Search Results

A low temperature electrolysis process has been developed for the treatment of solid waste material and urine. Experiments are described in which organic materials are oxidized directly at the surface of an electrode. Also, hypochlorite is generated electrochemically from chloride component of urine. Hypochlorite can act as a strong oxidizing agent in solution. The oxidation takes place at 30-60°C and the gaseous products from the anodic reaction are carbon dioxide, nitrogen, oxygen. Hydrogen is formed at the cathode. Carbon monoxide, and nitrogen oxides and methane were not detected in the off gases. Chlorine was evolved at the anode in relatively low amounts.

Adoption of a new machining method such as ECM leads to a series of experiences which affect equipment, product application, installation, and personnel. This paper will review highlights of the progress made by Garrett-AiResearch in utilizing the ECM process and equipment and will outline some anticipated future activities. Modernization of an early model ECM machine is described to illustrate one of the operations being pursued in the constant battle against obsolescence.

Electrochemical Metallizing, a process whereby metal is selectively applied to rebuild and restore worn damaged, mismachined and corroded components, has long enjoyed use as an aircraft engine manufacturing tool. Repair coatings to corroded areas also have a long history of success. More recently, this high-speed coating process has been utilized as a turbine engine repair tool in F.A.A. approved overhaul and repair shops. Meeting both military and commercial aircraft specifications, electrochemical metallizing can be added to compliment an F.A.A. repair station's rework methods, increasing overhaul capabilities. Worn stators, shaft diameters and endbell housings are easily rebuilt with electrochemical metallizing. Damaged gearbox faces can be restored. Many rotational engine components have been successfully refurbished. The paper will explore the use of electrochemical metallizing to repair these engine components.

Electrochemical metallizing (ECM) has been widely used in aircraft maintenance and OEM applications, but is far from reaching it's potential. Although ECM has been around for more than twenty years, it still represents a small part of metal finishing as a whole, thus making information describing the process not readily available. Most of the problems experienced with the process, aside from solution contamination, stem from improper tooling design, and will be the focus of this paper. Tooling and other areas covered will be as follows: 1 Anode design: choosing proper anode design for the job. 2 Flow-thru anodes: for more efficient distribution of electrolytes. 3 Precision build-ups: plating to size. 4 Solution and anode cooling: to prevent over-heating of solutions at the anode/work-piece interface and the effects on the deposit. 5 Masking techniques: how to make the tape work for you by reducing high and low current density problems. 6 Heavy build-up: depositing .050″ or more.

The results of the studies of two methods carried out for water saturation with the trace elements are proposed. In the first method the water saturation is realized due to the adsorption equilibrium that sets on the sorbent surface and into the solution. This method has a resourse of 1,6 l/g. In the other method the electric current using makes possible both to control the process of the saturation and to increase the mineralizer's resource in 10 times as compared with the first one due to the deeper ions extraction from the charcoal surface. The data obtained may be taken as a basis for the development of the adequate thechnology and construction.

Lithium plating is an important failure factor for lithium ion battery with carbon-based anodes and therefore preventing lithium plating has been a critical consideration in designs of lithium ion battery and battery management system. The challenges are: How to determine the charging current limits which may vary with temperature, state of charge, state of health, and battery operations? Where are the optimization rooms in battery design and management system without raising plating risks? Due to the complex nature of lithium plating dynamics it is hard to detect and measure the plating by any of experimental means. In this work we developed an electrochemical model that explicitly includes lithium plating reaction. It enables both determination of plating onset and quantification of plated lithium. We have studied the effects of charging pulses on homogenous plating in order to provide guidance for lithium ion battery design in hybrid applications.

We report on the use of electrically-conducting diamond thin-film electrodes for the detection of iodine and its disinfection by-products in water supplies. The phenolic byproducts, 2-iodophenol, 4-iodophenol, and 2,4,6-triiodophenol, were investigated. Cyclic voltammetry was used to study the oxidation reaction mechanism. Flow injection analysis with amperometric detection was employed to determine the detection figures of merit. Two types of diamond thin-film were evaluated: microcrystalline and nanocrystalline. Both diamond types yielded a sensitive, reproducible and stable response for the oxidative detection of 2-iodophenol and 4-iodophenol. For example, the linear dynamic range for the most common phenolic by-product, 2-iodophenol, was 5 orders of magnitude, the minimum concentration detected (S/N ≥ 6) was 0.44 ppb, and the response precision was ca. 4%.

There is a great need for reliable environmental sensors that can monitor the concentrations of gases and vapors such as oxygen, carbon dioxide, carbon monoxide, water vapor and other contaminants of the cabin air in a manned space station. Honeywell has developed a new class of electrochemical gas sensors based on nonaqueous electrolytes. Sensors with three electrode configuration and gold sensing electrodes have been fabricated and used for monitoring both carbon dioxide and oxygen with the capability to monitor water vapor using linear scanning voltammetry. Sensors with platinum sensing electrodes have been used to monitor low concentrations of toxic gases such as carbon monoxide and nitrogen oxides with potential capability to monitor organic contaminants. Experimental results obtained with these low-power and microprocessor-based sensors will be presented.

Electrochemical NOx sensors for emission control of automotive exhaust gas were prepared coupling pellets of yttria-stabilized zirconia (YSZ), an oxygen ion conductor, with thick films of a semiconducting oxide (WO3) as an auxiliary phase. The obtained sensors were wholly exposed to the same atmosphere. Electromotive force (EMF), polarization curves and amperometric measurements were performed in air and at different concentrations of NO2 in air, at selected temperatures. Stable EMF values and fast response times were obtained. The sensors showed non-linear polarization curves. The role played by the electrolyte/electrode interface was determined by electrochemical impedance spectroscopy (EIS) tests: exposure to NO2 did not affect the bulk but only the electrolyte/electrode interface.

Thin films deposited by magnetron sputtering are review in terms of their potential and present uses in the aircraft industry. The aircraft alloys substrates were Ti-6Al-4V and Incoloy 800HT, using a target of yttrium stabilized zirconia (YSZ) with nominal composition of 8% Y2O3 (wt%) and the remainder of ZrO2. The chemical composition of the films was determined by X-ray energy dispersion (EDS). The electrochemical noise behavior show that the coatings decreased propagation of pitting, leading to a state of passivation or uniform corrosion, and also possess superior corrosion resistance over the individually substrates.

Disinfection of water and wastewater was proven to be feasible using a Breadboard Electrochemical Ozone Generator (EOG). A static gas/liquid separator, containing a microporous, hydrophobic membrane, was tested with the Breadboard EOG, and was found to increase the concentration of the ozone (O3) dissolved in the water. Distilled water and selected wastewaters were disinfected, achieving dissolved O3 concentrations up to 3 mg/L. The hardware is capable of operating in 0-g and 1-g environments. An end-item Electrochemical Ozonator (EO), sized to disinfect 116 kg of potable water per day, was projected to weigh 1.2 kg and consume only 18.5 W.

Electromechanical Actuation Systems (EMAS) using advanced state-of-the-art technology offer significant benefits in primary flight control applications. Fighter and attack aircraft present the greatest challenge, but studies have shown feasibility for those applications. The use of samarium cobalt “inside-out” DC motors, solid-state power switching, and microprocessor control of commutation, current, and frequency are the advances that have made EMAS contenders for military aircraft applications. Benefits include elimination of hydraulic systems, improved logistics, increased reliability, and lower life-cycle costs. The studies addressed actuation of canard and rudder control surfaces on supersonic Navy-fighter aircraft.

A concept for an electrochemical reactor acting as a trap for the removal of soot particles from diesel exhaust gas has been developed and presented earlier [1]. Only small scale flat plate samples tested with synthetic exhaust gas was presented. Since then, the sample size has been increased, and test on a diesel engine in a test bench has been carried out. Various concepts for the establishment of a sufficient filtering surface and for the electrical connections have been tested, and the construction of a muffler with an electrochemical reactor installed has been initiated. This is to be on a passenger car for on-road test. The preliminary bench test indicates a soot removal efficiency of 75-90% with no accumulation of soot at the reactor, at temperatures above 250°C. A separate project has been started to evaluate the possibilities of lean NOx removal on a similar reactor. Results from this will be reported separately.

With surging interest in high energy density solid state lithium rechargeable batteries and discoveries of high voltage cathode materials such as LiMn2O4 and LiCO2, it is imperative that useful solid electrolytes possess a voltage window of about 5 volts. These solid electrolytes after being assembled into a cell will be subjected to a dc bias potential equal to cell voltage. The ability of composite electrolytes to withstand the dc potential has been determined, discussed, and presented. The experimental data include linear sweep and cyclic voltammetry measurements. The data are analyzed in terms of dielectric breakdown, ionization, and electrodic reactions.

Lithium ion batteries offer more power and longer cycle life than traditional technologies for many different applications. However, Li-ion batteries are new in the aviation applications and due to the lack of experience they are preventively removed from service before any problems may occur with the battery. This currently makes them unnecessarily expensive. A health diagnostic system needs to be developed and installed in the battery will show the state of health reducing maintenance costs. The purpose of this paper is to show Saft's approach to better understand cell aging through testing using reference electrodes. The aging of the cell anode and cathode will be analyzed under aircraft conditions to determine points of failure. The data acquired will then be used by Global Technology to create a prognostics health management (PHM) model for aviation.

Corrosion behavior of brass CuZn15Fe, brass CuZn30 and aluminum in automotive coolants was studied with electrochemical methods. Two commercial glycols were used in the study. The tests indicate that both glycols provide the metals tested with good corrosion protection. Glycol with conventional inhibitor chemicals prevents corrosion of aluminum even with extensive anodic polarization. Although initiation of pitting could be observed in the same conditions with an inhibitor system based on organic acid technology, it is not very likely to have galvanic corrosion on aluminum by dissolved and deposited copper in automotive coolant systems.

This paper reviews recent work on high power and energy density batteries, which are being studied as possible electrochemical energy storage devices for electric vehicle power-plants. The requirement of high energy density for vehicle applications leads to the selection of battery systems made up of light, highly reactive metals found in the upper left-hand corner of the periodic table for one electrode and the light oxidizers found in the top right-hand corner of the periodic table for the other electrode. Many of these reactive materials will react with water and, hence, water based electrolytes cannot be used in these systems. The parameters relevant to achieving high energy, high power batteries are discussed and several systems presently being studied are reviewed, with particular emphasis on the Li-Cl2M battery.

This work focuses on the electrochemical behavior and corrosion performance of a tri-layer aluminum brazing sheet AA7072/3003/4343 in OY synthetic water. Post-brazed tri-layer sheet samples from four different brazing temperature cycles were subjected to the immersion corrosion test in OY synthetic water for 30 days at 88 ± 2°C to investigate the effect of brazing temperature and zinc diffusion on the corrosion performance of the material. Electrochemical measurement method was also used for examining the corrosion potentials and the galvanic corrosion currents for AA7072, AA3003 and AA4343 both before and after brazing in OY water. The results show that the zinc-containing AA7072 sacrificial layer corroded preferentially during the immersion corrosion tests in OY water.

There are two techniques being considered for carbon dioxide (CO2) removal and concentration for application in a regenerable Environmental Control and Life Support Systems (EC/LSS) aboard the projected Space Station. One uses the continuous Electrochemical Depolarized CO2 Concentration (EDC) technique while the second uses the cyclic absorption and desorption (with steam) from an amine resin bed. While the technologies involved with these techniques are substantially different, each must interface with other elements of a regenerable EC/LSS. This paper presents a comparison of the two competing technologies and includes the design and sizing of the respective subsystems for a Space Station application. The analysis includes identification of assumptions and groundrules with particular attention given to defining subsystem boundaries.

Significant research has been underway for many years to develop technologies to electrochemically power vehicles with limited success. Unfortunately, most technologies fail to achieve theoretical performance and/or are prohibitively too expensive for mass marketed vehicles. Most of the issues with electrochemical technologies can ultimately be attributed to materials issues, whether it is cost, durability, or activity. A broad examination of potential electrochemical technologies is provided identifying key materials issues with each. Included are the results of recent research involving lithium-oxygen batteries. The observations from this research have identified the electrochemical product, lithium peroxide, and its properties to be the most pressing material issue for lithium-oxygen battery. A future research vision is proposed counter to the current research trend of electrocatalyst/electrolyte development.