In order to examine how the solid-liquid interface responds to temperature variation depending on the materials characteristics, i.e. faceted phase or nonfaceted phase, the moving solid-liquid interface of transparent organic material, as a model substance for metallic materials (pivalic acid, camphene, salol, and camphor-50wt% naphthalene) was observed in-situ. Plots of the interface movement distance against time were obtained. The solid-liquid interface of the nonfaceted phase is atomically rough; it migrates in continuous mode, giving smooth curves of the distance-time plot. This is the case for pivalic acid and camphene. It was expected that the faceted phases would show different types of curves of the distance-time plot because of the atomically smooth solid-liquid interface. However, salol (faceted phase) shows a curve of the distance-time plot as smooth as that of the nonfaceted phases. This indicates that the solid-liquid interface of salol migrates as continuously as that of the nonfaceted phases. This is in contrast with the case of naphthalene, one of the faceted phases, for which the solidliquid interface migrates in “stop and go” mode, giving a stepwise curve of the distance-time plot.
PVDF Membrane has been used as material for the UF membrane through in-situ interfacial polymerization (IP) because of it’s outstanding properties such as high chemical resistance, thermal stability, and mechanical strength. In this study, surface morphology change of PVDF membrane was researched depending on evaporation time. 13% PVDF 6020 was used for casting and the evaporation time period was from 5s to 600s. The surface morphology of the membrane was investigated by scanning electron microscopy (SEM) and filtration was conducted in the cross flow method to evaluate the a performance of UF membrane. As a result, average pore size was increased with longer evaporation times which caused the decrease of rejection.
Caprylic/Capric triglyceride-in-water emulsions stabilized by Nikkol HCO-60 and HCO-10 were prepared using emulsion inversion point method at different HLB values. Emulsions with various droplet sizes were formed, and emulsion inversion point was detected by electrical conductivity. The change in emulsion droplet sizes and long term stability were monitored using laser scattering method and visual method. The droplet sizes and stability of emulsions were affected by HLB of surfactant. At emulsion inversion point, the water volume fraction increased as the HLB of surfactants decreased. According to our analysis, this resulted from a tendency of forming the W/O (water-in-oil) emulsion as the HLB of surfactants was decreased. The emulsion inversion point was clearly detected by the microscope and the electric conductivity meter. Nanometer-sized emulsion was obtained at the optimum HLB by using emulsion inversion point method. The main pattern of instability of emulsions in HLB 12 and 13 systems was Ostwald ripening. However, The patterns of instability of emulsions below 11 of HLB systems were Ostwald ripening and coalescence. All emulsions produced with surfactants in the range of HLB 8-13, creaming caused by density difference between water phase and oil phase.
Effect of phase transformation and grain-size variation of hot-pressed cobalt on its dry sliding wear was investigated. The sliding wear test was carried out against glass (83% SiO2) beads at 100N load using a pin-on-disk wear tester. Worn surfaces, cross sections, and wear debris were examined by an SEM. Phases of the specimen and wear debris were identified by an XRD. Thermal transformation of the cobalt from the hcp ε phase to the γ (fcc) phase during the wear was detected, which was deduced as the wear mechanism of the sintered cobalt.