Papers by Keyword: Ceramic

Abstract: The 5 mol% Fe-doped BaTiO₃ ceramic has been synthesized by using solid-state method. The sample was characterized by X-ray diffraction (XRD) and Impedance spectroscopy. It is interesting to note that the sample can developed a phase transformation between 1000 °C to 1350 °C. The XRD results showed that sample exhibited cubic structure when heated at 1000 °C and developed oxygen non-stoichiometry when it was heated at 1350 °C for 8 hours. It was confirmed by the ceramic color changes. The dielectric properties of the sample is relatively low which is due to the oxygen non-stoichiometry effect and gives the dielectric constant, ε_r value around 150 at 30 °C with frequency 1 kHz. The capacitance value of this sample lies within 10^-8 to 10^-10 which represents that the electrical properties of the sample has shown bulk and grain boundary response. There are pores that can be observed from the SEM images indicates the porosity of the sample which is in a good agreement with the low dielectric constant value. Moreover, the grains are composed of rectangular orientations, hexagonal shapes and inhomogeneous microstructures that might represent the coexistence of tetragonal and hexagonal phase of the sample.

Abstract: The BaTi_0.88Zr_0.12O₃ ceramic has been synthesized by using a conventional solid-state reaction method and sintered at 1450 °C in air for 3 hours. The structural and dielectric properties of the sample were investigated. It was found that the sample exhibited tetragonal structure with space group P4mm. The maximum dielectric constant, ε_r value was obtained at T_c (70 °C) about 2800 measured at 1 kHz. The dielectric peak was broad which might be due to the pinching effect. However, maximum ε_r value was quite low may be attributed by the T_c and other phase transition point might be not fully coalescence. Another phase transition temperature was vaguely observed around 30 °C to 40 °C. The dielectric properties of the sample were dominated by the grain effect with capacitance values lie within range of 10^-10 to 10^-9. The SEM images shows that the average grain size of the sample was quite small about 2.9087 μm. It might be due to the contribution of Zr⁴⁺ with lower grain growth rate.

Abstract: The dielectric properties and crystal structure of Ba_0.85Sr_0.15TiO₃ and Ba_0.85Sr_0.15Ti_0.92Zr_0.08O₃ ceramics were studied. The samples were synthesized by using solid-state method. The results show that the samples were single phase. The Ba_0.85Sr_0.15TiO₃ exhibited tetragonal structure (space group P4mm), while with addition of 8 mol% Zr into Ba_0.85Sr_0.15TiO₃ it shows that the sample exhibited orthorhombic structure (space group Amm2). The dielectric constant value increased from 1094 for pure, up to 4211 for Ba_0.85Sr_0.15Ti_0.92Zr_0.08O₃ ceramic at T_c measured at 1 kHz. The T_c decreased from 80 °C down to 60 °C as 8 mol% Zr ions doped into Ba_0.85Sr_0.15TiO₃ composition. The Ba_0.85Sr_0.15Ti_0.92Zr_0.08O₃ ceramic exhibited lower dielectric loss, tan δ about 0.006 compared to Ba_0.85Sr_0.15TiO₃ ceramic (tan δ = 0.009) when measured at 110 °C with frequency 1 kHz. The slope at low frequency region in capacitance vs frequency plot for both samples attributed by the grain boundary effect, whereas the high frequency plateau associated with the bulk response. The impedance spectroscopy analysis results show that both samples are dominated by the bulk response when an incomplete semicircle arc was observed in Zʺ vs Zʹ plot.

Abstract: The BaTi_0.905Sn_0.095O₃ ceramic has been synthesized by using a solid-state method and sintered at 1450 °C in air for 3 hours. The doping effect of 9.5 mol% Sn into BaTiO₃ ceramic towards its crystal structure, dielectric properties and microstructure were investigated. The X-ray diffraction (XRD) analysis shows that the sample exhibited tetragonal structure with space group p4mm. The dielectric constant, ε_r measurement revealed that the sample reached the maximum ε_r value about 4393 when measured at T_c around 45 °C with frequency 1 kHz. The dielectric loss value was considerably low about below than 0.3 for the temperature range from 30 °C to 150 °C measured at 1 kHz. The capacitance value range lies between 10^-9 and 10^-10 indicates the bulk effect has dominated the electrical properties of the sample. It shows a good correlation with the microstructure results where the grains were well developed and homogenously distributed.

Abstract: The manufacture of ceramic brick goes through the stages of raw material extraction, clay homogenization, material conformation, drying and firing. Drying is the phase that needs greater care, as it involves removing part of the moisture from the brick, in order to preserve its quality after process. This work aims to predict heat and mass transfer in the drying of ceramic bricks in oven using computational fluid dynamics. Considering the constant thermophysical properties, a transient three-dimensional mathematical model was used to predict mass and energy transfer between the material and air during the process. Drying simulations at temperature of 100°C were performed with the air flow in the frontal direction to the ceramic brick holes and the results were compared with those obtained for the air flow in the perpendicular direction to the brick holes reported in the literature. It was found that the position of the brick in relation to the direction of air flow inside the oven affected directly the drying and heating kinetics, and the distribution of temperature and moisture content inside the brick. The positioning of the holes in the brick parallel to the direction of the air flow resulted in reduction at the drying time and, consequently, in energy savings in the process, more uniform drying, and improvement in the product quality.

Abstract: The ZTA-TiO₂-Cr₂O₃ ceramic cutting tool is a new cutting tool that possesses good hardness and fracture toughness. Yet, the performance of the ZTA-TiO₂-Cr₂O₃ cutting tool is still unknown and needs further study. In this research, the comparison of the ZTA-TiO₂-Cr₂O₃ and Kennametal ceramic cutting tool is investigated. The turning process by using ZTA-TiO₂-Cr₂O₃ and Kennametal commercial ceramic cutting tools is performed on the Bridgeport ROMI PowerPath CNC lathe machine. The parameters utilized are spindle speed in the range of 907 to 1543 rpm, feed rate from 0.08 to 0.22 mm/rev, and depth of cut of 0.2 mm. Analysis of the flank wear and crater wear were performed by using an optical microscope (NIKON MM-4001L), while the chipping area was observed by scanning electron microscopy, SEM (JEOL JSM-IT100). The surface roughness of the machined surface is measured via portable surface roughness (Mahr MarSurf M3000C). The comparison between the cutting tool produced in this research and the commercial cutting tool shows that the wear performance of the ZTA-TiO₂-Cr₂O₃ ceramic cutting tool is lower than the Kennametal commercial ceramic cutting tool. Even though this newly fabricated cutting tool is far behind compared to the commercial cutting tool, it shows some promising aspects such as the ability to cut at a higher speed.

Abstract: The aim of study is to produce durable structural concrete by using waste ceramics with specified type (white clay ceramics) as coarse aggregates in concrete. Mechanical properties were studied, the study also show good resistance to fire resistance for concrete contains ceramics as coarse aggregates compared with normal aggregates concrete, good mechanical properties such as compressive, tensile, and flexural strength. Results of study gave 17.5% increment in compressive strength by using 100% replacement of waste ceramic, flexural strength increased with 27.8% increment. Study also show less reduction in strength due to fire resistance by using waste ceramics compared to ordinary concrete, and also more durable concrete for salty water effects by using ceramic.

Abstract: Vat photopolymerization is one of additive manufacturing and also known as photo-curable three-dimensional printing technology. It uses light energy with the proper wavelength to expose on the liquid photo-curable resin inducing the photopolymerization process and resulting in solidification layer-by-layer. The building method is classified into two ways: free-surface and constrained-surface. The advantage and disadvantage of both methods are described and analysed according to the different material property and requirement. The basic composition for photo-curable resin consists of photo-initiator and monomer. Adding powder into photo-curable resin makes the photo-curable slurry. Literatures report that high density powder such as zirconia oxide or Inconel 718 is suitable for free-surface building method because of poor suspension. However, the volume percentage in the slurry is less than 50% causing the higher shrinkage ratio and inaccuracy after sintering process. The coupling agent may increase the suspension of powder in slurry but experimental result shows that it still cannot improve the success rate in the constrained-surface building method. Therefore, this study proposes a combination method to overcome the difficulty of making high density ceramic or metal part. In addition, the sintering process is a key factor to obtain the high dense part with no crack occurrence and desirable microstructure. The optimized sintering parameters for zirconia oxide and Inconel 718 are also introduced.

Abstract: This paper investigated the performance of ZTA cutting tool with the addition of different particle size of MgO additive. Therefore, the objective of this research is to compare the effects of machining parameters on tool wears of ZTA cutting tools added with micro and nanoparticle of MgO. The experiments were conducted using BridgePort-Romi Powerpath CNC machine using a tool holder Sandvik Coromant (CoroTurn CCLNR 164D-4) to hold the cutting tools properly. The parameters are set up as cutting speeds used between range 354 to 472 m/min, feed rate from 0.1 to 0.5 mm/rev with a constant depth of cut of 0.2 mm. Three types of wear were analyzed which are flank wear, crater wear and tool chipping. Flank wear and crater wear images captured using measuring microscope (NIKON MM-400/L) and the crater wear areas are analyzed using MatLab programming software. Tool chipping is observed via SEM (JEOL JSM-5600). The experimental result shows that flank wear and crater wear increase when cutting speed and feed rate increase. ZMN cutting tool shows lower value of flank wear at 0.143 mm and 3.741 mm² for crater wear than ZMM, 0.321 mm and 3.808 mm² respectively. On the contrary, cutting speed did not affect the tool chipping severely as feed rate. Moreover, ZMN also shows that the tool breakage occurred severely than ZMM due to the high load on the tool nose.

Abstract: The study has been done in membrane production from the ratio of clay, zeolite and activated carbon. The goal of this study is to make membrane from clay, zeolite and activated carbon with micro particle size using Planetary Ball Milling Fritsch Pulverisette. The comparison of clay, zeolite and activated carbon is 80% : 10% : 10%, 70% : 20% : 10%, 60% : 30% : 10%, 50% : 40% : 10% with temperature combustion 600 °C, 700 °C dan 800 °C. Activated zeolite done with using HCl 2 M and then heated at 150 °C for 3 hours. Size particle from zeolite is 140 mesh with using Planetary Ball Milling Fritsch Pulverisette to reduce size of zeolite become 140 mesh with a rotation speed of 350 rpm for 6 hours. The result of this study shows that the highest flukes membrane found in clay, zeolit and activated membrane at 50%: 40%: 10% with temperature combustion at 800 °C around 4,859 L/jam.m². The compressive strength on clay: zeolite: activated carbon ( 80%: 10%: 10%) with temperature burning at 600 °C around 39,6977 kg/cm². Characterization testing using Scanning Electron Microscopy (SEM) on ceramic membranes with clay composition: zeolite: activated carbon = 50%: 40%: 10% at a combustion temperature of 600 °C obtained by membrane pore size of 2,699 μm. Adsorption with the optimum time obtained at 1 hour with a concentration of 0,2333 ppm. The highest effect of membrane composition on cation exchange capacity (CEC) is in the composition of 50%: 40%: 10% with a combustion temperature of 600 °C which is equal to 1.1 mgrek/g..