In this paper, we present indirect methods to define the change in the rates of hydrolysis and condensation reactions of a silica oxide network formed of (3-glycidoxypropyl)methyltriethoxysilane (GPTMS) and (3-aminopropyl)triethoxysilane (ApTEOS), which was strongly dependent upon the nature of the solvent used in the reaction environment, such as methanol, ethanol, propanol, butanol and acetone. Electron microscopy (SEM), focused ion beam scanning electron microscopy (FIB), and Raman spectroscopy were used to investigate the morphology and structure changes. UV-VIS spectrometry, a wettability test, a scratch test and electrochemical tests, namely - Tafel's polarization and electrochemical impedance spectroscopy (EIS), were used to analyze the functional changes in the obtained silica coatings. The coating synthesized in a methanol environment showed a polarization resistance (Rp) almost an order of magnitude greater than those synthesized in the other organic solvents. The greatest thickness, nearly 1.5 μm, was obtained with the ethanol-based coatings. Almost twice as much force (near 11 N) was required to detach the acetone-based coatings, compared to the other coatings. Propanol and butanol contribute to the defects created and the decreased protection properties in the final materials and show a statistically significant influence on the formed corrosion film under sol-gel coatings, particularly for coatings based on propanol. No statistically significant influence of the solvents was observed on the thickness of coatings prepared with butanol or acetone.

This paper presents the result of the investigation of organically modified silica (ORMOSIL)-zirconia coatings used to enhance their protective properties, namely corrosion and scratch resistance. Two different materials, i.e., SiO2/ZrO2 and SiO2/GPTMS/ZrO2, were synthesized, measured, and analyzed to find the difference in the used organosilane precursor (dimethyldiethoxysilane and (3-glycidoxypropyl)trimethoxysilane, respectively). SiO2/ZrO2 coatings showed higher hardness than SiO2/GPTMS/ZrO2. Moreover, the value of polarization resistance (Rp) for SiO2/GPTMS/ZrO2 coated 316L steel relative to the uncoated one was obtained. It was nearly 84 times higher. The coating delamination was observed with load 16N. Additionally, the corrosion mitigation for 316L coated by SiO2/GPTMS/ZrO2 was observed even after extended exposure to corrosion agents.

The detailed information about the growth of organically modified silica networks regarded as useful for barrier coatings and membrane coatings preparation are the subject of this paper. The networks obtained using different precursors containing non-hydrolysable organic groups: dimethyldiethoxysilane – dMdEOS, ethyltriethoxysilane – EtEOS, n-propyltriethoxysilane – nPtEOS have been investigated with rheology and Raman spectroscopy of solutions. The polycondensation degree during aging has been calculated. Individual networks have been monitored for selected points during 654 h of aging. Thanks to the completion of rheology and Raman spectroscopy investigations different influence of aging and physicochemical interaction occurring in particular sols and influencing their rheological behavior have been revealed. The observed differences also apply to the type of structures created by hydrolysis and condensation reaction and are connected with organic group functionalizing silica network.

W ostatnich dwóch dekadach obserwuje się intensywny rozwój narzędzi do anali-zy powierzchni przełomu i charakteryzacji jego topografii w ujęciu ilościowym. Na tym tle interesującym narzędziem, dobrze zdefiniowanym matematycznie i rozwijanym in-tensywnie w wielu ośrodkach, jest geometria fraktalna, której zastosowanie w mechani-ce pękania materiałów jest coraz powszechniejsze-szczególnie dla I sposobu pękania. Jednak niewiele miejsca poświęca się badaniom powierzchni przełomu z wykorzysta-niem geometrii fraktalnej dla mieszanych sposobów rozwoju pękania zmęczeniowego. Dlatego też w pracy autorzy zaprezentowali wyniki badań stali P355NL1 i S355J0 pod-danej I i II sposobowi obciążania szczeliny w trakcie badań zmęczeniowych. Szczegóły badań i analiz numerycznych przedstawiono w pracach [1, 2]. Dla otrzymanych przełomów wyznaczano następnie pojemnościowy wymiar frak-talny (box-counting), który jako jeden z niewielu daje się łatwo zastosować w metodach numerycznych. Wymiar fraktalny określono dla profilu uzyskanego przez przecięcie powierzchni przełomu prostopadle do średniej płaszczyzny przełomu. Stąd obliczono wymiar samej powierzchni przełomu, który w oparciu o twierdzenia matematyczne, jest o jeden większy od wymiaru jej profilu. Najpierw jednak zarejestrowano obraz profilu w postaci pliku graficznego, poprzez mikroskop sprzężony z kamerą, a następnie pod-dano go obróbce numerycznej. Należy zwrócić uwagę, że wymiar fraktalny istotnie za-leży od powiększenia, przy którym jest rejestrowany obraz profilu. Wartość wymiaru rośnie bowiem asymptotycznie wraz z powiększeniem aż do osiągnięcia wartości cha-rakterystycznej (rys. 1). Dla analizowanych profili ten charakterystyczny wymiar frak-talny uzyskiwano już przy powiększeniach rzędu 600x. Celem obróbki numerycznej było natomiast uzyskanie linii konturu zarejestrowanego profilu, dla którego ostatecznie obliczano wymiar fraktalny. W pierwszej kolejności należało obraz poddać binaryzacji. Polega ona na zamianie wszystkich odcieni ciemniejszych, niż zadany poziom szarości n na kolor czarny a odcieni jaśniejszych na kolor biały. Istotny jest tu wybór progu n, przy którym dokonywana jest binaryzacja. Z doświadczenia wiadomo, że operację tą należy przeprowadzać dla poziomu szarości odpowiadającego ekstremalnym wartościom wymiaru fraktalnego.

In this study, a complete method of determination of the fractal dimension for fracture surfaces of ferrous alloys has been proposed. This dimension is determined for the vertical profile obtained by the profile technique cross-section. The image of the profile, seen through the microscope coupled with a camera, is recorded in a computer, where numerical processing is performed. For calculation of the same fractal dimension, the fd3 program has been used, which is available through the Internet. The essential element of the method is optimisation concerning microscopic magnification (scale of a length), resolution of the recorded image and selection of the grey level threshold at binarization. The tests for the stability of discretization, which enable minimization of the error of the measurement, have also been carried out. These tests consist in checking the difference in fractal dimensions for the same profile obtained in two different methods of contouring as well as the difference between capacitive, informative and correlative dimensions. In both cases, too big difference suggests that the determined dimension is not reliable. This method allows determination of the fractal dimension with an absolute accuracy of 0.05 in non-dimensional units. The method has been employed in many studies. In this paper the following tests have been presented: a “fractal map” of the fracture surface was made, an influence of the mechanical notch radius in a compact specimen on the fractal dimension of the fracture surface, an influence of the distortion rate on the fractal dimension, an effect of fatigue crack propagation rate on the fractal dimension and influence of the stress-intensity factor on the fractal dimension of the fracture surface. The following materials were examined: Armco iron, P355N steel and 41Cr4 steel in different states after the heat treatment. The measurements have been made for the specimens of the compact type. There was considered an influence of location of the place of measurement on the fractal dimension being determined. The dimension was determined on the profiles lying longwise and crosswise the crack propagation direction. It has been found that the fractal dimension of the fracture surface does not depend on a place of measurement. This suggests, among other things, that a distinction between the places, which were created under conditions of the plane stress, and the places, which were created under conditions of the plane strain state, cannot be made with the help of the fractal dimension. When testing an influence of the radius of the mechanical tip notch on the fractal dimension of a fracture surface, this dimension was determined in the places located at different distances from the tip of the mechanical notch. With respect to the radii up to 1.0mm, no significant differences in fractal dimensions have been found. The fractal dimensions of the fracture surface for all examined materials were practically the same and they ranged from 2.02 to 2.10. However in some ranges of da/dN rate the dimension was changing inversely proportional to da/dN. Obtained results confirm that fractal dimension do not depend on the investigated material.