Surface modification with SiO_2 coating on biomedical TiNi shape memory alloy by sol-gel method

The effect of heat treatment on the transformation temperature of Ti?52.2%Ni (mole fraction) alloy was studied using differential scanning calorimetry (DSC). The transformation temperatures of the alloy can be adjusted effectively by heat treatment. Dense and stable SiO2 coatings were deposited on the surface of the pre-oxidized TiNi alloy by sol?gel method. The bonding strength of films and matrix was (65.9±1.5) N. The electrochemical corrosion test shows that the TiNi alloy with SiO2 coating has excellent corrosion resistance in the Hank’s simulated body fluid. The release behaviors of Ni ion of the alloy with and without SiO2 coating implanted in the acoustic vesicle of guinea pig were studied by EDS testing, which was inhibited effectively by the dense and stable SiO2 coating on the alloy.

Crystalline texture evolution, control of the tribocorrosion behavior, and significant enhancement of the abrasion properties of a Ni-P nanocomposite coating enhanced by zirconia nanoparticles

This paper describes an investigation of the effect of ZrO2 nanoparticles on the abrasive properties,crystalline texture developments,and tribocorrosion behavior of Ni-P nanostructured coatings.In the investigation,Ni-P and Ni-P-ZrO2 nanostructured coatings are deposited on St52 steel via the electroless method.Transmission electron microscopy(TEM),field emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD),energy dispersive spectroscopy(EDS),cyclic-static polarization tests in 3.5wt%NaCl solution,the tribocorrosion test(by back-and-forth wear in electrochemical cell),and the microhardness test using the Vickers method were performed to characterize and analyze the deposited coatings.The results of this study showed that the addition of ZrO2 nanoparticles to the Ni-P electroless bath produced the following:a sharp increase in wear and hardness resistance,the change of the wear mechanism from sheet to adhesive mode,the reduction of pitting corrosion resistance,significant reduction in the tribocorrosion protective properties,change in the preferred orientation of the crystalline texture coating from(111)to(200),increase in the sedimentation rate during the deposit process,and a sharp increase in the thickness of the Ni-P nanostructured coatings.

Kinetic Study of SiO_2/S Coating Deposition by APCVD

To alleviate catalytic coking on the inner surface of radiant tube for ethylene production in petrochemical plants,SiO2/S coatings were deposited on HP40 alloy specimens using dimethyldisulfide （DMDS） and tetraethoxysilane （TEOS） by atmospheric pressure chemical vapor deposition （APCVD）. A two-dimension mathematical model was made to predict the growth rate of SiO2/S coating and to study the effects of deposition parameters on the deposition rate. The results show that the predicted deposition rate is in good agreement with the experimental one. The deposition rate mainly depends on the concentrations of precursors in the total gas flow, concentrations of intermediates on the deposition surface, total gas flow rate and deposition temperature. The weight of SiO2/S coating linearly increases with the deposition time. When the gas flow rate is below 0.3 m/s, the rate-limiting step of SiO2/S coating deposition is the diffusions of intermediates.However, the surface reactions of intermediates will be the rate-limiting step after the gas flow rate is above 0.3 m/s. When the deposition temperature is below 780℃, the rate-limiting step of SiO2/S coating deposition mainly depends on the surface reactions of intermediates. When the deposition temperature is above 780℃,the rate-limiting step depends on the diffusions of intermediates. The deposition rate increases with increasing the concentrations of the intermediates. However, when the partial pressures of the intermediates reach 8 Pa,the deposition rate keeps constant.

Fabrication and Microstructure of SiO_2-GeO_2 Sol-gel Glass Coatings

SiO 2-GeO 2 sols and gel glass coatings with different contents of germanium dioxide were fabricated.Stable and transparent sols could only be obtained when the content of GeO 2 was under 35%.It is shown by SEM that only one continuous phase is observed in the coating of 65SiO 2·35GeO 2 and plenty of Ge,O and Si were all found in it.However,the separated phase is found in the coating of 60SiO 2·40GeO 2 and a large number of Ge and O.It is proved by the Raman scattering investigation that the separated phase in the coating of 60SiO 2·40GeO 2 is germanium dioxide.The congeries of hydrolystates of Cl 3GeCH 2CH 2COOH play the main role in the formation of the separated phase when the proportion of GeO 2 is much higher.Si-O-Ge,Si-O-Si,and Ge-O-Ge bonds form in the coating of 65SiO 2·35GeO 2 and this coating is homogenous.

Influence of heat treatment on microstructures and micro-hardness of n-SiO2/Ni composite coating

The n-SiO2/Ni composite electro-brush plating coating was prepared on the 1045 steel substrate. SEM and TEM were utilized to analyze the surface and cross-section morphologies or the microstructures of the composite coating before and after heat treatment, as well as a micro-hardness tester was used to measure the micro-hardness before and after heat treatment. The results show that the entrance of nano SiO2 particles into composite coating makes the micro-hardness higher. After heat treatment, due to the obstruction to growth of Ni crystals from nano particles, the composite coating still possesses a higher micro-hardness than that of common Ni-base coating.

Application of Nano Coating （SiO2） on Textile Products

Liquid SiO2 solutions produced by silicon-based nano- powder are covered on the fabric surface by using spray method. Fabric surfaces were coated at the room temperature in air with the different spray nozzles. Surface analysis of the coated fabric was performed by using Contact Angle and SEM pictures. According to the Contact Angles measurements, the coated fabric surfaces showed hydrophobic character between 126 and 146 degrees, and the SiO2 particles sticked to the fabric fibers as seen from SEM picture.

施镀条件和热处理对铝合金Ni-P-SiO_2复合镀层微观结构及显微硬度的影响

目的提高Ni-P镀层的硬度。方法在化学镀Ni-P过程中添加SiO2微粒,形成Ni-P-SiO2复合镀层,研究施镀温度、微粒添加量和镀后热处理温度对复合镀层微观结构及硬度的影响。结果复合镀层含非晶结构Ni和SiO2相。随施镀温度的升高及SiO2微粒添加量的增加,镀层表面变得均匀、致密且硬度升高,显微硬度最高达355HV;当施镀温度超过80℃,微粒添加量超过10 g/L时,镀层表面均匀性变差,硬度下降。经热处理后,镀层向晶态转变,热处理温度达到300℃时开始析出Ni3P相,镀层的显微硬度随热处理温度的升高而升高。结论当施镀温度为80℃、微粒添加量为10 g/L时,所得复合镀层的性能较为优异,热处理可进一步提高复合镀层的硬度。

脉冲复合电镀(Ni-P)-纳米微粒SiO_2工艺

采用脉冲电流,制备(Ni-P)-纳米SiO2复合镀层。通过正交试验设计的方法,重点考察了脉冲平均电流密度、脉宽、占空比、搅拌方式及纳米SiO2的添加量对镀层沉积速率、镀层硬度以及镀层中SiO2质量分数的影响,从而遴选出最佳的电镀工艺。同时,对脉冲电镀与直流电镀进行了比较。

Microstructure and depositional mechanism of Ni-P coatings with nano-ceria particles by pulse electrodeposition

Nano-CeO2 （RE） particles were co-deposited into Ni-P binary composite coatings by applying pulse current （PC） under ultrasonic （U） field. Morphology, chemical content and crystal microstructure were characterized by environmental scanning electron microscopy （E-SEM） with energy dispersive X-ray analysis （EDXA）, XRD diffractometry and transmission electron microscopy （TEM）. Experimental results show that Ni-P coating reinforced with 15g/L nano-CeO2, in amorphous state and with compact structure, can be improved in the microhardness from HV0.2580 to HV0.2780 by annealing at 600 °C for 2 h. The highest content of codeposited Ce and deposition rate can reach 2.3% and 68 μm/h, respectively. Furthermore, the effect of RE adsorption and pulse overpotential on depositional mechanism was investigated. n-CeO2 particles or Ce4＋ ions with strong adsorption capacity acted as the catalytic nucleus to improve densification effectively. During annealing at 600 °C for 2 h, n-CeO2 particles will uniformly adsorb on crystal grain to preferentially pad and heal up gaps of cracking Ni boundaries, promoting dispersion strengthening with refiner-grained structure.

镀液组成对刷镀(Ni-P)-SiO_2工艺的影响

研究了 (Ni P) SiO2 刷镀液中Ni2 + 离子、NaH2 PO2 、SiO2 微粒、金属盐的比例、温度等因素对刷镀 (Ni P) SiO2 工艺的影响。结果表明 ,在刷镀 (Ni P) SiO2 工艺中 ,选择适当刷镀液组成 ,刷镀层沉积速率和镀层质量明显提高 ,并由此得出了刷镀(Ni P) SiO2

(Ni-P)-SiO_2化学复合镀液中分散剂的研究

在铜表面上的（Ni-P）-SiO2化学复合镀中,将Al2（SO4）、CoSO4和CrCl3作为纳米SiO2分散剂添加到镀液中.由分光光度计测定发现少量金属盐对纳米SiO2粒子在镀液中的分散稳定性均有一定程度提高.通过光电子能谱检测发现,Al2（SO4）3作为纳米SiO2分散剂的（Ni-P）-SiO2化学复合镀层中纳米SiO2沉积效果优于其他分散剂.0～8nm深度刻蚀检测表明镀层中纳米SiO2质量分数稳定.实验表明,以Al2（SO4）3作为分散剂最佳质量浓度为3.06～ 4.08 g/L.

溶胶增强的化学Ni-P-SiO_2复合镀层

采用在基础Ni-P镀液中直接加入溶胶SiO_2的新形式,结合溶胶-凝胶法和化学镀方法,于45钢基材表面成功制备了均匀的复合Ni-P-SiO_2镀层,对比研究了复合镀层与基础Ni-P镀层的显微组织结构、耐磨及耐腐蚀性。结果表明,加入溶胶SiO_2所制备的复合镀层较Ni-P镀层具有更加均匀、致密的显微形貌。当SiO_2溶胶加入量为2.1×10^(-3) mol/L、煅烧温度为400℃时,复合镀层具有最高显微硬度值668.54 HV_(0.025),最低摩擦系数0.279,最正腐蚀电位-0.449 7 V及最小腐蚀电流0.632 7×10^(-6) A·cm^(-2)。说明以该方法所制备的复合Ni-P-SiO_2镀层具有良好的耐磨、耐腐蚀性能,节省SiO_2原料用量,且不需要额外加入分散剂与稳定剂,减少长时间搅拌的能耗,对实际工业生产大有裨益。

纳米SiO_2对汽车用铝硅镁系合金化学镀Ni-P合金镀层性能的影响

以汽车用铝硅镁系合金(牌号ZAlSi7MgA)为基体,采用化学镀方法制备了Ni-P合金镀层和Ni-P/SiO_2复合镀层。采用扫描电镜、X射线能谱仪和电化学工作站等仪器,研究了纳米SiO_2对Ni-P合金镀层的表面形貌、物相组成、硬度、耐磨性及耐蚀性的影响。结果表明:与Ni-P合金镀层相比,Ni-P/SiO_2复合镀层具有更好的性能。这与纳米SiO_2对Ni-P合金镀层起到的强化作用有关。铝硅镁系合金化学镀Ni-P/SiO_2复合镀层后,其硬度提高5倍以上,耐磨性和耐蚀性也都得到提高,磨损速率明显降低,电荷转移电阻升高。

Luminescent Properties of BaMgAl_(10)O_(17)∶Eu^(2+) Phosphors Coated with Y_2SiO_5

BaMgAl10O17： Eu^2＋ phosphors was prepared by the solid-reaction method. Y2SiO5 was coated uniformly on the surface of phosphor by the surface-coated method, and the luminescent and deterioration properties were discussed. The XRD and SEM results show that Y2SiO5 film is produced on the surface of BAM phosphor. The emission spectrum analysis shows that the peak of the phosphor does not change after coating. The two phosphors were applied to lamps and the deterioration was tested at different ignited time. The keep ratio of luminous flux of the phosphor coated with Y2SiO5 is higher than that of the uncoated phosphor.

纳米TiO_2表面包覆致密SiO_2膜的试验研究

用液相沉积法对纳米二氧化钛进行了表面改性。用XRD、FT IR分析手段对其进行了表面结构表征 ,采用X衍射荧光光谱仪 (XRF)测定SiO2 包覆量随陈化时间的变化。通过煅烧失重法比较改性前后样品的失重 ,并用动态法测量样品与水的湿润角。结果表明在TiO2 表面存在致密非晶态的硅氧化合物膜 ,纳米TiO2 与水的湿润角增大 ,并且充分分散后在水中的稳定性却得到了很大提高。

SiO_2包覆超细CaCO_3的结构和机理分析

合成了表面包覆 Si O2 的超细 Ca CO3 。通过 XPS,XRD对包覆表面层结构的分析 ,证实了 Si O2 以无定形包覆于 Ca CO3 表面 ,并在其表面形成了 Si- O- Ca键。对 Si O2 包覆超细 Ca CO3 的机理分析结果可知 :Na2 Si O3 的加入量是影响包覆效率的重要因素 ,由于硅酸易自聚 ,控制 Si O2 与 Ca CO3 的重量比约为4 %～ 5 %时为包覆的最佳点 ;Ca CO3 晶粒度大小影响分散性能 ,进而影响包覆效率 ,分散性能好的包覆效率较高。

纳米SiO_2复合涂料的稳定性研究

介绍了纳米SiO2 的特性 ,分析了影响纳米SiO2 复合涂料稳定性的因素 ,对纳米SiO2 进行改性 ,将涂料粒径。

纳米SiO_2在紫外光固化涂料中的应用

考察了纳米ＳｉＯ２对紫外光固化涂膜性能的影响。结果表明，ＳｉＯ２的加入，可提高涂膜的固化速度、涂膜硬度、附着力和低温下的热稳定性。

Ni-SiC和Ni-SiO_2复合镀层性能的研究

对Ni SiC、Ni SiO2 复合镀层在 5 %NaCl+0 .5 %H2 O2 溶液中的腐蚀性能 ,80 0℃高温下的抗氧化性能以及导热性能进行了研究。并利用扫描电镜 (SEM)对镀层微观组织形貌进行了观察和分析。实验结果表明 :与Ni SiC复合镀层比较 ,Ni SiO2 复合镀层在 5 %NaCl+0 .5 % /H2 O2 溶液中以及在 80 0℃高温环境中 ,均表现出较好的耐蚀和抗氧化能力 ;而Ni SiC复合镀层的导热性则明显强于Ni SiO2 ,两者的导热系数随时间延长均略有减少。文中对产生这些性能差异的原因进行了初步的探讨与分析。

Ni/SiO_2复合电镀层高温氧化性能的研究

本试验在普通镀镍液中添加了 10～ 4 0 g/L的二氧化硅微粒 ,成功地制备了 Ni/Si O2 复合镀层 ,随后在 80 0℃下进行了高温氧化试验。研究结果表明 :不同粒径的微粒均可复合进入镀层 ,微粒的进入对镀层的高温抗氧化性有明显影响 ;初始氧化阶段 ,微粒的存在有利于提高镀层的抗高温氧化性能 ;在高温氧化过程中 ,还明显存在基底铜向镍镀层的扩散 ,这可能有利于增强镀层与基底之间的结合力。X射线衍射分析表明 :高温氧化后在镀层表面主要生成 Ni O产物。