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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

2023

Vol. 68, iss. 3

987-989

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.

Deposition Characteristics of High-Thermal-Conductivity Steel in the Direct Energy Deposition Process and its Hardness Properties at High Temperatures

Son Jong-Youn, Shin Gwang-Yong, Lee Ki-Yong, Yoon Hi-Seak, Shim Do-Sik

Archives of Metallurgy and Materials

2020

Vol. 65, iss. 4

1365--1369

Direct energy deposition (DED) is a three-dimensional (3D) deposition technique that uses metallic powder; it is a multi-bead, multi-layered deposition technique. This study investigates the dependence of the defects of the 3D deposition and the process parameters of the DED technique as well as deposition characteristics and the hardness properties of the deposited material. In this study, high-thermal-conductivity steel (HTCS-150) was deposited onto a JIS SKD61 substrate. In single bead deposition experiments, the height and width of the single bead became bigger with increasing the laser power. The powder feeding rate affected only the height, which increased as the powder feeding rate rose. The scanning speed inversely affected the height, unlike the powder feeding rate. The multi-layered deposition was characterized by pores, a lack of fusion, pores formed by evaporated gas, and pores formed by non-molten metal inside the deposited material. The porosity was quantitatively measured in cross-sectionsof the depositions, revealing that the lack of fusion tended to increase as the laser power decreased; however, the powder feeding rate and overlap width increased. The pores formed by evaporated gas and non-molten metal tended to increase with rising the laser power and powder feeding rate; however, the overlap width decreased. Finally, measurement of the hardness of the deposited material at 25°C, 300°C, and 600°C revealed that it had a higher hardness than the conventional annealed SKD61.

Analysis of the Inhomogeneity of an Electrospun Mat Produced Using Static and Dynamic Collectors of Different Template Design, Including its Mitigation

Pathalamuthu P., Shahana S. T., Nivedha U., Siddharthan A., Giridev V. R.

Fibres & Textiles in Eastern Europe

2017

Vol. 25, no. 3 (123)

53--61

In an electrospinning process, as the deposition of fibres occurs randomly over the collector, the mats produced are generally expected to have homogeneous properties throughout the mat. This study compares the ultimate tensile strength, porosity, thickness and morphology of the different portions of mats sectioned at various angular locations. The influence of the template design and mode of operation of the collectors on the properties of electrospun mats were investigated. The inhomogeneity in the properties of the electrospun mat produced using stationary collectors was significant, irrespective of the different template design of the collectors. However, the collectors operated in the dynamic mode decrease variations in the properties among the different sections of the electrospun mats. By choosing a particular template design and mode of operation of the collector, an electrospun mat of desired orientation can be achieved.

W pracy porównano wytrzymałość na rozciąganie, porowatość, grubość i morfologię różnych fragmentów włóknin wytworzonych przy użyciu kolektorów statycznych i dynamicznych. Zbadano wpływ sposobu działania kolektorów na właściwości otrzymanych włóknin. Zaobserwowano znaczącą niejednorodność właściwości włóknin wytworzonych przy użyciu kolektorów statycznych. Stwierdzono, że kolektory pracujące w trybie dynamicznym zmniejszają odchylenia właściwości pomiędzy różnymi sekcjami włóknin. Poprzez wybranie odpowiedniego sposobu działania kolektora, można uzyskać włókninę o pożądanej orientacji.