The Experts below are selected from a list of 4512 Experts worldwide ranked by ideXlab platform
Paul D. Fleischauer - One of the best experts on this subject based on the ideXlab platform.
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The Influence of Steel Surface Chemistry on the Bonding of Lubricant Films
1992Co-Authors: S. V. Didziulis, Michael R. Hilton, Paul D. FleischauerAbstract:Abstract : Virtually all moving mechanical assemblies on spacecraft contain steel components that must be effectively lubricated to ensure optimum performance and long life. This report details the surface chemical composition of 440C stainless steel and its interaction with two lubricant species: the solid lubricant MoS2 and the liquid lubricant extreme pressure (EP) additive, lead naphthenate (Pbnp). X-ray photoelectron spectroscopy (XPS) studies show that the 440C surface has a layered oxide structure following polishing and Solvent Cleaning; a 2.5 nm thick iron oxide layer exists on top of a thinner 1.5 nm chromium oxide underlayer. A region of high metal carbide concentration is present at the chromium oxide-bulk steel interface. Therefore, a layer of iron oxide (not the corrosion barrier formed by the chromium oxide layer) is the top surface layer with which lubricant species interact under conditions of low stress. The surface chemical composition of 440C can be altered by chemical or physical means. Chemical treatments such as acidic and alkaline etches selectively remove the iron oxide overlayer, leaving behind a surface enriched in chromium oxide. Furthermore, the alkaline treatment proved to be more controllable, while the acid treatment can cause surface damage by breaking through the corrosion barrier and severely oxidizing the bulk steel. Extreme Pressure Additive, Molybdenum Disulfide, 440C Stainless Steel, Solid Lubrication, Lead Naphthenate, Surface Chemistry.
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Chemistry of the extreme-pressure lubricant additive lead naphthenate on steel surfaces
Langmuir, 1991Co-Authors: Stephen V. Didziulis, Paul D. FleischauerAbstract:Abstract : The adsorption and chemical reactivity of the extreme pressure (EP) oil additive lead naphthenate (Pbnp) on steel surfaces is examined with X-ray photoelectron spectroscopy. In addition, the chemical compositions of AISI 440C and 52100 steel surfaces are studied as a function of sample Cleaning treatment, including Solvent Cleaning, and treatments with acidic and basic solutions. At room temperature, Pbnp is shown to physisorb on the iron oxide over-layer present on both steel surfaces following Solvent Cleaning. A chemisorbed form of Pbnp is characterized by Pb 4f peaks chemically shifted by 0.3 to 0.4 eV to lower binding energy and significantly lower intensity of the C ls feature associated with the Pbnp carboxylate group. This form of Pbnp is observed on acid- and base-pretreated surfaces that lose their iron oxide overlayers. The chemisorbed Pbnp surface species is also observed when the steel surfaces are scratched while being immersed in the Pbnp solution. When the Pbnp-treated steel surfaces are heated to simulate the EP conditions for which Pbnp is used, most of the Pbnp on the oxide-covered surfaces desorbs. In addition, metallic Pb is readily formed on the scratched surfaces and whenever significant amounts of metallic Fe are present. These results point to two possible modes of boundary protection: chemisorbed Pbnp under mild wear conditions and a layer of metallic Pb under severe wear conditions. Lubrication, Steel, Oil Additives, Surface Chemistry.
B Kasemo - One of the best experts on this subject based on the ideXlab platform.
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Morphological and chemical characterization of microfabricated fibres for biological applications
Journal of Materials Science: Materials in Medicine, 1997Co-Authors: J Gold, B KasemoAbstract:Monodisperse fibres and particulates of different materials with controllable three-dimensional shape, size and chemical composition are of interest in research on toxic respirable fibres as well as wear debris around orthopaedic implants. We have previously demonstrated the production of well-controlled, metal and oxide microfabricated fibres having dimensions 0.1 to 10 μm. While our previous results focused on how controlled fibres can be prepared by microfabrication methods, this paper evaluates property–production relationships for microfabricated fibres. Here we have briefly reviewed the production of 0.1 μm×0.5 μm×10 μm microfabricated fibres made by electron beam lithography from evaporated titanium or silicon oxide films using a double lift-off method. We have also analysed the properties of these fibres with respect to morphology and chemical composition, and how they are affected by variations in the production process. Two different solution types have been used to place fibres into liquid suspension and to clean and sterilize them for biological testing. One method involves the use of organic Solvents; the other a hydroxide solution and water. While fibre dimensions appear to be material-specific, differences can be corrected for by compensation of the size of the lithographic pattern. Similarly the crystallinity of fibres is material-specific, as is to be expected of evaporated thin films, but should be possible to modify by varying deposition parameters or heat treating, for example. Of the Cleaning methods used, the one using an aqueous hydroxide solution is preferred over Solvent Cleaning, as it is easier to perform and appears to be more effective at removing resist from the fibre suspension.
Xiao Ling Zhao - One of the best experts on this subject based on the ideXlab platform.
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preparation and characterization of steel surfaces for adhesive bonding
Journal of Composites for Construction, 2013Co-Authors: Dilum Fernando, J G Teng, Xiao Ling ZhaoAbstract:AbstractIn fiber-reinforced polymer (FRP) strengthened steel structures, debonding of the bonded FRP reinforcement from the steel substrate may result from adhesion failure at the steel/adhesive interface or the FRP/adhesive interface, cohesion failure in the adhesive, or a combination of these two modes. Of these failure modes, cohesion failure in the adhesive is the preferred mode of failure as it facilitates the development of a design theory based on the adhesive properties; the other two failure modes should be avoided if at all possible. This paper presents a systematic experimental study to identify a surface-adhesive combination that will avoid adhesion failure at the steel/adhesive interface. Different steel surface preparation methods, including Solvent Cleaning, hand grinding, and grit blasting, and different commonly used adhesives were examined in the study. Surface characterization using three key parameters (namely surface energy, surface chemical composition, and surface roughness and topo...
John B. Durkee - One of the best experts on this subject based on the ideXlab platform.
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Open-Top Cleaning Equipment for Vapor Degreasing
Cleaning with Solvents: Methods and Machinery, 2014Co-Authors: John B. DurkeeAbstract:In references about Solvent Cleaning, the focus tends to be all about Solvents and not about the Cleaning machines in which they are used, and the processes in which they are implemented within those machines. This book is that content. It's about Cleaning machines and processes so that the various Cleaning Solvents can be successfully used to clean parts.
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Solvent Cleaning: Questions and Answers
Cleaning with Solvents, 2014Co-Authors: John B. DurkeeAbstract:The content of this book is mostly scientific or technical, where the author's opinion is expressed only sparsely. But the basis for management decisions about Cleaning must be based on more than just technology. It also must be based on local knowledge and actual experience. While local knowledge is outside the scope of this book's charter, the latter is not.
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Chapter 8 – Solvent Azeotropes
Cleaning with Solvents, 2014Co-Authors: John B. DurkeeAbstract:For most users who do vapor degreasing of surfaces, Solvent Cleaning has undergone a profound change over the last decade or so. The motive forces for this change have been those categorized by the administrative name SHE (Safety, Health, and Environmental). The change produced by those forces has been to limit applications for Solvent Cleaning because of the absence of Solvents that meet practical, economic and SHE requirements. This chapter is about a reaction to those forces: Replacement of single Solvents over which there are legitimate SHE concerns with binary mixtures of other single Solvents which don’t generate those SHE concerns. Specifically, the mixtures covered in this chapter are binary azeotropes. The reason for considering binary azeotropes is that their performance properties can sometimes match those of single Solvents which generate SHE. concerns without engendering those concerns!
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Stabilization of Solvents
Cleaning with Solvents, 2014Co-Authors: John B. DurkeeAbstract:The example about choices in this chapter is of unwanted degradation of a Cleaning Solvent reacting with its environment and whether or not that degradation can be tolerated and managed with Solvent Cleaning technology, or ignored by choosing another Cleaning technology.
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The VOC Exemption Game
Cleaning with Solvents, 2014Co-Authors: John B. DurkeeAbstract:This chapter is about the Holy Grail of Solvent Cleaning in the US: the exemption of Solvents from Volatile Organic Compound (VOC) status. Through their votes for (or against) and communications with their elected officials, US citizens can exert pressure on government regulators to prevent pollution.
Tobin J Marks - One of the best experts on this subject based on the ideXlab platform.
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anode interfacial tuning via electron blocking hole transport layers and indium tin oxide surface treatment in bulk heterojunction organic photovoltaic cells
Advanced Functional Materials, 2010Co-Authors: Alexander W Hains, Jun Liu, Alex B F Martinson, Michael D Irwin, Tobin J MarksAbstract:The effects of anode/active layer interface modification in bulk-heterojunction organic photovoltaic (OPV) cells is investigated using poly(3,4-ethylenedioxythiophene) : p o l y(st y rene sulfonate) (PEDOT:PSS) and/or a holetransporting/electron-blocking blend of 4,4'-bis[(p-trichlorosilylpropylphenyl)-phenylamino]biphenyl (TPDSi 2 ) and poly[9,9-dioctylfluorene-co-N-[4-(3-methylpropyl)]-diphenylamine] (TFB) as interfacial layers (IFLs). Current-voltage data in the dark and AM1.5G light show that the TPDSi 2 :TFB IFL yields MDMO-PPV:PCBM OPVs with substantially increased open-circuit voltage (V oc ), power conversion efficiency, and thermal stability versus devices having no IFL or PEDOT:PSS. Using PEDOT:PSS and TPDSi 2 :TFB together in the same cell greatly reduces dark current and produces the highest V oc (0.91 V) by combining the electron-blocking effects of both layers. ITO anode pre-treatment was investigated by X-ray photoelectron spectroscopy to understand why oxygen plasma, UV ozone, and Solvent Cleaning markedly affect cell response in combination with each IFL. O 2 plasma and UV ozone treatment most effectively clean the ITO surface and are found most effective in preparing the surface for PEDOT:PSS deposition; UV ozone produces optimum solar cells with the TPDSi 2 :TFB IFL. Solvent Cleaning leaves significant residual carbon contamination on the ITO and is best followed by O 2 plasma or UV ozone treatment.
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Anode Interfacial Tuning via Electron-Blocking/Hole-Transport Layers and Indium Tin Oxide Surface Treatment in Bulk-Heterojunction Organic Photovoltaic Cells
Advanced Functional Materials, 2010Co-Authors: Alexander W Hains, Jun Liu, Alex B F Martinson, Michael D Irwin, Tobin J MarksAbstract:The effects of anode/active layer interface modification in bulk-heterojunction organic photovoltaic (OPV) cells is investigated using poly(3,4-ethylenedioxythiophene) : p o l y(st y rene sulfonate) (PEDOT:PSS) and/or a holetransporting/electron-blocking blend of 4,4'-bis[(p-trichlorosilylpropylphenyl)-phenylamino]biphenyl (TPDSi 2 ) and poly[9,9-dioctylfluorene-co-N-[4-(3-methylpropyl)]-diphenylamine] (TFB) as interfacial layers (IFLs). Current-voltage data in the dark and AM1.5G light show that the TPDSi 2 :TFB IFL yields MDMO-PPV:PCBM OPVs with substantially increased open-circuit voltage (V oc ), power conversion efficiency, and thermal stability versus devices having no IFL or PEDOT:PSS. Using PEDOT:PSS and TPDSi 2 :TFB together in the same cell greatly reduces dark current and produces the highest V oc (0.91 V) by combining the electron-blocking effects of both layers. ITO anode pre-treatment was investigated by X-ray photoelectron spectroscopy to understand why oxygen plasma, UV ozone, and Solvent Cleaning markedly affect cell response in combination with each IFL. O 2 plasma and UV ozone treatment most effectively clean the ITO surface and are found most effective in preparing the surface for PEDOT:PSS deposition; UV ozone produces optimum solar cells with the TPDSi 2 :TFB IFL. Solvent Cleaning leaves significant residual carbon contamination on the ITO and is best followed by O 2 plasma or UV ozone treatment.