Ni--P coatings are extensively employed in engineering, owing to their mechanical and tribological properties which confer protection against corrosion and wear. Classically, such deposits can have a ...thickness of <500 μm, although there is a trend to thinner coatings to achieve faster deposition and lower costs. Depending on their composition and structure, as-plated deposits demonstrate good mechanical, tribological and electrochemical features, catalytic activity but also beneficial magnetic characteristics. Following thermal treatment, the hardness of Ni--P metal deposits can approach or exceed that of hard Cr coatings. This paper provides a general survey of research on the electrodeposition of NiP binary alloy coatings. Proposed phosphorus incorporation mechanisms, Ni--P alloy microstructure before and after thermal treatment. Mechanical, tribological, corrosion, catalytic and magnetic properties are considered, as are the key process variables influencing the phosphorus content of deposits and the roles of the major electrolytic bath constituents. The merits of employing pulse plating and fabrication of newer (layered and functionally graded) structures are concisely explored. Interaction of four aspects: substrate state, electrolyte composition, process conditions and deposit properties is seen to be important during electrodeposition of Ni--P alloys; areas deserving further study are identified.
The use of two-dimensional gas chromatography hyphenated with vacuum ultraviolet absorbance spectroscopy (GC×GC-VUV) is constantly finding new applications. To qualitatively and quantitively exploit ...the information obtained with this type of analysis, suitable softwares are needed. However, to date, existing multidimensional chromatography softwares are not fully adapted to this type of data and offer only limited processing capabilities. Moreover, other solutions often rely on homemade programs that are not accessible to new users. For these reasons, several data processing modules for GC×GC-VUV data were developed and were integrated into the free access plug im! software (https://www.plugim.fr/). The usage guidelines and functionalities of the proposed modules are described, and several video tutorials are supplied. The proposed modules allow to visualise and preprocess GC×GC-VUV data. The extraction of spectra for user-designed template zones is also made possible which enables their further use for both quantification and spectral decomposition. These tools result in more sensitive methods thanks to the increase of the signal-to-noise ratio through application of adapted data preprocessing.
•Data processing modules dedicated to all three possible types of GC×GC-VUV data (1D, 2D and full 3D data) were contributed.•Adapted GC×GC-VUV data preprocessing methods allowing to significantly improve signal-to-noise ratio were integrated.•Identification template creation and extraction of absorbance spectra from all template zones was made possible.•Easy mapping of sample composition trough combination of several ‘spectral filters’ was proposed.
The conventional reverse fill/flush flow modulation for comprehensive two‐dimensional gas chromatography requires a bleed capillary column to be connected to the outlet of the modulator channel. The ...purpose of this capillary, which does not contain the stationary phase, is to provide pressure resistance to the modulator channel flow. In this way, the desired modulator volumetric flow can be achieved, and channel over‐filling can be avoided. Normally, the length and the internal diameter of the bleed capillary are chosen so as to obtain the modulator flow that is close to the flow of the first separation column. Thus, for any chosen set of chromatographic conditions, the required dimensions of the bleed capillary can be completely different, making the two‐dimensional gas chromatography method development tedious and generating additional costs in consumables and analyst time. In this work, a tuneable pressure source generating a suitable backpressure was used instead of the fixed bleed capillary which has the advantage of the possibility to freely adapt the pressure resistance and generate the required modulator channel flow for any conditions. This set‐up has been evaluated and compared in terms of the impact on the modulation performance to the set‐up involving a fixed bleed capillary demonstrating comparable performance.
Ni-P coatings produced by electrodeposition have important mechanical, tribological and electrochemical properties. They can also exhibit catalytic activity and beneficial magnetic behaviour. With ...subsequent thermal treatment, the hardness of such Ni-P coatings can approach or exceed that of hard Cr coatings. Electrochemical codeposition of homogeneously dispersed second phase particles within the Ni-P matrix can enhance deposit properties and meet the challenging demands on modern engineering coatings. A general overview of research work on the electrodeposition of Ni-P composite coatings containing included ceramic or solid lubricant particles is provided. Advances in research into Ni-P composite layers reinforced by SiC, B4C, WC, Al2O3, SiO2, TiO2, CeO2, MWCNT, MoS2, WS2, TiN, hexagonal BN, PTFE and their combinations are considered. Major models proposed for the codeposition of particles, the influence of bath hydrodynamics and control of operational parameters are illustrated by examples. Important trends are highlighted and opportunities for future R & D are summarised.
NiP coatings produced by electrodeposition have important mechanical, tribological and electrochemical properties. They can also exhibit catalytic activity and beneficial magnetic behaviour. With ...subsequent thermal treatment, the hardness of such NiP coatings can approach or exceed that of hard Cr coatings. Electrochemical codeposition of homogeneously dispersed second phase particles within the NiP matrix can enhance deposit properties and meet the challenging demands on modern engineering coatings. A general overview of research work on the electrodeposition of NiP composite coatings containing included ceramic or solid lubricant particles is provided. Advances in research into NiP composite layers reinforced by SiC, B4C, WC, Al2O3, SiO2, TiO2, CeO2, MWCNT, MoS2, WS2, TiN, hexagonal BN, PTFE and their combinations are considered. Major models proposed for the codeposition of particles, the influence of bath hydrodynamics and control of operational parameters are illustrated by examples. Important trends are highlighted and opportunities for future R & D are summarised.
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•The electrodeposition of Ni-P coatings containing included particles is reviewed.•Substrate, reactions, bath composition/additives and flow are important.•Developments include pulse plating and nanostructured particle deposits.•Expanding application areas include tribology and corrosion protection.•Aspects deserving further R & D are identified.
NiP coatings are extensively employed in engineering, owing to their mechanical and tribological properties which confer protection against corrosion and wear. Classically, such deposits can have a ...thickness of <500 μm, although there is a trend to thinner coatings to achieve faster deposition and lower costs. Depending on their composition and structure, as-plated deposits demonstrate good mechanical, tribological and electrochemical features, catalytic activity but also beneficial magnetic characteristics. Following thermal treatment, the hardness of NiP metal deposits can approach or exceed that of hard Cr coatings. This paper provides a general survey of research on the electrodeposition of NiP binary alloy coatings. Proposed phosphorus incorporation mechanisms, NiP alloy microstructure before and after thermal treatment. Mechanical, tribological, corrosion, catalytic and magnetic properties are considered, as are the key process variables influencing the phosphorus content of deposits and the roles of the major electrolytic bath constituents. The merits of employing pulse plating and fabrication of newer (layered and functionally graded) structures are concisely explored. Interaction of four aspects: substrate state, electrolyte composition, process conditions and deposit properties is seen to be important during electrodeposition of NiP alloys; areas deserving further study are identified.
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•The electrodeposition of NiP alloy coatings and their use are reviewed.•Substrate, electrolyte, process conditions and deposit properties are important.•Electrode reactions, bath composition and additives are considered.•Developments include pulse plating, layered and multifunctional layers.•Aspects deserving further R & D are identified.
Gas oils (GOs) analysis is essential for production process control, in order to meet quality standards, to render these products safer for the environment, and to support research for alternative ...fuels. GOs quantitative analysis can be commonly achieved by employing two-dimensional comprehensive gas chromatography with flame ionization detection (GC × GC-FID) in combination with identification templates. However, in order to perform quantification for families which coelute in GC × GC analysis (e.g., naphthenes/olefins or polynaphthenes/monoaromatics), prefractionation of gas oil before GC × GC analysis is necessary. Recent introduction of the vacuum ultraviolet (VUV) detector has offered new possibilities in GOs analysis, as this detector can discern between the majority of hydrocarbon families thus possibly rendering the gas oil prefractionation unnecessary. Additionally, it can perform quantification according to Beer–Lambert’s law provided that VUV relative response factors (RRFs) are known. The purpose of this work is to report, for the first time, VUV RRFs for numerous hydrocarbons in GOs (∼160) according to their family and their carbon number, permitting to perform their direct quantification without the necessity of GO prefractionation. VUV RRFs were measured by using a GC × GC-VUV/FID dual detection setup in which FID was employed as a quantitative reference. In order to obtain VUV RRFs representative for any gas oil, a set of 14 GOs with different origins was employed. Both VUV RRFs averaged in the 125–240 nm range and spectral VUV RRFs (reference spectra) were obtained. It was demonstrated that VUV RRFs were similar between employed GOs allowing their universal use. Obtained RRFs were used to perform hydrocarbons quantification for a light cycle oil (LCO) by GC × GC-VUV, with olefins and naphthenes being quantified through spectral decomposition. Good comparability with results obtained by prefractionation was observed demonstrating the great interest of the GC × GC-VUV approach for the detailed and rapid analysis of hydrocarbons in gas oils.
Abstract
Modulation is the key element of the comprehensive 2D gas chromatography separation. Forward fill/flush flow modulation is cost effective, robust and suitable for analysis of a wide range of ...samples. Even though this modulation system is well known, studies regarding its optimization are sparse. In this work, based on hundreds of experiments involving multiple column sets and modulation conditions, an approach was proposed that permits to facilitate the choice of the forward fill/flush flow modulation parameters. A score function was developed that allows to predict the forward fill/flush flow modulation process efficiency as judged by the modulated peak shape. The score function was based on the physical rules for optimized and quantitative forward fill/flush flow modulation proposed in our previous work, which state that the sum of the fill and flush modulation distances should be close to the modulation channel length and that the ratio of the flush and fill distances should be sufficiently high for efficient channel flushing. The score function was embedded in a freely available tool in the form of a forward fill/flush flow modulation calculator, which allows the user either to quickly check the relevancy of the modulation operating conditions or to obtain a suggestion for optimal modulation parameters.
•Quantitative performance of forward fill/flush modulation is investigated in detail.•Parameters influencing efficiency of the modulation are delineated.•Relation between modulated peak shape and ...analyte quantitation is explored.•Role of the modulation fill and flush distances is explored through appropriate calculations.
GC × GC is an advanced separation technique allowing to achieve quantitative and qualitative characterization of complex samples. In order to perform two-dimensional separation, the system must provide suitable peak modulation which will direct short impulses of first column flow towards the second column. Forward fill/ flush differential flow modulation is a cost effective and no cryogen requiring approach which allows modulation over a wide range of analytes with very different boiling points. However, optimization of the flow modulation process can be difficult to understand and quantification performance might be compromised if the parameters of the modulation process are not properly set. Modulated peak shape can be a good indication of the efficiency of the modulation process, however it is not sufficient to guarantee good quantification. Different average velocities in the beginning and the end of the thermally programmed GC run may cause different efficiency of the modulation process in various parts of the chromatogram. The purpose of this work is to investigate quantitative performance of the forward/fill flush modulation and delineate parameters that determine the effectiveness of the modulation process and its ability to properly reflect the quantitative composition of the investigated sample.
Gas chromatography vacuum ultraviolet spectroscopy: A review Lelevic, Aleksandra; Souchon, Vincent; Moreaud, Maxime ...
Journal of separation science,
January 2020, 2020-Jan, 2020-01-00, 20200101, 2020-01, Letnik:
43, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Accelerated technological progress and increased complexity of interrogated matrices imposes a demand for fast, powerful, and resolutive analysis techniques. Gas chromatography has been for a long ...time a ‘go‐to’ technique for the analysis of mixtures of volatile and semi‐volatile compounds. Coupling of the several dimensions of gas chromatography separation has allowed to access a realm of improved separations in the terms of increased separation power and detection sensitivity. Especially comprehensive separations offer an insight into detailed sample composition for complex samples. Combining these advanced separation techniques with an informative detection system such as vacuum ultraviolet spectroscopy is therefore of great interest. Almost all molecules absorb the vacuum ultraviolet radiation and have distinct spectral features with compound classes exhibiting spectral signature similarities. Spectral information can be ‘filtered’ to extract the response in the most informative spectral ranges. Developed algorithms allow spectral mixture estimation of coeluting species. Vacuum ultraviolet detector follows Beer–Lambert law, with the possibility of calibrationless quantitation. The purpose of this article is to provide an overview of the features and specificities of gas chromatography–vacuum ultraviolet spectroscopy coupling which has gained interest since the recent introduction of a commercial vacuum ultraviolet detector. Potentials and limitations, relevant theoretical considerations, recent advances and applications are explored.
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