Splash Splat to Disk Splat Transition Behavior in Plasma-Sprayed Metallic Materials

A variety of metallic powder particles were thermally sprayed onto the mirror polished metallic substrate surface and the effect of both substrate temperature and ambient pressure on the flattening behavior of the particle was systematically investigated. In the flattening behavior of the sprayed particle onto the substrate surface, critical conditions were recognized both in the substrate temperature and ambient pressure. That is, the flattening behavior changed transitionally on that critical temperature and pressure range, respectively. A transition temperature, T _t, and transition pressure, P _t, were defined and introduced, respectively for those critical conditions. The fact that the dependence of both transition temperature and transition pressure on the sprayed particle material had similar tendency indicated that the wetting of the substrate by the molten particles seemed to be a domination in the flattening. Three-dimensional transition curvature by combining both transition temperature and transition pressure dependence was proposed as a practical and effective controlling principle of the thermal spray process. This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain Montavon, Ed., ASM International, Materials Park, OH, 2007.     

Simultaneous removal of acetaldehyde,ammonia and hydrogen sulphide from air by active carbon impregnated with p-aminobenzoic acid,phosphoric acid and metal compounds

Simultaneous removal of acetaldehyde, ammonia, and hydrogen sulphide from air by the impregnated active carbon was studied at 25C. p-Aminobenzoic acid (PABA), phosphoric acid (H₃PO₄), and metal compound such as copper (II) chloride dihydrate (CuCl₂·2H₂O), copper (II) nitrate trihydrate (Cu(NO₃)₂·3H₂O), and potassium iodide (KI) were investigated as impregnation ingredients. Acetaldehyde and ammonia were simultaneously removed from air by the active carbon impregnated with PABA and H₃PO₄. The removal was found to be made mainly through chemical reaction. Acetaldehyde, ammonia, and hydrogen sulphide were simultaneously removed from air by the active carbon impregnated with PABA, H₃PO₄, and metal compound such as CuCl₂·2H₂O, Cu(NO₃)₂·3H₂O, and KI.     

A near-field-sensing transceiver for intrabody communication based on the electrooptic effect

This paper describes a near-field-sensing transceiver for intrabody communication, in which the human body is the transmission medium. The key component of the transceiver is an electric-field sensor implemented with an electrooptic crystal and laser light. This sensor is suitable for detection of the small and unstable electric fields produced by the human body because it has extremely high input impedance. This transceiver enables IEEE 802.3 half-duplex communication of 10 Mb/s through a person's body in an operating range of about 150 cm between the hands. The packet error rate of 0.04% is obtained at packet size of 1070 octet. This paper explains the configuration and performance of the transceiver and presents results of a communication test.     

Challenges Upon Reactive Plasma Spray Nitriding: Al Powders and Fabrication of AlN Coatings as a Case Study

Reactive plasma spraying (RPS) is a promising technology for the in situ formation of several ceramic coatings. The focus of this paper is to summarize the state of our current knowledge about the RPS process and using the nitriding of Al particles and the fabrication of aluminum nitride coatings, as a case study. The aspects and challenges in this process such as the influence of the plasma power, in-flight time, particle size, nitriding mechanism, splat morphology, in-flight particle diagnostics, N₂ plasma gas, and the feeding rate on the RPS process are analyzed and discussed.     

Development of Ultra Low Field Nuclear Magnetic Resonance Imaging System Using HTS rf SQUID

We constructed and studied an ultra low-field nuclear magnetic resonance imaging system using a HTS rf SQUID and room-temperature coils. We recorded the free induction decay signals of ¹H by employing a measuring field, B _m, of 44.8???T and a polarizing field, B _p, of 36.8?mT; in the presence of ? B _Z /? z and ? B _Z /? y gradients of the order of 0.8???T/m, we were able to obtain a quasi two-dimensional 4-pixels image of a simple water phantom.     

TEM,XPS and SIMS Analyzes on Grain Boundary of Lanthanum Chromites

The morphological characteristics, chromium valence state, and cation transport in the vicinity of grain boundary in La_1-xCa_xCrO₃ were investigated by using TEM/EDS, XPS and SIMS techniques. The width of grain boundary was around 1 nm where anomalous enrichment of calcium was observed. Higher valence state of chromium such as Cr⁶⁺(d⁰) was detected in the grain boundaries whereas Cr³⁺(d³) and Cr⁴⁺(d²) were dominant in the bulk. Very fast interdiffusion of alkaline earths was observed in the Sr²⁺-La_0.75Ca_0.25CrO₃ system. All observed phenomena were correlated by assuming the A-site vacancy which may be induced by the formation of Cr⁶⁺ at grain boundaries.     

The effects of VDT work on the regulation of hemodynamics compared with aging

Urinary excretions of aldosterone, blood pressure, and heart rate were examined for three age groups of volunteers searching for target words on VDT for two hours. Aldosterone excretion did not change in the young and middle-aged groups, but increased in the elderly group. Blood pressure decreased midway through the work in the young group, and increased during the work in the middle-aged and elderly groups. Aldosterone excretion did not increase during hard-copy work or during VDT work with large letters, but increased during VDT work with small letters. During VDT work with both large and small letters, blood pressure increased. During hard-copy work, neither blood pressure nor heart rate changed, although blood pressure increased after the work. These data suggest that the sympathetic nervous activation represented by the increases in aldosterone excretion and blood pressure occurred definitively during VDT work with small letters under the conditions of this study. It is also suggested that this effect is enhanced by aging.     

Hydrolysis behavior of aluminum nitride in various solutions

The AlN powder was immersed in deionized water, HCl aq, NaOH aq and H₃PO₄ aq to investigate their hydrolysis behavior at 283 to 373 K. The pH of the solutions were not varied at the initial stage in the case of deionized water, and they increased abruptly after the incubation time with evolution of NH₃. Time until the evolution of NH₃ decreased with increasing temperature. The hydrolysis at the higher temperature was different from at the lower. Below 351 K a crystalline bayerite was produced on the surface of AlN particle, while a crystalline boehmite was produced at higher than 351 K. The AlN powder was hydrolyzed more efficiently in HCl aq and NaOH aq compared with in the deionized water. While, H₃PO₄ aq restrained hydrolysis of AlN powder.     

A simple method for measuring the relative permittivity of printedcircuit board materials

This paper presents a simple method to measure the relative permittivity of glass-epoxy printed circuit boards (PCBs). In this method, the relative permittivity as a function of frequency is measured using an actual PCB. In order to estimate the relative permittivity, the reflection coefficient is measured with a network analyzer. The relative permittivity is calculated by observing the frequencies of the resonant cavity modes. We show that the relative permittivity of an FR-4 sample decreases from 4.3 to 4.2 at frequencies from 300 MHz to 2 GHz