Effect of Kovar alloy oxidized in simulated N_2/H_2O atmosphere on its sealing with glass

The effect of Kovar alloy oxidized in simulated field atmosphere on its sealing with glass was studied in this article. After Kovar plates and pins were preoxidized in N2 with 0℃, 10℃ and 20℃ dew points at 1000℃ for different times, Fe304 and Fe203 existed in the oxidation products on Kovar surface, and the quantity of Fe203 increased with increasing dew point and oxidation time. Then they were sealed with borosilicate glass insulator at 1030℃ for 20 rain. The results indicated that the type and quantity of oxidation products would directly influence the quality of glass-to-metal seals. With the increase of oxidation products, gas bubbles in the glass insulator were more serious, the climbing height of glass along the pins was higher, and corrosion of Kovar pins caused from the molten glass was transformed from uniform to the localized.

Effect of phosphate-based sealing treatment on the corrosion performance of a PEO coated AZ91D mg alloy

This study investigated the effect of sealing treatment on the corrosion performance of plasma electrolytic oxidation(PEO)coated AZ91D Mg alloy with and without addition of corrosion inhibitor.The microstructure,phase composition and corrosion property of the sealed and unsealed coatings were evaluated by using scanning electron microscopy(SEM),energy dispersion spectroscopy(EDS),x-ray diffraction(XRD),x-ray photoelectron spectroscopy(XPS),polarization,and electrochemical impedance spectroscopy(EIS)tests.Electrochemical experiments and salt spray tests showed that,after sealing in phosphate solution containing corrosion inhibitor,the corrosion current density of PEO-coated AZ91D decreased more than 10-fold and the anti-corrosion time in a salt spray environment increased more than three-fold.The corrosion rate of the PEO coating slowed down due to the releasing and adsorbing of the corrosion inhibitors in the pores and cracks of the coating during the corrosion process.

Effects of sealing process on corrosion resistance and roughness of anodic films of titanium alloy Ti-10V-2Fe-3Al

Anodic oxide films of titanium alloy Ti-10V-2Fe-3Al were sealed in calcium acetate solution. The morphology and composition of the sealed films were investigated using scanning electron microscopy (SEM), atomic force microscope (AFM) and energy dispersive spectroscopy (EDS). The results show that the sealing process makes the anodic oxide films more uniform. Elemental calcium is presented through the whole depth of the anodic oxide films. The roughness of the anodic oxide films is reduced after the sealing process. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization were used to study the corrosion behavior of the anodic oxide films. It is revealed that the sealing process improves the corrosion resistance of the anodic oxide film of titanium alloy Ti-10V-2Fe-3Al.

Preparation and property of self-sealed plasma electrolytic oxide coating on magnesium alloy

Plasma electrochemical oxidation (PEO) is a surface modification technology to form ceramic coatings on magnesium alloys However,its application is limited due to its defects.This work reports a novel preparation of in-situ sealing of PEO coatings by four-layer voltage and sol addition.The morphology and structure were characterized by scanning electron microscopy (SEM),energy dispersive X-ray spectroscopy (EDS),and X-ray diffractometer (XRD).Image-Pro Plus 6.0 was used to determine the porosity of the coating,which was decreased from 8.53%to 0.51%.Simultaneously,the coating thickness was increased by a factor of four.The anti-corrosion performance of each sample was evaluated using electrochemical tests,and the findings revealed that the corrosion current density of coatings (i_(corr)) of the samples were lowered from 9.152×10^(-2) to 6.152×10^(-4) mA·cm^(-2),and the total resistance (R_(T)) of the samples were enhanced from 2.19×10^(4) to 2.33×10^(5)Ω·cm^(2).The salt spray test used to simulate the actual environment showed that corrosion points appeared on the surface of the coating only at the 336 h.In addition,the mechanism of PEO self-sealing behavior was described in this article.

Effect of solution concentration on sealing treatment of Mg-Al hydrotalcite film on AZ91D Mg alloy

Cerium-based sealing treatment was developed for Mg-Al hydrotalcite film on AZ91D Mg alloy,and the influence of cerium salt solution was investigated to modify the surface integrity and corrosion resistance.Scanning electron microscope(SEM)and X-ray diffraction(XRD)measurements were carried out to analyze the surface morphology and phase composition.The corrosion resistance of Mg-Al hydrotalcite film after sealing treatment was evaluated by the polarization curve and electrochemical impedance spectroscopy(EIS)tests.The results showed that lower concentration of Ce-containing solution was beneficial to seal the micro-cracks on Mg-Al hydrotalcite film,and improve the surface integrity and corrosion resistance;higher concentration of Ce-containing solution could seal fewer micro-cracks,and the corrosion resistance was decreased owing to the disintegration of Mg-Al hydrotalcite film.

Corrosion Behavior of the Rare Earth Sealing Anodized Coating on Aluminum Alloy LY12

Technological process of rare earth sealing anodized LY12 (2024) alloy is introduced. Corrosion behavior of the film was studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results showed that the coating remained passivity at the potential range from the open circuit potential (-780 mV) to -250 mV in NaCl solution. When the potential exceeded -200 mV, corrosion reaction happened on the coating, the results of EIS analysis was consistent with the results of polarization curves.

Study on the Rare Earth Sealing Procedure of the Porous Film of Anodized 2024 Aluminum Alloy

The rare earth sealing procedure of the porous film of anodized aluminum alloy 2024 was studied with the fieldemission scanning electron microscope (SEM) and X-ray energy dispersive spectroscopy (EDS). The results show thatRE solution can form cerium oxide/hydroxides precipitation in the pores of the anodized coating at the beginning ofsealing. At the same time, the spherical deposits formed on the surface of the anodized coating created a barrierto the precipitation of RE solution in the pores. When the pore-structured anodizing film is covered all with thespherical deposits, RE conversion coating will form on the surface of the anodized coating. The reaction of thecoating formation was investigated by employing cyclic voltammetry. The results indicate that accelerator H2O2 actsas the source of O2 by carrying chemical reaction in course of coating formation. In the mean time, it maybe carrieselectrochemical reaction to generate alkaline condition to accelerate the coating formation. The porous structure ofthe film is beneficial to the precipitation of the cerium hydroxides film.

Sealing Effect of KAl(SO_(4))_(2)Solution on the Corrosion Resistance of Anodized Aluminum Alloy

The 2024 anodized aluminum alloy film was sealed by KAl(SO_(4))_(2)solution and the effect of sealing on corrosion resistance was investigated by means of potentiodynamic polarization curves,electrochemical impedance spectroscopy,and X-ray photoelectron spectroscopy.The experimental results show that the optimal parameters for KAl(SO_(4))_(2)sealing are 35℃,with the pH value of 8,the concentration of 8 g/L,and the sealing time of 3 min.The corrosion resistance of the KAl(SO_(4))_(2)sealed sample can be significantly improved than that of unsealed one,and is obviously superior to that of the conventional hydrothermal sealed sample.Furthermore,X-ray photoelectron spectroscopy demonstrates that more Al(OH)_(3)will be formed in the process of KAl(SO_(4))_(2)sealing,which will shrink the diameter of the microporous and therefore results in the excellent corrosion resistance.

HIGH TEMPERATURE OXIDATION AND STRUCTURE OF SCALE AND WHISKERS FOR Fe-Ni-Cr SEALING ALLOYS

The oxidation rate,the growth,morphology and structure of oxide scale and whiskers for Fe-Ni-Cr sealing alloys in H_2-H_2O atmosphere at high temperatures have been studied. The growth rate of scale is controlled by diffusion.The scale is composed of Cr_2O_3 and spinel(Fe,Mn)O·Cr_2O_3 and the oxide whisker,are spinel(Fe,Mn)O·Cr_2O_3.

STUDY ON PROPERTY PREDICTION FOR SEALING ALLOYS

This paper describes a model of property prediction for alloys using the mapping function and self-learning ability of artificial neural network. By learning from experimental data, the neural network induces the relationship between composition, processing and properties of alloys, and predicts the properties with given composition and processing parameters of new alloys.The verification of sealing alloys demonstrates that the artificial neural network is an effective method for materials design and properties prediction.

Method of analyzing vibration characteristics of armature system of hermetically sealed electromagnetic relay

Published research is minimal on vibration characteristics of hermetically sealed electromagnetic relay (EMR) ex- posed to mechanical environment. The vibration characteristics of armature system, link contact system with electromagnetic system will cause EMR malfunction. The nonlinear dynamics model of armature systems was studied by considering electro- magnetic attraction force and opposite mechanical force in this paper. Angular displacements of armature under different sinu- soidal vibration conditions are solved in order to obtain the failure mode result from armature system. Vibration tests showed the presented analyzing method is suitable for EMR. The conclusions are instructive for increasing vibration resistance of armature systems of EMR, and are significant for reliability design of switch apparatus.

Matched glass-to-Kovar seals in N_2 and Ar atmospheres

The oxidation of Kovar alloy was investigated, the wetting and spreading behavior of hard and soft glasses on Kovar alloy were studed by using the sessile drop method, and the quality and the seal strength of glass-Kovar seals were tested. The experimental results indicated that the preoxidation of Kovar alloy for approximately 10 min at 700℃ in air resulted in excellent adherence in glass-Kovar seals. The wetting and spreading behavior of glass on preoxidized Kovar alloy were superior to that on nonoxidized Kovar alloy. The wetting ability of ASF110 glass, at 950℃ and 980℃ in Ar and N2 atmospheres, was significantly superior to that of ASF200R and ASF700 glasses. The seal quality of the glass-preoxidized Kovar seal was superior to that of the glass-nonoxidized Kovar seal. The shear strength of the ASFll0 glass-preoxidized Kovar seal, which was prepared at 980℃ for 20 min in an Ar atmosphere, was approximately 3.9 MPa.

Electrochemical behaviors of anodic alumina sealed by Ce-Mo in NaCl solutions

The elimination of toxic materials in sealing methods for anodic films on 1070 aluminum alloy was studied. The new process uses chemical treatments in cerium solution and an electrochemical treatment in a molybdate solution. Potentiodynamic polarization and electrochemical impedance spectroscopy(EIS) were used to study the influences of sealing methods on the corrosion behavior of anodic films in NaCl solutions. The results show that the Ce-Mo sealing makes the surface structure and morphology of anodic films uniform and compact. Ce and Mo produce a cooperative effect to improve the corrosion resistance of anodic films. Anodic films sealed by Ce-Mo provide high corrosion resistance both in acidic and basic solutions.

基于Bubble小波函数的印鉴鉴别

利用 Bubble小波函数 ,通过 Mallat算法可对印鉴图像进行小波分解和边缘检测 ,在此基础上 ,提取由傅里叶系数所导出的形状特征 ,然后利用神经网络分类器进行训练 ,继而实现印鉴的自动鉴别。

Enhanced protective coatings on Ti-10V-2Fe-3Al alloy through anodizing and post-sealing with layered double hydroxides

Anodic oxidation is a prevalent technique to introduce superior corrosion and wear resistance upon the surface of titanium(Ti)alloys,in which the selection of appropriate electrolytes and defect-sealing strategies is a key.This study aims to address such issues through anodizing Ti-10V-2Fe-3Al alloy in malic acid,followed by a post-sealing treatment with Mg-Al layered double hydroxides(LDHs).The characteristics of the samples were investigated using scanning electron microscopy(SEM),atomic force microscopy(AFM),glow discharge optical emission spectroscopy(GDOES),X-ray diffraction(XRD)and energy-dispersive X-ray spectroscopy(EDS).SEM micrographs reveals that the anodic coating had a surface full of bulges and cracks,and was almost sealed by the following LDHs treatment.XRD pattern indicate that the anodic coating was mainly consisted of amorphous TiO2 with a small fraction of anatase,but its crystallization degree was increased through the post-sealing.Moreover,electrochemical and tribological measurements demonstrate that corrosion current density was 2.8×10-6,2.0×10-7,5.9×10-9A cm-2,and wear rate was 1.45×10-3,1.30×10-4 and 6.90×10-5 mm3 N-1 m-1 for respective bare Ti-10V-2Fe-3Al alloy substrate,anodized specimens without and with the LDHs post treatment.Finally,a plausible wear mechanism was proposed.

Nickel-free sealing technology for anodic oxidation film of aluminum alloy at room temperature

Different additives were added into the potassium fluorozirconate solution to prepare different nickelfree sealing reagents,with which the anodic oxidation film of aluminum alloy was sealed at room temperature.The phosphor chromic acid weight loss method was used to evaluate the sealing effects.Using electron scanning microscopy(SEM),the surface and cross-sectional micromorphologies of the anodic oxidation films sealed by different fluorozirconate sealants were observed.The position and state of zirconium element distribution in the film hole were investigated by the further quantitative and distribution analysis of Zr element.This study provides an experimental evidence for the theoretical studies of fluorozirconate-sealed anodic oxidation films.It is shown that the fluorozirconate has good sealing effects and has a wide prospect for sealing the aluminum alloy samples.Its products were highly corrosion resistant,and were filled in the openings of the micropores in the oxide film.

Cerium-Based Sealing Treatment of Mg–Al Hydrotalcite Film on AZ91D Magnesium Alloy

An environment-friendly cerium-based sealing treatment was developed to improve the surface integrity and corrosion resistance of Mg–Al hydrotalcite film on AZ91D magnesium alloy. The cerium dioxide was generated through three stages namely nucleation, growth and dissolution, modifying the surface of AZ91D Mg alloy, and the hydrotalcite film became integral after being treated for 30 min. The results of polarization curves showed that the anti-corrosive performance of the hydrotalcite film was enhanced by the sealing treatment. Moreover, the immersion tests and electrochemical impedance spectrum measurements also demonstrated that the sealed hydrotalcite film provided a longer-term protection of magnesium alloy from corrosion as compared to the unsealed one.

Effect of SrO Content on Structure,Thermal Properties and Chemical Stability of Bi2O3-B2O3-ZnO-SrO Low-melting Glass for Si-Al Alloy Package

The 40Bi2O3-30B2O3-(30-x)ZnO-xSrO (x=0-15mol%,BBZSr) glass system was prepared by the conventional melt quenching method.The effect of SrO addition on structure,thermal properties,chemical stability and sealing performance of BBZSr glass were investigated thoroughly.The experimental results show that the total proportions of [BO3] group and [BO4] group decrease and the vibrations of [BiO3] group and [BiO6] group become weaker with the increase of SrO addition content,suggesting the glass network structure is strengthened owing to the SrO addition.Hence,both the thermal and chemical stability were significantly improved as the SrO content was increased.When the SrO content increased from 0 to 15mol%,the glass transition temperature and softening temperature slightly increased from 380 to 388 ℃ and from 392.7 to 402.2 ℃,respectively,meanwhile the coefficient of thermal expansion also increased from 10.49×10^-6 to 11.16×10^-6/℃ (30-300 ℃).The BBZSr glass with 15mol% SrO exhibited excellent comprehensive properties with low glass transition temperature(384.9 ℃),low softening temperature(400.3 ℃),high coefficient of thermal expansion (11.14×10^-6 ℃,30-300 ℃),good thermal and chemical stability.Besides,the glass had the good wetting behavior and sealing performance for Al-50%Si alloy.

Characterization of the Protective Surface Films Formed on Molten AZ91D Magnesium Alloy in SO_2/Air Atmospheres in a Sealed Furnace

Surface films that formed on molten AZ91D magnesium alloy in S02/air cover gases at 680 ℃ in a sealed furnace were characterized by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and Auger electron spectroscopy. It is revealed that the film formed on molten AZ91D alloy surface in cover gas with high air content can prevent the molten AZ91D alloy from oxidation and ignition. The surface film contained three elements, namely magnesium, oxygen and sulfur, and was mainly composed of MgO and MgS. The properties of the film depended on air content in the cover gas and holding time. Thermodynamic calculation showed that MgSO4 was the stable phase, and it was concluded that the formation of MgS04 was important for the formation of the protective surface film in S02/air atmospheres.

Kovar合金的可控氧化及其与硼硅玻璃润湿性研究

本文在不同氧化气氛条件下对Kovar合金进行高温氧化处理,优化得到Kovar合金最佳氧化工艺,并与硼硅玻璃进行润湿试验和封接试验,同时运用XRD、XPS、SEM、EDS等分析手段对氧化成分和封接界面进行机理分析。结果表明,高温下Fe、Co、Ni元素均参与了氧化反应,Kovar合金氧化动力学遵循抛物线规律,Kovar合金的最佳氧化工艺为:氧化温度850℃、氧化时间11.7 min、N_(2)流量1 L/min、露点30℃。不同气氛氧化处理后,Kovar合金与玻璃封接的气密性变化较小,玻璃与表面氧化物为Fe_(3)O_(4)的Kovar合金封接后抗拉强度最大。