Advanced Materials Research Vols. 211-212

Abstract: The transverse vibration equation of an axially moving cantilever beam with tip mass is given. The instant linearized equations are set up based on Galerkin’s method. The tip mass influences to the first three order modes of the beam are computed. The calculated responses using the modes with tip mass are compared with the results using the modes without tip mass. Modes without tip mass can replace the modes with tip mass while the tip mass is small. The heavier the tip mass is, the bigger the difference of using the replacement is. It is found that the experimental result is fit well with the theoretical result using the modes with tip mass.

Abstract: Al₂O₃ Particulate reinforced TiAl based composites have been fabricated by hot press-assisted reaction synthesis (HPRS) method using Ti, Al and TiO₂ as starting materials. Effect of the TiO₂ addition on the microstructures and mechanical properties of the TiAl/Al₂O₃ composites were detailedly investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and universal properties tests. The results show that the TiO₂ addition has evident effect on phase composition and microstructure of the TiAl intermetallics, as a result, the mechanical properties of TiAl composites are improved. When the TiO₂ content is 10.58 wt %, the flexural strength and fracture toughness reach the maximum values of 537.34 MPa and 9.38 MPa·m^1/2, which are increased by 70% and 23%, respectively. The strengthening mechanism is also discussed.

Abstract: Titanium aluminide composite reinforced with in situ formed submicron Al₂O₃ has been prepared by a reactive hot press method using Cr₂O₃, Al and Ti powder as starting materials. The reaction synthesis processing is particularly investigated. Results show that the matrix of the as-prepared material is a mixture of TiAl and a small amount of Ti₃Al and Cr containing phase. Fine Al₂O₃ particles that act as reinforcing phase are dispersed along the interface of the matrix. The formation of TiAl/Al₂O₃ composite involves many transitional stages. Firstly, TiAl₃ and Ti₃Al intermediates were produced, then reducing reaction of Cr₂O₃ by Al formed Al₂O₃, and finally, the competitive solid-state diffusing reactions among Ti₃Al, TiAl and TiAl₃ produced the matrix phases of the TiAl/Al₂O₃ composite.

Abstract: A series of trivalent europium (Eu³⁺) doped double molybdate phosphors (MLa(MoO₄)₂, M = Li, Na, K) have been prepared via traditional solid state reaction method at 500-800 °C. Their crystal structures and luminescent properties have been investigated, finding that the phosphors take on single phase through X-ray diffraction patterns (XRD) sintered at 600, 700 and 800 °C for lithium, soldium and potassium salt, respectively.Their excited spectra consist of a broad band and three absorptions, in which the higher peaks locate at 400 nm and 470 nm in the region of 350-500 nm. Excited with 470 nm, the emission spectra are composed of four narrow bands and the strongest emission peak is located at 615 nm. The appropriate doping concentration of Eu³⁺ was 10 mol% for the 615 nm emission. The results indicate that this Eu³⁺ activated NaLa(MoO₄)₂ phosphors are promising yellowish red phosphor for ultraviolet (UV) and blue InGaN-based white LED.

Abstract: Quasi-static indentation (QSI) tests on plain weave carbon fiber reinforced silicon carbide (C/SiC) ceramic matrix composites (CMC) have been performed to study the damage evolution law and damage modes. Acoustic emission (AE) and Ultrasonic C-scan techniques are creatively used to monitor the damage process and detect the indented damage, respectively. The damage development process could be described by three evidently different stages: initial crack tips spreading along within the matrix, matrix cracking and delamination as well as fiber bundles breakage of different layers. The AE activity indicated that the main damage modes are matrix cracking and delamination in the first two stages, once the pressing force exceeds the peak load the damage mode will change into fiber bundles breakage. Moreover, the damage procured in the QSI test is slightly lower than that produced in the low velocity impact (LVI) test under the equivalent energy, the correspondence between the two test methods is reasonably good.

Abstract: In order to know thoroughly the thermal deformation characteristics of the dry gas seal in the synthesis gas compressor, the physical model and the thermal equilibrium model of the seal pair are established on its structural and thermal analysis. Based on finite element analysis software ANSYS, separation method are applied to resolve and analyze the temperature field and thermal-structural coupling deformation of the seal pair. The analyzed results show that the temperature of the rotating ring decreases gradually from the end face to the back face, and decreases gradually from the inner radius to the outer radius. The maximum of the temperature gradient of the rotating ring locates at the outer radius of the end face.The deformation of the stationary ring is negative conicity, the deformation of the rotating ring is positive conicity, and the later is the major reason of seal failure. Because of the thermal deformation, the end faces will form a convergent wedge. The convergent wedge favors the formation of a gaseous film, but it will lead to a increase in leakage quantity.

Abstract: Hunan with rich bamboo resources, bamboo products closely relate with the people's daily lives. According to field surveys and investigations relevant information, this paper introduce the interception process, de-oiling process, correction process, polishing process, bleaching and dyeing of the bamboo section and the "decomposition process" and "integration" process of bamboo strips, and also introduce the craft and decoration process of bamboo products in Hunan.

Abstract: The particular geological conditions of Taiwan and the onset of global climate change, have increased the intensity of precipitation, leading to greater turbulence within river channels. The erosion of riverbeds is an on-going concern, as the movement of sediment is at an all-time high. This study employs adaptive-network-based fuzzy inference to analyze and predict the erosion of river channels, and compares the results with those obtained through traditional linear regression. The Houfeng Bridge section of the Ta-Chia River in Taiwan was adopted as a case study. We investigated flow rate, gradient change, the quantity of sediment, the number of typhoons and floods, and geological conditions, as major causal factors of erosion. Results indicate that under heavy turbulence, the potential for erosion is very high in the flow areas of both Houfeung Bridge and the Chenglung Revetment. Our results are consistent with the actual conditions at the site.

Abstract: Analysis the action and function of phase change material (PCM) in building energy storage, and numerical simulation the heat storage and heat release process of heating floor filled PCM packed module by using the FLUENT software, discussion and analysis the relation of temperature distribution with energy storage and discharge time, the effects of PCM in transfer heat, stabilizing temperature changes rate and adjust floor surface temperature in energy storage floor heating are provided.

Abstract: Mill is always weighed by its longitudinal stiffness. The prediction precision of longitudinal stiffness related strip geometric accuracy. Taking 1700mm hot strip line as research object, stiffness of housing, bearing wall and roll was calculated by finite elements method(FEM), hydraulic system stiffness was obtained by theoretical formula. Analyzing vertical system and structural symmetry of mill, functional relationship between longitudinal stiffness and its components stiffness was derived according to series or parallel connection with various components. Longitudinal stiffness was the basis on thickness set-up model. Calculation result was verified by practical test.