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1

Study of the impact of adhesion promoters on the properties of road bitumens

Pyrig Yan, Kishchynskyi Serhii, Galkin Andrii, Oksak Serhii, Poliak Olha, Sidun Iurii, Gunka Volodymyr

Budownictwo i Architektura

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2025

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Vol. 24, no. 4

art. no. 25007

EN

The influence of cationic adhesion promoters of the amine type on the properties of petroleum road bitumens is studied in the article. The impact of the selected adhesion promoters on standard quality indicators of bitumen, such as penetration, softening point, and penetration index, is evaluated. The effect of the promoters on bitumen adhesion is assessed using the bottle rolling method and the glass surface adhesion method. The thermal stability of the promoters was determined by evaluating the reduction in bitumen adhesion after short-term ageing. The influence of adhesion promoters on the bitumen contact angle is also investigated. The following set of indicators is proposed for the evaluation of the effectiveness and thermal stability of adhesion promoters.

2

Comprehensive temperature performance evaluation of asphalt mastics containing hydrated lime filler based on dynamic shear rheometer testing

Ryś Dawid, Jaskuła Piotr, Szydłowski Cezary

Roads and Bridges - Drogi i Mosty

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2024

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Vol. 23, no. 4

355--373

EN

The paper focuses on exploring the potential for effective testing of asphalt mastics in the full range of temperatures using the Dynamic Shear Rheometer (DSR) apparatus. Six various types of asphalt mastics were selected to enable the evaluation of the effects of hydrated lime and bitumen modification, both before and after aging. Different DSR tests covered the whole range of service temperatures from –20°C to 64°C. Multiple Stress Creep Recovery test indicated that in the case of mastics with mixed filler (containing hydrated lime) the non-recoverable compliance at the stress level of 3.2 kPa was lower by half indicating much higher resistance to permanent deformations. Linear Amplitude Sweep Test showed that fatigue life calculated at 2.5% strain is almost 3 times greater when adhesive agent or hydrated lime is applied. Low-temperature rheological properties of mastics were investigated based on relaxation tests and it was concluded that mastics with hydrated lime have slightly lower stress relaxation capacity than the remaining mastics with lime filler.

PL

W artykule przeanalizowano możliwości skutecznego badania właściwości mastyksów asfaltowych w pełnym zakresie wartości temperatury z zastosowaniem reometru dynamicznego ścinania (DSR). Badania przeprowadzono na sześciu różnych mastyksach asfaltowych, aby umożliwić ocenę wpływu wapna hydratyzowanego oraz modyfikacji asfaltu na właściwości mastyksu, zarówno przed starzeniem, jak i po nim. Różne badania przeprowadzone w reometrze dynamicznego ścinania dały obraz właściwości mastyksów w całym zakresie eksploatacyjnych wartości temperatury: od –20°C do 64°C. Test pełzania i nawrotu MSCR wykazał na poziomie obciążenia 3,2 kPa dwukrotnie niższą wartość nieodwracalnej podatności na pełzanie w przypadku mastyksów z wypełniaczem mieszanym (zawierającym mączkę wapienną i wapno hydratyzowane), co wskazuje na ich znacznie wyższą odporność na deformacje trwałe. Test liniowego zwiększania amplitudy LAS wykazał, że trwałość zmęczeniowa obliczona dla odkształcenia 2,5% jest niemal trzykrotnie wyższa dla mastyksów zawierających środek adhezyjny lub wapno hydratyzowane. Właściwości reologiczne mastyksów w niskich wartościach temperatury analizowano na podstawie badań relaksacji. Stwierdzono, że mastyksy z wapnem hydratyzowanym mają nieco niższą zdolność relaksacji naprężeń niż pozostałe mastyksy, zawierające wyłącznie mączkę wapienną.

3

Wpływ rodzaju wosków na wybrane właściwości biokompozytów

Dobrosielska Marta, Dobrucka Renata, Kurzydłowski Krzysztof J., Przekop Robert E.

Przemysł Chemiczny

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2024

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T. 103, nr 7

780--785

PL

W celu zbadania wpływu symulowanych niekorzystnych warunków atmosferycznych na właściwości mechaniczne i powierzchniowe kompozytów na osnowie polilaktydowej, wytworzono metodą wtrysku bezpośredniego kilka materiałów zawierających jako napełniacz amorficzną ziemię okrzemkową oraz różne rodzaje wosków, które zastosowano w celu poprawy właściwości reologicznych. Wytworzone kompozyty cechowały się zawartością ziemi okrzemkowej w zakresie 2,5-15% mas. oraz wosku pszczelego (zawartość 0,5% lub 1% mas.) lub wosku syntetycznego (zawartość 0,5% mas.). Na podstawie przeprowadzonych badań stwierdzono, że dodatek ziemi okrzemkowej w połączniu z dodatkiem wosków korzystnie wpływa m.in. na hydrofobowo-hydrofilowy charakter powierzchni kompozytów, gdzie po 20 dniach kondycjonowania próbek w komorze klimatycznej dla największych stężeń ziemi okrzemkowej odnotowano wzrost kąta zwilżania do maksymalnie 27,4° w porównaniu z czystym polilaktydem.

EN

Polylactide (PLA) was modified by addn. of amorphous diatomaceous earth, synthetic wax and beewax (2.5-15% by mass, 0.5% by mass and 0.5% or 1% by mass, resp.) and direct injection molding to improve its rheol. properties and then studied for tensile strength, elongation at break, flexural stress and flexural modulus as well as for wetting angle optionally after conditioning the samples in a climate chamber for 20 days. The modification resulted in increasing of PLA elasticity as well as in changing hydrophobic-hydrophilic character of the PLA surface and in an increase of the wetting angle up to 27.4° when compared to the pure PLA.

4

Reasons for lack of adhesion of polyurea coatings to concrete substrates in chemically aggressive water tanks

Banera Janusz, Maj Marek

Materiały Budowlane

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2024

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nr 12

20--26

EN

The article discusses the use of polyurea coatings to strengthen waterproofing in liquid tanks, the difficulties associated with the application of coatings and maintaining their durability during long-term use. The causes of detachment of coatings from the substrate, their too rapid aging, problems related to the preparation of the concrete substrate, the efficiency of technical equipment and the application technique itself, as well as the influence of many other factors on the technical degradation of polyurea coatings are presented.

PL

W artykule poruszono zagadnienia zastosowania powłok polimocznikowych do wzmacniania izolacji przeciwwodnej w zbiornikach na ciecze, trudności związane z aplikacją powłok oraz z utrzymaniem ich trwałości podczas długoletniego użytkowania. Przedstawiono przyczyny odspojeń powłok od podłoża, ich zbyt szybkiego starzenia, problemy związane z przygotowaniem podłoża betonowego oraz sprawność sprzętu technicznego i techniki aplikacji, a także wpływ wielu innych czynników na degradację techniczną powłok polimocznikowych.

5

The Microstructural Evolution of the Welded Joint of Super 304H Stainless Steel after 1000 Hours of Ageing at 700 and 750°C

Puszczało Tomasz, Purzyńska Hanna, Sroka Marek, Sówka Karol, Zieliński Adam

Archives of Metallurgy and Materials

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2024

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Vol. 69, iss. 3

1241--1244

EN

This study presents the results of microstructure and hardness tests of a homogenous welded joint made of Super 304H stainless steel after 1000 h of ageing at the temperature of 700 and 750°C. Super 304H steel is commonly used for high-pressure elements of modern power units for supercritical steam parameters. The article compares hardness with the microstructure images in the initial state and after ageing. The microstructure tests were carried out based on scanning microscopy, while the hardness tests were carried out on a stationary hardness tester in the HV10 scale. An increase in hardness after ageing was observed, which is directly related to the initiated precipitation process, both in the weld and base materials.

6

Safety analysis of complex multistate ageing system

Kołowrocki Krzysztof

Safety and Reliability of Systems and Processes

|

2023

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Summer Safety and Reliability Seminar 2023

79--98

EN

Recent developments of an innovative own earlier approach to safety analysis of a complex multistate ageing system impacted by its operation processes are presented. A safety function and other safety indicators are defined for a complex multistate ageing system changing its functional structure and consequently its safety structure and its components safety parameters during the operation and determined under the assumption that its components have piecewise exponential safety functions. Results are applied to examine safety of port and maritime transportation systems.

7

Investigating the ageing process of polymer modified bitumen using a modified Thin-Film Oven Test in the aspect of recycling purpose

Farid Miftah, Król Jan

Roads and Bridges - Drogi i Mosty

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2023

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Vol. 22, no. 4

379--386

EN

Polymer Modified Bitumen (PMB) is a widely used material for road construction. Commonly, PMBs are produced by mixing bitumen with various types of Styrene- Butadiene–Styrene (SBS) copolymers and, if necessary, with another additive such as a cross-linking agent to improve the material’s performance. The ageing process of PMBs is more complex than unmodified bitumen due to molecular interactions between the bitumen and the polymer. Previous studies suggest that the polymer modifier dominates the chemical degradation of PMBs during short-term ageing, while long-term ageing is dominated by bitumen oxidation. As a result, RAP containing PMB as its binder still contains polymer in its chemical composition, emphasizing the need for a comprehensive understanding of the ageing process of PMBs. In current practice, RAP is heated before being mixed with virgin materials to allow reactivation of its aged binder. This study proposes a modified Thin-Film Oven Test (TFOT) as an ageing simulation method, with variations in time and temperature to simulate ageing during the RAP mixing process. The bitumen oxidation phenomenon mostly dominates the ageing process. From quantitative indices analysis, under short duration and lower temperature conditions, the polymer degradation helps to resist ageing shortly. Moreover, the DSR test shows that ageing caused the PMB to increase in complex modulus while decreasing in phase angle, indicating hardening and shifting toward more elastic behaviour. The most prominent effect of ageing can be observed at lower test temperature for phase angle and higher test temperature for complex modulus. Generally, the ageing conditions’ temperature has a more significant role in dictating the ageing effect on PMB than the duration.

PL

Asfalt modyfikowany polimerami (PMB) to szeroko stosowany materiał do budowy dróg. Powszechnie asfalt modyfikowany polimerami wytwarzany jest poprzez mieszanie bitumu z różnymi rodzajami kopolimerów styrenowo-butadienowo-styrenowych (SBS) oraz, w razie potrzeby, z innym dodatkiem, takim jak środek sieciujący, w celu poprawy wydajności materiału. Proces starzenia asfaltów modyfikowanych polimerami jest bardziej złożony niż niemodyfikowanego asfaltu ze względu na interakcje molekularne między asfaltem a polimerem. Wcześniejsze badania sugerują, że modyfikator polimeru dominuje w degradacji chemicznej asfaltów modyfikowanych polimerami podczas starzenia krótkoterminowego, podczas gdy starzenie długoterminowe jest zdominowane przez utlenianie bitumu. W rezultacie destrukt asfaltowy zawierający asfalt modyfikowany polimerami jako spoiwo nadal zawiera polimer w swoim składzie chemicznym, co podkreśla potrzebę kompleksowego zrozumienia procesu starzenia asfaltów modyfikowanych polimerami. W obecnej praktyce destrukt asfaltowy jest podgrzewany przed zmieszaniem z materiałami pierwotnymi, aby umożliwić reaktywację jego starzejącego się spoiwa. W niniejszym badaniu zaproponowano metodę cienkiej warstwy (TFOT) jako metodę symulacji starzenia, ze zmianami czasu i temperatury w celu symulacji starzenia podczas procesu mieszania destruktu asfaltowego. Zjawisko utleniania bitumu przeważnie dominuje w procesie starzenia. Z analizy wskaźników ilościowych wynika, że w warunkach krótkiego czasu trwania i niższej temperatury degradacja polimeru pomaga w krótkim czasie ograniczyć proces starzenia. Co więcej, badanie DSR wykazało, że starzenie spowodowało wzrost złożonego modułu asfaltu modyfikowanego polimerami przy jednoczesnym zmniejszeniu kąta fazowego, co wskazuje na utwardzenie i przesunięcie w kierunku bardziej elastycznego zachowania. Najbardziej widoczny efekt starzenia można zaobserwować w niższej temperaturze testowej dla kąta fazowego i wyższej temperaturze testowej dla modułu zespolonego. Ogólnie rzecz biorąc, temperatura warunków starzenia odgrywa bardziej znaczącą rolę w dyktowaniu wpływu starzenia na asfalt modyfikowany polimerami niż czas jego trwania.

8

Effect of the structure and hydrothermal conditions on the strength of polymer-ceramic composites

Walczak Agata, Niewczas A. M., Pieniak D., Rogula-Kozłowska Wioletta, Kordos P., Przystupa Krzysztof, Popovych V.

Journal of Achievements in Materials and Manufacturing Engineering

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2023

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Vol. 121, nr 2

327--340

EN

The properties of polymer composites depend on their structures. Good initial properties are often not enough because they change under environmental conditions. Thus, studies of functional properties should provide information about their initial properties and behaviour under operating conditions. The study aimed to determine the effect of the structure of dental composites and the environmental hydrothermal conditions on their mechanical strength. Design/methodology/approach Light-cured polymer matrix ceramic composites (LC PMCCs) were investigated. Commercially available composites and experimental materials with different filler particle contents were tested. Compressive strength, three-point and biaxial flexural strength tests were carried out. The tests were performed using composites without a load history, exposed to a moist environment and hydrothermal ageing. Findings In most cases, changes in compressive strength under the effect of the moist environment and hydrothermal ageing were non-significant. Compressive and three-point flexural strength values obtained for universal-type materials were higher than those obtained for flow-type composites. In contrast, higher values of biaxial flexural strength characterised the latter. Hydrothermal ageing caused the greatest decrease (approx. 60%) in the three-point flexural strength of universal-type composites. The strength degradation of flow-type materials was about 40%. Research limitations/implications It is unknown whether the effects of fatigue due to mechanical and hydro-thermal loads are additive, i.e., whether the principle of superposition applies in the case of combined action of these loads or whether a synergy phenomenon occurs. In the next stages, experiments can be carried out involving the simultaneous operation of both types of force. Practical implications The issue of durability is well established in the field of machine operation and, to a lesser extent, in relation to medical devices. Understanding the importance of the durability of medical facilities is not common. This interdisciplinary project may contribute to the dissemination of knowledge in this field. Originality/value Based on the obtained test results, it should be concluded that the based on the change in the elastic modulus.

9

Effect of Natural Ageing on the Safety Parameters and Performance of TNT-based Melt Cast RDX/TNT Compositions

Sharma Tirupati Chander, Singh Arjun, Soni Pramod Kumar, Singh Vasundhara, Kishore Prateek

Central European Journal of Energetic Materials

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2023

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Vol. 20, no. 2

138--158

EN

2,4,6-Trinitrotoluene (TNT) based melt cast RDX/TNT compositions stockpiled for a period of time were exposed under natural environmental conditions, with humidity and temperature for storage in the range of 40-95% RH and 4-47 °C, respectively. The composition, chemical, thermal and mechanical properties of the RDX/TNT compositions before and after ageing were studied by high performance liquid chromatography, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry and a universal test machine, respectively. In addition, the safety, mechanical sensitivities, detonation velocity and blast parameters were also investigated through vacuum stability tests (VST), a BAM fall hammer apparatus, a BAM friction tester and a piezoelectric accelerator, respectively. The results showed that after ageing, the colour of the composition had become dark but there was no variation in the RDX and TNT content by high performance liquid chromatography (HPLC). The VST results showed that the volume of evolved gas was almost the same and less than 2 mL/g, indicating chemical stability. The results obtained from different analytical techniques demonstrated that there was no significant variation in the chemical, thermal and mechanical properties for the aged samples as compared to the fresh composition. The change in mechanical sensitivity is related to the components and the ageing mode. The detonation velocity and detonation pressure were found to be similar to those of the freshly prepared composition and consistent with the data obtained from overall natural ageing. The results of blast studies revealed that there was either a similar or slight variation in the blast peak over pressure and impulse for RDX/TNT compositions at different locations before and after ageing under natural environmental conditions.

10

Mechanical properties of Super 304H steel after long-term ageing at 650 and 700°C

Zieliński Adam, Sroka Marek, Purzyńska Hanna, Novy Frantisek

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 2

art. no. e144612

EN

The paper shows the degradation process of the modern austenitic Super 304H (X10CrNiCuNb18-9-3) steel which was subjected to long-term aging for up to 50,000 h at 650 and 700°C. The investigations include microstructure examination (SEM), identification and analysis of the precipitation process, and mechanical properties tests. The Super 304H steel has a structure characteristic of austenitic steels with visible annealing twins and single primary NbX precipitates. Long-term aging in the steel leads to numerous precipitation processes of M23C6, MX carbides, σ phase, Z phase, and ε-Cu phase. Precipitation processes lead to a decrease in plastic properties and impact energy as well as alloy over aging. Yield strength and tensile strength values after 50,000 h of aging were similar to those as delivered. The yield and tensile strength value strongly depend on the applied aging temperature.

11

Evolution of the microstructure and mechanical properties of Sanicro 25 austenitic stainless steel after long-term ageing

Sroka M., Zieliński A., Golański G., Pawlyta M., Purzyńska H., Novy F.

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 3

art. no. e149, 2023

EN

A newly developed heat-resistant austenitic steel, Sanicro 25 is currently considered the leading candidate material for an advanced ultra-supercritical installation. The test material was subjected to long-term ageing (up to 30,000 h) at 700 and 750 °C, after which investigations into the microstructure, identification of precipitates, and testing of mechanical properties were conducted. Sanicro 25 had an austenitic microstructure with annealed twins and numerous large primary NbX and Z-phase precipitates in the as-received condition. It was found that the long-term ageing of the steel resulted in numerous precipitation processes. For example, M23C6 carbides, Laves, σ and G phases occurred at the grain boundaries. However, Z-phase precipitates, ε_Cu particles, and Laves phase were observed inside the grains. At the same time, compound complexes of precipitates based on the primary Z-phase precipitates were revealed in the microstructure. The ageing process increased the particle size of M23C6 carbides and the σ phase. After longer ageing times, a precipitate-free zone (PFZ) near the grain boundaries was observed. The precipitation processes initially lead to an increase in the strength properties of the steel. However, after 5000 h, an over-ageing effect was observed at 750 °C, which was not observed at 700 °C.

12

Structure of the S304H Steel after 20,000 Hours of Ageing

Wersta Robert, Zieliński Adam, Sroka Marek, Puszczało Tomasz, Sówka Karol

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 2

487--493

EN

The S304H steel is used in the construction of pressure components of boilers with supercritical operating parameters. The paper presents the results of the research on the microstructure after ageing for 20,000 hours at 650 and 700°C. The microstructure examination was performed using scanning and transmission electron microscopy. The precipitates were identifies using transmission electron microscopy. The influence of ageing time on microstructure changes and the precipitation process of the tested steel is described. The presented research results are an element of material characteristics of the new generation of steel, which are used in the design work of pressure devices of steam boilers and in diagnostic work during operation.

13

Structure of 22Cr25NiWCoCu Austenitic Stainless Steel After Ageing

Sroka Marek, Zieliński A., Puszczało T., Sówka K., Hadzima B.

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 1

175--180

EN

The 22Cr25NiWCoCu austenitic stainless steel was developed by AB Sandvik Material Technology in Sweden. Due to its high creep strength and good corrosion resistance, this material is well suited for use in superheaters in advanced coal-fired power boilers as well as in other types of steam boilers using various types of fuel. The examined material was subject to long-term ageing for the time of annealing up to 20 000 h at 700 and 750°C. Precipitation processes and microstructure stability as-received and after ageing were investigated. Examination of the microstructure was conducted using scanning electron microscopy. The identification of secondary phases was carried out by X-ray phase composition. Using the results of the investigations of precipitation processes in the microstructure, both within the grains and at the grain boundaries, their statistical analysis was carried out. To illustrate this impact, the following parameters were used: surface area and equivalent diameter of precipitates. Based on the surface area measurements, the percentage of the phase in the reviewed photo’s total area was calculated.

14

Safety analysis of critical infrastructure impacted by operation and climate-weather changes - theoretical backgrounds

Kołowrocki Krzysztof

Safety and Reliability of Systems and Processes

|

2021

|

Summer Safety and Reliability Seminar 2021

139--180

EN

The methodology and general approach to critical infrastructure safety and resilience analysis is proposed. The principles of multistate approach to critical infrastructure safety analysis are introduced. There are introduced the notions of critical infrastructure basic safety indicators like, the critical infrastructure safety function, the critical infrastructure risk function and the critical infrastructure fragility curve. The critical infrastructure safety and resilience indicators are proposed to be obtained using probabilistic approach to modelling of operation threats and extreme weather hazard impacts on its assets safety. There are proposed safety and resilience indicators, crucial for operators and users of the critical infrastructure, defined as a complex system in its operating environment. The safety of a critical infrastructure free of any outside impacts is discussed and modelled. The safety indicators of this critical infrastructure are defined. The safety of critical infrastructure impacted by its operation process is considered. The critical infrastructure operation process and its parameters are defined and its characteristics are determined. The safety and resilience indicators of the critical infrastructure related to the operation process impact are proposed. The safety of critical infrastructure impacted by the climate-weather change process at its operating area is considered. The climate-weather change process at the critical infrastructure operating area and its parameters are defined and its characteristics are determined. The safety and resilience indicators of the critical infrastructure related to the climate-weather change process at its operating area impact are proposed. The safety of critical infrastructure impacted by its operation process and climate-weather change process at its operating area is considered. The critical infrastructure operation process related to climate-weather change process at its operating area and its parameters are defined and its characteristics are determined. The safety and resilience indicators of the critical infrastructure impacted by the operation process related to climate-weather change process are proposed. Real critical infrastructures and their assets impacted by their operation processes related to climate-weather change process at their operating area are suggested to be examined and their safety and resilience indicators are proposed to be determined by the proposed methods.

15

Ocena jakości estetycznej włóknisto-cementowych prefabrykatów elewacyjnych z betonu

Woyciechowski Piotr, Jackiewicz-Rek Wioletta

Materiały Budowlane

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2021

|

nr 9

32--35

PL

Przedmiotem artykułu jest metodyka oceny estetyki elewacyjnych płyt cementowo-włóknistych. Przedstawiono propozycję kryteriów takiej oceny, a także propozycję metody badawczej, umożliwiającej prognozowanie zachowania estetyki takich płyt w czasie eksploatacji, na podstawie przyspieszonego badania starzeniowego.

EN

The subject of the article is a methodology for assessing the aesthetics of fiber-cement facade flat-sheets. A proposal of criteria for such an evaluation was presented, as well as a proposal of a research method that would enable the prediction of the aesthetic behavior of such elements during exploitation, based on an accelerated aging test.

16

Microstructure of cast MgBi6X0.5 (X = Ca, Mn, Zn) alloys in peak-aged condition

Gryc Adam, Dybowski Bartłomiej, Jarosz Robert, Kiełbus Andrzej

Journal of Metallic Materials

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2021

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Vol. 73, no. 3

23--28

EN

Cast magnesium alloys are characterised by the lowest density among commercially used structural metals. They are applied mainly in the transportation industry and small, lightweight electronic devices. Due to the low operating temperature of the most widely used alloys from the Mg-Al system, alloys containing rare earth elements with the maximum working temperature reaching 300°C have been developed. However, these alloys are extremely expensive due to the low availability of RE elements. The Mg-Bi system is a promising candidate for the new magnesium-based alloys, as it reveals limited solubility of Bi in Mg enabling precipitation hardening and a high melting point of the Mg3Bi2 phase. The paper presents the results of the analysis of MgBi6 and MgBi6X0.5 (X = Ca, Mn, Zn) alloys’ microstructure in the peak-aged condition. The microstructure of the analysed alloys in the as-cast condition consists of α-Mg solid solution dendrites and Mg3Bi2+α-Mg eutectic compound. Solutionising conducted at 525°C for 8 h, followed by water quenching leads to the dissolution of the intermetallic phases in all of the investigated alloys apart of the MgBi6Ca0.5 alloy. In this case, fine intermetallic phases containing Mg, Bi, and Ca have been found after solutionising. The ageing of the alloys at 200°C results in peak hardness after 120-44 h. The heat treatment leads to the formation of fine strengthening phases within the α-Mg solid solution, characterised by a variety of morphologies -needle, platelet- or lathlike and cuboid. The needle- and platelet- or lathlike phases are found in two sizes -large, with length reaching hundreds of nanometres, and smaller, not exceeding 100 nm. Cuboid particles are found with sizes not higher than 100 nm. The addition of Mn and Zn increases precipitate volume fraction after the heat treatment. Additionally, in the case of the MgBi6Zn0.5 alloy, particles forming an angle of 120° were found, which indicates their presence at the prismatic planes of α-Mg HCP crystal lattice.

PL

Odlewnicze stopy magnezu charakteryzują się najniższą gęstością wśród wszystkich komercyjnie stosowanych stopów konstrukcyjnych. Znajdują zastosowanie głównie w przemyśle transportowym oraz małych, lekkich urządzeniach elektronicznych. Z uwagi na niską temperaturę eksploatacji najpowszechniej stosowanych stopów z układu Mg-Al, opracowano stopy, zawierające pierwiastki ziem rzadkich, znajdujące zastosowanie w temperaturach do 300°C. Jednak stopy z tej grupy są niezwykle drogie, z uwagi na ograniczoną dostępność pierwiastków ziem rzadkich. Obiecującą alternatywę stanowią stopy z układu Mg-Bi, który z uwagi na ograniczoną rozpuszczalność bizmutu w magnezie oraz wysoką temperaturę topnienia fazy Mg3Bi2 umożliwia ich umocnienie na drodze utwardzania wydzieleniowego. W artykule przedstawiono wyniki badań mikrostruktury stopów MgBi6 oraz MgBi6X (X = Ca, Mn, Zn) po starzeniu. Mikrostruktura badanych stopów w stanie lanym składa się z dendrytów roztworu stałego α-Mg oraz mieszaniny eutektycznej Mg3Bi2+α-Mg. Przesycanie, przeprowadzone w temperaturze 525°C przez 8 h z chłodzeniem w wodzie doprowadziło do rozpuszczenia faz międzymetalicznych we wszystkich badanych stopach, z wyjątkiem stopu MgBi6Ca0,5. W jego przypadku po przesycaniu zidentyfikowano w strukturze drobne fazy międzymetaliczne, zawierające Mg, Bi i Ca. Maksymalną twardość stopów po starzeniu w temperaturze 200°C osiągnięto po 120÷144 h. Zastosowana obróbka cieplna doprowadziła do utworzenia się wewnątrz ziaren roztworu stałego α-Mg drobnych faz umacniających o zróżnicowanej morfologii -od iglastej, przez płytkową, po prostopadłościenną. Zaobserwowano dwa typy wydzieleń iglastych i płytkowych -większe, o długości rzędu kilkuset nanometrów oraz mniejsze, nieprzekraczające 100 nm długości. Wydzielenia prostopadłościenne charakteryzowały się rozmiarami, nieprzekraczającymi 100 nm. Dodatek Mn oraz Zn spowodował wzrost udziału objętościowego wydzieleń po obróbce cieplnej. Dodatkowo, w przypadku stopu MgBi6Zn1,5, wydzielenia tworzyły kąt 120°C, co wskazuje na ich obecność na płaszczyznach pryzmatycznych komórki elementarnej α-Mg.

17

Mechanical properties of P91 and PB2 steel after long-term ageing at 620°C

Golański Grzegorz

Journal of Metallic Materials

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2021

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Vol. 73, no. 3

2--6

EN

The article presents the results of research on mechanical properties of martensitic steels, X10CrMoVNb9-1 (P91) and X13CrMoCoVNbNB9-2-1 (PB2), as-received and after 50,000 hours of ageing at 620˚C. The scope of the tests of mechanical properties included a Vickers hardness test, Charpy impact test, and static tensile test. As received, the investigated steels were characterised by relatively high mechanical properties. The long-term effect of temperature and time contributed to a relatively slight decrease in the strength properties and hardness of the tested steels. However, a considerable decrease in the ductility of these alloys was observed. The decrease in mechanical properties after long-term ageing was smaller in the case of the PB2 steel, which was attributed to the beneficial effect of microalloying boron.

PL

W artykule przedstawiono wyniki badań właściwości mechanicznych stali martenzytycznych X10CrMoVNb9-1 (P91) i X13CrMoCoVNbNB9-2-1 (PB2) w stanie dostawy oraz po 50 000 godzinach starzenia w temperaturze 620˚C. Zakres badań właściwości mechanicznych obejmował pomiar twardości metodą Vickersa, próbę udarności oraz statyczną próbę rozciągania. W stanie dostawy badane stale charakteryzowały się względnie wysokimi właściwościami mechanicznymi. Długotrwałe oddziaływanie temperatury i czasu przyczyniło się do względnie niewielkiego spadku właściwości wytrzymałościowych i twardości badanych stali. Obserwowano natomiast znaczące obniżenie ciągliwości tych stopów. Spadek właściwości mechanicznych po długotrwałym starzeniu był mniejszy w przypadku stali PB2, co przypisano korzystnemu działaniu mikrododatku boru.

18

Effect of accelerated ageing on some surface properties of UV-coated hackberry (Celtis australis L.) wood parquet

Ayata Ümit, Esteves Bruno, Gürleyen Levent, Çakicier Nevzat, Ferreira Jose, Domingos Idalina, Türk Mutlu

Drewno : prace naukowe, doniesienia, komunikaty

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2021

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vol. 64, nr 208

17--33

EN

The importance of UV-curable coatings is currently increasing. In the parquet industry, where UV systems are applied, it is beneficial to investigate new tree species as potential raw materials. This study was carried out to determine the effect of accelerated ageing on some surface properties of hackberry (Celtis australis L.) wood treated with UV system parquet varnish. UV system parquet varnishes were applied to hackberry wood surfaces in three and five layers, according to the requirements of industrial applications. The varnished surfaces were then exposed to UV rays for 252 and 504 h using UVA-340 lamps in a QUV ageing device. Glossiness, colour parameters, pendulum hardness and adhesion strength (pull-off) (MPa) were determined for the coated samples before and after ageing, and the results for the aged and unaged test samples were compared. Analysis of variance showed that the results were significant for all tests. The results for all tests varied by ageing time.

19

Novel Composite Solid Propellant with High Resistance to Thermo-oxidative Degradation Reactions, Extended Shelf Life, and Superior Combustion Characteristics

Elbasuney Sherif, Elsaka Eslam, Elbeih Ahmed, Mostafa Hosam E.

Central European Journal of Energetic Materials

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2021

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Vol. 18, no. 1

143--158

EN

Hydroxy-terminated polybutadiene (HTPB) pre-polymer is the main constituent that is responsible for conferring high mechanical properties on composite solid propellants. However, HTPB pre-polymer suffers from oxidative degradation reactions that diminish its mechanical properties and shelf life. Composite solid propellant formulations based on an advanced stabilizing agent (anti-oxidant), Flexzone 6-H, with different curing ratios, 0.7 and 1.1, were developed via mixing and casting under vacuum. The developed formulations were subjected to artificial ageing using Vant Hoff,s formula by isothermal heating at 80 °C for up to 35 days. The change in strain with ageing was evaluated using a uni-axial tensile test. The propellant formulation based on a curing ratio of 0.7 demonstrated a high ageing resistance coefficient and an extended service life of up to 15 years, compared with 5 years for higher curing ratio. A propellant grain is considered to be ‘aged out’ at 30% reduction in its maximum strain value. The propellant formulation based on the 0.7 curing ratio exhibited superior thermal stability as it offered a minimum decrease in heat released after ageing using DSC. Additionally, the 0.7 curing ratio formulations exhibited a minimum change in burning rate and pressure exponent with ageing time. It can be concluded that the propellant with 0.7 curing ratio can maintain its mechanical, thermal, and ballistic properties with ageing.

20

Assessment of the Shelf Life of Composite Solid Propellants in Air and Nitrogen Atmospheres through Thermal Ageing

Keshavarz Mohammad Hossein, Hosseini Seyyed Hesamodin, Mehran Karimi

Central European Journal of Energetic Materials

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2021

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Vol. 18, no. 1

25--45

EN

This work introduces dynamic mechanical thermal analysis (DMTA) as an efficient method for the assessment of the shelf life of solid composite solid propellants in air and nitrogen atmospheres. The samples were aged at three temperatures 323.15, 333.15, and 343.15 K for 60, 120, and 180 days. The two different methods of Arrhenius and Berthelot were used to compare the effects of air and nitrogen atmospheres on the ageing of composite solid propellants. Damping (Tan δ) of composite solid propellants was used to determine the shelf life of the samples based on the loss of half of the physical property Tan δ (50% drop in damping). For the air atmosphere, the calculated activation energy for the degradation reactions of the samples was 86.26 kJ·mol–1. Both models, Arrhenius and Berthelot, confirmed that the shelf lives of the samples under the nitrogen atmosphere are more than four times those in an air atmosphere.