Advanced Materials Research Vols. 146-147

Abstract: Superheated steam drying is an energy saving and effective drying technology, in which the waste heat is recycled with the loop system and the moisture removal is much faster than that of conventional low temperature drying. The computation methods for the estimation of wood mass diffusivities were evaluated and the first ten terms of the analytic solution of Fick’s Second Law was considered sufficiently accurate, but Crank’s method was rejected, due to its large errors. The experimental data show that higher temperature significantly accelerated the drying rate. In addition, no visible surface or internal checks have been found in the superheated steam dried samples (dry-bulb temperature 160, 180, 200, 220 oC). The highly effective super heated steam drying is definitely an advantage. However, samples were browned when dried above 220 oC, which may be regarded as the critical temperature for quality control.

Abstract: Detection and Recognition of the surface roughness in the images is a topic which has received a lot of attention in the field of image processing. In this paper, a new non-contact measurement method of surface roughness, by texture analysis, is developed based on Charge Coupled Device (CCD) image in planning operations. The surface image of the workpiece is first acquired using the A102f CCD digital camera. The image captured will be converted to others kinds of images (Binary, and Gray scale) to be suitable for the detection algorithms used for the different types of surface. The main Image processing approaches is used such as Smoothing process, Noise reduction, Edge detection, Region Splitting, and Hough Transform etc. The predicted surface finish values using this measurement method are found to correlate well with the conventional stylus surface finish ( Ra ) values.

Abstract: The four-phase model is used to predict the strength of particles in composite ceramic with partial debonding interphase. Firstly the external strain of three-phase cell is determined. Based on the disturbance strain tensor of three-phase cell, the micromechanical stress field of the particle is obtained. Then based on the generalized thermodynamic force of the particle in damage process, the damage equivalent stress of the particle in the three-phase cell can be calculated. As the damage equivalent stress is equal to the ultimate stress of the particle, the micromechanical strength of particles in composite ceramic with partial debonding interphase is obtained. Finally, For Al2O3-ZrO2 composite ceramic with partial debonding interphase, the variations of the micromechanical strength of particles for different orientation angle and different particle diameter are analyzed. The result shows that the micromechanical strength of particles is determined by the 50° orientation three phase cell, and has obvious size dependence. The micromechanical strength of particle will decrease when the particle diameter increase.

Abstract: In this paper, the bubble’s stability is studied in the process of preparing foam aluminum by powder metallurgy. In this work, carborundum particles, soot powder and carbon fiber are added into pure aluminum powder, respectively. The microstructure of cell wall of foam aluminum, the viscosity and surface tension of melt is investigated. It is discussed the bubble stability which is controlled through adding SiC particles, soot powder and carbon fiber, and the mechanism of bubble’s stability is analyzed. The experiment results showed that the homogeneity of bubble holes of foam aluminum is better than that which is obtained by adding SiC practical and carbon fiber into the raw materials. SEM images showed that SiC particles and carbon fiber distribute evenly on cell wall of foam aluminum. It means that during foaming a lot of SiC particles and carbon fiber distribute diffusively in liquid aluminum melted. It increases the viscosity of melt so that stability of bubble is increased.

Abstract: The mechanical properties and microstructure of SWRS82B wire rods and drawn wire were studied. Wire rods were austenitized at 850°C~900°C and held at 500°C~600°C. The results show that the finer interlamellar spacing results in the higher yield strength, tensile strength and reduction of area of the wire rod. Moreover, the finer interlamellar spacing does result in the higher yield strength of the drawn wire too.

Abstract: Polypropylene thermoplastic panel reinforced by ramie-basalt fibers was made using thermal molding method. The influences of fiber mixing mass ratio, thermal compression temperature, pressing time, pressure on the mechanical properties of thermoplastic panel were investigated. The results revealed that the optimal quality parameters were fiber mixing ratio 6:2:2 (PP: basalt: ramie), compression temperature 195 , pressing time 12min, maximum pressure 10MPa.

Abstract: 17-4PH precipitation-hardening martensite stainless steel is an important commercially available stainless steel. And the mechanical properties of this steel are very sensitive to quenching and aging process. In this paper, the effects of aging process on mechanical properties of this steel were investigated. The results show that the microstructure of this steel consists of quenched martensite, tempered martensite and precipitates. With the increase of the aging temperature, the strength decreases and the toughness increase. And the fracture mode of this steel transforms brittle fracture into toughness fracture.

Abstract: A three-component analytical model for single fibre curvature is developed in terms of the axial contractions, elastic moduli and geometrical properties of wool fibre cells. The elastic moduli of wool cells and single fibre curvature of selected Romney wools are measured. Using axial contraction data from the literature, the mean single fibre curvature is computed and compared with the measured mean value. The simulation is about the same as the measured value when the para- to orthocontraction ratio is 1.7:1.

Abstract: In the present paper, integrity assessment is made to the defects in weld metal zone of pressure piping of X52 steel using the two basic routes, FAD and CDF, which are provided in the European flaw assessment procedure SINTAP. Based on the experimental data various analysis levels of SINTAP are discussed, including the uncommonly used J-integral level in particular. Furthermore, to meet the need of the reliability assessment of pressure piping containing defects in engineering applications, probabilistic procedures are employed to obtain several probability curves with given survivability on the J-integral level with respect to the great scatter of the tested fracture toughness which is required in the J-integral level analysis.

Abstract: A method used to recognize the inner defects of 3-D braided composite materials is discussed. Firstly, the link between UT signals and the defects of 3-D braided composite material is analyzed. Then, the wavelet packet transform is used to process the ultrasonic scanning pulse signals of the defects. The characteristic quantities of signal are extracted into the BP neural network as samples. Through training the BP neural network, the recognize system of micro-cracks and pores is achieved. Finally, according to the results of experiment this classification system based on wavelet packet transform is proved to be feasible.