Skip Navigation LinksVolume : Volume 21 No.1 2013

  
  
  
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zamzuri.pdfIMPROVEMENT OF CORROSION RESISTANCE OF AZ91D MAGNESIUM ALLOY BY LANTHANUM-BASED CONVERSION COATING
  
ABSTRACT: 
Chemical conversion coating by rare earth metal salt solution was considered as an alternative to chromate conversion coating in order to improve the corrosion resistance of magnesium alloys. In this study, lanthanum-based conversion coatings formed on AZ91D magnesium alloy were characterized, and the effect of treatment time period was discussed. SEM images showed that specimen treated with solution containing lanthanum nitrate and magnesium nitrate for 30 min has formed an oxide layer on the entire surface of magnesium alloy. EDS analysis has confirmed that the layer was mainly consisted of oxygen and lanthanum elements. Corrosion test indicated that lanthanum-based conversion coating has a better corrosion resistance than as-received specimen at all treatment conditions.         

KEYWORDS: Corrosion protection, magnesium alloy, conversion coating, rare earth element (REE) 

Author: M. Z. M. Zamzuri, N. F. W. M. Sidik, M. N. B. Derman, S. Norbahiyah and M. Mat Salleh
Year: 2013
tan_yong_nee.pdfSOLAR PHOTOCATALYTIC DECONTAMINATION AND DISINFECTION OF WATER
  
ABSTRACT: 
Photocatalysis using TiO2 for detoxification of contaminated water is most extensively been studied and developed today as of its practical applications to treat water contaminants. Photocatalytic treatment can be useful for addressing hazardous contaminants such as phenols, agricultural wastes, pesticides and etc. The objective of this study was to demonstrate whether detoxification of pesticide contaminated water by TiO2 photocatalysis process is possible.  The performance of photocatalytic degradation of pesticide contaminated groundwater has been studied at pilot scale with the TiO2 photocatalyst. The study showed that 80 % and 54 % mineralization has been attained after 24 hours of UV and solar radiation, respectively.                        
KEYWORDS: Photocatalytic treatment, UV, Solar, TiO2     

Author: Tan Yong Nee, Chen Sau Soon, Izham Bakar, Zulkarnain Abdullah
Year: 2013
ropien.pdfPHOSPHOLIPID BASED VESICULAR SYSTEM FOR TRANSDERMAL AND DERMAL DELIVERY
  
ABSTRACT:
Phospholipid based vesicular appears to be most promising transdermal and dermal delivery system due their merits over other delivery systems. This article reviews the types of phopholipid based vesicular system such as liposomes, transferosomes and ethosomes  and their  mechanism of skin permeation .  It also provides an information on the method of preparation and  application of the system.         

KEYWORDS: Phopholipid based vesicular, transdermal and dermal delivery, liposomes, transferosomes, ethosomes 

Author: Ropien Jokiman
Year: 2013
rahman.pdfSINTERING OF WARM FORMED COMPONENTS IN INERT GAS FIRED FURNACE
  
ABSTARACT: 
This paper presents the results of an experimental investigation of the sintering of metallic components formed at above ambient temperature.  The feedstock was prepared through mechanically mixing of iron powder ASC 100.29 with 0.4 wt% and 0.8 wt% zinc stearate for 30 minutes.  The powder mass was then shaped at 120ºC and 180ºC through uniaxial compaction method.  The defect-free green compacts were then sintered at argon gas fired sintering furnace at different sintering schedules.  The heating rates were 5 ºC/minutes and 10 ºC/minutes where the cooling rates were the reverse of the heating rates.  The holding times were 30 minutes and 60 minutes whereas the sintering temperature was fixed at 1000 ºC.  The sintered products were characterized through mechanical testing and microstructure examination.  The results revealed that both forming and sintering parameters significantly affect the final quality of the products.     

KEYWORDS: Warm forming, sintering, mechanical properties, microstructure.       

Author: M. M. Rahman*, T. J. Saktisahdan & H. Y. Rahman
Year: 2013
omar.pdfSTRESS RELAXATION BEHAVIOUR AND MECHANISM OF HEAT TREATED INCONEL 718 IN HIGH TEMPERATURE ENVIRONMENTS
  
ABSTRACT:
The stress relaxation behaviour of heat treated nickel-base superalloy Inconel 718 at high temperature was investigated. Solution treatment was applied on the as-received material at    980 oC for 1 hour before water quenching followed by double aging treatments at 720 oC for 8 hours and 621 oC for 8 hours, then cooled in air.The stress relaxation test was conducted at 1 % strain at different test temperatures of 550 oC, 650 oC and 750 oC. The tests were carried out for a total of 72 hours. The tests were interrupted at 3 hours and 48 hours to investigate the evolution of microstructure and changes in material properties by using Scanning Electron Microscope (SEM) and X-Ray Diffractometer (XRD). The results showed that thermal dependent stress increased with decreasing temperature. In contrast, stress relaxation rate increased with increasing temperature. Microstructure observation by SEM showed that recovery process occurred. This was further supported by the decrease in dislocation density with increase in time and temperature, which is in-line with the Vickers micro-hardness results.      ]

KEYWORDS: Heat treatment, stress relaxation, recovery, microstructure, Inconel 718 

Author: O. Bapokutty, Z. Sajuri and J. Syarif
Year: 2013
mukhruz.pdfSTUDY OF SOFT X-RAY EMISSON FROM LASER PRODUCED PLASMA OF DIFFERENT MATERIAL
  
ABSTRACT: 
The soft X-ray emission from Laser produced Plasma of different materials has been investigated. We used Nd:YAG (1.06 µm) laser, of energy 10 mJ, and FWHM 12 ns to produce plasma from different target materials where X-rays were generated from the plasma plume due to laser matter interaction. The experiments were performed under vacuum of approximately 1 mTorr in a stainless steel chamber, consisting of eight ports. Tungsten, silver, aluminum and copper were used as the target materials for the investigation. The soft X-rays were detected by 10 micron Al filtered PIN photodiode (BPX 65) where all the X-rays signals were stored in the 200 MHz digital storage oscilloscope. It was found that tungsten is a poor source of soft X-rays as compared with the silver, aluminum and copper.     

KEYWORDS: Laser Produced Plasma, soft X-Rays, plasma. 

Author: Mahrukh Bukhari, S.J. Iqbal, M Iqbal, M S Rafique
Year: 2013
jabir.pdfEFFECT OF ATMOSPHERE ON THE SINTERED TITANIUM ALLOY PRODUCED BY METAL INJECTION MOLDING (MIM) TECHNIQUE
  
ABSTRACT: 
Titanium alloy produced as an implant for craniofacial application was prepared through Metal Injection Molding (MIM) technique. The MIM is an efficient method for the high volume production of complex shaped components. In normal atmosphere, the implants will react with graphite heating element at high temperature to form titanium carbide (TiC) which was also due to its reactions with binder system. Therefore the influence of the atmosphere during sintering of implants at high temperature was investigated in order to improve the properties of sintered titanium alloy implant. This reaction can be avoided by introducing argon gases or in vacuum atmosphere during the sintering process. The implant which contained titanium alloy powder and binder system based on palm stearin (PS) and polyethylene (PE), are mixed using the z-blade mixer. The binder system was then removed through the debinding process and sintered in either argon or vacuum atmosphere at     1250 °C for 4 hours. The result showed that the implants sintered in argon at 1250 °C, experienced an increased in density of 4.525 g/cm3, as well as hardness, 458 HV compared to the implants sintered in vacuum atmosphere; which is slightly lower with density of 4.512 g/cm3 and hardness of 426 HV. The high densification of implant in argon was achieved due to the each individual particles powder which became more interconnected to each other. As opposed to the normal atmosphere which produced TiC, sintering in argon results in improved crystallinity of the grain growth which is smaller compared with the vacuum atmosphere. The XRD (X-ray Diffraction) pattern also reveals that addition of argon gas in the sintering process, effectively reduce the formation of TiC.     

KEYWORDS: implant, palm stearin, titanium alloy, argon and vacuum atmosphere 

Author: Muhammad Jabir Suleiman, Mohamad Azmirruddin Ahmad, Nurzilla Mohamed, Yusli Mohamad Junus, Rosdi Ibrahim, Mazlan Mohamad, Mohammed Rafiq Abdul Kadir, Noor Hayaty Abu Kassim, Roila Awang and Shamsul Muhammad
Year: 2013
ahmad_aswad.pdfEFFECT OF CARBON ADDITION ON THE DENSIFICATION AND PROPERTIES OF SINTERED CEMENTED CARBIDE (WC-Co)
  
ABSTRACT:
Hardmetal is a well known material in metal cutting and wear related applications. Cemented carbide (WC-Co) is the most widely used for this application, in which addition of carbon to the WC-Co improves densification process. This study investigates the effect of carbon addition on the densification and properties of sintered WC-Co. The samples are fabricated using powder metallurgy technique, in which the powders are compacted at 625 MPa, cold-isostatic pressed at 200 MPa and sintered at temperatures between 1350 °C to 1450 °C under nitrogen-based atmosphere. The physical and mechanical properties of the samples were analyzed. The study reveals that addition of  0.8 % of carbon and above will greatly reduce the density of the WC-Co sintered powders.       Keywords: WC-Co, powder metallurgy, carbon addition, nitrogen-based 

Author: Ahmad Aswad Mahaidin*, Mohd. Asri Selamat, Samsiah Abdul Manaf and Talib Ria Jaafar
Year: 2013