Acid corrosion resistance and mechanism of E-glass fibers: boron factor

Acid corrosion and stress corrosion characteristics of E-glass fibers with and without boron (B₂O₃ or B) were carefully studied, using 1 N H₂SO₄ acid at 96 °C and room temperature, respectively. The effect of boron on glass resistance to the acid attack is elucidated in conjunction with structural roles of B, Al, and Ca in the glass. Scanning electron microscopy with energy dispersive spectrometer (SEM/EDS) characterization was performed on the selective fiber samples before and after the acid leaching. For high boron-containing fibers, the results showed the formation of alteration layer enriched in Si as a result of depletion of both Ca and Al. Chemical analysis of the high boron fibers before and after 24 h acid leaching and the solution after 24 h test further confirmed that B, Ca, and Al in the glass fibers preferentially dissolved in the acid solution. Glass fiber dissolution mechanisms were discussed with a proposal that acid corrosion attack in boron-containing E-glass is controlled by hydrolysis of aluminoborate complex species (less than 10 nm) separated from the silicate glass network, whereas the acid corrosion attack in boron-free E-glass is controlled by hydrolysis of the silicate network, where 4-coordinated aluminum in the network is locally charge compensated by Ca.     

无机为主无铬复合钝化的综合对比研究与展望

基于镀锌层表面无铬钝化技术,从钝化膜性质、钝化液稳定性和成膜耐蚀机理3大方面,总结了以硅酸盐、钼酸盐、钛盐以及稀土金属盐为主要成膜物质的4种复合钝化体系的优缺点,认为耐蚀性最优的体系为硅酸盐体系;对比了各体系钝化液稳定性的差异及不同影响因素,总结了不同体系的相应改善方法,认为硅酸盐体系稳定性最好.阐明了硅酸盐、钼酸盐和...     

Model of effect of environmental attack on flaw growth kinetics of glass

The time rate of extension of a single slit-like flaw in glass is modeled assuming the same corrosion mechanism as previously invoked for modeling delayed failure in glass containing a multiplicity of microscopic scratches or flaws. The rate of extension is expressible in terms of the stress intensity K and is in good agreement with the experimental results reported by Wiederhorn and Bolz and others. The model considers a moisture-induced corrosive attack occurring on the exposed flaw surfaces to be governed by local chemical kinetic and thermodynamic considerations, producing a rounding of the flaw tip. This mechanism accounts for the possibility of threshold behavior. The remotely applied stress becomes magnified as shown by Inglis to require the combined effect of the flaw length and tip curvature. These geometric factors in combination with the remotely applied stress mutually interact through the corrosion kinetics to define the net rate of flaw extension.     

镁铝合金表面锶磷化膜的改性及其腐蚀性能研究

利用化学沉积法在镁铝合金表面构筑锶磷化膜,以氢氧化钠和硅酸钠为原料配制磷化膜封孔处理液,对镁合金表面锶磷化膜存在的裂纹和孔洞等缺陷进行封孔处理。通过元素分析及扫描电子显微镜发现改性膜层表面具有Sr、P、O以及Si元素,硅酸钠对锶磷化膜具有良好的封孔作用。通过膜层厚度检测,证明封孔后的锶磷化膜厚度没有发生显著变化。封孔后的锶磷化膜极化电阻比封孔前提升了4倍,而腐蚀电流仅为封孔前的1/3,封孔后膜层的耐腐蚀性能显著提升。     

陶瓷散热片用铜浆玻璃相的制备

厚膜陶瓷散热片的制备工艺一般为丝网印刷铜浆、烧结、化学镀镍3部分。目前印刷在散热片上的铜浆,经化学镀镍工艺后附着力下降,因此研究制备导电性好、导热性优和附着力高的铜浆是制备陶瓷散热片的关键。通过对铜浆玻璃相的制备、玻璃软化温度的测定和玻璃釉在化学镀镍液中的耐蚀性测试,得到了耐蚀性较好的玻璃釉,其玻璃相成分为40%SiO₂-31%Bi₂O₃-5%B₂O₃-3%Al₂O₃-5%TiO₂-3%CaO-4%SrO-5%Na₂O-5%K₂O（质量分数,下同）。     

固化温度对硅酸钠防锈膜性能的影响及其成膜机理

将钢板浸入到硅酸钠溶液中,取出后在不同温度下固化,形成连续透明的保护膜。通过露天耐候试验、塔菲尔极化、中性盐雾试验(NSS)研究了不同温度固化后硅酸钠膜的耐蚀性及耐溶性能,采用扫描电子显微镜(SEM)、傅里叶红外仪、热重(TG-DSC)等对硅酸钠防锈膜的表面形貌及微观结构进行了分析,并对防锈膜的成膜机理进行了探讨。结果表明:高温固化的硅酸钠防锈膜的耐腐蚀性能优于低温固化的硅酸钠膜,200℃固化的硅酸钠膜耐常温水溶解效果最好;随固化温度的升高,膜体系主要发生了2Q3→Q4+H2O,2Q2→Q3+H2O,Q2+Q3→Q3+Q4+H2O等反应,导致膜层中含4个桥氧原子的硅氧四面体(Q4)不断增多,从而形成了致密、均一的三维网状结构硅酸钠膜,膜层耐蚀性更好。     

Formation of crystalline aluminum silicate hydroxide layer during deposition of amorphous alumina coatings by electron beam evaporation

Aluminum oxide films were deposited on fused silica and borosilicate glass substrates by electron beam evaporation, without any substrate heating. Grazing incidence X-ray diffraction measurements found that a layer of crystalline aluminum silicate hydroxide was formed at the interface of the substrate and the amorphous alumina film, the latter transformed to γ-alumina phase on heat treatment at 800 °C. The aluminum silicate hydroxide layer was produced by the chemical reaction between condensing Al and Al–O species, OH⁻ from the residual water vapors in the chamber and Si atoms from the underlying silica and borosilicate glass substrates.     

The kinetics of corrosion of E-glass fibres in hydrochloric acid

The corrosion of glass fibres in acid solution is well known and is thought to be responsible for many instances of failure in glass reinforced plastic materials. Although it is generally accepted that cations are leached from the glass matrix into the acid solution, the precise chemical mechanism and rates of corrosion are still not fully understood. For example, it is not simply the hydrogen ion concentration of the corroding medium that affects the rate of corrosion, but in many cases the anion associated with the acid plays a major role. Anions that can form insoluble salts or complexes with cations in the glass matrix can increase the rate of leaching and hence accelerate the corrosion process. In the case of hydrochloric acid, it has been suggested that chloride anions form complexes with iron(III) ions leached from the glass and this in part increases the rate of corrosion. This paper investigates the corrosion rate of glass fibres exposed to hydrochloric acid at different concentrations and temperatures by measuring the residual strength of the fibres before and after exposure. The leaching rate of cations into solution is also measured using atomic absorption spectroscopy. As expected, increase in temperature increases the rate of corrosion and this can be modelled using a simple Arrhenius plot to determine the activation energy of the process. Strength retention and rates of leaching of individual cations are compared in an attempt to explain the mechanism of corrosion.     

Investigation of the microstructure and corrosion performance of a nanostructured titania-containing hybrid silicate film on mild steel

A pre-treatment system consisting of a nanostructured titania interlayer loaded with an inhibitor and a hybrid silicate film deposited on the TiO₂ layer is shown to provide protection against active corrosion of mild steel. A nanostructured TiO₂ interlayer was prepared on the mild steel surface via controllable hydrolysis of titanium alkoxide. To further improve this pre-treatment, the hybrid silicate film was synthesized from tetraethylorthosilicate and 3-glycidoxypropyltrimethoxysilane precursors. The morphology and structure of the titania interlayer and hybrid silicate film were characterized with atomic force microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy techniques. The corrosion performance of the coatings was examined using electrochemical techniques, including potentiodynamic scanning and electrochemical impedance spectroscopy. The TiO₂ nanostructure calcinated/inhibitor/hybrid silicate system shows enhanced corrosion performance, as confirmed by impedance and polarization measurements.     

Study of an inhibiting aluminosilicate interface by infrared reflection spectroscopy

The corrosion of aluminium alloys in a 0.1 N NaOH medium at 60 °C can be inhibited by using sodium “silicate” (of approximate composition Na₂Si₃O₇·3H₂O) in the presence of aluminate ions. Potential-time and current density-potential curves show the inhibition to be total and almost instantaneous with 0.06 M Si and 0.0018 M Al. IR and electron spectroscopy confirm the presence of a small excess of aluminium, in comparison with a genuine feldspathoid structure, for the amorphous aluminosilicate which is built up on the surface. Although the film is very thin, it can still be characterized by the attenuated total reflection technique, which provides a means of following the kinetics of silicate scale formation in industrial heat exchangers.     

Deposition and corrosion behavior of silicate conversion coatings on aluminum alloy 2024

Potassium silicate was deposited on AA2024 aluminum alloy as environmentally friendly conversion coatings and its corrosion behavior were examined by means of electrochemical impedance spectroscopy, potentiodynamic polarization and surfaces techniques. Potentiodynamic polarization curves show significant decrease in corrosion current density of silicate coated aluminum in NaCl solution. The corrosion resistance was increased with increasing silicate concentration of coating baths. The results indicated that the coating applied from 3 molar silicate baths is more uniform and continuous. The X‐ray diffraction (XRD) and energy discharge spectroscopy (EDS) spectra confirm the existence of silicate film on the AA2024 surface. The coating performance was evaluated in acidic and basic NaCl solution and the results show the stability of silicate conversion coating in these solutions.     

封孔处理对ZLl08铸铝微弧氧化膜性能的影响

微弧氧化膜表面的微孔对氧化膜性能有较大的影响。采用硅酸钠、沸水和常温封孔剂对ZLl08铸铝微弧氧化膜进行了封孔处理,研究了封孔处理对微弧氧化膜性能的影响。结果表明：封孔处理后,微弧氧化膜表面形貌发生了变化,膜厚略有增加,表面硬度显著下降,耐蚀性提高。3种封孔工艺中,硅酸钠封孔后微弧氧化膜表面硬度最高,耐蚀性最好。     

Photochromic coating by vacuum deposition

Photochronic thin films have been obtained by the simultaneous deposition of silicon monoxide, lead silicate, aluminum chloride and copper-sensitized silver halide, followed by a heat treatment in the dark and in air at 100°–200°C for several hours.

The growth of silver halide microcrystals in the film is explained by a simple diffusion-limited process. The fading process can be described by a second order chemical reaction, which has been applied to a type of photochromic glass containing silver halide microcrystals in the glass matrix. The half-fading and half-darkening time of typical films were 10–20 min and 5–20 min, respectively.     

MgF_2镀膜对 ZrF_4-BaF_2-AlF_3-YF_3系统玻璃耐侯性的影响

本文采用红外透射光谱、红外反射光谱、扫描电子显微镜、X 射线能量色散谱仪等方法研究了表面蒸镀 MgF_2镀膜对 ZBAY 系统玻璃耐风化性能的影响,并对该玻璃试样风化侵蚀机理和水化侵蚀机理进行了比较。实验结果表明:ZBAY 系统玻璃的风化侵蚀机理和水化侵蚀机理并不完全相同。ZBAY系统玻璃在较强的风化条件下和较强的水化条件下发生严重的侵蚀。而 MgF_2镀膜能够有效地改善ZBAY 系统玻璃的耐风化和耐水侵蚀性能。     

高掺杂氧化镝的BSA玻璃的制备稳定性研究

为了研究高掺杂稀土情况下B2O3-SiO2-Al2O3体系玻璃的成玻璃性能,玻璃受到不同的化学溶液侵蚀时的抗腐蚀能力,及其腐蚀的机理与规律.通过采用扩张选点方法,探讨了的玻璃的形成区域图;采用UV3101-PC型分光光度仪,DTA和粉末失重法等测试手段研究了玻璃的化学稳定性.通过比较不同的H 浓度,不同场强的稀土离子,以及玻璃表面覆盖层等影响因素对玻璃化学腐蚀速率的影响规律,结果表明,BSA玻璃具有较好的玻璃形成能力;化学侵蚀过程中由于稀土离子的氢氧化物扩散与H 离子交换作用会影响玻璃化学侵蚀程度,因此玻璃耐酸性最差,耐碱性最好;稀土离子的场强越大,玻璃的抗腐蚀能力越强,化学稳定性越好;随着时间的延长由于玻璃表面产生了覆盖层,从而使得玻璃的溶解速率减缓.     

锌镀层硅酸盐钝化膜的耐腐蚀性能

为了考察锌镀层硅酸盐钝化膜的耐腐蚀性能,通过中性盐雾试验、3%CuSO4点滴试验对比研究了锌镀层、硅酸盐钝化膜及低铬酸盐钝化膜的耐腐蚀性能,并用极化曲线电化学测试方法研究了硅酸盐钝化膜的电化学性能。结果表明:硅酸盐钝化膜明显提高了锌镀层的耐腐蚀性能,其耐蚀性优于低铬酸盐钝化膜;硅酸盐钝化膜也明显提高了锌镀层的自腐蚀电位,有效地控制了其腐蚀的电化学过程,属阳极控制型。锌镀层硅酸盐钝化膜具有较高的耐蚀性能。     

Wet chemical etching of silicate glasses in hydrofluoric acid based solutions

The etching of silicate glasses in aqueous hydrofluoric acid solutions is applied in many technological fields. In this review most of the aspects of the wet chemical etching process of silicate glasses are discussed. The mechanism of the dissolution reaction is governed by the adsorption of the two reactive species: HF and HF ₂ ^- and the catalytic action of H⁺ ions, resulting in the breakage of the siloxane bonds in the silicate network. The etch rate is determined by the composition of the etchant as well as by the glass, although the mechanism of dissolution is not influenced. In the second part of this review, diverse applications of etching glass objects in technology are described. Etching of SiO₂ and doped SiO₂ thin films, studied extensively for integrated circuit technology, is discussed separately.     

Characterization of surface layers formed under natural environmental conditions on medieval glass from Siponto (Southern Italy)

In this paper a low-vacuum scanning electron microscope (SEM) coupled with an energy-dispersive X-ray spectrometer (EDX) was used to investigate the alteration processes that occur on silica–soda–lime glass exposed to soil materials and dated from XI to second half of XIII sec. The chemical data were collected for altered glass gel and fresh glass. In order to study the influence of chemical composition on weathering process, 16 glasses have been selected on the basis of the chemical characterization and on the basis of the different corrosion processes present on the fragments. Six selected samples had been produced with the use of natron as fluxer and 10 samples with the use of plant ash as fluxer. The analysed pieces come from Siponto excavations (Foggia, Italy) and they include feet and rims of chalices, fragments of lamps and of globular bottles.     

镀TiN薄膜的保温节能遮阳玻璃

镀有 TiN 薄膜的玻璃是一种新的“热镜”材料。当 TiN 薄膜厚度大于90nm 时,它对红外线的反射率大于75%。小样试验结果表明:使用镀 TiN 的窗玻璃比用普通玻璃节省取暖能源50%以上。此外,TiN 薄膜与玻璃的结合力强,它不被酸、碱、海水所腐蚀,时延性好。     

高温熔融玻璃介质中耐热不锈钢腐蚀行为EI北大核心CSCD

核工业发展及核能的不断开发促使人们开始大力研究绿色环保且安全的核废料处理技术。利用金属容器填装玻璃固化核废料并进行填埋是目前国际上主流的核废料处理技术之一。然而,高温熔融玻璃对金属容器表面产生的高温腐蚀成为加速容器失效的重要原因。因此,深入理解金属在高温熔融玻璃介质中的腐蚀行为是保障核废料安全处理的关键之一。本研究选用S30815耐热不锈钢作为研究对象,深入分析S30815耐热不锈钢在1100℃熔融玻璃中保温不同时间后材料表面腐蚀形态、成分及物相结构。研究结果表明,熔融玻璃首先沿晶界向内腐蚀,然后逐步替代金属材料占据晶界位置并进一步向晶内扩渗,形成腐蚀坑。耐热不锈钢中的Cr,Si元素在腐蚀过程中向熔融玻璃扩渗并导致金属表层元素含量下降,最终促使金属表面由奥氏体转变为马氏体。熔融玻璃对耐热不锈钢的腐蚀属于碱性溶解,金属表面无法形成连续稳定的氧化膜,因此,随着保温时间延长腐蚀将会不断进行。