激光熔覆稀土磷酸钙陶瓷涂层及其在生理盐水中的降解行为

利用激光熔覆技术,在医用钛合金表面制备梯度稀土磷酸钙复合陶瓷涂层。采用OM、XRD、SEM、iCP-MS分别对涂层的界面结合、物相组成、显微形貌、离子溶出进行考察。结果表明:经过激光熔覆后,能够在钛合金表面得到富含HA和β-TCP的梯度磷酸钙陶瓷涂层,且涂层分为基材、合金化层、陶瓷层3个层次,各层间界面结合良好;磷酸钙陶瓷涂层不断被生理盐水降解,质量不断丢失,涂层在生理盐水中能够形成一种类骨磷灰石的新相;伴随着涂层的降解,Ca~(2+)和La~(3+)从涂层中溶出;溶液中Ca~(2+)的溶出浓度在15~40 mg/L的范围内随浸泡时间的延长呈现波动上升的趋势,La~(3+)的析出浓度却在0.15~0.45 mg/L之间随着浸泡时间的延长呈现波动下降的趋势。     

可降解锌基骨植入材料及其表面改性研究进展

医用锌及锌合金有望成为新一代可降解骨植入物材料来促进骨缺损的修复。概述了可降解医用锌基材料的优势,包括较好的生物安全性和抗菌效果、能促进植入部位周围血管和新骨的生成以及骨相关基因的表达能力。在此基础上,从基底材料、细胞种类及实验结果等方面系统总结了近年来关于可降解医用锌基材料生物相容性和降解行为的研究。同时,归纳了可降解医用锌在临床修复骨缺损方面所面临的主要问题和挑战,包括较差的力学性能和较强的细胞毒性。可降解医用锌较差的力学性能可以通过合金化进行改善,概述了多种新型医用锌合金的力学性能及其生物相容性。表面改性是提高可降解医用锌基表面生物相容性和调控降解的有效手段。从基底样品、表面改性手段、使用的细胞或动物模型以及细胞相容性和降解行为等方面,综述了近年来可降解锌基骨植入材料表面改性的研究现状,提出了可降解锌基骨植入材料表面改性目前所面临的难点问题,包括传统表面改性手段加剧了锌离子的释放或在表面改性后可降解医用锌的生物相容性改善功效不足,以及未来的发展方向。     

可溶性陶瓷纤维的生物降解性

通过3种可溶性陶瓷纤维在Gamble溶液中的溶解,研究了可溶性陶瓷纤维生物降解性.结果表明随着纤维溶解时间增加,Gamble溶液的pH值增加.纤维组分中的CaO,MgO,SiO2在Gamble溶液中均有较大的溶解度.在Gamble溶液中,纤维组分中的SiO2比CaO,MgO溶解速率大的多,Al3+和Fe3+的浓度基本不变.国外研制的纤维和国内的纤维的溶解性能很相似.CaO-MgO-SiO2系陶瓷纤维在Gamble溶液中显示了较高的生物可溶性.     

金属阳离子对医用镁合金降解行为的影响规律

医用镁合金的降解特性直接影响其在心血管支架和骨替换材料等领域的应用。本研究在保持与生理体液氯离子浓度一致的基础上,选用镁合金AZ31B分别浸入NaCl溶液,KCl溶液,MgCl2溶液和CaCl2溶液中,对比研究金属阳离子对医用镁合金的降解行为影响。通过动电位极化曲线和电化学阻抗谱测试分析,发现镁合金浸泡在4种氯盐溶液时的腐蚀电位、阻抗与其在降解过程中溶液pH变化、样品失重变化趋势一致,即金属阳离子直接影响医用镁合金的降解特性:NaClKClCaCl2MgCl2,其中Na+和K+比Ca2+和Mg2+更能促进镁合金降解。     

纳米磷酸钙复合骨支架体内降解的实验研究

研究纳米磷酸钙复合氧化铝氧化镁生物玻璃骨组织工程支架在动物体内的降解特性,为进一步构建组织工程化纳米人工骨提供研究依据;本研究将合成灭菌后的纳米磷酸钙复合骨支架植入新西兰大白兔股部肌袋,并在植入4、8、12、16 w取材进行大体、组织学、电镜观察降解情况,16 w时将取出的材料煅烧,测量残余无机物含量,同时进行X线衍射实验,测量残余材料的晶相组成.结果是:合成的纳米磷酸钙复合骨支架孔隙率为80%,孔径200～450 μm,抗压强度为3.8 MPa.材料在动物体内前8 w内降解较慢,生物力学强度减低不明显,12 w后降解明显加速,强度明显减低,并有羟基磷灰石成分出现,煅烧后残余无机物最少,16 w明显新骨形成,降解残余材料分布于新形成的骨组织内部,羟基磷灰石成分明显增多.结论显示纳米磷酸钙复合骨支架具有较好的降解性、生物相容性和诱导成骨作用,可作为骨组织工程的支架材料.     

溶胶凝胶法制备氧化铝纤维的研究（英文）

以硝酸铝和铝粉为原料,采用溶胶凝胶技术制备了氧化铝长纤维。通过FTIR,EDS,TG-DSC和SEM等手段对纤维先驱体凝胶的结构组成、热分解过程及纤维形貌进行了表征。研究表明凝胶可纺性与A1/AN的摩尔比、前驱溶液的pH以及助纺剂的加入密切相关。当Al/AN的摩尔比为2,溶液pH在3.2~3.5之间得到的凝胶粘度在40~80 Pa·s时具备较好的成纤性。最后得到的烧成纤维直径10~30μm,长径比为(0.2~1)×10~4。     

连续电纺纳米纤维自动调匀控制方法

目前在连续电纺纳米纤维的制备过程中,难以保证纤维直径的高均匀度,制备的纳米纤维在高性能场合应用需要进行第二道调匀工序。为了解决这一问题,通过建立纳米纤维收集辊运动控制模型,提出一种偏振误差补偿方法,有效解决了由纤维收集辊转动微偏震造成的纤维直径不均匀的问题,实现了纳米纤维的自动调匀,制备的纳米纤维直径均匀度达到99.9%。     

新型生物可降解Fe-30Mn-1C合金的性能研究

采用真空感应熔炼法制备了Fe-30Mn-1C合金,研究了其力学性能、磁性、模拟体液中的降解速度以及体外生物相容性.研究结果表明,与Fe-30Mn合金和316L不锈钢相比,C的加入提高了铁基合金的力学性能,使材料兼具高强度和高塑性,并进一步降低了材料的磁性,使其具有更优良的核磁共振(MRI)兼容性.电化学阻抗谱(EIS)结果表明,材料的极化电阻降低,浸泡实验也证实材料的降解速度得到提高.体外生物相容性研究结果表明.Fe-30Mn-1C合金同时具有优异的抗溶血、凝血、血小板黏附性能,以及良好的细胞相容性,满足对医用植入材料的基本要求.     

Ni^2＋-C2H8N2-2-24CO-H2O体系的热力学分析及Ni微米纤维的制备

根据同时平衡和质量平衡原理,建立了Ni2＋-C2H8N2-2-24C O -H2O体系的沉淀-配合平衡热力学模型,并对该模型进行计算来揭示该体系中各物种浓度随pH值、草酸及乙二胺浓度的变化规律。结果表明,当pH〈1和pH=1-6时,溶液中的Ni分别主要以游离Ni2＋及[Ni（C2O4）n]2-2n形式存在。当pH〉6时,Ni2＋与乙二胺的配合作用占优势。当用乙二胺作配位剂,采用草酸盐沉淀法制备了 Ni 微米纤维前驱体,并讨论了乙二胺在前驱体生长机制中的作用。将前驱体在N2和H2混合气氛中热分解还原,可得到直径0.2-1μm、长径比20-30的Ni微米纤维。     

控制含钇碳化硅纤维直径及纤维性能

通过乙酰丙酮钇与聚碳硅烷反应,得到分子量适中(Mw=2816)、GPC曲线呈双峰分布、具有优异可纺性的新型先驱体含钇聚碳硅烷,在控制纺丝温度和压力后,得到表面光滑、无裂纹、直径为5.3 μm的原纤维.讨论了原纤维直径对纤维制备工艺及性能的影响.降低纤维直径,有利于减少纤维缺陷,提高纤维强度和柔顺性.当纤维直径为6.20 μm时,抗张强度为3.52 GPa,且随直径减小,抗张强度呈线性增长趋势,为制备新型含异质元素耐超高温SiC纤维奠定了基础.     

AZ31镁合金在人工血浆中的动态降解行为

通过AZ31镁合金在人工血浆中的浸泡实验和动/静态降解析氢实验,研究了AZ31镁合金的动态降解行为。人工血浆溶液的循环更新对镁合金的降解具有一定的影响,溶液的更新可以保持其pH值的稳定,促进镁合金的降解;在动/静态降解析氢实验中,对镁合金表面降解形貌的扫描电镜(SEM)观测表明,镁合金在动态实验中除了点腐蚀行为外,还存在冲刷腐蚀。由析氢速率对比结果显示,镁合金在人工血浆中动态实验比静态实验的降解速率更快。     

Fatigue strength of 316L-type stainless steel in simulated body fluids

The fatigue strength of commercial SUS316L stainless steel was studied in PBS(−) (phosphate buffer solution) with different dissolved oxygen contents and CPBS (a 0.9 mass% NaCl-containing citric phosphate buffer solution) with different pH levels, i.e., 5.0, 6.0, and 7.5. The results obtained are as follows. (1) The fatigue behaviour in PBS(−) was hardly affected by the dissolved oxygen content. (2) The fatigue strength in a high-cycle region was much lower in CPBS of pH 7.5 than in PBS(−) of pH 7.5. (3) The fatigue strength in CPBS decreased with decreasing pH from 7.5 to 5.0.     

免水洗常温热镀锌表面磷化技术研究

以磷酸、氧化锌、磷酸二氢锰、钼酸铵和硝酸钙等为原料,通过正交试验等方法开发了一种磷化后免水洗的常温热镀锌表面磷化液。研究了磷化液的pH值、磷化温度、磷化时间以及自干时间等对磷化膜质量的影响。结果表明:磷化液pH值为2.6～3.3,在5～40℃浸渍磷化7～10min,自然干燥3h可获得磷化后工件免水洗的磷化膜。磷化膜的耐蚀时间超过50s,喷涂铁红环氧底漆后的漆膜附着力达1级。     

Enhanced visible-light-response photocatalytic activity of bismuth ferrite nanoparticles

Multiferroic BiFeO₃ nanoparticles were prepared by a sol-gel rapid calcination technique with average diameter of 35 nm with narrow size distribution. The band gap was determined to be 2.06 eV, indicating their potential application as visible-light-response photocatalyst. The photocatalytic behaviors of BiFeO₃ nanoparticles were estimated by the degradation of Rhodamine B (RhB) under visible light irradiation. And the photocatalytic activities under different pH values were further studied for the first time. The result shows that the BiFeO₃ nanoparticles exhibit the highest photocatalytic activity in the solution with the lowest pH value, almost 100 times higher than that of the bulk.     

光催化剂载体— — —羧基氟碳共聚物纤维膜的制备及耐光降解性能研究

以甲基丙烯酸十二氟庚酯(DHFMA)和甲基丙烯酸(MAA)为单体,通过溶液聚合制备出MAA含量不同的羧基氟碳共聚物(DHFMA-co-MAA),并通过静电纺丝装置制备了羧基氟碳共聚物纤维膜。研究了MAA含量和溶剂对纤维膜形貌的影响,分析了纤维膜的耐光降解性能,结果表明:MAA含量25%的DHFMA-co-MAA以DMF作为纺丝溶剂,MAA含量10%的DHFMA-co-MAA以丁酮+DMF(质量比为2∶8)作为纺丝溶剂,均可以制备出表面平滑、纤维直径较小、形态均一的纤维膜;MAA含量10%的DHFMA-co-MAA纤维膜的光稳定性能更好,更适合用作光催化剂载体。     

镁合金在碳酸饮料中的降解与人体补镁初探

提出了通过镁产品在饮用水中的镁离子释放作为人体补镁手段的新思路,分析了镁及其合金在碳酸饮料中的降解机理、溶液镁离子浓度和pH值变化规律,探讨了镁合金产品作为人体补镁来源的可行性。结果表明,Mg的降解速度最快,AZ31次之,AZ91最低,表面均形成了抑制降解的(Ca,Mg)CO3腐蚀层;铝元素可有效降低镁的释放速度和碳酸饮料的pH值增幅;3种镁合金在容量为600 mL的碳酸饮料中浸泡2～4 h所释放的镁离子基本能满足每日人体所需补镁量,此时pH值变化较小,对碳酸饮料的品质无明显影响。     

Influence of pH on the deterioration of plasma electrolytic oxidation coated AM50 magnesium alloy in NaCl solutions

The corrosion deterioration process of plasma electrolytic oxidation (PEO) coatings on AM50 magnesium alloy prepared from two different based electrolytes, i.e., an alkaline phosphate electrolyte and an acidic fluozirconate electrolyte, were investigated using electrochemical impedance spectroscopy (EIS) in a 0.1 M NaCl solution with pH of 3, 7 and 11, respectively. It was found that the PEO coating formed in alkaline phosphate electrolyte, which was composed mainly of MgO, suffered from rapid chemical dissolution and lost its protection capability very quickly in acidic NaCl solution (pH 3). The chemical dissolution of this PEO coating was retarded in neutral NaCl solution (pH 7) and the corrosion damage was localized in this environment. On the other hand, in the alkaline NaCl solution (pH 11), the MgO coating underwent only slight degradation. The PEO coating produced in acidic fluozirconate electrolyte, the failure was marked by the flaking-off of the large areas of coating in acidic NaCl solution (pH 3). However, in the neutral and alkaline NaCl solutions, the coating underwent only a slight degradation without any observable corrosion damage in the 50 h test. The results showed that the deterioration process of PEO coated magnesium alloy was governed mostly by the pH of NaCl solution and it was also strongly related to the microstructure and composition of the PEO coatings.     

Research on continuous multi-point forming method for rotary surface

In order to realize high efficient and flexible manufacturing for 3-D surface, continuous multi-point forming (CMPF) is researched. Firstly, principle of CMPF is described, and its characteristics are analyzed by comparing with the conventional spinning methods. Secondly, FEA model of CMPF for disc-shape surface is established, forming load is analyzed theoretically, equivalent stress and plastic strain distributions of disc-shape surface are analyzed. Thirdly, wrinkling is analyzed through simulation results. Fourthly, forming process of tube-shape surface is studied. Finally, CMPF equipment is developed, and experiments are carried out. Results indicate: For disc-shape surface, equivalent stress in regions of center fixture and flexible roller exceeds yield stress; the maximum plastic strain is generated in center region; plastic strain in region of flexible roller takes the second place; shell elements in wrinkling region generate tangent direction compress deformation. For tube-shape surface, maximum value of equivalent stress appears in region of flexible roller; plastic strain field presents annular distribution, its maximum value appears in marginal region. Measure results of curvature radius of disc-shape surface and tube-shape surface almost accord with simulation results. Simulation results of stress field, strain field and wrinkling almost accord with practical situation.     

PHOTODEGRADATION OF p-NITROCHLORBENZENE （p-NCB） USING NANOMETER-SIZED ZnO PARTICLES PREPARED BY REACTIVE EVAPORATION METHOD

Photocatalytic degradations of p-nitrochlorbenzene (p-NCB) with distilled water were investigated with ZnO crystals (catalyst) of 70nm in diameter under UV irradiation.The suitable experimental conditions are determined as:ZnO 0.25g,pH 7,p-NCB concentration 30mg/L.These variables in terms of the degradation rate have been discussed, which was defined as the rate of the initial degradation to the final degradation of p-NCB.When all of the experimental degradation rate values are plotted as a function of irradiation time,all of the points appeared on a single line for wide range of p-NCB degradations. On the basis of these results, it has been concluded that at lower ZnO catalyst amount,much of the light is transmitted through the slurry in the container beaker, while at higher catalyst amount, all the incident photons are observed by the slurry.Degradation rates of p-NCB were found to decrease with increasing solution pH.It has been concluded that the maximum degradation rate values of p-NCB under principally the same experimental conditions mentioned above are 97.4%,98.8% and 95.5% at 100min respectively. The results suggest that the photocatalytic degradation is initiated by an oxidation of the p-NCB through ZnO surface-adsorbed hydroxyl radicals. Absorption spectra are recorded using spectrophotometer before andafter UV-irradiation in the wavelength range 200-400nm at room temperature. It is found that the variation of irradiation time over the range 20-100min resulted in change in the form of the spectrum linear absorption and a higher maximum value will be obtained at longer irradiation time.     

蛇纹石内氧化效应对铁基金属磨损表面自修复层生成的作用

高性能SiC纤维在耐高温、抗氧化领域有着重要的应用前景,而纤维直径是影响纤维力学性能的主要因素之一。随着纤维直径降低,纤维强度显著升高。利用静电纺丝工艺,结合先驱体热解转化法制备SiC,探索了一种简单、易行的制备亚微米/纳米SiC纤维的方法。由聚碳硅烷(PCS)出发,研究了PCS溶液静电纺丝的工艺参数对纺丝性的影响,PCS原纤维经不熔化、N2中1200℃热处理1h,成功的制备了纤维直径在0.5原2μm之间分布均匀的SiC纤维。