‐sensitive and blood‐compatible nanogels for insulin controlled release

For insulin delivery, many reported glucose‐sensitive materials are designed to response to the glucose in the blood. However, few particular studies on their blood compatibility have been reported. In this article, for controlled insulin release in diabetes therapy, a glucose‐sensitive nanogel was prepared through thermally initiated precipitation polymerization using the aminophenylboronic acid‐containing monomer to copolymerize with methacrylic acid. The obtained nanogels showed the uniform and spheroidal morphology as observed by SEM, and their sizes in aqueous solution are dependent on the concentration of glucose. Through in vitro and in vivo insulin release tests, it was found that nanogels showed the glucose‐dependent insulin release and prolonged effect of lowing blood glucose level. The blood compatibility of nanogels has also been explored through various assays including the hemolysis, activated partial thromboplastin time, prothrombin time as well as the thromboelastography. All results indicated that the obtained glucose‐sensitive nanogels showed good blood safety. Moreover, their low cytotoxicity suggested a potential application in diabetes therapy. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43504.     

The performance of chitosan/gelatin composite microspheres in the wash‐off procedure of reactive dyeing

A chitosan/gelatin composite microsphere (CGMS) adsorbent prepared by inverse suspension was used as a reactive dye washing agent. Techniques such as scanning electron microscopy, X‐ray diffraction analysis, and atomic force microscopy facilitated the evaluation of the materials. A series of experiments were conducted to assess the effect of variables, i.e. initial pH, temperature, microsphere dosage, and contact time. The wash‐off effectiveness increased with increase in temperature and decrease in pH. Results obtained from this study showed that it was possible to reduce the number of wash‐off stages and the water consumption. Furthermore, the microspheres had the properties of resistance to hard water and electrolyte as a wash‐off agent. The efficiency of the microspheres can rival routine detergent in colour fastness, while the chemical oxygen demand of the wash‐off residue of the microspheres amounted to about 1/10 of the chemical oxygen demand of detergent wash‐off residue. This research proved that chitosan/gelatin composite microspheres are a potential candidate for use as an adsorbent washing agent for reactive dyes.     

不同温度时效后Ni-20Cr-18W-1Mo合金晶界偏聚及力学性能研究

采用扫描电镜(SEM)、透射电镜(TEM)、电子探针(EPMA)和高温力学试验机等手段,研究了不同时效温度(200-800 °C)对Ni-20Cr-18W-1Mo高温合金的元素晶界偏聚和力学性能的影响。结果表明,硫、磷元素的晶界偏聚临界时间随时效温度升高而降低;时效温度对元素在晶界和晶内的成分分布有显著的影响;实验合金的抗拉强度和延伸率随时效温度升高而降低。分析发现,硫、磷元素在晶界中的含量随时效温度升高而增大直至两者分别在650和400 °C时达到峰值,是合金在200-600 °C区间内力学性能降低的重要原因。     

镍基合金环境致裂过程中裂尖微观力学特性分析

核电站一回路压力容器、管道及蒸汽发生器等设备和结构中广泛采用镍基合金和奥氏体不锈钢,而这些材料的环境致裂(EAC)却是核电结构的主要安全隐患之一。研究表明,核电高温高压水环境中镍基合金的EAC是裂尖氧化膜破裂和再生成的一个过程。为了深入了解镍基合金EAC裂纹扩展过程中裂尖的力学状况,本文从理论和数值模拟两方面分析研究了EAC裂尖氧化膜和基体金属区域的应力分布规律,为提高定量预测高温高压水环境中镍基合金EAC扩展速率精度奠定基础。     

Si元素对Al-40Zn-xSi 钎料组织和性能的影响

研究了Si元素对Al-40Zn-xSi 钎料的钎焊性能,显微组织的影响以及不同Al-40Zn-xSi钎料对铝合金钎焊接头的显微组织和力学性能的影响。结果表明：当Al-40Zn-xSi中Si元素含量为4%时,钎料具有最好的润湿性能。显微组织分析表明：当Si元素含量超过4%后,钎料中开始出现块状初生硅;铝合金钎焊接头水冷后,Al-Si共晶组织和Zn-Al共析组织共存于焊缝中α-Al 的枝晶间区域。当钎料中Si元素的含量为4%时,焊后水冷的铝合金钎焊接头的抗剪强度达到最大值142.28 MPa。但是,当钎料中Si元素含量为5%以上时,焊缝中会形成较多的脆性共晶组织和初生硅颗粒,影响接头力学性能。     

钨螺旋线表面镀金薄膜热可靠性研究

钨螺旋线是行波管的关键部件,随着行波管功率量级和工作频率的不断提高,其高频损耗和散热问题更加突出。为了提高钨表面镀金薄膜均匀性和结合力,前期研究了钨螺旋线表面镀覆金膜的方法,并在高温使用条件下测试镀金膜的热稳定性。采用纳米划痕技术测试镀金薄膜和基体之间结合力大小,对预镀铜5,10,15和20 s,镀金均为1.5 h后的试样高温(500℃,100 h)处理前后的膜-基结合力进行了对比分析。结果表明:预镀铜5,15和20 s的试样经高温处理后的膜-基结合力大小与室温下相比没有明显降低;预镀铜10 s时的试样经高温处理后的膜-基结合力与室温下相比有所增大。钨螺旋线表面镀金薄膜热可靠性好。