Materials Science Forum Vol. 1033

Abstract: Earphones are often exported to foreign countries by sea as consumer goods. In view of the humid marine environment, the earphone packaging box is often placed with anti-mold chips to prevent mold, while the volatilization of the anti-mold chips will also cause corrosion problems. In this study, a large number of aluminum earphone connectors were corroded in the process of ocean transportation, and the corrosion products were located in the left earphone connector close to the anti-mold chips. It’s determined that sulfate and nitrate ions lead to the corrosion of the aluminum connectors, and these are the volatilization products of the anti-mold chips. This conclusion was further confirmed by the simulation test, which was carried out on the anti-mold chips and aluminum connectors at 85 °C, 85% RH humidity for 72 h. The aluminum connectors were obviously corroded, and the morphology and composition of the corrosion products were the same as those on the actual earphones. The corrosion was successfully prevented by a PTFE coating on the surface of aluminum connectors. Keywords: Earphones; Anti-mold chip; Aluminum; Corrosion; PTFE coating

Abstract: The application of ultrasonic field in the preparation of Al-Ti-C refiners can lead to the the homogenous distribution of the second phase TiAl₃ and the particle phase TiC in the matrix, thus enhancing the refinement effect. In this paper, the Al-Ti-C grain refiner was successfully prepared by the ultrasonic coupling method, and its microstructure was observed. The prepared refiner was added to pure Al to verify the refining performance, and the refining mechanism was analyzed. The results indicate that the Al-Ti-C grain refiner prepared by ultrasonic field has excellent refining performance, which reduces the grain size of Al to 100 μm, and the optimum activation refining time is 3 min. The reason is that the morphology and size of the second phase TiAl₃ and TiC in Al-Ti-C are changed by cavitation effect, acoustic streaming effect and thermal effect caused by high intensity ultrasonic, and the α-Al nucleates effectively under the synergistic of TiC and TiAl₃ particles.

Abstract: By fixing Quantum Dots (QDs) on gold electrodes with dithiol compounds, a novel Ascorbic Acid sensor without any redox mediator was desighed. First, the fabrication process of sensor was described.Sencond, the characteristics of the sensor were investigated. Third,the sensor was tested in Ascorbic Acid solutions of different concentrations.From the results,it shows that the performance of photoelectrochemical sensor were influenced by the bias voltage and the amplitude of photocurrent changed with the Ascorbic Acid concentration linearly in detection range.

Abstract: Industrial waste containing heavy metals can pollute the aquatic environment. One method that can be done to manage heavy waste is the adsorption method that uses adsorbent from cassava stem powder. This research was conducted to utilize cassava stem powder waste for the adsorption of Pb2 + metal ions. Cassava stem powder was mashed until it passed 100 mesh sieve. Cassava stems have a cellulose content of 70-80%, lignin 15-20%, ADF 15-20% and cellulose can be used as an absorber of heavy metals. The adsorption process is carried out with variations in pH, time and concentration under optimum conditions. In this adsorption involves the functional groups contained therein so that the interaction between the adsorbent with the metal ion Pb2 +. Based on the research, the optimum conditions were obtained at pH 6, 180 minutes contact time and 50 ppm concentration. This test is carried out using Atomic Absorption Spectroscopy (AAS).

Abstract: The purpose of this study was to determine and compare the effect of oven drying and spray drying treatments on the encapsulation of anthocyanin, flavonoid and phenolic extracted from watermelon rind. The analysis done in this work were as follow: total anthocyanin (TA), total flavonoid (TF) and total phenolic (TPC) content in the supernatant, yield of nanocapsule, Particle Size Analysis, and In Vitro test (test for flavonoid and phenolic release) in the supernatant food. The analysis results showed that the total anthocyanin content in watermelon rind with a spray drying treatment was 0.1113 mg/L, total flavonoid was 0.6159 g/mL, and total phenolic was 0.3410 g/mL. While using the oven, the anthocyanin content was 0.0891 mg/L, total flavonoid was 1.4590 g/mL, and total phenolic was 1.1349 g/mL. As noticed, the total content of anthocyanin resulted by using a spray dryer was greater than by using an oven. However, the total flavonoid and total phenolic resulted by using a spray dryer was smaller than by using an oven. During In Vitro analysis, the results of the release of flavonoid and phenolic resulted by using an oven into the distilled water were much larger and unstable than by using a spray dryer. This is likely because chitosan-Na (TPP) bonds are weak. Additionally, the yield of capsule on the use of spray dryer was 0.6, higher than the use of an oven, which was 0.48. While, the average particle size in the use of a spray dryer was 2.296 μm, smaller than the use of an oven, which was 61.998 μm.

Abstract: This paper aims to investigate effect of spark plasma sintering temperature on mechanical property of Ti + ZrO₂. The samples were prepared by SPS system with the different sintering temperature containing 900, 1,000, and 1,100 oC under the pressing pressure of 30 MPa in vacuum. The results show that hardness of Ti + 2 wt.% ZrO₂ alloy increases with increasing sintering temperature. The highest hardness was 363 HV while suitable temperature for sintering Ti + 2 wt.% ZrO₂ alloy was 1,100 oC. Further, the microstructure and crystal structure of all samples were single-α-phase structure with different in elements dispersion, which was related to amount of lattice expansion in the HCP structure.

Abstract: Additive manufacturing is a technology that is influencing every facet of manufacturing such as casting. 3D printing in particular has the potential to revolutionize castings in terms of precision and time taken in production. Patternless molds increase the efficiency of the casting process for large scale manufactured components. Therefore, ceramic based molds can be utilized for low temperature alloy parts such as mounting brackets. Nowadays, 3D printing technologies allow the direct printing of these molds. This is possible with the aid of CAD modelling of the casting mold which allows instant printing of patternless molds. The aim of this work is to introduce an approach to prepare a 3D design for a casting mold that can be manufactured using 3D printing technology. Mold design was made using Solidworks software according to standardized calculations from which cope and drag components were extracted. Candidates for potential mold material are highlighted along with advantages & limitations of utilizing 3D printing methodology.

Abstract: To meet the requirement for high transparency of agar gel used in tissue culture, bacteriological applications, and high-quality cosmetics and food, this study on improving the transparency of agar products was carried out by using activated carbon for decolorization and perlite for aiding filtration. The results showed that the pre-coating filtration method was better than that of the mixed slurry filtration, so an orthogonal experiment optimization was conducted using the pre-coating filtration method based on the single factor experimental results. The experimental results showed that the optimal process conditions based on the transparency index were: concentration of agar of 1.30%, activated carbon dosage of 0.80%, processing temperature of 95 °C, and treatment time of 20 min. Agar products with gel transparency of 58.93% and blue-ray whiteness value of 93.82 could be obtained under these experimental conditions. The order of the factors influencing the decolorization ratio of agar was as follows: activated carbon dosage > concentration of agar > processing temperature > treatment time. The experimental results provided effective procession methods for the production enterprises based on transparency and increased economic benefits, and it was of practical significance.

Abstract: Solder paste is mainly used for welding of resistance, capacitance, integrated circuit (IC) and other electronic components in surface mounted technology (SMT) industry, and the performance of solder paste has a significant impact on the reliability of electronic components. In this paper, processing defects, failure cases and mechanism of electronic components caused by solder paste are analyzed systematically. Improper application of solder paste during welding can lead to numerous processing defects including poor wetting, tombstoning, bridging, solder joint crack, solder ball spattering, corrosion and so on. Finally, an evaluation method of material compatibility is described in this paper, which provides a reference for ensuring the quality of electronic process material and improving the reliability of SMT products.

Abstract: The TiO₂ nanotube arrays were prepared on Ti plate by anodizing technology, and then Co (OH)₂ nanoparticles in-situ grew into TiO₂ nanotubes with "Tube-particle bonding" nanocomposited structure. Co (OH)₂ nanoparticles with a particle size of 40.5±8 nm were infiltrated in the TiO₂ nanotube arrays, and the Co (OH)₂ outside the tube presented a nanosheet structure. The specific capacitance of the Co (OH)₂/TiO₂ nanotube array composite reached 260 F/g at the current density~1 A/g. The capacity retention rate was 82.5 % after 2,000 cycles at the current density~5 A/g. The high-rate performance of the Co (OH)₂/TiO₂ nanotube array composite reached 210 F/g at the current density~10 A/g.