• Research Paper

    Quality Improvement of Crude Glycerol from Biodiesel Production Using Activated Carbon Derived from Krabok (Irvingia malayana) Seed Shells
    Wuttichai Roschat, Sarunya Donrussamee, Phatcharanan Smanmit, Samlit Jikjak, Tappagorn Leelatam, Sunti Phewphong, Krittiyanee Namwongsa, Preecha Moonsin, and Vinich Promarak
    This research investigated the preparation of activated carbon derived from Krabok (Irvingia malayana) seed shells to improve the quality of … + READ MORE
    This research investigated the preparation of activated carbon derived from Krabok (Irvingia malayana) seed shells to improve the quality of crude glycerol obtained during biodiesel production. The activated carbon was prepared using a dry chemical activation method with NaOH, utilizing an innovative biomass incinerator. The results revealed that the resulting KC/AC-two-step exhibited favorable physicochemical adsorption properties, with a high surface area of 758.72 m2/g and an iodine number of 611.10 mg/g. These values meet the criteria of the industrial product standard for activated carbon No. TIS 900-2004, as specified by the Ministry of Industry in Thailand. Additionally, the adsorption efficiency for methylene blue reached an impressive 99.35 %. This developed activated carbon was then used to improve the quality of crude glycerol obtained from biodiesel production. The experimental results showed that the KC/AC-two-step increased the purity of crude glycerol to 73.61 %. In comparison, commercially available activated carbon (C/AC) resulted in a higher crude glycerol purity of 81.19 %, as analyzed by the GC technique. Additionally, the metal content (Zn, Cu, Fe, Pb, Cd, and Na) in purified glycerol using KC/AC-two-step was below the standards for heavy metals permitted in food and cosmeceuticals by the Food and Drug Administration of Thailand and the European Committee for Food Contact Materials and Articles. As a result, it can be inferred that Krabok seed shells have favorable properties for producing activated carbon suitable as an adsorbent to enhance crude glycerol purity. Furthermore, the improved crude glycerol from this research has potential for various industrial applications. - COLLAPSE
    27 January 2024
  • Research Paper

    Preparation and Performance of Aluminosilicate Fibrous Porous Ceramics Via Vacuum Suction Filtration
    Qingqing Wang, Shaofeng Zhu, Zhenfan Chen, and Tong Zhang
    This study successfully prepared high-porosity aluminosilicate fibrous porous ceramics through vacuum suction filtration using aluminosilicate fiber as the primary raw material and … + READ MORE
    This study successfully prepared high-porosity aluminosilicate fibrous porous ceramics through vacuum suction filtration using aluminosilicate fiber as the primary raw material and glass powder as binder, with the appropriate incorporation of glass fiber. The effects of the composition of raw materials and sintering process on the structure and properties of the material were studied. The results show that when the content of glass powder reached 20 wt% and the samples were sintered at the temperature of 1,000 °C, strong bonds were formed between the binder phase and fibers, resulting in a compressive strength of 0.63 MPa. When the sintering temperatures were increased from 1,000 °C to 1,200, the open porosity of the samples decreased from 89.08 % to 82.38 %, while the linear shrinkage increased from 1.13 % to 10.17 %. Meanwhile, during the sintering process, a large amount of cristobalite and mullite were precipitated from the aluminosilicate fibers, which reduced the performance of the aluminosilicate fibers and hindered the comprehensive improvement in sample performance. Based on these conditions, after adding 30 wt% glass fiber and being sintered at 1,000 °C, the sample exhibited higher compressive strength (1.34 MPa), higher open porosity (89.13 %), and lower linear shrinkage (5.26 %). The aluminosilicate fibrous porous ceramic samples exhibited excellent permeability performance due to their high porosity and interconnected three-dimensional pore structures. When the samples were filtered at a flow rate of 150 mL/min, the measured pressure drop and permeability were 0.56 KPa and 0.77 × 10-6 m2 respectively. - COLLAPSE
    27 January 2024
  • Research Paper

    Synthesis and Analysis of the Impact of Partial Mercury Replacement with Lead on the Structural and Electrical Properties of the Hg1-xPbxBa2Ca2Cu3O8+δ Superconductor
    Kareem Ali Jasim, Chaiar Abdeen Zaynel Saleh, and Alyaa Hamid Ali Jassim
    In this investigation, samples of the chemical (Hg1-xPbxBa2Ca1.8Mg0.2Cu3O8+δ) … + READ MORE
    In this investigation, samples of the chemical (Hg1-xPbxBa2Ca1.8Mg0.2Cu3O8+δ) were prepared utilizing a solid-state reaction technique with a range of lead concentrations (x = 0.0, 0.05, 0.10, and 0.20). Specimens were pressed at 8 tons per square centimeter and then prepared at 1,138 K in the furnace. The crystalline structure and surface topography of all samples were examined using X-ray diffraction (XRD) and atomic force microscopy (AFM). X-ray diffraction results showed that all of the prepared samples had a tetragonal crystal structure. Also, the results showed that when lead was partially replaced with mercury, an increase in the lead value impacted the phase ratio, and lattice parameter values. The AFM results likewise showed excellent crystalline consistency and remarkable homogeneity during processing. The electrical resistivity was calculated as a function of temperature, and the results showed that all samples had a contagious behavior, as the resistivity decreased with decreasing temperature. The critical temperature was calculated and found to change, from 102, 96, 107, and 119 K, when increasing the lead values in the samples from 0.0 to 0.05, 0.10, and 0.20, respectively. - COLLAPSE
    27 January 2024
  • Research Paper

    Comparative Analysis of Commercial Al2O3 Powders and the Dispersion Characteristics of Slurries Produced Using Them

    상용 Al2O3 분말의 비교분석 및 이를 이용하여 제조한 슬러리의 분산 특성

    Mo-Se Kwon, Seung-Joon Yoo, Jin-Ho Kim, Kyoung-Hoon Jeong, Jong-Keun Lee, and Ung-Soo Kim

    권모세, 유승준, 김진호, 정경훈, 이종근, 김응수

    Al2O3 has excellent sintering properties and is important in semiconductor manufacturing processes that require high-temperature resistance and chemical inertness … + READ MORE
    Al2O3 has excellent sintering properties and is important in semiconductor manufacturing processes that require high-temperature resistance and chemical inertness in a plasma environment. In this study, a comprehensive analysis of the chemical characteristics, physical properties, crystal structure, and dispersion stability of three commercially available Al2O3 powders was conducted. The aim was to provide a technological foundation for selecting and utilizing appropriate Al2O3 powders in practical applications. All powders exhibited α-Al2O3 as the main phase, with the presence of beta-phase Na2O-11Al2O3 as the secondary phase. The highest Na+ ion leaching was observed in the aqueous slurry state due to the presence of the secondary phase. Although the average particle size difference among the three powders was not significant, distinct differences in particle size distribution were observed. ALG-1SH showed a broad particle size distribution, P162 exhibited a bimodal distribution, and AES-11 displayed a uniform unimodal distribution. High-concentration Al2O3 slurries showed differences in viscosity due to ion release when no dispersant was added, affecting the electrical double-layer thickness. Polycarboxylate was found to effectively enhance the dispersion stability of all three powders. In the dispersion stability analysis, ALG-1SH exhibited the slowest sedimentation tendency, as evidenced by the low TSI value, while P162 showed faster precipitation, influenced by the particle size distribution. - COLLAPSE
    27 January 2024
  • Research Paper

    Application to Piezoelectric and Triboelectric Generators of Spongy Structured BaTiO3 Prepared by Sputtering

    Sputtering에 의해 제조된 해면 구조 BaTiO3의 압전 및 마찰전기 발전기에의 응용

    Seon-A Kim and Sang-Shik Park

    김선아, 박상식

    New piezoelectric and triboelectric materials for energy harvesting are being widely researched to reduce their processing cost and complexity and to improve … + READ MORE
    New piezoelectric and triboelectric materials for energy harvesting are being widely researched to reduce their processing cost and complexity and to improve their energy conversion efficiency. In this study, BaTiO3 films of various thickness were deposited on Ni foams by R.F. magnetron sputtering to study the piezoelectric and triboelectric properties of the porous spongy structure materials. Then piezoelectric nanogenerators (PENGs) were prepared with spongy structured BaTiO3 and PDMS composite. The output performance exhibited a positive dependence on the thickness of the BaTiO3 film, pushing load, and poling. The PENG output voltage and current were 4.4 V and 0.453 µA at an applied stress of 120 N when poled with a 300 kV/cm electric field. The electrical properties of the fabricated PENG were stable even after 5,000 cycles of durability testing. The triboelectric nanogenerators (TENGs) were fabricated using spongy structured BaTiO3 and various polymer films as dielectrics and operated in a vertical contact separation mode. The maximum peak to peak voltage and current of the composite film-based triboelectric nanogenerator were 63.2 V and 6 µA, respectively. This study offers new insights into the design and fabrication of high output nanogenerators using spongy structured materials. - COLLAPSE
    27 January 2024
  • Research Paper

    Evaluation of Microstructure and Mechanical Properties according to Cooling Method after Hot Forging of High Manganese Steel Flange

    고망간강 플랜지의 열간 단조 후 냉각방법에 따른 미세조직 및 기계적 특성 평가

    Minha Park, Gang Ho Lee, Byung Jun Kim, and Byoungkoo Kim

    박민하, 이강호, 김병준, 김병구

    High-Manganese (Mn) austenitic steel, with over 24 wt% Mn content, offers outstanding mechanical properties in cryogenic settings, making it a potential replacement … + READ MORE
    High-Manganese (Mn) austenitic steel, with over 24 wt% Mn content, offers outstanding mechanical properties in cryogenic settings, making it a potential replacement for existing cryogenic materials. This high manganese steel exhibits high strength, ductility, and wear resistance, making it promising for applications like LNG tanks, flanges, and valves. To operate in cryogenic environments, hot forging and heat treatment processes are vital, especially in flange production. The cooling rate during high-temperature cooling after hot forging plays a critical role in influencing the microstructure and mechanical properties of high manganese steel. The rate at which cooling occurs during this process influences the size of the grains and the distribution of manganese and consequently has an impact on mechanical properties. This study assessed the microstructure and mechanical properties based on different cooling rates during the hot forging of High-Mn steel flanges. Comparing air and water cooling after hot forging, followed by heat treatment, revealed notable differences in grain size. These differences directly impacted mechanical properties such as tensile strength, hardness, and Charpy impact property. Understanding these effects is crucial for optimizing the performance and reliability of High-Mn steel in cryogenic applications. - COLLAPSE
    27 January 2024
  • Research Paper

    Electrical and Optical Properties of Fluorine-Doped Tin Oxide Films Fabricated at Different Substrate Rotating Speeds during Ultrasonic Spray Pyrolysis Deposition

    초음파 분무 열분해 증착 중 기판 회전 속도에 따른 플루오린 도핑 된 주석산화물 막의 전기적 및 광학적 특성

    Ki-Won Lee, Myeong-Hun Jo, and Hyo-Jin Ahn

    이기원, 조명훈, 안효진

    Fluorine-doped tin oxide (FTO) has been used as a representative transparent conductive oxide (TCO) in various optoelectronic applications, including light emitting diodes, … + READ MORE
    Fluorine-doped tin oxide (FTO) has been used as a representative transparent conductive oxide (TCO) in various optoelectronic applications, including light emitting diodes, solar cells, photo-detectors, and electrochromic devices. The FTO plays an important role in providing electron transfer between active layers and external circuits while maintaining high transmittance in the devices. Herein, we report the effects of substrate rotation speed on the electrical and optical properties of FTO films during ultrasonic spray pyrolysis deposition (USPD). The substrate rotation speeds were adjusted to 2, 6, 10, and 14 rpm. As the substrate rotation speed increased from 2 to 14 rpm, the FTO films exhibited different film morphologies, including crystallite size, surface roughness, crystal texture, and film thickness. This FTO film engineering can be attributed to the variable nucleation and growth behaviors of FTO crystallites according to substrate rotation speeds during USPD. Among the FTO films with different substrate rotation speeds, the FTO film fabricated at 6 rpm showed the best optimized TCO characteristics when considering both electrical (sheet resistance of 13.73 Ω/□) and optical (average transmittance of 86.76 % at 400~700 nm) properties with a figure of merit (0.018 Ω-1). - COLLAPSE
    27 January 2024