Norkhairunnisa Mazlan

Factors Affecting the Porosity and Mechanical Properties of Porous Ceramic Composite Materials

In recent years, there has been an increasing interest in the study of porous ceramic composite materials. There are many products made of porous ceramic, such as membranes, catalytic substrates, filters, and others. This is due to their excellent properties in terms of high temperature stability, high permeability, excellent catalytic activity, and low bulk density. The purpose of this article is to review in detail the factors affecting the porosity of ceramic material, such as pore forming agents, the mechanical properties, and methods available to strengthen the material, such as sintering temperature, ceramic additives, and metal particle as additives and coating. Machining is also a concern regarding products made of ceramic materials since it is brittle in nature. Parameters optimized to improve machinability for ease of machining process were also discussed to address this concern.

Investigations on Composite Flexural Behaviour with Inclusion of CNT Enhanced Silica Aerogel in Epoxy Nanocomposites

Growing of carbon nanotubes (CNT) on the surface of highly porous silica aerogel offers a means to tailor the mechanical properties between fiber and matrix interface of a composite. The growth of CNT on the silica aerogel surface was done using chemical vapour deposition (CVD) technique. In this study, the morphology of the produced CNT was investigated by Scanning Electron Microscope (SEM) for confirmation of CNT existence. The composite were then prepared by shear mixing technique. Flexural strength of the CNT-SilAe/Epoxy nanocomposite were assessed as a function of CNT-SilAe concentration and dispersion in epoxy matrix. The flexural modulus and strength of epoxy composite increased significantly with inclusion of CNT-SilAe. The optimum loading of CNT-SilAe in epoxy composites was attained at 2 wt%, where the improvement in flexural strength and modulus were 8% and 11%, respectively.

Elastomeric Nanocomposite Based on Exfoliated Graphene Oxide and Its Characteristics without Vulcanization

Rubber nanocomposites have emerged as one of the advanced materials in recent years. The aim of this work was to homogeneously disperse graphene oxide (GO) sheets into Nitrile Butadiene Rubber (NBR) and investigate the characteristics of GO/NBR nanocomposite without vulcanization. A suitable solvent was found to dissolve dry NBR while GO was exfoliated completely in an aqueous base solution using sonication. GO was dispersed into NBR at different loadings by solution mixing to produce unvulcanized GO/NBR nanocomposites. Scanning Electron Microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), and X-Ray Diffraction (XRD) were used to characterize the samples. Furthermore, mechanical and electrical properties of unvulcanized GO/NBR nanocomposites were carried out to determine the influence of GO on the NBR properties. The results showed that the modulus of GO/NBR nanocomposite at 1 wt% of GO was enhanced by about 238% compared with unfilled NBR. These results provide insight into the properties of unvulcanized GO/NBR nanocomposite for application as coatings or adhesives.

Fire Retardant Performance of Rice Husk Ash-Based Geopolymer Coated Mild Steel - A Factorial Design and Microstructure Analysis

Higher content of silica in geopolymer coating resulted in better thermal properties. Since rice husk ash (RHA) has the highest silica content compared to other aluminosilicate sources available, it offers the best potential to be an alternative silica source in producing geopolymer coating binder. In this study, five factors including ratio of alkaline activator (AA) (A), ratio of RHA/AA (B), curing temperature (C), curing time (D) and concentration of NaOH (E) were analyzed using statistical analysis to identify the significant factors that mostly influence fire retardant performance of RHA-based geopolymer coating. The fire retardant tests were conducted and results recorded included (i) time taken to reach 300°C and (ii) temperature at equilibrium. Sample S7 (coating composition of A=5.5, B=0.3, C=50°C, D=7days, E=8M) which produced the best fire retardant performance was selected for further detailed investigation using thermogravimetry analysis (TGA) and scanning electron microscopy (SEM). It was found that the back temperature of mild steel plate of sample S7 reached 300°C after 17 minutes and achieved an equilibrium state at 398°C. SEM micrographs showed the presence of needle-like structures formed after fire test might be the reason for the best fire performance of sample S7.