表面有阳极氧化层的氘化钛热解吸动力学研究

应用反应速率分析方法,测定了氘化钛和表面有阳极氧化层的氘化钛在恒容体系和600～800℃范围内的热解吸反应速率常数,得到氘化钛和阳极氧化的氘化钛热解吸氘的活化能分别为(24.9±1.0)kJ/mol和(38.5±1.2)kJ/mol;氘化钛表面氧化层越厚,表观活化能越大;实验表明氘化钛表面阳极氧化层具有阻氘性能.     

6063铝材微弧氧化最佳电流密度和槽液温度的探讨

目前的铝合金微弧氧化工艺存在电流密度高、槽液温度范围窄等不足,使其应用受到了限制.为此,从铝材低电流密度和宽槽液温度方面研究了6063铝材的微弧氧化工艺,探讨了微弧氧化工艺中电流密度及槽液温度对起弧电压、起弧时间及膜层厚度等的影响.结果表明,同等条件下,电流密度越大,则起弧电压越低,起弧时间越短,膜层越厚;槽液温度越高,则起弧电压越低,起弧时间越短,膜层越厚;在10 min内,得到12μm厚度的膜层,同等时间内比普通阳极氧化膜厚提高4倍;微弧氧化膜的表面显微硬度相对6063铝材高7倍以上.     

钛阳极氧化膜的着色研究

TA2型纯钛植入材料在葡萄糖酸钠电解液中阳极氧化可得到丰富的色彩,增强了钛植入体的美观性和功能性.分析表明:工艺参数对氧化膜质量有着重要的影响.电压是影响膜层色彩的最主要的因素,颜色随着电压的变化而发生规律性的改变.经X射线衍射分析,纯钛表面经阳极氧化处理后,其表面生成了一层非晶态的氧化钛薄膜,并且钛晶体的各个表面沿不同结晶方向的腐蚀速率不相同.通过对氧化膜层显微观察和耐蚀性研究,证明阳极氧化及热处理可大大提高钛氧化膜在模拟体液中的热力学稳定性和耐蚀性,且适当的热处理可使非晶态的钛氧化膜转化为稳定的二氧化钛.     

纯钛材微弧氧化电参数对陶瓷层组织结构的影响

以往就纯钛材表面微弧氧化陶瓷层表面积对提供羟基磷灰石生长条件的研究不多,为此,在Na2HPO4电解液中,采用微弧氧化法在纯钛材表面制得多孔结构的二氧化钛陶瓷层.研究了正向电压、频率对微弧氧化陶瓷层组织结构的影响.结果表明,随正向电压升高,膜厚增加,孔径增大,表面变得粗糙;随频率的增加,膜层表面变得光滑,孔径减小,膜厚减...     

图案化厚膜多孔硅制备与表征

图案化多孔硅是微电子、微机械、光电子器件的重要组成部分.实验以含Si3N4保护层的光刻单晶硅片为基底,采用电化学阳极氧化法制备图案化厚膜多孔硅,分析阳极氧化前后Si3N4保护层表面形貌变化特征和光刻尺寸对图案化多孔硅宽度、膜层厚度的影响规律,表征图案化多孔硅的结构、组成与发光性能.结果表明,氧化前Si3N4保护层局部区域出现枝晶,阳极氧化后形成不均匀孔状结构;制备的图案化多孔硅膜厚62～83μm,其横向扩展程度和膜层厚度均随光刻尺寸增大呈减小趋势;图案化多孔硅微结构含大量不规则裂纹和硅柱,新鲜制备的表面含Si-Hx键,其光致发光峰值波长650nm.     

铝及其合金在30～35℃的硬态阳极氧化

一前言铝在阳极氧化过程中生成的氧化膜包含两层,第一层介于膜金属界面之间,该层无孔隙,叫做阻挡层,在恒电压下,阻挡层的厚度在整个氧化过程保持不变. 同时,随着铝表面氧化膜的生成,其外层容易被电解液腐蚀,这一层叫多孔层,它决定了阳极氧化膜的基本特征. 在恒电压情况下,当膜在电解液中的化学溶解速度等于膜的生长速度时,多孔层的厚度达到最大值,膜的极限厚度与工艺条件,电解液组成、温度、电流密度,电压和合金组成有关. 降低电解液的酸度,增加电流密度,并在低温操作下可以生成致密的厚氧化膜,普通阳极氧化液     

染色和封孔对铝阳极氧化膜结构和耐蚀性的影响

目前,染色和封孔对铝阳极氧化膜的结构和耐蚀性的影响尚不清楚,且有机染色工艺还不够好。采用200 g/L H2SO4电解液在高纯铝表面制备了综合性能良好的阳极氧化膜,通过含芳香烃的有机偶氮染色剂DLM2203和DLM2707对铝阳极氧化膜进行染色处理,用沸水对染色膜进行封孔处理。采用扫描电镜(SEM)、X射线衍射仪(XRD)、红外光谱仪等分析铝阳极氧化膜及染色膜的表面形貌和相组成,并采用动电位极化曲线、电化学阻抗谱等分析铝阳极氧化膜和染色膜的耐蚀性能。结果表明:铝阳极氧化膜染色均匀,表面平整;染色膜经过沸水封闭处理后,其外观颜色变浅;铝阳极氧化膜经染色处理后,厚度和显微硬度都略有增大;沸水封闭导致染色膜厚度略有增大,而显微硬度减小;铝阳极氧化膜的部分孔洞可被DLM2203染色剂充分吸附而成功染色;DLM2707有机染色剂对铝阳极氧化膜有一定的腐蚀作用;铝阳极氧化膜和2种染色膜的相组成相同;偶氮染料分子可以吸附在铝阳极氧化膜的多孔结构内与表面上;染色膜的腐蚀电流密度相对于高纯铝降低了4个数量级,耐蚀性能较好;铝阳极氧化膜与染色膜的阻抗值均处在同一数量级上,耐腐蚀性能基本相近。     

铝合金阳极氧化对氧化膜显微硬度和粘接性能的影响

为了获得膜层显微硬度和粘接强度都较高的铝合金阳极氧化工艺,通过阳极氧化在2024铝合金表面制备氧化膜,根据正交试验来确定氧化工艺参数对铝合金阳极氧化膜显微硬度和粘接性能的影响,采用X射线衍射仪(XRD)、X射线光电子能谱(XPS)、扫描电镜(SEM)等分析氧化膜的相组成、化学组成和表面形貌,并研究电流密度对氧化膜厚度的影响以及氧化膜厚度对膜层显微硬度和粘接强度的影响。结果表明:氧化工艺参数对氧化膜显微硬度的影响程度为电流密度电解液中H_2SO_4浓度氧化时间;采用2种胶粘剂粘接后,氧化工艺参数对氧化膜粘接强度的影响程度有所不同,然而电流密度均为最主要的影响因素;经过阳极氧化处理,铝合金表面的显微硬度和粘接强度均有很大提高,快固结构胶的粘接强度比改性丙烯酸酯胶的高;铝阳极氧化膜的厚度随电流密度增加而增大,在适宜的电流密度范围内氧化膜厚度的增加会导致膜层显微硬度和粘接强度的增大;氧化膜的相组成为非晶结构,主要元素为Al和O,均不因电流密度的变化而变化;铝合金阳极氧化膜表面形貌的优劣、孔隙率与氧化膜显微硬度及粘接强度的大小密切相关。     

建筑铝型材表面氧化膜的制备及其性能

目前,有关阳极氧化工艺参数对铝合金型材表面氧化膜的组织及性能影响的系统研究不多。对建筑用2024铝合金、7075铝合金和6063铝合金进行了表面阳极氧化改性处理,研究了阳极氧化时间、电流密度和冰乙酸添加量对表面氧化膜层的生长行为、表面形貌、膜厚、显微硬度和弹性模量的影响,并分析了其作用机理。结果表明,2024铝合金和7075铝合金表面氧化膜中都存在显微孔洞缺陷,而6063铝合金表面氧化膜较为致密均匀,没有显微孔洞缺陷存在;相同工艺条件下6063铝合金表面氧化膜的生长速度最快,其次为7075铝合金,2024铝合金表层氧化膜生长速度最慢;相同工艺条件下3种合金表面氧化膜显微硬度从小至大依次为:2024铝合金7075铝合金6063铝合金;3种合金氧化膜层的弹性模量从小至大依次为:2024铝合金7075铝合金6063铝合金。     

大厚度复合材料层合板的固化温度场变化规律

本研究通过编写ABAQUS子程序,将固化反应动力学方程引入大厚度复合材料构件固化过程的热传导方程,研究大厚度玻璃纤维/环氧树脂复合材料固化过程中温度分布规律,讨论了板厚与固化温度对层合板内部温度场、固化度场和固化速率的影响。结果表明,大厚度复合材料层合板内部厚度方向温度相差较大,中心点升温幅度最大,厚度方向的温度随着距离中心点位置的增大而降低;上下表面与温度恒定的模具表面接触因而温度不变;固化速率、固化度与温度呈正相关;固化温度一定时,复合材料厚度越大,最大温差ΔTmax越大,需要恢复到初始温度的时间越长,随着厚度的增加,最大温差ΔTmax增大的趋势越小;复合材料厚度一定时,固化工艺温度越高,最大温差ΔTmax越大,需要恢复到初始温度的时间越短,随着厚度的增加,最大温差ΔTmax增大的趋势越小。     

包铝层和氧化时间对2E12铝合金硫酸阳极氧化及膜层性能的影响

对保留表面包铝和去除包铝的2E12-T3铝合金采用硫酸阳极氧化处理工艺,研究了包铝层和氧化时间对铝合金阳极氧化行为及膜层耐蚀性的影响。采用扫描电子显微镜观察氧化膜的表面以及截面形貌,应用动电位扫描极化曲线和电化学阻抗谱对膜层的电化学性能进行分析。结果表明:两种铝合金表面均能形成具有防护性能的阳极氧化膜,膜层随氧化时间延长而增厚。富铜的第二相颗粒会使得不带包铝的2E12铝合金氧化膜具有更多孔洞缺陷,甚至出现微裂纹。保留包铝的2E12铝合金表面氧化膜更厚,孔洞缺陷少,耐蚀性更好。阳极氧化30min和45min的2E12铝合金阳极氧化膜具有较低的腐蚀电流和较高的多孔层阻抗,耐蚀性好。     

Titanium oxide films produced on commercially pure titanium by anodic oxidation with different voltages

Titanium oxide films produced on commercially pure Ti by anodic oxidation with different voltages were analyzed. Anodic oxidation was carried out at room temperature using 1.4 M H₃PO₄ electrolyte and a platinum counter-electrode, in potentiostatic mode under the following conditions: 50 V, 100 V, 150 V, 200 V and 250 V. It was observed that porous titanium layers were formed at all voltage values but morphological differences were observed. Initially, the film was thin but with increasing voltage it broke down locally and porous regions became evident due to the dielectric breakdown. The porosity and the pore size increased with the increasing voltage. The surface morphology in samples formed with 200 V had substantially different porous structures than those formed with other voltage values. The anodic film surface displayed pores and craters formed on the relatively flat ground oxide surface. AFM images showed that higher voltages produced thicker titanium oxide films.     

Effect of Heat Treatment on the Structure and Optical Properties of Porous Anodic Titanium Oxide Films

Inorganic Materials - We have studied the effect of anodizing voltage on the optical properties and structure of anodic titanium oxide films before and after annealing. Annealing at temperatures in...     

Oxidation of thin films of zirconium and Zr-Ti solid solutions on single-crystal silicon

We have studied the oxidation of thin films of zirconium and Zr-Ti (1.2–2.03 at % Ti) solid solutions produced on single-crystal silicon wafers by magnetron sputtering. The films have been oxidized in flowing oxygen at temperatures from 473 to 673 K in a resistance furnace. The phase composition of the resultant oxide layers has been determined. Our results indicate that the oxidation kinetics of thin-film zirconium and Zr-based solid solutions are well represented by a linear-parabolic rate law. The composition, structure, and optical constants of the oxide layers depend on the heat-treatment conditions and the titanium content of the films.     

Influence of Ultrafine‐Grained Layer on Gaseous Nitriding of Large‐Sized Titanium Plate

In this paper, mechanical shot blasting on a large sized titanium plate is conducted to induce severe plastic deformation, which generates an ultrafine‐grained surface layer. The effect of an ultrafine‐grained layer on nitriding is evaluated at nitriding temperatures from 600 to 850 °C. The structural phases and mechanical property improvements are investigated and compared to those of a coarse‐grained specimen by using X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and mechanical property measurements. The results indicate that an ultrafine‐grained layer enhances the nitriding kinetics and produces a thicker nitrided layer than that of a coarse‐grained plate at the same gaseous nitriding temperatures. The improved kinetics are attributed to a greater number of grain boundaries and defects introduced into the titanium plate surface by the mechanical shot blasting treatment. Meanwhile, the surface and cross‐sectional hardness values improve compared to the coarse‐grained plate due to the thicker nitrided layer resulting from deeper nitrogen diffusion.     

Infrared reflection-absorption spectra of anodic oxide films on aluminum

Infrared reflection spectra of anodic aluminum oxide films prepared in boric acid and natural oxide films on aluminum show a common absorption band in the 900–1000 cm^-1 range. This band is shown to be due to the longitudinal mode of the Al-O stretching vibration. In transmission spectra this absorption band is absent; instead one observes the corresponding transverse mode centered around 650 cm^-1.     

Effect of a noble metal coating on a natural aluminum oxide film.

The effect of a noble metal (silver or copper) island film on the vibrational spectrum of a natural aluminum oxide film was studied using the reflection–absorption spectroscopy technique. It was found that the intensity of the absorption band of aluminum oxide near 950 cm⁻¹ changes drastically after the deposition of the metal overlayer. This band intensity increases rapidly with increasing of the silver film thickness more than twice, reaching the maximal value at the silver thickness 0.2 nm, then the band does not change up to the thickness 2 nm. Such behavior takes place only in the presence of aluminum under oxide film. We suggest that this increase of the absorption band intensity is due to the increase of the aluminum oxide film thickness, caused by an electrochemical reaction resulting in aluminum anodic oxidation. For thicker silver films the intensity of the aluminum oxide band falls down slowly due to a metal screening effect.     

Assessment of bioengineering ceramic coatings using the wetting method

The wettability of coatings, including ceramic ones, which show considerable promise for the use on bioengineering products, with physical solution (0.9% NaCl) have been studied. It has been found that the use of coatings of all types under study increases the wetting angles on the surface as compared with the initial metal materials (stainless steel of the 12X18H10T grade, titanium alloy of the BT6-grade, Co-Cr-Mo alloy), which serves as a prerequisite for an improvement in the biocompatibility of implants. The degree of the coating bioinertness increases in the following order: titanium nitride → diamond carbon films → aluminum nitride → titanium oxide (anodic oxide film) → nitride (oxidized) → oxide → titanium oxide (anodic-spark coating).     

Oxidation of iron, aluminium and titanium films in the temperature range 50–200 °C

The oxidation kinetics of iron, aluminium and titanium films have been studied in the temperature range 50–200 °C at a pressure of 0.7 Pa with a piezoelectric quartz microbalance. For titanium, additional measurements in the pressure range 7 × 10⁻³ – 70 Pa have been carried out. All three metals under investigation showed qualitatively common features in their oxidation behaviour: a very fast initial oxygen absorption step, completed in less than 1 min, followed by a slow, temperature-independent oxide growth with logarithmic time law at lower temperatures, and an enhancement of the oxidation rate at higher temperatures. The oxidation curves are compared with the results of model calculations based on the Cabrera-Mott theory.     

化学修饰对NiTi形状记忆合金氧化膜的影响

用X光电子能谱（XPS）研究了NiTi形状记忆合金经酸、碱处理后表面氧化膜成分和结构的变化。结果表明，未经处理的NiTi合金表面最外层氧化膜主要由TiO2、TiO和少量的Ni组成，酸、碱处理后，最外层氧化膜由TiO2、Ni2O3组成，但经碱处理后，氧化膜的厚度大大增加。