Mohamad Hasmaliza

Characterization and Phase Evolution of Cordierite Based Glass Synthesis from Pure Oxide and Minerals

α Cordierite is very important phase in MgO-Al2O3-SiO2 system because of their very outstanding thermal, chemical and electrical properties. In this presents study non-stoichiometry cordierite (MgO:Al2O3:SiO2 = 3:1.5:5) using 2 different initial raw materials ( (i)mixture of pure oxide, and ii) mainly mixture of minerals) were fabricated and compared in terms of phase transformation and physical properties. Cordierite was prepared by glass method at low melting temperature (1350oC). Low melting temperature has resulted in partly crystalline glass which has possesses higher hardness, required longer milling time and result in contamination from grinding media. However, α-cordierite has successfully crystallized and fully densified at 850oC/2h. Activation energy for densification was investigated from thermal expansion coefficient (TCE) results. Other properties that were discussed included thermal properties using DTA/TGA.

Porous Cordierite Synthesized Using Corn Starch

Cordierite (2MgO.2Al2O3.5SiO2) is an advanced ceramic which is popular for its high melting temperature and high resistance to thermal, chemical and corrosion and also low dielectric constant. The use of various structure of cordierite especially porous structure became more popular where its properties can be tailored by controlling the open and closed porosity, cell size distribution and cell morphology. In this study, porous cordierite was synthesized using sol gel method with addition of corn starch (5wt%, 10 wt%, 15 wt% and 20 wt %) as pore forming agent. Characterizations have done using scanning electron microscope (SEM) show that the corn starch used is polyhedral shape with pore size between 6-7 μm. Whereas SEM analysis on sintered sample shows that the porosity obtained ranging from 13 to 46 % with interconnected pores.

The Effects of Cr2O3 Addition on Fracture Toughness and Phases of ZTA Ceramic Composite

Fracture toughness and phases of ceramic composites produced from alumina, yttria stabilized zirconia and chromia oxide system was investigated. The Cr2O3 weight percent was varied from 0 wt% to 1.0 wt%. Each batch of composition was mixed, uniaxially pressed 13mm diameter and sintered at 1600 C for 4 h in pressureless conditions. Studies on on their mechanical and physical properties such as Vickers hardness and fracture toughness were carried out. Results show that an addition of 0.6 wt% of Cr2O3 produces the best mechanical properties. Results of the highest fracture toughness is 4.73 MPa.m1/2,

Synthesis of MWCNT-Alumina Hybrid as Composite Reinforcement Using Nickel Catalyst

This work focuses on synthesis of MWCNT-alumina hybrid compound via methane decomposition process using nickel catalyst. The catalysts prepared through in situ process by using nickel salt and aluminium powder which then calcined at 900oC followed by methane decomposition process to grow MWCNT on alumina surface. The Scanning Electron Microscopy (SEM) and High Resolution Transmission Electron Microscopy (HRTEM) images confirmed the formation of MWCNT with homogenous dispersion on alumina particles.

Effect of Cao from Different Sources on the Nanostructured Cordierite

Cordierite was synthesized via glass-route using mineral and pure oxide material. Kaolin, talc, dolomite, magnesia, alumina, silica, and calcium oxide were mixed and melted. CaO from mineral and pure oxide was added in order to investigate the properties of each material in cordierite system. Sample was characterized using X-ray diffraction (XRD) analysis and dilatometer testing. The result showed that when 5wt% CaO from mineral (C5 Min) was added and sintered at 900°C, α-cordierite exist as major phase and anorthite as a minor phase. While for a sample consists of 5wt% CaO from pure oxide (C5 Ox), α-cordierite was present as major phases, µ-cordierite and anorthite as minor phases. Crystallite sizes of each material were in nanorange and crystallite size of C5 Ox was less than C5 Min.

Production of Porous Cordierite through Sol-Gel Polymeric Sponge Method

Cordierite (2MgO.2Al2O3.5SiO2) is widely used in high temperature applications due to its high melting temperature and high resistance to thermal shock, chemical and corrosion. In this study, porous cordierite was synthesized using sol-gel method followed by replication of polymeric sponge method. Three different sintering temperatures were studied (1200°C, 1300°C and 1400°C to determine the crucial temperatures meant for pure cordierite phase. The effect of different temperature on the pore size, density and porosity were also studied. Produced porous cordierite was then analyzed using X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). XRD results showed that pure cordierite phase was obtained at 1300°C. SEM micrograph shows that with increasing sintering temperature, the pore size decreased and sample sintered at 1300°C has pore size ranging from 61-126μm.

Effects of the polyvinyl alcohol (PVA) on the synthesis of alumina fibers through electrospinning technique

Alumina fiber products have high modulus and strength that are resistant toward the attacks of molten metals and non-oxide materials up to 1000°C. Fibers also have low thermal conductivity and high melting point. In this work, alumina fibers were synthesized by sol-gel electrospinning technique (e-spinning). The sol was prepared by mixing aluminum nitrate nonahydrate (ALN) and aluminum isopropoxide at 1:3 molar ratios. The precursor sol was stirred vigorously for 24 hours until ALP completely dissolved. After stirring, the precursor sol with PVA and without PVA was evaporating to obtain the suitable viscosity to spin. The rheology and viscosity were checked by viscometer. At the appropriate viscosity range about 0.2 to 7 Poise, the sol was then spinning into fibers using electrospinning machine. The green fibers were then dried at room temperature then calcined at 1200°C. The fibers produced were characterized using X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscope (FESEM). The XRD analysis had shown the α-alumina was formed at 1200 °C and SEM micrograph shows the formation of fibers with PVA addition.

Granite waste as a raw material in ceramic body formulations

The escalating interest of researchers to use industrial waste materials in the manufacture of ceramic products is growing. This work is aimed at studying the properties of granite waste (GW) upon incorporation in ceramic bodies. Initially, the GW was characterized in terms of chemical and mineralogical compositions. Then, the GW was added (in the range 40-60 wt.%) to a ball clay. Firing was carried out at 1100°C to1200°C and then the properties of the fired specimens were determined. The results showed that specimens with GW 50 wt.% fired at 1150°C exhibited the best properties, i.e. minimum water absorption of <0.36%, the best bulk density (2.48 g/cm3) and strength (21.34 MPa). This showed that GW can act as a fluxing agent and reduces the firing temperature of the ceramic body with additional advantages in terms of cost and reuse of waste materials.

Effect of the Sponge Used as the Template for the Production of Porous Cordierite

Cordierite (2MgO.2Al2O3.5SiO2) is widely used in high temperature applications due to its high melting temperature and high resistance to thermal, chemical and corrosion shock. The use of various structure of cordierite especially porous structure became more popular where its properties can be tailored by controlling the open and closed porosity, cell size distribution and cell morphology. In this study, porous cordierite was synthesized using sol-gel method followed by replication of polymeric sponge method using three different types of polymeric sponge (Type A, B and C). Immersed sponge were then sintered at 1300°C to determine better sponge types to produce porous cordierite. Sponge was characterized using FTIR and porous sample produced were characterized using Scanning Electron Microscope (SEM) and density and porosity testing.

Phase Formation of α-Cordierite Using Different Sintering Profile

ndialite or α-cordierite was synthesized by glass crystallization method. Effect of different sintering profile; single stage sintering (1s) and two stages sintering (2s) on phase formation was determined via x-ray diffraction (XRD) analysis using rietvield method of HighScore Plus software. It has been found that 1s produce 85 % of α-cordierite with 15 % anorthite as secondary phase while, α-cordierite appeared about 68.6 % with 24.3 % anorthite and 7.1 % forsterite as secondary phase using 2s sintering profile.