Chih-Yu Liao

Rapid and efficient synthesis of silver nanofluid using electrical discharge machining

The electrical discharge machining (EDM) system has been proven feasible as a rapid and efficient method for silver nanofluid preparation. This study prepared the silver nano-fluid via EDMand investigated the relationship between its process parameters and product characteristics. The prior study had found that the silver nano-fluid prepared by EDMcontained both silver nanoparticles and silver ions. Silver ions had revealed the cause of the high suspension of the silver nanoparticles. To examine the relationship between the stability of silver nanofluid and the process parameters, this study quantified the relationship of process parameters to the material removal rate (MRR) of silver electrode and silver ion output rate (IOR) in the fluid, in order to achieve the most effective process parameter condition. Furthermore, the stability of silver nano-fluid was analyzed by various devices, including UV-Vis spectroscopy, size-distribution, and Zeta-potential analyzer. The effects of MRR, IOR, particle size, Zeta-potential, and optical properties of silver nanofluid under different process parameters are also discussed.

Preparation of Metallic Aluminum Compound Particles by Submerged Arc Discharge Method in Aqueous Media

Fine metal particles are produced by chemical methods, which add surfactants to control particle size and concentration. This study used the submerged arc discharge method (SADM) to prepare metal fluid containing nanoparticles and submicron particles in pure dielectric fluid (deionized water or alcohol). The process is fast and simple, and it does not require the addition of chemical agents. The SADM uses electrical discharge machining (EDM) equipment, and the key parameters of the production process include discharge voltage, current, and pulse discharge on-off duration. This study added a capacitive component between the electrodes and the electrode Z-axis regulation in the control parameters to render the aluminum fluid process smooth, which is the main difference of this article from the literature. The experimental results showed that SADM can produce aluminum particles from nanometer to submicron grade, and it can obtain different compounds from different dielectric fluids. The dielectric fluids used in this study were deionized water and ethanol, and aluminum hydroxide Al(OH)3 particles with suspending power and precipitated aluminum particles were obtained, respectively. The preparations of metal colloid and particles by the SADM process have the characteristics of low cost, high efficiency, high speed, and mass production. Thus, the process has high research value and developmental opportunities.

Motion artifacts in CT scans: a study by computer simulation and mechanical phantom

Computed tomography (CT) is one of the most important tools in the diagnosis of thoracic tumors. However, during the scanning process, respiratory motion causes changes in the position and shape of the tumor, creating motion artifacts in the CT scan. This can lead to misdiagnosis of the size and position of the tumor, and can affect the effectiveness of treatment. This study develops a computer model of the movement of the thorax, and simulates the movement of a lung tumor caused by breathing during a CT scan. We show that adjusting the CT slice thickness is sufficient to determine the center of displacement and maximum displacement of a tumor during normal breathing. This model can be applied in the clinical diagnostic use of CT equipment. It will assist in finding the position of lung tumors from motion artifacts in CT scans. The target margin for treatment can thus be defined more accurately, so that appropriate doses of radiation can be applied to the target area, and irradiation of healthy tissue avoided.

Preparation of Ag/Cu/Ti Nanofluids by Spark Discharge System and Its Control Parameters Study

This study selected silver, copper, and titanium as the research objects to explore the relationship between nanofluids properties and electrical discharge machining (EDM) processes. Regarding the products, UV-visible spectroscopy (UV-Vis) was applied to measure the concentration distribution of nanofluids; zeta-size analysis is applied for measuring nanometal particles’ Zeta-Potential and the size distribution of metallic particles in the fluid. Finally, various instruments, including scanning electron microscope (SEM), were applied to observe the shape, size, and composition ratio of metal particles after processing. According to the experimental results, the control of the discharge pulse time, in addition to affecting the concentration of metallic liquid and temperature in the process, affects the size of the metal particles after the process. As the resistivity of silver and copper is very low, at about  Ω·m, if is set to between 10~50 μs, good preparation efficiency can be obtained. The resistivity of titanium is  Ω·m, which is much larger than that of silver or copper. Hence, should be set to approximately 100 μs to achieve a good discharge success rate.

Preparation of metal nano-fluid via electrical discharge machining

In recent years, extensive researches have been studied on metal nano-fluid, especially the silver nano-fluid which can be applied in diversified fields, including mechanics, electrical, bio-medical, etc. Currently, there are many methods to prepare the silver nano-fluid. Apart from the traditional chemical method, the electrical discharge machining (EDM) system preparation method has been proven feasible. This study prepared the silver nano-fluid and investigated the relationship between its process parameters and product characteristics. Previous research has found that the silver nano-fluid prepared by EDM contained both silver nanoparticles and silver ions. To examine the relationship between the stability of silver nano-fluid and the process parameters, this study quantified the relationship of process parameters to the material removal rate (MRR) of silver electrode and silver ion output rate (IOR) in the fluid, with the attempt to achieve the most effective process parameter condition. In addition, the stability of silver nano-fluid was analyzed by various devices, including UV-Vis spectroscopy, size-distribution and zeta potential analyzer. This study successfully quantified MRR and IOR under different process parameters, and drawn important conclusions on the suspensibility of silver nano-fluid prepared by EDM. The relationship between process parameters and suspensibility of silver nano-fluid obtained in this study can serve as references for future studies on the preparation of other metal nano-fluid by EDM process.

Preparation of alumina nanoparticles by electrical discharge machining

Alumina nanoparticles have been increasingly used in the areas of medicine, biochemistry and industry. A number of chemical methods have been used for the preparation of alumina nanoparticles, including the introduction of surfactants to improve the suspensivity of the nano-sized particles. In this study, alumina (Al2O3) nanoparticles have been fabricated by using Electrical Discharge Machining (EDM) in pure water, without any chemical additives. The size distribution and chemical composition of Al2O3 nanoparticles were examined by dynamic light scattering (DLS) and energy dispersive X-ray spectroscopy (EDS), respectively. The zeta potential and surface plasmon resonance of Al2O3 nanoparticles were studied using zetasizer and ultraviolet-visible (UV-Vis) spectroscopy. The experimental results show that Al2O3 nanoparticles, with particle sizes ranging from 12 nm to 32 nm (mean 22 nm), can maintain a stable suspension in water at room temperature. Zeta potential analysis showed that a positive charge (around 50 mV) on the particle surface may contribute to the stability of the suspension. The EDM, which is an alternative method for nano-sized Al2O3 component fabrication, provides several potentially distinct advantages, including: low cost, high speed, ease of use, and ability for mass production.