TEOS含量对有机硅/SiO_2杂化涂层性能的影响

采用溶胶-凝胶法,以正硅酸乙酯(TEOS)为无机相前驱体,甲基三乙氧基硅烷(MTES)和二苯基二甲氧基硅烷(DDS)为有机相前驱体,盐酸和水为催化剂,通过水解-缩聚反应制备了不同SiO_2含量有机硅/SiO_2有机-无机杂化溶胶.经100℃烘干12 h得到有机硅/SiO_2杂化涂层.红外光谱研究表明不同TEOS含量制备的杂化材料有机、无机两相组成了强相互作用的杂化体系.采用热重分析(TGA)和耐热性试验研究不同TEOS含量有机硅/SiO_2有机-无机杂化涂层的耐热性能;采用电化学阻抗(EIS)、浸泡试验和盐雾试验研究其耐蚀性能,结果表明与未加TEOS的有机硅涂层相比,加入适量TEOS使得杂化涂层的热分解温度提高67℃,并且其耐蚀性能也得到明显提高.     

α-ZrP/PANI电控离子交换膜对Pb~(2+)的选择性分离

采用电化学方法在水相中合成了一种新型的电活性α-磷酸锆(α-Zr P)/聚苯胺(PANI)阳离子交换材料,考察该膜在含Pb~(2+)溶液中的电控离子交换性能。分别在碳纳米管(CNTs)和PANI纳米纤维修饰的Au基体上制备了不同结构的α-ZrP/PANI杂化膜,并结合电化学石英晶体微天平(EQCM)技术,原位检测杂化膜的生长过程,分析其成膜机理。研究结果表明,在PANI纤维上制备的杂化膜因其三维多孔结构具有更高的离子交换容量;α-Zr P上的P-OH不仅能够为聚苯胺氧化还原提供氢质子,而且对Pb~(2+)表现出良好的吸附选择性,使该膜在中性含Pb~(2+)溶液中表现出良好的电活性。通过控制该杂化膜的氧化还原状态可以实现对重金属Pb~(2+)离子的选择性分离和回收。     

均匀化处理对铝-锌-镁-钪铸态合金硬度和电导率的影响

采用硬度、电导率测试、X射线衍射物相分析、扫描电子显微分析和透射电子显微分析技术,研究了不同均匀化处理条件下铝-锌-镁-钪合金组织和性能的变化规律,讨论了该铸态合金不同均匀化处理条件下显微组织结构演变与合金硬度和电导率之间的关系.结果表明,铝-锌-镁-钪铸态合金由α(Al) 基体和少量T(Mg 32(Al,Zn)49)相组成.铸态合金组织固溶体过饱和程度较高,合金硬度较高,电导率较低;随均匀化温度的升高,亚稳的过饱和固溶体先分解析出大量T相,后逐步回溶入基体固溶体中,基体固溶度先降低后增加,合金硬度先降而后升,电导率则先升而后降.更高温度下均匀化,晶粒粗化,合金硬度又下降.确定合金铸锭的理想均匀化工艺参数为470℃24 h.     

2A12铝合金表面铈盐掺杂硅烷杂化膜在3.5%NaCl溶液中耐蚀性能的电化学研究

采用溶胶-凝胶法,以γ-环氧丙氧丙基三甲氧基硅烷(γ-GPTMS)和正硅酸乙酯(TEOS)为前驱体,在2A12铝合金表面制备了稀土铈盐(Ce(NO3)3)掺杂的有机-无机杂化膜,研究了铈盐掺杂浓度和涂层固化温度等工艺条件.通过极化曲线和电化学阻抗谱(EIS),比较了掺杂与未掺杂有机-无机硅烷杂化膜、铬酸盐转化膜和RE转化膜在3.5%NaCl(质量分数)溶液中的耐腐蚀性能.测试结果均表明,铈盐掺杂硅烷杂化膜的极化电阻比掺杂前增大了约13倍,并显著高于铬酸盐转化膜和RE转化膜.     

点焊电极纳米复合材料(CuCrZr/AlN)组织性能分析

用机械合金化、粉末冶金方法制备铜铬锆合金基纳米复合材料(CuCrZr/AlN)点焊电极.采用透射电镜TEM,扫描电镜能谱SEM等方法表征纳米复合材料的组织性能.结果表明,纳米复合材料的电导率随AlN含量的增加而降低;纳米复合材料的热导率随AlN含量的增加而降低;纳米复合材料的软化温度随AlN含量的增加而提高,当AlN含量为0.4%(质量分数)时,纳米复合材料的软化温度为900℃左右;综合考虑各项性能,当AlN含量为0.2%(质量分数)时,纳米复合材料有较好的综合性能适合做点焊电极.     

溶胶-凝胶法制备AA5052系铝合金耐蚀性保护膜

采用乙烯基三乙氧基硅烷(VS)和正硅酸乙酯(TEOS)为原料,采用溶胶-凝胶法在AA5052铝合金表面制备了倍半硅氧烷(SSO)杂化膜。采用动电位极化法和电化学阻抗法测试了膜层的耐腐蚀性能,并考察了正硅酸乙酯的含量对其膜层的影响。结果表明,杂化膜能有效抑制AA5052铝合金的腐蚀反应,且当正硅酸乙酯的含量为20%时,杂化膜涂层的耐腐蚀性最好。     

DDS含量对有机硅/SiO_2杂化涂层性能的影响

采用溶胶-凝胶法,以正硅酸乙酯(TEOS)为无机相前驱体,甲基三乙氧基硅烷(MTES)和二苯基二甲氧基硅烷(DDS)为有机相前驱体,盐酸和水为催化剂,通过水解-缩聚反应制备了不同DDS含量的有机硅/SiO_2有机-无机杂化溶胶。在100℃下经12 h烘干得到有机硅/SiO_2杂化涂层。涂层性能测试表明:随DDS含量增加,硬度、附着力、耐蚀性(未加DDS耐蚀性较差)有所下降;柔韧性均为1级。低温下涂层耐热性较好。溶胶中n(TEOS):n(MTES):n(DDS)为6:9:2时涂层综合性能最佳。     

The electrochemical study of corrosion resistance of silane-based hybrid films doped with rare earth salt on aluminum alloy

采用溶胶-凝胶法, 以γ-环氧丙氧丙基三甲氧基硅烷(γ-GPTMS)和正硅酸乙酯 (TEOS)为前驱体, 在2A12铝合金表面制备了稀土铈盐(Ce(NO3)3)掺杂的有机－无机杂化膜, 研究了铈盐掺杂浓度和涂层固化温度等工艺条件. 通过极化曲线和电化学阻抗谱(EIS), 比较了掺杂与未掺杂有机－无机硅烷杂化膜、铬酸盐转化膜和RE转化膜在3.5%NaCl (质量分数)溶液中的耐腐蚀性能. 测试结果均表明, 铈盐掺杂硅烷杂化膜的极化电阻比掺杂前增大了约13倍,并显著高于铬酸盐转化膜和RE转化膜.     

铈盐掺杂GPTMS/TEOS硅烷杂化膜腐蚀电化学行为随时间的变化

以γ-环氧丙氧丙基三甲氧基硅烷(GPTMS)和正硅酸乙酯(TEOS)为前躯体,采用溶胶-凝胶法在LY12铝合金基体表面制备了铈盐Ce(NO3)3掺杂有机-无机杂化膜。通过极化曲线与电化学阻抗谱(EIS)研究铈盐掺杂硅烷杂化膜在3.5%(质量分数)NaCl溶液中耐蚀性能随浸泡时间的变化。结果表明,硅烷杂化膜的极化阻抗值随浸泡时间延长而缓慢降低,但浸泡183 h后仍显著高于金属基体;铝合金点蚀电位在浸泡期间呈现先降低后升高再降低的变化。在浸泡初期,EIS曲线的高频容抗行为显著。从69 h至260 h浸泡试验结束,低频阻抗值保持基本稳定。上述变化与膜中掺杂的铈盐具有自修复性质密切相关。     

稀土元素Gd对Co/Pt多层膜居里温度的影响

采用镶嵌靶法制备添加稀土元素Gd的Co／Pt多层膜，以θk＝0和铁磁性消失的温度表征居里温度(Tc)。研究结果表明：添加适量Gd于Co／Pt多层膜中，其Tc＜200℃；在本工作研究的成分范围内，Tc随Gd含量增加而降低。运用分子场理论讨论了Tc与交换作用的关系，并根据s—f电子交换模型探讨了添加稀土元素降低Co/Pt多层膜Tc的机理。     

Structural, mechanical and corrosion properties of TiOxNy/ZrOxNy multilayer coatings

Results on the deposition and characterization of TiO_xN_y/ZrO_xN_y multilayers, with bilayer periods of 20 and 400 nm, are presented. The coatings were deposited on TiNiNb alloy substrates by the pulsed magnetron sputtering method. The elemental composition, hardness, adhesion and corrosion resistance of the coatings were analyzed.As resulted from the XPS analysis, the individual layers consisted of a mixture of titanium or zirconium oxynitrides and corresponding oxides. X-ray analysis revealed that the coatings were amorphous. Only slight differences between the microhardness and adhesion values of the coatings with small and large bilayer period Λ were found. The experiments also showed that the multilayered coatings improved the corrosion resistance of the uncoated alloy and reduced the amount of ion release in artificial body fluids.     

生物医用NiTi形状记忆合金腐蚀研究进展

镍钛形状记忆合金(NiTi-SMA)具有较好的耐腐蚀和机械性能,在口腔和临床医学中有着大量而广泛的应用。NiTi-SMA腐蚀后释放Ni²⁺会引发细胞毒性和过敏反应,进一步提高NiTi-SMA的耐蚀性是目前生物医学材料领域发展的核心之一。本文对近年来国内外有关口腔医学和临床医学中常用NiTi-SMA的腐蚀研究现状进行了总结,同时也对NiTi-SMA增材制造及表面改性技术进行了评述,以期为开发高性能抗腐蚀生物医用NiTi-SMA提供一定的指导意义。     

Li掺杂Ba(Ti1/7Sn1/7Zr1/7Hf1/7Nb1/7Ga1/7Li(1/7-x))O3高熵陶瓷的制备及介电性能研究

近年来,在高熵合金基础上发展起来的高熵陶瓷逐渐引起了研究者的广泛关注,其出现为开发高性能的无机非金属材料提供了新的设计思路。本文采用固相法制备了BaMO3基钙钛矿型高熵陶瓷Ba(Ti1/7Sn1/7Zr1/7Hf1/7Nb1/7Ga1/7Li(1/7-x))O3 (x = 0, 2.3%, 5.3%, 8.3%, 11.3%),并研究了Li含量对高熵陶瓷物相结构、微观形貌及介电性能的影响。结果表明,Li含量对陶瓷结构的影响不大,陶瓷均保持立方钙钛矿结构,且无杂相产生;陶瓷的晶粒尺寸相对较均匀。当x = 0时,即B位七元等摩尔比Ba(Ti1/7Sn1/7Zr1/7Hf1/7Nb1/7Ga1/7Li1/7)O3高熵陶瓷,其介电常数达到了最大值2920 (@100 Hz),相较于已报道的不掺Li的六元高熵钙钛矿陶瓷Ba(Ti1/6Sn1/6Zr1/6Hf1/6Nb1/6Ga1/6)O3提升了近50倍。     

MOCVD growth and characterizations of BxAl1−xAs and BxAl1−x−yInyAs alloys

Zinc-blende B_xAl_1−xAs and B_xAl_1−x−yIn_yAs alloys have been grown on exactly oriented (0 0 1)GaAs substrates by low pressure metalorganic chemical vapor deposition (LP-MOCVD). The influence of susceptor coating, growth temperature and gas-phase boron mole fraction on boron incorporation into AlAs has been comprehensively investigated. It has been found that boron incorporation into AlAs could be enhanced and the optimal growth temperature range of B_xAl_1−xAs alloys changed from 580 °C to 610 °C when SiC-coated graphite susceptors were replaced by the non-coated ones. In this study, the maximum boron composition x of 2.8% was achieved for the pseudomorphically strained B_xAl_1−xAs alloys. AFM measurements show that RMS roughness of B_xAl_1−xAs alloys increased sharply with the increase of gas-phase boron mole fraction. Raman spectra of B_xAl_1−xAs alloys show a linear increase of the BAs shift with boron composition x. Based on BAlAs deposition, bulk B_xAl_1−x−yIn_yAs (x = 1.9%) quaternary alloy was grown lattice-matched to GaAs successfully. Moreover, 10-period BAlAs/GaAs and BAlInAs/GaAs MQW heterostructures were also demonstrated.     

Hydrothermal synthesis of superconductors Ba1−xKxBiO3 and double perovskites Ba1−xKxBi1−yNayO3

Superconductors Ba_1−xK_xBiO₃ and body-centered double perovskites Ba_1−xK_xBi_1−yNa_yO₃ have been selectively synthesized by a facile hydrothermal route. The appropriate ratio and adding sequence of initial reagents, alkalinity, reaction temperature and time are the critical factors that influence the crystal growth of the compounds. The purity and homogeneity of the crystals were detected by the ICP, SEM, EDX and TEM studies. Magnetic measurements show that the superconducting transition temperatures T_C of Ba_1−xK_xBiO₃ decrease from 22 K (for x = 0.35) to 8 K (for x = 0.55) with increasing the K doping level.     

Magnetic phase diagrams of the TbRh2−xPdxPdxSi2 and TbRu2−xPdxSi2 systems

The a.c. susceptibility and high field magnetization on TbRh_2−xPd_xPd_xSi₂ and TbRu_2−xPd_xSi₂ compounds were investigated up to 140 kOe. The (T,x) magnetic phase diagrams were determined. For both systems, an increase in the Pd content causes a decrease in the Néel temperature and changes the magnetization curves.     

High strength and good ductility of casting Al-Cu alloy modified by PrxOy and LaxOy

A modified Al-Cu alloy with high tensile strength and ductility of about 574.0 MPa and 10.4%, respectively, was obtained by adding multiple rare earth oxides (Pr_xO_y and La_xO_y) as modifier. Compared with the unmodified Al-Cu alloy, the tensile strength and ductility of the modified sample were increased by 24.3% and 42.5%, respectively. The improvement both in the strength and ductility may attribute to the finer crystal grains and dendrites, more homogeneously distributed θ′ phase precipitates and the intermetallic compounds formed at the crystal grain boundaries as well as in the space of the dendrites.     

Si3N4/Ti/Cu/Ni/Cu/Ti/Si3N4二次部分瞬间液相连接强度

采用Ti/Cu／Ni中间层对Si3N4陶瓷进行二次部分瞬间液相(PTLP)连接，研究连接工艺参数对Si3N4／Ti/Cu／Ni连接强度的影响，同时研究了连接强度随试验温度的变化规律。结果表明，在该试验条件下，室温连接强度随着二次连接温度的提高和二次保温时间的延长而提高，改变连接工艺参数对Si3N4／Ti/Cu／Ni二次PTLP连接界面反应层厚度无明显影响；连接强度在试验温度400℃时达到最大，随后随试验温度升高，连接强度降低，但在800℃前，其高温强度具有很好的稳定性。     

Structural analysis of sputtered (W-C)1−xMx (MFe, Co) films with 0x0.20

Structural characterization of (W-C)_1-xM_x (MFe, Co) films with 0x0.20 was carried out using electron probe microanal ysis (EPMA), X-ray diffraction (XRD) and transmission electron microscopy-electron diffraction (TEM-ED). The results showed that the structure of these films depends on the percentage of iron and cobalt and becomes amorphous with increasing content of these elements. The microstructure of the crystalline coatings was found to be composed of small grains of β-WC_1-x with a high number of defects. A strong β-WC_1-x[311] texture was observed for iron and cobalt contents around 5.5 at.%. The films richer in iron and cobalt showed typical amorphous XRD and ED patterns, exhibiting two broad peaks and two wide diffuse rings respectively. Moreover, bright-field analysis revealed fairly contrasted images, the structure of these films being difficult to resolve.