JST Vol. 21 (1) Jan. 2013 - Pertanika Journal - Universiti Putra ...

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CONCLUSION Heng, S. C., Ibrahim, Z. B., Suleiman, M. and Ismail, F. In this paper, it was observed that the 2-point BBDF achieved better results in terms of the accuracy of the method as well as the execution time. Therefore, it can be concluded that the 2-point BBDF is suitable for solving stiff DDEs. ACKNOWLEDGEMENTS This work was fully supported by the Institute of Mathematical Research, Universiti Putra Malaysia, under the Fundamental Scheme Research Grant (Project code: 01-09-09-681FR). REFERENCES Bellen, A., & Zennaro, M. (2003). Numerical Methods for Delay Differential Equations. New York: Oxford University Press. Bocharov, G. A., Marchuk, G. I., & Romanyukha, A. A. (1996). Numerical solution by LMMs of Stiff Delay Differential systems modelling an Immnune Response. Numer. Math., 73, 131-148. Driver, R. D. (1976). Ordinary and Delay Differential Equations. New Year: Springer-Verlag. Ibrahim, Z. B., Othman, K. I., & Suleiman, M. (2007). Implicit r-point Block Backward Differentiation Formula for Solving First Order Stiff ODEs. Applied Mathematics and Computation, 186, 558-565. Ismail, F. (1999). Numerical Solution of Ordinary and Delay Differential Equations by Runge-Kutta Type Methods (Ph.D Thesis dissertation). Universiti Putra Malaysia, Malaysia. Ismail, F., Al-Khasawneh, R. A., Lwin, A. S., & Suleiman, M. (2002). Numerical Treatment of Delay Differential Equations by Runge-Kutta Method Using Hermite Interpolation. Matematika, 18(2), 79-90. Lambert, J. D. (1993). Numerical Methods for Ordinary Differential Systems: The Initial Value Problem. Chichester, England: John Wiley and Sons. Oberle, H. J., & Pesch, H. J. (1981). Numerical Treatment of Delay Differential Equations by Hermite Interpolation. Numer. Math., 37, 235-255. Richard, L., Burden, J., & Douglas, F. (1993). Numerical Analysis. Boston: PWS-Kent Pub. Co. Roth, M. G. (1980). Difference Methods for Stiff Delay Differential Equations (Master Thesis dissertation). University of Illinois, Illinois. William, H. P., Saul, A. T., William, T. V., & Brian, P. F. (2007). Numerical Recipes: The Art of Scientific Computing. New York: Cambridge University Press. 44 Pertanika J. Sci. & Technol. 21 (1): 283 - 298 (2013)
ISSN: 0128-7680 © 2013 Universiti Putra Malaysia Press. Pertanika J. Sci. & Technol. 21 (1): 45 - 58 (2013) SCIENCE & TECHNOLOGY Journal homepage: http://www.pertanika.upm.edu.my/ Effects of Process Temperature and Time on the Properties of Microwave Plasma Nitrided Ti-6Al-4V Alloy Y. Yusuf*, J. M. Juoi, Z. M. Rosli, W. L. Kwan and Z. Mahamud Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka, Durian Tunggal, 76109 Melaka, Malaysia ABSTRACT Titanium alloy (e.g. Ti-6Al-4V) has an excellent combination of properties. However in many cases, the application is limited because of the poor wear property. In this work, a surface modification (plasma nitriding) is carried out to improve the surface properties of Ti-6Al-4V, as a treatment prior to a hardcoating deposition, leading to a duplex coating system. This is an effort to improve the surface and near surface property of Ti-6Al-4V. Plasma nitriding is performed utilizing microwave plasma method in 25% Ar- 75% N 2 atmosphere at temperatures of 600°C and 700°C for different processing times (1, 3 and 5 hours). The phase and microstructure of plasma nitrided substrate were characterized by using X-ray diffraction (XRD) and Scanning electron microscopy (SEM). The plasma nitrided Ti-6Al-4V properties (surface roughness, surface hardness and case depth) were determined using profilometer and microhardness, respectively. Results obtained showed a significant increase on the surface hardness of Ti-6Al-4V. This is due to the formation of TiN and Ti 2N phases in the form of compound layer. Besides, it shows that the diffusion of nitrogen into the Ti-6Al-4V substrate produces case depth up to 130 µm and this contributes to the improvement of the near surface hardness due to the changes in the microstructures. It was also found that the surface hardness and surface roughness increased with the increases in the process temperature and times. Keywords: Ti-6Al-4V, surface modification, plasma nitriding, microwave plasma Article history: Received: 26 April 2011 Accepted: 22 November 2011 E-mail addresses: yusliza.yusuf@yahoo.com (Y. Yusuf), jariah@utem.edu.my (J. M. Juoi), zmr@utem.edu.my (Z. M. Rosli), Kwailoon86@gmail.com (W. L. Kwan), zainab.mahamud86@gmail.com (Z. Mahamud) *Corresponding Author INTRODUCTION Titanium and its alloys have received extensive interest due to their excellent combination of properties, such as excellent corrosion resistance, high strength to weight ratio, high strength at elevated temperatures, low modulus elasticity and biological compatibility. Besides, titanium and its alloys
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Assessment of Heavy Metal Pollution
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Physico-Chemical and Electrical Pro
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Statistical Analysis Norhashila Has
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INTRODUCTION Tajau, R. et al. A hig
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Tajau, R. et al. double bond) and C
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Aji, I. S., Zinudin, E. S., Khairul
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Aji, I. S., Zinudin, E. S., Khairul
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CONCLUSION Aji, I. S., Zinudin, E.
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D. Bachtiar, S. M. Sapuan, E. S. Za
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TABLE 1: (continue) 4 D. Bachtiar,
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REFERENCES N. Maizatul, I. Norazowa
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CBIR Using Colour and Shape Fused F
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Toward Automatic Semantic Annotatin
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Issues on Trust Management in Wirel
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Trust Value MF-ID 1 0.8 0.6 0.4 0.2
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A Negation Query Engine for Complex
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REFERENCES A Negation Query Engine
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The Problem Association Rule Mining
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Association Rule Mining threshold t
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Association Rule Mining must be sor
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Association Rule Mining On the othe
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Association Rule Mining Quinlan, J.
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Che Mustapha Yusuf, J., Mohd Su’u
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REFERENCES Yogan Jaya Kumar, Naomie
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Hasiah Mohamed@Omar, Azizah Jaafar
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The Role of Similarity Measurement
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TABLE 5: Winners MRS The Role of Si
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REFEREES FOR THE PERTANIKA JOURNAL
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Guidelines for Authors Publication
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table should be prepared on a separ
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Usability of Educational Computer G
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