Hydroxyapatite-containing PEO-coating design for biodegradable Mg-0.8Ca alloy: Formation and corrosion behaviour

In this study, the biocompatible protective coating was formed using plasma electrolytic oxidation(PEO) on bioresorbable Mg-0.8Ca alloy. The composition of the formed coating was studied using XRD, SEM-EDX analysis, and micro-Raman spectroscopy. The uniform distribution of hydroxyapatite over the thickness of protective PEO-layer was established. Using traditional(EIS, PDP, OCP) and local scanning electrochemical methods(SVET, SIET with H^(+)-selective microelectrode), the level of protective properties of PEO-layer in a biological environment(mammalian cell culture medium, MEM) was determined. It was established that modification of Mg-0.8Ca alloy surface by PEO contributes to a significant increase in the corrosion resistance of the surface layer, making it possible to control the process of material‘s biodegradation. The maximum local electrochemical activity was recorded after 72 h of testing, while for the uncoated sample,intense corrosion degradation was recorded in the first 12 min of exposure to the cell culture medium. Formation of the PEO-coating results in a twofold decrease in the corrosion current density(2.8·10^(-6)A cm^(-2)) and an increase in the impedance modulus measured at a low frequency(1.7·10^(4)Ω cm^(2)) in comparison with the uncoated material(9.5·10^(-6)A cm^(-2);8.1·10^(3)Ω cm^(2)). The mechanism of material bioresorption was established and a model for biodegradation process of Mg-0.8Ca alloy with hydroxyapatite-containing PEO-coating in MEM was proposed. Analysis of these results and comparing with others obtained by various scientific groups indicate the prospects for application of biocompatible PEO-coating on Mg-Ca alloy in implant surgery.

钛合金在油气开采中的应用及研究现状

我国目前现有的油井管用钛合金都是在其他行业所用钛合金的基础上进行改进设计的,普遍存在抗腐蚀性能较差、成本较高等缺点,并且钛合金在我国油气开采领域还未得到大规模的生产与应用。总结了钛合金油井管在油气开采领域的应用以及油井管用钛合金抗腐蚀能力的研究成果,并且梳理了我国目前油井管用钛合金材料抗腐蚀性能的不足,为后续的研究提供参考。

基于空洞卷积神经网络的铝硅合金实体关系联合抽取模型(英文)

近年来,材料基因组计划(Material genome initiative,MGI)已经成为全球热点。随着材料科学的不断发展,材料文献中包含的海量信息成为研究人员关注的焦点,如何获取大量有效的材料数据是现阶段的主要挑战。本文采用自然语言处理(Natural language processing,NLP)技术从铝硅合金材料文献中获取数据。命名实体识别(Named entity recognition,NER)和关系抽取(Relation extraction,RE)是NLP的两个子任务,可以高效地从文本中提取单词信息及其之间的关系。铝硅合金文献中存在多种命名实体及多种关系,本文从材料科学文献中选择11种实体类型和13种关系类型,手动标注构建了铝硅合金实体关系数据集,将命名实体识别与关系抽取进行联合学习,即对实体识别和关系抽取进行统一建模。此外,针对基础模型的编码层存在捕捉文本语义信息不充分问题,通过改进模型的编码层,将基础模型的BiLSTM层与空洞卷积模型结合,组成了新的编码器,避免了BiLSTM处理文本信息丢失的问题,最终使铝硅合金实体关系联合抽取模型能够更好地捕捉文本中句子的语义单元信息。

The detailed corrosion performance of bioresorbable Mg-0.8Ca alloy in physiological solutions

The electrochemical behaviour of biodegradable magnesium alloy Mg-0.8Ca was evaluated in a mammalian cell culture medium(MEM)and Na Cl solutions(0.9 wt.%, 0.3 wt.%) using traditional(EIS, PDP, OCP) and local scanning electrochemical(SVET, SIET with p H-selective microelectrode) methods at the micro-and meso-level. Corrosion rates of samples in two different media were determined using weight loss tests. The influence of testing media components, alloy composition and microstructure on the material’s degradation process was determined.The SVET/SIET test parameters were optimized for in vitro investigation of the bioresorbable material surface. The mechanism of the alloy’s bioresorption was suggested. The effect of microsized phases on the corrosion behaviour of the alloy was proved using complementary in situ monitoring and SKPFM measurements. The rapid degradation rate of the alloy is related to the presence of local microgalvanic cells formed by cathodic α-magnesium matrix and anodic Mg_(2)Ca phase. The highest corrosion activity was revealed in the first 12 min of sample exposure to MEM, followed by stabilization of corrosion process due to the material’s passivation. Using SEM-EDX analysis, micro-Raman spectroscopy and XPS analysis the composition of the corrosion products was determined. Degradation in MEM proceeds with a formation of magnesium-and-carbonate substituted hydroxyapatite-containing film on the sample’s surface. The low possibility of application of Mg-0.8Ca alloy without coating protection in implant surgery was highlighted.

Separation of primary solid phases from Al-Si alloy melts

The iron-rich solids formed during solidification of Al-Si alloys which are known to be detrimental to the mechanical,physical and chemical properties of the alloys should be removed.On the other hand,Al-Si hypereutectic alloys are used to extract the pure primary silicon which is suitable for photovoltaic cells in the solvent refining process.One of the important issues in iron removal and in solvent refining is the effective separation of the crystallized solids from the Al-Si alloy melts.This paper describes the separation methods of the primary solids from Al-Si alloy melts such as sedimentation,draining,filtration,electromagnetic separation and centrifugal separation,focused on the iron removal and on the separation of silicon in the solvent refining process.

Tunable surface plasmon-polariton resonance in organic light-emitting devices based on corrugated alloy electrodes

We report a feasible method to realize tun able surface plasm on-polarit on(SPP)res onance in orga nic light-emitt ing devices(OLEDs)by emplo ying corrugated Ag-Al alloy electrodes.The excited SPP res onance in duced by the periodic corrugations can be precisely tuned based on the composition ratios of the Ag-Al alloy electrodes.With an appropriate composition ratio of the corrugated alloy electrode,the photons trapped in SPP modes are recovered and extracted effectively.The 25%in creaseme nt in luminance and 21%enhan ceme nt in curre nt efficie ncy have bee n achieved by using the corrugated Ag-Al alloy electrodes in OLEDs.

Niobium Extraction from Baotou Iron Ore Containing Niobium

The experimental results of niobium enrichment in laboratory and in blast furnace in Baotou Iron and Steel Corporation were reported.The effects of temperature,constituents of slag and silicon content in hot metal on niobium recovery were studied and the results have been verified by blast furnace operation.Optical and electronic microscopy and EPMA was observed that at the metal-slag interface there is NbC deposit layer obstructed Nb entering into the metal,By raising the temperature of hearth and agitating the bath,the reduc- tion of niobium oxide in slag could be speeded up,the solubility of Nb in hot metal could increase and the deposited NbC layer became thinner and even disappeared,in result,Nb recovery was increased.A compre- hensive extraction process combining ore dressing with pyro-hydro-metallurgy was suggested for Baotou niobium resource which was difficult to be concentrated formerly.The methods of increasing niobium recovery were also suggested.

The Inhibition Effect of Cinnamon Extract on Leaching of Aluminum Cook Wares in NaCl Solutions at Quasi-Cooking Condition

The contribution of cinnamon extract on leaching of aluminum (Al) cook wares was investigated using two aluminum alloys (Indian and Egyptian) and pure Al. The cinnamon (Cin) was extracted by heating the Cin sticks at 90&degC in distilled water for an hour to make the 10% stock solution. This study was done in aqueous solutions in presence and absence of 1% NaCl using weight loss at 90&degC. Moreover surface study (SEM and EDX) and electrochemical methods (Open Circuit Potential and Tafel plot) were applied. The addition of Cin solutions to 1% NaCl decreased the corrosion rates in weight loss and electrochemical method compared to 1% NaCl solutions which showed an inhibitive property of Cin solution. The inhibition was found to obey the modified Langmuir isotherm with a negative Langmuir ΔGads indicating the spontaneous nature of adsorption even at 90&degC. The EDX surface analysis of the Al surface immersed in Cin + NaCl revealed the composition of the pits formed. From Tafel method, it was found that the corrosion current density of pure Al was more than that of the Egyptian alloy. The apparent activation energy values for Cin, Cin + NaCl and NaCl solution were evaluated and discussed.

Superelasticity of Cu–Ni–Al shape-memory fibers prepared by melt extraction technique

In the paper, a melt extraction method was used to fabricate Cu–4Ni–14Al（wt%） fiber materials with diameters between 50 and 200 μm. The fibers exhibited superelasticity and temperature-induced martensitic transformation. The microstructures and superelasticity behavior of the fibers were studied via scanning electron microscopy（SEM） and a dynamic mechanical analyzer（DMA）, respectively. Appropriate heat treatment further improves the plasticity of Cu-based alloys. The serration behavior observed during the loading process is due to the multiple martensite phase transformation.

基于合金注入与大视域图像技术的致密储层孔隙与喉道表征

致密油气是我国油气资源的重要组成部分,对其孔喉结构的研究有利于推进致密油气地质理论的丰富和完善。以鄂尔多斯盆地三叠系延长组致密储层为例,通过高温高压合金注入装置,结合大视域图像拼接技术与图像孔隙提取方法,建立了致密储层孔隙结构表征新方法。结果表明,将合金注入致密储层孔隙中可以较好地反映孔隙连通性特征,使孔隙形貌和结构更加容易辨别。大视域图像拼接方法解决了孔隙分布非均质性强、小视域观察代表性差的问题。鄂尔多斯盆地延长组致密储层主要发育粒间孔、粒内孔和粒间—粒内混合孔,其中粒间孔最为发育。孔隙缩小型喉道、缩颈型喉道、管束型喉道、片状喉道和弯片状喉道是其发育的5种喉道类型,其中弯片状喉道最为发育。石英和长石的孔隙明显大于其他矿物孔隙,对致密储层面孔率的贡献率达74%,是致密油气重要的赋存空间。

镁合金活性TIG焊焊接接头组织特征分析

对活性化焊接 (A -TIG)方法在镁合金焊接中的应用进行了初步的探讨。选取TiO2 作为活性剂 ,研究了单一活性剂TiO2 对镁合金焊接后微观组织的影响。试验结果表明 ,涂敷单一活性剂TiO2 可以使焊缝熔深比常规的TIG焊增加 2倍。与未涂敷活性剂的焊缝相比 ,涂敷TiO2 活性剂可以增大焊接的熔深 ,减小熔宽。

高导磁非晶合金纤维的研制

在充分研究了现有制造非晶合金条带的工艺设备以及市场发展前景的基础上,改造了现有条带设备,成功地研制出高导磁非晶合金纤维.用熔融拉丝法(MeltExtraction)制成直径在10～100μm范围内的合金纤维,研究表明此种材料具有典型的非晶特性,优越的软磁特性,更具有体积小、隐蔽性强、成本低等特点,是一种值得推广、并具有广泛市场潜力的材料.

钴白合金湿法冶金工艺研究

本文研究了钴白合金湿法冶炼工艺流程，详细进行了氯气浸出－电溶脱铜－ＴＢＰ萃取除铁试验研究。试验条件下，钴、铜、铁浸出率均达到９９％，且分离效果良好。文章给出了钴白合金冶炼原则工艺流程。

铝合金7050-T7451高温高应变率本构方程及修正

通过分离式霍普金森压杆(SHPB)及准静态压缩实验研究铝合金7050-T7451高温高应变率下流变应力特征,利用准静态实验数据获得本构方程应变强化参数,利用SHPB实验数据获得室温下不同应变率(400～2500s-1)的应变率强化参数,以及应变率为2500s-1不同温度下(250～600℃)的热软化参数。利用不同幂次多项式对Johnson-Cook本构方程的热软化项拟合,最终选择五次多项式作为修正后本构方程热软化项。利用修正后本构方程对不同温度条件下应力-应变曲线进行预测,实验数据与预测曲线表现出良好一致性。

旋转喷嘴鼓泡法提取液态锂铅合金中的氢

模拟了锂铅合金中氚提取技术,在采用流体力学建立代数模型的基础上,开展了旋转喷嘴鼓泡法提取锂铅合金中氢的研究。研究结果表明:锂铅熔融温度越高,氢提取累计效率越高;鼓泡床气含率受叶轮孔径影响不大,只是在较高的氦气流速下,采用小孔径时的气含率略高于大孔径,但孔径越小,气泡比表面积越大;随着氦气流速的增加,液态锂铅流循环强度明显增加,氢提取速率加快;喷头转速对氢提取影响有限。

基于优化最小二乘支持向量机的小样本预测研究

统计学中的预测问题主要是通过对已知数据的分析,找到数据内在的相互依赖关系,从而获得对未知数据的预测能力。该文提出了最小二乘支持向量机参数优化方法———多层动态自适应优化算法,构建了基于最小二乘支持向量机的预测模型,并对Ti 26合金的性能预测进行了研究。结果表明:优化的最小二乘支持向量机具有优秀的小样本数据学习能力和预测能力。

铝合金MIG焊熔池图像的形态学处理方法

建立了用于铝合金脉冲MIG焊熔池图像检测的CCD视觉系统,通过窄带滤光系统和选取合适的焊接规范,获取了铝合金脉冲MIG焊熔池的清晰图像。分析了铝合金焊接熔池图像的特征。针对目前已有熔池图像处理算法的缺点,利用形态学方法去除了图像信号中的噪声、阴极雾化区等影响熔池特征提取的部分,获得了满意的熔池边缘图像,为进一步实现铝合金MIG焊接过程控制创造了条件。

萃取分离-石墨炉原子吸收光谱法测定铁镍基高温合金中砷、铅、锡、锑、铋

基于砷、铅、锡、锑、铋与碘离子形成络合物，用MIBK萃取使其与基体分离，用石墨炉原子吸收光谱法测定了铁镍基高温合金中这五种元素。文章主要对萃取条件及萃取后剩余基体对待测元素的影响进行了研究，同时采用掩蔽的方法消除了合金中钨、铌、钽的干扰。在所选定的实验条件下，测得砷、铅、锡、锑、铋的回收率范围为93％～99％；相对标准偏差范围为8．8％～12％。

浊点萃取-分光光度法测定铝合金中痕量镍的研究

在pH9.5的Na2B4O7-NaOH缓冲溶液中和非离子表面活性剂Triton X-114存在下,1-(4-硝基苯基)-3-(5,6-二甲基-1,2,4三氮唑)-三氮烯(NPDMTT)与Ni 2+生成的络合物被萃取到表面活性剂Triton X-114中,经离心分相后,以475nm和540nm为测定波长,采用分光光度法对表面活性剂富集相中镍进行测定。实验结果表明,表面活性剂富集相用乙醇(1∶2)稀释后,测得络合物的表观摩尔吸光系数为7.293×105L.mol-1.cm-1,校准曲线的线性范围为0～0.14μg/mL,相关系数为0.999 3。建立的方法用于铝合金样品中镍的测定,测定结果与参考值相符,6次测定结果的相对标准偏差小于3%。

铝合金点焊过程中影响因素的特征判识与熔核尺寸的评估

铝合金电阻点焊过程中,各种影响焊接质量的因素,既相互耦合,又表现出各自的特征。利用研制的一套点焊过程参数采集与显示系统,对这些影响因素的特征信息进行提取和分析。并在此基础上,应用模糊数学理论,建立了铝合金焊点质量在线监测系统,借助该系统不仅可以评估熔核尺寸,并且可以判识导致熔核尺寸发生波动的可能原因;如若发生喷溅,该系统可以判识喷溅的强度、喷溅发生的时刻以及引发喷溅的可能原因。