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1

Treatment of effluent (skim latex serum) from a rubber processing plant with Fenton’s reagent

Lim Y. P., El-Harbawi M., Yin C.

Environment Protection Engineering

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2017

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Vol. 43, nr 3

247--254

EN

The treatment effectiveness of Fenton's reagent using Fe2+catalyst to reduce chemical oxygen demand (COD) of skim latex serum and the effect of varying concentrations of H2O2, Fe2+and initial solution pH on its treatment efficiency were investigated. The highest COD removal efficiency obtained was approximately 80% at optimum conditions. The treatment required either nominal or no acidification as initial pH of serum is very close to the optimum pH = 4. COD removal increased upon increasing H2O2 and Fe2+concentrations. This study shows the suitability of using Fenton's process with H2O2and FeCh as a pre-Treatment for skim latex serum. The findings reported here represent a potentially simpler and more cost-effective alternative treatment to other treatment methods since only reagents and not capital-intensive materials (such as membrane) are required.

2

Microstructural and mechanical properties of gravity-die-cast A356 alloy inoculated with yttrium and Al-Ti-B grain refiner simultaneously

Lim Y. P., Ooi J. B., Wang X.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 4

77-82

EN

In the present work, the effect of inoculating yttrium and Al-5Ti-1B simultaneously on A356 aluminum alloy has been studied. Gravity die casting process is used to cast the ASTM tensile test specimens for analysis. In each experiment, the Ti and B contents were maintained constantly at 0.1 and 0.02 wt% respectively. The addition of yttrium was manipulated at the amount of 0, 0.1, 0.2, 0.3, 0.4 and 0.5 wt%. Microstructural characterization of the as-cast A356 alloy was investigated by means of optical microscope and its phases are detected by XRD. The mechanical properties tested are tensile strength and hardness. The inoculation of yttrium was found to enhance the grain refinement effect of Al-5Ti-1B grain refiner and improve the mechanical properties. The optimal weight percentage of yttrium was found to be 0.3. The grain refining efficiency of combining yttrium and Al-5Ti-1B on A356 aluminum alloy was mainly attributed to the heterogeneous nucleation of TiB2 and TiAl3 particles which were dispersed more evenly in the presence of yttrium and the grain growth restriction effected by the accumulation of Al-Y compound at grain boundaries.

3

Grain refinement and heat treatment of gravity die cast A356

Lim Y. P.

Archives of Foundry Engineering

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2010

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Vol. 10, iss. 4

103--108

EN

The purpose of this investigation is to evaluate the effects of grain refiner TiCal315 (3%Ti, 0.15% C) and Al-5Ti-1B on the metallurgical properties of as-cast A356 gravity die castings as well as the improvement brought about by T6 heat treatment. The TiCal315 and Al-5Ti- 1B grain refiners were added separately into the A356 melt in different weight percentages of 0.25, 0.5, 0.75 and 1.0 to produce the gravity die casting samples. The geometry of the casting is designed to be cylindrical shape according to JIS H5202. The results show that TiCal315 is relatively more effective than Al-5Ti-1B to improve the tensile strength, hardness and elongation of A356 alloy by 10~20%. T6 heat treatment is confirmed to have more significantly improved the mechanical properties of A356 alloy compared to grain refinement. An Olympus imaging software was used to measure the average grain size of α-Al phase and the results do not show significant difference between TiCal315 and Al-5Ti-1B to grain-refine the A356 dendritic structures. The morphology of T6 heat treated A356 was changed where the irregular eutectic was converted into spherodized Si particles due to the solution treatment. This results in significant improvement in mechanical properties.

4

Evaluation of Al-5Ti-1B and Al-10Sr in LM6 sand castings

Lim Y. P.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 34, nr 1

71-78

EN

Purpose: of this paper is to study the separate effects of grain refiner and modifier on the metallurgical properties of LM6 sand castings. The research aims to determine how grain refiner and modifier will influence the microstructure of LM6 sand casting and the associated mechanical properties of hardness, ultimate tensile strength and engineering strain. Design/methodology/approach: A grain refiner consists of 0.5wt% Al-5Ti-1B and a modifier consists of 0.5wt% Al-10Sr have been introduced separately into the melt of hypoeutectic LM6 Al-Si alloy to produce slab castings by CO2 sand casting process. The geometry of the slab casting is designed to have different section moduli to induce directional solidification. Temperature profile of cooling process is taken to correlate between the section modulus and cooling rate. This enables the effect of cooling rate on microstructure and mechanical properties to be studied for grain refined and modified LM6 sand castings. Findings: The significant finding is that a nearly full eutectic solidification at 540°C is achieved in the Sr-modified casting with faster cooling rates than those of solely grain-refined and original LM6. The hardness and ultimate tensile strength can be improved respectively between 20~40% and 11~18% by Al-10Sr modifier. It is observed that the Al-5Ti-1B grain refiner and Al-10Sr modifier increase the strain at UTS by 11% and 22% respectively. The metallographic observations show that the eutectic phase is finer and in fibrous form in the Sr-modified LM6. Research limitations/implications: Further research can study a wider range of inoculant percentage. Practical implications: This eutectic solidification at 540°C achieved in Sr-modified LM6 is lower than the solidus temperature of LM6 to reduce superheat and save electrical energy consumption while ensuring complete liquid mould filling. Originality/value: This is the original work of slab casting of LM6 and the effects of Sr modifier and TiB grain refiner on its metallurgical properties.