Romisuhani Ahmad

Reviews on Clay Geopolymer Ceramic Using Powder Metallurgy Method

Inorganic polymers, commonly referred as geopolymers, are alumino-silicate materials which display superior physical and chemical properties with a diverse range of possible potential applications. Pure geopolymer matrix posses relatively low mechanical properties. The improvement on the properties can be made by focusing on the generation of ceramics from geopolymer. It’s a new world to explore yet with superior properties. The results showed the best curing temperature for clay geopolymers were at 60°C since it gained a fast initial setting. The hardened geopolymer clay will encounter physical metallurgy technique to be produced as geopolymer ceramic due to various high sintering temperature. It is proven that throughout heating the amorphous geopolymer transforms into crystalline phases with pure geopolymers demonstrates excessive shrinkage when sintered between 850 and 1000 °C.

Review on Development of Clay Based Geopolymer Ceramic Composites

Geopolymer results from the reaction of a source material that is rich in silica and alumina such as kaolin with alkaline activator solution. Geopolymers are inorganic aluminosilicate materials that possess relatively good mechanical properties and good thermal behavior but they exhibit failure behavior similar to brittle solids. This limitation may be readily overcome through the formation of ceramics of geopolymer and the addition of filler to improve strength and toughness. This paper review and summarize the current knowledge on geopolymer ceramic with addition of fine filler materials and the effect of filler content on the physical and mechanical characteristic of clay based geopolymer ceramic.

Realization of Wavelength-Time Modified Double Weight Codes Optical Code Division Multiple Access System

Explosive growth of bandwidth demand together with advance in latest communication services and emerging applications have inspired interest in optical code division multiple access (OCDMA). The work focuses on analysis and demonstration of two-dimensional (2-D) modified double weight (MDW) OCDMA wavelength-time. The 2-D MDW uses balance-detection for mitigating multiple access interference. The property of cross-correlation results in optimum phase induces intensity noise suppression (PIIN). The proposed code achieves high scalability; below 10-9 BER error floor the code cardinality reaches 254 simultaneous numbers of users which is double the 2-D PDC performance. The lowest effective power (Psr) for minimum optical transmission requirement for smallest number of users is achieved at-17.5dBm. The 2-D MDW OCDMA simulation model is developed to validate the realization of the code for BER and distance performance. The 2-D MDW OCDMA code successfully suppresses PIIN and mitigating MAI which result in high cardinality, reduce Psr and improved distance.

Effect of Ultra High Molecular Weight Polyethylene (UHMWPE) as Binder and Sintering Temperature in Kaolin Geopolymer Ceramics on Flexural Strength

This paper present the flexural strength of kaolin geopolymer ceramics with addition of ultra-high molecular weight polyethylene (UHMWPE) as a binder. The effect of varying UHMWPE loading and different sintering temperature on kaolin geopolymer ceramics were evaluated. Kaolin and alkaline activator were mixed with the solid-to-liquid ratio of 1.0. Alkaline activator was formed by mixing the 8 M NaOH solution with sodium silicate at a ratio of 0.24. Addition of UHMWPE to the kaolin geopolymer ceramics are fabricated with UHMWPE loadings of 2, 4, 6 and 8 (wt. %) by using powder metallurgy method. The samples were heated at different temperature started from 900 °C until 1200 °C and the strength were tested. It was found that the flexural strength for the kaolin geopolymer ceramics with addition of UHMWPE were higher and generally increased with the increasing of UHMWPE loading. Similar trend was observed for the effect of sintering temperature. The result revealed that the optimum flexural strength was obtained at UHMWPE loading of 8 wt. % and the samples heated at 1200 °C achieved the highest flexural strength (49.15 MPa).

Characterization and Microstructure of Kaolin-Based Ceramic Using Geopolymerization

Geopolymers can be transformed into ceramics upon sintering. This paper reports the effect of temperature on the physical, mechanical properties and characteristics of kaolin geopolymer ceramic. The nepheline ceramic was fabricated through geopolymerization. The geopolymer samples were exposed to temperature from 900 °C up to 1200 °C. Kaolin geopolymer undergo shrinkage upon temperature exposure. Unheated kaolin geopolymer appeared to be amorphous and crystalline nepheline was the major phase after sintered to high temperatures as depicted by XRD analysis. Microstructural analysis showed formation of denser structure as the temperature increased. The maximum flexural strength of 86 MPa is achieved at temperatures of 1200 °C.

Properties and Microstructural Characteristic of Kaolin Geopolymer Ceramics with Addition of Ultra High Molecular Weight Polyethylene

In this paper, the mechanical properties and microstructure of kaolin geopolymer ceramics with addition of Ultra High Molecular Weight Polyethylene were studied. Inorganic polymers based on alumina and silica polysialate units were synthesized at room temperature from kaolin and sodium silicate in a highly alkaline medium, followed by curing and drying at 80 °C. Alkaline activator was formed by mixing the 12 M NaOH solution with sodium silicate at a ratio of 0.24. Addition of Ultra High Molecular Weight Polyethylene to the kaolin geopolymer are fabricated with Ultra High Molecular Weight Polyethylene content of 2, 4, 6 and 8 (wt. %) by using powder metallurgy method. The samples were heated at 1200 °C and the strength and morphological were tested. It was found that the flexural strength for the kaolin geopolymer ceramics with addition of UHMWPE were improved and generally increased with the increasing of UHMWPE loading. The result revealed that the optimum flexural strength was obtained at UHMWPE loading of 4 wt. % (92.1 MPa) and the flexural strength started to decrease. Microstructural analysis showed the samples appeared to have more number of pores and connected of pores increased with the increasing of UHMWPE content.

The Effect of Solid-to-Liquid Ratio and Temperature on Mechanical Properties of Kaolin Geopolymer Ceramics

The effect of solid-to-liquid ratio and temperature on the mechanical properties of kaolin geopolymer ceramics are studied. Kaolin and alkaline activator were mixed with the solid-to-liquid ratio in the range of 0.8-1.2. Alkaline activator was formed by mixing the 12 M NaOH solution with sodium silicate at a ratio of 0.24. Kaolin geopolymer ceramic have been produced by using powder metallurgy (PM) technique. The samples were heated at different temperature started from 900 °C until 1200 °C and the strength were tested. The relative density and flexural strength of sintered sample range approximately 84%-95% and 20-90 MPa respectively. The result revealed that the optimum flexural strength was obtained at solid-to-liquid ratio of 1.0 and the samples heated at 1200 °C achieved the highest flexural strength (90 MPa).

Fabrication and Microstructure of Clay-Based Geopolymer Ceramic Using Powder Metallurgy Method

Geopolymers can be transforms into ceramics upon sintering. This paper reports the effect of temperature on the mechanical properties and microstructure of Na based kaolin geopolymer ceramic. The Na2O.Al2O3.4SiO2 was fabricated through powder metallurgy method. The geopolymers samples were exposed to temperature from 900 °C up to 1200 °C. The relative density, total porosity and flexural strength of sintered sample ranged approximately 84%-95%, 5.04%-15.73% and 20-70 MPa respectively. SEM analysis on as-sintered sample showed glassy phase while polished sample showed the pore structure and distribution. XRD results showed that nepheline appeared in all heated samples. Samples heated to 1200 °C achieved highest flexural strength and toughness of 70MPa due to the optimum density.

Fabrication of High Performance Geopolymer Ceramic Part I - Microstructural Properties

Geopolymer ceramic have been produced by the powder metallurgy (PM) technique. The samples were reacted by the alkaline activator to activate the geopolymerization process and crushed by using Mortar and Pestle to powderized the samples. Powder metallurgy technique was used and samples were heated at different temperature start from 700 °C until 1200°C and the strength were tested. The relative density and flexural strength of sintered sample ranged approximately 84%-95% and 20-100 MPa respectively. Microstructural properties was conducted by scanning electron microscopic (SEM) and the surface analysis by energy dispersive X-ray (EDX).

Correlation between Na2SiO3/NaOH and NaOH Molarity to Flexural Strength of Geopolymer Ceramic

Clay based geopolymer ceramic were produced through the geopolymerisation process by the alkali activation of kaolin with an activator solution which is mixture of sodium silicate and sodium hydroxide and undergoes heating at elevated temperature. The concentration of NaOH used in this study was in the range of 6 M-12 M. The ratio of kaolin to alkaline activator used is 1.0. Three different ratios of Na2SiO3/NaOH of 0.16, 0.24 and 0.32 were used to investigate the optimum flexural strength. The samples were cured at 80 °C for 24 hours and sintered at temperatures ranging from 900 °C-1200 °C. The optimum flexural strength of 86.833 MPa is obtained when the ratios of Na2SiO3/NaOH is 0.24 with the NaOH concentration of 12M at 1200 °C.