Applied Mechanics and Materials Vols. 754-755

Abstract: A doubled-sided lapping machine of grinding stone manufactured of a SiC as an abrasive, specific resin and other thermosetting resin were developed for grinding process of the substrate of hard disk drive (HDD) made up of aluminum since the conventional lapping machine cause the serious quality problem of the magnetic substrate. However, at certain parameter during the grinding process, the abrasive stone was clogging due to the agglomeration of debris from the substrate which cause scratches on the magnetic substrates and affect its performance. The samples were classified into four parts (soft spot, border spot, hard spot, and unused spot). Characterizations of the samples were done using XRF, SEM and FTIR analysis. Based on all the above analysis, it can conclude that the porosity of the stone were not homogeneous and the percentage of Al was highest at the border spot which shows that, the area at the border spot cause the clogging to occur thus produces the hard spot that will damage the magnetic substrate during grinding process.

Abstract: The use of recycled natural latex rubber glove (NRL-G) as a reinforced material filled acrylonitrile butadiene rubber (NBR) was studied. The compounds of different NRL-G loading (0, 10, 20 and 30 phr) were prepared by using two roll mills at room temperature. Two different size ranges of NRL-G such as 300μm-700μm (fine) and 2cm-4cm (coarser) were used. The properties such as cure characteristics, tensile and physical properties were determined. The NBR/NRL-G compound with the fine size of NRL-G exhibits overall good cure characteristics and physical properties compared with coarser size. The addition of the of 20 phr content NRL-G (fine) contributed to the optimum tensile properties than coarser size.

Abstract: Geopolymer ceramic have been produced by the powder metallurgy (PM) technique. The samples were reacted by the alkaline activator to activate the geopolymerization process and crushed by using Mortar and Pestle to powderized the samples. Powder metallurgy technique was used and samples were heated at different temperature start from 700 °C until 1200°C and the strength were tested. The relative density and flexural strength of sintered sample ranged approximately 84%-95% and 20-100 MPa respectively. Microstructural properties was conducted by scanning electron microscopic (SEM) and the surface analysis by energy dispersive X-ray (EDX).

Abstract: This paper presents the study of the thermal degradation of a wood painting support from the "Saints Constantine and Helen” church. As a cultural heritage monument, the iconostasis of the church has an artistic and historic value. In time it suffered a great deal from earthquakes, floods, wars and fire. In the XXth century a large fire burned big parts of the iconostasis and the original painting needed to be replaced. Small pieces of the burned iconostasis are kept for study and restauration in specialised institutions. The aim of this study is to bring new information on thermal degradation and deterioration of old wood from panel paintings. In this regard non-invasive modern techniques were used for analysis, as Optical Microscopy (OM), Thermogravimetric Analysis (TGA) and Differential thermal analysis (DTA). The analysis were made on a small wood chip that was taken from the panel in the conservation process. The analysis concluded that the wood support was already degraded and deteriorated by biological attacks, which made the fire spread easier. The TGA and DTA concluded that there is a good correlation to the aging of lime wood with the complexity of thermogravimetric processes.

Abstract: Kaolin, an aluminosilicate source materials was mixed with alkaline activator solution to create a geopolmer paste which was coated on teak wood subsrates. In this work, the effect of solid/liquid ratio (0.4, 0.6, 0.8 and 1.0) was analysed while other parameters were maintained constant. Coating teak wood substrates via geopolymer technology was focused to see the enhancement made to the mechanical properties of teak wood. Various test such as adhesive strength test, water absorption and morphology study was conducted after seventh day of sample preparation. Kaolin coated sample with 1.0 solid/liquid ratio showed the highest adhesive strength of 10.5 MPa and the lowest water absorption of 6.3%. Morphology studies also supported the trend of promising compatibility between kaolin coating and teak wood substrate at 1.0 solid/liquid ratio which further evident the accuracy of collected data.

Abstract: The wooden sculptures in orthodox churches are usually gilded with golden leaves, applied by means of different techniques (with bole or mixtion). Silver leaf was also used for economic or aesthetic purposes, usually covered with coloured lakes: red, green (for flowers, leaves and fruits) or yellow (for gold imitation). This study presents analysis realized on samples of coloured lakes taken from different cult objects. We used red and green lakes taken from the royal doors of the St. Nicholas church from Aroneanu, Iasi (1814) and from the royal doors and deacon doors from St. Archangels Church, Ceplenita, Iasi (beginning of the 19th century). The yellow samples were taken from two icons painted in russian style: St. Nicholas and Holy Virgin of Kazan (beginning of 19th century). The SEM-EDX and FT-IR spectra revealed the different origins of the lake (organic and inorganic) and suggested the technique for their preparation.

Abstract: A study of water as the agent of functionalization is still new since most of researchers used acid as the agent of functionalization. The objective of this study is to investigate the used of water as a medium of functionalization of commercialized activated carbon in order to be used in removal of methylene blue dyes from synthetic wastewater via adsorption. The parameters for functionalization of the commercialized activated carbon included temperature at 35°C, contact time of 5 hours and various frequency at 100, 150 and 200 rpm. The experiment was conducted in a batch process where the commercialized activated carbon were functionalized under the mentioned parameters. The functionalized activated carbon were characterized using Fourier Transform Infra-Red (FTIR) Spectroscopy. The FTIR analysis indicated the increase of the amount of functional group attached to the activated carbon. The dye adsorption study was conducted by using methylene blue solution with initial concentration of 500 ppm as adsorbate and the functionalized activated carbon as adsorbent. A standard calibration curve for methylene blue solution was generated using of Ultraviolet-Visible (Uv-Vis) Spectrophotometer. The result from the adsorption study was the parameter of temperature at 35°C, contact time of 5 hours and varying water bath shaker frequency at 100 rpm yield the best adsorption rate.

Abstract: The purpose of this paper is to analyze the dimensional accuracy of the surfaces straight edges from cutting plasma free atmosphere or water bed. The aim was to identify any defects and if bed piss water cut in some way influence the surface quality and dimensional contours right. Mechanical thermal plasma cutting bed prevents overheating of the water has the advantage that the base material and thus the parameters related to compliance with the slag assures cut pieces at the bottom, this saves the cost of production. Mechanized plasma cutting bed heat the water does not affect the value of angle tolerance compared to cutting outdoor (angular deviation determined either for parts or cut outdoor water bed ranged between 7-9 degrees / side). The causes of and ways to reduce the deviation angle cut edge is determined by other factors such as cutting speed, distance torch-material, cutting nozzle erosion.

Abstract: The use of monocoagulants, such as Chitosan, may not be a good solution for highly turbid water purification because of its high cost. The possibility to reduce the amount of the primary coagulant at the same time keeping the removal to be in optimum may be a good strategy to reduce the operation cost. There might be another coagulant aid for example the natural clay of Bentonite to reduce the cost. The initial stage is to determine the Bentonite dosage and mixture ratio to be used with Chitosan. Coagulation of Chitosan-Bentonite had successfully removed the turbidity with the efficiency of 97%. The coagulants performed well when Chitosan-Bentonite ratio is 30:70 at concentration of 1000mg/l

Abstract: The effect of sintering temperature and Mn-Ti (x = 0.1 and 0.5 % mol) doped in Barium hexaferrite (BaFe₁₂O₁₉) on the microwave absorption properties have been investigated. The BaFe_(12-2x)Mn_xTi_xO₁₉ samples were prepared by using a solid state reaction method from technical grade materials of BaCO₃, Fe₂O₃, MnO₂, and TiO₂. The permagraph and vector network analyzer (VNA) measurement with frequency of 4 – 10 GHz were used to determine the magnetic properties and microwave absorbing properties, respectively. The magnetic induction and magnetizing force (B-H) curve analysis of BaFe_(12-2x)Mn_xTi_xO₁₉ revealed that by increasing the Mn-Ti dopant concentrations, the remanence (Br) and BH(max) increases, meanwhile, the H_CB value decreases for both 1100 and 1150^oC. The frequency dependence of reflection loss (RL) measurement given anoptimum value of-26.15 dB at frequency of 9.18 GHz which obtained by x = 0.1% mol Mn-Ti (1100^oC). The maximum absorption peak was achieved for 0.5 % mol Mn-Ti sample with ~98.3 % at 9.18 GHz. By controlling the sintering temperature and Mn-Ti dopant concentration, the RL and absorption behavior can be modified to desirable values and also indicates that higher Mn-Ti dopant concentration (0.5% mol) possess better absorbing characteristics. Furthermore, it was found that complex permitivitty and permeability values of BaFe₁₂O₁₉ can be modified by controlling the Mn-Ti dopant concentration.