Materials Science Forum Vol. 819

Abstract: Many studies were carried out to investigate the ability of titanium alloys for dental implant. Surface treatment is one of the famous methods to increase the titanium surface properties. The purpose of this paper is to investigate the effects of acid etching on the surface topography and roughness of titanium alloys (Ti6Al4V ASTM 1472-99). Acid etchings were carried out by using different type of acids with same time exposures. All etched surface were characterized by using an X-ray diffraction (XRD), a scanning electron microscope (SEM) and a roughness tester. Acid etched and pure surface were comparatively analysed. Results obtained show that the type of acids influenced the surface topography as well as roughness properties. The microstructure of the surface is highly modified after acid etching. Further we can confirm that, the experimental etched titanium alloys had features of a roughened surface with micro-roughness. In general, the experimental surface (0.137 μm – 3.986 μm) was significantly rougher than control surface (0.124 μm).

Abstract: Mesoporous carbonated hydroxypatite (CHA) is a promising drug delivery agent for disease treatment and could be a carrier for different types of drugs and antibiotics. It is still a challenge to introduce pores to carry drugs within the mesoporous CHA and obtain high surface area nanoparticles. This study investigates the effect of different types of nonionic surfactant and carbonate concentration on the pore characteristic of mesoporous CHA. Mesoporous CHA is synthesised through the coprecipitation technique using nonionic surfactants as pore templates i.e., P123 and F127 with different carbonate concentration. The axial view of transmission electron microscopy (TEM) images shows the pores formed within the particles are distributed randomly, while the parallel view demonstrates that nanopore channels are developed within the CHA particles. Nitrogen adsorption analysis provides the surface area and Pore Size Distribution (PSD) of the nanoparticles. The PSD shows that CHA synthesis with P123 and F127 has similar pore size, around 28.9 nm, but different surface area. The results confirm the different types of surfactant templates has a positive effect on the pore characteristic, while carbonate precursor concentration does not significantly change surface area and pore size.

Abstract: The fabrication of porous poly (ethylene glycol) (PEG)-based hydrogel scaffolds via epoxy-amine crosslinked polymerization was conducted in this research works. PEG was chosen as the main component of the hydrogel scaffolds due to their unique characteristic including high hydrophilicity, biocompatibility and low toxicity properties. The effects of different solvents ((water, dimethylsulfoxide (DMSO), triethylene glycol dimethyl ether (TGDME), etc) toward physical and mechanical properties of fabricated PEG-based hydrogel scaffolds were investigated to identify the suitable solvent for fabrication of porous hydrogel scaffolds. From the results obtained, DMSO was selected as the solvent because the produced hydrogels scaffolds possessed the optimum physical properties as compared to other solvents. In tissue engineering field, porosity of scaffolds play key role for cell attachment, grow and proliferation consequently help in regeneration of new tissues. Therefore, in this study the macroporous hydrogel scaffolds were produced via introduction of fused salt templates in the range sizes of 100–300 μm (small) and 300–600 μm (large) in the fabrication process. Improved interconnectivity of pores was achieved and pores sizes obtained were according to the size of salt particles utilized in the template. Modification of the scaffolds pore morphology resulted in a reduction in the mechanical properties as we expected.

Abstract: Research and development on the biomaterials are increasing due to the demand for materials that can bond to the living bones and by any chance can avoid second surgery procedure. Good bonding between bones and biomaterials or artificial implant can avoid loosening that due to the friction and wear. Currently, magnesium alloys are being actively researched because of their ability to serve as structural support in short term and can be absorbed in the body after healing process is completed. The addition of bioactive components such as hydroxyapatite and bioglass into magnesium is made to improve the bioactivity behavior of magnesium alloys. This paper summarizes the past and current studies of magnesium alloys in regards of in vitro bioactivity behavior, biomineralization and apatite formation mechanism.

Abstract: The influence of alginate concentration on the diametral tensile strength (DTS) of hydroxyapatite (HAp) block was investigated. Alginate solution with concentration of 1%, 3% and 5% was prepared through neutral extraction from cultivated sargassum polycystum brown seaweed obtained from Semporna, Sabah, Malaysia. Commercially available HAp powder was pressed uniaxially at 3 MPa to obtain the HAp block. The HAp block was then sintered at 900°C. The sintered HAp block was then immersed in alginate solution under vacuum condition for 24 hours. DTS value of the HAp block decreases with increasing alginate concentration. Porosity measurement increases with the increase in alginate concentration used. The decrease in the DTSvalue with increasing alginate concentration is due to the higher viscosity at higher alginate concentration and thus limited the amount of alginate being penetrate into the HAp block.

Abstract: The potential converting the end-life product into a renewable source and replaced the conventional material found in iron and steelmaking production next tackled the world’s most problematic waste stream. Generally, integrating the waste material becomes wealth only available to certain wastes industries due to high temperature application. Recycling waste materials were introduced in order to control slag foaming in EAF steelmaking. The present paper reviews about slag foaming behaviour focused on slag droplet volume (V_t/V₀ ratio), their transformation and morphology during carbon/slag interaction using sessile-drop technique at 1550°C on polymeric (HDPE), agricultural waste (palm shell), rubber tyres and metallurgical coke as the potential carbonaceous materials in EAF steelmaking. These results indicate that partial replacement of conventional materials with recycled waste materials is efficient due to improved interactions with EAF slag.

Abstract: The rolled homogeneous armour (RHA) plate is commonly used for armoured vehicle skin. Preliminary predictions of the deflections from RHA plate subjected to blast loading is important for establishing guidelines before it is used in vehicle skin. The goal of this work is a reliable technique for predicting the RHA plate response subjected to blast loading, and the empirical result performed by other researchers will be taken as a reference. Based on selected references, a small number of assumptions lead to the developed Single Degree of Freedom (SDOF) idealised models. This paper provides an analytical prediction for the RHA plate response using SDOF in one dimension (1D) approach. The analytical capability was subsequently verified using the non-linear fluid structure interaction (FSI) numerical simulation and the AUTODYN computer code. The midpoint deflections of the RHA plate were taken as the figure of merit. Based on the small error percentage and the support of strong analytical arguments, the second order SDOF analytical approach and numerical simulation using the AUTODYN computer code can be employed as a method of analysis.

Abstract: The reaction of limestone in the slaking process has been studied under different conditions of parameters such as calcination times, soaking times and particle sizes. The reactivity of quicklime was determined by recording temperature rise and the rate of temperature rise during the slaking process. The obtained ‘milk of lime’ is characterized using instrumental measurements such as X-ray fluorescence (XRF) to identify the chemical composition that exists in the sample. In this paper, the quicklime used during slaking test indicates the differential of temperature pattern which influences by quicklime particle sizes, calcination temperatures and soaking times. Results indicate that the optimum and efficient distribution of heat transfer and thermal decomposition onto quicklime can be obtained by calcining at 1100 °C with 60 minutes of soaking time samples which produced a highly porous structure towards higher reactivity of quicklime.

Abstract: This research presents the findings of experimental works in terms of mechanical properties and crack profile of cement composites containing quarry dust at different percentages as a partial sand replacement. The compositions of quarry dust were varied from 10 to 20 wt. % and were mixed into five different ratios. It was found that 0.45 water cement ratio was suitable to mix all proportions and values of slump were observed have been increased with the increasing percentage of quarry dust in cement composites. The compressive strength tests were carried out and the results showed that the compressive strength decreased at each 2.5 percent interval of quarry dust at 7 and 28 days of curing. However, the strength developments of cement composites were increased corresponding to the ages of curing. The crack profiles of cement composites have been analyzed to investigate the strength developments of the cement composites. According to the results, the cracks in the specimens were in shearing pattern at 10 and 12.5 wt. % of quarry dust in cement composites. Meanwhile, as the contents of quarry dust at 15, 17.5 and 20 wt. %, the specimens failed in shearing and splitting patterns. According to the findings of compressive strength and crack profile, the contents of quarry dust as a partial sand replacement is 12.5 wt. % were more suitable to be utilized in cement composite

Abstract: Increasing interest of attachment gold nanoparticles (AuNPs) on titanium oxide (TiO₂) nanotubes has been devoted to give tremendous properties suitable for catalysis application. Nevertheless, achieving precise control of attachment AuNPs on the TiO₂ nanotubes substrate by conventional methods such as thermal evaporation and conservative heating are far from satisfactory. Herein, in this work a new approach has been developed to synthesize controlled and uniformed attachment of AuNPs onto electrochemically-anodized TiO₂ nanotubes by deposition-precipitation method. The structural and elemental characterizations of the supported AuNPs are carried out by means of field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDX) analysis. The FESEM image showed the anodized TiO₂ nanotube with good morphological structure is successfully fabricated at a voltage of 20 V and in a mixture electrolyte of ethylene glycol containing 0.5 wt% ammonium fluoride solutions with an average nanotubes diameter of 87 nm. Meanwhile, the attachment of AuNPs on the fabricated TiO₂ nanotubes has been effectively achieved for both calcined and uncalcined samples. The EDX analysis has confirmed the deposition of AuNPs over the TiO₂ nanotubes. The results showed that we had succeeded in synthesizing the AuNPs supported on the anodized TiO₂ nanotubes, which provide superior metal-metal oxide synthetic devices for diverse applications.