Materials Science Forum Vols. 620-622

Abstract: The low yield of ITO thin film deposition is an important factor in optoelectronic semiconductor production. A recycle fabrication module uses micro electroremoving as a precision machining process with a new design of inner wedge-form tool to remove the defective Indium-tin-oxide (ITO) nanostructure from the optical PET surfaces of digital paper display is presented in current studies. The adopted precision recycle process requires only a short period of time to remove the ITO nanostructure easily and cleanly is based on technical and economical considerations and is highly efficient. In the current experiment, a higher feed rate of the optical PET diaphragm combines with enough electric power to drive fast micro electroremoving. A large slant angle of the cathode and a small arc rounding radius of the anode takes less time for the same amount of ITO removal. High rotational speed of the electrodes can improve the effect of dregs discharge and is advantageous to associate with the fast feed rate of the workpiece (optical PET diaphragm). A small rotational diameter of the anode accompanied by a small width of the cathode corresponds to a higher removal rate for the ITO nanostructure.

Abstract: Removal of Zn (II) from aqueous solution by copolymer of grafting acrylic acid onto deacetylated konjac glucomannan (GADKGM) was evaluated in a bath adsorption system. Operational parameters such as pH, time, temperature and initial concentration were studied in present work. The adsorption process was relatively fast and highly effective. Removal efficiency for Zn(II) solution at the concentration of 100 mg/L was 98% at optimum operational pH of 6. The removal rate for Zn(II) on GADKGM was very fast and the removal efficiency can attain about 90% within 5 min. Isotherm adsorption data were described by Langmuir model with monolayer adsorption capacity of 125 mg/g. The negative values of thermodynamic parameters of △Go and △So indicated that adsorption process was a spontaneous process and randomness at the solid/liquid interface was decreased during the adsorption process.

Abstract: CaO addition to Mg forms the Al2Ca and Mg2Ca phases without solid solution even below solubility limit. In this study, thermodynamic considerations of CaO added Mg alloys in recycling process are investigated in comparison with Ca added Mg alloys. Thermodynamic considerations were done by using the army-navy-air force (JANAF) thermochemical tables between Ca or CaO added Mg alloys and fluxes such as MgCl2, KCl, NaCl and MnCl2. The mechanisms during recycling process were thermodynamically discussed. Actual recycling experiments were also carried out to compare the thermodynamic results.

Abstract: The effect of two kinds of mineral admixtures (MA) on volume stability of steel slag mortar (SSM) is investigated in order to solve the expansion problem due to steel slag. The rate of linear expansion and flexural strength of SSM containing mineral admixture have been compared with control specimens. Addition of FA and GGBFS slowed down the rate of expansion gain and prolonged the stable ages of SSM. In addition, FA and GGBFS increased later flexural strength of SSM. The improving effect of FA and GGBFS on volume stability of SSM was attributed to the increase of later flexural strength and enhancement of compaction rate.

Abstract: In this study, mine tailings obtained in a region near to Youngwol Sangdong(Korea) was used to investigate the contamination of heavy metal ions. Some amount of mine tailings and lignin(AE agent) were added in the general cement pastes, of which the compressive strength and leaching rate were investigated. X-ray fluorescence analysis shows that the major constituents of mine tailings are 56.9wt% of SiO2, 10.8wt% of Fe2O3, 11.2wt% of CaO and 11.4wt% of Al2O3, and the major phases are quartz and calcite. In the content of heavy metal ions, the concentration of As ion is the highest as 257.261mg/ℓ. When mine tailings and lignin were added in cement pastes, the compressive strength was higher in the cement pastes adding only lignin. Lignin addition significantly improved the compressive strength of cement pastes by approximately 15% when being cured in distilled water. The compressive strength was lower in the cement pastes adding mine tailings than in the cement pastes not adding. The leaching rates of Cr, Pb and As ion in distilled water were decreased in the cement pastes adding lignin, compared to in the cement pastes not adding. The leaching rates of all heavy metal ions in the cement pastes curing for 28 days were within the maximum permitted limits in KSLT and EPT method. Therefore, it is thought that mine tailings can be used as an ecological material.

Abstract: Konjac Glucomannan (KGM) was modified by maleic anhydride (MA). The influences of processing parameters on the mechanical properties of KGM films were investigated through orthogonal experiments. The results showed that the effects of pH, temperature and time of KGM swelling on tensile strength and folding endurance of modified KGM membranes were insignificant (FF0.01). Folding endurance and tensile strength of KGM membranes could be improved by proper addition of MA. The optimum conditions of KGM modification were that the mixture of KGM and MA was swelling at pH 4.0 and 60°C for 2 h, and then cast on a flat and dried at 50°C to give modified KGM membranes.

Abstract: In this work, inorganic paste was made from melting slag (MS) of MSWI ash and MSWI bottom ash (MBA) by geopolymer technique. Heavy metals such as Pb and Cu are highly contained in MBA. In the view of environmental protection and resource conservation, recycling of MSWI ash is desirable. MS and MBA were mixed to make inorganic paste. Compressive strength was measured to evaluate the characteristics of inorganic paste after the period of 1, 3 and 7day. Compressive strength of almost 90 MPa was obtained at the mixing ratio of MS : MBA = 9 : 1. And the crystalloid and crystal structure was analyzed by FTIR and XRD. Korea Standard leaching Test (KSLT) is also used to evaluate the environmental safety of inorganic paste. The leached concentration of Pb and Cu were 0.44 ppm and 0.15 ppm, respectively. According to this result, heavy metals were safety immobilized and stabilized.

Abstract: Calcium slag (CS) is a by-product generated during smelting to extract calcium metal from the ore by aluminothermic reduction method. The melting point, melting speed, viscosities, surface tensions and the refining effects of CS and normal premelted refining slag (NPRS) were measured in the laboratory. Then the plant trials were done in a 150 tons Ladle Furnace (LF) in a steelmaking plant during the refining of clean steel. The results show that the properties of CS are similar to those of NPRS, and CS is a good refining agent not only in laboratory experiment but also in industrial production. By using CS, the average final sulfur content in X70 pipeline steel reaches 25×10-6; the total oxygen content in GCr15 bearing steel is 5×10-6~8×10-6; the titanium content in GCr15 bearing steel is less than 20×10-6 and lower than the steels refined by using NPRS.

Abstract: The objective of this research was to make brick from waste materials, such as MSWI fly ash, water sludge and coffee sludge. It was made by mixing raw materials, drying at room temperature for 24 hrs, and at 60°C ~ 100°C for 1hrs. The dried bricks sintered to 1100 ~ 1150°C by 5°C/min and then kept at that temperature for 2hrs. Compressive strength, water absorption were measured to discuss the characteristics of brick prepared. Toxicity characteristic leaching procedure(TCLP) test is also used to evaluate the environmental safety. The optimum condition was obtained at the mixing ratio as followed; 20:19.5:0.5:60 of MSWI fly ash, water sludge, coffee sludge and clay. Considering the value of compressive strength and water adsorption for prepared brick, it can be used as an alternative brick.

Abstract: This paper describes a method of removing phosphate (P) from aqueous solution by sorbent prepared with amorphous blast furnace slag (BFS) and hydrated lime. An orthogonal experiment was carried out to investigate the factors of hydration time, slurrying temperature and the weight ratio of blast furnace slag /hydrated lime and water/solid on the reactivity of the sorbent. Chemical composition of BFS was analyzed by atomic absorption spectrometry, microstructure and phase analysis of samples were conducted by SEM and XRD. It is found that all sorbents prepared show higher P adsorption capacity than single blast furnace slag.