Wyniki wyszukiwania - BazTech

1

Charakterystyka fizykochemiczna musu z marchwi wzbogaconego proszkiem z pestek awokado

Rolewicz Aleksandra, Szmigielski Marek, Grządka Elżbieta

Przemysł Chemiczny

|

2026

|

T. 105, nr 1

60--64

PL

Analizowano zmiany pH, przewodnictwa właściwego oraz zawartości karotenoidów i polifenoli w próbkach musu z marchwi z różną ilością proszku z pestek awokado (MPA). Wraz ze wzrostem ilości MPA obserwowano spadek pH oraz wzrost przewodnictwa, świadczący o obecności kwasowych elektroaktywnych substancji mineralnych. Dodatek MPA zwiększał zawartość związków bioaktywnych (karotenoidów i polifenoli). Szczególnie wyraźny był wzrost zawartości polifenoli, wskazujący na silne właściwości przeciwutleniające MPA. W celu oszacowania wpływu dodatku na zawartość mikro- i makroelementów w musie wykonano analizę zawartości pierwiastków (SEM-EDS). Mikrostrukturę uzyskanych musów oceniono na podstawie analizy mikrografii SEM.

EN

Conductivity, pH, carotenoid, polyphenol and micro- and macronutrient content (SEM-EDS) were detd. in carrot mousse samples contg. various amts. of avocado seed powder (MPA). With increasing MPA content, a decrease in pH and an increase in conductivity were obsd., indicating the presence of acidic electroactive minerals. The addn. of MPA increased the content of bioactive compds. (carotenoids and polyphenols). The increase in polyphenol content was particularly pronounced, indicating the strong antioxidant properties of MPA. SEM imaging revealed an increase in surface roughness and pore vol. in the materials with MPA addition.

2

Gips i jego modyfikacje nanododatkami węglowymi

Fryczkowski Ryszard, Kruczała Robert, Fryczkowska Beata

Polish Journal of Materials and Environmental Engineering

|

2026

|

Vol. 11 (31)

11--24

EN

This review article discusses the potential use of graphene and its derivatives as additives modifying the properties of gypsum products. The paper presents the basic characteristics of gypsum, anhydrite and calcium sulfate hemihydrate, with particular attention paid to hydration and dehydration processes that determine the setting, microstructure and final performance of gypsum binders. The role of conventional admixtures used in gypsum technology is also outlined in order to show the background for the introduction of carbon nanomaterials. The main part of the study analyses the available literature on the influence of graphene, graphene oxide, reduced graphene oxide and graphene nanofibers on gypsum-based composites. The reviewed results indicate that small amounts of graphene materials may increase flexural and compressive strength, reduce total porosity and water absorption, improve water resistance and, in selected systems, enhance thermal conductivity. These effects are attributed mainly to physical and microstructural mechanisms, including nucleation of calcium sulfate dihydrate crystals, pore filling, bridging of microcracks, barrier action against moisture transport and improved compactness of the hardened matrix. At the same time, the efficiency of modification strongly depends on the type of graphene material, its dispersion quality, dosage, water-to-binder ratio and method of composite preparation. Excessive graphene content can lead to agglomeration and deterioration of the reinforcing effect. The review also points to the promising role of graphene in desulfurization gypsum and recycled gypsum systems, which gives this research area both technological and environmental significance.

3

Production of environmentally friendly, sustainable insulation material: Fly ash-based geopolymer

Arioz Evren

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2026

|

Vol. 74, nr 1

art. no. e156768

EN

Geopolymer foams are sustainable, environmentally friendly, and low-cost materials. In this research, fly ash-based geopolymer foams were synthesized using a mixture of sodium hydroxide, sodium silicate, and hydrogen peroxide as the foaming agent. At a constant 80°C curing temperature, curing periods were varied to 4, 15, and 24 hours, while hydrogen peroxide ratios were varied to 0.5%, 1%, 1.5%, and 2%. The effects of peroxide amount and curing duration on thermal conductivity, density, compressive strength, and microstructural properties were examined. The densities and thermal conductivity values decreased with increasing curing duration and hydrogen peroxide ratio. The lowest density was recorded as 1070 kg/m3 for the sample prepared with 2% hydrogen peroxide and cured for 24 hours. Conductivity values varied from 0.247 to 0.108 W/m K. The highest compressive strength value obtained was 9.3 MPa. Quartz and mullite were identified as crystalline phases. The hydrogen peroxide content did not significantly affect the crystalline structures. The weight loss decreased as the hydrogen peroxide ratio increased, according to TGA analysis. BET analysis indicated that the pore size distribution shifted to the smaller pore size region as the peroxide concentration increased. SEM analyses showed a reduction in the presence of unreacted fly ash residues in the samples containing 1.5% and 2% hydrogen peroxide. The geopolymer foams produced in this experimental study meet RILEM requirements for structural and insulating concrete materials with respect to thermal conductivity and compressive strength.

4

Procesy degradacyjne w stalach normalizowanych St37·12 i 18G2A dwóch eksploatowanych konstrukcjach budowlanych z XX wieku

Wichtowski Bernard, Hołowaty Janusz

Welding Technology Review

|

2025

|

R. 97

4--14

PL

Przedstawiono badania strukturalno-wytrzymałościowe stali normalizowanej dwóch konstrukcji budowlanych. Są to blachownicowy most kolejowy wykonany z niemieckiej stali zlewnej eksploatowany od 1938 roku oraz zespół pięciu zbiorników cylindrycznych wykonanych z polskiej stali niskostopowej i użytkowanych od 1973 roku. Wykonano badania chemiczne i mechaniczne oraz metalograficzne w zakresie makro i mikro struktury oraz dodatkowo wyżarzonej normalizacyjnie stali tych obiektów. Są to priorytetowe badania tych gatunków stali budowlanej.

EN

Structural-strength tests of normalized steel of two building structures are presented. There is a plate girder bridge of mild steel in service since 1938 and a complex of five-cylinder tanks with capacity 1500 m3 each, constructed of low-alloy steel, in service since 1937. Chemical and mechanical tests in macro and micro structural range and additionally anneal steels from these structures. There are priority tests for such construction steel grades.

5

Insight into Abrasive Wear of X153CrMoV12 Tool Steel Microalloyed with Varied Niobium Content

Leśniewski Tadeusz, Lachowicz Marzena, Hawryluk Marek, Marzec Jan

Tribologia

|

2025

|

nr 1

17--28

EN

The article analyses the influence of the addition of niobium on the microstructure, hardness, and wear of X153CrMoV12 cold work tool steel. Steels containing 0.06 wt.% and 0.20 wt.% niobium are characterized using light and scanning electron microscopy methods, hardness measurements and tribological tests. To test the abrasion resistance of selected materials, the authors use the T-07 test stand. The behavior of steel under tribological influences is assessed using scanning electron microscopy. The results show that the abrasive particles have an obvious effect on the loss of steel abrasive mass, but the niobium content determines the relative wear resistance. Steel with a niobium content of 0.20 wt.% is characterized by higher hardness, which ultimately results in higher abrasion resistance. This effect is associated with the presence of niobium carbide precipitates in the steel.

PL

Oceniono wpływ dodatku niobu na mikrostrukturę, twardość i zużycie stali narzędziowej do pracy na zimno gatunku X153CrMoV12. Scharakteryzowano stale zawierające odpowiednio 0,06% wag. oraz 0,20% wag. niobu z wykorzystaniem metod mikroskopii świetlnej, elektronowej skaningowej, pomiarów twardości oraz badań tribologicznych. Badanie odporności na ścieranie wybranych materiałów prowadzono na stanowisku badawczym T-07. Zachowanie stali w warunkach oddziaływań tribologicznych oceniono z wykorzystaniem elektronowej mikroskopii skaningowej. Wyniki pokazały, że cząstki ścierne miały oczywisty wpływ na utratę masy ściernej stali, ale zawartość niobu decydowała o względnej odporności na zużycie. Stal o zawartości niobu 0,20% wag. charakteryzowała się wyższą twardością, co przełożyło się ostatecznie na wyższą odporność na ścieranie. Efekt ten powiązano z obecnością w stali wydzieleń węglików niobu.

6

Practical implications of hydrocarbon pollution in the assessment of geotechnical behaviour of cohesive soils

Izdebska-Mucha Dorota, Kiełbasiński Kamil, Doba Paweł, Wójcik Emilia, Žaržojus Gintaras

Technical Transactions

|

2025

|

Vol. 122, iss. 1

art. no. e2025023

EN

The paper presents the results of experimental laboratory investigation of cohesive soils from the Warsaw area, polluted with diesel fuel. The study revealed adverse changes in key physical parameters, sorption capacity and mechanical properties. The results were analysed in relation to pollution degree as well as structural modifications. The obtained findings were further used in numerical analyses to evaluate bearing capacity, foundation settlement, and slope stability, as well as to assess the overall behaviour of contaminated soils serving as building foundations.

7

Wpływ domieszkowania na mikrostrukturę i właściwości dielektryczne K0,5Bi0,5TiO3

Czaja Piotr, Bochenek Dariusz, Jagło Grzegorz, Jędryka Jarosław, Rakus Piotr, Kluczewska-Chmielarz Kamila, Osińska Katarzyna

Przegląd Elektrotechniczny

|

2025

|

R. 101, nr 4

218--221

PL

W artykule przedstawiono technologię oraz wybrane wyniki pomiarów tytanianu bizmutowo potasowego K0,5Bi0,5TiO3 domieszkowanego jonami: Ce4+ i Sr2+ w ilości 0,5% (mol.). Badania mikrostruktury z wykorzystaniem skaningowej mikroskopii elektronowej (SEM) umożliwiły obserwacje poszczególnych etapów technologicznych. Natomiast badania dielektryczne zostały przeprowadzone w szerokim zakresie temperatury od 293 K do 873 K dla częstotliwości od 1 kHz do 2 MHz. Zaobserwowano w obu przypadkach szerokie maksimum wartości stałej dielektrycznej podobne to tego, które obserwowano w próbce bazowej K0,5Bi0,5TiO3.

EN

The article presents the technology and selected measurement results of potassium bismuth titanate K0.5Bi0.5TiO3 doped with ions: Ce4+ and Sr2+ in the amount of 0.5% (mol.). Microstructure studies using scanning electron microscopy (SEM) enabled observation of individual technological stages. Dielectric studies were carried out in a wide temperature range from 293 K to 873 K for frequencies from 1 kHz to 2 MHz. In both cases (for two samples), a broad maximum of the dielectric constant value was observed, similar to that observed in the base sample K0.5Bi0.5TiO3.

8

Effect of cellulose microfibers physical treatment on adhesion in rubber compounds

Dubec Andrej, Labaj Ivan, Dubcová Petra, Vršková Juliána, Bakošová Dana, Bakošová Alžbeta

Polimery

|

2025

|

Vol. 70, nr 11-12

759--765

EN

Effect of physical modification of cellulose microfibers on the adhesion at the interface of rubber compounds was investigated. Cellulose modification was carried out using a pressure process (2 bar) at 121°C in an autoclave or a non-pressure process in a water bath at 100°C. The interactions at the fiber-polymer matrix interface were assessed based on tensile mechanical properties and scanning electron microscopy (SEM) analysis. Cellulose microfibers modified by the autoclave-assisted process exhibited a more developed surface without fiber structural degradation, resulting in a slight increase in tensile strength and a smaller fracture surface compared to the water-bath treated fibers.

PL

Zbadano wpływ fizycznej modyfikacji mikrowłókien celulozowych na adhezję na granicy faz mieszanek gumowych. Modyfikację celulozy prowadzono w procesie ciśnieniowym (2 bar) w temperaturze 121°C w autoklawie lub bezciśnieniowym w kąpieli wodnej w 100°C. Oddziaływania na granicy faz włókno-osnowa polimerowa oceniano na podstawie właściwości mechanicznych przy rozciąganiu oraz za pomocą skaningowej mikroskopii elektronowej (SEM). Modyfikowane w procesie ciśnieniowym mikrowłókna celulozy wykazały bardziej rozwiniętą powierzchnię bez degradacji struktury, co skutkowało nieznacznym wzrost wytrzymałości na rozciąganie i mniejszym udziałem obszaru przełomu w porównaniu z włóknami modyfikowanymi w procesie bezciśnieniowym.

9

Insight into the corrosion in non-ferrous alloy heat exchangers

Lachowicz Marzena M., Lachowicz Maciej B.

Ochrona przed Korozją

|

2025

|

nr 1

2--11

EN

Selected issues relating to the corrosion of non-ferrous heat exchanger components in their operating environment have been presented. With the increasing demand for such equipment, the number of reported corrosion-related failures is steadily increasing, resulting in rising operating costs. This paper introduces the different types of corrosion and defines selected corrosion problems affecting aluminium heat exchanger components. Macroscopic images are shown and the mechanism of corrosion caused by the presence of organic decomposition products on the surface of copper elements is discussed. In relation to copper, an example of corrosion caused by sulphate ions is also presented. The study also includes an example related to the hydrogenation of a titanium heat exchanger plate. The analyses presented in this paper are related to engineering practice and are relevant to the design of thermal energy exchange devices. The possibility of early detection of existing corrosion hazards will also help to prevent potential mechanical failures in heat exchangers.

PL

W pracy przedstawiono wybrane zagadnienia związane z korozją nieżelaznych elementów wymienników ciepła w ich środowisku eksploatacyjnym. Rosnący popyt na te urządzenia powoduje, że ilość odnotowanych awarii wywołanych korozją stale wzrasta, co wiąże się z rosnącymi kosztami ich eksploatacji. W pracy przedstawiono różne typy korozji, a także zdefiniowano wybrane problemy korozyjne dotyczące aluminiowych elementów wymienników ciepła. Pokazano obrazy makroskopowe oraz omówiono mechanizm korozji spowodowanej obecnością produktów rozkładu substancji organicznych na powierzchni elementów miedzianych. W odniesieniu do miedzi przedstawiono również przykład korozji wywołanej jonami siarczanowymi. W ramach badań przedstawiono także przykład związany z nawodorowaniem tytanowej płyty wymiennika ciepła. Przedstawione w pracy analizy związane są z praktyką inżynierską i stanowią istotne znaczenie dla projektowania urządzeń służących do wymiany energii cieplnej. Możliwość wczesnej detekcji istniejących zagrożeń korozyjnych pozwoli również zapobiegać potencjalnym awariom mechanicznym w wymiennikach ciepła.

10

Assessment of the local variability of mechanical parameters of rock material based on the construction of a road tunnel drilled in the Carpathian flysch

Różański Adrian, Bodak Bartłomiej, Masłowski Mikołaj, Pachnicz Michał, Lewandowski Grzegorz

Materiały Budowlane

|

2025

|

nr 9

136--144

EN

The aim of the study was to analyze the local variability of the Carpathian flysch using computer microtomography and nanoindentation. Significant differences in the mechanical and physical properties of the material were demonstrated, confirming the need to assess the microstructure of the rock material for accurate estimation of the prevailing geological conditions. The presented approach to research ultimately improves the safety and efficiency of tunneling work.

PL

Celem badania była analiza lokalnej zmienności fliszu karpackiego za pomocą mikrotomografii komputerowej i nanoindentacji. Wykazano duże różnice we właściwościach mechanicznych i fizycznych badanego materiału, co potwierdza potrzebę oceny mikrostruktury materiału skalnego do prawidłowego oszacowania panujących warunków geologicznych. Przedstawione podejście do badań umożliwia poprawę bezpieczeństwa i efektywności prowadzenia prac podczas drążenia tunelu.

11

Opracowanie składu chemicznego i parametrów obróbki cieplnej cienkościennych odlewów ze staliwa konstrukcyjnego

Garbarz Bogdan, Mazurkiewicz Adam, Spiewok Waldemar, Marczak Marzanna, Gasiński Paweł, Popławski Marcin

Materials Science and Welding Technologies / Technologie Materiałowe i Spawalnicze

|

2025

|

Vol. 69, No. 2

4--8

PL

Na podstawie wyników eksperymentów laboratoryjnych opracowano skład chemiczny staliwa oraz parametry technologii odlewania płyt o grubości ścianki z zakresu 15–20 mm, które w stanie normalizowanym charakteryzują się następującymi właściwościami mechanicznymi: Rm > 550 MPa, Rp0,2 > 400 MPa, A5 > 5 %, przy zachowaniu wartości równoważnika węgla CE < 0,6. Uzyskana granica plastyczności jest istotnie wyższa od najwyższej granicy plastyczności osiąganej dla obecnie stosowanych odlewów normalizowanych ze staliw średniowęglowych niskostopowych, wynoszącej ok. 300 MPa. W odlanych płytach o grubości 15 mm stwierdzono występowanie pustek o maksymalnych rozmiarach liniowych w zakresie 1–2 mm. Średnie wartości porowatości płyt, obliczone na podstawie zmierzonych gęstości, mieszczą się w zakresie od 0,52 % do 1,18 %. Z testów rozciągania próbek wyciętych z badanych staliw wynika, że większy ułamek sumarycznej powierzchni pustek na powierzchni zerwania powoduje uzyskanie mniejszych wartości wydłużenia całkowitego, granicy plastyczności i wytrzymałości na rozciąganie. Wyniki badań wskazują, że jest możliwe zwiększenie właściwości mechanicznych normalizowanego średniowęglowego niskostopowego staliwa powyżej otrzymanych w pracy wartości, przy zachowaniu warunku CE <0,6, w wyniku modyfikacji składu chemicznego w zakresie zawartości C, Mn, Cr oraz V. Dodatkowe polepszenie właściwości można uzyskać w wyniku zmniejszenia wymiarów i ułamka objętości pustek skurczowych.

EN

Based on the results of laboratory experiments, the authors developed chemical composition and casting process parameters for thin-walled steel castings with wall thicknesses restricted within the range of 15 mm to 20 mm. In the normalised state, the aforesaid castings were characterised by Rm > 550 MPa, Rp0.2 > 400 MPa and A5 > 5 %, while maintaining a carbon equivalent (CE) below 0.6. The obtained yield point significantly exceeds that of currently used normalised medium-carbon low-alloy steel castings, typically reaching approximately 300 MPa. In the cast plates with a thickness of 15 mm, it was possible to observe shrinkage cavities, the maximum linear dimensions of which were restricted within the range of 1 mm to 2 mm. The average porosity values, calculated on the basis of measured density, ranged from 0.52 % to 1.18 %. Tensile tests of specimens sampled from the tested castings revealed that a higher fraction of total void area on the rupture surface resulted in lower values of total elongation, yield point and tensile strength. The test results indicate that it is possible to further improve the mechanical properties of nor malised medium-carbon low-alloy cast steel beyond the values obtained within this research work and meet the condition of CE < 0.6 by modifying the chemical composition, particularly in terms of C, Mn, Cr and V contents. Additional improvements in properties could be achieved by reducing the size and volume fraction of shrinkage cavities.

12

Badania technologiczne zgrzewania tarciowego i rezystancyjnego oraz klejenia wybranych gatunków stali i stopów aluminium pod kątem zastosowania w przemyśle zbrojeniowym i transportowym. Zadanie nr 1. Badania technologiczne zgrzewania tarciowego szybkoobrotowego blach pancernych ze stali nanobainitycznych pod kątem zastosowania w przemyśle zbrojeniowym

Węglowska Aleksandra, Michalak Kinga, Rams Beata, Matusiak Jolanta, Pietras Adam, Miara Damian, Pietrzak Jacek, Bryk Robert

Materials Science and Welding Technologies / Technologie Materiałowe i Spawalnicze

|

2025

|

Vol. 69, No. 4

44--48

PL

Badano wpływ parametrów technologicznych zgrzewania tarciowego szybkoobrotowego na jakość złączy wykonanych z blachy ze stali nanobainitycznej i pręta ze stali niestopowej C45 oraz blachy ze stali Armox 560T i pręta ze stali niestopowej C45. Złącza wykonane przy wybranych parametrach zgrzewania poddano badaniom makro- i mikroskopowym, badaniom twardości i wytrzymałości w próbie rozciągania. Na podstawie zarejestrowanych przebiegów drogi skracania, prędkości obrotowej oraz siły docisku analizowano proces zgrzewania. Prowadzono rejestrację przebiegu momentu obrotowego tarcia oraz temperatury obszaru zgrzewania.

EN

The study involved the investigation of the effect of high-speed rotary friction welding parameters on the quality of joints made of nanobainitic steel plates and C45 unalloyed steel bars as well as joints made of Armox 560T steel plates and C45 bars. The joints obtained using selected welding parameters were subjected to macro- and microscopic examinations, hardness measurements and tensile strength tests. The welding process was analysed on the basis of recorded shortening, rotational rate and pressure force. The study also involved the recording of friction torque and the temperature in the welding area.

13

Analiza właściwości tribologicznych stopu Ti13Nb13Zr

Dąbrowski Robert

Inżynieria Materiałowa

|

2025

|

Vol. 46, nr 5

19--23

PL

Celem badań była ocena właściwości tribologicznych medycznego stopu tytanu Ti13Nb13Zr po zaproponowanej obróbce cieplnej, tj. hartowaniu z temp. 800°C i starzeniu w 350, 500 i 650°C. W teście tribologicznym w warunkach tarcia suchego wyznaczono trzy parametry: zużycie masowe, zużycie liniowe i średni współczynnik tarcia. Wykazano, że zastosowanie zabiegu starzenia po hartowaniu i zmiana mikrostruktury stopu od martenzytycznej (α') do dwufazowej (α + β) powoduje zmniejszenie jego zużycia masowego. Ponadto wraz ze wzrostem temperatury starzenia stopu w zakresie 350–650°C odnotowano wzrost współczynnika tarcia w zakresie 0,30–0,40.

EN

The aim of the research was to evaluate the tribological properties of Ti13Nb13Zr medical titanium alloy, after the proposed heat treatment, i.e., hardening from 800°C and aging at 350, 500, and 650°C. In a tribological test under dry friction conditions, three parameters were determined: mass wear, linear wear and average friction coefficient. It has been shown that the application of aging treatment after hardening and changing the alloy microstructure from martensitic (α') to two-phase (α+β) results in a reduction of its mass wear. Furthermore, with increasing aging temperature of the alloy in the range of 350–650°C, an increase in the average friction coefficient was observed, ranging from 0.30 to 0.40.

14

Zirconium dioxide/tungsten carbide composite - influence of sintering technique on phase composition and microstructure

Pędzich Zbigniew, Wilmański Alan, Wojteczko Agnieszka, Komarek Sebastian, Kozień Dawid, Klimczyk Piotr

Composites Theory and Practice

|

2025

|

R. 25, nr 1

30--37

EN

The paper presents the results of a comparative experiment on sintering a particulate composite in the ZrO2/WC system containing significant amounts of carbide additive (20 or 50% by volume) utilizing spark plasma sintering (SPS) or high pressure high temperature (HPHT) techniques. The experiment was conducted using commercial zirconia and tungsten carbide powders. The main aim of the experiment was to verify if it was possible to use the HTHP technique to manufacture composite parts in order to increase the efficiency of the production process. The obtained results showed that the final microstructures of the composites produced by SPS and HPHT differ significantly in their phase composition and microstructure. The materials received by the HPHT process after consolidation contained a large volume of monoclinic zirconia phase, which was a serious disadvantage of the consolidated material due to strong susceptibility to cracking. Furthermore, the short time of sintering prevented the tungsten carbide grains from modifying their shape during the sintering process. The SPS process took more time, but in result the microstructure of the composites contained a non-transformed tetragonal zirconia phase and the carbide grains transformed their shape into convex and isometric ones.

15

Microstructure and selected mechanical properties of hot-rolled AA2024/SiC composite manufactured by powder metallurgy

Nikiel Piotr, Kutyła Patrycja

Composites Theory and Practice

|

2025

|

R. 25, nr 2

102-112

EN

This study investigates the microstructure and mechanical properties of an AA2024/SiC composite produced using powder metallurgy, followed by hot extrusion and multi-pass hot rolling. The composite, containing 5 wt% SiC, was fabricated by hot pressing at 450°C, then extruded and rolled with reductions of up to 66.2%. Microstructural analysis revealed uniform distribution of the SiC particles, grain refinement due to dynamic recrystallization (DRX), and enhanced particle dispersion with increasing rolling reduction. The hardness measurements showed significant improvement, with values increasing from 91 HV1 in the extruded state to 112 HV1 after the final rolling pass, and further grew to 151 HV1 after heat treatment. The tensile tests confirmed a strengthening effect, with the yield stress and ultimate tensile strength rising with rolling reduction from 205 MPa and 304 MPa (after initial rolling) to 236 MPa and 352 MPa (after the final rolling), respectively. Solution treatment and aging of the rolled composite resulted in a sharp increase in yield stress and ultimate tensile strength, reaching 293 MPa and 431 MPa after the first pass, increasing to 375 MPa and 484 MPa after the final pass. The study concludes that hot rolling significantly enhances the mechanical performance of AA2024/SiC composites, with grain refinement and particle fragmentation playing key roles in the strengthening mechanisms.

16

High-entropy alcocufeni matrix composites reinforced with tungsten carbide

Żakowski Michał, Cieślak Grzegorz, Oleszak Dariusz

Composites Theory and Practice

|

2025

|

R. 25, nr 2

75-81

EN

In the present study, metallic-ceramic composites were fabricated, with an equimolar high-entropy AlCoCuFeNi alloy as the matrix, and tungsten carbide WC (5 and 10% by volume) as the reinforcing phase. Induction melting and arc melting techniques were used for composite preparation. The metallic matrix of the composite exhibited a two- phase structure consisting of FCC and BCC solid solutions. Microscopic investigations revealed a dendritic micro- structure of the matrix, in which the WC particles were distributed non-homogeneously, regardless of the melting method. Strong precipitation of the chemical composition in the matrix was observed, with interdendritic regions enriched in copper and dendrites enriched in aluminium, nickel and iron. Additionally, besides WC particles, two types of precipitates, with various morphology, were observed in the matrix. The addition of tungsten carbide particles re- sulted in an increase in the composite hardness from approximately 273 HV for the high-entropy alloy to as high as 332 HV for the composite. The appearance of the precipitates can be attributed to the chemical reaction between the liquid matrix and WC, resulting in the formation of complex carbides.

17

Effect of major alloying elements Zn and Mg on microstructure and microhardness of AA7075 alloys and their composites

Mittal Prachi, Verma Ishu, Tomar Amit, Mahato Jayanta Kumar

Composites Theory and Practice

|

2025

|

R. 25, nr 2

90-101

EN

The present research work focuses on studying the effect of the major alloying elements on the microstructure and hardness of 7xxx series aluminium alloys and their composites. AA7075 aluminium alloy was used as the base material and different weight percentages of alloying elements zinc (Zn) and magnesium (Mg) were added at ratios 1:1, 2:1 and 3:1 to the base material. Afterwards, the modified aluminium alloys were used as matrix materials for the fabrication of aluminium alloy matrix composites (AAMCs) by adding different weight fractions of silicon carbide (SiC) as reinforcement material. Both the alloys and the AAMCs were fabricated by means of stir casting. XRD, SEM and EDX analysis of the modified aluminium alloys and their composites were carried out. Microstructures of the modified aluminium alloys and AAMCs were observed and the grain sizes were measured according to ASTM standards. Hardness tests of the fabricated specimens were carried out using Vickers microhardness testers and the hardness values were measured utilising the integrated software. It was observed that equiaxed grain structures were formed in both the modified Al alloys and their composites, indicating successful fabrication by means of the casting process; however, the average grain sizes of the fabricated specimens are dependent on the combination of wt% of reinforce ment and the composition of the Al alloys. Interestingly, a positive correlation with the weight percent ratio of Zn and Mg in the AA7075 was observed, indicating the potential for fine-tuning of the mechanical properties through proper selection of the alloying elements. It was also observed that the microhardness of the AAMCs fabricated with the mod ified Al alloys exhibits consistent improvement with an increasing weight fraction of SiC reinforcement, irrespective of the weight percentage ratio of the added Zn and Mg combination.

18

Application of AI and machine learning to the theory of composite materials

Mityushev V. V., Nurtazina K. B., Nauryzbayev N. Zh.

Composites Theory and Practice

|

2025

|

R. 25, nr 1

11--20

EN

The homogenization for classifying composites and determining their effective properties is an important optimal design problem of material sciences studied by mathematical modeling. The application of artificial intelligence (AI) and machine learning (ML) in the theory of composite materials is discussed. One of the main problems is the choice of characteristic ML features to describe multi-scale dispersed random composites and to predict their macroscopic properties. The complexity drastically increases when confronted with tasks such as estimating the effective properties of random composites, exploring optimal design scenarios with variable properties of components, or determining the optimal location and shape of inclusions since the myriad use of numerical computations proves challenging due to constraints in time and memory. In such instances, analytical, exact, or approximate formulas with the optimized parameters in symbolic form are preferred because powerful calculus methods can be applied to select the optimal parameters. The present paper is devoted to adequately choosing the parameters called structural sums, and corresponding analytical formulas. Such a formula is often asymptotic, and its correctly determined asymptotic precision shows its application area. We consider the question of the RVE size equivalent to the number of inclusions N per periodicity cell. It can be investigated numerically by solving a periodicity problem with N increasing up to stable effective constants not depending on N . Though one can find works in literature following these lines, they concern special distributions of inclusions with the numerical results performed for small N and for a small number of statistically investigated samples. A comprehensive study of 2D two-phase composites with equal circular inclusions is developed. It is demonstrated that using the concentration of inclusions and a contrast parameter is insufficient to properly study dispersed composites. The method of structural sums in combination with ML to improve model accuracy is applied. Based on the study, a new approach is suggested for selecting optimal parameters to analyze and classify two-dimensional dispersed composite structures. The included content fits 2020 Mathematics Subject Classification: 74Q15, 74-10.

19

Advancing green cement: reaction kinetics and mechanical performance of carbonated wollastonite - limestone-gypsum blended composites for sustainable construction

Praseeda D.

Composites Theory and Practice

|

2025

|

R. 25, nr 3

190--199

EN

With the growing global demand for wollastonite, its potential as a supplementary cementitious material has been explored by inducing carbonation. This study investigates the impact of partially replacing cement with varying amounts of carbonated wollastonite (10-50 wt%) while maintaining a constant proportion of limestone (15 wt%) and gypsum (5 wt%). The developed mixes of blended Portland cement (PC) composites were evaluated for mechanical performance in terms of compressive and flexural strength. The results indicate that the mix containing 20 wt% wollastonite, along with 15 wt% limestone and 5 wt% gypsum, exhibited an approximately 30% higher compressive strength compared to conventional mortar, along with a significant increase of about 62% for the flexural strength. X-ray diffraction (XRD) analysis was performed to assess the phase composition, while thermogravimetric analysis (TGA) quantified the portlandite content and chemically bound water. Microstructural analysis further revealed the formation of the main hydration products such as ettringite, portlandite, and anhydrite enhanced structural integrity. The findings highlight the potential of carbonated wollastonite along with limestone and gypsum in enhancing the mechanical and microstructural properties of the cementitious composites. The mixes with 20 wt% wollastonite along with 15 wt% limestone and 5 wt% gypsum exhibited superior performance compared to other the mixes. However, excessive incorporation resulted in a weakened mechanical performance and microstructure. The findings demonstrate the potential for utilizing carbonated wollastonite in the development of eco-friendly binders, contributing to the reduction in the environmental impact caused by the construction industry.

20

Thermal Effects on the Structural and Mechanical Microstructure Parameters of Siliceous Sandstone from Kielce Upland

Pachnicz Michał

Civil and Environmental Engineering Reports

|

2025

|

Vol. 35, no. 1

250--271

EN

This study explores the thermal evolution of the microstructure and mechanical properties of Jurassic sandstone from the Kielce Upland, subjected to temperatures between 20°C and 1000°C. Combining microcomputed tomography (micro-CT) and nanoindentation techniques, it analyzes how geometric changes affect mechanical parameters. Key features like porosity, pore size distribution, and solid matrix thickness were assessed alongside indentation modulus (MIT) and hardness (HIT). The results reveal a strong correlation between microstructural changes and mechanical responses. At 200°C, microstructural compaction and thermal tightening lead to temporary strengthening. Above 600°C, increased porosity, microcrack formation, and rock matrix degradation cause significant reductions in mechanical properties. Reconstructed grayscale values are identified as reliable estimators for mechanical property changes, particularly for indentation modulus, when baseline parameters are available.