Rola obróbki plazmą MV na odporność korozyjną stali stopowych

Obróbkę powierzchni wysokostopowych stali chromowo-niklowej typu duplex S32404 i austenitycznej S32615 przeprowa- dzono poprzez węgloazotowanie przy użyciu techniki próżniowej z mikrofalowym wspomaganiem plazmowym o częstotliwości 2.45GHz i mocy generatora 350W. Zastosowano reaktywną mieszaninę gazową zawierającą CH4 i N2 w warunkach niskiego ciśnienia 0.2 Tr. przy niskiej temperaturze 400°C. Oceniono wpływ składu chemicznego i struktury stopów na tworzącą się war- stwę wierzchnią podczas obróbki. Strukturę powierzchni analizowano za pomocą rentgenowskiej spektroskopii fotoelektronów (XPS). Odporność korozyjną próbek określano na podstawie krzywych polaryzacyjnych LSV w 3% roztworze chlorku sodu przy temperaturze 37°C. Powierzchnie stali poddane obróbce wykazały wyższą skłonność do pasywacji w oraz podwyższały odporność na korozję wżerową w porównaniu z powierzchniami niemodyfikowanymi.Two stainless steels (S32404 duplex and S32615 austenitic) were subject to the carbon/nitrogen plasma treatment to examine the role of alloy composition and structure in the behavior of surface during modification. The modification process was performed in the electron cyclotron resonance (ECR) micro wave plasma system, with the frequency of 2.45 GHz and the generator power of 350 W, and with the use of reactive gas mixtures containing CH4 and N2, at the low temperature of 400°C and under pressure of 0.2Tr. The treated surface was analyzed by means of X-ray photoelectron spectroscopy (XPS). The corrosion resistance of the samples was determined on the basis of LSV polarization curves in 3% sodium chloride solution at 37°C. The treated steel surfaces showed a higher tendency for passivation and higher pitting corrosion resistance compared to the non-modified surfaces

Morphology and electrical conductivity of carbon nanocoatings prepared from pyrolysed polymers

Conductive carbon nanocoatings (conductive carbon layers-CCL) were formed on \alpha-Al_{2}O_{3} model support using three different polymer precursors and deposition methods. This was done in an effort to improve electrical conductivity of the material through creating the appropriate morphology of the carbon layers. The best electrical properties were obtained with use of a precursor that consisted of poly-N-vinylformamide modified with pyromellitic acid (PMA). We demonstrate that these properties originate from a specific morphology of this layer that showed nanopores (3-4 nm) capable of assuring easy pathways for ion transport in real electrode materials. The proposed, water mediated, method of carbon coating of powdered supports combines coating from solution and solid phase and is easy to scale up process. The optimal polymer carbon precursor composition was used to prepare conductive carbon nanocoatings on LiFePO_{4} cathode material. Charge-discharge tests clearly show that C/LiFePO_{4} composites obtained using poly-N-vinylformamide modified with pyromellitic acid exhibit higher rechargeable capacity and longer working time in a battery cell than standard carbon/lithium iron phosphate composites

Funkcjonalizacja mezoporowatej krzemionki SBA-15 w wyniku szczepienia poliwinyloaminy na powierzchni modyfikowanej grupami epoksydowymi

Mesoporous SBA-15 silica was modified by grafting of 3-glycidoxypropyltrimethoxysilane (GPTMS). An influence of GPTMS/SBA-15 mass ratio used during this pre-functionalization step on the real amount of epoxy-silane grafted on the SBA-15 surface was studied by thermogravimetry and elemental analysis. The pre-functionalized SBA-15 was subsequently used to attach polyvinylamine (PVAm) chains by the opening of oxirane rings and the formation of bonds with NH2 groups from PVAm. The yield of this process was determined. Furthermore, SEM (scanning electron microscopy), DRIFT (diffuse reflectance infrared Fourier transform spectroscopy) and XPS (X-ray photoelectron spectroscopy) as well as zeta potential measurements were applied to observe the changes in the chemical composition of SBA-15 surface and morphology of the synthesized materials. Various types of organic functionalities present on the modified SBA-15 were identified and analyzed quantitatively.Powierzchnię mezoporowatej krzemionki SBA-15 zmodyfikowano na drodze szczepienia 3-glicydoksypropylotrimetoksysilanu (GPTMS). Z wykorzystaniem metod analiz elementarnej oraz termograwimetrycznej badano wpływ stosunku masowego GPTMS/SBA-15 zastosowanego we wstępnej modyfikacji na rzeczywistą zawartość wprowadzonych na powierzchnię krzemionki grup epoksydowych. Do powierzchni zmodyfikowanego SBA-15 przyłączono następnie łańcuchy poliwinyloaminy (PVAm) w wyniku reakcji otwierania pierścieni oksiranowych połączonej z utworzeniem wiązań z grupami NH2 pochodzącymi od PVAm. Określono wydajność tego procesu. Badania SEM (skaningowej mikroskopii elektronowej), DRIFT (spektroskopii odbicia rozproszonego w podczerwieni), XPS (spektroskopii fotoelektronów) oraz pomiary potencjału zeta pozwoliły na ocenę zmian składu chemicznego powierzchni SBA-15 oraz morfologii zsyntetyzowanych materiałów. Zidentyfikowano oraz oznaczono ilościowo różne rodzaje grup funkcyjnych obecnych na powierzchni modyfikowanej krzemionki SBA-15

An influence of thermal treatment conditions of hydrotalcite-like materials on their catalytic activity in the process of N2ON_2O decomposition

Hydrotalcite-like materials containing apart from magnesium and aluminum also copper, cobalt, nickel, and iron were prepared by a co-precipitation method. Thermal transformations of hydrotalcite-like materials were studied by thermal analysis methods as well as XRD, UV-vis-DRS, and XPS measurements of the samples calcined at various temperatures (600, 700, and 800 {\textdegree}C). Calcined hydrotalcites, especially those containing cobalt and copper, were found to be active and selective catalysts of N2O decomposition. It was shown that an increase in the calcination temperature significantly activated the Co-containing catalysts. Promotion of the samples with potassium resulted in activation of the hydrotalcite-based catalysts

SBA-15 mesoporous silica modified with rhodium by MDD method and its catalytic role for N2ON_2O decomposition reaction

SBA-15 mesoporous silicas modified with rhodium were studied as catalysts for the N2O decomposition reaction. Rhodium was deposited on SBA-15 by the Molecular Designed Dispersion (MDD) method using Rh(acac)3 as a precursor of active phase. The same method was used for the deposition of Cu, Fe, Al and Ti. The SBA-15 support modified with metals were characterized with respect to metal loading (EPMA), structure (XRD), texture (BET), morphology (SEM), Rh dispersion (oxygen chemisorption), surface acidity (pyridine adsorption) and chemical nature of introduced copper and iron species (UV-vis-DRS). The rhodium-containing SBA-15 samples were found to be active catalysts for the N2O decomposition reaction. Deposition of Al on the Rh-loaded catalyst increased its activity. An opposite effect was observed for the samples modified with Cu and Fe

Thermal transformation of polyacrylonitrile deposited on SBA-15 type silica : effect on adsorption capacity of methyl-ethyl ketone vapor

Thermogravimetry, diffuse reflectance infrared Fourier transform spectroscopy, and X-ray photoelectron spectroscopy (XPS) were used for the studying of ther- mally induced structural changes of polyacrylonitrile (PAN) deposited on the surface of SBA-15 type meso- porous silica. Polymer was introduced onto the support by the precipitation polymerization of acrylonitrile in aqueous suspension of SBA-15. Low temperature transformation (to 723 K) of the deposited PAN was analyzed. It was found that at about 523 K, exothermic cyclization of polymer chains to the so-called ladder form of PAN occurred. However, the total cyclization of PAN required higher carbonization temperatures, at which gradual dehydroge- nation followed by graphitization was initiated. XPS revealed that the cyclic form of PAN and a relatively large amount of carbonyl species, formed during the carboniza- tion of the PAN/SBA-15 composite at 623 K, were responsible for the high sorption capacity in the methyl– ethyl ketone (MEK) vapor elimination. The efficiency in the MEK adsorption was also influenced by the content of PAN-derived carbon deposited on the SBA-15 surfac

On mechanism of formation of SBA-15/furfuryl alcohol-derived mesoporous carbon replicas and its relationship with catalytic activity in oxidative dehydrogenation of ethylbenzene

A series of CMK-3-like carbon replicas was synthesized by precipitation polycondensation of furfuryl alcohol in an aqueous slurry of SBA-15 at a polymer/SiO2 mass ratio of 0.50–2.00. Changes in textural and structural parameters of SBA-15 after polymer deposition were studied by N2 adsorption and X-ray diffraction. Morphology of the replicas was investigated by transmission electron microscopy, while their surface composition was determined by temperature-programmed desorption and X-ray photoelectron spectroscopy. The mechanism of deposition of poly(furfuryl alcohol) (PFA) onto silica surface was elucidated. It was found that PFA accumulates in SBA-15 pores randomly; certain channels are completely filled, while others remain partially empty. The incomplete filling of mesopores results in “pseudo-CMK-3” structures featuring the bimodal porosity (the typical mesopores of CMK-3 are accompanied by broader ones formed by the coalescence of adjacent partially hollow pores). The total filling of pores with PFA leads to the formation of good-quality CMK-3. The carbon replicas exhibited the presence of abundant amounts of superficial oxygen-containing moieties. These entities are responsible for high activity of the materials in the oxidative dehydrogenation (ODH) of ethylbenzene, bringing evidence supporting the mechanism of active coke, considered as governing the catalytic performance of carbon materials in ODH of alkanes.This work was supported by the Polish National Science Centre under the grant no. DEC-2011/01/N/ST5/05595. The research was carried out with the equipment purchased thanks to the financial support of the European Regional Development Fund in the framework of the Polish Innovation Economy Operational Program (contract No. POIG.02.01.00-12-023/08). The research was carried out using the infrastructure of the AGH Centre of Energy, AGH University of Science and Technology

Investigation on the Low-Temperature Transformations of Poly(furfuryl alcohol) Deposited on MCM-41

MCM-41-type mesoporous silica was used as a support for poly(furfuryl alcohol) deposition. This material was produced by precipitation–polycondensation of furfuryl alcohol (FA) in aqueous slurry of the SiO2 support followed by controlled partial carbonization. By tuning the FA/MCM-41 mass ratio in the reaction mixture, various amounts of polymer particles were introduced on the inner and outer surface of the MCM support. The thermal decomposition of the PFA/MCM-41 composites was studied by thermogravimetry (TG) and spectroscopic techniques (DRIFT, XPS), whereas the evolution of textural parameters with increasing polymer content was investigated using low-temperature adsorption of nitrogen. The mechanism of thermal transformations of PFA deposited on the MCM-41 surface was discussed in detail. It was found that heating at a temperature of about 523 K resulted in opening of the furan rings and the formation of γ-diketone moieties, which were found to be the highest effective surface species for the adsorption of polar volatile organic compounds. A further increase in calcination temperature caused a drop in the amounts of surface carbonyls and the appearance of condensed aromatic domains.This work was supported by the Polish Ministry of Science and Higher Education under Grant N N507 553238. Rafał Janus thanks the Foundation for Polish Science MPD Programme cofinanced by the EU European Regional Development Fund for the financial support. The research was carried out with equipment purchased thanks to financial help from the European Regional Development Fund within the framework of the Polish Innovation Economy Operational Program (Contract POIG.02.01.00-12-023/08)

Oxidative Dehydrogenation of Ethylbenzene Over Poly(furfuryl alcohol)-Derived CMK-1 Carbon Replica

Poly(furfuryl alcohol) was introduced into a pore system of MCM-48 silica by the precipitation polycondensation of furfuryl alcohol (FA). The complete filling of the pores without the deposition of significant amounts of polymer on the external surface of MCM-48 was obtained at the FA/MCM-48 mass ratio close to 1.0. The final structure of carbon replica was formed by subsequent carbonization and extraction of SiO2 with HF. The carbonization temperature strongly influenced the surface composition of the formed carbon replicas. The highest catalytic activity in the oxidative dehydrogenation of ethylbenzene was observed for CMK-1 with the highest concentration of phenol and carbonyl groups, recognized as active sites of the studied reaction.This work was supported by the National Science Centre under the Grant No. 2013/09/B/ST5/03419. The research was carried out with the equipment purchased thanks to the financial support of the European Regional Development Fund in the framework of the Polish Innovation Economy Operational Program (contract No. POIG.02.01.00-12-023/08)