Nanozarah Co-Ni-Cu telah disediakan dengan kaedah elektropengendapan pada keupayaan pengendapan -925 mV (SCE) menggunakan larutan sulfat (0.018M Co2++ 0.180M Ni2+ + 0.002M Cu2+) yang mengandungi surfaktan Glukopon 215 CSUP dan juga tanpa surfaktan. Kesan kepekatan surfaktan terhadap saiz dan sifat magnet nanozarah Co-Ni-Cu yang terhasil telah dikaji. Analisis morfologi permukaan endapan yang diperoleh dilakukan dengan menggunakan mikroskop elektron imbasan pancaran medan (FESEM) manakala sifat magnetnya diselidiki dengan menggunakan magnetometer getaran sampel (VSM). Nanozarah Co-Ni-Cu yang disediakan daripada larutan yang mengandungi Glukopon 215 CSUP didapati berbentuk sfera dengan saiz berskala nanometer. Saiz zarah paling kecil ialah lebih kurang 50 nm, diperoleh pada kepekatan surfaktan 5 %v, iaitu kepekatan paling tinggi yang dikaji dalam kajian ini. Kepaksaan (Hc) didapati lebih tinggi pada sampel yang disediakan daripada elektrolit yang mengandungi surfaktan berbanding tanpa surfaktan.
Heat treatment was introduced onto the aluminum coated low carbon steel to promote the formation of thin layer of oxide for enhancement of oxidation protection of steel. This process has transformed the existing intermetallic layer formed during hot dip aluminizing process. Experiment was conducted on the low carbon steel substrates with 10mm x 10mm x 2mm dimension. Hot dip aluminizing of low carbon steel was carried out at 750 ºC dipping temperature in a molten pure aluminum for 5 minutes. Aluminized samples were heat treated at 600 ºC, 700 ºC, 800 ºC, and 900 ºC for 1 hour. X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and EDAX were used in investigation. From the observation, it showed the intermetallic thickness increased with the increase in temperature. The result of EDAX analysis revealed the existence of oxide phase and the intermetallics. The XRD identified the intermetallics as Fe2Al5 and FeAl3.
Even though a lot of new advanced materials have been developed nowadays, steel remains a major material in construction, automobiles, appliances, industrial machinery as well as in the nuclear industry. Due to steel easily corroded, a proper surface protection is required to avoid any failures and extended the life cycle of the components. Surface coating is an efficient and economical method to obtain desirable material surfaces properties. Hot dip aluminizing technique was utilized in this study. Experiments have been conducted on the mild steel substrates with 12mm diameter. Prior to hot dipping process, observation on grain growth at three different temperatures had also been conducted to understand the behaviour of steel under application of heat. The substrates were heated at 700ºC, 800ºC and 900ºC for 1 hour and the microstructure was analyzed. The temperature of 800C was chosen for hot dipping. The substrates were dipped into the molten aluminum maintained at temperature 800ºC for 2,4,6,8,10,15 and 20 minutes. Optical microscopy and energy dispersive X-ray spectroscopy were used in this investigation. From the microstructure observation, it showed the appearance of intermetallic layer covered by the top layer of Al on the mild steel substrate increased with the increase in dipping time ranging from 36 to 282μm. The result of EDX analysis revealed the existence of Fe and Al in form of Fe2Al5 phase for all the dipping time.
Al-Si/SiC composites with the fraction of 5 and 15 wt. % fine SiC particles were fabricated using stir casting process by which SiC powders were poured into aluminium melt and cast in a stainless steel mould to form ingot. Characterization by X-ray diffraction (XRD) analysis showed the presence of constituent and intermetallic materials in the composites. Microstructure study revealed that both fine and course particles scattered in the Al-Si matrix. The characterization of thermal properties showed that the thermal conductivity and coefficient of thermal expansion decreased with the increase in SiC content. The conductivity and expansion behavior is correlated to the microstructure and weight fraction of the SiC particles. Meanwhile, the hardness of the composite increased with the increasing of SiC particles in the composites.
A single wall single image x-ray radiographic technique was adopted to investigate thickness variation of steel specimens caused by uniform corrosion. The ability of the 100 kV-160 kV x-rays to produce a meaningful film density for steel was also investigated. The thickness contour maps of corroded steel plates were found matching with the x-ray film density contour maps of the plates. The results confirm that x-ray radiography can be used to detect the thickness reduction of steel caused by uniform corrosion.
Bagi mengesan perubahan ketebalan keluli akibat kakisan seragam maka radiografi sinar-x teknik imej tunggal dinding tunggal telah digunakan. Kemampuan sinar-x 100 kV-160 kV menghasilkan ketumpatan filem yang sesuai untuk keluli telah juga dikaji. Peta kontur ketebalan bagi spesimen kepingan keluli yang telah mengalami kakisan seragam didapati sepadan dengan peta kontur ketumpatan filem radiografi sinar-x bagi spesimen tersebut. Kajian ini menunjukkan radiografi sinar-x boleh digunakan bagi mengesan penipisan keluli akibat kakisan seragam.
Keberkesanan perencatan benziltrietilamonium klorida (BK) terhadap perlindungan kakisan keluli karbon di dalam 1 M asid asetik telah dianalisis dengan menggunakan kaedah ujian kehilangan berat. Matlamat kajian adalah untuk menilai tahap kecekapan perencatan BK berdasarkan perubahan nilai kepekatan perencat berkenaan dan suhu. Analisis kehilangan berat menunjukkan kadar kakisan keluli karbon berjaya dikurangkan dengan penggunaan kepekatan BK yang lebih tinggi dan nilai kecekapan perencatan BK mencapai sehingga 70%. Namun kadar kakisan didapati meningkat selari dengan peningkatan suhu. Analisis termodinamik mendapati perencatan BK berjaya mengurangkan proses pelarutan ion-ion logam melalui pembentukan lapisan filem nipis pada permukaan keluli karbon. Analisis juga menunjukkan sebatian BK berupaya menjerap pada permukaan keluli karbon melalui kedua-dua kaedah penjerapan fizikal dan kimia. Proses penjerapan BK pada permukaan keluli karbon didapati lebih menjurus kepada model isoterma penjerapan Langmuir. Analisis morfologi menggunakan mikroskop imbasan elektron turut mengesahkan berlakunya perencatan BK pada tapak permukaan keluli karbon. Keseluruhan kajian mendapati sebatian BK berupaya melindungi keluli karbon daripada mengalami kakisan di dalam medium asid asetik.
Nitridation behaviour of Al-Mg-Si alloys was studied as a function of temperature by means of thermogravimetry method. A reactive gas, N2-4%H2 at a rate of 10 ml/min was purged into the thermogravimetry analyser chamber. The Al alloys were heated from 25oC to 625oC at the heating rate of 15oC/min and then reduced to 3oC/min until it reached 1500oC. It was found that by varying the amount of Mg and Si in Al-Mg-Si alloys significantly influenced the growth of the composites. A differential thermogravimetric curve shows the Mg containing alloys experienced many steps of chemical reactions. This indicates that besides AlN presence as a major phase, other compounds also exist in the final product. The X-ray diffraction results confirmed the existence of oxide phases such as a-Al2O3, MgAl2O4 and MgO in addition to residual Si and Al metal. The presence of oxide compounds is believed to be due to the reaction between the alloying elements and residual oxygen gas left in the reaction atmosphere. It was also found that Si could play a role in promoting the weight gain of the composite produced. The heating rate has also a profound effect on the weight gain, whereby higher heating rate resulted in low yielded of AlN during the nitridation reaction of the Al-Mg-Si alloys.
Ancaman biokakisan akibat aktiviti bakteria penurun sulfat (SRB) pada saluran paip keluli karbon dalam industri petroleum boleh menjejaskan kelancaran aliran pengangkutan minyak mentah dan meningkatkan kos pengoperasian. Usaha bagi melindungi keluli karbon serta pengawalan SRB masih memerlukan kajian yang berterusan. Dalam kajian ini, keberkesanan tetrametilamonium bromida (TMB), karboksimetil trimetilamonium (BTN) dan benzalkonium klorida (BKC) bagi melindungi keluli karbon di dalam persekitaran yang mengandungi SRB diuji melalui kaedah pengutuban elektrokimia dinamik (PED) dan morfologi keluli karbon dianalisis menggunakan mikroskop elektron imbasan. Analisis PED mendapati penggunaan TMB, BTN dan BKC masing-masing berupaya mengurangkan kadar kakisan sehingga 0.13, 0.56 dan 0.17 mm/thn berbanding 8.91 mm/thn pada larutan kawalan yang mengandungi SRB. Morfologi permukaan biofilem mengesahkan kadar pertumbuhan SRB serta hasilan metabolisme bakteria ini turut mengalami penyusutan. Kajian ini menunjukkan dua mekanisme kawalan kakisan didapati berlaku iaitu mekanisme perencatan kakisan melalui penjerapan sebatian amonium kuaterner pada permukaan keluli karbon serta berlakunya proses tindak balas mitigasi sebatian ini dengan bakteria SRB. Kesimpulannya, TMB, BTN dan BKC didapati berupaya melindungi keluli karbon daripada mengalami kakisan akibat aktiviti SRB.
The performance of pipeline system used in petroleum industry is crucially declined by natural microbial activities and
demanding extra operational cost. Requirement on high capability of functional substances is attracting worldwide
research interest. The aim of this paper was to study the effectiveness of benzyltriethylammonium chloride (BTC) on
reducing the activity of a consortium bacteria consisting of sulfate-reducing bacteria (C-SRB). C-SRB was isolated from
tropical crude oil and enumeration of this consortium was measured by viable cell count technique. The effectiveness of
BTC was calculated from potentiodynamic polarization method and biofilm analysis was performed by scanning electron
microscope. The viable cell count technique indicated that the maximum growth of C-SRB was approximately 160 trillion
CFU/mL at 7 days incubation period. BTC was capable of reducing biocorrosion activity due to adsorption process and
mitigating SRB species. Biofilm analysis has proven that C-SRB activity is minimized due to less presence of bacterial
growth, extracellular polymeric substances and corrosion product. In conclusion, BTC is capable to inhibit C-SRB activity
on biocorrosion of carbon steel pipeline.
This work investigates the micromechanical properties of Sn96.5Ag3.0Cu (SAC 305) on Immersion Tin (ImSn) surface
finished after subjected to high temperature storage (HTS) at 180°C for 200 to 1000 h period. Nanoindentation approach
was used to measure the micromechanical properties of the solder. It was observed that the indentation depth and plastic
depth were increased and a clear trend of decreasing hardness as opposed to the increasing reduced modulus as the HTS
time lengthened. The plasticity-asscociated properties become stronger meanwhile the elasticity-associated properties
decreased with the HTS time. These findings indicate that nanoindentation approach can clearly determine the plastic
and elastic deformation occurance throughout the test.