Advanced Materials Research Vols. 328-330

Abstract: This study aimed to understand the effect of TiO₂ content on the thermal shock performance of Al₂O₃/TiO₂ air plasma spray coatings. Three kinds of commercial feedstock powders were used, i.e. Al₂O₃, Al₂O₃-13wt%TiO₂ and Al₂O₃-40wt%TiO₂. The resulting coatings were studied in terms of micro Vickers hardness test, XRD, SEM and thermal shock test. The last was conducted using a water quenching method. The results showed that both the coating hardness and thermal shock performance decreased with the TiO₂ content.

Abstract: A novel processing technique using a series of mixing/refluxing procedures and high-pressure crystallization (HPC) to fabricate nanodiamond/ultra high molecular weight polyethylene (ND/UHMWPE) nanocomposites for biomedical application was examined. For better mimetic lubrication, a porous structure was implemented in this study. Vitamin E as an anti-oxidation additive was also incorporated in selected porous specimens. The morphology of the specimens was investigated by transmission electron microscopy. The phase and crystal characteristics were revealed by Raman spectroscopy and X-ray diffraction. Shore D hardness was used to study the effect of the material’s porous structure and particle-induced crystallization on the bulk mechanical property. The dispersion of NDs in the UHMWPE matrix can significantly promote the crystallinity of the HPC specimens, even with a porous structure. However, the bulk hardness does not reveal this improvement in crystal microstructure.

Abstract: The a-C:H:Zr-x coatings are deposited on micro-drills using a closed field unbalanced magnetron (CFUBM) sputtering system with pulsed-DC power frequencies in the range 30 kHz to 110 kHz (the x in the term a-C:H:Zr-x is the frequency varied in the deposition process). The hardness of the various coatings is systematically explored. Additionally, the machining performance of the coated micro-drills is investigated by conducting high-speed through-hole drilling tests utilizing Printed Circuit Board (PCB) specimens. The experimental results reveal that the a-C:H:Zr-70 coating has the highest hardness (42 GPa), while the a-C:H:Zr-110 coating has the lowest hardness (26 GPa). In addition, it is shown that the a-C:H:Zr-70 coating increases the life of the micro-drill by a factor of three compared to that of an uncoated micro-drill.

Abstract: This paper integrates machine center cutting process and magnetic abrasive finishing(MAF) producing a combined process that improves the magnetic abrasive loss rate(MALR) and roughness(Ra) of aluminum alloy 6061-T6 with ladder shape of different height. The present study shows the features of the development with mathematical model based on response surface methodology (RSM) for correlating the interactive and second order influences of major machining parameters such as different size and shape abrasive of stainless, spindle speed, tool and workpiece gap, feed speed, respectively. The experiments design, regression analysis and analysis of variance are used to develop the relationships between process parameters (abrasive size, spindle speed, tool and workpiece gap, feed speed) and responses (MALR and Ra) in MAF process. Sensitivity analysis has also been carried out using developed empirical equations. The results shows that developed mathematical models can be applied to estimate the effectiveness of process parameters for MALR and Ra with a change of spindle speed affects the MALR more strongly than Ra relatively compare to other parameters.

Abstract: Rice straw is one of the main renewable energy sources in central and south Taiwan. In this study, bio-oil was produced from rice straw using a bench-scale plant that included a fluidized bed, a char removal system, and an oil collection system using an oil-recycling spray condenser. We investigated the effects of pyrolysis temperature and carrier gas flow rate on the distribution of products and on the properties of the bio-oil obtained. Experiments were conducted at reactor temperatures of 350–500 °C with carrier gas flow rates of 7.5–15 L/min and a feed rate of 1 kg/h. The results indicated that the optimum reaction temperature and carrier gas flow rate for the production of bio-oil were 450 °C and 10 L/min, respectively. The highest percentage of bio-oil in the products in these experiments was 41.3 wt%. The pH value of the bio-oil was ~4.1 and the viscosity was ~9 cSt (at 25 °C), depending on the storage time, temperature, and char content. This study establishes the operating parameters of a biomass fast pyrolysis system and provides some properties of rice straw bio-oil relevant to storage and use.

Abstract: People used the Micro Air Vehicles to patrol the military activity or explore the danger region.The important parts of Micro Air Vehicles are the flapping-wing mechanisms those can simulate the wing-motion of flying being.Hence this work is to present a systematic approach for designing new flapping-wing mechanisms with one degree of freedom that can simulate the wing-motion of long ear bats and insects.First,we analyze the topological structure and motion characteristics of existed flapping mechanisms.Then, the design criteria of the topological structure are described.Based on the design criteria of topology, the methodology of mechanism design is applied to synthesize new flapping-wing mechanisms. Finally, this research of the provide method can obtain 12 new flapping -wing mechanisms and one prototype of a flying insect mechanism.

Abstract: The rapid establishment of current technology is dependent on the effective integration of interdisciplinary science. Hence the R & D persons with multiple domain skills are strongly required for most industries. Although, the skills training for students of Vocational-Technical College and general University cannot stratify with the above need for industry. Based on the fact of drawing is the common language of industry, the designer, manufacturer, or quality control and inspection personnel use the language to communicate to each other for solving operational problems. Therefore, the purpose of this work is to train non-engineering students can learn simple mechanical drawing skills and recognize drawings. The training includes using multimedia and 3D graphic technique to write a python (open source language) program for establishing a 3D interactive graphics of a motocross suspension mechanism. As results, the students can transform visual information of the topological structure of a suspension mechanism to the dynamic digital interactive graphic. The results also show this practical technical education and training can improve the ability of non-engineering students to meet the industrial requirements.

Abstract: This study applies the finite element method (FEM) in conjunction with an abductive network to predict the workpiece surface parameters, including contact area ratio, surface roughness, skewness and kurtosis, of asperity flattening in sliding contact for metallic thin film on die material during the metal forming process. Contact area ratio, surface roughness, skewness and kurtosis are investigated for different process and material parameters, such as sliding distance, elastic modulus of film, normal pressure and bulk strain rate by finite element analysis. The abductive network is then utilized to synthesize the data sets obtained from numerical simulations, and the prediction model is established for predicting surface parameters. The predicted results of the surface parameters from the prediction model are in good agreement with the results obtained from the FEM simulation of workpiece asperity flattening in sliding contact for metallic thin film on die material.

Abstract: Mike Buzzetti proposes an optical fiber polisher which is a link-type mechanism with double flats in 1999. Buzzetti’s optical fiber polisher produce 8-shaped grinding traces to polish the end face of optical fiber connector. The purpose of this paper is to design the optimal polishing traces of single-plate optical fiber polisher to avoid the patent of Buzzetti’s mechanism. First, a link-type single-plate optical fiber polisher, which is consist 7 links and 8 joints, is proposed. Then, analyze the polishing trace, velocity, and acceleration of Buzzetti’s mechanism and new mechanism. Finally, we take the curvature scope percentage (_sp) and the velocity deviation percentage (V_dp) as the objective functions, and use global search to achieve optimized design so that the double- crank single-plate optical fiber polisher will produce the optimum polishing trace which is like the digit “8”. The results of this paper are: (1) The velocity deviation percentage of double-crank single-flat optical fiber polisher (V_dp= 61.8241%) is lower then the original mechanism (V_dp= 76.8652%). And, (2) The maximum acceleration of double-crank single-flat optical fiber polisher (a_max = 1231 cm/s²) is lower then the original mechanism (a_max= 2323.0 cm/sec²). The result indicates that the polishing effect of the double-crank single-flat optical fiber polisher is better then original mechanism.

Abstract: This research studies the effect of implanted tungsten ion on the wear mechanism after ionized tungsten was implanted into material surface as tungsten could improve surface hardening ability and increase wear-resistant property. washer-on-disk wear tests were used to study the change of average friction coefficient and total wear rate. Auger electron spectra (AES) analysis, surface profiler and Vickers hardness tester were utilized to realize the relation among hardness distribution, tungsten ion distribution, and hardened surface. From AES, it indicates that the tungsten had high density distribution when tungsten content is at the depth of 0.25 µm and 0.92 µm, among which the depth of 0.25 µm has the highest density distribution. Vickers hardness test shows that 10 gw load can obtain the highest Hv. The decrease and increase of Vickers hardness value is because tungsten is unevenly distributed. The friction coefficient decreases along with the increase of load under constant rotating speed. The friction coefficient of high rotating speed is smaller than that of low rotating speed. The total wear rate is in proportional to the load under the same turning speed.