Suhaimi Illias
Thumbnail Image
Preferred name
Suhaimi Illias
Official Name
Suhaimi, Illias
Alternative Name
Ilias, Suhaimi
Illias, S.
Bin Illias, Suhaimi
Iliasb, Suhaimi
Main Affiliation
Scopus Author ID
54920300100
Researcher ID
ABB-5405-2020

Research Output

Filters

7
Reset filters

Settings
Now showing 1 - 7 of 7
Thumbnail Image
Publication

The role of gas-phase dynamics in interfacial phenomena during few-layer graphene growth through atmospheric pressure chemical vapour deposition

2020-02-14 , Fauzi F.B. , Ismail E. , Syed Abu Bakar S.N. , Ismail A.F. , Mohamed M.A. , Md Din M.F. , Suhaimi Illias , Ani M.H.

The complicated chemical vapour deposition (CVD) is currently the most viable method of producing graphene. Most studies have extensively focused on chemical aspects either through experiments or computational studies. However, gas-phase dynamics in CVD reportedly plays an important role in improving graphene quality. Given that mass transport is the rate-limiting step for graphene deposition in atmospheric-pressure CVD (APCVD), the interfacial phenomena at the gas-solid interface (i.e., the boundary layer) are a crucial controlling factor. Accordingly, only by understanding and controlling the boundary-layer thickness can uniform full-coverage graphene deposition be achieved. In this study, a simplified computational fluid dynamics analysis of APCVD was performed to investigate gas-phase dynamics during deposition. Boundary-layer thickness was also estimated through the development of a customised homogeneous gas model. Interfacial phenomena, particularly the boundary layer and mass transport within it, were studied. The effects of Reynolds number on these factors were explored and compared with experimentally obtained results of the characterised graphene deposit. We then discussed and elucidated the important relation of fluid dynamics to graphene growth through APCVD.

View
Thumbnail Image
Publication

High Temperature Oxidation of T91 Alloy of Steam Reformer

2023-01-01 , Rosdin M.R.H. , Ismail A.A.M. , Hamid A.M.A. , Purwanto H. , Suhaimi Illias , Bakar S.N.S.A. , Ani M.H.

Steam plays a significant role in the reforming process of hydrogen. It is generated in a waste heat recovery unit at temperature of 650 ℃. Along with the high operating temperature, the situation promotes acceleration of high temperature oxidation. This will cause fouling and spalling of oxide scales at the boiler tube. Eventually, fouling will reduce heat transfer between the tube and steam generated, causing a higher temperature is needed to produce steam. Until now, the only approach used by the industry is to manually replace the corroded boiler tube. Other than that, many studies have been conducted on the behavior of boiler tubes at temperatures exceeding 800 °C. However, to our knowledge, no “in-situ” study has been done to investigate the high temperature electrochemistry aspect of boiler tubes. A review conducted by B.A Pint [1] in his paper mentioned that it is notoriously difficult to imitate the harsh environments in laboratory scale. Popov [2] stated that the only available method to decrease corrosion rate at high temperature corrosion and hot corrosion is only by implementing protective coatings. This project was carried out to investigate the corrosion potential of T91 boiler tube at 650 °C for 30 min, 1 h, 2 h, 8 h, and 12 h, measure the current density (Icorr) by calculating corrosion potential (Ecorr) value using Tafel Extrapolation and determine the current conductivity of oxygen gas at 650 ℃. Apart from that, the oxide layer thickness at exposed temperature is also determined to measure the oxidation kinetics. The study concludes that there was an increase of 8.49% in current conductivity between the blank experiment and T91 alloy conductivity test. The oxide layer formed on the sample is significant to calculate the oxidation kinetics of the sample using parabolic rate constant (Kp), resulting with the value of 6.78 × 10–14 m2s−1.

View
Thumbnail Image
Publication

Prediction of maximum spreading time of water droplet during impact onto hot surface beyond the Leidenfrost temperature

2021-12-01 , Suhaimi Illias , Suhaila Hussain , Rahim Y.A. , Muhammad Asri Idris , Mohamad Ezral Baharudin , Ismail K.A. , Ani M.H.

When a water droplet impacts on a heated surface in the film boiling regime, it will spread, recede, and finally bounce off from the heated surface. These unique liquid-solid interactions only occur at high surface temperatures. Our main objective in this research is to measure the maximum spreading and residence time of the droplet and the findings were compared to theory. We focused our study in the film boiling regime. Brass material was selected as the test surface and was polished until it became a mirror polished surface. The temperature range for this experimental work was between 100 °C up to 420 °C. Degassed and distilled water was used as the test liquid. The high speed video camera recorded the images at the rate of 10,000 frames per second (fps). As a result, it was found that the experimental value of maximum spreading and residence time agreed closely with the theoretical calculation. A new empirical formula that can be used to predict the maximum spreading time in the film boiling regime is also proposed.

View
Thumbnail Image
Publication

Slagging of Coal Blends: Comparison between Pre-Blended and in Furnace Blend

2020-07-09 , Somad Abdul Latiff A. , Musa M. , Anhar Z. , Suhaimi Illias , Ani M.H.

Coal blending technique in electric generating power plant has been widely used to reduce coal consumption cost. However, due to various coals from different places blended together, it had caused problems. Slagging formed during the operations can reduced boiler efficiency, resulting high costs for maintenance caused by blockage, corrosion and erosion. Many empirical indices and predictive method have been developed to minimize these problems but most are unreliable for coals from different places and many predictive methods are carried out in different environment. In this research, the method starts from fabricating the pre-blended and in furnace blend techniques at a local coal pulverized power plant. After feeding the coal blends for coal trial burn, the resulting ash deposition are collected at the burner where slagging usually occurs. The raw coals in used and the slagging samples are then characterized and determine their crystalline phase and compositions by using X-Ray Diffraction (XRD) and Sacnning Electron Microscope Energy Dispersive Xray (SEM/EDX). From XRD analysis, compounds such as quartz, cristobalite low and manganosite were found as main species in ash deposition at all location of collected slagging. However, there are also some compound exist at specific location with specific technique being used. In the burner area for pre blended technique, compound Al2SiO5, Mg2Al4Si5, KNO2 and FeO was found, whereas in furnace blend K2Mn2(SO4)3 was found. At bottom part of the furnace, pre-blended graphite was presence and in furnace yield MnO2 and Al2SiO5. At top part where superheater reside, the existence of mullite, Al2(Al2.5Si1.5)9.75 was found for pre-blended technique and microcline, KAlSiO3O8 is observed from in furnace blend technique. From the EDX analysis, in furnace technique shows more complete combustion and feasible for less slagging inside the furnace compared to pre-blended technique.

View
Thumbnail Image
Publication

Metal Dusting Led Failure in a High-Temperature Condenser

2023-01-01 , Kaderi A. , Bakar S.N.S.A. , Ani M.H. , Suhaimi Illias , Osman M.S.

Corrosion is a metallurgical problem that occurs frequently in a power plant, plant inevitable, especially in the present days, since higher efficiency of a power plant is required and thus the process temperature is increasing. Choosing the right materials for pipeline is very crucial since it is affecting the service life and operational reliability. The research is done to study the oxidation behaviour of ferritic alloy for power plant. A failed component from a gas combined cyclic thermal power plant was received and a failure analysis is done to investigate the cause of failure of the equipment. Results from the analysis suggested that the pipe was exposed to high temperature oxidation and metal dusting. Metal dusting mechanism and how it affects materials in high temperature condition is then identified and explained in this work.

View
Thumbnail Image
Publication

Electrochemical Monitoring of Oxygen Potential on Fe-Cr Alloy Surface During High Temperature Oxidation in Dry and Humid Conditions

2023-01-01 , Ani M.H. , Purwanto H. , Musa M. , Suhaimi Illias , Kaderi A. , Salim N. , Rahim M.H.A. , Sutjipto A.G.E.

The formation of an external Cr2O3 scale is important to obtain the oxidation resistance of Fe–Cr alloys at high temperatures. It is well known that the critical concentration of Cr to form a protective external scale of Cr2O3 in humid conditions is higher than that in dry conditions, and the criterion is expressed as Wagner’s equation (Rapp in Acta Metall 9:730, 1961) [1]. A lot of mass gain data and metallographic surveys are required to determine the above criterion experimentally. A method of continuous monitoring of surface oxygen potential by oxygen concentration cell using stabilized zirconia has been applied to the oxidation of Fe-Cr alloy in order to check the protectiveness of the scale. The objective of this study is to measure surface oxygen potentials on Fe-0-17 wt% Cr alloys in Ar-21% O2 gas in dry condition and Fe-10-22 wt% Cr alloys in Ar-20% O2-20% H2O gas in humid condition at 1073 K up to 20 ks. In dry condition, the surface oxygen potentials of Fe with more than 10 wt% Cr alloys were close to the oxygen potential of the atmosphere immediately after the heating period. It indicates that a protective Cr2O3 scale formed on these alloys at the early stage of oxidation. However, the surface oxygen potentials of these same composition alloys were lower in humid conditions than that in dry, which suggests a higher oxidation rate. This paper demonstrated that the protectiveness of scales formed on Fe–Cr alloys can be evaluated in situ in a few hours, which is beneficial to assess the high temperature oxidation of metals.

View
Thumbnail Image
Publication

Effect of Oxygen Gas Exposure on T91 Alloy at High Temperature Oxidation of Steam Reformer

2023-01-01 , Rosdin M.R.H. , Ismail A.A.M. , Hamid A.M.A. , Purwanto H. , Suhaimi Illias , Bakar S.N.S.A. , Ani M.H.

Steam-Methane Reforming (SMR) is one of the most economical ways to produce hydrogen from natural gas. Steam reforming industry is hugely relied on using supercritical power plant where the working temperature of the plant must exceed 600 °C. Along with the high operating temperature, the situation promotes the acceleration of high temperature oxidation. This will cause fouling and spalling of oxide scales at the boiler tube. Eventually, fouling will reduce heat transfer between the tube and steam generated, causing a higher temperature is needed to produce steam. Until now, the only approach used by the industry is to manually replace the corroded boiler tube. Other than that, many studies have been conducted on the behavior of boiler tubes at temperatures exceeding 800 °C. However, to our knowledge, no study has been done to investigate the air electrolyte substrate interfacial electrochemical reaction at high temperature. This project was carried out to investigate the corrosion potential of T91 boiler tube at 650 °C for 2 h, 8 h, and 12 h, measure the current density (Icorr) by calculating corrosion potential (Ecorr) value using Tafel Extrapolation and determine the oxidation potential of oxygen gas at 650 °. The oxide layer thickness at exposed temperature was determined to measure the oxidation kinetics. The study concludes that there was an increase of 8.49% in current conductivity between the blank experiment and T91 alloy oxidation potential test. The oxidation process was following the parabolic rate law which manifest that the corrosion is controlled by ionic diffusivity in the oxide layer. The oxide layer formed on the sample has an average thickness of 54.10 μm and this value can be used to calculate the oxidation kinetics of the sample using parabolic rate constant, Kp, resulting with the value of 6.78 × 10−14 m2/s.

View