MyMedR

A study has been conducted on 198 employees of a steel-mill industry. These participants were examined for mucosal lesions in the oral cavity and including the commissures and vermillion borders of the lips. The prevalences of 16 types of lesions are reported.

Matched MeSH terms: Metallurgy

Fulltext A delayed unusual presentation of a penetrating foreign body

Lee ST

Singapore Med J, 1992 Jun;33(3):304-5.

PMID: 1631596

Complications resulting from the penetrating percutaneous foreign bodies almost always arise in the early post injury period. Delayed presentations of previous asymptomatic foreign bodies are rare. In this case report, symptoms of tracheal irritation arose seven years following the initial penetrating shrapnel injury to the neck. Computed tomography scans enabled localisation of the foreign body at the tracheal wall and carotid sheath interface. The usefulness of this radiologic modality in the evaluation of the penetrating soft tissue injury is highlighted. A review of the phenomenon of the migrating and asymptomatic foreign body follows.

Matched MeSH terms: Metallurgy

Radiation-induced chromosomal aberrations among TENORM workers: amang- and ilmenite-processing workers of Malaysia

Kandar MZ, Bhari IB

Mutat Res, 1996 Apr 13;351(2):157-61.

PMID: 8622709

The usefulness of peripheral human lymphocytes as a bioindicator for ionizing radiation effect was tested in a survey of Malaysian workers in two industries producing technologically enhanced naturally occurring radioactive material (TENORM). Workers in amang processing plants who have been with the plant for an average of 12.9 years and who were exposed to radioactive dust showed significantly higher frequencies of chromosomal aberration compared to control and even ilmenite-processing workers. Such frequency was not significantly different between workers in ilmenite-processing plant and control. The differences in duration of employment, occupational hygiene, together with the difference in the percentage of 'old' and 'new' aberrations among the groups sampled were used to explain the high chromosomal aberration frequency among amang workers. The presence of significantly high chromosome damage (dicentrics and fragments) in workers who were chronically exposed to doses below 50 mSv per year or 20 mSv per year averaged over 5 years (ICRP, 1991) provided additional experimental data on the dose-effect relationship at these low-dose ranges. The results confirm the usefulness of using human lymphocytes as a bioindicator for chronic exposure to ionizing radiation and in cases where physical radiation detectors are not available.

Matched MeSH terms: Metallurgy*

Flexibility and hardness of dental stainless steel wrought wires used in Thailand

Benjakul P, Cheunarrom C, Ongthiemsak C

J Oral Sci, 2001 Mar;43(1):15-9.

PMID: 11383631

Stainless steel wrought wires used as clasp arms for removable partial dentures in Thailand were compared with those used in some other countries (in the as-received condition) in terms of flexibility, Vickers microhardness and composition. The results showed that there were significant differences (P< or =0.05) among the wires. A Japanese stainless steel wire (SK) was obviously different from the others. It had the lowest proportional limit and microhardness, but its flexibility was almost the same. The chemical composition of each wire was not greatly different. The wires were about 18-20 wt% chromium and 8-9 wt% nickel, except for the SK wire, which had about 12 wt% nickel.

Matched MeSH terms: Metallurgy

Sorption of Cr(VI), Cu(II) and Pb(II) by growing and non-growing cells of a bacterial consortium

Sannasi P, Kader J, Ismail BS, Salmijah S

Bioresour Technol, 2006 Mar;97(5):740-7.

PMID: 16324841

This paper reports the sorption of three metallic ions, namely Cr(VI), Cu(II) and Pb(II) in aqueous solution by a consortium culture (CC) comprising an acclimatised mixed bacterial culture collected from point and non-point sources. Metal sorption capability of growing and non-growing cells at initial pH of between 3 and 8 in the 1-100mg/L concentration range were studied based on Q(max) and K(f) values of the Langmuir and linearised Freundlich isotherm models, respectively. Maximal metal loading was generally observed to be dependent on the initial pH. Growing cells displayed significant maximal loading (Q(max)) for Pb(II) (238.09 mg/g) and Cu(II) (178.87 mg/g) at pH 6 and at pH 7 for Cr(VI) (90.91 mg/g) compared to non-growing cells (p < 0.05). At the pH range of 6-8, growing cells showed higher loading capacity compared to non-growing cells i.e. 38-52% for Cr, 17-28% for Cu and 3-17% for Pb. At lower metal concentrations and at more acidic pH (3-4) however, non-growing cells had higher metal loading capacity than growing cells. The metal sorption capacity for both populations were as follows: Pb(II) > Cu(II) > Cr(VI).

Matched MeSH terms: Metallurgy*

Fulltext Study of anodised PM aluminium matrix composite reinforced with 15 wt % saffil™ alumina short fibre

Mohd Nazree Derman, Zainal Arifin Ahmad, Hussain, Luay Bakir, Nurulakmal Mohd Sharif

Journal of Nuclear and Related Technologies, 2007;2007(1):155-158.

MyJurnal

A study of wear behaviour on anodised PM aluminium matrix composites (AMC) reinforced with Saffil™ alumina short fibres was done. AMC was fabricated by powder metallurgy methods (PM) with using Al flake powders and Saffil™ alumina short fibres. AMC reinforced with 15 wt % Saffil¥ alumina short fibre was selected because it showed optimum mechanical and physical properties. Sulphuric acid anodising process was performed and the objective is to obtain suitable parameters of sulphuric acid concentration, anodising voltage and anodising time on MMC. The study of anodising process was carried out with various sulphuric acid concentrations (from 0 to 20 % volume), anodising voltage (10 V to 20 V) and anodising time (from 0 to 60 minutes) at room temperature. Scanning electron microscope (SEM) was used to investigate coating morphology and thickness. From the research, anodising voltage of 18 V and 15 % vol H2SO4 in anodising time of 60 minutes were suitable parameters for sulphuric acid anodising of this AMC. SEM showed the coating thickness around 20 Pm. From the reserch, it was found that H2SO4 anodising was able to give good coating to MMC.

Matched MeSH terms: Metallurgy

Fulltext Production of titanium carbide by thermal explosion and TiC/Ti functionally graded materials (FGMS)

Rahbari, R., Hamdi, M., Farhudi, O., Yahya, R., Asmalina, M., Marzuki, Z.

Journal of Nuclear and Related Technologies, 2007;2007(1):233-242.

MyJurnal

Self-propagating high-temperature synthesis (SHS) of powder compacts is a novel processing technique being developed as a route for the production of engineering ceramics and other advanced materials. The process, which is also referred to as combustion synthesis, provides energy- and cost-saving advantages over the more conventional processing routes for these materials. In the case of titanium or titanium alloy materials, prior researches employed powder metallurgy technology for preparing metal matrix composites, MMCs and laminated structures through the use of fine powders of an inert phase or phases (TiC, TiN, TiB and TiB2B ) dispersed in Ti or Ti alloy powders. The present research relates to manufacture of titanium-ceramic composites that are synthesized by combustion synthesis (SHS) and retains a multilayered composite microstructure comprising one or more titanium-based layers and one ceramic titanium carbide layers.

Matched MeSH terms: Metallurgy

Fulltext A study of microstructure and hardness on Fe-Co/SiC composites

Noraziana Parimin, Linus, Andy

Journal of Nuclear and Related Technologies, 2009;2009(1):65-70.

MyJurnal

This research was conducted to study the effect of reinforcement particles on iron-cobalt (FeCo) composites. The composition of silicon carbide (SiC) was varied from 0 to 20 wt%. The composite was fabricated via powder metallurgy (PM) method, which consists of mixing, compaction and sintering processes. The powder was mixed for 2 hours to obtain uniformity between SiC and Fe-Co matrix and compacted to a cylindrical shape at 250 MPa. Samples were sintered for 2 hours at 900 o C with 10 o C/minute heating rate in argon atmosphere. The influences of reinforcement particle on the sintered samples were characterized in terms of microstructure and hardness testing. The Fe-Co/20wt%SiC composites show highest hardness value.

Matched MeSH terms: Metallurgy

Fulltext Fabrication and characterisation of aluminium boron carbide composites for neutron shielding

Yusof Abdullah, Mohd Reusmaazran Yusof, Nadira Kamarudin, Paulus, Wilfred Sylvester, Rusnah Mustaffa, Nurazila Mat Zali, et al.

Jurnal Sains Nuklear Malaysia, 2012;24(1):71-80.

MyJurnal

Al/B4C composites with 0 wt.%, 5 wt.% and 10 wt.% of B4C were prepared by powder metallurgy and their properties were characterised successfully. Investigation of the effect of milling times (4, 8, 12, 16 hours) on microstructure, phase identification, hardness and neutron attenuation coefficient of composites has been studied. The results showed that hardness increased with increased of milling time, with maximum hardness obtained at 16 hours milling time. The increment is slower as the composition of B4C increased. The hardness of Al/10%B4C, Al/5%B4C and Al/0%B4C were 81.7, 78.7 and 61.2 HRB respectively. Morphology of scanning electron microscopy (SEM) showed that microstructures play important role in controlling the hardness. Meanwhile, x-ray diffraction (XRD) analysis showed the phases and crystalline present in composites with an indication that crystalline of the grain increased as the milling time increased. Neutron absorption of Al/10%B4C composites showed that this composite has the highest attenuation coefficient, thus indicating that it is the best composites for neutron shielding.

Matched MeSH terms: Metallurgy

Fulltext Al/b4c composites with 5 and 10 wt% reinforcement content prepared by powder metallurgy

Yusof Abdullah, Mohd Reusmaazran Yusof, Azali Muhammad, Nadira Kamarudin, Paulus, Wilfred Sylvester, Nurazila Mat Zali, et al.

Journal of Nuclear and Related Technologies, 2012;2012(1):42-47.

MyJurnal

The preparation, physical and mechanical properties of Al/B4C composites with 5 and 10 wt.% reinforcement content were investigated. In order to obtain the feedstock with a low powder loading, B4C mixtures containing fine powders were investigated to obtain the optimal particle packing. The experimental results indicated that the fine containing 5 and 10 wt.% particles are able to prepare the feedstock with a good flowability. The composites fabricated by powder metallurgy have low densities and homogeneous microstructures. Additionally there is no interface reaction observed between the reinforcement and matrix by XRD analysis. The hardness of Al/B4C composites prepared by powder metallurgy was high.

Matched MeSH terms: Metallurgy

Fulltext Semisolid metal processing techniques for nondendritic feedstock production

Mohammed MN, Omar MZ, Salleh MS, Alhawari KS, Kapranos P

ScientificWorldJournal, 2013;2013:752175.

PMID: 24194689 DOI: 10.1155/2013/752175

Semisolid metal (SSM) processing or thixoforming is widely known as a technology that involves the formation of metal alloys between solidus and liquidus temperatures. For the procedure to operate successfully, the microstructure of the starting material must consist of solid near-globular grains surrounded by a liquid matrix and a wide solidus-to-liquidus transition area. Currently, this process is industrially successful, generating a variety of products with high quality parts in various industrial sectors. Throughout the years since its inception, a number of technologies to produce the appropriate globular microstructure have been developed and applied worldwide. The main aim of this paper is to classify the presently available SSM technologies and present a comprehensive review of the potential mechanisms that lead to microstructural alterations during the preparation of feedstock materials for SSM processing.

Matched MeSH terms: Metallurgy/methods*

Fulltext The influence of depassivating element on the performance of aluminium anodes

Daud, M., Mohd Kamarudin, S.R., Samsu, Z., Ripin, M.S., Sattar, M.S., Rejab, R.

Journal of Nuclear and Related Technologies, 2013;2013(2):16-20.

MyJurnal

The corrosion behaviour of ternary aluminium alloy sacrificial anodes with small amount addition of tin as depassivating element in natural seawater was studied by means of conventional DC electrochemical measurements. Metallurgical microscope was employed in order to observe the changing of microstructure caused by tin present in ternary alloys. The relationship between microstructure and electrochemical results was examined and particular attention paid to the cause of the electrochemical efficiency of anode performance. The results indicate that the proper precipitates uniformly distributed of tin are influence on improving electrochemical performance of alumnium alloy anode.

Matched MeSH terms: Metallurgy

Fulltext An alternate method to springback compensation for sheet metal forming

Siswanto WA, Anggono AD, Omar B, Jusoff K

ScientificWorldJournal, 2014;2014:301271.

PMID: 25165738 DOI: 10.1155/2014/301271

The aim of this work is to improve the accuracy of cold stamping product by accommodating springback. This is a numerical approach to improve the accuracy of springback analysis and die compensation process combining the displacement adjustment (DA) method and the spring forward (SF) algorithm. This alternate hybrid method (HM) is conducted by firstly employing DA method followed by the SF method instead of either DA or SF method individually. The springback shape and the target part are used to optimize the die surfaces compensating springback. The hybrid method (HM) algorithm has been coded in Fortran and tested in two- and three-dimensional models. By implementing the HM, the springback error can be decreased and the dimensional deviation falls in the predefined tolerance range.

Matched MeSH terms: Metallurgy/methods*

Fulltext Palm oil derived trimethylolpropane triesters synthetic lubricants and usage in industrial metalworking fluid

Chang TS, Yunus R, Rashid U, Choong TS, Awang Biak DR, Syam AM

J Oleo Sci, 2015;64(2):143-51.

PMID: 25748374 DOI: 10.5650/jos.ess14162

Trimethylolpropane triesters are biodegradable synthetic lubricant base oil alternative to mineral oils, polyalphaolefins and diesters. These oils can be produced from trimethylolpropane (TMP) and fatty acid methyl esters via chemical or enzymatic catalyzed synthesis methods. In the present study, a commercial palm oil derived winter grade biodiesel (ME18) was evaluated as a viable and sustainable methyl ester source for the synthesis of high oleic trimethylolpropane triesters (HO-TMPTE). ME18 has fatty acid profile containing 86.8% oleic acid, 8.7% linoleic acid with the remaining minor concentration of palmitic acid, stearic acid and linolenic acid. It's high oleic property makes it superior to produce synthetic lubricant base oil that fulfills both the good low temperature property as well as good oxidative stability. The synthetic base oil produced had a viscosity of 44.3 mm(2)/s at 40°C meeting the needs for ISO 46 oils. It also exhibited an excellent viscosity index of 219 that is higher than some other commercial brands of trimethylolpropane trioleate. Properties of base oil such as cloud point, density, acid value, demulsibility and soap content were also examined. The oil was then used in the formulation of tapping oil and appraised in term of adaptability, stability and field test performance.

Matched MeSH terms: Metallurgy*

Fulltext Nanomechanical Behavior of Multi-Walled Carbon Nanotubes Particulate Reinforced Aluminum Nanocomposites Prepared by Ball Milling

Ostovan F, Matori KA, Toozandehjani M, Oskoueian A, Yusoff HM, Yunus R, et al.

Materials (Basel), 2016 Feb 26;9(3).

PMID: 28773261 DOI: 10.3390/ma9030140

The nanomechanical properties of carbon nanotubes particulate-reinforced aluminum matrix nanocomposites (Al-CNTs) have been characterized using nanoindentation. Bulk nanocomposite specimens containing 2 wt % multiwalled CNTs (MWCNTs) were synthesized by a combination of ball milling and powder metallurgy route. It has been tried to understand the correlation between microstructural evolution particularly carbon nanotubes (CNTs) dispersion during milling and mechanical properties of Al-2 wt % nanocomposites. Maximum enhancement of +23% and +44% has been found in Young's modulus and hardness respectively, owing to well homogenous dispersion of CNTs within the aluminum matrix at longer milling time.

Matched MeSH terms: Metallurgy

Fulltext Fabrication and Compressive Properties of Low to Medium Porosity Closed-Cell Porous Aluminum Using PMMA Space Holder Technique

Jamal NA, Tan AW, Yusof F, Katsuyoshi K, Hisashi I, Singh S, et al.

Materials (Basel), 2016 Mar 30;9(4).

PMID: 28773377 DOI: 10.3390/ma9040254

In recent years, closed-cell porous Aluminum (Al) has drawn increasing attention, particularly in the applications requiring reduced weight and energy absorption capability such as in the automotive and aerospace industries. In the present work, porous Al with closed-cell structure was successfully fabricated by powder metallurgy technique using PMMA as a space holder. The effects of the amount of PMMA powder on the porosity, density, microstructure and compressive behaviors of the porous specimens were systematically evaluated. The results showed that closed-cell porous Al having different porosities (12%-32%) and densities (1.6478 g/cm³, 1.5125 g/cm³ and 1.305 g/cm³) could be produced by varying the amount of PMMA (20-30 wt %). Meanwhile, the compressive behavior results demonstrated that the plateau stress decreased and the energy absorption capacity increased with increasing amount of PMMA. However, the maximum energy absorption capacity was achieved in the closed-cell porous Al with the addition of 25 wt % PMMA. Therefore, fabrication of closed-cell porous Al using 25 wt % PMMA is considered as the optimal condition in the present study since the resultant closed-cell porous Al possessed good combinations of porosity, density and plateau stress, as well as energy absorption capacity.

Matched MeSH terms: Metallurgy

Fulltext Metal dust exposure and lung function deterioration among steel workers: an exposure-response relationship

Hamzah NA, Mohd Tamrin SB, Ismail NH

Int J Occup Environ Health, 2016 07;22(3):224-232.

PMID: 27392157 DOI: 10.1080/10773525.2016.1207040

BACKGROUND: Metallic dust is a heterogeneous substance with respiratory sensitizing properties. Its long term exposure adversely affected lung function, thus may cause acute or chronic respiratory diseases.

METHODS: A cross-sectional study was conducted in a steel factory in Terengganu, Malaysia to assess the metal dust exposure and its relationship to lung function values among 184 workers. Metal dust concentrations values (Co, Cr, and Ni) for each worker were collected using air personal sampling. Lung function values (FEV1, FVC, and %FEV1/FVC) were determined using spirometer.

RESULTS: Exposure to cobalt and chromium were 1-3 times higher than permissible exposure limit (PEL) while nickel was not exceeding the PEL. Cumulative of chromium was the predictor to all lung function values (FEV1, FVC, and %FEV1/FVC). Frequency of using mask was positively associated with FVC (Adj b = 0.263, P = 0.011) while past respiratory illnesses were negatively associated with %FEV1/FVC (Adj b = -1.452, P = 0.026). Only few workers (36.4%) were found to wear their masks all times during the working hours.

CONCLUSIONS: There was an exposure-response relationship of cumulative metal dust exposure with the deterioration of lung function values. Improvement of control measures as well as proper and efficient use or personal protection equipment while at work could help to protect the respiratory health of workers.

Matched MeSH terms: Metallurgy

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