Materials Science Forum Vols. 544-545

Abstract: The influence of angles of inclined cooling plate on cast structure and mechanical properties of cast iron was investigated experimentally in 3.1 wt.% C containing hypoeutectic semisolid cast irons fabricated by flowing the molten melt over the inclined cooling plate and pouring into a preheated permanent mold. The variables used in this study were angles of the cooling plate (5 ~ 15 deg) and the mold temperatures (500~700 deg). The microstructure of resultant specimens were characterized by measuring grain sizes of primary austenite and its solid fraction, using an optical microscope equipped with a digital image analyzer. It was shown that the spherical-like austenite (1.4 aspect ratio) was formed at the cast iron specimens prepared in employing a 10 deg angle of the inclined cooling plate. This was ascribed to the relative extent of duration time of the flowing melt which determine the solidification rate of the melt. The peak hardness and impact values were achieved in the semi-solid cast iron specimen with relatively more spherical austenite. The measured values were approximately 44HRC and 1.71 J/cm2.

Abstract: The aim of this study was to investigate the application of electrochemical technology in relation to the electrolysis of water in specific fields, including mouthrinses for the control of periodontal disease and the cleaning of contact lenses. A platinum (Pt) coated titanium (Ti) electrode cell (Pt/Ti cell, Dolki Korea Ltd.) was used for electrochemical experiments. Using the disinfection or oxidation potential of the Pt/Ti cell, sterilized water was prepared for clinical testing. An experimental group used mouthrinses with the sterilized water, where as the control group did not. In the experimental group, the gingival and plaque indices, the probing pocket depth and clinical attachment level all showed statistically significant decreases, but in the control group showed significant increases (P<0.05). The electrochemical sterilization of water using the Pt/Ti cell was also applied for the cleaning of contaminated contact lenses. SEM (Scanning Electron Microscope) data demonstrated that a foreign body adhered to the contract lens could be removed during the electrolysis of water containing the contaminated contact lens.

Abstract: The strength members, such as front-end side members, are subjected to axial compressive and bending load during collision. Therefore, it is important to consider energy absorption by the axial compression and the bending for design of effective strength members. And at the same time, it also should consider reducing weight of the members. In this study, CFRP (Carbon Fiber Reinforced Plastics) side members with single-hat-section shape were manufactured. The axial compression and the bending tests were performed for the members using universal testing machine, and the axial compression and the bending characteristics were analyzed. Stacking condition related to the energy absorption of composite materials is being considered as an issue for the structural efficiency. So the energy absorption of the member under the axial compressive load and the bending load were experimentally investigated.

Abstract: The fiber reinforced composites has high specific strength and stiffness than metallic material and are an anisotropic material whose mechanical properties, such as strength and elasticity, change with their fiber orientation state, the fiber length, the fiber aspect ratio, fiber mat structure, etc. Above all, the fiber orientation angle distribution state of fiber reinforced composite is fundamental element of mechanical properties. So, many researches on this element have been conducted by means of nondestructive method currently. The fiber distribution state is measured by intensity difference of pixel using image processing and these methods are intensity method by calculating of intensity value of pixel and counting method by calculating of fiber quantity. In this research, the fiber orientation simulation picture was constructed by plotter according to change of fiber’s diameter, length and orientation. The fiber orientation distribution state was measured by this intensity information. The fiber orientation angle distribution state measured by intensity method and counting method was compared with fiber orientation function calculation value.

Abstract: Deformation behavior of temperature gradient anneal(TGA) treated Ti-50.0Ni(at%) alloys were investigated by means of thermal cycling tests under constant load and tensile tests. TGA treated Ti-Ni alloy wires showed a sequential deformation behavior along the length of the specimen since the stress required for the B2-B19’ transformation increased with decreasing annealing temperature. Considerably large residual elongation(about 0.4 %) occurred in the TGA treated Ti-Ni alloy under the applied stress of 80 MPa, which is ascribed to the fact that yield stress of the sample annealed at 823 K is lower than the stress required for the B2-B19’ transformation of the sample annealed at 658 K.

Abstract: A WC-Co coating with self-lubricating property was deposited by detonation gun (D-gun) process, using a WC-Co powder doped with a MoS2-Ni powder, under a proper spray condition. It is proved that the MoS2 composition was kept in the resulting coating by SEM, XRD and EPMA. Evaluation on sliding wear property indicates that the MoS2 composition plays an important role in lowering both coefficient of friction and wear rate for the resulting coating, which is confirmed by observations on wear track. It suggests that the deposition of WC-Co coating with self-lubricating property by D-gun spray is feasible by controlling lubricant powder and spray conditions, which can exhibit higher sliding wear resistance.

Abstract: The purpose of this study is to introduce and discuss flux laminated strip. Flux laminated strip can be used for air atmosphere brazing. The new product is fabricated by four processes: embossing of strip; multi bending of embossed strip; flux injection; and resizing of the material. This flux laminated strip exhibits similar melting characteristics to flux cored and flux coated alloys. The flux laminated strip eliminates the need for a separate fluxing operation that is typically needed when using bulk alloy. The product ensures the correct amount of flux during the brazing process and reduces the post-braze clean time. The ability to produce a quality joint while reducing the amount of pre-braze and post-braze operations make flux laminated strip an innovative Eco-braze-materials.

Abstract: The existing forming press uses a hydraulic actuator and high powered mechanical actuator, therefore occupying a large space because of its size. This type of system is inefficient for manufacturing micro size and precision products. As forming components are small in size, forming equipment must also be small in size because the forming die and load must be small. The micro forming manufacturing system is an ultra precision forming equipment the size of several micros to millimeters and precision of sub-micro to micrometer. This micro forming manufacturing system has the advantage of minimization in manipulating distance and working space. As equipment and tools become smaller in size, minute inertia force and high natural frequency can be obtained. Therefore, high precision forming performance can be obtained. This allows the factory to quickly provide the customer with goods because the manufacturing system and process are reduced. To construct a micro manufacturing system, many technologies are necessary such as high stiffness frame, high precision actuating part, structural analysis, high precision tools and system control. In this paper Research development about a micro metal forming manufacturing system has been developed. To coincide with the purpose to be more practical, we set the development of the equipment including micro deep drawing, micro punching and micro restriking process to the goal. To achieve this goal, the miniaturized micro metal forming manufacturing system is designed and made with miniaturized size system. A micro deep drawing process and system dynamic characteristic experiments are researched using this miniaturized micro forming system. A micro deep drawing experiment is performed using micro thin foil materials (Al-1100, SUS-304). If this miniaturized micro forming technology is used, efficient material practical use in the micro forming field which uses the micro metal thin foil is possible.

Abstract: Porous concretes with continuous voids have been gaining more interest as an ecological material because of their useful functions such as water permeability and adsorption ability. So pore size distribution and the shape of especially open pores are the key point to permeability. In this study, the size and shape of pores of water permeable concrete were primary controlled by the size and shape of aggregates and secondly by the expanding agents to the cement pastes. 2 types of raw coase aggregate, type I and type C which mean fabricated by impact crusher and concrusher, were taken into uses and 3 sizes of aggregate were used, namely 3 to 5mm, 5 to 13 mm, and 13 to 20 mm. The compressive strength was found to be higher when using impact crushed aggregate. And the smaller size of aggregate was used, the higher compressive strength was achieved.

Abstract: Processing and properties of a dome-shaped piezoelectric transformer with a composition of 0.03Pb(Sb0.5Nb0.5)O3-0.03Pb(Mn1/3Nb2/3)O3-0.465PbTiO3-0.475PbZrO3 have been investigated. A dome-shaped sample was fabricated by powder injection molding. The dimension of the domeshaped sample was a 28 mm in diameter and 2.1mm in thickness with a curvature radius of 18 mm. Finite element modeling for the complicated piezoelectric transformer was applied to simulate strains and vibration mode in the sample. The high power characteristics of a dome-shaped piezoelectric transformer were examined by the lighting test for 27 and 34 watt T5 circle lamps connected in series. The series connected T5 circle lamps were successfully driven by the domeshaped piezoelectric transformer with sustaining efficiency higher than 98.5%. The transformer with ring(input)/dot(output) electrode ratio of 2.5 exhibited the maximum properties in terms of output power, efficiency and temperature stability.