Advanced Materials Research Vols. 816-817

Abstract: In drilling deep holes with small-diameter tools in particular, chip shape is a major problem along with tool rigidity. In this study, we developed a spindle machine that has regularly repeating acceleration and deceleration regions in each drill rotation (called modulated rotation) as a new drilling spidle machine that can improve chip discharge ability. For an analysis of the cutting mechanism based on the basic principles of this device and its drilling characteristics, holes were drilled in CFRP, and Ti alloy (Ti-6A1-4V) materials using a straight shank drill. The relationship between the torque and thrust of cutting resistance force was obtained to show the relationship between cutting chips shape and cutting force. The characteristics of drilling with the developed spindle device were evaluated in comparison with regular drilling methods. It was found that the torque with this device was reduced by about 10% compared with general drilling. Outstanding chip breakup was seen with Titanium alloys in particular, as a result of which chip discharge could be improved.

Abstract: In machining to CFRP material has many important problems, about necessary of high-precision machining, improvement of tool life and dispose of cutting chips etc. Especially in case of twist drill almost cant collect under 0.5 μm cutting chip, the fine-cutting chips diffuse into the sliding table and spindle head with the machine. Moreover, the fine-cutting chip is mixed and diffuse into the atmosphere. The possibility to remarkable decline of working efficiency so the dust-collection provision technology is wished. It is important also from the viewpoint of keep safety of a worker and work environment preservation because the CFRP utilizes in market for industrial structure materials, is increasing. As one method of solving this problem which aspirates and ejects cutting chip from a penetration hole through outside in the central part of the drill shank the new tool and cyclone type dust-collection system were developed. These technologies were used for perforate of CFRP material, and investigated about the cutting characteristic of the hollow type drill, and the effect of work environment improvement to dust-collection performance of cutting chips. As the result, our development machine tool and cutting tool can collect approximate 99.5% cutting chip.

Abstract: By means of thermal analysis, specific heat values of sinter with different temperatures are measured and the linear function which along with the change of temperature is got. According to the actual condition, the porous medium model which describes the cooling process is established. The influences on cooling process of specific heat with fixed and variational values are compared. With the variational specific heat, the effects on cooling process of sinter initial temperature and air temperature are discussed. The result shows that both increasing sinter initial temperature and cold air temperature can improve the exhaust heat utilization, but the later delay the cooling time.

Abstract: This paper introduces the ELID grinding parameters expert system. When we use this system, input machining parameters of the machined material and the requirement of processing precision, then it can speculate ELID grinding process parameters and electrolytic parameters for material. This system has a great practical value for the optimization of ELID grinding process, reducing processing cost and improving efficiency.

Abstract: The purpose of the present study was to evaluate the effect of filler loading on the fracture toughness of light-cured dental resin composites (DRCs). The monomer Bis-GMA and TEGDMA (75/25 wt/wt) were mixed with treated micro-sized aluminum oxide (Al₂O₃) particles ranging from 40-60 wt% as filler. The composite samples were cured with LED for 80s. The bulk density (g/cm³) and apparent porosity (%) of the samples were determined according to the ASTM standard. The fracture toughness (K_IC) values of the composites were determined using a single edge notched specimen in the three-point bending test. There was a significant difference in K_IC of the composites with different loading of Al₂O₃ particles (p < 0.05). The highest amount of filler (60 wt%) reduced the K_IC value to 1.5 MPa.m^1/2. As a conclusion, the Al₂O₃ particles used as filler loading does have an effect on the mechanical properties of DRCs.

Abstract: Multicomponent thin films (binary-SiC and ternary-SiCAl) as well as single thin films (silicon Si) were deposited using Thermionic Vacuum Arc (TVA) technology. The thin films were characterized using X-ray diffractometer (XRD, Philips PW1050, Cu K), scanning electron microscope (SEM, Zeiss EVO 50 SEM) accompanied with energy dispersive spectrometer and transmission electron microscope (TEM, Phillips CM 120 ST, 100 kV). The film is composed of nanoparticles very smoothly distributed of 15-30 nanometer size embedded in amorphous matrix film. The results reveal high hardness for SiC (10-40 GPa) and for SiCAl: low wear rate (6.16E-05 mm³/Nm).

Abstract: To remove the shortcomings from the manufacturing process it is necessary to optimize all process parameters, for all stages of technological process: the exposure, the development, the electroforming and removal of the exposed SU8. This research implies that various types of MEMS devices can be developed at a high accuracy with design flexibility, only if all process parameters are optimized. This article is presenting a study regarding typical errors arisen during manufacturing of micro-parts using UV-LIGA technology.

Abstract: We propose a scheme for realizing negative refractive index in a multilevel atomic system. The theoretical modeling has been done using density matrix approach in which the spontaneously generated coherence (SGC) is also induced. It is shown that the negative refractive index can be obtained on the effect of quantum coherence. The parameters () quantifying left-handedness in the system become more negative if the SGC is defined in the appropriate value. Furthermore, left-handed material with reduced absorption is possible by choosing appropriate parameters.

Abstract: Titania (or titanium dioxide) nanotubes are advanced materials with diverse functionalities. They have a variety of applications ranging from biology, food, cosmetics, energy and related areas. In this paper, we provide a brief description of electrochemical routes that may be used to synthesize such nanotubes rapidly over large areas. We also provide a brief overview of their energy-related.

Abstract: Local surface alloying of metallic materials by laser is an issue of interest in the scientific world and materials engineering. Laser surface alloying technology allows diffusion of alloying elements which add special features into the surface of a base material with modest properties but a low price. This paper presents the results of experimental research regarding the process of alloying on steel ST37-2 and the effects obtained after laser surface alloying.