Fabrication of a Conductometric Sensor for Crevice Corrosion Studies

2002 ◽  
Vol 729 ◽  
Author(s):  
Xiaoyan Wang ◽  
Robert G. Kelly ◽  
Jason S. Lee ◽  
Michael L. Reed
Keyword(s):  
Thin Film ◽  
Real Time ◽  
Crevice Corrosion ◽  
Metal Ion ◽  
Microelectromechanical Systems ◽  
Spatial Information ◽  
Ion Concentration ◽  
Potentiometric Sensors ◽  
Conductometric Sensor

AbstractMicrofabricated crevice corrosion samples have been employed in experiments that provided important information necessary for developing an accurate, comprehensive, and reliable crevice corrosion model. Acquiring real-time spatial information of crevice corrosion is also essential in analyzing corrosion processes. Integration of arrays of solid-state microsensors, such as conductometric sensors, pH and other ion concentration potentiometric sensors, into the crevice corrosion samples will allow for in-situ real-time data acquisition. In the present work, crevice corrosion samples with conductometric sensor arrays are made using the techniques developed for thin film semiconductor processing and microelectromechanical systems (MEMS) fabrication. The crevice corrosion testing sample is constructed by coupling a crevice former to a crevice substrate and has a uniform crevice gap. A conductometric sensor array built on a silicon wafer is incorporated into the crevice former. Each of these sensors is composed of a pair of thin film gold electrodes, which enables in-situ spatial conductivity analysis of crevice corrosion. Information about metal ion concentration and active chemistry inside the crevice can also be obtained.

Microfabricated Crevice Former with a Sensor Array

2001 ◽  
Vol 687 ◽  
Author(s):  
Xiaoyan Wang ◽  
Robert G. Kelly ◽  
Michael L. Reed
Keyword(s):  
Real Time ◽  
Crevice Corrosion ◽  
Sensor Array ◽  
Microelectromechanical Systems ◽  
Spatial Information ◽  
Ph Sensor ◽  
Corrosion Testing ◽  
Array Configuration ◽  
Selective Membrane ◽  
Microsensor Arrays

AbstractMicrofabrication of crevice corrosion samples is of importance in developing an accurate, comprehensive, and reliable crevice corrosion model, and real-time acquisition of corrosion information is also essential. Solid-state microsensor arrays have been used for detecting potential, pH, and ion concentrations, and their integration into crevice corrosion testing samples will provide real-time spatial information of crevice corrosion. The crevice corrosion testing sample is constructed by coupling a crevice former to a crevice substrate and has a uniform crevice gap. In this paper we present a crevice former incorporating a potentiometric, ion- selective membrane microelectrode pH sensor array. The crevice former is built on a silicon wafer using microelectromechanical systems (MEMS) fabrication and thin film semiconductor processing techniques, and consists of an array of five independent sensing microelectrodes. The array configuration allows for in-situ spatial pH analysis of crevice corrosion based on information from each sensor. The fabrication details of the crevice former with microelectrode sensor will be elaborated.

Microfabrication of Crevice Corrosion Samples

2000 ◽  
Vol 657 ◽  
Author(s):  
Xiaoyan Wang ◽  
Robert G. Kelly ◽  
Jason S. Lee ◽  
Michael L. Reed
Keyword(s):  
Crevice Corrosion ◽  
Computational Models ◽  
Microelectromechanical Systems ◽  
Spatial Information ◽  
Semiconductor Device ◽  
Device Fabrication ◽  
Metal Electrodes ◽  
Electrical Connections ◽  
Microfabrication Techniques

ABSTRACTA major challenge in developing computer models for crevice corrosion lies in fabricating appropriate experimental crevice samples. The geometry and dimensions of these samples must be controlled to a high order of precision in order to be amenable for comparison to computational models. In this work we report an effort to construct crevice samples with rigorously defined dimensions by using microfabrication techniques developed for microelectromechanical systems (MEMS). These techniques include microfabrication with SU- 8, electroplating, and other standard semiconductor device fabrication techniques as well. The crevice substrates contain one-dimensional arrays of metal electrodes to be studied, which are isolated by walls of SU-8. The electrodes have individual electrical connections so that spatial information of the in-situ corrosion process can be obtained. The crevice formers with SU-8 posts were coupled to crevice substrates to maintain a uniform crevice gap. Further, crevice formers with regular rectangular subcrevices were fabricated to study the roles of subcrevices in crevice corrosion.

scholarly journals Why In Situ, Real-Time Characterization of Thin-Film Growth Processes?

MRS Bulletin ◽  
1995 ◽  
Vol 20 (5) ◽  
pp. 14-17 ◽  
Author(s):  
Orlando Auciello ◽  
Alan R. Krauss
Keyword(s):  
Thin Film ◽  
Real Time ◽  
Analytical Methods ◽  
Film Growth ◽  
High Temperature Superconductors ◽  
Thin Layers ◽  
Thin Film Growth ◽  
Sampling Depth ◽  
Growth Environment

It is anticipated that a new generation of advanced electronic and optical devices will involve the synthesis of diverse materials in single or multielement thin-film form, or in layered heterostructures. These devices will most likely involve diverse materials such as high-temperature superconductors, ferroelectric, electrooptic, and optical materials; diamond; nitrides; semiconductors; insulators; and metals in the form of ultra-thin layers with sharp interfaces in which the layer thickness may reach atomic dimensions. Therefore, it becomes increasingly important to be able to monitor the deposition process in situ and in real time, particularly for complex multicomponent oxides or nitrides, in which the production of the desired phase is a highly sensitive function of the growth conditions, often requiring relatively high-pressure oxygen or nitrogen environments up to several hundred mTorr, and in some cases, several Torr. Consequently, the growth environment for many of these materials is incompatible with conventional surface-analytic methods, which are typically restricted to high-or ultrahigh-vacuum conditions. New deposition and analytical methods, or adaptation of those already established, will be required.Since thin-film growth occurs at the surface, the analytical methods should be highly surface-specific, although sub-surface diffusion and chemical processes also affect film properties. Sampling depth and ambient-gas compatibility are key factors which must be considered when choosing in situ probes of thin-film growth phenomena. In most cases, the sampling depth depends on the mean range of the exit species (ion, photon, or electron) in the sample.

Impact of pH on CdII partitioning between alginate gel and aqueous media

2009 ◽  
Vol 6 (4) ◽  
pp. 305 ◽  
Author(s):  
Erwin J. J. Kalis ◽  
Thomas A. Davis ◽  
Raewyn M. Town ◽  
Herman P. van Leeuwen
Keyword(s):  
Functional Groups ◽  
Metal Ion ◽  
Ion Concentration ◽  
Local Concentration ◽  
Relevant Parameter ◽  
Donnan Potential ◽  
Alginate Gel ◽  
Bulk Medium ◽  
Ph Dependent

Environmental context. Biogels, such as those in cell walls or biofilm matrices, generally comprise negative structural charge which leads to accumulation of positively charged species, e.g. metal ions. The magnitude of the effective charge, and hence the local chemical speciation within the gel phase, is pH dependent. In situ speciation measurements in biogels, such as the model alginate studied in this work, offer a better estimate of bioavailable concentrations than does analysis of the surrounding aqueous medium. Abstract. Many microorganisms exist in a biogel-mediated micro-environment such as a cell wall or a biofilm, in which local concentrations of ionic nutrients and pollutants differ from those in the surrounding bulk medium. The local concentration is the relevant parameter for considerations of bioavailability. These modified concentrations arise as a consequence of the negative charges within biogels which may induce a Donnan potential inside the biogel phase. For metals, the net effect on the speciation within the biogel, relative to the bulk medium, is an enhancement of the concentration of free cations. Since the structural charge in the biogel arises from protolytic functional groups, the Donnan potential is pH dependent. Here we apply in situ voltammetry to measure the free metal ion concentration inside alginate gel as a function of pH. In the pH range 3 to 7, the speciation of CdII within this model biogel can be explained by specific binding to carboxylic functional groups and electrostatic binding resulting from the Donnan potential.

Crystallization of thin-film Si monitored in real time by in-situ spectroscopic techniques

2007 ◽  
Vol 18 (S1) ◽  
pp. 309-313 ◽  
Author(s):  
P. Stradins ◽  
C. W. Teplin ◽  
D. L. Young ◽  
Y. Yan ◽  
H. M. Branz ◽  
...  
Keyword(s):  
Thin Film ◽  
Real Time ◽  
Spectroscopic Techniques

Optical Second Harmonic Generation as a Tool for In Situ, Real-Time Monitor of Thin Film Epitaxial Growth

2014 ◽  
Vol 605 ◽  
pp. 223-226
Author(s):  
Andrea Rubano ◽  
Tim Günter ◽  
Martin Lilienblum ◽  
Domenico Paparo ◽  
Lorenzo Marrucci ◽  
...  
Keyword(s):  
Thin Film ◽  
Second Harmonic Generation ◽  
Real Time ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
High Energy ◽  
Direct Access ◽  
Human Machine Interaction ◽  
Optical Second Harmonic Generation

Oxide-based hetero-structures are promising candidates for building the next generation of functional devices. In order to achieve this goal, it is required to have solid and reliable sensors for monitoring the growth of thin films with single-atomic-layer sensitivity. So far, the most popular in-situ diagnostic tool is Reflection High Energy Electron Diffraction, which provides information on the structural properties of the growing films, and not a direct access to the desired interfacial physical properties of interest. Furthermore, it needs a strong human-machine interaction, preventing its use into industrial mass production. Standard optics applied on buried interfaces suffers the disadvantage to have a probing depth which is orders of magnitude larger than the interface layer. Here we propose to overcome this problem by resorting to optical Second Harmonic Generation and we present some example to show the potential of this technique as a real-time monitor system for thin-film crystal growth.

Study on Embedding and Integration of Microsensors Into Metal Structures for Manufacturing Applications

2006 ◽  
Vol 129 (2) ◽  
pp. 416-424 ◽  
Author(s):  
Xudong Cheng ◽  
Arindom Datta ◽  
Hongseok Choi ◽  
Xugang Zhang ◽  
Xiaochun Li
Keyword(s):  
Thin Film ◽  
Real Time ◽  
Temporal Resolution ◽  
Elevated Temperatures ◽  
Transient Temperature ◽  
Manufacturing Processes ◽  
Metal Structures ◽  
Metal Tooling ◽  
Critical Locations

Real time monitoring, diagnosis, and control of numerous manufacturing processes is of critical importance in reducing operation costs, improving product quality, and shortening response time. Current sensors used in manufacturing are normally unable to provide measurements with desired spatial and temporal resolution at critical locations in metal tooling structures that operate in hostile environments (e.g., elevated temperatures and severe strains). Microsensors are expected to offer tremendous benefits for real time sensing in manufacturing processes. Rapid tooling, a layered manufacturing process, could allow microsensors to be placed at any critical location in metal tooling structures. However, a viable approach is needed to effectively integrate microsensors into metal structures during the process. In this study, a novel batch production of metal embedded microsensor units was realized by transferring thin-film sensors from silicon wafers directly into nickel substrates through standard microfabrication and electroplating techniques. Ultrasonic metal welding (USMW) was studied to obtain optimized process parameters and then used to integrate nickel embedded thin-film thermocouple (TFTC) units into copper workpieces. The embedded TFTCs successfully survived the welding tests, validating that USMW is a viable method to integrate microsensors to metallic tool materials. Moreover, the embedded microsensors were also able to measure the transient temperature in situ at 50μm directly beneath the welding interface during welding. The transient temperatures measured by the metal embedded TFTCs provide strong evidence that the heat generation is not critical for weld formation during USMW. Metal embedded microsensors yield great potential to improve fundamental understanding of numerous manufacturing processes by providing in situ sensing data with high spatial and temporal resolution at critical locations.

Real Time Ellipsometric Study of Boron Nitride Thin Film Growth

1995 ◽  
Vol 410 ◽  
Author(s):  
E. Bertran ◽  
A. Canillas ◽  
J. Campmany ◽  
M. El Kasmi ◽  
E. Pascual ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Refractive Index ◽  
Boron Nitride ◽  
Real Time ◽  
Film Growth ◽  
Thin Film Growth ◽  
Si Substrates ◽  
Rf Glow Discharge

ABSTRACTWe present an in situ study of the growth of boron nitride thin films by real time ellipsometry. Films were produced in a PECVD reactor by rf glow discharge decomposition of ammonia (pure) and diborane (1% in hydrogen), on Ni-Cr coated c-Si substrates placed either on the powered electrode or on the grounded electrode of the reactor. A fast phase-modulated ellipsometer performed the real time monitoring of the growth processes at 350 nm. The ellipsometric angle trayectories were obtained through an autocalibrated method, especially suitable for the in situ optical analysis of transparent thin films. We applied several thin film growth optical models (homogeneous, two-layer, surface roughness) to analyze parameters of the films such as refractive index, extinction coefficient, roughness and deposition rate. In all the cases studied, the two-layer model fits well with the ellipsometric measurements, but a more sofisticated model considering a variable refractive index could better describe these films.

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