Papers by Keyword: Erosion

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Authors: Richard Wellman, John R. Nicholls
Authors: Jun Wang, Wei Yi Li
Abstract: Abrasive waterjet machining involves the impact of micro-particles at high or ultrahigh velocities. The material removal mechanism for ductile materials has been popularly accepted for over a half century as cutting wear and deformation wear caused by the component of impact force parallel and perpendicular to the target surface respectively. However, this definition of erosion mechanisms does not give an insight into the erosion process, but describes a surface phenomenon of the event. A computational study has been undertaken to reveal the underlying mechanisms of the material removal process. Based on the findings, the impact erosion mechanisms are re-defined as material destruction through (a) failures induced by inertia, (b) failure induced by elongation, and (c) failure induced by adiabatic shear bending. This new definition appears to better represent the physical process of material deformation and removal by loose micro-particle impacts at high and ultrahigh velocities.
Authors: Thai Nguyen, King Pang, Jun Wang
Abstract: The erosion process in micro-machining of brittle glasses using a low pressure slurry jet is discussed. The process capability of the technique is assessed by examining the machined surface integrity in relation to fluid flow dynamics in micro-hole generations. The holes produced are characterised by a “W” shape in the cross section, while the surface morphology is distinguished by three zones associated with the fluid flow behaviour, i.e. a direct impact zone, a wavy zone and an accumulation zone. The surfaces appear to be smooth and without cracks, indicating a predominance of the ductile mode erosion process. With the increase of pressure, the erosion rates can be enhanced as a result of the expending of the accumulation zone while the outer diameter of the holes remains unchanged. This study shows that this technique can be used for micro-machining with high surface quality, and provides an essential understanding for further research in the avenue.
Authors: Su Wei, Wen Wu Song, Fu Jie, Cao Yong
Abstract: A 3-D model of pelton turbine bucket was built to investigate the motion characteristics of sediment particles in pelton turbines and the erosion caused by the movement. With the assistance of fluid analysis software FLUENT, A continuous phase turbulence model was estimated by the Euler equation which achieved convergence and the selected coupled calculation for solid-liquid two-phase flow with DPM model was built. It can be draw from the numerical analysis that, with the same size and sediment concentration, the inner bucket wall would suffer from the greater erosion by the relatively greater flow velocity; under the same condition of flow velocity and sediment concentration, the more serious erosion was caused by the bigger sized sediments; and the greater sediment concentration led to greater erosion, given the same flow velocity and sediment size. Based on the study, it showed that the erosion of inner wall of buckets was mainly affected by sediment size and concentration, as well as flow velocity.
Authors: Quan Lai Li, Chuan Zhen Huang, Jun Wang, Hong Tao Zhu, Cui Lian Che
Abstract: The potential of abrasive waterjet technology was investigated as a method to polish Z-blocks of synthetic quartz crystals. The polished surfaces were characterized by surface roughometer and scanning electron microscopy. The main factors affecting the surface roughness and the erosion mechanisms related to material removal were analysed. It is found that abrasive mesh, water pressure and jet incidence angle are the main factors affecting the surface roughness. By contrast, the influence of traverse speed on the surface roughness is small. Under certain controlled conditions, the erosion mechanisms of synthetic quartz crystals are plastic flow, leaving a crack-free surface by low-middle pressure micro abrasive waterjet.
Authors: Gargi Aggarwal, Vijyant Agarwal
Abstract: This paper puts across the various approaches and methods that have been proposed in the context of Fuzzy Mathematical Morphology. The underlying principles of Dilation & Erosion, the structuring elements used in various techniques, the unique variations put forth by researchers, new applications in spatial relationships, decision making, segmentation of medical images have been discussed.
Authors: Danuta Grad, Liviu Marian Ungureanu, Cristian Gabriel Alionte
Abstract: This paper presents the erosion behavior of the metallic structure of the roller coaster’s carriage using an experimental method for erosion evaluation which permits a comparison with several theoretical models. The roller coaster’s carriage body is a rigid metallic structure and most of the times, for an appealing design, the surface of the carriage is coated with a composite material which uses a non-metallic matrix. It is expected that the experimental study to be extrapolated to another mechanical system which is moving outside.
Authors: Xing Ling Tian, Nai Sheng Li, Zhi Guo Zhang, Yuan Hu, Chang Fa Zhan
Abstract: As world cultural heritage, Thousand Hand Buddhism in Dazu County of Chongqing City has been eroded Seriously after exposure to Wet atmospheric environment for about 800 years. In order to protect it, the reason of erosion should be found first. So the stones of Thousand Hand Buddhism have been analyzed using both on-site techniques(3D video microscopy, portable IR and so on) and laboratory techniques(SEM,AES and Ion chromatography etc.), and the limitations of all the above techniques are discussed. The on site results show that the stones are sandstones which contain montmorillonite, and the surface morphology of stones has changed significantly. The laboratory results show that many acidic inorganic anions can be found. and the content of SO42-is highest among all the inorganic anions, which indicates that the SO2 in the wet air should attend the reaction of the erosion. All the results show that air pollution in the Wet atmospheric environment should be the main reason of the erosion, and that on site techniques have the characteristic of nondestructive, while laboratory techniques can do more Quantitative analysis, only when they are combined can the stone relics be analyzed scientificly.This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text.
Authors: Sung Mo Hong, Min Ku Lee, G.H. Kim, Chang Kyu Rhee, K.H. Kim, Wheung Whoe Kim
Abstract: In this study the fatigue properties due to cavitation damage of flame-quenched 8.8Al-bronze (8.8Al-4.5Ni-4.5Fe-Cu) as well as current nuclear pump materials (8.8Al-bronze, SUS316 and SR50A) have been investigated by using an ultrasonic vibratory cavitation test. For this the impact loads of cavitation bubbles generated by ultrasonic vibratory device quantitatively evaluated and simultaneously the cavitation erosion experiments have been carried out. The fatigue analysis on the cavitation damage of the materials has been made from the determined impact load distribution (e.g. impact load, bubble count) and erosion parameters (e.g. incubation period, MDPR). According to Miner’s law, the exponents b of the F-N relation (Fb N = Constant) at the incubation stage (N: the number of fracture cycle) were 5.62, 4.16, 6.25 and 8.1 for the 8.8Al-bronze, flame-quenched sample, SUS316 and SR50A alloys, respectively. At steady-state, the exponents b of the F-N curve (N: the number of cycles required for a 1μm increment of MDP) were determined as 6.32, 5, 7.14 and 7.76 for the 8.8Al-bronze, flame-quenched sample, SUS316 and SR50A alloys, respectively.
Authors: Xiang Zhang, Wen Ming You, Yi Jun Zhou, Yong Sheng Li, Sheng Jie Qiu
Abstract: This paper carried out composition test, metallurgical analysis and water samples test of work environment for the centrifugal pump impeller material which experiences corrosion failure. Then combined with the scanning electron microscope and spectroscopy analysis of the fracture morphology, it conducted XRF analysis for the corrosion material to study the unsuccessful corrosion of MDS multistage centrifugal pump impeller in coal mine well water with alkalescence. The researches show that washout of solid - liquid composite phase leads to the serious erosion of pump impeller. The turbulence corrosion and cavitation are the main reasons which cause unsuccessful corrosion of this pump, while the organization defections such as dendritic graphite and binary phosphorus eutectic are important factors that lead to the severe local corrosion of impeller. Moreover, the corresponding prevention measures are proposed.
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