Nation Metal and Materials Technology Center

Pathum Thani, Thailand

Nation Metal and Materials Technology Center

Pathum Thani, Thailand

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Lamlerttham J.,King Mongkut's University of Technology Thonburi | Wila P.,Nation Metal and Materials Technology Center | Morakotjinda M.,Nation Metal and Materials Technology Center | Krataitong R.,Nation Metal and Materials Technology Center | And 4 more authors.
Key Engineering Materials | Year: 2013

Tungsten is a promising refractory metal suitable for applications in which wear resistance, thermal stability and high weight are needed. In this work, the tungsten feedstock (94wt%W with balance of Ni-Cu-Co alloy) was used to form tensile test specimens by using metal injection molding (MIM) process. The molded specimens were debinded by catalytic debinding technique to convert to the brown specimens. After debinding, the brown parts were sintered under vacuum atmosphere (10-5 bar) with varied sintering times at sintering temperature from 1350 to 1450°C. The specimens sintered at 1450°C for 3 hours provided optimum sintered density and mechanical properties. The results showed that mechanical properties of the specimens sintered at 1450°C dramatically decreased when sintering times were longer than 3 hours. The specimens sintered at 1450°C for 8 hours showed brittleness. Physically, inferior mechanical properties were attributed to wettability and porosity of the binder phase. Chemical analyses were performed with the sintered W-(Ni-Cu-Co) specimens by using energy dispersive spectroscopy with mode of quantitative analysis. The specimens sintered at 1400°C for 3 hours showed high W content (28.95 wt. %) dissolved in the Ni-Cu-Co binder. However, penetration of the liquid binder was incomplete. The specimens sintered at 1450°C for 3 hours showed higher W content (34.28 wt. %) dissolved in the Ni-Cu-Co binder (with lower Cu content). Distribution of Cu was uniform across the whole specimen. Wetting of the liquid binder on W grains was complete without porosity. The specimens sintered at 1450°C for longer than 3 hours showed less W content (< 28.95 wt. %) dissolved in the Cu-depleted Ni-Co binder. Porosity was observed in the binder phase and in W grains. Sintering between W grains was also observed. Effects of different sintering atmospheres were also investigated. It was found that increasing the sintering chamber pressure caused detrimental effects on both physical and mechanical properties of the sintered tungsten specimens. In addition, nitrogen atmosphere gave similar results to those for increased chamber pressure. © (2013) Trans Tech Publications.


Niranatlumpong P.,Nation Metal and Materials Technology Center | Sukhonket C.,Nation Metal and Materials Technology Center | Nakngoenthong J.,Nation Metal and Materials Technology Center
Wear | Year: 2013

The pulverizer blade in food and animal feed production is subjected to abrasive wear from agricultural produce such as millet, corn, beans, rice husk and hull, resulting in the contamination of food by the wear debris from the blade material. This work compares different surface treatment and coating techniques used in improving the abrasive wear resistance of the blade, thus reducing the amount of contaminant. Four types of pulverizing blades were tested, namely flame hardened blade, hard Cr plated blade, plasma-sprayed Al2O3-TiO2 coated blade and HVOF-sprayed WC-Co coated blade. The dry abrasive wear test was carried out in a lab scale pulverizing test rig using rice husk as the abrasive media. The wear result, reported as the reduced area of the leading face, shows that the hard Cr plated-, Al2O3-TiO2 coated- and WC-Co coated blades display similar wear rates, which is lower than that of the flame hardened blade. When the weight loss of the blade was calculated from the wear volume and density of each blade, it was found that the Al2O3-TiO2 coated blade exhibits significantly lower weight loss due to its low density, rendering a lower mass of contaminant being released into the produce. The weight losses of the blades fitted in the inside position after 40h of pulverizing test are 8.4, 3.7, 1.6 and 4.8mg per one blade for flame hardened blade, hard Cr plated blade, Al2O3-TiO2 coated blade and WC-Co coated blade, respectively. These values were used to estimate the contaminant concentrations in rice husk. © 2012 Elsevier B.V.


Shivaraju H.P.,University of Mysore | Byrappa K.,University of Mysore | Shayan M.B.,SCJC | Rungnapa T.,Nation Metal and Materials Technology Center | And 3 more authors.
Materials Research Innovations | Year: 2010

Hydrothermal coating of ZnO nanoparticles onto the surface of calcium alumino silicate beads was carried out under hydrothermal conditions (T, 220°C; P, 300 psi; duration, 12 h). The reagent grade ZnO and calcium alumino silicate beads (0•5-1•0 mm in diameter, specially prepared as supporting material for ZnO) were used as starting materials along with 1M NaOH as a mineraliser leading to the formation of a new class of photocatalytic material. The effect of the hydrothermal experimental parameters on the coating of ZnO nanoparticles, and the grain morphology, etc. was investigated and thus obtained ZnO coated calcium alumino silicate beads were characterised using X-ray diffraction, SEM, Fourier transform infrared and positron annihilation spectroscopy. Sunlight and ultraviolet light mediated photocatalytic degradation of amaranth dye was studied using hydrothermally prepared ZnO coated calcium alumino silicate beads. The effect of various parameters such as initial dye concentration, catalytic loading, pH of the medium, time duration and light source on the photodegradation of amaranth dye was investigated. Silk industrial effluents containing amaranth dye as a major constituent along with other dyes and dyeing auxiliaries were treated using ZnO coated calcium alumino silicate beads. © 2010 W. S. Maney & Son Ltd.


Shivaraju H.P.,University of Mysore | Sajan C.P.,University of Mysore | Rungnapa T.,Nation Metal and Materials Technology Center | Kumar V.,Tokyo Metroplitan University | And 2 more authors.
Materials Research Innovations | Year: 2010

The hydrothermal synthesis of TiO 2 nanoparticles on the surface of calcium aluminosilicate beads of 0•5-1•0 mm in diameter has been carried out under mild hydrothermal conditions. The advantage of immobilisation of the TiO 2 nanoparticles by coating on calcium aluminosilicate beads is the ease and efficiency to recover the photocatalyst. The experimental temperature was varied from 150 to 220°C and the experimental duration was 24 h with an autogenous pressure in 1M HCl as solvent. A systematic characterisation of TiO 2 coated calcium aluminosilicate beads was carried out by employing analytical techniques like X-ray powder diffraction, SEM, FTIR spectroscopy and positron annihilation lifetime spectroscopy. The photocatalytic treatment of toxic organic pollutants in textile effluents was studied using hydrothermally prepared TiO 2 coated calcium aluminosilicate beads. The photodegradation characteristics were studied under both sunlight and ultraviolet light source on the degradation of organic pollutants. Several parameters like concentration and dilution factors of effluents, light source and intensity, initial pH of medium, experimental duration and catalyst loaded into the aqueous medium of textile effluent were studied. The degradation reaction was optimised with respect to the experimental duration and catalytic loaded. The reduction in the chemical oxygen demand (COD) and %T revealed the minimisation of organic pollutants along with colour removal from the textile effluent. © 2010 W. S. Maney & Son Ltd.

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