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1

New tools for the processing of wood materials in the construction industry

Kruzel Robert, Wachowicz Joanna, Dembiczak Tomasz, Bałaga Zbigniew

Materiały Budowlane

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2025

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nr 10

170--175

EN

Wood-based materials, due to their characteristic features: high resistance to pests; temperature and humidity fluctuations, and relatively low price, are commonly used in both the furniture industry and construction. However, they are difficult to process. They are characterized by varying density in cross-section and contain mineral impurities, which are the main factor causing wear on cutting tools. The article proposes the use of commonly known WC-Co carbides for the machining of chipboard, but obtained using a new FAST (Field Assisted Sintering Technology). The aim of the analyses was to determine the basic durability properties of WC-Co blades and to compare their wear with commercially available carbide blades of similar chemical composition. The tests showed twice the durability of blades made of carbides consolidated with innovative sintering technology.

PL

Materiały drewnopochodne, ze względu na swoje charakterystyczne cechy: dużą odporność na działanie szkodników; wahania temperatury i wilgotności oraz dosyć niską cenę, są powszechnie stosowanym materiałem zarówno w przemyśle meblarskim, jak i w budownictwie. Są one jednak trudne w obróbce. Charakteryzują się zróżnicowaną gęstością w przekroju poprzecznym oraz mają zanieczyszczenia mineralne, które są głównym czynnikiem powodującym zużywanie się narzędzi skrawających. W artykule zaproponowano do obróbki skrawaniem płyt wiórowych, powszechnie znane węgliki WC-Co, ale otrzymywane za pomocą nowej technologii typu FAST (Field Assisted Sintering Technology). Celem analiz było określenie podstawowych właściwości trwałościowych ostrzy WC-Co oraz porównanie ich zużycia do komercyjnie dostępnych ostrzy węglikowych o podobnym składzie chemicznym. Badania wykazały dwukrotnie większą trwałość ostrzy wykonanych z węglików konsolidowanych innowacyjną technologią spiekania.

2

Development of the properties of magnesia alumina spinel-based refractory composites with modifying oxides

Bąk Aleksandra, Surówka Bartosz, Prorok Ryszard, Madej Dominika

Composites Theory and Practice

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2025

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R. 25, nr 3

166--180

EN

The present study investigates the synthesis of MgAl2O4 spinel via one-step sintering, producing a reference sample without additives and four additional samples containing 5 wt% ZrO2, Fe2O3, SiO2, or TiO2, respectively. The MA sample along with the four types of modified spinel-based composites [MA_5T, MA_5Z, MA_5F, MA_5S] were characterized in terms of their phase composition, microstructure, bulk and true densities, as well as open and true porosities of the sintered materials. High-temperature microscopy was employed to evaluate dimensional changes of the samples during their heat treatment process. The presence of phases and the firing behavior of the resulting composite materials were evaluated using thermodynamic simulation (FactSage 8.3). The study demonstrated that the incorporation of specific oxide additives significantly influences the synthesis and properties of MgAl₂O₄ spinel. Iron (Fe³⁺) and titanium (Ti⁴⁺) ions were found to induce structural modifications within the spinel lattice, suggesting partial substitution or incorporation into the crystal framework. XRD analysis showed that the addition of the SiO₂ modifier leads to the formation of Mg₂SiO₄, which can partially dissolve into the spinel phase, while ZrO₂ promoted the extraction of Al³⁺ ions from the spinel structure, as corroborated by the thermochemical simulations using FactSage. The highest microstructural densification was achieved in the samples with TiO₂ and SiO₂, indicating their positive role in enhancing sintering efficiency. Conversely, the addition of Fe₂O₃ did not significantly affect the densification behavior, despite the formation of an Fe-rich spinel phase.

3

Application of thermodynamic equilibrium modelling to predict slagging and fouling tendencies of bituminous coal and wheat straw blends

Król Karol, Nowak-Woźny Dorota, Janiczek Tomasz

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2025

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Vol. 73, nr 1

art. no. e152604

EN

The combustion or co-combustion of biomass or alternative fuels is important in the energy sector because of the need to reduce the share of fossil fuels. This article is a continuation of previous studies on the behaviour of the mineral matter of selected fuels during the sintering processes. The blends of wheat straw biomass from Polish crops (WS) with bituminous coal from the Makoszowa mine (BC) were studied. The study included proximate and ultimate analysis and oxide analysis of ash blends with the following composition: 10wt% WS/90wt%BC, 25wt% WS/75wt%BC, and 50wt% WS/50wt%BC. Based on the oxide content, a prediction (using FactSage 8.0 software) of the sintering process of the mixtures was tested. The following parameters were determined: slag phase content, specific heat at constant pressure, and ash density. The fracture stress tests were carried out using the mechanical test. Pressure tests were also performed using the pressure drop test method. The test results of all test methods used were compared with each other. Based on this comparison, a clear correlation was found between the sintering temperatures determined by the mechanical method and the pressure drop method and the physical properties of the ashes, such as density and heat capacity, as well as the chemical properties, i.e. the content of the slag phase. The results of the presented research are a valuable addition to the previous work of the authors. The goal of this work is to develop a precise and measurably simple method to determine the sintering temperature of ashes. This is an extremely important issue, especially in the case of the need to use a wide range of fuels in the energy industry.

4

Phase Transition Enthalpy, and Oxidation Binding Energy of Hydrothermally Synthesized BaTiO3 Nanopowders via Pre-annealing and Sintering Processes

Lee Jongbeom, Jeong Jinyoung, Jung Jaehoon, Jeong Haguk

Archives of Metallurgy and Materials

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2025

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Vol. 70, iss. 2

733--736

EN

Hydrothermally synthesized BaTiO3 nanopowders pre-annealed at high temperatures of 900℃ for 4 h in the air were sintered at 1200℃ for 2 h in N2 atmosphere, and their cubic-tetragonal transformation, transition enthalpy, and binding energy (BE) were investigated. The nanopowder crystal structures changed from cubic to tetragonal during annealing or sintering at temperatures above 900℃ with constant tetragonality (1.01). With increasing pre-annealing temperature, the cubic-tetragonal transition enthalpy decreased, and the differential scanning calorimetry (DSC) peak broadened. Pre-annealing in the air increased BE and nonchemical energy distribution in the BaTiO3 powder, reducing the transition enthalpy and sharpness of the DSC curve. This was ascribed to the differences in imperfections from oxidation, such as the density and uniform distribution of Ba among the samples, resulting from the BE shifts of the Ba 3d, Ti 2p and O 1s peaks to higher values in the XPS spectra.

5

Optimizing Dielectric Constant in Tetragonal BaTiO3 Via Densification, Tetragonality, and Grain Growth Kinetic with Sintering Temperature

Lee Jongbeom, Jeong Jinyoung, Jung Jaehoon, Jeong Haguk

Archives of Metallurgy and Materials

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2025

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Vol. 70, iss. 2

765--769

EN

Tetragonal BaTiO3 nanopowders with tetragonality (c/a = 1.01), compacted uniaxially at 300 MPa, underwent sintering at temperatures ranging from 900°C to 1200°C for 1 h. Their densification and microstructure evolution were examined to determine the dielectric constant as a function of temperature (25-150°C) and frequency (102-107 Hz). Increasing the sintering temperature enhanced the densification and grain growth of BaTiO3, demonstrating a linear relationship between them. However, the tetragonality remained unaffected by the sintering temperature. The densified BaTiO3 exhibited a high dielectric constant (εr) across temperatures and frequencies. The activation energy for grain growth varied depending on the primary mechanism of lattice and grain boundary diffusion, ranging approximately from 119.1 to 172.5 kJ/mol across the entire sintering range.

6

Improving the permeability characteristic of nickle oxide/yttria stabilized zirconia anode through thermal decomposition of organic porous support as sustainable material for green hydrogen ecosystem

Febriandyono Muhammad Faesal, Sulistyo, Tauviqirrahman Mohammad, Calista Rayhan, Rahman Reza Abdu

Advances in Science and Technology. Research Journal

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2025

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Vol. 19, no. 4

270--279

EN

Modification of the anode for fuel cell is essential to achieve the effective conversion rate at desired level. It is influenced by the gas distribution during the process. The compact profile of the anode is a direct impact for using sintering as reliable production method, making further material modification is demanded to solve the issue. At this work, practical solution is conducted to maintain the effective gas diffusion for anode, which is achieved through surface decoration enhancement. The study uses organic porous support (PS) as one sustainable and applicable method. The organic PS is made from flour, which evaporates during the sintering process. The diffraction profile for the produced anode indicates no substantial changes in the structural and physical characteristics. The morphology observation implies various models on the pore formation, including an elongated gap, achieved by a higher PS ratio (15 wt%). It promotes the highest permeability up to 0.425 m2, with maximum partial pressure difference only 4.53 kPa. It shows the achievement of surface modification is reliable to provide substantial improvement on the gas distribution throughout the conversion process. Thus, the contribution of this work is possible for applied as reliable method to improve the pores formation.

7

The effect of composition and holding time on glaze production using basalt rock as a base

Birawidha David Candra, Miswanto Agus, Setiawan Liston, Prakosa Agus, Dani Umar, Gunawan Gunawan, Arianti Era, Karo-Karo Pulung, Nugroho Totok, Hendronursito Yusup

Physicochemical Problems of Mineral Processing

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2024

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Vol. 60, iss. 1

art. no. 177640

EN

This research studied the potential use of local basalt and feldspar from Lampung Province, Indonesia, as glaze materials. Frit(s) are composed of changing basalt-to-feldspar weight ratios of A (30:70), B (50:50), C (70:30), and D (100:0) w/w%. The added 20% boric acid to the total weight reduces the process temperature to 1,000oC with holding times of 1, 4, and 8 hr(s). Based on the chemical composition test of the specimen, the four variations of the sample have SiO2 content above 40%, and the average SiO2/Al2O3 ratio is 4 and 5, which is usually a low-alumina glaze that will cause a glossy effect and have an amorphous structure. At point 2theta 29o, amorphous forms. Quartz (SiO2), albite (NaAlSi3O8), anorthite (CaAl2Si2O8), and coesite (SiO2) phases were discovered in the glaze specimens. The anorthite phase in glass-ceramic glaze gives a transparent glaze color due to the amorphous glassy phase formed during heat treatment. The findings of this study suggest that local materials based on basalt and feldspar may be used as glaze materials to provide a smooth texture and surface; the glaze layer is evenly distributed, can follow the full surface contour of the test specimen, and has low porosity.

8

Refractory metals as alloying additives for metallic materials formed via powder metallurgy techniques

Duda Alicja, Kopyciński Bartosz, Matula Grzegorz, Wrona Adriana

Ochrona przed Korozją

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2024

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nr 3

68--76

EN

Methods for the fabrication of metallic sinters via powder metallurgy techniques have been widely discussed in materials engineering for many years. Depending on the final purpose of the finished products, it is primarily important to ensure their appropriate mechanical properties. Numerous works on this topic are devoted mainly to the modification of conventional metallic materials, and one of the promising research directions is the addition of refractory metals to metal alloys. Thanks to the advantageous impact on thermal stability, mechanical properties, and corrosion resistance, the proposed solutions fit perfectly into the trends of searching for new, functional engineering materials. This work presents a review of scientific reports on the modification of metal alloys with the addition of refractory metals published over the last 15 years. First, a brief characterization of refractory metals along with a description of the basics of processing metallic materials using powder metallurgy are presented. In the following part of the article, the research results on the influence of the addition of high-melting metals on the mechanical properties and corrosion resistance of heavy and light metal alloys are discussed. The conclusion consists of data on the global metal alloys market, taking into account its current state and forecasted changes for the next few years.

PL

Metody spieków metalicznych technikami metalurgii proszków są szeroko omawiane w inżynierii materiałowej od wielu lat. Niezależnie od przewidywanego przeznaczenia gotowych wyrobów istotne jest przede wszystkim zapewnienie produktom odpowiednich własności mechanicznych. Liczne prace poświęcone tej tematyce skupiają się głównie na modyfikacji konwencjonalnych materiałów metalicznych, a jednym z obiecujących kierunków badań jest wzbogacanie stopów metali dodatkiem metali wysokotopliwych. Dzięki korzystnemu wpływowi na stabilność termiczną, własności mechaniczne i odporność na korozję proponowane rozwiązania doskonale wpisują się w poszukiwania nowych, funkcjonalnych materiałów inżynierskich. Praca stanowi przegląd doniesień naukowych opublikowanych w ciągu ostatnich 15 lat, traktujących o modyfikacji stopów metali dodatkiem metali wysokotopliwych. W pierwszej kolejności przedstawiono krótką charakterystykę metali wysokotopliwych wraz z omówieniem podstaw przetwarzania materiałów metalicznych z wykorzystaniem metalurgii proszków. W dalszej części artykułu przeprowadzono analizę wyników badań nad wpływem dodatku metali wysokotopliwych na własności mechaniczne oraz odporność korozyjną stopów metali ciężkich i lekkich. W podsumowaniu przybliżono dane dotyczące stanu globalnego rynku stopów metali wraz z uwzględnieniem zmian prognozowanych na najbliższe lata.

9

Wpływ odpadów szklistych na proces spiekania klinkieru portlandzkiego

Wons Wojciech, Rzepa Karol, Reben Manuela

Cement Wapno Beton

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2024

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R. 29, nr 6

362--379

PL

Głównym wyzwaniem europejskiego przemysłu cementowego ostatniej dekady jest tzw. dekarbonizacja, czyli ograniczenie emisji CO2 w całym cyklu produkcyjnym. W przypadku przemysłu cementowego zadanie to jest o tyle trudne, że większość emisji CO2 pochodzi z dysocjacji termicznej kalcytu obecnego w surowcach do produkcji klinkieru portlandzkiego. Głównym sposobem ograniczenia emisji CO2 z tego źródła jest wykorzystanie nośników tlenku wapnia w formie niewęglanowej. W praktyce jednak dostępność takich surowców w Europie jest bardzo ograniczona, a ich import z innych kontynentów jest nie tylko nieopłacalny, ale również nieekologiczny ze względu na emisje generowane podczas transportu. Istnieją jednak przykłady wykorzystania surowców odpadowych zawierających tlenek wapnia w produkcji klinkieru portlandzkiego. Należą do nich m.in. granulowany żużel wielkopiecowy, żużle konwertorowe, wapno pokarbidowe, popioły wapienne, a także stłuczka szklana będąca przedmiotem analiz. Celem badań jest analiza spiekalności klinkierów z dodatkiem różnych odpadów szklistych. Wybrano te odpady szkliste, które ze względu na zanieczyszczenia i drobnoziarnistą postać nie mogły być ponownie wykorzystane w produkcji szkła. Zastosowanie stłuczki szklanej było ilościowo ograniczone ze względu na dużą zawartość Na2O [13% -15%]. Odpady szkliste wprowadzone do zestawu surowcowego są głównie nośnikiem SiO2 [67% - 69%] oraz w mniejszym stopniu CaO [9,0% - 12,4%]. Wprowadzenie nawet niewielkich ilości stłuczki podnosi zapotrzebowanie na surowiec wysokowapienny a także surowce będące nośnikiem Al2O3 i Fe2O3. Mimo, że odpady szkliste wprowadzają CaO w formie niewęglanowej to wymienione zmiany w nadawie surowcowej w połączeniu z obecnością w surowcach innych niż kalcyt węglanów (dolomit, syderyt) sprawiają, że dodatek stłuczki szklanej nie koniecznie powoduje ograniczenie emisji surowcowej CO2. Pozytywny wpływ dodatku odpadów szklistych na spiekalność zestawów surowcowej jest zauważalny w temperaturach 1200°C - 1250°C. Prawdopodobnie jest on związany z dużą zawartością Na2O w odpadach szklistych oraz ich amorficzną formą.

EN

The main challenge for the European cement industry in the last decade is so-called decarbonisation, i.e. reducing CO2 emissions throughout the entire production cycle. In the case of the cement industry, this task is difficult because most CO2 emissions come from the thermal dissociation of calcite present in raw materials for the production of Portland clinker. The main way to reduce CO2 emissions from this source is to use calcium oxide sources in non-carbonate form. In practice, however, the availability of such raw materials in Europe is very limited, and their import from other continents is not only unprofitable, but also environmentally unfriendly due to emissions generated during transport. However, there are examples of the use of waste raw materials containing calcium oxide in the Portland clinker production. These include, among others, granulated blast furnace slag, converter slag, carbide lime, lime ash, as well as glass cullet which is the subject of analyses. The aim of the research is to analyse the burnability of clinkers with the addition of various glass wastes. The glass wastes selected were those that could not be reused in glass production due to contamination and fine-grained form. The use of glass cullet was quantitatively limited due to the high Na2O content [13 % -15 %]. Glass waste introduced into the raw material batch is mainly a source of SiO2 [67 % - 69 %] and to a lesser extent CaO [9.0 % - 12.4 %]. The introduction of even small amounts of cullet increases the demand for high-lime raw material and also raw materials that are sources of Al2O3 and Fe2O3. Although glass waste introduces CaO in a non-carbonate form, the above changes in the raw material feed combined with the presence of carbonates in raw materials other than calcite [dolomite, siderite] mean that the addition of glass cullet does not necessarily reduce CO2 emissions from raw materials. The positive effect of the addition of glass waste on the burnability of raw material batches is noticeable at temperatures of 1200 °C - 1250 °C. It is probably related to the high Na2O content in the glassy waste and its amorphous form.

10

Effect of U-FAST Technology on Basic Properties of WC-Co Composites Designed for Particleboard Milling Tools

Wachowicz Joanna, Bałaga Zbigniew, Dembiczak Tomasz, Náprstková Nataša, Kuśmierczak Sylvia

Biuletyn Wojskowej Akademii Technicznej

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2024

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Vol. 73, nr 2

9--13

EN

Cemented carbides WC-Co are one of the basic tool materials. They constitute over half of the currently used tools intended for machining. The main advantages of WC-Co cemented carbides are their high hardness and abrasion resistance. The properties of WC-Co sinters depend mainly on the content of the binding phase, the sintering method, and the grain size of the powder from which the sinters were made. The aim of the study was to produce WC-Co nanocomposites using U-FAST (Upgraded Field Assisted Sintering Technology), as well as to examine the basic properties of WC-Co sinters: microstructure, hardness, and phase composition. In the sintering processes carried out, no additives affecting the reduction of grain growth were used. The obtained results were compared with similar sinters produced using SPS (Spark Plasma Sintering) technology.

PL

Węgliki spiekane WC-Co są jednym z podstawowych materiałów narzędziowych. Stanowią ponad połowę obecnie stosowanych narzędzi przeznaczonych do obróbki skrawaniem. Głównymi zaletami węglików spiekanych WC-Co są wysoka twardość i odporność na ścieranie. Właściwości spieków WC-Co zależą głównie od zawartości fazy wiążącej, metody spiekania i wielkości ziarna proszku, z którego wykonano spieki. Celem badań było wytworzenie nanokompozytów WC-Co przy użyciu technologii U-FAST (Upgraded Field Assisted Sintering Technology), a także zbadanie podstawowych właściwości spieków WC-Co: mikrostruktury, twardości, składu fazowego. W przeprowadzonych procesach spiekania nie stosowano dodatków wpływających na ograniczenie rozrostu ziarna.

11

The Effects of CaO and MgO on Thermal, Mechanical and Optical Properties of Porcelain Tiles by Utilizing Blast Furnace Slag

Aydin Tuna, Sari Hasan

Archives of Metallurgy and Materials

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2024

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Vol. 69, iss. 4

1501--1508

EN

In this study, the Blast Furnace Slag (BFS) of Zonguldak Eregli Iron and Steel Factories was used as a recycling raw material for the porcelain tile samples. A kind of clay with high MgO content was also used in the porcelain tile recipes. Maximum 10% of BFS was used instead of Na-feldspar. Sintering temperature for all samples was 1205°C for 50 minutes in the industrial roller kiln. Technological properties such as shrinkage, water absorption, colour measurement, and flexural strength were investigated as well as sintering properties and microstructures of the green and the sintered samples. As a result of the study, the addition of BFS did not adversely affect the technical properties of porcelain tile bodies. Particularly, the addition of BFS up to 3% contributed to an increase in flexural strength, and whiteness values of all samples increased because of the formation of anorthite and diopside compared to the reference body. The phase transformations and crystal formations such as anorthite and diopside resulted in a decrease in the ﬁring shrinkage. Although the anorthite formation and diopside formation in the investigated samples had an adverse effect on condensation, it was found that they showed similar sintering behaviours compared to the reference body. This study showed that an industrial waste material can be converted into an environmentally friendly raw material that can create added value and provide energy efficiency.

12

Sinterability, Microstructural Evolution, and Dielectric Performance of Bismuth Sodium Titanate (Bi0.5Na0.5TiO3) Lead-Free Ferroelectric Ceramics

Takiul Islam, Lee Sanghaw, Hwang Haejin

Archives of Metallurgy and Materials

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2024

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Vol. 69, iss. 1

33--38

EN

In this study, lead-free bismuth sodium titanate (BNT; Bi0.5Na0.5TiO3) powder was synthesized using wet precipitation. The sintering behavior and dielectric properties of the BNT ceramics were investigated in terms of the sintering temperature. Titanium isopropoxide, sodium nitrate, and bismuth nitrate were used as starting materials. A titanium peroxo complex (TPC) solution was synthesized using titanium hydroxide, nitric acid, and hydrogen peroxide. A clear Bi-Na-Ti precursor solution was obtained by mixing the TPC, sodium, and bismuth nitrate solutions. The pH of the precursor solution was increased to 9 using NaOH and a white powder was precipitated. A spherical and pyrochlore phase-free BNT powders were obtained by calcining the white precipitate above 600°C for 3 h. Particle size analysis and SEM observations revealed that the BNT powder calcined at 700°C exhibited homogeneous distribution with particle size less than 300 nm. The sinterability of the BNT ceramic prepared through wet precipitation was significantly enhanced compared to that of the BNT powder prepared via the solid-state reaction of sodium carbonate, bismuth oxide, and titanium oxide powders.

13

Fabrication of Porous Sintered Body using Shape-Controled 316l Stainless Steel Powder by High-Energy Ball Milling

Kim Woo Cheol, Byun Jongmin

Archives of Metallurgy and Materials

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2024

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Vol. 69, iss. 1

109--112

EN

In this study, 316L stainless steel powder was used to produce a porous body that could be used in a specific environment. In contrast to the existing method of producing filters using only spherical powders, we attempted to produce filters using plate- and needle-like powders and evaluated their performance. In the powder preparation step, the shape change of the powder was analyzed by changing the size of the stainless-steel balls used for ball milling. Then, the variations in properties of the sintered porous body caused by the ball size were investigated. As the average ball size decreased, the average particle size of the powder decreased. Moreover, the surface area and pore size of the porous body decreased. Additionally, when balls of different sizes were mixed, the porous body showed a mixture of coarse and fine pores.

14

Development of NdYO3 Powder Fabrication as a Reaction Preventing Raw Material for Metal Fuel Casting

Park Sang-Gyu, Kim Ki-Hwan, Kim Jun Hwan

Archives of Metallurgy and Materials

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2024

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Vol. 69, iss. 2

429--432

EN

Metal fuel is a promising candidate for the pyro-processed nuclear fuel, but the problem of loss of nuclear material due to the high reactivity of metal fuel and melting crucible in the metal fuel casting process must be solved for loss control and waste reduction. In this study, fabrication test was conducted to develop a new material NdYO3 as a new crucible material to improve the degree of anti-reactivity. The NdYO3 compact was manufactured by the CIP (Cold isostatic pressing) method with changing fraction of Nd3O3 and Y2O3 powders. Sintering process was performed at 1550°C for 10 hours. The systematic trends of XRD patterns shows that phase transformations form cubic structure to monoclinic structures occurred with the addition of Y2O3. The rate of pore were discussed with change of fraction of Nd2O3 and Y2O3.

15

Badania nad przygotowaniem nowego ekologicznego granulatu ceramicznego dla budownictwa

Wang Yifei

Przemysł Chemiczny

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2023

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T. 102, nr 8

795--798

PL

Poferment z fermentacji biomasy (DR) i popiół lotny (FA) zmieszano z biowęglem z osadów ściekowych (SSC) w stosunku 10:10:80 i spiekano w temp. 1050°C. Produkt został zgranulowany z przeznaczeniem na materiały budowlane i przetestowany zgodnie z chińskimi normami krajowymi. Wszystkie wskaźniki jakości granulatu spełniły wymagania chińskich norm krajowych dla granulatu budowlanego. Wskaźnik potencjalnego ryzyka ekologicznego związanego z obecnością metali ciężkich był niski, a produkt był bezpieczny.

EN

Biomass fermentation digestate and fly ash were mixed with sludge biochar in the ratio of 10:10:80 and sintered at 1050°C. The product was pelletized to building materials and tested according to China national stds. All the qual. indicators of the pellets met the requirements of the China national stds. for construction pellets. The potential ecol. risk index of heavy metals was low, and the product was safe.

16

Phase transformations in Ni-rich additively manufactured NiTi alloys

Ratajski Jerzy, Bałasz B., Mydłowska K., Pancielejko Mieczysław, Laskowska D., Szparaga Łukasz

Journal of Achievements in Materials and Manufacturing Engineering

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2023

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Vol. 121, nr 1

118--130

EN

The objective of the research outlined in the article was to evaluate the conventional parameter known as volumetric energy density (VED), which serves as the primary indicator determining the quality of products manufactured using the additive technique with the Selective Laser Sintering (SLS) method. An independent goal was to examine the impact of secondary phase precipitates (Ni4Ti3) on the temperature ranges of phase transformations in nickel-rich NiTi alloys. Design/methodology/approach The assessment of Volumetric Energy Density (VED), was conducted based on the measurement of sample density, analysis of phase transformation sequences determined by scanning differential calorimetry (DSC), and phase composition determined by X-ray diffraction (XRD). VED was calculated based on laser power, scanning speed, hatch spacing, and single-layer thickness in the study on the influence of secondary phase precipitates (Ni4Ti3), formed during the ageing of the samples at 500°C for 20 and 100 hours, on the sequence of phase transformations, as well as the initiation and completion temperatures of martensitic (Ms, Mf) and austenitic (As, Af) transformations, scanning differential calorimetry (DSC) and X-ray diffraction (XRD) were employed. Findings It has been demonstrated that the value of Volumetric Energy Density (VED) is not a decisive parameter for the quality of the result. The primary influences on the quality of samples after the SLS process were found to be the laser energy and hatching space values. By varying the ageing time at a temperature of 500°C for NiTi alloy samples with excess nickel content (51.7 at.%), it is possible to influence the temperature of thermoelastic martensitic transformation effectively. This allows for utilising its unique functional properties for various advanced applications. Research limitations/implications The absolute condition for determining the temperature and post-processing time, which dictates specific phase transformation temperatures in NiTi alloys produced by additive techniques (SLS), is the selection of process parameters. The parameters include laser power and hatch spacing, ensuring an appropriate scanning speed and layer thickness. The factors guarantee certain product properties characterised by specific density and direct austenite-to-martensite transformation occurring during the cooling of samples. Practical implications Influencing the Ni/Ti ratio and microstructure of NiTi alloy through appropriate post-processing allows for the utilisation of its functional features, such as the shape memory effect combined with superelasticity, for advanced applications. Originality/value Based on the conducted research, it has been demonstrated that the quality of the product after the SLS process primarily depends on laser power and hatch spacing. It has also been shown that, for precise tuning of phase transformation temperatures in additively manufactured NiTi alloys, the selection of post-processing parameters is essential and is influenced by the initial composition of the powder used.

17

Effect of sintering temperature and isostatic pressure on selected properties of selected electrical contact materials manufactured by hot isostatic pressing

Kołacz Dariusz, Kulasa Joanna, Krukowski Karol, Hury Anna, Muzia Grzegorz, Osadnik Małgorzata, Kalabis Jarosław

Composites Theory and Practice

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2023

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R. 23, nr 2

67--75

EN

This paper presents the results of studies on the consolidation of metallic and composite powders by the hot isostaticpressing (HIP) process intended for electrical contact materials. Ag, Cu metallic powders, as well as AgW48Re2, AgRe1 and CuW47Re3 composite powders were used in the investigations. Green compacts for consolidation and hot sintering under pressure were prepared by double-sided axial pressing in steel dies. The density, electrical conductivity, and hardness were measured on the obtained sinters after the HIP process, and the microstructure was examined on selected ones. The research indicates that applying this technology allows good quality electrical material to be obtained, intended for electrical contact material.

18

Influence of Sintering Temperature on the Pore Structure of an Alkali-Activated Kaolin Based Geopolymer

Ramli Mohd Izrul Izwan, Salleh Mohd Arif Anuar Mohd, Aziz Ikmal Hakem, Zaimi Nur Syahirah Mohamad, Amli Siti Farahnabilah Muhd, Abdullah Mohd Mustafa Al Bakri

Archives of Metallurgy and Materials

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2023

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Vol. 68, iss. 3

987-989

EN

Kaolin-based geopolymers are alternatives for producing high-strength ceramics for construction materials. Creating high-performing kaolin ceramics utilizing the regular technique requires a high handling temperature (higher than 1200°C). Thus, the structure and properties such as pore size and distribution are affected at higher sintering temperatures. Along these lines, information with respect to the sintering system and related pore structure is essential for advancing the properties of the previously mentioned materials. This study investigated the microstructure and the density of a kaolin-based geopolymer at various sintering temperatures. The unsintered sample has the highest density of 1610 kg/cm3 , while the samples sintered at 1100°C haves the lowest density of 1203 kg/cm3 . The result also shows that increasing the sintering temperature to 1100°C resulted in increasing the water absorption of the kaolin-based geopolymer ceramic.

19

Influence of Dissolved Oxygen Content on the Properties of Aqueous Milled WC-Co Powders

Chicinas Horea F., Marton Leó-Ede, Popa Catalin O.

Archives of Metallurgy and Materials

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2023

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Vol. 68, iss. 3

1205--1210

EN

The research aims to develop a novel and safer milling route to produce Hard Metals. Considering the risks associated with milling fine particles under organic solvents, especially the increased fire and explosion risks, we propose milling under aqueous milling media to diminish the risks associated with fire hazards, while maintaining the oxidation level at a minimum. The samples were sintered in an industrial sintering oven under vacuum at 1380°C subsequent to milling and drying. The characterisation of the materials has been done by X-ray diffraction, scanning electron microscopy, particle size analysis, optical microscopy, and a magnetometer. The obtained results indicate that appropriate properties of the powders after milling and drying as well as the desired biphasic (Co-WC) phases were obtained after sintering, thus proving the feasibility of such a route and diminishing specific fire hazards.

20

Effect of calcite and mica contents in nepheline syenite samples on the ceramic body sintering behaviours and surface roughness

Durgut Emrah, Cinar Mustafa, Ozdemir Orhan

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 5

art. no. 149179

EN

In this study, the effects of calcite and mica contents in nepheline syenite (NS) samples beneficiated by high intensity dry magnetic separation and flotation methods on ceramic bodies were investigated in detail. The NS samples were, first, sintered to observe the physical and surface roughness properties, and characterized based on the change of NS samples such as color, shrinkage, water absorption, and surface roughness after the sintering process. L-a-b color and Ra, Rz, Rt values for the NS samples were determined. The decrease in calcite and mica contents affected the surface of sintered specimens positively by reducing roughness values. Additionally, the water absorption values were found to be directly proportional to Ra values for unglazed surfaces. In conclusion, calcite and mica minerals in NS samples negatively affected surface quality by forming pinholes due to dehydroxylation and outgassing reactions in the sintering process.