Advanced Materials Research Vol. 845

Abstract: Novel ladderlike polysilsesquioxanes containing polypropylene moieties (LPS-PP) were synthesized from LPS having chloromethylphenyl groups (LPS) and polypropylene having hydroxyl groups (PP-OH). LPS-PP was characterized by FT-IR, DSC, SEM, EDX, and TGA. The obtained LPS-PP shows no melting temperature due to the disappearance of melting temperature of PP, indicating the rigidity of Si-O-Si backbone in ladderlike LPS. The char yield of LPS-PP is higher than that of PP-OH because of the silica parts of LPS. This new LPS-PP can be an interesting candidate to fabricate hybrid materials using interactions or compatibility between PP moieties of LPS and various organic polymers.

Abstract: The well condition asymptotic waveform evaluation (WCAWE) is presented to solve heat conduction problem with different boundary conditions. The method introduced by R. D. Slone and his colleague to solve electromagnetic problems in the frequency domain. Specially, the novelty of this paper is: This is the first time WCAWE method is presented for thermal analysis, the method is presented for time-dependent problems. The general formulation procedure is given and various examples are solved to illustrate the capabilities of the proposed scheme. The results obtain in this work by using WCAWE method showed that, the WCAWE method successfully able to approximate the initial delay. Therefore, WCAWE method is able to remove the limitation of time domain AWE

Abstract: Fixation with cannulated screw was widely accepted for management of femoral neck fracture. However, the angle of placement cannulated screw for management of femoral neck fracture still controversial. The present study aims to investigate the mechanical behavior of the cannulated screws with two different angles of placements which are 135^o and 150^o in inverted triangular configuration for management of femoral neck fracture via finite element method. Therefore, the 3D model of a proximal femur consist of femoral neck fracture was constructed from CT data images using medical image processing software. The von Mises stress distributions on the cannulated screws were compared between each screw angle placement. The result showed that the cannulated screws in inverted triangle with 135^o of placement angle have better stress distributions than 150^o placement angle.

Abstract: The growth of intermetallic phases in Al/Cu bilayers thin film having 2/3 layer thickness ratios were characterized by X-ray powder diffraction (XRD), energy dispersive X-ray (EDX) and transmission electron microscopy (TEM). In annealing temperature of 200 °C, the growth is controlled by Cu diffusion which resulted to formation of θ-Al₂Cu, η-AlCu, ζ-Al₃Cu₄ and γ-Al₄Cu₉ phase.

Abstract: This paper encompasses the work from numerical model by investigating the compression response of CFRP composite cylinder shells. The aim of this paper is to improve the reliability of NASA SP-8007 design guideline. The cylinder geometrical imperfections were tested through numerical modelling and validate with the experiment results. Good results comparison has been obtained through the work with small amount of errors. The cylinder shell load carrying capacity has been improved by average of 56% through imperfection study. This work builds confidence in the future use of non-linear finite element for the design of composite cylinder subjected to axial compression load.

Abstract: The SAE1070 steel grade, used especially in the automotive industry, has strict specifications and some of them are limits to oxidation and decarburization, which implies carbon loss through a variety of diffusion mechanisms. Temperature, atmospheric oxygen potential, carbon chemical potential gradient and time of high temperature exposure are some of parameters, that influence the extent of decarburization. Oxidation influences decarburization losses, in the metal/oxide interface, and as a result of this interface moves into the sample. During the reheating of billets for hot rolling, measures to contain oxidation to the minimum becomes a priority. In this work, the extent of oxidation and decarburization has been studied in the laboratory under industrial conditions as industrial scale experiments are expensive and not very practical. Mathematical modeling based on the results of laboratory experiments becomes attractive as this can be applied to industrial conditions. Isothermal tests for the evaluation of oxidation and decarburization were conducted in an electric furnace in the temperature range 600°C - 1100°C and time ranging from 2 hours to 48 hours. Decarburization and oxidation were measured by techniques such as weight change ue to removal of scale, micro-hardness testing and optical microscopy. Based on the methodology ,an algorithm has been developed for assessment of oxidation and decarburization occurring in the industrial reheating of billets With minor adjustments, it is shown that, the model can be satisfactorily applied with reasonable accuracy. Keywords: Decarburization, Oxidation , Steel billets , Modeling

Abstract: Fibers from the culms of Bambusa arundinacea and Dendrocalamus asper were extracted mechanically and chemically treated using alkaline solution. Tensile and thermal properties of both bamboo fibers were examined. Tensile test on the bamboo fibers showed that Bambusa arundinacea fibers have higher strength and stiffness yet lower elongation than Dendrocalamus asper fibers. When the fibers were chemically treated, similar trend on tensile properties was observed but at lower magnitude compared to those shown by untreated fibers. Further characterization revealed that Bambusa arundinacea fibers are of higher fiber diameter and higher cellulose content compared to Dendrocalamus asper fibers. Thermogravimetric analysis showed that both fibers with same treatment have similar thermal stability, with chemically treated fibers are of higher thermal stability than untreated ones. The chemical treatment removed the lignin from the fiber structure, and affected tensile and thermal properties of both bamboos fibers.

Abstract: In this paper, direct current plasma magnetron sputter deposition technique was employed to deposit zinc oxide (ZnO) films on glass substrates. The magnetron sputtering process parameters including film thickness and substrate temperature were investigated. The crystallite sizes of the ZnO films were extracted from the measured X-ray diffraction patterns. The correlation of the crystallite size of the ZnO films with the film thickness and the substrate temperature will be discussed in this paper.

Abstract: Additive Manufacturing (AM) - is a technology that fabricates the parts directly from 3D CAD model without the need of any process planning. The convergence of AM and life science has evolved into a new paradigm called Bio-Additive Manufacturing (BAM). In this paper, Hydroxyapatite (HA) powder was coated over the customized implant, which will serve as a good candidate for bone substitutes due to its chemical and structural similarity to bone. Computer Tomography (CT) scan data of human tibia bone was collected and stacked in MIMICS image processing software, which converts it into 3D data, then implant was fabricated using Selective Laser Sintering (SLS), an AM technique with polyamide powder. Hydroxyapatite powder was synthesized by wet chemical process and coated over implant using plasma spray coating machine. This coating will produce an intermediate region between the bone and the implant, which will stimulate the tissue growth and bone contact. Micrograph of coated and uncoated implant was analyzed using SEM and EDX. For In-Vitro study human mesenchymal cell was cultured over the coated implant. The viability and proliferation of the cells was studied by examining the morphology of the cell. Thus the implant was fabricated using SLS technique and coated with hydroxyapatite powder which exhibits a favorable and good response to enhance tissue growth.

Abstract: It is difficult to obtain good adhesive property on the titanium surface. Thus, to plate metal on the titanium, oxide layer must be eliminated by using an intermediate pre-treatment. However, this process involves several steps and even then the level of addition between the plated metal and the titanium is poor. This paper presents the results of the thickness and morphology of nickel plating to titanium sample with the effects of the types of solutions. The morphology and thickness of nickel plated was studied using scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM). The results show nickel sulphamate solution gave highest rate of plating compared to the other solutions while all chloride solution produces much fine grain structure. By using high speed electroplating and by maintaining a narrow gap between the anode and the cathode, it has been possible to electrodeposit Ni directly on Ti without any pre-treatment or even any conventional cleaning process before plating.