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The Effect of Selected Process Conditions on Microstructure Evolution of the Vacuum Brazed Joints of Hastelloy X Nickel Superalloy Sheets

Krystek Kamil, Krzanowska Karolina, Wierzbińska Małgorzata, Motyka Maciej

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 4

1551--1561

EN

High temperature vacuum brazing is a well-known and commonly used method for joining of nickel based elements and subassemblies of gas turbines, both for stationary and aviation applications. Despite the fact that currently used brazing filler metals meet stringent requirements of aviation and energetic industries, a lot of effort is spent on improving operational properties of the joints through modification of chemical composition or brazing process parameters. This paper aims for both of these aspects - its purpose is evaluation of the impact of filler metal composition, brazing gap width and process conditions on the microstructure of joints between sheet metal elements made of Hastelloy X nickel superalloy. Two different Ni-based filler materials (BNi-2 and Amdry 915) were investigated, based on the results of light and scanning electron microscopy evaluations, energy dispersive X-ray spectroscopy and hardness measurements.

2

The influence of cement bypass dust on the properties of cement curing under normal and autoclave conditions

Tkaczewska Ewelina

Structure and Environment

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2019

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Vol. 11, no. 1

5--22

EN

This paper analyses the properties of cement binders composed with cement CEM I 42.5R and cement bypass dust in amount of 0.5, 1.0 and 5.0% by mass of binder, curing under standard and additionally autoclave conditions. The bypass dust increases the water content for standard consistency and delays the initial setting time of binder. The cement paste containing 5% of dust reveals the change in volume by 6 mm according to Le Chatelier test. After 2 days, the compressive strength of cement mortar containing bypass is comparable to that of Portland cement mortar, but at later time the strength development of this cement binder is slower. The addition of cement bypass dust in amount to 1% can obtain the cement of strength class of 42.5R according to standard PN-EN 197-1. The autoclave curing improves the compressive strength of cement mortar. The SEM/EDS observations confirm the presence of low crystalline C-S-H gel and well-formed tobermorite fibres in autoclaved cement mortar containing 5% of cement bypass dust.

PL

W pracy analizowano właściwości spoiw cementowych zawierających w składzie cement portlandzki CEM I 42,5R i pył z instalacji bypassa pieca cementowego w ilości 0,5, 1,0 i 5,0% masy spoiwa, dojrzewających w warunkach normalnych i dodatkowo w autoklawie. Pył z bypassa zwiększa ilość wody niezbędnej do uzyskania konsystencji normowej oraz opóźnia początek czasu wiązania spoiwa. Zaczyn zawierający 5% pyłu wykazuje zmianę objętości o 6 mm według Le Chateliera. Po dwóch dniach wytrzymałość na ściskanie zaprawy ze spoiwa zawierającego pył z bypassa jest porównywalna z wytrzymałością zaprawy z cementu portlandzkiego, ale w miarę upływu czasu przyrost wytrzymałości zaprawy z tego spoiwa jest mniejszy. Dodatek pyłu z bypassa w ilości nieprzekraczającej 1% pozwala otrzymać cement klasy wytrzymałości 42,5R według wymagań normy PN-EN 197-1. Autoklawizacja zwiększa wytrzymałość na ściskanie zaprawy cementowej, a pył z bypassa stanowi jeden z czynników poprawiających właściwości wytrzymałościowe. Obserwacje SEM/EDS potwierdzają obecność słabo wykrystalizowanego żelu C-S-H i dobrze wykształconych włókien tobermorytu w próbce zaprawy zawierającej 5% pył z bypassa dojrzewającej w warunkach autoklawu.

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Badania wybranych właściwości skór modyfikowanych minerałami naturalnymi z dodatkiem preparatu na bazie poliheksametylenobiguanidy

Ławińska K., Gandaszewska D., Kozar O., Sprynskyy M., Wionczyk B.

Technologia i Jakość Wyrobów

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2017

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R. 62

86--95

PL

Zbadano strukturę i wybrane parametry fizyko-mechaniczne, higieniczne i mikrobiologiczne podszewkowych skór obuwiowych z wypełnieniem opartym na naturalnych kompozytach mineralnych: zeolicie (MMZ), montmorylonicie (MMT) z dodatkiem preparatu na bazie poliheksametylenobiguanidy (PHMB). Badania wykazały poprawę badanych właściwości modyfikowanych próbek w odniesieniu do skór bez dodatku PHMB.

EN

The structure and the selected physical and mechanical, hygienic and microbiological parameters of footwear lining leather with filling based on natural mineral composite materials: zeolite (MMZ), montmorillonite (MMT) with an addition of a preparation based on polyhexamethylene biguanide (PHMB) were tested. The research has shown an improvement in the tested properties of the modified samples in relation to leather without PHMB.

4

The structure and corrosive properties of the CoCr-base dental alloy obtained by soft material milling followed by sinterization

Rylska D., Sokołowski G., Konieczny B., Sokołowski J.

Journal of Achievements in Materials and Manufacturing Engineering

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2016

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Vol. 74, nr 2

60--71

EN

Purpose: Presented researches aimed at evaluating the structure and corrosion properties of CoCr-base elements fabricated by means of soft material milling with later sinterization in a protective atmosphere in comparison to casted alloy. Design/methodology/approach: CoCr-base samples were fabricated by soft material milling followed by sinterization in neutral gas environment and casted by traditional casting techniques. EDS-SEM study was used to evaluate the microstructure and quantitative analysis of chemical composition. Corrosion resistance evaluation was based on examining corrosion parameters (Ecorr, jcorr, Rpol), corrosion behaviour of both kind of samples was also studied by using open circuit potential v/s time measurements to assess the protective nature of the applied manufacturing methods and by potentiodynamic polarisation technique. Findings: Differences in structure were found, sintered material was more homogenous in comparison to dendritic structure of the cast alloy. Corrosion parameters (corrosion potential - Ecorr, corrosion current density - jcorr, polarization resistance Rp , open circuit potential versus time - OCP) indicate higher corrosion resistance of sintered element. Course of the polarization curve proves, that the sintered alloy exhibits better self-passivating properties in comparison to casted material. Research limitations/implications: The research was carried out on samples, not on final restoration elements. As the technology based on soft CoCr-base alloy milling followed by sinterization in neutral gas environment has been developed last years, additional investigations are needed to obtain more precise results in corrosion properties evaluation. Originality/value: PM technology based on soft material milling with later sintering in a protective atmosphere is the new technology used for fabrication of metal prosthodontic dentures. This method seems to be promissing alternative to laser micro-sintering, and makes it possible to achieve a product with a far more homogenous structure in comparison to traditional casting and does not require as expensive instrumentation necessary for the SLM method. It is crucial to examine in details the corrosion resistance of elements obtained by this new technology.

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Microstructural and Equilibrium Adsorption Study of the System of Waste Foundry Molding Sand/Cu (II) Ions

Strkalj A., Glavas Z., Slokar L.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 4

1805--1812

EN

This paper deals with the waste foundry molding sand which originally comes from the casting production. Adsorption of Cu (II) ions on the waste foundry molding sand was studied. Experimental data were processed using adsorption isotherms. Obtained results show that the experimental data are best described by the Langmuir isotherm. The following adsorption capacities are obtained: 7.153 mg/g to 293 K, 8.403 mg/g at 333 K and 9.208 mg/g at 343 K. The kinetics and thermodynamics of the process were analysed. The obtained results indicate that the adsorption process takes place according to the pseudo second order kinetic model with the following constants: 0.438 g/mg min at 293 K, 0.550 g/mg min at 333 K and 1.872 g/mg min at 343 K. The following values of ΔG° were obtained: − 95.49 J/mol at 293 K, − 736.99 J/mol at 333 K and − 1183.46 J/mol at 343 K. The value of ΔH° is − 4.16 kJ/mol and the value of ΔS° is 15.17 J/molK. These results were confirmed by microscopic examinations. The results indicate that the adsorption process of Cu (II) ions on waste foundry molding sand is possible. Results of microscopic examinations show the homogeneity of the surface, which is proof of the chemisorption. Cu (II) ions on the surface of the waste foundry molding sand were detected after adsorption by EDS analysis, which proves the existence of the adsorption process.

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SEM/EDS and Raman Micro-Spectroscopy Examination of Titanium-Modified Polypropylene Fibres

Cieślak M., Puchowicz D, Kamińska I.

Fibres & Textiles in Eastern Europe

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2014

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Vol. 22, no. 3 (105)

47--53

EN

In order to impart photo-catalytic properties to fibres, one can modify them by means of titanium dioxide. Such a modification should provide the best effectiveness with no deterioration in the basic properties of the fibres modified. Accordingly the modifiers should be deposited on the surface of fibres instead of adding them to the whole mass of the fibreforming polymer. To characterise polypropylene fibres (PP) modified with titanium dioxide doped with nano silver (TiO2/Ag), Raman micro-spectroscopy and SEM/EDS microanalysis were used. The combination of both techniques in the analysis of the fibre surface and cross-section allows qualitative and structural assessment of the distribution of titania modifier in the fibre.

PL

Do nadawania włóknom funkcji fotokatalitycznych stosuje się modyfikacje ditlenkiem tytanu. Modyfikacja taka powinna zapewnić najlepszą efektywność fotokatalityczną bez pogorszenia podstawowych właściwości modyfikowanych włókien. W związku z tym modyfikator powinien znajdować się na powierzchni włókien, a nie w całej objętości polimeru włóknotwórczego. Do oceny efektu modyfikacji włókien polipropylenowych (PP) ditlenkiem tytanu domieszkowanym srebrem (TiO2/Ag) zastosowano techniki mikro-spektroskopii Ramana oraz elektronowej mikroskopii skaningowej połączonej z mikroanalizą rentgenowską SEM/EDS. Połączenie obu technik do analizy powierzchni oraz przekroju poprzecznego włókien (PP) pozwoliło na ocenę jakościowego i strukturalnego efektu modyfikacji.