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Sample records for erosive wear examination

  1. Erosive tooth wear in children

    NARCIS (Netherlands)

    Carvalho, T.S.; Lussi, A.; Jaeggi, T.; Gambon, D.L.; Lussi, A.; Ganss, C.

    2014-01-01

    Erosive tooth wear in children is a common condition. Besides the anatomical differences between deciduous and permanent teeth, additional histological differences may influence their susceptibility to dissolution. Considering laboratory studies alone, it is not clear whether deciduous teeth are

  2. The interactions between attrition, abrasion and erosion in tooth wear.

    Science.gov (United States)

    Shellis, R Peter; Addy, Martin

    2014-01-01

    Tooth wear is the result of three processes: abrasion (wear produced by interaction between teeth and other materials), attrition (wear through tooth-tooth contact) and erosion (dissolution of hard tissue by acidic substances). A further process (abfraction) might potentiate wear by abrasion and/or erosion. Knowledge of these tooth wear processes and their interactions is reviewed. Both clinical and experimental observations show that individual wear mechanisms rarely act alone but interact with each other. The most important interaction is the potentiation of abrasion by erosive damage to the dental hard tissues. This interaction seems to be the major factor in occlusal and cervical wear. The available evidence is insufficient to establish whether abfraction is an important contributor to tooth wear in vivo. Saliva can modulate erosive/abrasive tooth wear, especially through formation of pellicle, but cannot prevent it. © 2014 S. Karger AG, Basel.

  3. Effect of stacking sequence on the erosive wear behavior of jute and ...

    African Journals Online (AJOL)

    Effect of stacking sequence on the erosive wear behavior of jute and juteglass fabric reinforced epoxy composite. ... morphology of the eroded surface was examined by SEM.It is conclude from the study that the erosive wear behavior of natural fiber jute can be improved significantly by hybridizing with synthetic fiber glass.

  4. Control of erosive tooth wear: possibilities and rationale

    Directory of Open Access Journals (Sweden)

    Mônica Campos Serra

    2009-06-01

    Full Text Available Dental erosion is a type of wear caused by non bacterial acids or chelation. There is evidence of a significant increase in the prevalence of dental wear in the deciduous and permanent teeth as a consequence of the frequent intake of acidic foods and drinks, or due to gastric acid which may reach the oral cavity following reflux or vomiting episodes. The presence of acids is a prerequisite for dental erosion, but the erosive wear is complex and depends on the interaction of biological, chemical and behavioral factors. Even though erosion may be defined or described as an isolated process, in clinical situations other wear phenomena are expected to occur concomitantly, such as abrasive wear (which occurs, e.g, due to tooth brushing or mastication. In order to control dental loss due to erosive wear it is crucial to take into account its multifactorial nature, which predisposes some individuals to the condition.

  5. Standard Terminology Relating to Wear and Erosion

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 The terms and their definitions given herein represent terminology relating to wear and erosion of solid bodies due to mechanical interactions such as occur with cavitation, impingement by liquid jets or drops or by solid particles, or relative motion against contacting solid surfaces or fluids. This scope interfaces with but generally excludes those processes where material loss is wholly or principally due to chemical action and other related technical fields as, for instance, lubrication. 1.2 This terminology is not exhaustive; the absence of any particular term from this collection does not necessarily imply that its use within this scope is discouraged. However, the terms given herein are the recommended terms for the concepts they represent unless otherwise noted. 1.3 Certain general terms and definitions may be restricted and interpreted, if necessary, to make them particularly applicable to the scope as defined herein. 1.4 The purpose of this terminology is to encourage uniformity and accuracy ...

  6. Elevated temperature erosive wear of metallic materials

    International Nuclear Information System (INIS)

    Roy, Manish

    2006-01-01

    Solid particle erosion of metals and alloys at elevated temperature is governed by the nature of the interaction between erosion and oxidation, which, in turn, is determined by the thickness, pliability, morphology, adhesion characteristics and toughness of the oxide scale. The main objective of this paper is to critically review the present state of understanding of the elevated temperature erosion behaviour of metals and alloys. First of all, the erosion testing at elevated temperature is reviewed. This is followed by discussion of the essential features of elevated temperature erosion with special emphasis on microscopic observation, giving details of the erosion-oxidation (E-O) interaction mechanisms. The E-O interaction has been elaborated in the subsequent section. The E-O interaction includes E-O maps, analysis of transition criteria from one erosion mechanism to another mechanism and quantification of enhanced oxidation kinetics during erosion. Finally, the relevant areas for future studies are indicated. (topical review)

  7. Dental erosive wear and salivary flow rate in physically active young adults

    Directory of Open Access Journals (Sweden)

    Mulic Aida

    2012-03-01

    Full Text Available Abstract Background Little attention has been directed towards identifying the relationship between physical exercise, dental erosive wear and salivary secretion. The study aimed i to describe the prevalence and severity of dental erosive wear among a group of physically active young adults, ii to describe the patterns of dietary consumption and lifestyle among these individuals and iii to study possible effect of exercise on salivary flow rate. Methods Young members (age range 18-32 years of a fitness-centre were invited to participate in the study. Inclusion criteria were healthy young adults training hard at least twice a week. A non-exercising comparison group was selected from an ongoing study among 18-year-olds. Two hundred and twenty participants accepted an intraoral examination and completed a questionnaire. Seventy of the exercising participants provided saliva samples. The examination was performed at the fitness-centre or at a dental clinic (comparison group, using tested erosive wear system (VEDE. Saliva sampling (unstimulated and stimulated was performed before and after exercise. Occlusal surfaces of the first molars in both jaws and the labial and palatal surfaces of the upper incisors and canines were selected as index teeth. Results Dental erosive wear was registered in 64% of the exercising participants, more often in the older age group, and in 20% of the comparison group. Enamel lesions were most observed in the upper central incisors (33%; dentine lesions in lower first molar (27%. One fourth of the participants had erosive wear into dentine, significantly more in males than in females (p = 0.047. More participants with erosive wear had decreased salivary flow during exercise compared with the non-erosion group (p Conclusion The study showed that a high proportion of physically active young adults have erosive lesions and indicate that hard exercise and decreased stimulated salivary flow rate may be associated with such

  8. Erosive wear of selected materials for fossil energy applications

    Energy Technology Data Exchange (ETDEWEB)

    Adler, Thomas A.; Rawers, James C.; Tylczak, Joseph H.; Hawk, Jeffrey A.

    2001-01-01

    A number of materials have been evaluated to determine their erosion resistance for fossil energy applications. This is part of a larger program to study wear and corrosion at Albany Research Center. This paper will present the results for some of these materials, including FeAl, FeAl cermets, WC-Co cemented carbides, Si3N4-MoSi2, Si3N4, Stellite 6B, white cast irons and 440C steel. Trends in erosion rates due to material properties and erosive conditions will be presented. FeAl cermets performed well compared to the WC-Co cemented carbides. The interparticle spacing of the WC-Co cemented carbides correlated with the erosion rate. The erosion rate of the WC-Co cemented carbides decreased as the interparticle spacing decreased. It is important to realize that erosion resistance is not an intrinsic material property, but is a system response. A change in the wear environment can significantly alter the relative rankings of materials with respect to their wear rate. For example, at relatively low velocities, the carbides in the white cast irons are more erosion resistant than the matrix, while at higher velocities the matrix is more erosion resistant.

  9. Toothbrushing after an erosive attack: will waiting avoid tooth wear?

    Science.gov (United States)

    Lussi, Adrian; Lussi, Jonas; Carvalho, Thiago S; Cvikl, Barbara

    2014-10-01

    The purpose of this study was to determine if storage for up to 4 h in human saliva results in a decrease of erosive tooth wear (ETW) and in an increase of surface microhardness (SMH) of enamel samples after an erosive attack with subsequent abrasion. Furthermore, we determined the impact of individual salivary parameters on ETW and SMH. Enamel samples were distributed into five groups: group 1 had neither erosion nor saliva treatment; groups 2-5 were treated with erosion, then group 2 was placed in a humid chamber and groups 3-5 were incubated in saliva for 30 min, 2 h, and 4 h, respectively. After erosion and saliva treatments, all groups were treated with abrasion. Surface microhardness and ETW were measured before and after erosion, incubation in saliva, and abrasion. Surface microhardness and ETW showed significant changes throughout the experiment: SMH decreased and ETW increased in groups 2-5, regardless of the length of incubation in saliva. The results of groups 3-5 (exposed to saliva) were not significantly different from those of group 2 (not exposed to saliva). Exposure of eroded enamel to saliva for up to 4 h was not able to increase SMH or reduce ETW. However, additional experiments with artificial saliva without proteins showed protection from erosive tooth wear. The recommendation to postpone toothbrushing of enamel after an erosive attack should be reconsidered. © 2014 Eur J Oral Sci.

  10. Enamel erosion and mechanical tooth wear in medieval Icelanders.

    Science.gov (United States)

    Richter, Svend; Eliasson, Sigfus Thor

    2016-01-01

    The Icelandic Sagas are an important source of information on the way of life and diet habits in Iceland and possibly other Nordic countries 1000 years ago. Archaeological human skull material worldwide has revealed extensive tooth wear, with the main cause believed to be coarse diet. From a graveyard near volcano Hekla, 66 skeletons dated from before 1104 were excavated. The purpose of this study was to determine the main causes of tooth wear in Icelanders 1000 years ago. Forty-nine skulls were available for research. Two methods were used to evaluate tooth wear and seven for age estimation. An attempt was made to determine the main causes of tooth wear in the light of likely diet and beverage consumption according to a computer search on food and drink customs described in the Icelandic Sagas. Tooth wear was extensive in all groups, increasing with age. The highest score was on first molars, with no difference between sexes. It had all the similarities seen in wear from coarse diet. In some instances it had similar characteristics to those seen in erosion in modern Icelanders consuming excessive amounts of soft drinks. According to the Sagas, acidic whey was a daily drink and used for preservation of food in Iceland until recently. Since acidic whey has considerably high dental erosive potential, it is postulated that consumption of acidic drinks and food, in addition to a coarse and rough diet, played a significant role in the dental wear of ancient Icelanders.

  11. Testing of a Fiber Optic Wear, Erosion and Regression Sensor

    Science.gov (United States)

    Korman, Valentin; Polzin, Kurt A.

    2011-01-01

    The nature of the physical processes and harsh environments associated with erosion and wear in propulsion environments makes their measurement and real-time rate quantification difficult. A fiber optic sensor capable of determining the wear (regression, erosion, ablation) associated with these environments has been developed and tested in a number of different applications to validate the technique. The sensor consists of two fiber optics that have differing attenuation coefficients and transmit light to detectors. The ratio of the two measured intensities can be correlated to the lengths of the fiber optic lines, and if the fibers and the host parent material in which they are embedded wear at the same rate the remaining length of fiber provides a real-time measure of the wear process. Testing in several disparate situations has been performed, with the data exhibiting excellent qualitative agreement with the theoretical description of the process and when a separate calibrated regression measurement is available good quantitative agreement is obtained as well. The light collected by the fibers can also be used to optically obtain the spectra and measure the internal temperature of the wear layer.

  12. Prevalence of erosive tooth wear and associated factors in a group of Mexican adolescents.

    Science.gov (United States)

    González-Aragón Pineda, Álvaro Edgar; Borges-Yáñez, Socorro Aída; Lussi, Adrian; Irigoyen-Camacho, María Esther; Angeles Medina, Fernando

    2016-02-01

    Erosive tooth wear is the irreversible loss of dental hard tissue as a result of chemical processes. When the surface of a tooth is attacked by acids, the resulting loss of structural integrity leaves a softened layer on the tooth's surface, which renders it vulnerable to abrasive forces. The authors' objective was to estimate the prevalence of erosive tooth wear and to identify associated factors in a sample of 14- to 19-year-old adolescents in Mexico. The authors performed a cross-sectional study on a convenience sample (N = 417) of adolescents in a school in Mexico City, Mexico. The authors used a questionnaire and an oral examination performed according to the Lussi index. The prevalence of erosive tooth wear was 31.7% (10.8% with exposed dentin). The final logistic regression model included age (P < .01; odds ratio [OR], 1.64; 95% confidence interval [CI], 1.26-2.13), high intake of sweet carbonated drinks (P = .03; OR, 1.81; 95% CI, 1.06-3.07), and xerostomia (P = .04; OR, 2.31; 95% CI, 1.05-5.09). Erosive tooth wear, mainly on the mandibular first molars, was associated with age, high intake of sweet carbonated drinks, and xerostomia. Knowledge regarding erosive tooth wear in adolescents with relatively few years of exposure to causal factors will increase the focus on effective preventive measures, the identification of people at high risk, and early treatment. Copyright © 2016 American Dental Association. Published by Elsevier Inc. All rights reserved.

  13. Prevalencia de erosión dental en niños de 6 a 12 años de edad utilizando el índice Basic Erosive Wear Examination (BEWE

    Directory of Open Access Journals (Sweden)

    Karla Rosella Baltuano Songhurst

    2016-01-01

    Full Text Available Objetivos: El objetivo de este estudio fue determinar la prevalencia, distribución y severidad de erosión dental en niños de 6 a 12 años de edad de la institución educativa pública Domingo Faustino Sarmiento, Lima-Perú. Material y métodos: Una muestra aleatoria de 247 niños de primaria fueron evaluados clínicamente para medir la erosión dental utilizando el índice Basic Erosive Wear Examination (BEWE, obteniendo un score acumulativo el cual posteriormente es comparado con el cuadro de niveles de riesgo/manejo clínico propio del índice. Se realizó un análisis descriptivo de las variables presencia de erosión dental, género, edad, localización de la lesión. Resultados: La prevalencia de erosión dental fue de 9.31% y la media y DS del score BEWE fue 0.25±0.90. Conclusiones: La erosión dental en niños de 6 a 12 años encontrada en esta institución educativa es menor a la de otros estudios epidemiológicos realizados en escuelas de otras partes del mundo. Este tipo de estudio epidemiológico puede ser viable en niños de este rango de edad de otras partes del Perú, en donde las costumbres, hábitos alimenticios y otros factores varían notablemente.

  14. Erosive Wear Characterization of Materials for Lunar Construction

    Science.gov (United States)

    Mpagazehe, Jeremiah N.; Street, Kenneth W., Jr.; Delgado, Irebert R.; Higgs, C. Fred, III

    2012-01-01

    NASA s Apollo missions revealed that exhaust from the retrorockets of landing spacecraft may act to significantly accelerate lunar dust on the surface of the Moon. A recent study by Immer et al. (C. Immer, P.T. Metzger, P.E. Hintze, A. Nick, and R. Horan, Apollo 12 Lunar Module exhaust plume impingement on Lunar Surveyor III, Icarus, Vol. 211, pp. 1089-1102, 2011) investigated coupons returned to Earth from the Surveyor III lunar probe which were subjected to lunar dust impingement by the Apollo 12 Lunar Module landing. Their study revealed that even with indirect impingement, the spacecraft sustained erosive damage from the fast-moving lunar dust particles. In this work, results are presented from a series of erosive wear experiments performed on 6061 Aluminum using the JSC-1AF lunar dust simulant. Optical profilometry was used to investigate the surface after the erosion process. It was found that even short durations of lunar dust simulant impacting at low velocities produced substantial changes in the surface.

  15. Erosive Wear of Inconel 625 Alloy Coatings Deposited by CMT Method

    Directory of Open Access Journals (Sweden)

    Solecka M.

    2016-06-01

    Full Text Available The article presents the investigation results concerning the determination of the characteristics of erosive wear caused by the impact of Al2O3 solid particles on the surface of Inconel 625 alloy after plastic working and the same material after weld cladding process using the CMT method. Erosion wear tests were performed at two temperatures: 20°C and 650°C. The erosion tests were conducted using the standard ASTM G76. A jet with a specified abrasive waight was directed to the surface of the tested material at an α impingement angle varied in the range of 30-90° at a velocity imparted to the abrasive by the medium, which was compressed air. The eroded surface was examined using a scanning electron microscope (SEM, while the depths of craters caused by the erosion tests were measured with an optical profilometer. The predominant mechanisms of the formation of mass losses during solid particle erosion were microcutting and microfissuring.

  16. Bedrock erosion by sliding wear in channelized granular flow

    Science.gov (United States)

    Hung, C. Y.; Stark, C. P.; Capart, H.; Smith, B.; Maia, H. T.; Li, L.; Reitz, M. D.

    2014-12-01

    Boundary forces generated by debris flows can be powerful enough to erode bedrock and cause considerable damage to infrastructure during runout. Bedrock wear can be separated into impact and sliding wear processes. Here we focus on sliding wear. We have conducted experiments with a 40-cm-diameter grainflow-generating rotating drum designed to simulate dry channelized debris flows. To generate sliding erosion, we placed a 20-cm-diameter bedrock plate axially on the back wall of the drum. The rotating drum was half filled with 2.3-mm-diameter grains, which formed a thin grain-avalanching layer with peak flow speed and depth close to the drum axis. The whole experimental apparatus was placed on a 100g-ton geotechnical centrifuge and, in order to scale up the stress level, spun to a range of effective gravity levels. Rates and patterns of erosion of the bedrock plate were mapped after each experiment using 3d micro-photogrammetry. High-speed video and particle tracking were employed to measure granular flow dynamics. The resulting data for granular velocities and flow geometry were used to estimate impulse exchanges and forces on the bedrock plate. To address some of the complexities of granular flow under variable gravity levels, we developed a continuum model framed around a GDR MiDi rheology. This model allowed us to scale up boundary forcing while maintaining the same granular flow regime, and helped us to understand important aspects of the flow dynamics including e.g. fluxes of momentum and kinetic energy. In order to understand the detailed processes of boundary forcing, we performed numerical simulations with a new contact dynamics model. This model confirmed key aspects of our continuum model and provided information on second-order behavior such as fluctuations in the forces acting on the wall. By combining these measurements and theoretical analyses, we have developed and calibrated a constitutive model for sliding wear that is a threshold function of

  17. A new in situ model to study erosive enamel wear, a clinical pilot study.

    NARCIS (Netherlands)

    Ruben, J.L.; Truin, G.J.; Bronkhorst, E.M.; Huysmans, M.C.D.N.J.M.

    2017-01-01

    OBJECTIVES: To develop an in situ model for erosive wear research which allows for more clinically relevant exposure parameters than other in situ models and to show tooth site-specific erosive wear effect of an acid challenge of orange juice on enamel. METHODS: This pilot study included 6

  18. Measurements of Erosion Wear Volume Loss on Bare and Coated Polymer Matrix Composites

    Science.gov (United States)

    Miyoshi, Kazuhisa; Sutter, James K.; Mondry, Richard J.; Bowman, Cheryl; Ma, Kong; Horan, Richard A.; Naik, Subhash K.; Cupp, Randall J.

    2003-01-01

    An investigation was conducted to examine the erosion behavior of uncoated and coated polymer matrix composite (PMC) specimens subjected to solid particle impingement using air jets. The PMCs were carbon-Kevlar (DuPont, Wilmington, DE) fiber-epoxy resin composites with a temperature capability up to 393 K (248 F). Tungsten carbide-cobalt (WC-Co) was the primary topcoat constituent. Bondcoats were applied to the PMC substrates to improve coating adhesion; then, erosion testing was performed at the University of Cincinnati. All erosion tests were conducted with Arizona road-dust (ARD), impinging at angles of 20 and 90 on both uncoated and two-layer coated PMCs at a velocity of 229 m/s and at a temperature of 366 K (200 F). ARD contains primarily 10-m aluminum oxide powders. Vertically scanning interference microscopy (noncontact, optical profilometry) was used to evaluate surface characteristics, such as erosion wear volume loss and depth, surface topography, and surface roughness. The results indicate that noncontact, optical interferometry can be used to make an accurate determination of the erosion wear volume loss of PMCs with multilayered structures while preserving the specimens. The two-layered (WC-Co topcoat and metal bondcoat) coatings on PMCs remarkably reduced the erosion volume loss by a factor of approximately 10. The tenfold increase in erosion resistance will contribute to longer PMC component lives, lower air friction, reduced related breakdowns, decreased maintenance costs, and increased PMC reliability. The decrease in the surface roughness of the coated vanes will lead to lower air friction and will subsequently reduce energy consumption. Eventually, the coatings could lead to overall economic savings.

  19. Consensus Report of the European Federation of Conservative Dentistry: Erosive tooth wear – diagnosis and management.

    Science.gov (United States)

    Carvalho, Thiago S; Colon, Pierre; Ganss, Carolina; Huysmans, Marie-Charlotte; Lussi, Adrian; Schlueter, Nadine; Schmalz, Gottfried; Shellis, Peter R; Björg Tveit, Anne; Wiegand, Annette

    2016-01-01

    Due to an increased focus on erosive tooth wear (ETW), the European Federation of Conservative Dentistry (EFCD) considered ETW as a relevant topic for generating this consensus report. This report is based on a compilation of the scientific literature, an expert conference, and the approval by the General Assembly of EFCD. ETW is a chemical-mechanical process resulting in a cumulative loss of hard dental tissue not caused by bacteria, and it is characterized by loss of the natural surface morphology and contour of the teeth. A suitable index for classification of ETW is the basic erosive wear examination (BEWE). Regarding the etiology, patient-related factors include the predisposition to erosion, reflux, vomiting, drinking and eating habits, as well as medications and dietary supplements. Nutritional factors relate to the composition of foods and beverages, e.g., with low pH and high buffer capacity (major risk factors), and calcium concentration (major protective factor). Occupational factors are exposition of workers to acidic liquids or vapors. Preventive management of ETWaims at reducing or stopping the progression of the lesions. Restorative management aims at reducing symptoms of pain and dentine hypersensitivity, or to restore esthetic and function, but it should only be used in conjunction with preventive strategies. Effective management of ETW includes screening for early signs of ETW and evaluating all etiological factors. ETW is a clinical condition, which calls for the increased attention of the dental community and is a challenge for the cooperation with other medical specialities.

  20. Does erosive tooth wear affect the oral health-related quality of life of preschool children?

    OpenAIRE

    TELLO, Gustavo; OLIVEIRA, Luciana Butini; MURAKAMI, Christiana; BONINI, Gabriela Cunha; ABANTO, Jenny; BÖNECKER, Marcelo

    2017-01-01

    ABSTRACT Objective: The aim of this study was to investigate the impact of erosive tooth wear on the Oral Health-Related Quality of life (OHRQoL) of preschool children. Methods: Dental examinations were conducted on 815 children aged 3-4 years during the Children’s Vaccination National Day when their parents were also invited to answer the Brazilian Early Childhood Oral Health Impact Scale (B-ECOHIS). ETW prevalence and severity were measured using a modified version of the O’Brien index (1...

  1. "Kicking Up Some Dust": An Experimental Investigation Relating Lunar Dust Erosive Wear to Solar Power Loss

    Science.gov (United States)

    Mpagazehe, Jeremiah N.; Street, Kenneth W., Jr.; Delgado, Irebert R.; Higgs, C. Fred, III

    2013-01-01

    The exhaust from retrograde rockets fired by spacecraft landing on the Moon can accelerate lunar dust particles to high velocities. Information obtained from NASA's Apollo 12 mission confirmed that these high-speed dust particles can erode nearby structures. This erosive wear damage can affect the performance of optical components such as solar concentrators. Solar concentrators are objects which collect sunlight over large areas and focus the light into smaller areas for purposes such as heating and energy production. In this work, laboratory-scale solar concentrators were constructed and subjected to erosive wear by the JSC-1AF lunar dust simulant. The concentrators were focused on a photovoltaic cell and the degradation in electrical power due to the erosive wear was measured. It was observed that even moderate exposure to erosive wear from lunar dust simulant resulted in a 40 percent reduction in power production from the solar concentrators.

  2. CFD Prediction of Erosion Wear in Centrifugal Slurry Pumps for Dilute Slurry Flows

    Directory of Open Access Journals (Sweden)

    K. V. Pagalthivarthi

    2011-12-01

    Full Text Available The paper discusses numerical prediction of erosion wear trends in centrifugal pump casing pumping dilute slurries. The casing geometry is considered two-dimensional. Discrete Phase Model (DPM in FLUENT 6.1® is utilized to obtain dilute slurry flow field through the pump casing employing two-way coupling. Standard k — ε model is used for turbulence. Effect of several operational parameters viz. pump flow rate, pump speed (RPM, particle diameter and various geometry conditions viz. tongue curvature, slope of the discharge pipe and casing width is studied. Qualitative trends of erosion wear is described for these operational and geometric parameters with an idea to lower the wear rates and to make the wear pattern along the casing wall as uniform as possible. For example, with increase in pump flow rate, wear rates tends to even out whereas with increased casing width, wear rates are found to decrease.

  3. Study of corrosive-erosive wear behaviour of Al6061/albite composites

    International Nuclear Information System (INIS)

    Sharma, S.C.; Krishna, M.; Murthy, H.N. Narasimha; Tarachandra, R.; Satyamoorthy, M.; Bhattacharyya, D.

    2006-01-01

    This investigation analyses the influence of dispersed alumina particles on the wear behaviour of the Al/albite composites in a corrosive environment. The composites were prepared by modified pressure die-casting technique. The corrosive-erosive wear experiments were carried out on a proprietary corrosion-erosion wear tester to study the wear characteristics of the composites. The slurry was made up of water and alumina (size: 90-150 μm, proportion: 0-30 wt.%), while H 2 SO 4 (0.01, 0.1 and 1N) was added to create the corrosive conditions. Experiments were arranged to test the relationships among the corrosive-erosive wear rate, concentrations of H 2 SO 4 and alumina in the slurry, weight percent of albite in the composite, erosion speed and distance. Wear rate varies marginally at low speeds but sharply increases at higher speeds. The corrosive wear rate logarithmically increased with the increasing concentration of the corrosive medium. The effect of abrasive particles and corrosion medium on the wear behaviour of the composite is explained experimentally, theoretically and using scanning electron microscopy

  4. Multifactorial analysis of factors associated with the incidence and progression of erosive tooth wear

    NARCIS (Netherlands)

    El Aidi, H.; Bronkhorst, E.M.; Huysmans, M.C.D.N.J.M.; Truin, G.J.

    2011-01-01

    To prevent erosive tooth wear, early diagnosis and identification of causative factors are essential. The aim of the present 3-year longitudinal study was to investigate the association between a broad collection of biological and behavioural factors and the incidence and progression of erosive

  5. Dental approach to erosive tooth wear in gastroesophageal reflux ...

    African Journals Online (AJOL)

    2014-06-02

    Jun 2, 2014 ... Abstract. Background: The duration of gastro-esophageal reflux disease (GERD), the frequency of reflux, the pH and type of acid, and the quality and quantity of saliva affect the severity of dental erosion due to GERD. Objective: To ... Some medications cause salivary hypofunction and dental erosion; drugs ...

  6. Erosive wear of a surface coated hydroturbine steel

    Indian Academy of Sciences (India)

    Administrator

    Gun on a hot rolled 21Cr–4Ni–N steel meant for fabrication of hydro turbine underwater parts. The coatings have been characterized for microstructure, porosity, microhardness and crystalline nature. The erosion experiments were carried out using an air jet erosion test rig at a velocity of 120 ms. –1 and impingement angles.

  7. Dental approach to erosive tooth wear in gastroesophageal reflux ...

    African Journals Online (AJOL)

    Background: The duration of gastro-esophageal reflux disease (GERD), the frequency of reflux, the pH and type of acid, and the quality and quantity of saliva affect the severity of dental erosion due to GERD. Objective: To summarize the diagnostic protocol and treatment of dental erosion due to GERD. Methods: A Medline ...

  8. Prevention of erosive/abrasive enamel wear due to orange juice modified with dietary supplements.

    Science.gov (United States)

    Wegehaupt, Fj; Günthart, N; Sener, B; Attin, T

    2011-07-01

    The aim of this study was to evaluate the erosive/abrasive enamel wear after contact with orange juices modified with different dietary supplements. A total of 96 bovine enamel samples were prepared and allocated to eight groups (1-8; n = 12). Samples were eroded (120 s) in 200 ml of the following eight solutions: 1: water (control), 2: orange juice, 3: water + calcium effervescent tablet, 4: orange juice + calcium effervescent tablet, 5: water + 0.75 g acid/base regulating powder (Probase), 6: water + 0.375 g Probase, 7: orange juice + 0.75 g Probase and 8: orange juice + 0.375 g Probase. After erosion, the samples were brushed with 40 brushing strokes (load 2.5 N). Enamel wear was measured using surface profilometry after 20 and 40 cycles of erosion/abrasion respectively. Highest mean enamel wear (± SD) after 20 and 40 cycles of erosion/abrasion was observed for the unmodified orange juice (group 2) (0.605 ± 0.240 μm; 1.375 ± 0.496 μm respectively). The enamel wear in all other groups (3-8) was significantly lower (P abrasive enamel wear induces by orange juice and tooth brushing could be reduced significantly by modification with free available dietary supplements. © 2011 John Wiley & Sons A/S.

  9. The Influence of Behavioural and Sociodemographic Risk Indicators on Erosive Tooth Wear in Flemish Adolescents, Belgium.

    Science.gov (United States)

    Marro, Francisca; Jacquet, Wolfgang; Bottenberg, Peter; Martens, Luc

    2018-01-01

    Although Belgium has recently been ranked as the second highest consumer of soft drinks in Europe, no data on erosive tooth wear (ETW) are currently available. Therefore, the aim of this cross-sectional study was to determine the prevalence and associated risk indicators of ETW in adolescents residing in the region of Flanders, Belgium. Convenience sampling was used to recruit participants from different types of Belgian schools: general and vocational/technical education. Three calibrated dentists performed the dental examinations and a self-reported questionnaire was applied to evaluate risk indicators related with ETW. ETW was classified using the Basic Erosive Wear Examination (BEWE) index, and the overall prevalence was calculated using BEWE sum >0. The Kruskal-Wallis test, the Mann-Whitney U test, and logistic regression analysis were performed to evaluate frequencies and risk associations. From a total of 613 recruited adolescents (mean age: 15.1 years, SD: 0.8), 48.6% presented at least one affected tooth surface by ETW (BEWE sum >0), 14.4% (n = 88) scored BEWE sum >2, and the highest score obtained was BEWE sum = 8. Two predictive variables were found to have an association with ETW: vocational/technical type of education (OR: 1.49; 95% CI: 1.03-2.13) and frequent consumption of soft drinks (OR: 2.08; 95% CI: 1.38-3.14). In conclusion, ETW is a common condition presented with low severity among Flemish adolescents. Additionally, the frequent consumption of soft drinks and being part of a vocational/technical education appear to be risk indicators for ETW in this population. The latter indicates the need for specific orientated oral health promotion programmes for the prevention of ETW in Flemish adolescents. © 2018 S. Karger AG, Basel.

  10. Use of dentifrices to prevent erosive tooth wear: harmful or helpful?

    Directory of Open Access Journals (Sweden)

    Ana Carolina Magalhães

    2014-01-01

    Full Text Available Dental erosion is the loss of dental hard tissues caused by non-bacterial acids. Due to acid contact, the tooth surface becomes softened and more prone to abrasion from toothbrushing. Dentifrices containing different active agents may be helpful in allowing rehardening or in increasing surface resistance to further acidic or mechanical impacts. However, dentifrices are applied together with brushing and, depending on how and when toothbrushing is performed, as well as the type of dentifrice and toothbrush used, may increase wear. This review focuses on the potential harmful and helpful effects associated with the use of dentifrices with regard to erosive wear. While active ingredients like fluorides or agents with special anti-erosive properties were shown to offer some degree of protection against erosion and combined erosion/abrasion, the abrasive effects of dentifrices may increase the surface loss of eroded teeth. However, most evidence to date comes from in vitro and in situ studies, so clinical trials are necessary for a better understanding of the complex interaction of active ingredients and abrasives and their effects on erosive tooth wear.

  11. EXPERIMENTAL INVESTIGATION OF EROSIVE WEAR ON THE HIGH CHROME CAST IRON IMPELLER OF SLURRY DISPOSAL PUMP USING RESPONSE SURFACE METHODOLOGY

    Directory of Open Access Journals (Sweden)

    Jasbir Singh Ratol

    2012-07-01

    Full Text Available Erosive wear occurs on the impeller and volute casing of the slurry disposal pump due to the impact of the ash particles on the impeller with a high velocity. Due to erosive wear, pump life become very short. The service life of centrifugal pump, handling slurry can be increased by reducing the erosive wear. In the present work, the experimental investigation of erosive wear has been carried out on the high speed slurry erosion tester to understand the effects of the ash concentration in slurry, rotational speed of the pump impeller and ash particle size on erosive wear. The erosive wear behaviour of high chrome cast iron was investigated by Response surface methodology (RSM. Analysis of variance (ANOVA was used for statistical analysis and the modeled values for the response were obtained with the help of modeled equation. The result shows that the ash concentration in slurry and kinetic energy of the moving particles highly contributes to erosive wear of pump impeller as compared to the ash particle size.

  12. Experimental Investigation of Erosive Wear on the High Chrome Cast Iron Impeller of Slurry Disposal Pump Using Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Sunil Kumar

    2012-05-01

    Full Text Available Erosive wear occurs on the impeller and volute casing of the slurry disposal pump due to the impact of the ash particles on the impeller with a high velocity. Due to erosive wear, pump life become very short. The service life of centrifugal pump, handling slurry can be increased by reducing the erosive wear. In the present work, the experimental investigation of erosive wear has been carried out on the high speed slurry erosion tester to understand the effects of the ash concentration in slurry, rotational speed of the pump impeller and ash particle size on erosive wear. The erosive wear behavior of high chrome cast iron was investigated by Response surface methodology (RSM. Analysis of variance (ANOVA was used for statistical analysis and the modeled values for the response were obtained with the help of modeled equation. The result shows that the ash concentration in slurry and kinetic energy of the moving particles highly contributes to erosive wear of pump impeller as compared to the ash particle size.

  13. Erosion by sliding wear in granular flows: Experiments with realistic contact forces

    Science.gov (United States)

    Stark, C. P.; Hung, C. Y.; Smith, B.; Li, L.; Grinspun, E.; Capart, H.

    2015-12-01

    Debris flow erosion is a powerful and sometimes dominant process in steep channels. Despite its importance, this phenomenon is relatively little studied in the lab. The large drum experiments of Hsu are a notable exception, in which almost-field-scale impact forces were generated at the head of a synthetic debris flow whose properties (grain size, proportion of fines, etc) were varied widely.A key challenge in these and similar experiments is to explore how erosion rate varies as a function of the scale of the flow (thereby varying inertial stresses, impact forces, etc). The geometrical limitations of most lab experiments, and their short run time, severely limit the scope of such explorations.We achieve this scale exploration in a set of drum erosion experiments by varying effective gravity across several orders of magnitude (1g, 10g, 100g) in a geotechnical centrifuge. By half-filling our 40cm-diameter drum with dry 2.3mm grains, placing a synthetic rock plate at the back and a glass plate at the front 3cm apart, and rotating the drum at 1-50rpm, we simulate wear in a channelized dry granular flow. In contrast to Hsu's experiments, we focus on sliding wear erosion at the flow boundary rather than impact/frictional wear at the flow head. By varying effective gravity from 1g-100g we can tune the pressure exerted by the grains at the boundary without having to change the scale of our apparatus. Using a recently developed depth-averaged, kinetic-energy closure theory for granular flow, we can simultaneously tune the drum rotation rate such that the flow dynamics remain invariant. We can thereby explore how changing the scale of a granular flow, and thus the contact forces of grains on the boundary, controls the rate of rock erosion. Using a small apparatus we can simulate the erosion generated by debris flows several meters deep involving grains up to 10cm in diameter.Our results suggest that sliding wear is the main erosion process, and are consistent with Archard

  14. Study of the Parametric Performance of Solid Particle Erosion Wear under the Slurry Pot Test Rig

    Directory of Open Access Journals (Sweden)

    S.R. More

    2017-12-01

    Full Text Available Stainless Steel (SS 304 is commonly used material for slurry handling applications like pipelines, valves, pumps and other equipment's. Slurry erosion wear is a common problem in many engineering applications like process industry, thermal and hydraulic power plants and slurry handling equipments. In this paper, experimental investigation of the influence of solid particle size, impact velocity, impact angle and solid concentration parameters in slurry erosion wear behavior of SS 304 using slurry pot test rig. In this study the design of experiments was considered using Taguchi technique. A comparison has been made for the experimental and Taguchi technique results. The erosion wear morphology was studied using micro-graph obtained by scanning electron microscope (SEM analysis. At shallow impact angle 30°, the material removal pattern was observed in the form of micro displacing, scratching and ploughing with plastic deformation of the material. At 60° impact angle, mixed type of micro indentations and pitting action is observed. At normal impact angle 90°, the material removal pattern was observed in form of indentation and rounded lips. It is found that particle velocity was the most influence factor than impact angle, size and solid concentration. From this investigation, it can be concluded that the slurry erosion wear is minimized by controlling the slurry flow velocity which improves the service life of the slurry handling equipments. From the comparison of experimental and Taguchi experimental design results it is found that the percentage deviation was very small with a higher correlation coefficient (r2 0.987 which is agreeable.

  15. Effectiveness of resin-based materials against erosive and abrasive enamel wear.

    Science.gov (United States)

    Zhao, Xiaoyi; Pan, Jie; Zhang, Songmei; Malmstrom, Hans S; Ren, Yan-Fang

    2017-01-01

    The objective of this study was to test the effectiveness of resin-based materials against erosive enamel wear under erosive and abrasive challenges by orange juice and tooth brushing. Fifty enamel specimens from third molars were assigned to five groups: ICON resin infiltration with no etching (ICON-NE), ICON resin infiltration with 15 % HCl etching (ICON-AE), Seal & Protect sealant (S&P), Tetric EvoFlow (TEF), and control. Erosive lesions were first created on enamel, then treated with resin-based materials. Erosive and abrasive challenges by orange juice and tooth brushing were repeated after treatments. Erosive wear of the treated areas was measured with 3D scanning microscopy, and data were analyzed using ANOVA and paired t tests. Treatments with ICON, S&P, and TEF created a protective material coating of 4.5 ± 1.9 μm, 44.3 ± 8.1 μm, and 84.6 ± 15.7 μm in thickness on the lesion surfaces, respectively. After 15 cycles of erosive and abrasive challenges, enamel or material losses were 21.9 ± 2.3 μm for control, 24.5 ± 4.0 μm for ICON-NE, 24.6 ± 7.4 μm for ICON-AE, 11.2 ± 4.1 μm for S&P, and 3.9 ± 1.9 μm for TEF, respectively. The protective coatings were completely lost in the ICON infiltration groups but remained intact in both the S&P and TEF groups after erosive and abrasive challenges. In contrast to a resin sealant and a flowable composite, ICON infiltration resin was not effective in protecting enamel surfaces from erosive and abrasive wear. Sealant and flowable composite resin may create protective coatings on eroded enamel surfaces and prevent further tissue loss.

  16. Mimicking and Measuring Occlusal Erosive Tooth Wear with the "Rub&Roll" and Non-contact Profilometry.

    Science.gov (United States)

    Ruben, Jan L; Truin, Gert-Jan; Loomans, Bas A C; Huysmans, Marie-Charlotte D N J M

    2018-02-02

    Chewing, drinking, and occasional tooth grinding will result in physiological tooth wear during a lifetime. Extreme challenges, such as bruxism or habitual chewing on foreign objects, may lead to excessive wear. Recently, the role of erosion in accelerating mechanical tooth wear has been recognized, but the interplay between chemical and mechanical wear processes has not been extensively studied. Our laboratory recently introduced a novel oral wear simulation device, the Rub&Roll, that enables the user to perform wear and loading studies separately or simultaneously in an erosive and/or abrasive environment. This manuscript describes an application of the device: the combined mechanical and erosive loading of extracted human (pre)molars in a simulated chewing movement, with a controlled application of force, velocity, fluid, and time, and the application of non-contact profilometry in visualizing and measuring the resulting wear pattern. The occlusal morphology that was created in the experiment with the highest loading level is very similar to the clinical presentation of erosive wear.

  17. Kinetics of the σ Phase Precipitation in Respect of Erosion-corrosion Wear of Duplex Cast Steel

    Directory of Open Access Journals (Sweden)

    Brodziak-Hyska A.

    2014-03-01

    Full Text Available The examined material comprised two grades of corrosion-resistant cast steel, namely GX2CrNiMoN25-6-3 and GX2CrNiMoCuN25-6-3- 3, used for example in elements of systems of wet flue gas desulphurisation in power industry. The operating conditions in media heated up to 70°C and containing Cl' and SO4 ions and solid particles produce high erosive and corrosive wear.The work proposes an application of the σ phase as a component of precipitation strengthening mechanism in order to increase the functional properties of the material. The paper presents the results of examination of the kinetics of σ phase precipitation at a temperature of 800°C and at times ranging from 30 to 180 minutes. Changes in the morphology of precipitates of the σ phase were determined using the value of shape factor R. Resistance to erosion-corrosion wear of duplex cast steel was correlated with the kinetics of sigma phase precipitating.

  18. Effect of ion implantation on subsequent erosion and wear behavior of solids

    International Nuclear Information System (INIS)

    McHargue, C.J.

    1985-01-01

    The removal of material from a solid surface by mechanical forces is influenced by material properties (hardness, fracture toughness, yield strength, surface free energy) as well as system parameters (force, velocity of loading, environment). Ion implantation can modify many of the material properties either by directly affecting the deformation characteristics or indirectly by affecting the chemical or phase composition at the surface. The various forms of wear and erosion are analyzed to determine the material and system parameters which control material removal. The effects of implantation on these critical parameters are noted and examples of changes in surface topography under various test conditions are discussed. 18 figs

  19. The effect of daily fluoride mouth rinsing on enamel erosive/abrasive wear in situ.

    Science.gov (United States)

    Stenhagen, K R; Hove, L H; Holme, B; Tveit, A B

    2013-01-01

    It is not known whether application of fluoride agents on enamel results in lasting resistance to erosive/abrasive wear. We investigated if one daily mouth rinse with sodium fluoride (NaF), stannous fluoride (SnF(2)) or titanium tetrafluoride (TiF(4)) solutions protected enamel against erosive/abrasive wear in situ (a paired, randomised and blind study). Sixteen molars were cut into 4 specimens, each with one amalgam filling (measurement reference surface). Two teeth (2 × 4 specimens) were mounted bilaterally (buccal aspects) on acrylic mandibular appliances and worn for 9 days by 8 volunteers. Every morning, the specimens were brushed manually with water (30 s) extra-orally. Then fluoride solutions (0.4% SnF(2) pH 2.5; 0.15% TiF(4) pH 2.1; 0.2% NaF pH 6.5, all 0.05 M F) were applied (2 min). Three of the specimens from each tooth got different treatment, and the fourth served as control. At midday, the specimens were etched for 2 min in 300 ml fresh 0.01 M hydrochloric acid and rinsed in tap water. This etch procedure was repeated in the afternoon. Topographic measurements were performed by a white-light interferometer. Mean surface loss (±SD) for 16 teeth after 9 days was: SnF(2) 1.8 ± 1.9 µm, TiF(4) 3.1 ± 4.8 µm, NaF 26.3 ± 4.7 µm, control 32.3 ± 4.4 µm. Daily rinse with SnF(2), TiF(4) and NaF resulted in 94, 90 and 18% reduction in enamel erosive/abrasive wear, respectively, compared with control (p < 0.05). The superior protective effect of daily rinse with either stannous or titanium tetrafluoride solutions on erosive/abrasive enamel wear is promising. Copyright © 2012 S. Karger AG, Basel.

  20. Thin Layer Activation (TLA) Technique Application for Monitoring Corrosion, Erosion and Wear on Industrial Components

    International Nuclear Information System (INIS)

    Hari Suryanto; Sunarhadijoso Soenarjo; Imam Kambali

    2003-01-01

    Thin Layer Activation (TLA) technique is one of high-precision and effective nuclear methods for measurement and monitoring corrosion, erosion and wear on industrial components. This technique was developed by using low current charged particle beam produced from a cyclotron to activate a surface layer of component. In this case only the surface layer in the μm range at the desired parts of the component are activated. The surface activation lets a very low radioactivity concerning to safety aspect but still can be detected and measured well due to specificity and sensitivity of nuclear reaction produced. Some reported experiences on TLA technique have confirmed that the technique is proper fully recommended to be applied in various industries such as automotive, petrochemical, petroleum, power plant, transportation, lubricant oil etc. The measurement and monitoring of corrosion, erosion and wear rates can be remotely and continuously performed, on-line and in-situ, giving a real-time information. By giving a real-time information, TLA technique provides a considerably better estimation of the components lifetimes for any operating condition. The measurement sensitivity of surface loss rate by using this method can reach up to 0.01 μm depends on the type of applications. The application of the TLA technique lets early observation on the damage of the system preventing any disturbance on industrial process, either in the form of accident during the process or that of unscheduled interruption. (author)

  1. Impact of dentifrice abrasivity and remineralization time on erosive tooth wear in vitro.

    Science.gov (United States)

    Buedel, Sarah; Lippert, Frank; Zero, Domenick T; Eckert, George J; Hara, Anderson T

    2018-02-01

    To investigate the in vitro effects of simulated dentifrice slurry abrasivity (L-low, M-medium and H-high) and remineralization time (0, 30, 60 and 120 minutes) on erosive tooth wear. Enamel and root dentin specimens were prepared from bovine incisors (n= 8) and submitted to a cycling protocol including erosion, remineralization at the test times, and brushing with each of the tested slurries, for 5 days. Dental surface loss (SL) was determined by optical profilometry. Data was analyzed using mixed-model ANOVA and Fisher's PLSD tests (alpha= 0.05). SL generally increased along with the increase in slurry abrasive level, with significance dependent upon the specific substrate and remineralization times. H showed the highest SL on both enamel and dentin; remineralization for 30 minutes reduced SL significantly (Pabrasive dentifrice slurries were able to reduce toothbrushing abrasion on both enamel and root dentin. This protection was enhanced by remineralization for all abrasive levels on enamel, but only for L on root dentin. High-risk erosion patients should avoid highly abrasive toothpastes, as remineralization can only partially compensate for their deleterious effects on eroded dental surfaces. Lower abrasive toothpastes are recommended. Copyright©American Journal of Dentistry.

  2. Long-term protective effect of surface sealants against erosive wear by intrinsic and extrinsic acids.

    Science.gov (United States)

    Wegehaupt, Florian J; Tauböck, Tobias T; Sener, Beatrice; Attin, Thomas

    2012-05-01

    To test sealants to prevent erosive tooth wear caused by extrinsic and intrinsic acids under long-term exposition. 144 bovine enamel samples were randomly allocated to twelve groups (1-12). Samples of groups 1, 5 and 9 remained unsealed (positive controls), 2, 6 and 10 were sealed with Silicon Seal Nano Mix and 3, 7 and 11 with Seal&Protect. Groups 4, 8 and 12 were sealed with flowable composite (negative controls). Groups 1-4 were immersed in artificial saliva, 5-8 in hydrochloric acid and groups 9-12 in citric acid for 28 days, respectively. After 1, 2, 4, 7, 11, 14, 21 and 28 days, solutions were renewed and enamel wear was quantified by assignation of (32)P in the solutions. In all immersion solutions, lowest mineral loss was observed for the negative controls whilst highest loss was observed for unsealed positive controls. In artificial saliva and citric acid, the loss from samples sealed with Seal&Protect was not significantly different compared with negative controls whilst loss in groups sealed with Silicon Seal Nano Mix was significantly higher. In hydrochloric acid, loss from samples sealed with Seal&Protect was not different compared with that of negative controls up to 4 days. Except day 1, the mineral loss in the Seal&Protect group was significantly lower compared with that of the Silicon Seal Nano Mix group. The tested resin based surface sealant is able to significantly reduce the erosive demineralisation of enamel caused by hydrochloric and citric acid even under long-term exposition. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Comprehensive study of the abrasive wear and slurry erosion behavior of an expanded system of high chromium cast iron and microstructural modification for enhanced wear resistance

    Science.gov (United States)

    Chung, Reinaldo Javier

    High chromium cast irons (HCCIs) have been demonstrated to be an effective material for a wide range of applications in aggressive environments, where resistances to abrasion, erosion and erosion-corrosion are required. For instance, machinery and facilities used in mining and extraction in Alberta's oil sands suffer from erosion and erosion-corrosion caused by silica-containing slurries, which create challenges for the reliability and maintenance of slurry pumping systems as well as other processing and handling equipment. Considerable efforts have been made to determine and understand the relationship between microstructural features of the HCCIs and their wear performance, in order to guide the material selection and development for specific service conditions with optimal performance. The focus was previously put on a narrow group of compositions dictated by ASTM A532. However, with recent advances in casting technology, the HCCI compositional range can be significantly expanded, which potentially brings new alloys that can be superior to those which are currently employed. This work consists of three main aspects of study. The first one is the investigation of an expanded system of white irons with their composition ranging from 1 to 6 wt.% C and 5 to 45 wt.% Cr, covering 53 alloys. This work has generated wear and corrosion maps and established correlation between the performance and microstructural features for the alloys. The work was conducted in collaboration with the Materials Development Center of Weir Minerals in Australia, and the results have been collected in a database that is used by the company to guide materials selection for slurry pump components in Alberta oil sands and in other mining operations throughout the world. The second part consists of three case studies on effects of high chromium and high carbon, respectively, on the performance of the HCCIs. The third aspect is the development of an approach to enhance the wear resistance of

  4. Protective effects of resin sealant and flowable composite coatings against erosive and abrasive wear of dental hard tissues.

    Science.gov (United States)

    Zhao, Xiaoyi; Pan, Jie; Malmstrom, Hans S; Ren, Yan-Fang

    2016-06-01

    To test the effectiveness of sealant and flowable composite coating on eroded enamel, dentin and cementum under erosive/abrasive challenges in vitro. A total of 108 tissue sections (36 each for enamel, dentin and cementum) from third molars were assigned to three groups: Seal & Protect sealant (S&P), Tetric EvoFlow composite (TEF) and control. Erosive/abrasive lesions were created on each specimen by citric acid and brushing with toothpaste. S&P and TEF were applied to the lesions and subjected to erosive/abrasive cycling included 24 cycles of immersion in citric acid (pH 3.6) for 60min, followed by remineralization for 120min and brushing with toothpastes for 600 strokes at 150g. Erosive wear of materials or dental tissues were measured with 3D scanning microscopy and data were analyzed using ANOVA. Treatments with S&P and TEF created a protective material coating of 42.7±17.8μm and 150.8±9.9μm in thickness, respectively. After 24 cycles of erosive/abrasive challenges, tissue losses were -346.9±37.3μm for enamel, -166.5±26.3μm for dentin and -164.7±18.2μm for cementum in untreated controls, as compared to material losses of -24.4±3.3μm for S&P, and -10.8±4.4μm for TEF, respectively. Both S&P and TEF were effective in protecting enamel, dentin and cementum against erosive tooth wear (pwear than TEF (pabrasive challenges. A thin coating of flowable composite resin 150μm in thickness may provide long-term protection against erosive/abrasive tooth wear. Resin sealant may provide adequate protection for dental hard tissues in short-term and may require repeated applications if long-term protection is desired. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Microstructure and erosive wear behaviors of Ti6Al4V alloy treated by plasma Ni alloying

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Z.X.; Wu, H.R.; Shan, X.L.; Lin, N.M.; He, Z.Y., E-mail: tyuthzy@126.com; Liu, X.P.

    2016-12-01

    Graphical abstract: The Ni modified layers were prepared on the surface of Ti6Al4V substrate by the plasma surface alloying technique. The surface and cross-section morphology, element concentration and phase composition were investigated by thermal field emission scanning electron microscopy (SEM), and glow discharge optical emission spectroscopy (GDOES), X-ray diffraction (XRD), respectively. The cross-section nano-scale hardness of Ni modified layer was measured by nano indenter. The results showed that Ni modified layers exhibited triple layers structure and continuous gradient distribution of the concentration. From the surface to the matrix, they were 2 μm Ni deposition layer, 8 μm Ni-rich alloying layer including the phases of Ni{sub 3}Ti, NiTi, Ti{sub 2}Ni, AlNi{sub 3} and 24 μm Ni-poor alloying layer forming the solid solution of nickel. With increasing of the thickness of Ni modified layer, the microhardness increased first, reached the climax, then gradient decreased. The erosion tests were performed on the surface of the untreated and treated Ti6Al4V sample using MSE (Micro-slurry-jet Erosion) method. The experiment results showed that the wear rate of every layer showed different value, and the Ni-rich alloying layer was the lowest. The strengthening mechanism of Ni modified layer was also discussed. - Highlights: • The Ni modified layers were prepared by the plasma surface alloying technique. • Triple layers structure was prepared. • Using Micro-slurry-jet Erosion method. • The erosion rate of Ni modified layer experienced the process of descending first and then ascending. • Improvement of erosion resistance performance of Ni-rich alloying layer was prominent. The wear mechanism of Ni modified layer showed micro-cutting wearing. - Abstract: The Ni modified layers were prepared on the surface of Ti6Al4V substrate by the plasma surface alloying technique. The surface and cross-section morphology, element concentration and phase composition

  6. Protective Effect of Adhesive Systems associated with Neodymium-doped Yttrium Aluminum Garnet Laser on Enamel Erosive/Abrasive Wear.

    Science.gov (United States)

    Crastechini, Erica; Borges, Alessandra B; Becker, Klaus; Attin, Thomas; Torres, Carlos Rg

    2017-10-01

    This study evaluated the efficacy of self-etching adhesive systems associated or not associated with the neodymium-doped yttrium aluminum garnet (Nd:YAG) laser on the protection against enamel erosive/abrasive wear. Bovine enamel specimens were demineralized with 0.3% citric acid (5 minutes). The samples were randomly assigned to eight groups (n = 20): SB - Single Bond Universal (3M/ESPE); SB+L - Single Bond Universal + laser (80 mJ/10 Hz); FB - Futurabond U (Voco); FB+L -Futurabond U + laser; GEN - G-aenial bond (GC); GEN+L -G-aenial bond + laser; L - laser irradiation; and C - no treatment. The laser was applied before light curing. The samples were subjected to erosive/abrasive challenges (0.3% citric acid - 2 minutes and tooth brushing four times daily for 5 days). Enamel surface loss was recovered profilometrically by comparison of baseline and final profiles. The adhesive layer thickness, retention percentage of the protective layer, and microhardness of cured adhesive were measured. Data were analyzed using one-way analysis of variance and Tukey's test (5%). There were significant differences for all parameters (p = 0.0001). Mean values ± SD and results of the Tukey's test were: Surface wear: GEN - 4.88 (±1.09)a, L - 5.04 ± 0.99)a, FB - 5.32 (±0.93)ab, GEN + L - 5.46 (±1.27)abc, SB + L - 5.78 (±1.12)abc, FB + L - 6.23 (±1.25)bc, SB - 6.35 (±1.11)c, and C - 6.46 (±0.61)c; layer thickness: GEN - 15.2 (±8.63)c, FB - 5.06 (±1.96)a, GEN + L - 13.96 (±7.07)bc, SB + L - 4.24 (±2.68)a, FB + L - 9.03 (±13.02)abc, and SB - 7.49 (±2.80)ab; retention: GEN - 68.89 (±20.62)c, FB - 54.53 (±24.80)abc, GEN + L - 59.90 (±19.79)abc, SB + L - 63.37 (±19.30)bc, FB + L - 42.23 (±17.68) a, and SB - 47.78 (±18.29)ab; microhardness: GEN - 9.27 (±1.75)c; FB - 6.99 (±0.89)b; GEN + L - 6.22 (±0.87)ab; SB + L - 15.48 (±2.51)d; FB + L - 10.67 (±1.58)c; SB - 5.00 (±1.60)a. The application of Futurabond U and G-aenial bond on enamel surface, as well as the Nd

  7. Abrasive-Erosive Wear of Thermally Sprayed Coatings from Experimental and Commercial Cr3C2-Based Powders

    Science.gov (United States)

    Sarjas, Heikki; Surzhenkov, Andrei; Juhani, Kristjan; Antonov, Maksim; Adoberg, Eron; Kulu, Priit; Viljus, Mart; Traksmaa, Rainer; Matikainen, Ville; Vuoristo, Petri

    2017-12-01

    In this paper, high-velocity oxy-fuel sprayed coatings from experimental Cr3C2-Ni powder produced by mechanically activated thermal synthesis and disintegrator milling are compared with coatings from commercial Cr3C2-NiCr powder under room- and elevated-temperature abrasive-erosive wear (AEW) conditions. In a room-temperature AEW test, the coating made from the experimental powder had wear rates that were 1.1-5.3 times higher than the coating from the commercial powder; this difference was the lowest at the highest impact velocity (80 m s-1). Under AEW tests at elevated temperature (300 and 550 °C), the coating made from the experimental powder exhibited wear rates that were 1.2-2.8 times higher in comparison with that made from the commercial powder, but this difference was smaller under an oblique impact angle (30°) and higher temperature conditions. The reasons for the lower resistance against AEW of the coating made from the experimental powder were found to be its lower ability to resist plastic indentation and deformation as well as lower indentation fracture toughness at room temperature, weaker bonding between the matrix and reinforcement and probably lower mechanical properties as well as unfavourable residual stresses at elevated temperatures.

  8. Effect of casein phosphopeptide-amorphous calcium phosphate and acidulated phosphate fluoride gel on erosive enamel wear

    Directory of Open Access Journals (Sweden)

    Maryam HajeNorouz Ali Tehrani

    2011-01-01

    Conclusions: We concluded that although either CPP-ACP or APF can protect enamel against wear, their combination provides significant enamel wear reduction. These findings would lead to new strategies for the clinical management of tooth wear.

  9. Chemically Derived Dense Alumina-Zirconia Composites for Improved Mechanical and Wear Erosion Properties

    Science.gov (United States)

    1998-01-01

    As a result of this funded project high purity Zirconia-Toughened Alumina (ZTA) ceramic powders with and without yttria were produced using metal alkoxide precursors. ZTA ceramic powders with varying volume percents of zirconia were prepared (7, 15, and 22%). Aluminum tri-sec butoxide, zirconium propoxide, and yttrium isopropoxide were the reagents used. Synthesis conditions were varied to control the hydrolysis and the aging conditions for the sol to gel transition. FTIR analysis and rheological characterization were used to follow the structural evolution during the sol to gel transition. The greater extent of hydrolysis and the build-up of structure measured from viscoelastic properties were consistent. Heat treatment was conducted to produce submicron grain fully crystalline ZTA ceramic powders. This improved materials should have enhanced properties such strength, toughness, and wear resistance for advanced structural applications, for example engine components in high technology aerospace applications.

  10. Analytical approximation of the erosion rate and electrode wear in micro electrical discharge machining

    International Nuclear Information System (INIS)

    Kurnia, W; Tan, P C; Yeo, S H; Wong, M

    2008-01-01

    Theoretical models have been used to predict process performance measures in electrical discharge machining (EDM), namely the material removal rate (MRR), tool wear ratio (TWR) and surface roughness (SR). However, these contributions are mainly applicable to conventional EDM due to limits on the range of energy and pulse-on-time adopted by the models. This paper proposes an analytical approximation of micro-EDM performance measures, based on the crater prediction using a developed theoretical model. The results show that the analytical approximation of the MRR and TWR is able to provide a close approximation with the experimental data. The approximation results for the MRR and TWR are found to have a variation of up to 30% and 24%, respectively, from their associated experimental values. Since the voltage and current input used in the computation are captured in real time, the method can be applied as a reliable online monitoring system for the micro-EDM process

  11. Efficacy of TiF4 and NaF varnish and solution: a randomized in situ study on enamel erosive-abrasive wear.

    Science.gov (United States)

    Levy, Flávia Mauad; Rios, Daniela; Buzalaf, Marília A R; Magalhães, Ana Carolina

    2014-05-01

    This in situ/ex vivo study analysed the anti-erosive/abrasive effect of TiF4 and NaF varnish and solution on enamel wear. Twelve subjects took part in this study which was performed in three periods (phases) with the duration of 5 days each. Each two human enamel specimens per subject were pretreated with experimental NaF varnish or solution (phase A), experimental-TiF4 varnish or solution (phase B) and placebo varnish or untreated control (phase C). The specimens were worn in palatal appliances; one enamel specimen, from each treatment, was subjected to erosion (ERO; cola soft drink, 4 × 90 s/day), and the other specimen was subjected to erosion plus abrasion (ERO + ABR; tooth brushing, 2 × 10 s/day). The tooth wear was quantified by a contact profilometer (micrometre) and analysed using two-way repeated measures ANOVA and Bonferroni's test (n = 12 subjects, p wear (around 25 %) significantly compared to the control and placebo varnish. There were no significant differences among the fluoride formulations and between the conditions ERO and ERO + ABR. Therefore, it can be concluded that TiF4 has the same protective potential as NaF formulations to reduce human enamel wear under this experimental in situ model. In vitro studies have indicated a better anti-erosive/abrasive effect of TiF4 compared to NaF varnish. The present in situ study does not support the previous findings. Therefore, any of the tested professional fluoride varnishes in principle could be able to partially reduce enamel wear.

  12. The role of fluoride and casein phosphopeptide/amorphous calcium phosphate in the prevention of erosive/abrasive wear in an in vitro model using hydrochloric acid.

    Science.gov (United States)

    Wegehaupt, Florian J; Attin, T

    2010-01-01

    To investigate the effect of various fluoride compounds and casein phosphopeptide/amorphous calcium phosphate (CPP-ACP) on the reduction of erosive/abrasive tooth wear. Forty enamel samples were prepared from bovine lower incisors, stratified and allocated to 4 groups (1-4). Samples in group 1 remained untreated and served as negative controls. The test samples were treated for 2 min/day as follows: group 2 amine/sodium fluoride gel (pH 4.8; 12,500 ppm), group 3 sodium fluoride gel (pH 7.1; 12,500 ppm) and group 4 CPP-ACP-containing mousse. De- and remineralization cycling was performed for 20 days with 6 erosive attacks for 20 s with HCl (pH 3.0) per day. Samples were stored in artificial saliva between cycles and overnight. Toothbrushing (15 s; 60 strokes/min; load 2.5 N) with a toothpaste slurry was performed each day before the first and 1 h after the last erosive exposure. Tooth wear was measured by comparing baseline surface profiles with the corresponding posttreatment profiles. Tooth wear was significantly reduced in groups 2 and 3 compared with group 1, while the enamel loss of group 4 was not significantly lower compared to the negative control group 1. Between the fluoride groups 2 and 3, no significant difference in tooth wear was recorded. Erosive/abrasive tooth wear under the conditions used could be reduced significantly by the daily application of fluoride gels, irrespective of the fluoride compound, while the application of CPP-ACP-containing mousse was less effective. Copyright 2010 S. Karger AG, Basel.

  13. Multifactorial logistic regression analysis of factors associated with the incidence of erosive tooth wear among adults at different ages in Tokyo.

    Science.gov (United States)

    Kitasako, Yuichi; Sasaki, Y; Takagaki, T; Sadr, A; Tagami, J

    2017-11-01

    The aim of this study was to evaluate factors associated with the incidence of erosive tooth wear (ETW) among adults at different ages in Tokyo using multifactorial logistic regression analysis. The study sample consisted of a total of 1108 subjects aged 15 to 89 years in Tokyo, Japan. Two examiners evaluated ETW in a full-mouth recording. The subjects were asked to complete a self-administered daily diet, habit, and health condition questionnaire. Subjects who had frequent acid consumption or gastric reflux and at least one tooth with initial enamel wear were placed in the ETW-positive group, and the remainder of the subjects was placed in the ETW-negative group. Logistic regression analyses were carried out to identify factors collectively associated with ETW. Logistic regression analysis showed that greater frequencies of carbonated or sports drink consumption were associated with higher incidence of ETW for all age groups except for 70-89 years. Adults in the 30-39-year group who reported suffering from heartburn were about 22.3 times more likely to develop ETW, while 40-49-year adults who had repeated vomiting were about 33.5 times more likely to exhibit ETW compared with those who did not experience vomiting. Age-specific dietary habits were clearly observed among adults at different ages in Tokyo, and there were significant differences in intrinsic and extrinsic factors between ETW-positive and ETW-negative groups for each age group. Both greater frequency of carbonated and sports drink consumption were associated with higher incidence of ETW among adults at different ages in Tokyo.

  14. Macro- and microtopographical examination and quantification of CAD-CAM composite resin 2- and 3-body wear.

    Science.gov (United States)

    Stöckl, Carolin; Hampe, Rüdiger; Stawarczyk, Bogna; Haerst, Miriam; Roos, Malgorzata

    2018-04-05

    The selection of an appropriate restorative material based on wear behavior is important for the long-term success of a dental restoration. For computer-aided design and computer-aided manufacturing (CAD-CAM) composite resins, information about their wear resistance and wear mechanism is scarce. The purpose of this in vitro study was to compare the 2- and 3-body wear of CAD-CAM composite resins with that of lithium disilicate ceramic and to develop analysis software. Flat specimens were prepared from the following CAD-CAM composite resins: Cerasmart (CS), SHOFU Block HC (SH), Katana Avencia (KA), Brilliant Crios (BC), an experimental composite resin (EXP), and lithium disilicate ceramic IPS e.max CAD (REF). The specimens underwent 2-body wear (50 N, 5/55°C, 400 000 cycles) opposed by human enamel antagonists. Specimen wheels were prepared with each material on each wheel for 3-body wear with a millet slurry (15 N, 15% slip, 200 000 cycles). All specimens were digitized by using a dedicated laser scanner. Analysis software was developed to calculate macrotopographical examination of volume loss. The microtopography of the surfaces was examined by using scanning electron microscopy. For data analysis, the Kruskal-Wallis test with the Tukey-Kramer post hoc test and the 1-sample Wilcoxon test were used (α=.05). After 2-body wear simulation, SH and KA presented higher volume loss than the other CAD-CAM materials. For 3-body wear, REF had lower volume loss than CS, SH, or BC. In addition, BC led to higher volume loss than EXP. The patterns of 2- and 3-body wear were different. The ceramic showed good global wear resistance. The volume loss of the CAD-CAM composite resins differed and depended on the material. The 2- and 3-body wear test methods tended to differ with regard to volume loss. Examination of the worn surfaces revealed different mechanisms acting in 2- and 3-body wear test. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry

  15. Tooth -Wear Lesions Among Patients Attending Tertiary Hospital in ...

    African Journals Online (AJOL)

    Tooth wear manifest in the form of abrasion, attrition, erosion and abfraction and can affect the quality of life of the sufferer. This was a prospective study of patients who ... We recommend oral hygiene advice, dietary counseling and regular dental examination for early detection. Key words: Tooth wear, lesion, prospective, ...

  16. Assessment of Erosion Resistance of Coated Polymer Matrix Composites for Propulsion Applications

    Science.gov (United States)

    Miyoshi, Kazuhisa; Sutter, James K.; Horan, Richard A.; Naik, Subhash K.; Cupp, Randall J.

    2004-01-01

    The erosion behavior of tungsten carbide-cobalt (WC-Co) coated and uncoated polymer matrix composites (PMCs) was examined with solid particle impingement using air jets. Erosion tests were conducted with Arizona road dust impinging at 20 degrees, 60 degrees, and 90 degrees angles at a velocity of 229 meters per second at both 294 and 366 K. Noncontact optical profilometry was used to measure the wear volume loss. Results indicate that the WC-Co coating enhanced erosion resistance and reduced erosion wear volume loss by a factor of nearly 2. This should contribute to longer wear lives, reduced related breakdowns, decreased maintenance costs, and increased product reliability.

  17. Tooth wear

    Directory of Open Access Journals (Sweden)

    Tušek Ivan

    2014-01-01

    Full Text Available Tooth wear is the loss of dental hard tissue that was not caused by decay and represents a common clinical problem of modern man. In the etiology of dental hard tissue lesions there are three dominant mechanisms that may act synergistically or separately:friction (friction, which is caused by abrasion of exogenous, or attrition of endogenous origin, chemical dissolution of dental hard tissues caused by erosion, occlusal stress created by compression and flexion and tension that leads to tooth abfraction and microfracture. Wear of tooth surfaces due to the presence of microscopic imperfections of tooth surfaces is clinically manifested as sanding veneers. Tribology, as an interdisciplinary study of the mechanisms of friction, wear and lubrication at the ultrastructural level, has defined a universal model according to which the etiopathogenesis of tooth wear is caused by the following factors: health and diseases of the digestive tract, oral hygiene, eating habits, poor oral habits, bruxism, temporomandibular disorders and iatrogenic factors. Attrition and dental erosion are much more common in children with special needs (Down syndrome. Erosion of teeth usually results from diseases of the digestive tract that lead to gastroesophageal reflux (GER of gastric juice (HCl. There are two basic approaches to the assessment of the degree of wear and dental erosion. Depending on the type of wear (erosion, attrition, abfraction, the amount of calcium that was realised during the erosive attack could be determined qualitatively and quantitatively, or changes in optical properties and hardness of enamel could be recorded, too. Abrasion of teeth (abrasio dentium is the loss of dental hard tissue caused by friction between the teeth and exogenous foreign substance. It is most commonly provoked by prosthetic dentures and bad habits, while its effect depends on the size of abrasive particles and their amount, abrasive particle hardness and hardness of tooth

  18. Endocardial silicone lead wear: description of tribological phenomena on the basis of microscopic examination of removed leads. Preliminary report.

    Science.gov (United States)

    Małecka, Barbara; Ząbek, Andrzej; Ciaś, Andrzej; Stępiński, Janusz; Kutarski, Andrzej; Rońda, Jacek; Lelakowski, Jacek; Małecki, Janusz

    2014-01-01

    The passage of a lead in tissues and in the cardiovascular system depends on the implantation technique. The structure of the leads, which is a combination of two or more materials, triggers their wear. Breakage of the external pacemaker (PM) lead insulation causes unsealing of the lead and exposure of its internal spaces, which can be the anchor of lead-dependent infective endocarditis (LDIE). In the case of implantable cardioverter-defibrillator (ICD) leads, damage to external insulation isthe cause of externalisation of the cable. To describe endocardial lead abrasion as a tribological phenomenon resulting from rubbing the leads against each other in the mechanism of polymer on polymer friction, and other mechanisms associated with lead structure i.e. polymer on metal friction. Twenty-two leads were extracted from ten patients (three women) aged 66.5 ± 13.4 years. In all cases, the reason for lead removal was infection — in 80% LDIE. The PM (one ICD) two- and three-lead systems, all with silicone insulation, were aged 3–25, mean 8.3 years. The destroyed polymer insulation was examined by optical and scanning electron microscopy. The site of damage was defined as the length of the lead from its distal end. This lead segment motion was analysed on chest scopy performed prior to the removal procedure. In this way, three sites of lead damage were distinguished: intracardiac, intravenous, and intrapocket. Tribological wear was observed on the polymer-metal interface and between the leads. The following characteristics were recorded: the type of PM or ICD system in which the extracted leads worked, the lead dwell time,and the lead model. Scanning electron examinations showed that in all cases lead insulation had undergone tribological failure. In all samples, the image of fatigue wear was recorded. In all examined places, we found evidence that adhesive wear was present with the transfer of material to the edges of friction zones and/or to friction partners. In

  19. Proceedings of the Tri-Service Gun Tube Wear and Erosion Symposium, ARRADCOM, Dover, NJ, 29-31 March 1977

    Science.gov (United States)

    1977-03-01

    and a 300 ship magazine capacity. It was assumed that one day is required for re-arming. Guiline refers to the number of ship days available on the...tubes in the US tank fleet. This sample consisted of over 2% of the total tube population and was taken from tubes in service in the Continental United... population , an auxillary data file, ordered on reported vehicle (tank) serial numbers, was examined. The vehicle serial number is usually reported with the

  20. Protection From Dental Erosion: All Fluorides are Not Equal.

    Science.gov (United States)

    Faller, Robert V; Noble, Warden H

    2018-03-01

    All fluoride sources help strengthen teeth against bacterial acids that cause caries. However, excessive exposure to dietary acids, which can result in dental erosion, presents a more aggressive level of challenge compared to caries. Despite the fact that almost all toothpastes contain fluoride, both the incidence and prevalence of dental erosion appear to be on the rise. This article: (1) describes key differences between caries and dental erosion and the ability of different fluoride sources to help prevent erosion; (2) discusses the importance of the evaluation of patients for dental erosion at the earliest stages using the Basic Erosive Wear Examination scoring system to help assess and educate patients; and (3) provides evidence-based information for making specific recommendations to patients with dental erosion. The objective of this article is to assess the comparative ability of fluoride agents to protect against dental erosion. Though all fluorides are able to help strengthen teeth against cariogenic acids, not all available sources of fluoride provide the same level of erosion protection. Daily use of a stabilized stannous fluoride dentifrice has been shown to provide the most effective means of protecting teeth against the increasing risk of dental erosion and erosive tooth wear.

  1. Friction, wear, and erosion atlas

    CERN Document Server

    Budinski, Kenneth G

    2013-01-01

    "Fundamental aspects of concepts are explained clearly and simply…[and] are supported by illustrations and images of worn surfaces. In addition the book contains a number of appendices, which provide useful engineering information related to tribology."-Raymond G. Bayer, Tribology Consultant, USA

  2. Understanding Buyer Sypplier Relationship in The Kids Wear Industry in India-Examining The Role of Various Constructs

    OpenAIRE

    Kasat, Arpit

    2008-01-01

    This study investigates the buyer supplier relationships and the role of various constructs in the kids wear market in India. It focuses on the budding unorganized segment of the kids wear industry. The purpose of the study is to analyze the changes within the industry and its effects on the unorganized segment. It primarily concentrates on the growing importance of the buyer supplier relationship in this sector and factors contributing to strengthen it. This paper aims to contribute to the e...

  3. Soft drink, software and softening of teeth: a case report of tooth wear in the mixed dentition due to a combination of dental erosion and attrition

    NARCIS (Netherlands)

    Gambon, D.L.; Brand, H.S.; Nieuw Amerongen, A.V.

    2010-01-01

    This case report describes a 9-year-old boy with severe tooth wear as a result of drinking a single glass of soft drink per day. This soft drink was consumed over a period of one to two hours, while he was gaming intensively on his computer. As a result, a deep bite, enamel cupping, sensitivity of

  4. Metallographic examinations of the wear-marks on fuel pins of the KNK II/2 fuel assembly NY-308

    International Nuclear Information System (INIS)

    Patzer, G.

    1987-12-01

    On the fuel pins and pin spacers of the fuel assembly NY-308 of the second core of KNK II pronounced wear marks had been found in the area of the contact points. In order to determine the exact form of the marks, metallographic investigations were performed on two test pieces of fuel pins in the Hot Cells of the KfK Karlsruhe. It was found that the wear marks did show the already observed stratified structure. Next to the unchanged cladding area there is a peripheral zone with modified grain structure, followed by a layer of moved material and finally there is a flake-like zone of accumulated cladding material at the lower end of the wear marks. Longitudinal cuts do not show grain deformations, which could indicate axial friction forces between pin and spacer. The wear marks are rapidly dropping to their maximum depth at the ends and the depth shows a relatively uniform pattern between both. The findings are confirming the picture, that a stirring movement of the fuel pins took place, which caused adhesive wear [de

  5. A preliminary examination of neurocognitive performance and symptoms following a bout of soccer heading in athletes wearing protective soccer headbands.

    Science.gov (United States)

    Elbin, R J; Beatty, Amanda; Covassin, Tracey; Schatz, Philip; Hydeman, Ana; Kontos, Anthony P

    2015-01-01

    This study compared changes in neurocognitive performance and symptom reports following an acute bout of soccer heading among athletes with and without protective soccer headgear. A total of 25 participants headed a soccer ball 15 times over a 15-minute period, using a proper linear heading technique. Participants in the experimental group completed the heading exercise while wearing a protective soccer headband and controls performed the heading exercise without wearing the soccer headband. Neurocognitive performance and symptom reports were assessed before and after the acute bout of heading. Participants wearing the headband showed significant decreases on verbal memory (p = 0.02) compared with the no headband group, while the no headband group demonstrated significantly faster reaction time (p = 0.03) than the headband group following the heading exercise. These findings suggest that protective soccer headgear likely does not mitigate the subtle neurocognitive effects of acute soccer heading.

  6. Examining the physical meaning of the bank erosion coefficient used in meander migration modeling

    Science.gov (United States)

    Constantine, Candice R.; Dunne, Thomas; Hanson, Gregory J.

    2009-05-01

    Widely used models of meander evolution relate migration rate to vertically averaged near-bank velocity through the use of a coefficient of bank erosion ( E). In applications to floodplain management problems, E is typically determined through calibration to historical planform changes, and thus its physical meaning remains unclear. This study attempts to clarify the extent to which E depends on measurable physical characteristics of the channel boundary materials using data from the Sacramento River, California, USA. Bend-average values of E were calculated from measured long-term migration rates and computed near-bank velocities. In the field, unvegetated bank material resistance to fluvial shear ( k) was measured for four cohesive and noncohesive bank types using a jet-test device. At a small set of bends for which both E and k were obtained, we discovered that variability in k explains much of the variability in E. The form of this relationship suggests that when modeling long-term meander migration of large rivers, E depends largely on bank material properties. This finding opens up the possibility that E may be estimated directly from field data, enabling prediction of meander migration rates for systems where historical data are unavailable or controlling conditions have changed. Another implication is that vegetation plays a limited role in affecting long-term meander migration rates of large rivers like the Sacramento River. These hypotheses require further testing with data sets from other large rivers.

  7. Wear Resistance of Sintered Composite Hardfacings under Different Abrasive Wear Conditions

    OpenAIRE

    SIMSON, Taavi; KULU, Priit; SURŽENKOV, Andrei; TARBE, Riho; GOLJANDIN, Dmitri; TARRASTE, Marek; VILJUS, Mart; TRAKSMAA, Rainer

    2017-01-01

    The article focuses on vacuum liquid phase sintered (PM) composite hardfacings and their behaviour under different abrasive wear conditions. Hardfacings studied contained 30 – 50 vol % fine, coarse or multimodal (fine and coarse) hardmetal reinforcement. For wear resistance studies, we used the Abrasive Rubber Wheel Wear (ARWW) test as a three-body abrasive wear test, the Abrasive Wheel Wear (AWW) test as a two-body abrasive wear test and the Abrasive-Impact Erosion wear (AIEW) test as an abr...

  8. Wear Resistance of Sintered Composite Hardfacings under Different Abrasive Wear Conditions

    Directory of Open Access Journals (Sweden)

    Taavi SIMSON

    2017-08-01

    Full Text Available The article focuses on vacuum liquid phase sintered (PM composite hardfacings and their behaviour under different abrasive wear conditions. Hardfacings studied contained 30 – 50 vol % fine, coarse or multimodal (fine and coarse hardmetal reinforcement. For wear resistance studies, we used the Abrasive Rubber Wheel Wear (ARWW test as a three-body abrasive wear test, the Abrasive Wheel Wear (AWW test as a two-body abrasive wear test and the Abrasive-Impact Erosion wear (AIEW test as an abrasive-erosive wear test. Tested materials were compared to Hardox 400 steel and CDP112 wear plate (Castolin Eutectic® Ltd.. It was found that under three-body abrasion conditions (ARWW test hardfacings with high content of spehrical coarse reinforcement are suitable; their wear resistance is about two times higher than that of unreinforced hardfacings. Under two-body abrasive wear (AWW test, hardfacings with a high content of coarse reinforcement are recommended; their wear resistance is up to eight times higher than that of unreinforced hardfacings from the figures and graphs mentioned in the text. Under abrasive-erosive wear (AIEW test, unreinforced ductile materials are recommended; they have two to three times higher wear resistance than composite hardfacings reinforced with fine or multimodal reinforcement.DOI: http://dx.doi.org/10.5755/j01.ms.23.3.16323

  9. Tooth wear and associated risk factors in a sample of Australian primary school children.

    Science.gov (United States)

    Fung, A; Brearley Messer, L

    2013-06-01

    Anecdotally, tooth wear is increasing, perhaps attributable to diet. The irreversible surface loss may result in sensitivity and loss of form and function. Little data exist on the prevalence of tooth wear in Australian children. This study investigated consumption of potentially erosive foods and drinks, examining the prevalence, distribution of tooth wear and associations in a sample of children. Parents of 350, 6-12-year-olds reported their child's oral hygiene, dietary intake, medical and dental histories; 154 children (subsample) were examined. Associations were studied with single and multivariable analyses. Tooth wear was parentally reported for 17% (59 children of the study population) and observed in 66% (102 of the subsample), particularly affecting primary teeth. Significant risk factors for parentally reported tooth wear were: consuming 2-4 cups soft drink/day (OR = 9.52), citrus flavoured sweets/gums ≥1/day (5.10), citrus fruits 1-2/wk (4.28); tooth grinding (5.32); medical condition present (2.48); male gender (2.80). Drinking 2-4 cups fruit juice/day was a significant risk factor for both parentally reported (3.23) and observed tooth wear (3.97). Tooth wear appeared under-reported as some parents were unaware their child's teeth were affected. Significant risk factors for tooth wear were identifiable from children's histories. Risk factors should be addressed early so that tooth wear in the primary dentition does not affect permanent teeth. © 2013 Australian Dental Association.

  10. Dental erosion: causes, diagnostics and treatment.

    Directory of Open Access Journals (Sweden)

    Cecilia Sosa-Puente

    2014-12-01

    Full Text Available Despite being a commonly studied topic, it is difficult to find studies which explain the problem of dental erosion. For this article, literature was analyzed to find information on the agents which trigger dental erosion, the main diagnosis methods, the most common treatments used nowadays and the interrelationship with dental materials. The etiology of dental erosion is multifactorial, including acids, eating disorders and gastro-esophageal reflux. However, biological factors such as saliva or habits also play a part in the establishment of this condition. In order to establish a reliable diagnosis, clinical appearance becomes decisive. The Basic Index Erosive Wear Examination (BEWE, created in 2008, is an auxiliary diagnosis tool for assessing the status and progress of the erosion. Treatment should be linked to the eradication of the causative agent and it can range from simple observational monitoring of slightly affected teeth to the placement of total crowns in the most severe cases, but this will depend entirely on the extent, severity, symptoms and type of dentition. Regarding dental materials used in the treatment of eroded parts, there are glass ionomer and composite; the latter presents the greatest resistance to biodegradation when interacting with acids. Glass ionomers are the most vulnerable material while resin is seen as the most resistant. In conclusion, dental erosion has become an issue of great importance in the dental practice because of its serious impact on dental structures. Consequently, it is ranked among the most important dental disorders in the present day.

  11. Absolute Density Calibration Cell for Laser Induced Fluorescence Erosion Rate Measurements

    Science.gov (United States)

    Domonkos, Matthew T.; Stevens, Richard E.

    2001-01-01

    Flight qualification of ion thrusters typically requires testing on the order of 10,000 hours. Extensive knowledge of wear mechanisms and rates is necessary to establish design confidence prior to long duration tests. Consequently, real-time erosion rate measurements offer the potential both to reduce development costs and to enhance knowledge of the dependency of component wear on operating conditions. Several previous studies have used laser-induced fluorescence (LIF) to measure real-time, in situ erosion rates of ion thruster accelerator grids. Those studies provided only relative measurements of the erosion rate. In the present investigation, a molybdenum tube was resistively heated such that the evaporation rate yielded densities within the tube on the order of those expected from accelerator grid erosion. This work examines the suitability of the density cell as an absolute calibration source for LIF measurements, and the intrinsic error was evaluated.

  12. Sliding wear resistance of iron aluminides

    Indian Academy of Sciences (India)

    Unknown

    severe wear and erosion applications include cobalt- based alloys, high manganese stainless steels, and other chromium containing alloys. There is considerable inte- rest in replacing cobalt-based alloys for erosion resistance in nuclear power applications because of the problems with exposure of maintenance workers to ...

  13. Saliva and dental erosion

    Directory of Open Access Journals (Sweden)

    Marília Afonso Rabelo Buzalaf

    2012-10-01

    Full Text Available Dental erosion is a multifactorial condition. The consideration of chemical, biological and behavioral factors is fundamental for its prevention and therapy. Among the biological factors, saliva is one of the most important parameters in the protection against erosive wear. Objective: This review discusses the role of salivary factors on the development of dental erosion. Material and Methods: A search was undertaken on MeDLINe website for papers from 1969 to 2010. The keywords used in the research were "saliva", "acquired pellicle", "salivary flow", "salivary buffering capacity" and "dental erosion". Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party. Results: Several characteristics and properties of saliva play an important role in dental erosion. Salivary clearance gradually eliminates the acids through swallowing and saliva presents buffering capacity causing neutralization and buffering of dietary acids. Salivary flow allows dilution of the acids. In addition, saliva is supersaturated with respect to tooth mineral, providing calcium, phosphate and fluoride necessary for remineralization after an erosive challenge. Furthermore, many proteins present in saliva and acquired pellicle play an important role in dental erosion. Conclusions: Saliva is the most important biological factor affecting the progression of dental erosion. Knowledge of its components and properties involved in this protective role can drive the development of preventive measures targeting to enhance its known beneficial effects.

  14. Saliva and dental erosion

    Science.gov (United States)

    BUZALAF, Marília Afonso Rabelo; HANNAS, Angélicas Reis; KATO, Melissa Thiemi

    2012-01-01

    Dental erosion is a multifactorial condition. The consideration of chemical, biological and behavioral factors is fundamental for its prevention and therapy. Among the biological factors, saliva is one of the most important parameters in the protection against erosive wear. Objective This review discusses the role of salivary factors on the development of dental erosion. Material and Methods A search was undertaken on MEDLINE website for papers from 1969 to 2010. The keywords used in the research were "saliva", "acquired pellicle", "salivary flow", "salivary buffering capacity" and "dental erosion". Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party. Results Several characteristics and properties of saliva play an important role in dental erosion. Salivary clearance gradually eliminates the acids through swallowing and saliva presents buffering capacity causing neutralization and buffering of dietary acids. Salivary flow allows dilution of the acids. In addition, saliva is supersaturated with respect to tooth mineral, providing calcium, phosphate and fluoride necessary for remineralization after an erosive challenge. Furthermore, many proteins present in saliva and acquired pellicle play an important role in dental erosion. Conclusions Saliva is the most important biological factor affecting the progression of dental erosion. Knowledge of its components and properties involved in this protective role can drive the development of preventive measures targeting to enhance its known beneficial effects. PMID:23138733

  15. Relationship between food habits and tooth erosion occurrence in Malaysian University students.

    Science.gov (United States)

    Manaf, Zahara Abdul; Lee, Mei Tee; Ali, Nor Hazirah Muhammad; Samynathan, Selvamary; Jie, Ying Phor; Ismail, Noor Hasnani; Bibiana Hui Ying, Yong; Wei Seng, Yeo; Yahya, Nurul Asyikin

    2012-04-01

    Tooth erosion is a growing dental problem; however, the role of diet in the aetiology of tooth erosion is unclear. A cross-sectional study was conducted to determine the association between tooth erosion occurrence and the consumption of acidic foods and drinks among undergraduate university students. A total of 150 undergraduate students (33 males and 117 females) aged 19 to 24 years at Universiti Kebangsaan Malaysia participated in this study. The Basic Erosive Wear Examination was used to assess the occurrence of tooth erosion. Information regarding dental hygiene practices, usual dietary habits, and consumption of acidic foods and drinks was obtained through a structured questionnaire. In all, 68% of subjects had tooth erosion. Subjects who reported having received information about healthy eating were less likely to have tooth erosion (χ(2) [1, N = 150] = 7.328, P = 0.007). The frequencies of milk (OR = 0.29, 95% CI = 0.13-0.67) and tea/coffee (adjusted OR = 0.42, 95% CI = 0.19-0.95) consumption were negatively associated with tooth erosion. Dental hygiene practice, the frequency and amount of acidic food and drink intake, and body mass index classification were not significantly associated with the risk of tooth erosion (P > 0.05). A high prevalence of tooth erosion was observed among this group of students. Preventive measures, such as dietary advice and increased consumption of milk at a younger age, may reduce the occurrence of tooth erosion among this age group.

  16. Eye Wear

    Science.gov (United States)

    Eye wear protects or corrects your vision. Examples are Sunglasses Safety goggles Glasses (also called eyeglasses) Contact ... jobs and some sports carry a risk of eye injury. Thousands of children and adults get eye ...

  17. A CFD-Based Study of the Feasibility of Adapting an Erosion Burner Rig for Examining the Effect of CMAS Deposition Corrosion on Environmental Barrier Coatings

    Science.gov (United States)

    Miller, Robert A.; Kuczmarski, Maria A.

    2015-01-01

    Thermodynamic and computational fluid dynamics modeling has been conducted to examine the feasibility of adapting the NASA-Glenn erosion burner rigs for use in studies of corrosion of environmental barrier coatings by the deposition of molten CMAS. The effect of burner temperature, Mach number, particle preheat, duct heating, particle size, and particle phase (crystalline vs. glass) were analyzed. Detailed strategies for achieving complete melting of CMAS particles were developed, thereby greatly improving the probability of future successful experimental outcomes.

  18. Dental erosion among South Brazilian adolescents: A 2.5-year longitudinal study.

    Science.gov (United States)

    Brusius, C D; Alves, L S; Susin, C; Maltz, M

    2018-02-01

    This population-based longitudinal study investigated the incidence, progression and risk factors for dental erosion among South Brazilian adolescents. Eight hundred and one schoolchildren attending 42 public and private schools were clinically examined at 12 years of age; clinical examinations were repeated after 2.5 years (SD=0.3). After tooth cleaning and drying, permanent incisors and first molars were classified using the Basic Erosive Wear Examination (BEWE) scoring criteria. Questionnaires were used to collect data on socio-demographic characteristics, dietary habits, toothbrushing frequency and general health. Poisson regression analysis was used to assess the association between dental erosion incidence and explanatory variables, with adjusted incidence risk ratios (IRR) and 95% CI estimated. Among those who did not have dental erosion at baseline, 49 of 680 schoolchildren (7.1%; 95% CI=5.2-9.1) developed erosive lesions over the follow-up period. Among schoolchildren who had dental erosion at baseline, 31 of 121 (25.4%; 95% CI=17.6-33.3) had new or more severe lesions. Boys were more likely to develop dental erosion than girls (IRR=1.88; 95% CI=1.06-3.32). A moderate incidence of dental erosion was observed among South Brazilian adolescents, with boys being at higher risk. The high progression rate of 25% observed here is very concerning, and it should be taken in consideration when designing preventive strategies for dental erosion. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Compressor Impeller Erosion Resistant Surface Treatment

    National Research Council Canada - National Science Library

    Riley, Michael

    2000-01-01

    ...). Coatings based on tungsten carbide tantalum carbide. titanium carbide all with a cobalt matrix were evaluated for high velocity particle erosion in conventional wear test studies as well as wind tunnel testing...

  20. Wear resistance properties of austempered ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Lerner, Y.S. [Univ. of Northern Iowa, Cedar Falls, IA (United States); Kingsbury, G.R. [Kingsbury (G.R.), Lyndhurst, OH (United States)

    1998-02-01

    A detailed review of wear resistance properties of austempered ductile iron (ADI) was undertaken to examine the potential applications of this material for wear parts, as an alternative to steels, alloyed and white irons, bronzes, and other competitive materials. Two modes of wear were studied: adhesive (frictional) dry sliding and abrasive wear. In the rotating dry sliding tests, wear behavior of the base material (a stationary block) was considered in relationship to countersurface (steel shaft) wear. In this wear mode, the wear rate of ADI was only one-fourth that of pearlitic ductile iron (DI) grade 100-70-03; the wear rates of aluminum bronze and leaded-tin bronze, respectively, were 3.7 and 3.3 times greater than that of ADI. Only quenched DI with a fully martensitic matrix slightly outperformed ADI. No significant difference was observed in the wear of steel shafts running against ADI and quenched DI. The excellent wear performance of ADI and its countersurface, combined with their relatively low friction coefficient, indicate potential for dry sliding wear applications. In the abrasive wear mode, the wear rate of ADI was comparable to that of alloyed hardened AISI 4340 steel, and approximately one-half that of hardened medium-carbon AISI 1050 steel and of white and alloyed cast irons. The excellent wear resistance of ADI may be attributed to the strain-affected transformation of high-carbon austenite to martensite that takes place in the surface layer during the wear tests.

  1. Wearing gloves in the hospital

    Science.gov (United States)

    Infection control - wearing gloves; Patient safety - wearing gloves; Personal protective equipment - wearing gloves; PPE - wearing gloves; Nosocomial infection - wearing gloves; Hospital acquired infection - ...

  2. Wear characterization of abrasive waterjet nozzles and nozzle materials

    Science.gov (United States)

    Nanduri, Madhusarathi

    Parameters that influence nozzle wear in the abrasive water jet (AWJ) environment were identified and classified into nozzle geometric, AWJ system, and nozzle material categories. Regular and accelerated wear test procedures were developed to study nozzle wear under actual and simulated conditions, respectively. Long term tests, using garnet abrasive, were conducted to validate the accelerated test procedure. In addition to exit diameter growth, two new measures of wear, nozzle weight loss and nozzle bore profiles were shown to be invaluable in characterizing and explaining the phenomena of nozzle wear. By conducting nozzle wear tests, the effects of nozzle geometric, and AWJ system parameters on nozzle wear were systematically investigated. An empirical model was developed for nozzle weight loss rate. To understand the response of nozzle materials under varying AWJ system conditions, erosion tests were conducted on samples of typical nozzle materials. The effect of factors such as jet impingement angle, abrasive type, abrasive size, abrasive flow rate, water pressure, traverse speed, and target material was evaluated. Scanning electron microscopy was performed on eroded samples as well as worn nozzles to understand the wear mechanisms. The dominant wear mechanism observed was grain pullout. Erosion models were reviewed and along the lines of classical erosion theories a semi-empirical model, suitable for erosion of nozzle materials under AWJ impact, was developed. The erosion data correlated very well with the developed model. Finally, the cutting efficiency of AWJ nozzles was investigated in conjunction with nozzle wear. The cutting efficiency of a nozzle deteriorates as it wears. There is a direct correlation between nozzle wear and cutting efficiency. The operating conditions that produce the most efficient jets also cause the most wear in the nozzle.

  3. Dental erosion in 12-year-old school children living in Jakarta

    Science.gov (United States)

    Septalita, A.; Bahar, A.; Agustanti, A.; Rahardjo, A.; Maharani, D. A.; Rosalien, R.

    2017-08-01

    This study assesses the dental erosion status of 12-year-old Indonesian children and studies the determinants of dental erosion of these children. The survey was performed in 2016 with ethics approval. A multistage cluster proportional to size random sampling method was adopted to select 12-year-old children in 24 primary schools in Jakarta. The parents were asked to complete a self-administered questionnaire concerning their children’s diet and oral health habits. The children were examined by a single calibrated examiner. Detection of dental erosion followed basic erosive wear examination (BEWE) criteria. A total of 487 children participated in the survey. Most children (88%) had at least some signs of erosion (BEWE > 0), with dentin being involved in 50% of the cases (BEWE = 2). Dental erosion was significantly related to gender, the frequencies of citric tea consumption, parent’s dental knowledge, father’s education, and dental caries (OR = 3.148). The 12-year-old Indonesian school children who lived in Jakarta had signs of erosion, although severe erosion was not found. Screening programs should be provided to identify risk groups so early preventive measures can be taken.

  4. Thin layer activation: measuring wear and corrosion

    International Nuclear Information System (INIS)

    Delvigne, T.; Leyman, D.; Oxorn, K.

    1995-01-01

    The technique known as thin layer activation (TLA) is explained and assessed in this article. Widely used, in for example the automotive industry, TLA allows on-line monitoring of the loss of matter from a critical surface, by wear erosion and corrosion. The technique offers extremely high sensitivity thus leading to reduced test times. On-line wear phenomena can be assessed during operation of a mechanical process, even through thick engine walls. (UK)

  5. Erosion - corrosion mechanisms of stainless steel UNS S31603

    OpenAIRE

    Rajahram, Shiva Suthan

    2010-01-01

    Solid particle erosion-corrosion is the wear caused by the combined action of the mechanical process of solid particle erosion and the electrochemical process of corrosion. This joint action leads to a synergistic interaction that enhances the wear rate of the material, causing severe problems to engineering components exposed to these aggressive conditions. This poses a problem to designers and engineers, as there are currently no robust models available to predict erosion-corrosion rates du...

  6. Thermo-mechanical correlations to erosion performance of short carbon fibre reinforced vinyl ester resin composites

    International Nuclear Information System (INIS)

    Kumar, Sandeep; Satapathy, Bhabani K.; Patnaik, Amar

    2011-01-01

    Research highlights: → Composite with 30 wt.% of short carbon fibres exhibit highest energy dissipation. → Optimum erosion resistance conditions have been found. → A direct correlation emerged between erosive wear rate and loss-modulus inverse. → Mechanistic equivalence between erosion and dynamic loading modes is established. -- Abstract: Thermo-mechanical properties and erosion performance of short carbon fibre reinforced vinyl ester resin based isotropic polymer composites with four different fibre weight fractions have been investigated. The storage, loss and damping characteristics were analysed to assess the energy absorption/viscous recoverable energy dissipation and reinforcement efficiency of the composites as a function of fibre content in the temperature range of 0-140 o C. The composite with 30 wt.% of short carbon fibres has been observed to exhibit superior thermo-mechanical response with highest energy dissipation/damping ability accompanied with a constant storage modulus without any substantial decay till 60 o C. The erosion rates (Er) of these composites are evaluated at different impingement angles (30-90 o ), fibre loadings (20-50 wt.%), impact velocities (43-76 m/s), stand-off distances (55-85 mm) and erodent sizes (250-600 μm) following the erosion test schedule in an air jet type test rig. An optimal parameter combination is determined and subsequently validated for erosion rate minimization following Taguchi method and by conducting confirmation experiments. A correlation between the loss-modulus inverse and the erosion rate has been observed which conceptually establishes a possible mechanistic equivalence between erosion and dynamic mechanical loading modes. The morphologies of eroded surface are examined by the scanning electron microscopy to investigate the nature of wear-craters, material damage mode and other qualitative attributes responsible for promoting erosion.

  7. Prediction of wear rates in comminution equipment

    DEFF Research Database (Denmark)

    Jensen, Lucas Roald Dörig; Fundal, Erling; Møller, Per

    2010-01-01

    -resistant high chromium white cast iron (21988/JN/HBW555XCr21), a heat-treated wear resistant steel (Hardox 400) and a plain carbon construction steel (S235). Quartz, which accounts for the largest wear loss in the cement industry, was chosen as abrasive. Other process parameters such as velocity (1–7 m....../s) and pressure (70–1400 kPa) were chosen to closely imitate real industrial processes. The authors are aware that a number of wear mechanisms such as erosion, fatigue and abrasion may occur simultaneously in comminution equipment. Nonetheless, this paper aims at discussing abrasion only due to its large...

  8. Cavitation wear of pump impellers

    Directory of Open Access Journals (Sweden)

    Mirosław Szala

    2016-12-01

    Full Text Available Cavitation is a common phenomenon in pump systems, negatively influencing their operating parameters and components such as impellers and, thus, causing considerable financial losses. This paper explains the problem of cavitation and cavitation erosion. The causes of cavitation in pump systems are analyzed. A selection of centrifugal pump impellers damaged by cavitation erosion are presented and examined. The authors also discuss ways of preventing cavitation and cavitation erosion in pump systems. Finally, relevant conclusions are drawn.

  9. Prevalence of dental erosion among 18-year-old adolescents in the borderland districts of Lviv (Ukraine) and Lublin (Poland).

    Science.gov (United States)

    Bachanek, Teresa; Hendzel, Barbara; Wolańska, Ewa; Szybinsky, Volodymir; Ogonovsky, Roman; Hrynovets, Volodymir; Samborski, Dariusz; Nakonieczna-Rudnicka, Marta; Chałas, Renata

    2018-03-14

    Recent epidemiological studies have shown an association between dental erosion occurrence and changes in lifestyle and dietary habits in both developed and developing countries, and now affects different regions of the world. Furthermore, in current literature, studies have shown that the prevalence of erosive tooth wear has increased particularly among the younger population. The aim of the study was to assess the prevalence and severity of erosive tooth wear among 18-year-old adolescents in the districts of Lviv (Ukraine) and Lublin (Poland). College students (254 subjects) aged 18, living in the Lviv and Lublin districts were examined. Erosive lesions presented in the teeth were assessed on the basis of the BEWE (Basic Erosive Wear Examination) index. Among the 137 patients living in the Lublin district, 70 were females and 67 were males, while in the Lviv district, 60 women and 57 men were examined. In both districts, the following numbers of rural patients were examined: 66 in Lublin district and 56 in Lviv district; for urban inhabitants, the numbers were 71 in Lublin and 61 in Lviv. Analysing the BEWE values, it was noted that higher BEWE values, and resulting from them significant differences were observed in both male and female groups living in Lublin, compared with Lviv inhabitants. Based on clinical examination and statistical analysis, the occurrence of lesions of an erosive character in at least one sextant were observed in 59.85% of patients from Lublin district, and in 42.74% of patients from Lviv district. On the basis of the conducted study in the Polish and Ukrainian groups of 18-year-old adolescents living on the borderland, it can be stated that dental erosion is a problem noticeable in both groups of cohorts, but with higher prevalence in the Lublin district.

  10. Effect of dental erosion on oral health among employees of battery-manufacturing units in Baddi, Himachal Pradesh, India.

    Science.gov (United States)

    Bansal, Mohit; Singh, Sunint; Bector, Aditi; Dogra, Mrigank

    2018-01-01

    The objective of the study was to obtain data on prevalence and severity of dental erosion among acid industry workers in Baddi (Himachal Pradesh). A cross-sectional study was conducted among 800 battery industry workers. The demographic details were recorded on a prestructured pro forma. Type III examination was done. Dental erosion was recorded based on the index given by Bardsley (simplified scoring criteria for tooth wear index). Appropriate statistical tests were used to interpret the data. The prevalence of dental erosion was found to be 48.6%. Prevalence increased with the duration of employment. Dental erosion was most commonly found in the labial surfaces of maxillary anterior teeth. Erosion is a condition which is multifactorial and becomes more aggravating in the presence of acidic environment. Therefore, the workers working in such conditions should be more careful, and mandatory policies should also be followed by such industries to maintain the overall health of the workers.

  11. The influence of frequently consumed beverages and snacks on dental erosion among preschool children in Saudi Arabia.

    Science.gov (United States)

    Al-Dlaigan, Yousef H; Al-Meedania, Laila A; Anil, Sukumaran

    2017-12-11

    To determine the prevalence of dental erosion and its association to commonly used beverages and snacks among 3 to 5 year old preschool children in Riyadh, Saudi Arabia. Three hundred eighty-eight preschool children between 3 and 5 years old were selected from 10 different schools using a cluster random sample selection; there were 184 (47%) boys and 204 (53%) girls. The surfaces of each tooth were examined for erosion, and the level of tooth wear was recorded. Data on the frequently used beverages and snacks were obtained by questionnaires completed by the parents of the preschool children. Among the 388 children examined, 47% exhibited low erosion, 10% exhibited moderate erosion and 4% exhibited severe erosion. There was no statistically significant difference between boys and girls in terms of the prevalence of erosion. Sixty percent of the children regularly consumed juice drinks. Among daily consumers, 84% of children showed erosion prevalence with strongly significant association (p erosion (p erosion and the frequency of citrus and carbonated juice consumed by the preschool children in Saudi Arabia.

  12. Slurry erosion and abrasion of metal-ceramic coatings

    International Nuclear Information System (INIS)

    Sagues, A.A.; Spencer, D.K.; Sethi, V.K.; Sargent, G.A.

    1987-01-01

    Four coatings, including tungsten carbide wear-resistant and cobalt-base corrosion-resistant materials, were tested for abrasion and erosion performance in silica sand and in Alundum slurries. A 1018 carbon steel sample was also tested for comparison. The abrasion tests were conducted with a wet sand rubber wheel device, whereas a slurry jet impingement apparatus was used in the erosion tests. The results revealed that the abrasive wear performance improves dramatically as the coating hardness increases. By contrast, the erosion performance was not clearly related to the hardness of the materials tested. The wear mechanisms and the suitability of the test methods to evaluate coatings are discussed

  13. Fluoridation and tooth wear in Irish adults.

    LENUS (Irish Health Repository)

    Burke, F M

    2010-10-01

    The aim of this study was to determine the prevalence of tooth wear in adults in Ireland and its relationship with water fluoridation. The National Survey of Adult Oral Health was conducted in 2000\\/2001. Tooth wear was determined using a partial mouth examination assessing the upper and lower anterior teeth. A total of 2456 subjects were examined. In this survey, increasing levels and severity of tooth wear were associated with ageing. Men were more affected by tooth wear and were more likely to be affected by severe tooth wear than women. It was found that age, and gender were significant predictors of tooth wear (P < 0.01). Overall, there was no significant relationship between fluoridation and tooth wear in this study.

  14. Meta-analysis of the prevalence of tooth wear in primary dentition.

    Science.gov (United States)

    Corica, A; Caprioglio, A

    2014-12-01

    To conduct a meta-analysis of all the studies published in literature over the past three decades on the prevalence of dental erosion in preschool children. The Pubmed data base revealed only one systematic review on the prevalence of tooth wear in children up to 5 years old. The search included works published from January 1982 to September 2012, using the following combinations of keywords: 1) "dental erosion" AND "children"; 2) "dental erosion in primary dentition"; 3) "dental" AND "attrition" AND "prevalence". The inclusion criteria for papers on tooth wear were the deciduous dentition observed only on the palatal and buccal sides with the distinction of erosion, attrition and abrasion. We took into consideration only randomized control trials. We excluded articles not written in English, case reports, historical and forensic studies, in vitro and in vivo studies. In case of doubt and/or when an abstract was not available, the full text copy of the article was examined. The first search on Pubmed revealed 29 articles, the same found in the study of Kreulen [2010], however we selected only multicentric studies focused on children of age below 5 years old, in which only the primary dentition (D) and only anterior teeth (incisors) were considered. Both forest plot and scatter plot showed the prevalence of dental erosion in primary dentition, and that older children had a more severe dental erosion. Dental erosion should be considered a paediatric dentistry pathological entity as well as dental caries, and it can be related to more severe systemic diseases such as Gastroesophageal reflux disease. In addition, taking care of these little patients is important because they might suffer persentiveness, and also pulpal pathology caused by the typical structure of deciduous teeth, where the pulp cavity is wide and close to the dentine and the enamel.

  15. Dental Erosion and Dentinal Sensitivity amongst Professional Wine Tasters in South East Queensland, Australia

    Directory of Open Access Journals (Sweden)

    Roy George

    2014-01-01

    Full Text Available Background/Aims. Professional wine tasters face a hidden occupational hazard due to the high acid content in wine. This study evaluates the self-perceived dentinal sensitivity and erosive effects of wine on the professional wine tasters of the Granite Belt and the Scenic Rim regions of South East Queensland, Australia. Methods. Seventy wineries were contacted and participants were surveyed about their professional wine tasting experience and oral health. Participants were also required to rate their tooth sensitivity prior to being examined for erosion using a modified Smith & Knight tooth wear index. The data were analysed using Mann Whitney U test and Spearman’s correlation test. Results. The results showed that most participants (25 males, 22–66 yrs, brushed twice a day; however, the majority did not floss daily and had limited knowledge of the erosive effect of wine. There was a direct correlation between years of wine tasting, age of participants, and the erosion index. Correlation was not observed between the participant’s sensitivity index and erosion index. Conclusion. The lack of significant experience of dentinal hypersensitivity amongst professional wine tasters should not prevent oral health practitioners from providing necessary counselling and undertaking preventive measures, as tooth wear can have serious long-term effect on oral health of an individual.

  16. Erosive gastritis

    International Nuclear Information System (INIS)

    Mohammed, S.H.; Conrad, C.; Kjoergaad, J.

    1982-01-01

    Erosive gastritis is a well-defined radiologic and endoscopic entity. It is one of the common causes of upper gastrointestinal bleeding, yet it is seldom diagnosed and often confused with a number of other diseases. This communication re-emphasizes the characteristic endoscopic and radiologic features of erosive gastritis and its differential diagnosis. Two representative cases are reported. (orig.)

  17. The role of fluoride in erosion therapy.

    Science.gov (United States)

    Huysmans, Marie-Charlotte; Young, Alix; Ganss, Carolina

    2014-01-01

    The role of fluoride in erosion therapy has long been questioned. However, recent research has yielded positive results. In this chapter, an overview of the literature is provided regarding the application of fluorides in the prevention and treatment of erosion and erosive wear. The results are presented and discussed for different fluoride sources such as monovalent and polyvalent fluorides, and for different vehicles such as toothpastes, solutions and rinses, as well as varnishes and gels. It is concluded that fluoride applications are very likely to be of use in the preventive treatment of erosive wear. Most promising are high-concentration, acidic formulations and the polyvalent fluoride sources, with the best evidence available for stannous fluoride. However, the evidence base for clinical effectiveness is still small. © 2014 S. Karger AG, Basel.

  18. DENTAL EROSION IN PRIMARY DENTITION- A REVIEW

    Directory of Open Access Journals (Sweden)

    Rafi Shaik

    2017-06-01

    Full Text Available BACKGROUND The pattern of oral diseases has been influenced by ever changing human lifestyle. Tooth wear especially dental erosion has drawn increasing attention as risk factor for tooth damage or loss in recent years. It is a common condition in primary dentition compared to permanent dentition due to thinner and less mineralised enamel. However, it is more worrying, when this condition is being found in an alarming proportion among children. The presence of dental erosion in children is likely to be associated with a number of general health and dietary factors, but it is also aggravated by the relatively more rapid progression of erosion in the deciduous teeth. An understanding of the aetiologies and risk factors for erosion is important for early recognition of dental erosion to prevent serious irreversible damage to the dentition. This paper discusses the erosion in children with regard to its epidemiology, prevalence, clinical features, measurement and prevention.

  19. Ceramic wear maps: Zirconia

    International Nuclear Information System (INIS)

    Lee, S.W.; Hsu, S.M.; Shen, M.C.

    1993-01-01

    The wear characteristics of an yttria-stabilized zirconia (Y-TZP) are represented by a set of three-dimensional wear maps under dry and lubricated conditions. Water, paraffin oil, and a formulated oil were used as lubricants. Different wear regions were identified as a function of load, speed, and lubrication environment. Sudden increases in wear, identified as ear transitions, were found at certain loads and speeds. The onset of wear transitions was moderated by the presence of a lubricant. Below the wear transitions, the wear was mild and the wear mechanism was predominantly plastic deformation and microfracture. Above the wear transitions, the wear was severe, dominated by brittle fracture and third-body abrasion. Different fluids had different effects on wear. Water had a deleterious effect on wear for this material. The presence of oil lubricants effectively reduced friction and moderated wear. Under high load and high speed, additional stress induced by a thermal gradient within a small area contributed significantly to wear. A critical velocity model was found to describe the locations of the wear transition zones successfully

  20. Severe tooth wear in Prader-Willi syndrome. A case–control study

    Directory of Open Access Journals (Sweden)

    Saeves Ronnaug

    2012-05-01

    Full Text Available Abstract Background Prader-Willi syndrome (PWS is a rare complex multsystemic genetic disorder characterized by severe neonatal hypotonia, endocrine disturbances, hyperphagia and obesity, mild mental retardation, learning disabilities, facial dysmorphology and oral abnormalities. The purpose of the present study was to explore the prevalence of tooth wear and possible risk factors in individuals with Prader-Willi syndrome. Methods Forty-nine individuals (6-40 years with PWS and an age- and sex-matched control group were included. Tooth wear was evaluated from dental casts and intraoral photographs and rated by four examiners using the Visual Erosion Dental Examination (VEDE scoring system and the individual tooth wear index IA. In accordance with the VEDE scoring system, tooth wear was also evaluated clinically. Whole saliva was collected. Results Mean VEDE score was 1.70 ± 1.44 in the PWS group and 0.46 ± 0.36 in the control group (p A was 7.50 (2.60-30.70 in the PWS group and 2.60 (0.90-4.70 among controls (p A; r = 0.82, p A; r = 0.43, p = 0.002. Tooth grinding was also associated with tooth wear in the PWS group, as indicated by the mean VEDE 2.67 ± 1.62 in grinders and 1.14 ± 0.97 in non-grinders (p = 0.001 and median IA values 25.70 (5.48-68.55 in grinders and 5.70 (1.60-9.10 in non-grinders (p = 0.003. Multivariate linear regression analysis was performed with tooth wear as the dependent variable and PWS (yes/no, age, tooth grinding and saliva secretion as independent variables. PWS (yes/no, age and tooth grinding retained a significant association with tooth wear, VEDE (p A (p  Conclusions Our study provides evidence that tooth wear, in terms of both erosion and attrition, is a severe problem in Prader-Willi syndrome. There is therefore considerable need for prosthodontic rehabilitation in young adults with PWS.

  1. Analysis of Wear Particles Formed in Boundary-Lubricated Sliding Contacts

    NARCIS (Netherlands)

    Akchurin, Aydar; Bosman, Rob; Lugt, Pieter Martin; van Drogen, Mark

    2016-01-01

    The wear process in a sliding contact results in generation of wear debris, which affects the system life. The impact depends on the wear particle properties, such as size, shape and number. In this paper, the wear particles formed during a cylinder-on-disk wear test were examined. PAO additive-free

  2. Cavitation erosion resistance of 13/4 and 21-4-N steels

    Indian Academy of Sciences (India)

    ASTM G32-06 2007 Standard test method for cavitation erosion using vibratory apparatus, West. Conshohocken, PA. Liu W, Zheng Y G, Liu C S, Yao Z M and Ke W 2003 Wear 254: 713. Okada T, Iwai Y and Yamamoto A 1983 Wear 84: 297. Garzon C M, Thomas H, Santos J F and Tschiptschin A P 2005 Wear 259: 145.

  3. Dental erosion due to lime consumption; review of literature and ...

    African Journals Online (AJOL)

    Background: Dental health is increasingly threatened by dental erosion introduced by today's lifestyle. Extrinsic factor is the most implicated. Few literatures mentioned lime-incited dental erosion. Case Description: A 49 year old woman was referred to our clinic with tooth wear and sensitivity. She was in good health but on ...

  4. Dynamic SEM wear studies of tungsten carbide cermets. [friction and wear experiments

    Science.gov (United States)

    Brainard, W. A.; Buckley, D. H.

    1975-01-01

    Dynamic friction and wear experiments were conducted in a scanning electron microscope. The wear behavior of pure tungsten carbide and composite with 6 and 15 weight percent cobalt binder was examined, and etching of the binder was done to selectively determine the role of the binder in the wear process. Dynamic experiments were conducted as the tungsten carbide (WC) and bonded WC cermet surfaces were transversed by a 50 micron radiused diamond stylus. These studies show that the predominant wear process in WC is fracture initiated by plastic deformation, and the wear of the etched cermets is similar to pure WC. The presence of the cobalt binder reduces both friction and wear. The cementing action of the cobalt reduces granular separation, and promotes a dense polished layer because of its low shear strength film-forming properties. The wear debris generated from unetched surface is approximately the same composition as the bulk.

  5. Severe tooth wear in Prader-Willi syndrome. A case-control study.

    Science.gov (United States)

    Saeves, Ronnaug; Espelid, Ivar; Storhaug, Kari; Sandvik, Leiv; Nordgarden, Hilde

    2012-05-28

    Prader-Willi syndrome (PWS) is a rare complex multsystemic genetic disorder characterized by severe neonatal hypotonia, endocrine disturbances, hyperphagia and obesity, mild mental retardation, learning disabilities, facial dysmorphology and oral abnormalities. The purpose of the present study was to explore the prevalence of tooth wear and possible risk factors in individuals with Prader-Willi syndrome. Forty-nine individuals (6-40 years) with PWS and an age- and sex-matched control group were included. Tooth wear was evaluated from dental casts and intraoral photographs and rated by four examiners using the Visual Erosion Dental Examination (VEDE) scoring system and the individual tooth wear index IA. In accordance with the VEDE scoring system, tooth wear was also evaluated clinically. Whole saliva was collected. Mean VEDE score was 1.70 ± 1.44 in the PWS group and 0.46 ± 0.36 in the control group (p Prader-Willi syndrome. There is therefore considerable need for prosthodontic rehabilitation in young adults with PWS.

  6. Comparative wear mapping techniques

    DEFF Research Database (Denmark)

    Alcock, J.; Sørensen, Ole Toft; Jensen, S.

    1996-01-01

    Pin-on-disc tests of tungsten carbide pins against silicon carbide discs were performed and wear rate, mechanism and friction maps constructed. Correlations were observed between the wear mode and the friction of the pin-disc interface, and between the qualitative incidence of disruptive wear mec...

  7. Association between Severity of Tooth Wear and Dentinal Hypersensitivity

    Directory of Open Access Journals (Sweden)

    Ashok Ayer

    2016-11-01

    Full Text Available Background & Objectives: Tooth wear (attrition, abrasion, erosion, and abfraction is perceived globally as ever increasing problem. Several outcome of the tooth wear are hypersensitivity, esthetic problems, functional impairment, annoyance to the patient, and fracture of the tooth. Among these, the measurable and more commonly reported outcome is hypersensitivity to stimuli. Although dentin hypersensitivity is a common clinical condition and is generally reported by the patient after experiencing a sharp, short pain caused by one of the several different external stimuli, it is often inadequately understood. None of the scientific literature available till date attempted to establish the relationship between tooth wear and dentin hypersensitivity which could be a key factor in monitoring those patients.  The aim of the study was to estimate the association between severity of teeth wear and sensitivity in the patients with reported dentinal hypersensitivity.Materials & Methods: Fifty patients with dentin hypersensitivity were investigated for tooth wear. Tooth wear measured using exact tooth wear index and level of sensitivity to stimuli was recorded using a numerical rating scale. Results: Enamel wear at cervical region of teeth showed a positive correlation (p=.010, similarly, dentin wear at cervical region of teeth showed positive correlation and significant association (p<.001 with dentinal hypersensitivity.Conclusion: The observation supports a significant association between severities of tooth surface wear and dentinal hypersensitivity.

  8. Numerical Analysis of Flow Erosion on Sand Discharge Pipe in Nitrogen Drilling

    Directory of Open Access Journals (Sweden)

    Hongjun Zhu

    2013-01-01

    Full Text Available In nitrogen drilling, entrained sand particles in the gas flow may cause erosive wear on metal surfaces and have a significant effect on the operational life of discharge pipelines, especially for elbows. In this paper, computational fluid dynamics (CFD simulations based code FLUENT is carried out to investigate the flow erosion on a sand discharge pipe in conjunction with an erosion model. The motion of the continuum phase is captured based on solving the three-dimensional Reynolds-averaged Navier-Stokes (RANS equations, while the kinematics and trajectory of the sand particles are evaluated by the discrete phase model (DPM. The flow field has been examined in terms of pressure, velocity, and erosion rate profiles along the flow path in the bend of the simulated discharge pipe. Effects of flow parameters such as inlet velocity, sandy volume fraction, and particle diameter and structure parameters such as pipe diameter and bend curvature are analyzed based on a series of numerical simulations. The results show that small pipe diameter or small bend curvature leads to serious erosion, while slow flow, little sandy volume fraction, and small particle diameter can weaken erosion. The results obtained from the present work provide useful guidance to practical operation and discharge pipe design.

  9. Wear resistance of cast iron

    OpenAIRE

    S. Pietrowski; G. Gumienny

    2008-01-01

    In this paper investigations of abrasive and adhesive wear resistance of different cast iron grades have been presented. Examinations showed, that the most advantageous pair of materials is the cast iron – the hardened steel with low-tempered martensite. It was found, that martensitic nodular cast iron with carbides is the most resistant material.

  10. Erosion resistance comparison of alternative surface treatments

    Science.gov (United States)

    Česánek, Z.; Schubert, J.; Houdková, Š.

    2017-05-01

    Erosion is a process characterized by the particle separation and the damage of component functional surfaces. Thermal spraying technology HP/HVOF (High Pressure / High Velocity Oxygen Fuel) is commonly used for protection of component surfaces against erosive wear. Alloy as well as cermet based coatings meet the requirements for high erosion resistance. Wear resistance is in many cases the determining property of required component functioning. The application suitability of coating materials is particularly influenced by different hardness. This paper therefore presents an erosion resistance comparison of alloy and cermet based coatings. The coatings were applied on steel substrates and were subjected to the erosive test using the device for evaluation of material erosion resistance working on the principle of centrifugal erodent flow. Abrasive sand Al2O3 with grain size 212-250 μm was selected as an erosive material. For this purpose, the specimens were prepared by thermal spraying technology HP/HVOF using commercially available powders Stellite 6, NiCrBSi, Cr3C2-25%NiCr, Cr3C2-25%CoNiCrAlY, Hastelloy C-276 and experimental coating TiMoCN-29% Ni. Erosion resistance of evaluated coatings was compared with erosive resistance of 1.4923 high alloyed steel without nitridation and in nitrided state and further with surface treatment using technology PVD. According to the evaluation, the resulting erosive resistance depends not only on the selected erodent and surface protection, but also on the erodent impact angle.

  11. Abrasive wear of intermetallics

    International Nuclear Information System (INIS)

    Hawk, J.A.; Alman, D.E.; Wilson, R.D.

    1995-01-01

    The US Bureau of Mines is investigating the wear behavior of a variety of advanced materials. Among the many materials under evaluation are intermetallic alloys based on the compounds: Fe 3 Al, Ti 3 Al, TiAl, Al 3 Ti, NiAl and MoSi 2 . The high hardness, high modulus, low density, and superior environmental stability of these compounds make them attractive for wear materials. This paper reports on the abrasive wear of alloys and composites based on the above compounds. The abrasive wear behavior of these alloys and composites are compared to other engineering materials used in wear applications

  12. Wear monitoring of single point cutting tool using acoustic emission ...

    Indian Academy of Sciences (India)

    This paper examines the flank and crater wear characteristics of coated carbide tool inserts during dry turning of steel workpieces. A brief review of tool wear mechanisms is presented together with new evidence showing that wear of the TiC layer on both flank and rake faces is dominated by discrete plastic deformation, ...

  13. RESISTENCIA AL DESGASTE EROSIVO-CORROSIVO DE ACEROS AUSTENÍTICOS FERMANAL RESISTÊNCIA AO DESGASTE EROSIVO-CORROSIVO DE AÇOS AUSTENÍTICOS FERMANAL EROSIVE-CORROSIVE WEAR RESISTANCE OF FERMANAL AUSTENITIC STEELS

    Directory of Open Access Journals (Sweden)

    Willian Aperador

    2012-12-01

    the range (4.9~11.0 wt% Al - (17.49~34.3 wt% Mn - (0, 43~1.25 wt% C, which were melted in an induction furnace from high purity materials. The alloys were evaluated with respect to corrosion, wet erosion and corrosion-erosion at an impact angle of 90°. For the evaluation of corrosion a solution composed of 0.5 M NaCl and silica particles with size between 210 to 300 microns was used in order to analyze the effect of aluminum and manganese content in the resistance to erosion and corrosion-erosion of these alloys. To characterize the corrosion, response technique was used by potentiodynamic polarization curves and using the same technique as Tafel extrapolation, the microstructural characterization by scanning electron microscopy (SEM, and the composition of corrosion products were analyzed using diffraction of X-rays (XRD.

  14. Dental Wear: A Scanning Electron Microscope Study

    Directory of Open Access Journals (Sweden)

    Luca Levrini

    2014-01-01

    Full Text Available Dental wear can be differentiated into different types on the basis of morphological and etiological factors. The present research was carried out on twelve extracted human teeth with dental wear (three teeth showing each type of wear: erosion, attrition, abrasion, and abfraction studied by scanning electron microscopy (SEM. The study aimed, through analysis of the macro- and micromorphological features of the lesions (considering the enamel, dentin, enamel prisms, dentinal tubules, and pulp, to clarify the different clinical and diagnostic presentations of dental wear and their possible significance. Our results, which confirm current knowledge, provide a complete overview of the distinctive morphology of each lesion type. It is important to identify the type of dental wear lesion in order to recognize the contributing etiological factors and, consequently, identify other more complex, nondental disorders (such as gastroesophageal reflux, eating disorders. It is clear that each type of lesion has a specific morphology and mechanism, and further clinical studies are needed to clarify the etiological processes, particularly those underlying the onset of abfraction.

  15. Erhversbetinget erosion?

    DEFF Research Database (Denmark)

    Dige, Irene; Gjørup, Hans; Nyvad, Bente

    2012-01-01

    Baggrund – I forbindelse med dental erosion er en grundig udredning af patienten vigtig, således at årsagen til erosionernes opståen findes, og der kan iværksættes adækvat forebyggende indsats. En sådan udredning er ikke mindst vigtig, når arbejdsmiljøet mistænkes. Patienttilfælde – En 30-årig...... arbejdsskade, men ikke anerkendt, da erosioner ikke er optaget på Arbejdsskadestyrelsens liste over erhvervssygdomme. En systematisk registrering af lignende tilfælde kunne imidlertid på sigt ændre retspraksis for fremtidige patienter med arbejdsbetinget erosion....

  16. The Wearing Out of Genre Materials

    Science.gov (United States)

    Russ, Joanna

    1971-01-01

    Scenes and plots wear out in three distinct stages: Innocence, Plausibility, and Decadence. Examines westerns, spy stories, nurse novels, detective stories, science fiction, pornography, avant-garde fiction, etc. (Author/RB)

  17. Polymer wear evaluation

    DEFF Research Database (Denmark)

    Lagerbon, Mikkel; Sivebæk, Ion Marius

    2012-01-01

    Polymer wear plays an increasing role in manufacturing of machine parts for e.g. medical devices. Some of these have an expected lifetime of five to eight years during which very little wear of the components is acceptable. Too much wear compromises the dosage accuracy of the device and thereby...... the safety of the patients. Prediction of the wear of polymers is complicated by the low thermal conductivity of this kind of material. It implies that any acceleration of testing conditions by increased contact pressure and/or sliding velocity will make the polymer fail due to exaggerated heat buildup....... This is not the kind of wear observed in medical devices. In the present work a method was developed capable of evaluating the wear progression in polymer-polymer contacts. The configuration of the setup is injection moulded specimens consisting of an upper part having a toroid shape and a lower flat part. The sliding...

  18. Thin film, channelized drainage, or sheetfloods beneath a portion of the Laurentide Ice Sheet: an examination of glacial erosion forms, northern New York State, USA

    Science.gov (United States)

    Pair, Donald L.

    1997-07-01

    Morphologic analyses of characteristic bedrock erosion forms found in northern New York State, USA were used to reconstruct the subglacial conditions under which they may have been produced. Observations from sites on Wellesley Island, N.Y, at Point Salubrious, N.Y, and at an open pit mine near Balmat, N.Y, were combined with regional mapping of a diverse suite of glacial erosion forms in order to establish the areal extent and significance of subglacial drainage in northern New York. Results of these site-specific and regional studies are the basis for discussion of the probable role of subglacial meltwater in the region. Bedrock erosion forms preserved at various locations in northern New York are interpreted as products of flow separation of localized subglacial meltwater during ice/bed decoupling. The regional distribution of these forms indicates that they are largely restricted to pre-existing subglacially-modified bedrock valleys that served as subglacial tunnel channels. Regionally extensive, deep, subglacial meltwater flow, characterized as sheetfloods, is not required to account for the erosional features described from specific sites in northern New York State.

  19. Friction and wear of stainless steel, titanium and aluminium with various surface treatments, ion implantation and overlay hard coatings

    International Nuclear Information System (INIS)

    Bunshah, R.F.

    1979-01-01

    This paper deals with the evaluation of the wear properties of 304 stainless steel, commercial grade titanium and commercial grade aluminium without and with different surface treatments, i.e., ion implantation of boron and nitrogen, and overlay coating of superhard materials, titanium carbide and nitride by the Biased Activated Reactive Evaporation (BARE) process. Wear properties were evaluated in adhesive, erosive and abrasive modes of wear. In the case of adhesive wear, ion implantation resulted in an improved wear behaviour in lubricated conditions but had no beneficial effect in dry wear conditions. Overlay coatings on the other hand resulted in improved wear behaviour for both the dry and lubricating conditions. In the case of erosive wear with SiC particles at high velocities, overlay coatings showed higher erosion rates (typical of brittle materials in normal impingement) whereas ion implanted materials behaved similarly as untreated materials; i.e., a lower wear rate than the specimens with overlay coatings. In the case of abrasive wear, it was again observed that the wear rates of overlay coatings is far lower than the wear rates of untreated or ion implanted materials. (author)

  20. Tooth Wear Inclination in Great Ape Molars.

    Science.gov (United States)

    Knight-Sadler, Jordan; Fiorenza, Luca

    2017-01-01

    Primate dietary diversity is reflected in their dental morphology, with differences in size and shape of teeth. In particular, the tooth wear angle can provide insight into a species' ability to break down certain foods. To examine dietary and masticatory information, digitized polygon models of dental casts provide a basis for quantitative analysis of wear associated with tooth attrition. In this study, we analyze and compare the wear patterns of Pongo pygmaeus, Gorilla gorillagorilla and Pan troglodytes schweinfurthii lower molars, focusing on the degree of inclination of specific wear facets. The variation in wear angles appears to be indicative of jaw movements and the specific stresses imposed on food during mastication, reflecting thus the ecology of these species. Orangutans exhibit flatter wear angles, more typical of a diet consisting of hard and brittle foods, while gorillas show a wear pattern with a high degree of inclination, reflecting thus their more leafy diet. Chimpanzees, on the other hand, show intermediate inclinations, a pattern that could be related to their highly variable diet. This method is demonstrated to be a powerful tool for better understanding the relationship between food, mastication and tooth wear processes in living primates, and can be potentially used to reconstruct the diet of fossil species. © 2017 S. Karger AG, Basel.

  1. Vibrational characteristics and wear of fuel rods

    International Nuclear Information System (INIS)

    Schmugar, K.L.

    1977-01-01

    Fuel rod wear, due to vibration, is a continuing concern in the design of liquid-cooled reactors. In my report, the methodology and models that are used to predict fuel rod vibrational response and vibratory wear, in a light water reactor environment, are discussed. This methodology is being followed at present in the design of Westinghouse Nuclear Fuel. Fuel rod vibrations are expressed as the normal bending modes, and sources of rod vibration are examined with special emphasis on flow-induced mechanisms in the stable flow region. In a typical Westinghouse PWR fuel assembly design, each fuel rod is supported at multiple locations along the rod axis by a square-shaped 'grid cell'. For a fuel rod /grid support system, the development of small oscillatory motions, due to fluid flow at the rod/grid interface, results in material wear. A theoretical wear mode is developed using the Archard Theory of Adhesive Wear as the basis. Without question certainty, fretting wear becomes a serious problem if it progresses to the stage where the fuel cladding is penetrated and fuel is exposed to the coolant. Westinghouse fuel is designed to minimize fretting wear by limiting the relative motion between the fuel rod and its supports. The wear producing motion between the fuel rod and its supports occurs when the vibration amplitude exceeds the slippage threshold amplitude

  2. Protective effect of green tea on dentin erosion and abrasion

    Directory of Open Access Journals (Sweden)

    Melissa Thiemi Kato

    2009-12-01

    Full Text Available OBJECTIVE: This in situ study evaluated the protective effect of green tea on dentin erosion (ERO and erosion-abrasion (ABR. MATERIAL AND METHODS: Ten volunteers wore intraoral palatal appliances with bovine dentin specimens subjected to ERO or ERO + toothbrushing abrasion performed immediately (ERO+I-ABR or 30 min after erosion (ERO+30-min-ABR. During 2 experimental 5-day crossover phases, the volunteers rinsed with green tea or water (control, 1 min between each erosive (5 min, cola drink and abrasive challenge (30 s, toothbrushing, 4x/day. Dentin wear was measured by profilometry. RESULTS: The green tea reduced the dentin wear significantly for all conditions compared to control. ERO+I-ABR led to significantly higher wear than ERO, but it was not significantly different from ERO+30-min-ABR. ERO+30-min-ABR provoked significant higher wear than ERO, only for the placebo treatment. CONCLUSIONS: From the results of the present study, it may be concluded that green tea reduces the dentin wear under erosive/abrasive conditions.

  3. Solid particle erosion and viscoelastic properties of thermoplastic polyurethanes

    Directory of Open Access Journals (Sweden)

    G. Arena

    2015-03-01

    Full Text Available The wear resistance of several thermoplastic polyurethanes (TPUs having different chemical nature and micronscale arrangement of the hard and soft segments has been investigated by means of erosion and abrasion tests. The goal was correlating the erosion performances of the materials to their macroscopic mechanical properties. Unlike conventional tests, such as hardness and tensile measurements, viscoelastic analysis proved to be a valuable tool to study the erosion resistance of TPUs. In particular, a strict correlation was found between the erosion rate and the high-frequency (~107 Hz loss modulus. The latter reflects the actual ability of TPU to dissipate the impact energy of the erodent particles.

  4. Prevalence and factors associated with dental erosion in individuals aged 12–30 years in a northeastern Brazilian city

    Directory of Open Access Journals (Sweden)

    Luciano LC

    2017-10-01

    Full Text Available Luanda Cristina O Luciano,1 Meire Coelho Ferreira,2 Marco Aurelio Paschoal2 1Dentistry Program, Facimp Devry, Imperatriz, 2Post Graduate Program in Dentistry, CEUMA University, São Luís, Brazil Background/Purpose: Dental erosion in young individuals has increased significantly in recent years, due to changes in lifestyle. Thus, the present study investigated the prevalence and factors associated with dental erosion in individuals aged 12–30 years in the city of Imperatriz of Maranhão, Brazil.Materials and methods: A cross-sectional study was conducted on 335 individuals who answered a questionnaire consisting of variables related to dental erosion. Afterwards, the individuals were subjected to clinical examinations and the basic erosive wear examination index was used to classify their teeth according to the presence and severity of dental erosion.Results: Descriptive statistics, the chi-square test, Poisson univariate and multivariate regression were performed at 5% level of significance. The sample was characterized by 204 females (60.9%, the majority of whom were from 12 to 19 years of age (78.5%, among whom 28.7% ­presented dental erosion. Their monthly family income was from 1 to 3 minimum wages (56.4%. The variables that were significantly associated with the outcome were family income, chewing gum, and consumption of soft-drinks/juices before going to sleep (p=0.03, p=0.001, and p=0.04, respectively. Individuals who chewed chewing gum were 2.27 times (95% CI =1.43–3.60 more likely to present dental erosion than those who did not chew gum. Individuals who ingested soft drinks or juices were 2.30 times (95% CI =1.30–4.10 more likely to present dental erosion.Conclusion: The prevalence of erosion reflected the need for programs of prevention and guidance for patients about the etiological factors of the disease. Keywords: young adults, dental erosion, prevalence, factors, tooth wear, life style

  5. Dental erosion among 12-year-old schoolchildren: a population-based cross-sectional study in South Brazil.

    Science.gov (United States)

    Alves, Luana Severo; Brusius, Carolina Doege; Damé-Teixeira, Nailê; Maltz, Marisa; Susin, Cristiano

    2015-12-01

    To assess the epidemiology and risk indicators for dental erosion among 12-year-old schoolchildren in South Brazil. A population-based cross-sectional survey was conducted in Porto Alegre, Brazil, using a representative sample of 12-year-old schoolchildren (n = 1,528). Dental erosion was recorded according to the Basic Erosive Wear Examination (BEWE) index. Parents answered questions on socio-economic status, brushing frequency and general health. Schoolchildren answered questions on dietary habits. Anthropometric data were collected. Statistical analysis included logistic and Poisson regression models. The prevalence of dental erosion was 15% [95% confidence interval (95% CI): 13.6-16.5], being mainly mild erosion. Boys [odds ratio (OR) = 1.57, 95% CI: 1.17-2.10], private school attendees (OR = 1.45, 95% CI: 1.01-2.06) and schoolchildren reporting the daily consumption of soft drinks (OR = 5.04, 95% CI: 1.17-21.71) were more likely to have at least one tooth with dental erosion. Gender [boys, rate ratio (RR) = 1.66, 95% CI: 1.28-2.17], type of school (private, RR = 1.89, 95% CI: 1.53-2.35), the consumption of soft drinks (sometimes: RR = 5.27, 95% CI: 1.46-19.05; daily: RR = 6.82, 95% CI: 1.39-33.50) and the daily consumption of lemon (RR = 1.49, 95% CI: 1.11-2.00) were significantly associated with the number of affected surfaces. The present study found a moderate prevalence of dental erosion among young schoolchildren, with mild erosion being the most prevalent condition. Socio demographic variables and dietary habits were associated with dental erosion in this population. © 2015 FDI World Dental Federation.

  6. MR imaging of erosions in interphalangeal joint osteoarthritis: is all osteoarthritis erosive?

    International Nuclear Information System (INIS)

    Grainger, A.J.; Farrant, J.M.; O'Connor, P.J.; Tan, A.L.; Emery, P.; Tanner, S.; McGonagle, D.

    2007-01-01

    Erosive osteoarthritis is usually considered as an inflammatory subset of osteoarthritis (OA). However, an inflammatory component is now recognised in all subsets of OA, so this subgroup of erosive or inflammatory OA is more difficult to conceptualise. The aim of this study was to compare routine CR and MRI to investigate erosion numbers and morphology to determine whether hand OA in general is a more erosive disease than previously recognised. Fifteen patients with clinical (OA) of the small joints of the hand underwent MRI of one of the affected proximal interphalangeal (PIP) or distal interphalangeal (DIP) joints. Conventional radiographs (CR) of the hand were also obtained. The MR images were reviewed by two observers for the presence of central and marginal erosions. The site and morphology of any erosions was recorded. CR images of the same hand joint were scored independently for central and marginal erosions by the same observers. There was 100% agreement between the observers for scoring erosions on CR. Agreement for the MRI scores was also excellent (kappa = 0.84). MRI detected 37 erosions, of which only 9 were seen on CR. The increase in sensitivity using MRI was much greater for marginal erosions (1 detected on CR, 19 on MRI) than for central erosions (8 on CR, 18 on MRI). Using MRI 80% of joints examined showed 1 or more erosions compared with 40% using CR. If only marginal erosions were considered 80% of joints were still considered erosive by MRI criteria, but only 1 showed evidence of erosion on CR. Morphologically central erosions appeared to represent areas of subchondral collapse and pressure atrophy. In contrast, marginal erosions resembled those seen in inflammatory arthritides. Erosions, and particularly marginal erosions typical of those seen in inflammatory arthritis, are a more common feature of small joint OA than conventional radiographs have previously indicated. (orig.)

  7. Ion implantation method for preparing polymers having oxygen erosion resistant surfaces

    Science.gov (United States)

    Lee, Eal H.; Mansur, Louis K.; Heatherly, Jr., Lee

    1995-01-01

    Hard surfaced polymers and the method for making them are generally described. Polymers are subjected to simultaneous multiple ion beam bombardment, that results in a hardening of the surface, improved wear resistance, and improved oxygen erosion resistance.

  8. Dynamic SEM wear studies of tungsten carbide cermets

    Science.gov (United States)

    Brainard, W. A.; Buckley, D. H.

    1975-01-01

    Dynamic friction and wear experiments were conducted in a scanning electron microscope. The wear behavior of pure tungsten carbide and composite with 6 and 15 weight percent cobalt binder was examined. Etching of the binder was done to selectively determine the role of the binder in the wear process. Dynamic experiments were conducted as the WC and bonded WC cermet surfaces were transversed by a 50 micron radiused diamond stylus. These studies show that the predominant wear process in WC is fracture initiated by plastic deformation. The wear of the etched cermets is similar to pure WC. The presence of the cobalt binder reduces both friction and wear. The cementing action of the cobalt reduces granular separation and promotes a dense polished layer because of its low shear strength film-forming properties. The wear debris generated from unetched surface is approximately the same composition as the bulk.

  9. Erosion Protection for the AH-1G Low Radar Cross-Section Main Rotor Blade. Volume 1. Sand and Rain Erosion Evaluation

    Science.gov (United States)

    1977-01-01

    THIS PAGE (W7,o. D- el Ent .. d) __________________ PAGE READ INSTRUCTIONSREPO -PCUMENTATION PAEBEFORE COMPLETING FORM 2GOVT ACCESSIOR 3 RECIP11 ENUMBERc...the ultra-high molecular weight poly- ethylene by far in all aspects: 0• Rain erosion life • Sand erosion life Le12 * TIFO - -F 7 0 Wear patterns * Ease

  10. Predicting of soil erosion with regarding to rainfall erosivity and soil erodibility

    Science.gov (United States)

    Suif, Zuliziana; Razak, Mohd Amirun Anis Ab; Ahmad, Nordila

    2018-02-01

    The soil along the hill and slope are wearing away due to erosion and it can take place due to occurrence of weak and heavy rainfall. The aim of this study is to predict the soil erosion degree in Universiti Pertahanan Nasional Malaysia (UPNM) area focused on two major factor which is soil erodibility and rainfall erosivity. Soil erodibility is the possibilities of soil to detach and carried away during rainfall and runoff. The "ROM" scale was used in this study to determine the degree of soil erodibility, namely low, moderate, high, and very high. As for rainfall erosivity, the erosive power caused by rainfall that cause soil loss. A daily rainfall data collected from January to April was analyzed by using ROSE index classification to identify the potential risk of soil erosion. The result shows that the soil erodibilty are moderate at MTD`s hill, high at behind of block Lestari and Landslide MTD hill, and critical at behind the mess cadet. While, the highest rainfall erosivity was recorded in March and April. Overall, this study would benefit the organization greatly in saving cost in landslide protection as relevant authorities can take early measures repairing the most affected area of soil erosion.

  11. Simulation of surface wear by using a pin-on-disk tribometer, metallographic examination; Approche metallurgique par des essais de glissement sous faible charge de problemes d'usure rencontres en centrale

    Energy Technology Data Exchange (ETDEWEB)

    Brin, C.; Villain, J.P.; Riviere, J.P. [Poitiers Univ., 86 (France). Laboratoire de Metallurgie Physique UMR 6630 CNRS; Cauvin, R. [Electricite de France (EDF), 37 - Avoine (France). Groupe des Laboratoires

    1998-07-01

    Simple laboratory tests have been realized in water using a pin-on-disc tribometer under Hertz pressures well below the elastic limit of the 304 steel studied. The wear morphologies obtained under different experimental conditions (load, applied time, elimination or non-elimination of wear particles) always present a semi-periodic structure of tracks with small roughness. The structural (X-ray and TEM) characterizations reveal the existence of martensite, both in the degraded areas and in the wear particles. The track formation would result from the pulling out of particles, together with the local phase transformation of austenite into martensite under stresses, followed by the ploughing of the surface. The wear mechanism could be essentially attributed to mechanical and metallurgical effects. (authors)

  12. Wet-steam erosion of steam turbine disks and shafts

    International Nuclear Information System (INIS)

    Averkina, N. V.; Zheleznyak, I. V.; Kachuriner, Yu. Ya.; Nosovitskii, I. A.; Orlik, V. G.; Shishkin, V. I.

    2011-01-01

    A study of wet-steam erosion of the disks and the rotor bosses or housings of turbines in thermal and nuclear power plants shows that the rate of wear does not depend on the diagrammed degree of moisture, but is determined by moisture condensing on the surfaces of the diaphragms and steam inlet components. Renovating the diaphragm seals as an assembly with condensate removal provides a manifold reduction in the erosion.

  13. Erosion on spark plug electrodes; Funkenerosion an Zuendkerzenelektroden

    Energy Technology Data Exchange (ETDEWEB)

    Rager, J.

    2006-07-01

    Durability of spark plugs is mainly determined by spark gap widening, caused by electrode wear. Knowledge about the erosion mechanisms of spark plug materials is of fundamental interest for the development of materials with a high resistance against electrode erosion. It is therefore crucial to identify those parameters which significantly influence the erosion behaviour of a material. In this work, a reliable and reproducible testing method is presented which produces and characterizes electrode wear under well-defined conditions and which is capable of altering parameters specifically. Endurance tests were carried out to study the dependence of the wear behaviour of pure nickel and platinum on the electrode temperature, gas, electrode gap, electrode diameter, atmospheric pressure, and partial pressure of oxygen. It was shown that erosion under nitrogen is negligible, irrespective of the material. This disproves all common mechanism discussed in the literature explaining material loss of spark plug electrodes. Based on this observation and the variation of the mentioned parameters a new erosion model was deduced. This relies on an oxidation of the electrode material and describes the erosion of nickel and platinum separately. For nickel, electrode wear is caused by the removal of an oxide layer by the spark. In the case of platinum, material loss occurs due to the plasma-assisted formation and subsequent evaporation of volatile oxides in the cathode spot. On the basis of this mechanism a new composite material was developed whose erosion resistance is superior to pure platinum. Oxidation resistant metal oxide particles were added to a platinum matrix, thus leading to a higher erosion resistance of the composite. However, this can be decreased by a side reaction, the separation of oxygen from the metal oxides, which effectively assists the oxidation of the matrix. This reaction can be suppressed by using highly stable oxides, characterized by a large negative Gibbs

  14. Erosion behavior of EEDS cermet coatings

    International Nuclear Information System (INIS)

    Jin Guo; Xu Binshi; Wang Haidou; Yin Liang; Li Qingfen; Wei Shicheng; Cui Xiufang

    2008-01-01

    This paper investigates the erosion performance of electro-thermal explosion directional spraying (EEDS) cermet WC/Co coatings using an air solid particle erosion rig. The influences of the different parameters such as impact angle, impingement velocity, environment temperature, particle diameter, on the erosion property of the coatings were studied. The eroded surfaces were examined by scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS) and the erosion mechanisms were discussed. The structure and bond characters of the coatings were also determined by transmission electron microscopy (TEM), X-ray diffraction (XRD) and SEM. The results indicate that the EEDS WC/Co coatings are characterized by fine grain structure, good metallurgical bond and brittle erosion character. The erosion rates of the coatings decrease with temperature increasing and increase with impact angle and impingement velocity increasing. At elevated temperature, the oxidation happens on the coatings surface, which affects the erosion behavior

  15. Gastric Mucosal Erosions - Radiologic evaluation -

    International Nuclear Information System (INIS)

    Kim, Seung Hyup

    1985-01-01

    70 cases of gastric mucosal erosions were diagnosed by double contrast upper gastrointestinal examinations and endoscopic findings. Analyzing the radiologic findings of these 70 cases of gastric mucosal erosions, the following results were obtained. 1. Among the total 70 cases, 65 cases were typical varioliform erosions showing central depressions and surrounding mucosal elevations. Remaining 5 cases were erosions of acute phase having multiple irregular depressions without surrounding elevations. 2. The gastric antrum was involved alone or in part in all cases. Duodenal bulb was involved with gastric antrum in 4 cases. 3. The majority of the cases had multiple erosions. There were only 2 cases of single erosion. 4. In 65 cases of varioliform erosions; 1) The diameter of the surrounding elevations varied from 3 to 20 mm with the majority (47 cases) between 6 and 10 mm. 2) In general, the surrounding elevations with sharp margin on double contrast films were also clearly demonstrated on compression films but those with faint margin were not. 3) The size of the central barium collections varied from pinpoint to 10 mm with the majority under 5 mm. The shape of the central barium collections in majority of the cases were round with a few cases of linear, triangular or star-shape. 5. In 5 cases of acute phase erosions; 1) All the 5 cases were females. 2) On double contrast radiography, all the cases showed multiple irregular depressed lesions without surrounding elevations. 3) 1 case had the history of hematemesis. 4) In 1 case, there was marked radiological improvement on follow-up study of 2 months interval. 6. In 23 cases, there were coexistent diseases with gastric mucosal erosions. These were 13 cases of duodenal bulb ulcers,7 cases of benign gastric ulcers and 3 others

  16. Preliminary studies for monitoring erosion in pipelines by the acoustic emission technique

    Energy Technology Data Exchange (ETDEWEB)

    Tiboni, G.B. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil). Programa de Pos-graduacao em Engenharia Mecanica e de Materiais; Marquardt, T.A.S; SantaMaria, V.A.R.; Silva, C.H. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil)

    2009-07-01

    The aim of this work is to present some applications of Acoustic Emission (AE), which is a powerful technique for nondestructive testing in Tribology, treated here as tests of friction, wear by contact fatigue, wear by slip and wear by erosion. In this work a special attention is given to solid particle erosion and hydro-abrasive erosion, problems found in almost every pipeline that lead to local loss of material and eventually rupture of the line. The technique of AE can be used as an efficient online tool when, primarily, to monitor tribological aspects such as the rate of wear of materials, as well as detect the spread of flaws in them. In wear by erosion, specifically, the parameters of RMS and acoustic energy are capable of correlation with the type of mechanism for removal of material. As a preliminary goal, erosive tests were performed with gas (air) without erosive particles, monitored by AE, varying the surface of the samples and the internal diameter the nozzle, taking the differences in signs of AE. Correlation between parameters of RMS and amplitude were noticed with the variables of the tests, such as roughness and fluid velocity. The RMS parameter showed a exponential correction with the fluid velocity, however the amplitude signals had a linear behavior. The knowledge of these parameters is essential for the development of a system that is able to quantify the wear rate of a pipeline without taking it out of operation. (author)

  17. Sliding wear of cemented carbides

    International Nuclear Information System (INIS)

    Engqvist, H.; Ederyd, S.; Uhrenius, B.; Hogmark, S.

    2001-01-01

    Cemented carbides are known to be very hard and wear resistant and are therefor often used in applications involving surface damage and wear. The wear rate of cemented carbides is often measured in abrasion. In such tests it has been shown that the wear rate is inversely dependent on the material hardness. The sliding wear is even more of a surface phenomenon than a abrasion, making it difficult to predict friction and wear from bulk properties. This paper concentrates on the sliding wear of cemented carbides and elucidates some wear mechanisms. It is especially shown that a fragmenting wear mechanism of WC is very important for the description of wear of cemented carbides. (author)

  18. Wear Analysis of Wind Turbine Gearbox Bearings

    Energy Technology Data Exchange (ETDEWEB)

    Blau, Peter Julian [ORNL; Walker, Larry R [ORNL; Xu, Hanbing [ORNL; Parten, Randy J [ORNL; Qu, Jun [ORNL; Geer, Tom [ORNL

    2010-04-01

    The objective of this effort was to investigate and characterize the nature of surface damage and wear to wind turbine gearbox bearings returned from service in the field. Bearings were supplied for examination by S. Butterfield and J. Johnson of the National Wind Technology Center (NREL), Boulder, Colorado. Studies consisted of visual examination, optical and electron microscopy, dimensional measurements of wear-induced macro-scale and micro-scale features, measurements of macro- and micro-scale hardness, 3D imaging of surface damage, studies of elemental distributions on fracture surfaces, and examinations of polished cross-sections of surfaces under various etched and non-etched conditions.

  19. Dental caries and erosion status of 12-year-old Hong Kong children.

    Science.gov (United States)

    Zhang, Shinan; Chau, Alex Mh; Lo, Edward Cm; Chu, Chun-Hung

    2014-01-08

    This study aimed to assess the dental caries and erosion status of 12-year-old Hong Kong children and study the determinants of dental caries and dental erosion of these children. The survey was performed from 2011 to 2012 with ethics approval. Stratified random sampling was adopted to select 12-year-old children in 7 primary schools in Hong Kong. The participating parents were asked to complete a self-administered questionnaire concerning their children's diet and oral health habits. The children were examined for caries status with WHO criteria by 3 calibrated examiners. Detection of dental erosion followed Basic Erosive Wear Examination (BEWE) criteria. A total of 704 children were recruited and 600 (316 boys, 53%) participated in the survey. There were 124 children (21%) with caries experience (DMFT > 0) and their DMFT was 0.34 ± 0.76. About half of their decay was unfilled (DT = 0.16 ± 0.52) The DMFT of girls and boys were 0.45 ± 0.89 and 0.23 ± 0.61, respectively (p = 0.001). Girls also had a higher DT (0.21 ± 0.62 compared with 0.11 ± 0.41, p = 0.013) and FT than boys (0.23 ± 0.63 compared with 0.12 ± 0.44, p = 0.016). Most children (75%) had at least some sign of erosion (BEWE > 0), but no severe erosion (BEWE = 3). Logistic regression showed girls who consumed soft drinks and took vitamin C supplements had higher caries risk. Dental erosion was more severe among the children who had caries experience and consumed fruit juice. The 12-year-old Hong Kong children had low caries experience, and almost half of the decay was left untreated. Although severe erosion was not found, many children had early signs of erosion.

  20. Theory of powdery rubber wear.

    Science.gov (United States)

    Persson, B N J

    2009-12-02

    Rubber wear typically involves the removal of small rubber particles from the rubber surface. On surfaces with not too sharp roughness, e.g. most road surfaces, this involves (slow) crack propagation. In this paper I shall present a theory of mild rubber wear. I shall derive the distribution of wear particle sizes Φ(D), which is in excellent agreement with experiment. I shall also show that the calculated wear rate is consistent with experimental data for tire tread block wear.

  1. Theory of powdery rubber wear

    Energy Technology Data Exchange (ETDEWEB)

    Persson, B N J [IFF, FZ-Juelich, 52425 Juelich (Germany)

    2009-12-02

    Rubber wear typically involves the removal of small rubber particles from the rubber surface. On surfaces with not too sharp roughness, e.g. most road surfaces, this involves (slow) crack propagation. In this paper I shall present a theory of mild rubber wear. I shall derive the distribution of wear particle sizes PHI(D), which is in excellent agreement with experiment. I shall also show that the calculated wear rate is consistent with experimental data for tire tread block wear.

  2. Erosion-corrosion of 316 stainless steel rods immersed in a bubbling fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.Y.; Coronella, C.J.; Seader, J.D. (Utah Univ., Salt Lake City, UT (United States). Dept. of Chemical Engineering); Pitt, C.H. (Utah Univ., Salt Lake City, UT (United States). Dept. of Metallurgy and Metallurgical Engineering)

    1993-04-01

    A fluidized bed was operated in the bubbling regime with sand to determine the effects of process variables on in-bed metal wastage due to erosion and/or corrosion of immersed 316 stainless steel (SS) rods. Weight loss as a result of erosion was determined by conducting experiments with air at room temperature and high fluidizing velocities (erosion-dominated). Weight loss due mainly to corrosion was determined by carrying out wear tests at 500[sup o]C and relatively low gas velocity (corrosion-dominated). By comparing the total weight loss obtained from the tests at high temperature and high gas velocity conditions (erosion-corrosion-dominated) with the sum of weight losses from erosion-dominated and corrosion-dominated studies, it was found that there was a synergistic effect between corrosion and erosion, i.e. erosion and corrosion took place simultaneously and interacted in a way leading to accelerated wear of the 316 SS rods. The wear rates increased with increasing temperature and excess gas velocity and were also affected by rod orientation in that wear rates of vertical rods were less than those of horizontal rods under identical test conditions. In all cases, wear rates were less than 3.0 nm/h in the radial direction. (author)

  3. Fretting friction and wear characteristics of magnetorheological fluid under different magnetic field strengths

    International Nuclear Information System (INIS)

    Zhang, P.; Lee, K.H.; Lee, C.H.

    2017-01-01

    A magnetorheological fluid (MRF) performs differently under different magnetic field strength. This study examined the fretting friction and wear characteristics of MRFs under a range of magnetic field strengths and oscillation frequencies. The fretting friction and wear behaviors of MRF are investigated using a fretting friction and wear tester. The surfaces of specimen are examined by optical microscopy and 3D surface profilometer before and after the tests and wear surface profiles, the wear volume loss and wear coefficient for each magnetic field strength are evaluated. The results show that the friction and wear properties of MRF change according to the magnetic field strength and oscillation frequency. - Highlights: • Fretting friction and wear characteristics of MRF is examined. • The friction coefficients increased with increasing magnetic field strength. • The coefficient of friction decreased with increasing oscillation frequency. • Wear volume and coefficient become worse with increasing magnetic field strength.

  4. Simultaneous acid exposure and erosive particle wear of thermoset coatings

    DEFF Research Database (Denmark)

    Møller, Victor Buhl; Dam-Johansen, Kim; Frankær, Sarah Maria

    2018-01-01

    bottom-placed coating samples. Maximum rates were found about halfway between the reactor center and wall. Polishing rates also varied significantly with acid concentration, most likely due to chemical reactions taking place between the acid and the coatings, damaging surface mechanical properties...

  5. Erosive wear of a surface coated hydroturbine steel

    Indian Academy of Sciences (India)

    Administrator

    turbines, pipelines and valves used in slurry transporta- tion of matter, and fluidized bed combustion systems. (Kosel 1992). Coatings of wide variety of materials ... design of test rig can be found in an earlier paper (Chau- han et al 2008). The erodents were accelerated down a. 16 mm diameter stainless steel tube, 1 m in ...

  6. Wear Trends of the HERMeS Thruster as a Function of Throttle Point

    Science.gov (United States)

    Williams, George J., Jr.; Kamhawi, Hani; Choi, Maria; Haag, Thomas; Huang, Wensheng; Herman, Daniel A.; Gilland, James H.; Peterson, Peter Y.

    2017-01-01

    A series of short-duration (200 hour) wear tests were conducted with two Hall Effect Rocket with Magnetic Shielding (HERMeS) technology demonstration units (TDU). Front pole covers, cathode keeper, and discharge channel wear were characterized as a function of discharge voltage, magnetic field strength, and chamber pressure. No discharge channel erosion was observed. Inner pole cover erosion was shown to be a weak function of discharge voltage with most erosion occurring at the lowest value, 300 volts. The TDU-3 keeper electrode eroded with each operating condition, with high magnetic field yielding the greatest erosion rate. The TDU-1 keeper electrode exhibited net deposition suggesting its configuration is more consistent with meeting overall HERMeS service life requirements. Ratios of molybdenum to graphite erosion rates suggests, with high uncertainty, that the sputtering ions are originating downstream of the thruster exit plane, striking the surface with small angles of incidence.

  7. Effect of acidic agents on the wear behavior of a polymer infiltrated ceramic network (PICN) material.

    Science.gov (United States)

    Yu, Ping; Xu, Zhou; Arola, Dwayne D; Min, Jie; Zhao, Peng; Gao, Shanshan

    2017-10-01

    Polymer infiltrated ceramic network (PICN) materials exhibit desirable properties for replacement of tooth structure. However, their durability and their integrity in various oral environments, remain relatively unknown. The primary objective of this study is to investigate the effect of acidic agents on the wear behavior of PICNs. Twenty specimens were randomly assigned to four groups and then immersed in either deionized water (control) or acidic agents (2% acetic acid, citric acid or lactic acid solutions) at 37℃ for 4 weeks. Changes in the surface microhardness (SMH) and roughness were measured. Reciprocating wear tests were performed under artificial saliva to 10,000 cycles, and the coefficient of friction (COF) and wear depth were quantified to assess the wear behavior. Scanning electron microscopy (SEM) was used to analyze the wear morphology. Acid erosion decreased the SMH and increased surface roughness of the PICN, especially in lactic acid solution. For less than 2800 cycles, the acetic acid and citric acid groups showed higher COF and wear depths due to combined ceramic and polymer wear; the lactic acid group showed smaller COF and wear depth, due to a wear debris layer that acted as solid lubricant. Beyond 2800 cycles, all four groups exhibited similar COF values, as well as wear depth and wear morphology. Overall, acid erosion had a significant effect on the surface wear history of the PICN, but no effect on its long-term wear properties. Overall, the depth of acidic degradation of the PICN was rather limited. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Pseudomembranous candidiasis in patient wearing full denture

    Directory of Open Access Journals (Sweden)

    Nurdiana Nurdiana

    2009-06-01

    Full Text Available Background: Oral candidiasis is a common opportunistic infection of the oral cavity caused by an overgrowth of Candida species, the commonest being Candida albicans. Candida albicans is a harmless commensal organism inhabiting the mouths but it can change into pathogen and invade tissue and cause acute and chronic disease. Dentures predispose to infection with Candida in as many as 65% of elderly people wearing full upper dentures. Purpose: The purpose of this case report is to discuss thrush in patient wearing full denture which rapidly developed. Case: This paper report a case of 57 year-old man who came to the Oral Medicine Clinic Faculty of Dentistry Airlangga University with clinical appearance of pseudomembranous candidiasis (thrush. Case Management: Diagnosis of this case is confirmed with microbiology examination. Patient was wearing full upper dentures, and from anamnesis known that patient wearing denture for 24 hours and he had poor oral hygiene. Patient was treated with topical (nystatin oral suspension and miconazole oral gel and systemic (ketoconazole antifungal. Patient also instructed not to wear his denture and cleaned white pseudomembrane on his mouth with soft toothbrush. Conclusion: Denture, habit of wearing denture for 24 hours, and poor oral hygiene are predisposing factors of thrush and it can healed completely after treated with topical and systemic antifungal.

  9. Determination of a Wear Initiation Cycle by using a Contact Resistance Measurement in Nuclear Fuel Fretting

    International Nuclear Information System (INIS)

    Lee, Young Ho; Kim, Hyung Kyu

    2008-01-01

    In nuclear fuel fretting, the improving of the contact condition with a modified spring shape is a useful method for increasing the wear resistance of the nuclear fuel rod. This is because the fretting wear resistance between the fuel rod and grid spring is mainly affected by the grid spring shape rather than the environment, the contact modes, etc. In addition, the wear resistance is affected by the wear debris behavior between contact surfaces. So, it is expected that the wear initiation of each spring shape should be determined in order to evaluate a wear resistance. However, it is almost impossible to measure the wear behavior in contact surfaces on a real time basis because the contact surfaces are always hidden. Besides, the results of the worn surface observation after the fretting wear tests are restricted to archive the information on the wear debris behavior and the formation mechanism of the wear scar. In order to evaluate the wear behavior during the fretting wear tests, it is proposed that the contact resistance measurement is a useful method for examining the wear initiation cycle and modes. Generally, fretting wear damages are rapidly progressed by a localized plastic deformation between the contact surfaces, crack initiation and fracture of the deformed surface with a strain hardening difference between a surface and a subsurface and finally a detachment of wear debris. After this, wear debris is easily oxidized by frictional heat, test environment, etc. At this time, a small amount of electric current applied between the contact surfaces will be influenced by the wear debris, which could be an obstacle to an electric current flow. So, it is possible to archive the information on the wear behavior by measuring the contact resistance. In order to determine the wear initiation cycle during the fretting wear tests, in this study, fretting wear tests have been performed by applying a constant electric current in room temperature air

  10. Leading edge erosion of coated wind turbine blades: Review of coating life models

    NARCIS (Netherlands)

    Slot, H.M.; Gelinck, E.R.M.; Rentrop, A.; van der Heide, Emile

    2015-01-01

    Erosion of the leading edge of wind turbine blades by droplet impingement wear, reduces blade aerodynamic efficiency and power output. Eventually, it compromises the integrity of blade surfaces. Elastomeric coatings are currently used for erosion resistance, yet the life of such coatings cannot be

  11. The Effect of pH on Slurry Erosion-Corrosion of Tungsten Carbide Overlays Alloyed with Ru

    Science.gov (United States)

    Nelwalani, Ndivhuwo B.; van der Merwe, Josias W.

    2018-01-01

    The aim of the study was to determine the effect of Ru additions to WC-Fe overlays when exposed to low pH slurry erosion conditions. These overlays were applied through Plasma Transferred Arc, and the original bulk Ru powder concentrations varied from 0.5 to 5 wt.%. A slurry jet impingement erosion-corrosion test rig was used to evaluate wear, and electrochemical measurements were performed to characterize the corrosion properties. The slurry mixtures contained silica sand and synthetic mine water. The pH was varied between 3 and 6.5 for the slurry erosion tests and lowered further for the corrosion characterization. Samples were examined optically and with a scanning electron microscope using energy-dispersive x-ray spectroscopy. X-ray diffraction analysis was used to determine the phases present. For the slurry erosion-corrosion results at the pH of 6.5, addition of Ru did not show a decrease in erosion-corrosion rates. However, when the pH was decreased to 3, by the addition of HCl, Ru improved the resistance. From the electrochemistry, it was also clear that Ru additions improved the corrosion resistance, but more than 1 wt.% Ru was required. At very low pH levels, the presence of Ru was not able to prevent corrosion.

  12. The Effect of pH on Slurry Erosion-Corrosion of Tungsten Carbide Overlays Alloyed with Ru

    Science.gov (United States)

    Nelwalani, Ndivhuwo B.; van der Merwe, Josias W.

    2018-02-01

    The aim of the study was to determine the effect of Ru additions to WC-Fe overlays when exposed to low pH slurry erosion conditions. These overlays were applied through Plasma Transferred Arc, and the original bulk Ru powder concentrations varied from 0.5 to 5 wt.%. A slurry jet impingement erosion-corrosion test rig was used to evaluate wear, and electrochemical measurements were performed to characterize the corrosion properties. The slurry mixtures contained silica sand and synthetic mine water. The pH was varied between 3 and 6.5 for the slurry erosion tests and lowered further for the corrosion characterization. Samples were examined optically and with a scanning electron microscope using energy-dispersive x-ray spectroscopy. X-ray diffraction analysis was used to determine the phases present. For the slurry erosion-corrosion results at the pH of 6.5, addition of Ru did not show a decrease in erosion-corrosion rates. However, when the pH was decreased to 3, by the addition of HCl, Ru improved the resistance. From the electrochemistry, it was also clear that Ru additions improved the corrosion resistance, but more than 1 wt.% Ru was required. At very low pH levels, the presence of Ru was not able to prevent corrosion.

  13. Erosion-Oxidation Response of Boiler Grade Steels: A Mathematical Investigation

    Directory of Open Access Journals (Sweden)

    S. K. Das

    2008-01-01

    Full Text Available A ductile erosion model embodying the mechanisms of erosion involving cutting wear and repeated plastic deformation has been developed to predict erosion rates of boiler grade steels. The issue of erosion-oxidation interaction has also been addressed to further predict the mass loss resulted from this composite mechanism. A deterministic formalism for the kinetics of oxide-scale growth and a probabilistic approach to characterize the material loss are employed to describe simultaneous actions of high-temperature oxidation and mechanical erosion. The model predictions are in good agreement with the published data.

  14. Automated Erosion System to Protect Highway Bridge Crossings at Abutments

    Science.gov (United States)

    2010-06-01

    A new instrument (Photo-Electronic Erosion Pin, or PEEP) was examined in collecting field data and remotely monitoring bank erosion near bridge abutments during floods. The performance of PEEPs was evaluated through a detailed field study to determin...

  15. Varioliform erosions in the stomach and duodenum

    International Nuclear Information System (INIS)

    Lotz, W.; Schulz, D.; Munkel, G.

    1984-01-01

    One thousand five hundred and eighty-three patients who were x-rayed for dyspepsia showed varioliform erosions in 15.3%. Men had an incidence of 9.8%, almost twice as common as in women (5.5%). Mucosal polyps, usually of the hyperplastic type, occurred in 2.4%. 15% of patients with gastric ulcers and 16% of patients with duodenal ulcers had varioliform erosions. On the other hand, amongst patients with erosions, 11% had gastric ulcers and 8.3% duodenal ulcers. The definitions of erosion which have been given in the literature are partly contradictory, and are discussed. Varioliform erosions, also known as complete erosions, may be acute or chronic. They are the third most common cause of bleeding from the upper gastrointestinal tract. With modern radiological methods of examining the stomach, they are no longer a rare finding. (orig.) [de

  16. Comparative wear mapping techniques

    DEFF Research Database (Denmark)

    Alcock, J.; Sørensen, Ole Toft; Jensen, S.

    1996-01-01

    Pin surfaces were analysed by laser profilometry. Two roughness parameters, R(a) and the fractal dimension, were investigated as a first step towards methods of quantitative wear mechanism mapping. Both parameters were analysed for their relationship to the severity and prevalence of a mechanism....

  17. Influence of halogen irradiance on short- and long-term wear resistance of resin-based composite materials.

    LENUS (Irish Health Repository)

    Bhamra, Gurcharn S

    2009-02-01

    The Oregon Health Science University (OHSU) four-chamber oral wear simulator was used to examine the impact of halogen irradiance on the short- and long-term wear behavior of four-methacrylate resin-based composites (RBCs). The hypothesis proposed was that exacerbated wear would occur following the long-term wear of RBCs irradiated under non-optimized irradiance conditions.

  18. Assessment of wear facets produced by the ACTA wear machine

    DEFF Research Database (Denmark)

    Benetti, Ana R; Larsen, Liselotte; Dowling, Adam H

    2016-01-01

    the 2D profile technique ranks RBC materials in terms of in-vitro wear performance. CLINICAL SIGNIFICANCE: Confidence in the wear volume measurements can only be achieved if the wear facet is analysed with sufficient resolution using a 3D digital measurement technique. However, the employment of 2D....... The mean wear depth was measured using the traditionally employed 2D and compared with the 3D profilometric (digital) techniques. Data were submitted to analyses of variance, Tukey's post hoc tests and Independent Samples Student's t-tests (where appropriate) at p... for mean wear depth calculations were similar whether the 2D or 3D techniques were employed. However, the mean wear depth values obtained from the 3D digital technique were significantly increased for two of the five RBC materials compared with the 2D methodology. The total volumetric wear data provided...

  19. Sliding Wear and Fretting Wear of DLC-Based, Functionally Graded Nanocomposite Coatings

    Science.gov (United States)

    Miyoshi, K.; Pohlchuck, B.; Street, Kenneth W.; Zabinski, J. S.; Sanders, J. H.; Voevodin, A. a.; Wu, R. L. C.

    1999-01-01

    Improving the tribological functionality of diamondlike carbon (DLC) films--developing, good wear resistance, low friction, and high load-carrying capacity-was the aim of this investigation. Nanocomposite coatings consisting of an amorphous DLC (a-DLC) top layer and a functionally graded titanium-titanium carbon-diamondlike carbon (Ti-Ti(sub x) C(sub y)-DLC) underlayer were produced on AISI 440C stainless steel substrates by the hybrid technique of magnetron sputtering and pulsed-laser deposition. The resultant DLC films were characterized by Raman spectroscopy, scanning electron microscopy, and surface profilometry. Two types of wear experiment were conducted in this investioation: sliding friction experiments and fretting wear experiments. Unidirectional ball-on-disk sliding friction experiments were conducted to examine the wear behavior of an a-DLC/Ti-Ti(sub x) C(sub y)-DLC-coated AISI 440C stainless steel disk in sliding contact with a 6-mm-diameter AISI 440C stainless steel ball in ultrahigh vacuum, dry nitrogen, and humid air. Although the wear rates for both the coating and ball were low in all three environments, the humid air and dry nitrogen caused mild wear with burnishing, in the a-DLC top layer, and the ultrahigh vacuum caused relatively severe wear with brittle fracture in both the a-DLC top layer and the Ti-Ti(sub x) C(sub y)-DLC underlayer. For reference, amorphous hydrogenated carbon (H-DLC) films produced on a-DLC/Ti-Ti(sub x) C(sub y)-DLC nanocomposite coatings by using an ion beam were also examined in the same manner. The H-DLC films markedly reduced friction even in ultrahigh vacuum without sacrificing wear resistance. The H-DLC films behaved much like the a-DLC/Ti-Ti(sub x) C(sub y)-DLC nanocomposite coating in dry nitrogen and humid air, presenting low friction and low wear. Fretting wear experiments were conducted in humid air (approximately 50% relative humidity) at a frequency of 80 Hz and an amplitude of 75 micron on an a

  20. Erosion and Errors

    NARCIS (Netherlands)

    Huisman, H.; Heeres, Glenn; Os, van Bertil; Derickx, Willem; Schoorl, J.M.

    2016-01-01

    Slope soil erosion is one of the main threats to archaeological sites. Several methods were applied to establish the erosion rates at archaeological sites. Digital elevation models (DEMs) from three different dates were used. We compared the elevations from these three models to estimate erosion. We

  1. Assessing storm erosion hazards

    NARCIS (Netherlands)

    Ranasinghe, Ranasinghe W M R J B; Callaghan, D.; Ciavola, Paolo; Coco, Giovanni

    2017-01-01

    The storm erosion hazard on coasts is usually expressed as an erosion volume and/or associated episodic coastline retreat. The accurate assessment of present-day and future storm erosion volumes is a key task for coastal zone managers, planners and engineers. There are four main approaches that can

  2. Mapping erosion from space

    NARCIS (Netherlands)

    Vrieling, A.

    2007-01-01

    Soil erosion by water is the most important land degradation problem worldwide. Spatial information on erosion is required for defining effective soil and water conservation strategies. Satellite remote sensing can provide relevant input to regional erosion assessment. This thesis comprises a review

  3. Duke Power Company's control rod wear program

    International Nuclear Information System (INIS)

    Culp, D.C.; Kitlan, M.S. Jr.

    1990-01-01

    Recent examinations performed at several foreign and domestic pressurized water reactors have identified significant control rod cladding wear, leading to the conclusion that previously believed control rod lifetimes are not attainable. To monitor control rod performance and reduce safety concerns associated with wear, Duke Power Company has developed a comprehensive control rod wear program for Ag-In-Cd and boron carbide (B 4 C) rods at the McGuire and Catawba nuclear stations. Duke Power currently uses the Westinghouse 17 x 17 Ag-In-Cd control rod design at McGuire Unit 1 and the Westinghouse 17 x 17 hybrid B 4 C control rod design with a Ag-In-Cd tip at McGuire Unit 2 and Catawba Units 1 and 2. The designs are similar, with the exception of the absorber material and clad thickness. There are 53 control rods per unit

  4. Prevalence and distribution of tooth wear among Sri Lankan adolescents.

    Science.gov (United States)

    Ratnayake, Nilantha; Ekanayake, Lilani

    2010-01-01

    The aim of the present study was to assess the prevalence, distribution and sociodemographic factors associated with tooth wear among Sri Lankan adolescents. A total of 1200 17-year-olds were selected from government, private and international schools in the Colombo district of Sri Lanka using a two-stage cluster sampling technique. The data were collected using a pretested, validated self-administered questionnaire and by conducting a clinical examination. Tooth wear was recorded using a modified version of Smith and Knight's tooth wear index. The prevalence of tooth wear among Sri Lankan adolescents was found to be 22.4%. In nearly 13.7%, tooth wear was confined to the enamel, whereas 8.7% had wear lesions extending up to the dentine. Occlusal surface was the most frequently affected surface, while the first molar was the most frequently affected tooth. Tooth wear was significantly associated with the type of school attended, father's occupational status and mother's level of education. The present study found that nearly one-fourth of the adolescents were affected by tooth wear. These findings are in agreement with those from developed countries where tooth wear has been shown to be an emerging oral health problem.

  5. Slurry Erosion Studies on Surface Modified 13Cr-4Ni Steels: Effect of Angle of Impingement and Particle Size

    Science.gov (United States)

    Manisekaran, T.; Kamaraj, M.; Sharrif, S. M.; Joshi, S. V.

    2007-10-01

    Hydroturbine steels, such as 13Cr-4Ni martensitic steels, are generally subjected to heavy-erosive wear and loss of efficiency due to solid particulate entrainment in the water. Surface-modified steels have proven to give better performance in terms of erosive wear resistance. In the present study, an attempt is made to investigate the effect of angle of impingement and particle size on slurry-jet erosion behavior of pulsed plasma nitrided and laser hardened 13Cr-4Ni steels. Laser hardening process has shown good performance at all angles of impingement due to martensitic transformation of retained austenite. Plastic deformation mode of material removal was also an evident feature of all laser-hardened surface damage locations. However, pulsed-plasma nitrided steels have exhibited chip formation and micro-cutting mode of erosive wear. Erosion with 150-300 μm size was twice compared to 150 μm size slurry particulates.

  6. Millisecond bearing wear

    International Nuclear Information System (INIS)

    Blatchley, C.; Sioshansi, P.

    1987-01-01

    Radionuclides have been widely used for many purposes in medicine, metals, transportation, manufacturing and research. Approximately 200 artificially produced nuclides are commercially available from reactors or accelerator sources. Another 400 or so have properties which may make them useful if satisfactory methods of production can be developed. One of the most economically important industrial applications of radionuclides has been in wear measurement and condition monitoring in reciprocating engines. The general techniques developed for this purpose have also been applied in a number of other areas besides engine or lubrication studies. The wear of floor wax applied to linoleum, for example, has been measured by mixing shortlived radionuclides in the wax. In those applications where the material is tagged and then followed, the radionuclides are termed ''tracers,'' similar to the medical tracer materials used to measure uptake or metabolism of biologically active chemicals in the body. The alternate function for the radionuclides is to act as ''markers'' which indicate the amount of material which is remaining at the location of the original activation. Both approaches require that the debris removed from the surface must be carried away from the original site. The first application of radioactive tracers as a diagnostic tool in engines was in 1949. In this technique, an entire wearing part such as a piston ring or gear was first exposed to neutrons in a nuclear reactor. This caused the entire volume of the part to become radioactive. The part was next installed and exposed to wear in the operating engine. Detectors placed near the oil line, an oil filter or a sediment trap then determined the amount of debris from the part by counting the gamma rays escaping from the debris

  7. ESTUDIO DEL DESGASTE EROSIVO POR CAVITACIÓN DE UN ACERO AUSTENÍTICO DE ALTO NITRÓGENO APOYADO EN EL USO DE LA DIFRACCIÓN DE ELECTRONES RETROPROYECTADOS-EBSD ASSESSMENT OF CAVITATION-EROSION WEAR OF A HIGH NITROGEN AUSTENITIC STAINLESS STEEL FROM ELECTRON BACKSCATTERING DIFFRACTION-EBSD

    Directory of Open Access Journals (Sweden)

    Dairo Hernán Mesa Grajales

    2010-08-01

    Full Text Available Muestras de acero inoxidable con estructura austenítica y contenido aproximado de nitrógeno de 0,9% en peso en solución sólida fueron sometidas a ensayos de cavitación vibratoria en agua destilada, con el fin de estudiar la evolución del desgaste erosivo por cavitación (EC a escala del tamaño de grano (mesoescala. Las muestras fueron obtenidas por medio de nitruración gaseosa a alta temperatura (HTGN del acero inoxidable dúplex UNS S31803, las cuales fueron caracterizadas por difracción de electrones retroproyectados (EBSD, a fin de obtener información de la orientación cristalina de los granos en la superficie a ser cavitada. La técnica de microscopía electrónica de barrido (SEM, fue usada para acompañar el proceso de desgaste para diferentes tiempos de ensayo. Como resultados de los ensayos de cavitación se determinó la pérdida de masa y se hizo un estudio secuencial de la apariencia superficial de las muestras para determinar los mecanismos de desgaste operantes en cada etapa. Los resultados fueron analizados a la luz de la caracterización cristalográfica previa. Para propósitos de comparación, fue usado el acero austenítico convencional UNS S30403. A partir de los resultados se observó que tanto la nucleación del daño como su evolución se dan de forma heterogénea a escala del tamaño de grano, resultado atribuido a la anisotropía en la deformación plástica. El carácter heterogéneo del daño por cavitación fue atribuido principalmente a las características de los límites de grano y a la microtextura dentro de los granos.Stainless steel samples with 100% austenitic microstructure and alloyed with 0.9 wt-% of nitrogen in solid solution were tested under vibratory cavitation experiments in distilled water to study the cavitation-erosion wear (EC at grain size level (mesoscale. Fully austenitic samples were obtained by high temperature gas nitriding (HTGN a commercially available dúplex stainless steel, UNS

  8. The erosion performance of particle reinforced metal matrix composite coatings produced by co-deposition cold gas dynamic spraying

    Science.gov (United States)

    Peat, Tom; Galloway, Alexander; Toumpis, Athanasios; McNutt, Philip; Iqbal, Naveed

    2017-02-01

    This work reports on the erosion performance of three particle reinforced metal matrix composite coatings, co-deposited with an aluminium binder via cold-gas dynamic spraying. The deposition of ceramic particles is difficult to achieve with typical cold spray techniques due to the absence of particle deformation. This issue has been overcome in the present study by simultaneously spraying the reinforcing particles with a ductile metallic binder which has led to an increased level of ceramic/cermet particles deposited on the substrate with thick (>400 μm) coatings produced. The aim of this investigation was to evaluate the erosion performance of the co-deposited coatings within a slurry environment. The study also incorporated standard metallographic characterisation techniques to evaluate the distribution of reinforcing particles within the aluminium matrix. All coatings exhibited poorer erosion performance than the uncoated material, both in terms of volume loss and mass loss. The Al2O3 reinforced coating sustained the greatest amount of damage following exposure to the slurry and recorded the greatest volume loss (approx. 2.8 mm3) out of all of the examined coatings. Despite the poor erosion performance, the WC-CoCr reinforced coating demonstrated a considerable hardness increase over the as-received AA5083 (approx. 400%) and also exhibited the smallest free space length between adjacent particles. The findings of this study reveal that the removal of the AA5083 matrix by the impinging silicon carbide particles acts as the primary wear mechanism leading to the degradation of the coating. Analysis of the wear scar has demonstrated that the damage to the soft matrix alloy takes the form of ploughing and scoring which subsequently exposes carbide/oxide particles to the impinging slurry.

  9. Experimental Research on the Determination of the Coefficient of Sliding Wear under Iron Ore Handling Conditions

    Directory of Open Access Journals (Sweden)

    G. Chen

    2017-09-01

    Full Text Available The handling of iron ore bulk solids maintains an increasing trend due to economic development. Because iron ore particles have hard composites and irregular shapes, the bulk solids handling equipment surface can suffer from severe sliding wear. Prediction of equipment surface wear volume is beneficial to the efficient maintenance of worn areas. Archard’s equation provides a theoretical solution to predict wear volume. To use Archard’s equation, the coefficient of sliding wear must be determined. To our best knowledge, the coefficient of sliding wear for iron ore handling conditions has not yet been determined. In this research, using a pin-on-disk tribometer, the coefficients of sliding wear for both Sishen particles and mild steel are determined with regard to iron ore handling conditions. Both naturally irregular and spherical shapes of particles are used to estimate average values of wear rate. Moreover, the hardness and inner structures of Sishen particles are examined, which adds the evidence of the interpretation of wear results. It is concluded that the coefficients of sliding wear can vary largely for both Sishen particle and mild steel. The wear rate decreases from transient- to steady-state. The average coefficient of sliding wear is capable of predicting wear with respect to long distances at the steady-state. Two types of sliding friction are distinguished. In addition, it is found that the temperature rise of the friction pairs has negligible influence on wear rate.

  10. Edge loading has a paradoxical effect on wear in metal-on-polyethylene total hip arthroplasties.

    Science.gov (United States)

    Harris, William H

    2012-11-01

    Edge wear is an adverse factor that can negatively impact certain THAs. In some metal-on-metal THAs, it can lead to adverse tissue reactions including aseptic lymphocytic vasculitis-associated lesions and even to pseudotumor formation. In some ceramic-on-ceramic THAs, it can lead to squeaking and/or stripe wear. Edge wear in metal-on-metal and ceramic-on-ceramic THAs can also be associated with accelerated wear across the articulation of these joints. I asked: Does edge wear occur in metal-on-polyethylene (MOP) articulations? And if so, does it increase joint wear? I examined the evidence in the literature for edge wear occurring in MOP THA and then assessed the evidence in the literature for data supporting the concept that edge wear in MOP hips could accelerate wear across the articulation over time. Extensive data in the literature confirm edge wear is common in MOP THA. Surprisingly, the evidence does not support that it accelerates wear across the articulation. In fact, substantial data support the concept that it does not. These observations suggest, in terms of edge wear accelerating overall wear, MOP articulation may have a privileged position compared to hard-on-hard THA articulations.

  11. Investigation of friction and wear characteristics of palm biodiesel

    International Nuclear Information System (INIS)

    Fazal, M.A.; Haseeb, A.S.M.A.; Masjuki, H.H.

    2013-01-01

    Highlights: ► Both wear and friction decrease with the increase of biodiesel concentration. ► Wear and friction appear to decrease more at the range of 10–20% biodiesel in diesel blend. ► The wear of steel ball in biodiesel (B100) was 20% lower than that in diesel (B0). ► Lubricity in terms of wear and friction decreases with the increase of rotating speed. - Abstract: Use of biodiesel in automobile engine is creating tribology related new challenges. The present study aims to assess the friction and wear characteristics of palm biodiesel at different concentration level by using four-ball wear machine. The investigated fuels were biodiesel (B100), diesel (B0) and three different biodiesel blends such as B10 (10% biodiesel in diesel), B20, B50. Tests were conducted at 75 °C under a normal load of 40 kg for 1 h at four different speeds viz, 600, 900, 1200 and 1500 rpm. Worn surfaces of the balls were examined by SEM. Results showed that wear and friction decreased with the increase of biodiesel concentration. The wear of steel ball in B100 was appeared to be 20% lower than that in diesel (B0)

  12. Catalytic interface erosion

    International Nuclear Information System (INIS)

    Meng, H.; Cohen, E.G.D.

    1995-01-01

    We study interface erosion processes: catalytic erosions. We present two cases. (1) The erosion of a completely occupied lattice by one single moving particle starting from somewhere inside the lattice, considering deterministic as well as probabilistic erosion rules. In the latter case, the eroded regions appear to have interfaces with continuously tunable fractal dimensions. (2) The kinetic roughening of an initially flat surface, where ballistic or diffusion-limited particles, which remain intact themselves, erode the surface coming from the outside, using the same erosion rules as in (1). Many features resembling realistic interfaces, for example, islands and inlets, are generated. The dependence of the surface width on the system size is due to both the erosion mechanism and the way particles move before reaching the surface

  13. Advanced Wear-resistant Nanocomposites for Increased Energy Efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Cook, B. A.; Harringa, J. L.; Russel, A. M.

    2012-12-01

    This report summarizes the work performed by an Ames-led project team under a 4-year DOE-ITP sponsored project titled, 'Advanced Wear-resistant Nanocomposites for Increased Energy Efficiency.' The Report serves as the project deliverable for the CPS agreement number 15015. The purpose of this project was to develop and commercialize a family of lightweight, bulk composite materials that are highly resistant to degradation by erosive and abrasive wear. These materials, based on AlMgB{sub 14}, are projected to save over 30 TBtu of energy per year when fully implemented in industrial applications, with the associated environmental benefits of eliminating the burning of 1.5 M tons/yr of coal and averting the release of 4.2 M tons/yr of CO{sub 2} into the air. This program targeted applications in the mining, drilling, machining, and dry erosion applications as key platforms for initial commercialization, which includes some of the most severe wear conditions in industry. Production-scale manufacturing of this technology has begun through a start-up company, NewTech Ceramics (NTC). This project included providing technical support to NTC in order to facilitate cost-effective mass production of the wear-resistant boride components. Resolution of issues related to processing scale-up, reduction in energy intensity during processing, and improving the quality and performance of the composites, without adding to the cost of processing were among the primary technical focus areas of this program. Compositional refinements were also investigated in order to achieve the maximum wear resistance. In addition, synthesis of large-scale, single-phase AlMgB{sub 14} powder was conducted for use as PVD sputtering targets for nanocoating applications.

  14. Friction and wear calculation methods

    CERN Document Server

    Kragelsky, I V; Kombalov, V S

    1981-01-01

    Friction and Wear: Calculation Methods provides an introduction to the main theories of a new branch of mechanics known as """"contact interaction of solids in relative motion."""" This branch is closely bound up with other sciences, especially physics and chemistry. The book analyzes the nature of friction and wear, and some theoretical relationships that link the characteristics of the processes and the properties of the contacting bodies essential for practical application of the theories in calculating friction forces and wear values. The effect of the environment on friction and wear is a

  15. Wear of polymers and composites

    CERN Document Server

    Abdelbary, Ahmed

    2015-01-01

    In the field of tribology, the wear behaviour of polymers and composite materials is considered a highly non-linear phenomenon. Wear of Polymers and Composites introduces fundamentals of polymers and composites tribology. The book suggests a new approach to explore the effect of applied load and surface defects on the fatigue wear behaviour of polymers, using a new tribometer and thorough experiments. It discusses effects of surface cracks, under different static and cyclic loading parameters on wear, and presents an intelligent algorithm, in the form of a neural network, to map the relations

  16. Biotribology of Cartilage Wear in Knee and Hip Joints Review of Recent Developments

    Science.gov (United States)

    Gulsen, Akdogan; Merve, Goncu; Meltem, Parlak

    2018-01-01

    Nowadays, the problem of wear in the knee and hip joints is an important issue that concerns many people and still requires new solutions. In recent years, researchers dealing with knee and hip articular cartilage erosion continue to investigate the subject in terms of biotribology. In this study, recent developments and studies in this relevant area are been examined. By using the basic principles of tribology, useful new methods that can be used in the field of biotribology can be produced. Artificial joints designed using various materials such as metals, ceramics, polymers and composites are still being studied. New studies in this area will affect the development of implant technology. Different alloys or composites are currently being tested for new implant designs. Moving implants with a risk of wear are tested in laboratory conditions in simulator devices before they are used in the human body. Major topics such as nanotechnology, tissue engineering, orthopedics, tribology, biotribology, lubrication, organ transplantation and artificial organs, which are still important today, will be useful in the search for finding suitable solutions in the future in biotribological studies. This review article aims to provide an overview of in-vitro studies at the theoretical and laboratory conditions that must be performed prior to clinical investigation.

  17. Pure mechanical wear loss measurement in corrosive wear

    Indian Academy of Sciences (India)

    Unknown

    Jiang Xiaoxia 1992 Metall. Sinica 28 B57. Jiang Xiaoxia and Li Sizuo 1991 Chemical Machinery 18 150. (in Chinese). Madson B W 1988 Wear 123 127. Pitt C H 1986 Corrosion 42 312. Schumacher W 1985 Wear of Materials 558. Tomlison W J 1991 Tribo. Inter. 2 67. Yue Zhongying 1987 Solid Lubrication 7 65 (in Chinese).

  18. Pure mechanical wear loss measurement in corrosive wear

    Indian Academy of Sciences (India)

    The method for the measurement of the pure mechanical wear loss for 321 stainless steel, 1045 steel and pure iron in the study of the synergy between corrosion and wear was studied. The methods studied included the measurement in distilled water, by cathodic protection and by adding inhibitor KI, and all were ...

  19. Numerical Analysis of Erosion Caused by Biomimetic Axial Fan Blade

    Directory of Open Access Journals (Sweden)

    Jun-Qiu Zhang

    2013-01-01

    Full Text Available Damage caused by erosion has been reported in several industries for a wide range of situations. In the present work, a new method is presented to improve the erosion resistance of machine components by biomimetic method. A numerical investigation of solid particle erosion in the standard and biomimetic configuration blade of axial fan is presented. The analysis consists in the application of the discrete phase model, for modeling the solid particles flow, and the Eulerian conservation equations to the continuous phase. The numerical study employs computational fluid dynamics (CFD software, based on a finite volume method. User-defined function was used to define wear equation. Gas/solid flow axial fan was simulated to calculate the erosion rate of the particles on the fan blades and comparatively analyzed the erosive wear of the smooth surface, the groove-shaped, and convex hull-shaped biomimetic surface axial flow fan blade. The results show that the groove-shaped biomimetic blade antierosion ability is better than that of the other two fan blades. Thoroughly analyze of antierosion mechanism of the biomimetic blade from many factors including the flow velocity contours and flow path lines, impact velocity, impact angle, particle trajectories, and the number of collisions.

  20. Protection from erosion following wildfire

    Science.gov (United States)

    Peter R. Robichaud; William J. Elliot

    2006-01-01

    Erosion in the first year after a wildfire can be up to three orders of magnitude greater than the erosion from undisturbed forests. To mitigate potential postfire erosion, various erosion control treatments are applied on highly erodible areas with downstream resources in need of protection. Because postfire erosion rates generally decline by an order of magnitude for...

  1. [Infants wearing teething necklaces].

    Science.gov (United States)

    Taillefer, A; Casasoprana, A; Cascarigny, F; Claudet, I

    2012-10-01

    Numerous infants wear teething necklaces, a quack remedy with a real risk of strangulation or aspiration of small beads. Evaluate parental perceptions and beliefs about the use of teething necklaces and analyze parental knowledge about the associated dangers. Between March and July 2011, in three different pediatric units of a tertiary children's hospital and a general hospital in Toulouse and Montauban (southwest France), voluntary parents were invited to be interviewed about their child wearing a teething necklace. The interviews were conducted following an anthropological approach: they were recorded and then fully transcribed and analyzed. Parents were informed that the conversation was recorded. During the study period, 48 children were eligible. Eleven families refused to participate, 29 parents were interviewed face to face. The children's mean age was 14 years ± 7 months, the male:female ratio was equal to 0.8 (12 boys, 15 girls). The mean age of children when necklace wearing was started was equal to 4 ± 2 months. The mean mother's age was 31 ± 5 years and 33 ± 4 years for fathers. The parents' religion was mostly Catholic (60%). Teething necklaces were mainly made of amber (n=23). Sales information about the risks associated with the necklaces was for the most part absent (92%). The most frequent positive parental perceptions were analgesic properties and a soothing remedy (73%); a birth accessory and memory (64%); an esthetic accessory (60%); a protective amulet (60%); and an alternative or additional element to other traditional therapeutics (55%). The negative parental perceptions (n=4) were an unnecessary accessory, costume jewelry, a pure commercial abuse of a popular belief, a dangerous item with a risk of strangulation, and the absence of proof of its efficacy. Although parents concede that teeth eruption is benign, they fear its related symptoms. To a natural phenomenon a natural response: they use a necklace to satisfy the analogy. The

  2. Tyre and road wear prediction

    NARCIS (Netherlands)

    Lupker, H.A.

    2003-01-01

    Both tyre wear and road polishing are complex phenomenon, which are obviously strongly related; the energy that polishes the road is the energy that wears the tyre. The both depend non-linearly on numerous parameters, like materials used, vehicle and road usage, environmental conditions (i.e.

  3. A clinical index for evaluating and monitoring dental erosion

    DEFF Research Database (Denmark)

    Larsen, I B; Westergaard, J; Stoltze, K

    2000-01-01

    This study describes a new fine-scaled system for classifying initial and advanced dental erosions. The system includes the use of study casts of the teeth in an epoxy resin with an accurate surface reproduction. The severity of erosion on each tooth surface is scored according to six grades...... of severity. In addition, the presence of a Class V restoration and dental erosion on the same surface increases the erosion score, as it is assumed that the need for restorative treatment can be caused by the erosion. A high inter-examiner agreement was found when the present scoring system was used by two...

  4. Abrasive wear response of aluminium alloy-sillimanite particle reinforced composite under low stress condition

    International Nuclear Information System (INIS)

    Singh, M.; Mondal, D.P.; Das, S.

    2006-01-01

    The abrasive wear behaviour of aluminium alloy-sillimanite particle reinforced composite under low stress condition has been reported and the results have been compared with the corresponding matrix alloy which was produced and cast under similar conditions. The study showed that wear resistance (inverse of wear rate) of the composite was higher than the matrix alloy. The wear rate decreased with sliding distance and increased with applied load irrespective of materials. The worn surfaces and subsurfaces of the tested samples were examined in the scanning electron microscope in order to understand the material removal mechanism during low stress abrasive wear process

  5. Prolonging contact lens wear and making contact lens wear safer.

    Science.gov (United States)

    Foulks, Gary N

    2006-02-01

    To summarize the present status of safety and efficacy of contact lens wear. Literature review. Ovid Medline searches were performed on records from 1966 through 2005 using keywords: keratitis, contact lens complications, extended-wear contact lenses, and silicone-hydrogel contact lenses. Patients desire comfort, clarity of vision, and prolonged contact lens wear when contact lenses are used to correct refractive error. Practitioners desire patient satisfaction but also require maintenance of the integrity of the eye and no complications that jeopardize vision or health of the eye. Improvements in the oxygen permeability of the contact lens materials, design of the contact lens and its surface, and solutions for the maintenance of the lens have reduced but not eliminated the risks of infection, inflammation, and conjunctival papillary reaction associated with contact lens wear. The lessons of past and recent history suggest that patient education and practitioner participation in the management of contact lens wear continue to be critical factors for patient satisfaction and safety in the extended wear of contact lenses. The availability of highly oxygen permeable contact lenses has increased the tolerance and safety of extended contact lens wear, but patient instruction and education in proper use and care of lenses is required and caution is advised.

  6. Optimization of pulsed DC PACVD parameters: Toward reducing wear rate of the DLC films

    Science.gov (United States)

    Ebrahimi, Mansoureh; Mahboubi, Farzad; Naimi-Jamal, M. Reza

    2016-12-01

    The effect of pulsed direct current (DC) plasma-assisted chemical vapor deposition (PACVD) parameters such as temperature, duty cycle, hydrogen flow, and argon/CH4 flow ratio on the wear behavior and wear durability of the diamond-like carbon (DLC) films was studied by using response surface methodology (RSM). DLC films were deposited on nitrocarburized AISI 4140 steel. Wear rate and wear durability of the DLC films were examined with the pin-on-disk method. Field emission scanning electron microscopy, Raman spectroscopy, and nanoindentation techniques were used for studying wear mechanisms, chemical structure, and hardness of the DLC films. RSM results show that duty cycle is one of the important parameters that affect the wear rate of the DLC samples. The wear rate of the samples deposited with a duty cycle of >75% decreases with an increase in the argon/CH4 ratio. In contrast, for a duty cycle of <65%, the wear rate increases with an increase in the argon/CH4 ratio. The wear durability of the DLC samples increases with an increase in the duty cycle, hydrogen flow, and argon/CH4 flow ratio at the deposition temperature between 85 °C and 110 °C. Oxidation, fatigue, abrasive wear, and graphitization are the wear mechanisms observed on the wear scar of the DLC samples deposited with the optimum deposition conditions.

  7. Pipe bend wear - is tungsten carbide the answer?

    International Nuclear Information System (INIS)

    Freinkel, D.

    1988-01-01

    The purpose of the investigation was to compare the relative wear resistance of various grades of sintered tungsten carbide liners against a mild steel standard in a full-scale pneumatic conveying testing rig. Speciments ranging in cobalt content from 6 to 30 per cent and in grain size from 0,56 to 2,98 microns, including a mild steel standard, were placed on a specially designed holder which fitted into a tee type 100 mm diameter bend. The specimens were tested under various operating conditions, ie air velocity ranging from 28m/s to 52m/s, impact angles of 30 0 to 70 0 mass flow rates of 35kg/min to 83kg/min and phase densities of 1,2 to 2,9, using a 4 mm nominal size crushed granite rock. The experimental results show that the ultrafine-grained, low cobalt (6 per cent) tungsten carbide displays little sensitivity to varying velocities, impact angles, mass flow rates or phase densities, and consistently gave the best wear resistance under all testing conditions. It consistently showed the least wear resistance under all testing conditions and performed only slightly better than mild steel. The effect of the carbide grain size was found to be small, although the finer grain sizes displayed greater wear resistance than the coarse grains. The effect of cobalt content was such that the lower cobalt specimens (6 per cent range) consistently performed better than the higher cobalt contents (10 per cent, 15 per cent, 30 per cent) under all testing conditions; the wear resistance decreasing with increasing cobalt content. An empirical model for the prediction of wear for each type of material tested has been proposed, given the particular operating conditions. Microstructurally it has been shown that there is a definite relationship between erosion resistance and the inverse of the magnetic coercivity of the tungsten carbide alloys

  8. Use of microhardness as a simple means of estimating relative wear resistance of carbide thermal spray coatings: Part 2. wear resistance of cemented carbide coatings

    Science.gov (United States)

    Factor, Michael; Roman, Itzhak

    2002-12-01

    A selection of WC-Co and Cr3C2-25%NiCr coatings produced by plasma spray and high velocity oxygen fuel (HVOF) deposition techniques were subjected to various wear tests designed to simulate abrasion, cavitation, sliding, and particle erosion type wear mechanisms. All of the coatings were at least 200 µm thick and were deposited onto stainless steel substrates. In Part 1 of this contribution, the microstructures of the coatings were characterized and their mechanical properties were assessed using microindentation procedures. In this second part of the article, the behavior of the coatings when subjected to the various wear tests is reported and the utility of microhardness testing as an indication of relative wear resistance is discussed. It is shown that correctly performed, appropriate microhardness measurements are a good indication of abrasion resistance and sliding wear resistance, and also correlate well with cavitation resistance in Cr3C2-NiCr. The measurements were less useful for predicting erosion resistance for both Cr3C2-NiCr and WC-Co, however, and for abrasion resistance when WC-Co was ground against SiC. Here the contribution of micromechanisms involving fracturing and brittle failure is greater than that indicated by the coating microhardness, which is essentially a measurement of resistance to plastic deformation under equilibrium conditions.

  9. Pyrroloquinoline quinine inhibits RANKL-mediated expression of NFATc1 in part via suppression of c-Fos in mouse bone marrow cells and inhibits wear particle-induced osteolysis in mice.

    Directory of Open Access Journals (Sweden)

    Lingbo Kong

    Full Text Available The effects of pyrroloquinoline quinine (PQQ on RANKL-induced osteoclast differentiation and on wear particle-induced osteolysis were examined in this study. PQQ inhibited RANKL-mediated osteoclast differentiation in bone marrow macrophages (BMMs in a dose-dependent manner without any evidence of cytotoxicity. The mRNA expression of c-Fos, NFATc1, and TRAP in RANKL-treated BMMs was inhibited by PQQ treatment. Moreover, RANKL-induced c-Fos and NFATc1 protein expression was suppressed by PQQ. PQQ additionally inhibited the bone resorptive activity of differentiated osteoclasts. Further a UHMWPE-induced murine calvaria erosion model study was performed to assess the effects of PQQ on wear particle-induced osteolysis in vivo. Mice treated with PQQ demonstrated marked attenuation of bone erosion based on Micro-CT and histologic analysis of calvaria. These results collectively suggested that PQQ demonstrated inhibitory effects on osteoclast differentiation in vitro and may suppress wear particle-induced osteolysis in vivo, indicating that PQQ may therefore serve as a useful drug in the prevention of bone loss.

  10. Dermatologists wearing white coats on practice websites: current trends.

    Directory of Open Access Journals (Sweden)

    Ryan G. Gamble

    2011-06-01

    Full Text Available Physicians wearing white coats are perceived as having more authority, being more friendly and being more attractive than those not wearing white coats, and patients report that they prefer their dermatologist to wear a white coat. The aim of the present study is to determine the prevalence of dermatologists wearing white coats on practice websites. We searched Google for dermatology practice websites in six states representing distinct geographic regions in the United States. The first one hundred search results were evaluated, and photographs of dermatologists on these websites were examined for the presence or absence of white coats. Most (77% of dermatologists did not wear white coats. The highest prevalence was in the eastern states of Massachusetts and South Carolina, with 29% and 39%, respectively. Colorado had the lowest rate at 13%. Rates were essentially equal when segmented by gender. Although patients report that they prefer their dermatologist to wear a white coat, dermatologists often do not wear a white coat on their practice websites.

  11. Simulation of erosion in drilling tools for oil and gas industry

    Energy Technology Data Exchange (ETDEWEB)

    Arefi, B.; Settari, A. [Calgary Univ., AB (Canada); Angman, P. [Tesco Corp., Calgary, AB (Canada)

    2004-07-01

    Erosion in oil well drilling tools is a form of wear which occurs when fluid containing solid particles impacts a solid surface. The intensity of erosion is generally measured as the rate of material removal from the surface, and is expressed as E{sub r}, the weight of material removed by unit weight of impacting particles. Erosion can also be reduced by tool improvement and modification, thereby extending the life of drilling tools. To date, no attempt has been made to model the erosion phenomenon in drilling tools. This paper presents a newly developed erosion simulator which is the first design tool for the drilling industry. This work demonstrates that erosion can be simulated. A model was developed to calibrate the erosion coefficients for drilling tool conditions. The mechanism of erosion can be controlled by the impact velocity and angle. Algorithms were developed for transient simulation of the erosion of any surface in 2-dimensional geometry. The Erosion Simulator has been validated and calibrated against data provided by TESCO Corporation's casing drilling tools. The model has been shown to successfully predict and minimize erosion by modifying the tool geometry and metallurgy. 21 refs., 1 tab., 15 figs.

  12. Erosion in America

    Energy Technology Data Exchange (ETDEWEB)

    1984-03-23

    The US loses about five billion tons of soil a year from erosion, and scientists estimate that from 20 to 50% of world cropland suffers from excessive erosion. The effect of erosion is a loss in both land and water productivity. When combined with the problems of overpopulation, overgrazing, and deforestation, the environmental impacts are very serious. There are some signs that countries are beginning to adopt conservation tilling techniques, but even cooperative government programs in the US such as the 1983 Payment-in-Kind (PIK) program have had only partial success because of expanded production on marginal farmlands. 20 reference 5 figures.

  13. Rubber glove wearing device

    International Nuclear Information System (INIS)

    Nozaki, Tatsuo; Takada, Kaoru.

    1994-01-01

    Rubber groves are attached each to an upper end of a glove putting vessel having an air-sucking hole on the bottom by enlarging an opening end of the rubber glove and turning back the inside to the outside. When the sucking device is operated, air in the glove putting device is sucked and the rubber glove is expanded by an atmospheric pressure. After expansion of the rubber glove to some extent, the sucking device is stopped, and presence or absence of failures of the rubber glove is confirmed by shrinkage of the rubber glove and by an indication value of a pressure gauge for detecting the pressure change in the vessel. Then, a hand is inserted to the expanded rubber glove, and a detaching switch in the vessel is pushed by a finger tip. A detaching piece at the upper end of the vessel is protruded outwardly to enlarge the turned-back portion of the rubber glove to easily release the rubber glove from the putting vessel, and the rubber glove is put on. This enables to wear the rubber glove and conduct failure test simultaneously. Further, a user can put on the rubber glove without touching the outside of the rubber glove. (I.N.)

  14. Nanoscale friction and wear maps.

    Science.gov (United States)

    Tambe, Nikhil S; Bhushan, Bharat

    2008-04-28

    Friction and wear are part and parcel of all walks of life, and for interfaces that are in close or near contact, tribology and mechanics are supremely important. They can critically influence the efficient functioning of devices and components. Nanoscale friction force follows a complex nonlinear dependence on multiple, often interdependent, interfacial and material properties. Various studies indicate that nanoscale devices may behave in ways that cannot be predicted from their larger counterparts. Nanoscale friction and wear mapping can help identify some 'sweet spots' that would give ultralow friction and near-zero wear. Mapping nanoscale friction and wear as a function of operating conditions and interface properties is a valuable tool and has the potential to impact the very way in which we design and select materials for nanotechnology applications.

  15. Measurement of erosion: Is it possible?

    NARCIS (Netherlands)

    Stroosnijder, L.

    2005-01-01

    Reasons for erosion measurements are: (1) to determine the environmental impact of erosion and conservation practices, (2) scientific erosion research; (3) development and evaluation of erosion control technology; (4) development of erosion prediction technology and (5) allocation of conservation

  16. Water droplet erosion of stainless steel steam turbine blades

    Science.gov (United States)

    Kirols, H. S.; Kevorkov, D.; Uihlein, A.; Medraj, M.

    2017-08-01

    Steam turbine blades are highly subjected to water droplet erosion (WDE) caused by high energy impingement of liquid water droplets. However, most of the published research on this wear phenomenon is performed on laboratory test rigs, instead of addressing WDE of actual steam turbine blades. In this work, the progression of erosion on the surface of ex-service low pressure steam turbine blades was investigated using scanning electron microscopy. The erosion appearance and mechanisms are compared with laboratory test rig results that are carried out using a rotating disk rig according to ASTM G73 standard. Initial and advanced erosion stages could be observed on the steam turbine blades. Similar to the WDE rig coupons, initial pits and cracks were preceded by blade surface roughening through the formation of asperities and depressions. In addition, it was also observed that the twist angle of the turbine blade around its diagonal, is an important parameter that influences its WDE. Twist angle has an effect on: impact angle, erosion appearance, impact speed, and the affected area. Furthermore, according to the current experimental results, multi-ray rig erosion test results are considered the closest simulation to the actual ex-service blade in terms of damage appearance.

  17. Wear mechanisms of coated hardmetals

    International Nuclear Information System (INIS)

    Richter, V.

    2001-01-01

    In the paper several aspects of the wear mechanisms of coated hardmetals, ceramics and super-hard materials (CBN) in machining cast iron are discussed, with particular attention being given to high-speed machining of different cast iron grades. The influence of machining parameters, microstructure, composition and mechanical and chemical properties of the cutting tool and the work-piece material on wear are considered. (author)

  18. Does Canoeing Increase Streambank Erosion?

    Science.gov (United States)

    Edward A. Hansen

    1975-01-01

    Describes research on the Pine River in Michigan to determine if large increases in canoeing accelerated streambank erosion. Most erosion was natural, but people sliding and camping on streambanks created some erosion. Heavy canoe traffic was not a cause of erosion.

  19. Wear behaviour of Al 261

    Directory of Open Access Journals (Sweden)

    N. Mathan Kumar

    2016-03-01

    Full Text Available Al 2618 matrix material was mixed with the Silicon Nitride (Si3N4, Aluminium Nitride (AlN and Zirconium Boride (ZrB2 reinforced particles. AMC was synthesized successfully by the stir casting method with the various X-wt.% of reinforcements (X = 0,2,4,6,8. Tribological behaviour was studied in this composite with various temperature conditions. The working conditions were Temperature (°C, Load (N, Velocity (m/s and Sliding Distances (m. Before wear testing the mechanical behaviour has been analysed. EDAX was confirmed by the matrix material composition. The Al 2618 alloy and the reinforcement mixers were confirmed by the X-ray Diffraction analysis. Wear rate (mm3/m, Wear resistance (m/mm3, Specific Wear rate (m/Nm and Co-efficient of friction (μ were analysed with various conditions. The worn surfaces were analysed before and after wear testing by Scanning Electron Microscope (SEM. Influence of process parameters and Percentage of contribution were analysed by Taguchi and Analysis of Variance (ANOVA methods. Genetic Algorithm (GA was adopted for optimizing the best and mean of the wear rate and to identify the exact influence of input parameters.

  20. On inhibition of dental erosion.

    Science.gov (United States)

    Rölla, Gunnar; Jonski, Grazyna; Saxegaard, Erik

    2013-11-01

    To examine the erosion-inhibiting effect of different concentrations of hydrofluoric acid. Thirty-six human molars were individually treated with 10 ml of 0.1 M citric acid for 30 min (Etch 1), acid was collected and stored until analysis. The teeth were randomly divided into six groups and then individually treated with 10 ml of one of six dilutions (from 0.1-1%) of hydrofluoric acid. The teeth were then again treated with citric acid (Etch 2). The individual acid samples from Etch 1 and 2 were analyzed for calcium by flame atomic absorption spectroscopy and difference in calcium loss was calculated. The highest erosion inhibiting effect was obtained in groups with the highest concentrations of hydrofluoric acid, where the pH was lowest, below pKa of 3.17, thus the hydrofluoric acids being mainly in an undissociated state. Diluted hydrofluoric acid is present in aqueous solution of SnF2 and TiF4 (which are known to inhibit dental erosion): SnF2 + 3H2O = Sn(OH)2 + 2HF + H2O and TiF4 + 5H2O = Ti(OH)4 + 4HF + H2O. It is also known that pure, diluted hydrofluoric acid can inhibit dental erosion. Teeth treated with hydrofluoric acid are covered by a layer of CaF2-like mineral. This mineral is acid resistant at pH acid resistant mineral, initiated by tooth enamel treatment with hydrofluoric acid. Hydrofluoric acid is different in having fluoride as a conjugated base, which provides this acid with unique properties.

  1. Critical component wear in heavy duty engines

    CERN Document Server

    Lakshminarayanan, P A

    2011-01-01

    The critical parts of a heavy duty engine are theoretically designed for infinite life without mechanical fatigue failure. Yet the life of an engine is in reality determined by wear of the critical parts. Even if an engine is designed and built to have normal wear life, abnormal wear takes place either due to special working conditions or increased loading.  Understanding abnormal and normal wear enables the engineer to control the external conditions leading to premature wear, or to design the critical parts that have longer wear life and hence lower costs. The literature on wear phenomenon r

  2. Rainfall erosivity in Europe.

    Science.gov (United States)

    Panagos, Panos; Ballabio, Cristiano; Borrelli, Pasquale; Meusburger, Katrin; Klik, Andreas; Rousseva, Svetla; Tadić, Melita Perčec; Michaelides, Silas; Hrabalíková, Michaela; Olsen, Preben; Aalto, Juha; Lakatos, Mónika; Rymszewicz, Anna; Dumitrescu, Alexandru; Beguería, Santiago; Alewell, Christine

    2015-04-01

    Rainfall is one the main drivers of soil erosion. The erosive force of rainfall is expressed as rainfall erosivity. Rainfall erosivity considers the rainfall amount and intensity, and is most commonly expressed as the R-factor in the USLE model and its revised version, RUSLE. At national and continental levels, the scarce availability of data obliges soil erosion modellers to estimate this factor based on rainfall data with only low temporal resolution (daily, monthly, annual averages). The purpose of this study is to assess rainfall erosivity in Europe in the form of the RUSLE R-factor, based on the best available datasets. Data have been collected from 1541 precipitation stations in all European Union (EU) Member States and Switzerland, with temporal resolutions of 5 to 60 min. The R-factor values calculated from precipitation data of different temporal resolutions were normalised to R-factor values with temporal resolutions of 30 min using linear regression functions. Precipitation time series ranged from a minimum of 5 years to a maximum of 40 years. The average time series per precipitation station is around 17.1 years, the most datasets including the first decade of the 21st century. Gaussian Process Regression (GPR) has been used to interpolate the R-factor station values to a European rainfall erosivity map at 1 km resolution. The covariates used for the R-factor interpolation were climatic data (total precipitation, seasonal precipitation, precipitation of driest/wettest months, average temperature), elevation and latitude/longitude. The mean R-factor for the EU plus Switzerland is 722 MJ mm ha(-1) h(-1) yr(-1), with the highest values (>1000 MJ mm ha(-1) h(-1) yr(-1)) in the Mediterranean and alpine regions and the lowest (<500 MJ mm ha(-1) h(-1) yr(-1)) in the Nordic countries. The erosivity density (erosivity normalised to annual precipitation amounts) was also the highest in Mediterranean regions which implies high risk for erosive events and floods

  3. Evaluation of the serum zinc level in erosive and non-erosive oral lichen planus.

    Science.gov (United States)

    Gholizadeh, N; Mehdipour, M; Najafi, Sh; Bahramian, A; Garjani, Sh; Khoeini Poorfar, H

    2014-06-01

    Lichen planus is a chronic inflammatory immunologic-based disease involving skin and mucosa. This disease is generally divided into two categories: erosive and non-erosive. Many etiologic factors are deliberated regarding the disease; however, the disorders of immune system and the role of cytotoxic T-lymphocytes and monocytes are more highlighted. Zinc is an imperative element for the growth of epithelium and its deficiency induces the cytotoxic activity of T-helper2 cells, which seems to be associated with lichen planus. This study was aimed to evaluate the levels of serum zinc in erosive and non-erosive oral lichen planus (OLP) and to compare it with the healthy control group to find out any feasible inference. A total of 22 patients with erosive oral lichen planus, 22 patients with non erosive OLP and 44 healthy individuals as the control group were recruited in this descriptive-comparative study. All the participants were selected from the referees to the department of oral medicine, school of dentistry, Tabriz University of Medical Sciences. Serum zinc level was examined for all the individuals with liquid-stat kit (Beckman Instruments Inc.; Carlsbad, CA). Data were analyzed by adopting the ANOVA and Tukey tests, using SPSS 16 statistical software. The mean age of patients with erosive and non-erosive LP was 41.7 and 41.3 years, respectively. The mean age of the healthy control group was 34.4 years .The mean serum zinc levels in the erosive and non erosive lichen planus groups and control groups were 8.3 (1.15), 11.15 (0.92) and 15.74 (1.75) μg/dl respectively. The difference was statistically significant (plichen planus. This finding may probably indicate the promising role of zinc in development of oral lichen planus.

  4. An Evaluation of High Velocity Wear

    Science.gov (United States)

    2007-03-01

    Stachowiak (Ed.), Wear: Materials, Mechanisms and Practice. Chichester, England: John Wiley and Sons. 10. Hooser, M. (2007). Rail dimensions...NV, 10-13 Jan 2000. , AIAA 2000-0155 13. Hutchings, I. M. (2005). The Challenge of Wear. In G. W. Stachowiak (Ed.), Wear: Materials, Mechanisms and...Kato, K. (2005). Classification of Wear Mechanisms/Models. In G. W. Stachowiak (Ed.), Wear: Materials, mechanisms and practice. Chichester, England

  5. Abrasion-erosion resistance of concrete made with two aggregates, Stonewall Jackson Dam, West Virginia

    Science.gov (United States)

    Holland, T. C.

    1983-09-01

    The resistance to abrasion-erosion of two concretes made with different coarse aggregates was evaluated. The aggregates used were selected as being representative of those that may be selected for use during construction of Stonewall Jackson Dam. The two coarse aggregates were limestones from different sources. All other concrete ingredients were identical for the two mixtures. Both concretes showed very high abrasion-erosion losses when tested using the Corps of Engineers standard test method. A recommendation was made that coarse aggregates with better wear-resistant properties be selected for use in areas of the structure that may be subjected to abrasion-erosion.

  6. An Iterative Method for Estimating Airfoil Deformation due to Solid Particle Erosion

    Directory of Open Access Journals (Sweden)

    Valeriu DRAGAN

    2014-04-01

    Full Text Available Helicopter blades are currently constructed with composite materials enveloping honeycomb cores with only the leading and trailing edges made of metal alloys. In some cases, the erosive wear of the bound between the composite skin and metallic leading edge leads to full blade failure. It is therefore the goal of this paper to provide a method for simulating the way an airfoil is deformed through the erosion process. The method involves computational fluid dynamics simulations, scripts for automatic meshing and spreadsheet calculators for estimating the erosion and, ultimately, the airfoil deformation. Further work could include more complex meshing scripts allowing the use of similar methods for turbo-machineries.

  7. Wear behavior of human enamel against lithium disilicate glass ceramic and type III gold.

    Science.gov (United States)

    Lee, Ahreum; Swain, Michael; He, Lihong; Lyons, Karl

    2014-12-01

    The wear behavior of human enamel that opposes different prosthetic materials is still not clear. The purpose of this in vitro study was to investigate and compare the friction and wear behavior of human tooth enamel that opposes 2 indirect restorative materials: lithium disilicate glass ceramic and Type III gold. Friction-wear tests on human enamel (n=5) that opposes lithium disilicate glass ceramic (n=5) and Type III gold (n=5) were conducted in a ball-on-flat configuration with a reciprocating wear testing apparatus. The wear pairs were subjected to a normal load of 9.8 N, a reciprocating amplitude of approximately 200 μm, and a reciprocating frequency of approximately 1.6 Hz for up to 1100 cycles per test under distilled water lubrication. The frictional force of each cycle was recorded, and the corresponding friction coefficient for different wear pairs was calculated. After wear testing, the wear scars on the enamel specimens were examined under a scanning electron microscope. Type III gold had a significantly lower steady-state friction coefficient (P=.009) and caused less wear damage on enamel than lithium disilicate glass ceramic. Enamel that opposed lithium disilicate glass ceramic exhibited cracks, plow furrows, and surface loss, which indicated abrasive wear as the prominent wear mechanism. In comparison, the enamel wear scar that opposed Type III gold had small patches of gold smear adhered to the surface, which indicated a predominantly adhesive wear mechanism. A lower friction coefficient and better wear resistance were observed when human enamel was opposed by Type III gold than by lithium disilicate glass ceramic in vitro. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  8. Ultrasonic measurement of enamel thickness : a tool for monitoring dental erosion?

    NARCIS (Netherlands)

    Huysmans, MCDNJM; Thijssen, JM

    Objectives: Wear of dental hard tissues, e.g. dental erosion, is reported to be a growing problem. A non-destructive measurement of enamel layer thickness would provide the opportunity for both early diagnosis, and longitudinal measurement of progressive enamel loss. It was the aim of this study to

  9. Adhesion and wear properties of boro-tempered ductile iron

    International Nuclear Information System (INIS)

    Kayali, Yusuf; Yalcin, Yilmaz; Taktak, Suekrue

    2011-01-01

    Highlights: → In this study, the wear and adhesion properties of BDI were investigated. → Boro-tempering process under several heat treatment conditions was examined. → Optical microscope, SEM and XRD analysis were carried out to investigate the microstructure. → It was observed that boro-tempering process improves micro-hardness and wear properties of ductile irons. -- Abstract: In this study, adhesion and wear properties of boro-tempered ductile iron (BDI) were investigated. Boro-tempering was carried out on two stage processes i.e. boronizing and tempering. At the first stage, ductile iron samples were boronized by using pack process at 900 o C for 1, 3, and 5 h and then, secondly tempered at 250, 300, 350, and 400 o C for 1 h. X-ray diffraction (XRD) analysis of boro-tempered samples showed that FeB and Fe 2 B phases were found on the surface of the samples. The Daimler-Benz Rockwell-C adhesion test was used to assess the adhesion of boride layer. Test result showed that adhesion decreased with increasing boriding time and increased with increasing tempering temperature. Dry sliding wear tests of these samples were performed against Al 2 O 3 ball at a constant sliding speed and loads of 5 and 10 N. Wear tests indicated that boro-tempering heat treatment increased wear resistance of ductile iron. In addition, it was found that while wear rate of boro-tempered samples decreased with increasing boriding time, there is no significant affect of tempering temperature on wear rate.

  10. Wear Assessment of Conical Pick used in Coal Cutting Operation

    Science.gov (United States)

    Dewangan, Saurabh; Chattopadhyaya, Somnath; Hloch, Sergej

    2015-09-01

    Conical pick is a widely used tool for cutting coal in mines. It has a cemented carbide tip inserted in a steel body. Cemented carbide has been in use for many years for coal/rock cutting because it has the optimum combination of hardness, toughness and resistance against abrasive wear. As coal/rock is a heterogeneous substance, the cutting tool has to undergo various obstructions at the time of excavation that cause the tool to wear out. The cracks and fractures developing in the cemented carbide limit the life of the tool. For a long time, different wear mechanisms have been studied to develop improved grades of cemented carbide with high wear resistance properties. The research is still continuing. Moreover, due to the highly unpredictable nature of coal/rock, it is not easy to understand the wear mechanisms. In the present work, an attempt has been made to understand the wear mechanisms in four conical picks, which were used in a continuous miner machine for underground mining of coal. The wearing pattern of the conical pick indicates damage in its cemented carbide tip as well as the steel body. The worn out parts of the tools have been critically examined using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) point analysis. Mainly four types of wear mechanisms, namely, coal/rock intermixing, plastic deformation, rock channel formation and crushing and cracking, have been detected. The presence of coal/rock material and their respective concentrations in the selected area of worn out surface were observed using the spectra generated by EDX analysis.

  11. The Effect of Nodular Cast Iron Metal Matrix on the Wear Resistance

    OpenAIRE

    G. Gumienny

    2012-01-01

    The paper presents results of studies on the effect of the nodular cast iron metal matrix composition on the abrasive and adhesive wear resistance. Nodular cast iron with different metal matrix obtained in the rough state and ADI were tested. To research of abrasive and adhesive wear the pearlitic and bainitic cast iron with carbides and without this component were chosen. The influence of the carbides amount for cast iron wear resistance was examined. It was found, that the highest abrasive ...

  12. Tool wear of a single-crystal diamond tool in nano-groove machining of a quartz glass plate

    International Nuclear Information System (INIS)

    Yoshino, Masahiko; Nakajima, Satoshi; Terano, Motoki

    2015-01-01

    Tool wear characteristics of a diamond tool in ductile mode machining are presented in this paper. Nano-groove machining of a quartz glass plate was conducted to examine the tool wear rate of a single-crystal diamond tool. Effects of lubrication on the tool wear rate were also evaluated. A numerical simulation technique was developed to evaluate the tool temperature and normal stress acting on the wear surface. From the simulation results it was found that the tool temperature does not increase during the machining experiment. It is also demonstrated that tool wear is attributed to the abrasive wear mechanism, but the effect of the adhesion wear mechanism is minor in nano-groove machining. It is found that the tool wear rate is reduced by using water or kerosene as a lubricant. (paper)

  13. Impact of tillage erosion on water erosion in a hilly landscape.

    Science.gov (United States)

    Wang, Y; Zhang, J H; Zhang, Z H; Jia, L Z

    2016-05-01

    Little has been known of the interaction between tillage erosion and water erosion, while the two erosion processes was independently studied. Can tillage-induced soil redistribution lead to exaggerated (or retarded) runoff flow and sediment concentrations in steeply sloping fields? A series of simulated tillage and artificial rainfall events were applied to rectangular runoff plots (2m×8m) with a slope of 15° to examine the impacts of tillage erosion intensities on water erosion in the Yangtze Three Gorges Reservoir Area, China. Mean flow velocity, effective/critical shear stress, and soil erodibility factor K were calculated to analyze the differences in hydrodynamic characteristics induced by tillage. Our experimental results suggest that mean runoff rates were 2.26, 1.19, and 0.65Lmin(-1) and that mean soil detachment rates were 1.53, 1.01, and 0.61gm(-2)min(-1) during the 70-min simulated rainfall events for 52-, 31-, and 10-year tillage, respectively. A significant difference (Pwater losses tended to increase with increasing tillage intensity. A significant difference in mean flow velocity occurred near the upper and lower slope boundaries of the field, while significant differences (Perosion increases soil erodibility and delivers the soil for water erosion in sloping fields, accelerating water erosion. Copyright © 2016. Published by Elsevier B.V.

  14. Statistical investigations into the erosion of material from the tool in micro-electrical discharge machining

    DEFF Research Database (Denmark)

    Puthumana, Govindan

    2018-01-01

    current (Id) and discharge frequency (fd) control the erosion of material from the tool electrode. The material erosion from the tool electrode (Me) increases linearly with the discharge frequency. As the current index increases from 20 to 35, the Me decreases linearly by 29%, and then increases by of 36......%. The current index of 35 gives the minimum material erosion from the tool. It is observed that none of the two-factor interactions are significant in controlling the erosion of the material from the tool.......This paper presents a statistical study of the erosion of material from the tool electrode in a micro-electrical discharge machining process. The work involves analysis of variance and analysis of means approaches on the results of the tool electrode wear rate obtained based on design...

  15. Erosion resistance and adhesion of composite metal/ceramic coatings produced by plasma spraying

    International Nuclear Information System (INIS)

    Ramm, D.A.J.; Hutchings, I.M.; Clyne, T.W.

    1993-01-01

    Ceramic coatings can exhibit greater erosion resistance than most metallic coatings. Such coatings are conveniently produced by thermal spraying. Unfortunately, thermally sprayed ceramic coatings often exhibit poor adhesion, partly as a consequence of the development of residual stresses during spraying and subsequent cooling. Composite coatings have been studied using aluminium/alumina deposits on steel substrates. The incorporation of ceramics within a ductile matrix has potential for sharply reducing the erosive wear at high erodent impact angles, whilst retaining the good erosion resistance of ceramics at low angles. It is shown that the proportion of metal and ceramic at the free surface can be specified so as to optimise the erosion resistance. Experiments have also been carried out on the resistance of the coatings to debonding during four-point bending of the coated substrate. Progress is being made towards the tailoring of composition profiles in graded coatings so as to optimise the combination of erosion resistance and adhesion. (orig.)

  16. CFD Based Erosion Modelling of Abrasive Waterjet Nozzle using Discrete Phase Method

    International Nuclear Information System (INIS)

    Kamarudin, Naqib Hakim; Prasada Rao, A K; Azhari, Azmir

    2016-01-01

    In Abrasive Waterjet (AWJ) machining, the nozzle is the most critical component that influences the performance, precision and economy. Exposure to a high speed jet and abrasives makes it susceptible to wear erosion which requires for frequent replacement. The present works attempts to simulate the erosion of the nozzle wall using computational fluid dynamics. The erosion rate of the nozzle was simulated under different operating conditions. The simulation was carried out in several steps which is flow modelling, particle tracking and erosion rate calculation. Discrete Phase Method (DPM) and K-ε turbulence model was used for the simulation. Result shows that different operating conditions affect the erosion rate as well as the flow interaction of water, air and abrasives. The simulation results correlates well with past work. (paper)

  17. Study on Sand Erosion and Tribological Behavior of TiO₂ Films Prepared on a Glass Surface.

    Science.gov (United States)

    Zhang, Bo; Wang, Junzhong; Shi, Zhiming; Liu, Quansheng; Ji, Guojun

    2018-03-01

    TiO2 films with one, three or five layers were prepared on a glass surface using the sol-gel method. The crystal structure, the surface morphology and the thickness of the films were characterized by X-ray diffraction, atomic force microscopy and ellipsometry. The tribological properties of the TiO2 films were investigated by a tribometer. TiO2 thin films were eroded by sand-air injection. The erosion behavior and mechanism of TiO2 thin films in a sandstorm were analyzed by scanning electron microscopy. The results showed that the films were highly abraded with increased erosion speed and dose of sand. With an increase in film layers, the erosion resistance and wear resistance of the TiO2 films increased gradually. The erosion mechanism consists of the film being damaged mainly from the cutting action of micro-scratches from low angle erosion. Alternatively, for high angle erosion, the material is damaged mainly by squeeze deformation by the action of erosion. Because of the high strength and toughness of the TiO2 thin films, the wear of its coating from high angle erosion is more severe than that from low erosion angle.

  18. Erosive Lichen Planus.

    Science.gov (United States)

    Mauskar, Melissa

    2017-09-01

    Lichen planus is an inflammatory mucocutaneous condition with a myriad of clinical manifestations. There are 3 forms of lichen planus that effect the vulva: papulosquamous, hypertrophic, and erosive. Erosive lichen planus can progress to vulvar scaring, vaginal stenosis, and squamous cell carcinoma; these long-term sequelae cause sexual distress, depression, and decreased quality of life for patients. Diagnosis is often delayed because of patient embarrassment or clinician misdiagnosis. Early recognition and treatment is essential to decreasing the morbidity of this condition. Multimodal treatment, along with a multidisciplinary approach, will improve outcomes and further clinical advances in studying this condition. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Abrasive Wear Properties of Fe-Based Alloys Designed for Mining Applications

    Directory of Open Access Journals (Sweden)

    Wieczorek A. N.

    2017-09-01

    Full Text Available The purpose of this study was to determine experimentally the wear properties of 5 groups of iron-based alloys used in the mining and transport machines exposed to the action of a hard abrasive material. The groups of materials to be examined included austempered ductile irons (ADI, steels and cast steel designed for quenching and tempering and for surface hardening, hard-wearing hardened steels and structural steels. The wear tests were carried out on a disc-on-disc test rig. The test samples were examined under conditions of sliding mating, while the leading destructive process was microcutting of the surface with loose corundum grain. The loss of mass of the examined samples was measured as a parameter characterizing the wear. Base on it, other wear coefficients were determined, for example the volume loss, the intensity of wear and the wear rate. The volume loss values determined were presented as a function of the strength and the initial hardness. Based on the results obtained, it was found that the hardened steel and ADI had comparable wear properties, while the ADI surface was strengthened probably as a result of the transition of austenite into martensite and the impact of the deformation of the graphite contained in ADI on the abrasive wear of the surface.

  20. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro

    2016-01-06

    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict and avoid them. In this work [4], we model the wear process using a pure jump process. Therefore, the inference goal here is to estimate: the number of possible jumps, its sizes, the coefficients and the shapes of the jump intensities. We propose a multiscale approach for the inference problem that can be seen as an indirect inference scheme. We found that using a Gaussian approximation based on moment expansions, it is possible to accurately estimate the jump intensities and the jump amplitudes. We obtained results equivalent to the state of the art but using a simpler and less expensive approach.

  1. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro

    2015-01-07

    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict and avoid them. In this work [4], we model the wear process using a pure jump process. Therefore, the inference goal here is to estimate: the number of possible jumps, its sizes, the coefficients and the shapes of the jump intensities. We propose a multiscale approach for the inference problem that can be seen as an indirect inference scheme. We found that using a Gaussian approximation based on moment expansions, it is possible to accurately estimate the jump intensities and the jump amplitudes. We obtained results equivalent to the state of the art but using a simpler and less expensive approach.

  2. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro

    2014-01-06

    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict and avoid them. In this work [4], we model the wear process using a pure jump process. Therefore, the inference goal here is to estimate: the number of possible jumps, its sizes, the coefficients and the shapes of the jump intensities. We propose a multiscale approach for the inference problem that can be seen as an indirect inference scheme. We found that using a Gaussian approximation based on moment expansions, it is possible to accurately estimate the jump intensities and the jump amplitudes. We obtained results equivalent to the state of the art but using a simpler and less expensive approach.

  3. Gastroesophageal Reflux is Not Associated with Dental Erosion in Children

    Science.gov (United States)

    Wild, Yvette K.; Heyman, Melvin B.; Vittinghoff, Eric; Dalal, Deepal H.; Wojcicki, Janet M.; Clark, Ann L.; Rechmann, Beate; Rechmann, Peter

    2011-01-01

    Background & Aims Dental erosion is a complication of gastroesophageal reflux (GER) in adults; in children, it is not clear if GER has a role in dental pathologic conditions. Dietary intake, oral hygiene, high bacterial load, and decreased salivary flow might contribute independently to GER development or dental erosion, but their potential involvement in dental erosion from GER is not understood. We investigated the prevalence of dental erosion among children with and without GER symptoms, and whether salivary flow rate or bacterial load contribute to location-specific dental erosion. Methods We performed a cross-sectional study of 59 children (ages 9–17 y) with symptoms of GER and 20 asymptomatic children (controls); all completed a questionnaire on dietary exposure. Permanent teeth were examined for erosion into dentin, erosion locations, and affected surfaces. The dentist was not aware of GER status, nor was the gastroenterologist aware of dental status. Stimulated salivary flow was measured and salivary bacterial load was calculated for total bacteria, Streptococcus mutans and Lactobacilli. Results Controlling for age, dietary intake, and oral hygiene, there was no association between GER symptoms and dental erosion, by tooth location or affected surface. Salivary flow did not correlate with GER symptoms or erosion. Erosion location and surface were independent of total bacteria and levels of Streptococcus mutans and Lactobacilli. Conclusions Location-specific dental erosion is not associated with GER, salivary flow, or bacterial load. Prospective studies are required to determine the pathogenesis of GER-associated dental erosion and the relationship between dental caries to GER and dental erosion. PMID:21820389

  4. Plasma Plume Characterization of the HERMeS During a 1722-hr Wear Test Campaign

    Science.gov (United States)

    Huang, Wensheng; Williams, George J.; Peterson, Peter Y.; Kamhawi, Hani; Gilland, James H.; Herman, Daniel A.

    2017-01-01

    A 1722-hr wear test campaign of NASA's 12.5-kW Hall Effect Rocket with Magnetic Shielding was completed. This wear test campaign, completed in 2016, was divided into four segments including an electrical configuration characterization test, two short duration tests, and one long wear test. During the electrical configuration characterization test, the plasma plume was examined to provide data to support the down select of the electrical configuration for further testing. During the long wear tests, the plasma plume was periodically examined for indications of changes in thruster behavior. Examination of the plasma plume data from the electrical configuration characterization test revealed a correlation between the plume properties and the presence of a conduction path through the front poles. Examination of the long wear test plasma plume data revealed that the plume characteristics remained unchanged during testing to within the measurement uncertainty.

  5. Calculation of wear (f.i. wear modulus) in the plastic cup of a hip joint prosthesis

    NARCIS (Netherlands)

    Ligterink, D.J.

    1975-01-01

    The wear equation is applied to the wear process in a hip joint prosthesis and a wear modulus is defined. The sliding distance, wear modulus, wear volume, wear area, contact angle and the maximum normal stress were calculated and the theoretical calculations applied to test results. During the wear

  6. Bentonite erosion. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Birgersson, Martin; Boergesson, Lennart; Hedstroem, Magnus; Karnland, Ola; Nilsson, Ulf (Clay Technology AB, Lund (Sweden))

    2009-12-15

    Low saline water may reach KBS-3 repository depth, e.g. during periods of glaciation. Under such aqueous conditions, the montmorillonite part of the bentonite buffer might transform into a sol and thereby be transported away with flowing water in fractures. The primary aim with this report is to improve the understanding of the basic principles for this possible montmorillonite particle release. The report includes experimental and theoretical work performed at Clay Technology. Natural bentonite and ion-exchanged purified montmorillonite from three different geographical origins, Wyoming (U.S.), Milos (Greece) and Kutch (India) have been studied. Experimental and/or theoretical investigations have been performed with respect to: - Free swelling ability; - Rheological properties; - Rate of bentonite loss into fractures; - Filtering; - Ion exchange; - Sol formation ability; - Ion diffusion; - Mass loss due to erosion. The performed erosion experiments show that erosion does not occur in a mixed calcium/sodium montmorillonite with at least 20% calcium in exchange positions, when the external solution contains above 4 mM charge equivalents. This result is in agreement with the presented conceptual view of sol formation and measured equilibrium properties in mixed calcium/sodium montmorillonite. The findings imply that the buffer will be stable for non-glacial conditions. However, erosion due to sol formation cannot be ruled out for glacial conditions.

  7. Dune erosion above revetments

    NARCIS (Netherlands)

    Van Thiel de Vries, J.S.M.

    2012-01-01

    In a situation with a narrow dune, the dune base can be protected with a revetment to reduce dune erosion during extreme events. To quantify the effects of a revetment on storm impact, the functionality of the numerical storm impact model XBeach (Roelvink et al., 2009) is extended to account for the

  8. The effect of abrasive particle size on the wear behaviour of metal matrix composites

    International Nuclear Information System (INIS)

    Sahin, Y.; Ozdin, K.

    2004-01-01

    The effect of abrasive particle size on the wear behavior of the SiC particle-reinforced aluminium composites produced by liquid metallurgy was investigated under different sizes of SiC grits at a fixed speed. The results show that the wear loss of composite was considerably lower than that of aluminium alloy. The wear loss increased linearly with sliding distance for both materials, but indicating a considerable difference. It increased with increasing SiC abrasive particles. Moreover, SEM examination indicates that abrasive wear observed for the matrix alloy. The depth of wear grooves decreased with decreasing the abrasive particle size and load. For the composites, wear surfaces were found to be a quite smooth indicating that no abrasive grooves appeared

  9. Categorization of erosion control matting.

    Science.gov (United States)

    2012-05-29

    Erosion control is a critical aspect of any Georgia Department of Transportation (GDOT) : construction project, with the extreme negative impacts of high sediment loads in natural : waterways having been well documented. A variety of erosion control ...

  10. Respirator studies for the ERDA Division of Safety, Standards, and Compliance, July 1, 1975--June 30, 1976. [Physiological effects of wearing respirators

    Energy Technology Data Exchange (ETDEWEB)

    Davis, T.O.; Raven, P.B.; Shafer, C.L.; Linnebur, A.C.; Bustos, J.M.; Wheat, L.D.; Douglas, D.D.

    1977-03-01

    Results of a study to determine what effect wearing a respirator has on worker performance, and which physiological parameters an industrial physician should consider when examining an employee who will be wearing a respirator while working are presented. (TFD)

  11. Performance and wear characteristics of ceramic, cemented carbide, and metal nozzles used in coal-water-slurry boilers

    Energy Technology Data Exchange (ETDEWEB)

    Deng, J.X.; Ding, Z.L.; Zhou, H.M.; Tan, Y.Q. [Xiangtan University, Xiangtan (China). School of Mechanical Engineering

    2009-09-15

    Ceramics, cemented carbides, and metals were prepared to be used as nozzles in CWS boilers. CWS burning tests in a boiler with these nozzles were carried out. The erosion wear resistance of these nozzles was compared by determining their erosion rates and hole diameter variation. Results showed that the life of the ceramic nozzles is about 30 times high than that of the metal nozzles. The wear types at the nozzle wall surface differed in various positions. The nozzle center wall section suffers form abrasive impact under low impact angles, and the damage at the center wall mainly occurs by plowing and plastic deformation for metals, and by polishing action for carbides and ceramics. The primary wear mechanisms at the exit of ceramic nozzle exhibited thermal shock damage with chipping owing to the greater thermal stresses.

  12. Dental Erosion from an Excess of Vitamin C

    Directory of Open Access Journals (Sweden)

    Priya Bahal

    2014-01-01

    Full Text Available Acid erosion of enamel is the chemical dissolution of the superficial layers of teeth without the presence of bacteria. If the presence and exposure of a demineralising agent such as vitamin C is frequent and prolonged, it can lead to significant tooth wear. This case report discusses one such presentation and as a result of the occlusal relationship, this serves to effectively demonstrate the localised effects of vitamin C-induced acid erosion. The management of localised tooth wear with composite restorations utilising the Dahl principle to replace lost tooth tissue is also reported. Clinical Relevance. Patients should be made aware of the erosive nature of chewable vitamin C tablets and their potentially harmful effects on the dentition if consumed in excess. Objective Statement. The reader should understand the clinical implications of an excessive intake of vitamin C. This demonstrates the importance of the manufacturer’s instructions and the clinician’s role in advising patients with regard to the correct therapeutic doses.

  13. Three-dimensional in vitro measurements of tooth wear using fluoridated dentifrices.

    Science.gov (United States)

    Al-Mashhadani, A; Plygkos, I; Bozec, L; Rodriguez, J M

    2016-09-01

    The aim of this study was to compare differences in wear of human enamel and dentine in vitro using a 3D measurement method comparing silica versus non-silica containing fluoridated dentifrices (Colgate Total(™) [CT] or Fluor Protector Gel(™) [FPG]). Mounted native enamel (n = 36) and polished dentine (n = 36) samples were subjected to 10 wear cycles. Each cycle consisted of: (1) 1 hour remineralization in artificial saliva (AS); (2) 10 minute erosion (0.3% citric acid; pH = 2.8); (3) 2 minute toothbrush abrasion in AS (G1, control) or a slurry of 3:1 by weight of AS:dentifrice (G2 = CT; G3 = FPG) under a load of 2 N. Each group contained 12 enamel and 12 dentine samples. Paired pre- and post-wear scans made with a contacting scanner were digitally superimposed using ball bearings as datum. Mean and (SD) enamel wear was G1 = 21.9 μm (6.4); G2 = 15.2 μm (2.8); G3 = 16.9 μm (3.2). Enamel wear was not different between dentifrices (p = 0.99). Both dentifrices resulted in less enamel wear compared to the control (p Dental Association.

  14. Soil erosion and agricultural sustainability

    OpenAIRE

    Montgomery, David R.

    2007-01-01

    Data drawn from a global compilation of studies quantitatively confirm the long-articulated contention that erosion rates from conventionally plowed agricultural fields average 1–2 orders of magnitude greater than rates of soil production, erosion under native vegetation, and long-term geological erosion. The general equivalence of the latter indicates that, considered globally, hillslope soil production and erosion evolve to balance geologic and climate forcing, whereas conventional plow-bas...

  15. Research on the effect of wear-ring clearances to the performance of centrifugal pump

    International Nuclear Information System (INIS)

    Zhao, W G; Li, Y B; Wang, X Y; Sun, J P; Wu, G X

    2012-01-01

    In order to study the effect of wear-ring clearance on the performance of centrifugal pump, based on the Reynolds Time-Averaged N-S equations and RNG k-ε turbulence model, a centrifugal pump was simulated with three variable styles of the wear-rings: Only the clearance of the front wear-ring was changed, only the clearance of the back wear-ring was changed and both were changed. Numerical results agree well with the experimental results. In the three changing styles of the clearance, the variable of the clearance of front wear-ring has the most influence on the performance of centrifugal pump. The existence of wear-ring not only has an effect on the volumetric loss of the centrifugal pump, but also on the performance of the centrifugal pump. Relative to the experimental studies, numerical simulation methods have some advantages, such as low cost, fast and efficient, and easy to get the detailed structure of the internal flow characteristics, so it has been widely used in the fluid machinery study. In order to study the effect of wear-ring clearance on the performance of centrifugal pump, based on the Reynolds Time-Averaged N-S equations and RNG k-ε turbulence model, a centrifugal pump was simulated with three variable styles of the wear-rings: Only the clearance of the front wear-ring was changed, only the clearance of the back wear-ring was changed and both were changed. Numerical results agree well with the experimental results. In the three changing styles of the clearance, the variable of the clearance of front wear-ring has the most influence on the performance of centrifugal pump.

  16. Dry Sliding Wear Behavior of Super Duplex Stainless Steel AISI 2507: a Statistical Approach

    Directory of Open Access Journals (Sweden)

    Davanageri M.

    2016-12-01

    Full Text Available The dry sliding wear behavior of heat-treated super duplex stainless steel AISI 2507 was examined by taking pin-on-disc type of wear-test rig. Independent parameters, namely applied load, sliding distance, and sliding speed, influence mainly the wear rate of super duplex stainless steel. The said material was heat treated to a temperature of 850°C for 1 hour followed by water quenching. The heat treatment was carried out to precipitate the secondary sigma phase formation. Experiments were conducted to study the influence of independent parameters set at three factor levels using the L27 orthogonal array of the Taguchi experimental design on the wear rate. Statistical significance of both individual and combined factor effects was determined for specific wear rate. Surface plots were drawn to explain the behavior of independent variables on the measured wear rate. Statistically, the models were validated using the analysis of variance test. Multiple non-linear regression equations were derived for wear rate expressed as non-linear functions of independent variables. Further, the prediction accuracy of the developed regression equation was tested with the actual experiments. The independent parameters responsible for the desired minimum wear rate were determined by using the desirability function approach. The worn-out surface characteristics obtained for the minimum wear rate was examined using the scanning electron microscope. The desired smooth surface was obtained for the determined optimal condition by desirability function approach.

  17. The relationship between tooth wear in the primary and permanent dentitions.

    Science.gov (United States)

    Sales-Peres, S H C; Sales-Peres, A C; Marsicano, J A; Carvalho, C A P; Carvalho, F S; Lauris, J R P; Sales-Peres, A

    2011-09-01

    To evaluate the relationship between tooth wear in primary and permanent dentition in 7 to 10-year-old school children, in 2007. An epidemiological cross-sectional survey was conducted by trained, calibrated examiners, using the dental wear index (DWI). The cluster sample consisted of 764 children (382 boys, 382 girls) attending 4 public schools selected in different regions of the city. The DWI was proposed to evaluate primary and permanent teeth, coded as letters and numbers, respectively. Data were collected via clinical examinations performed outdoors under natural light, following the WHO recommendations and using a dental mirror and probe. Proportions and confidence intervals were used to describe the prevalence of dental wear. The Mann-Whitney and the Odds Ratio (OR) tests were used to compare the tooth wear prevalence between primary and permanent teeth according to surface (p tooth wear. The tooth wear was mostly seen on the occlusal/incisal surfaces (47%), involving enamel or enamel-dentine. Tooth wear in primary teeth was found in canines and molars (93%) and in permanent teeth in molars (34%). There was significant difference between primary and permanent teeth (p primary teeth was greater in boys than in girls (p = 0.02) but not in permanent teeth. The results suggest that 7 to 10-year-old children with tooth wear in primary teeth had more chances of developing tooth wear in permanent dentition. However, the findings of this study are not conclusive as the associations described are not causal.

  18. Should School Nurses Wear Uniforms?

    Science.gov (United States)

    Journal of School Health, 2001

    2001-01-01

    This 1958 paper questions whether school nurses should wear uniforms (specifically, white uniforms). It concludes that white uniforms are often associated with the treatment of ill people, and since many people have a fear reaction to them, they are not necessary and are even undesirable. Since school nurses are school staff members, they should…

  19. Wear performance of laser processed tantalum coatings

    Energy Technology Data Exchange (ETDEWEB)

    Dittrick, Stanley; Balla, Vamsi Krishna; Bose, Susmita; Bandyopadhyay, Amit, E-mail: amitband@wsu.edu

    2011-12-01

    This first generation investigation evaluates the in vitro tribological performance of laser-processed Ta coatings on Ti for load-bearing implant applications. Linear reciprocating wear tests in simulated body fluid showed one order of magnitude less wear rate, of the order of 10{sup -4} mm{sup 3}(N.m){sup -1}, for Ta coatings compared to Ti. Our results demonstrate that Ta coatings can potentially minimize the early-stage bone-implant interface micro-motion induced wear debris generation due to their excellent bioactivity comparable to that of hydroxyapatite (HA), high wear resistance and toughness compared to popular HA coatings. Highlights: {yields} In vitro wear performance of laser processed Ta coatings on Ti was evaluated. {yields} Wear tests in SBF showed one order of magnitude less wear for Ta coatings than Ti. {yields} Ta coatings can minimize early-stage micro-motion induced wear debris generation.

  20. Friction and wear behaviour of ceramic-hardened steel couples under reciprocating sliding motion

    NARCIS (Netherlands)

    He, Y.; Winnubst, Aloysius J.A.; Schipper, Dirk J.; Bakker, P.M.V.; Bakker, P.M.V.; Burggraaf, Anthonie; Burggraaf, A.J.; Verweij, H.

    1995-01-01

    The friction and wear behaviour of ZrO2-Y203, ZrO2-Y203-CeO2 and ZrO2-A1203 composite ceramics against hardened steel AISI-52100 were investigated using a pin on plate configuration under reciprocating motion. The reproducibility of the results was examined in this configuration. Wear

  1. Complications Caused by Contact Lens Wearing

    OpenAIRE

    Beljan, Jasna; Beljan, Kristina; Beljan, Zdravko

    2013-01-01

    Complications in wearing contact lenses are very rare and caused by poor maintenance, over-extended wear and wearing of contact lenses in a polluted environment. Regular control by a professional person can efficiently reduce the number of complications. This paper describes the most common risks factors for complications, and complications of wearing contact lenses with the classification according to the anatomic parts of the eye: eyelids, tear film, limbus, corneal epithelium, corneal stro...

  2. INVESTIGATION OF ANGULAR BALL BEARING WEAR

    Directory of Open Access Journals (Sweden)

    A. L. Savchenko

    2006-01-01

    Full Text Available Wearing process of balls in an angular ball bearing has been investigated in the paper. Force affecting a separator from the side of balls is determined theoretically. Wear rate may be calculated with a formula for abrasive wear while substituting numerical parameter values of the investigated ball bearing for formula symbols.

  3. Needs and challenges in precision wear measurement

    Energy Technology Data Exchange (ETDEWEB)

    Blau, P.J.

    1996-01-10

    Accurate, precise wear measurements are a key element in solving both current wear problems and in basic wear research. Applications range from assessing durability of micro-scale components to accurate screening of surface treatments and thin solid films. Need to distinguish small differences in wear tate presents formidable problems to those who are developing new materials and surface treatments. Methods for measuring wear in ASTM standard test methods are discussed. Errors in using alterate methods of wear measurement on the same test specimen are also described. Human judgemental factors are a concern in common methods for wear measurement, and an experiment involving measurement of a wear scar by ten different people is described. Precision in wear measurement is limited both by the capabilities of the measuring instruments and by the nonuniformity of the wear process. A method of measuring wear using nano-scale indentations is discussed. Current and future prospects for incorporating advanced, higher-precision wear measurement methods into standards are considered.

  4. Consideration of Wear Rates at High Velocities

    Science.gov (United States)

    2010-03-01

    tionally, the texts by Bayer [3; 4], Rabinowicz [30], and Stachowiak [32] thoroughly cover the topic of wear mechanisms. A summary of the material is...Metals at High Sliding Speeds,” Wear, 44(1):109–125, August 1977. 32. Stachowiak , G. W. Wear - Materials, Mechanisms and Practice. Tribology in

  5. Seismicity, seismology and erosion

    Science.gov (United States)

    Hovius, Niels; Meunier, Patrick; Burtin, Arnaud; Marc, Odin

    2013-04-01

    At the interface of geomorphology and seismology, patterns of erosion can be used to constrain seismic processes, and seismological instruments to determine geomorphic activity. For example, earthquakes trigger mass wasting in proportion to peak ground velocity or acceleration, modulated by local geologic and topographic conditions. This geomorphic response determines the mass balance and net topographic effect of earthquakes. It can also be used to obtain information about the distribution of seismic slip where instrumental observations are not available. Equally, seismometers can register the signals of geomorphic processes, revealing their location, type and magnitude. The high temporal resolution of such records can help determine the exact meteorological conditions that gave rise to erosion events, and the interactions between individual surface processes during such events. We will illustrate this synergy of disciplines with examples from active mountain belts around the world, including Taiwan, Japan, Papua New Guinea and the Alps.

  6. Abrasive wear on eroded root dentine after different periods of exposure to saliva in situ.

    Science.gov (United States)

    Hara, Anderson Takeo; Turssi, Cecilia Pedroso; Teixeira, Erica Capelletto Nogueira; Serra, Mônica Campos; Cury, Jaime Aparecido

    2003-10-01

    The effect of salivary exposure time on the abrasive wear of acid-eroded dentine was evaluated in situ. One-hundred and twenty bovine root dentine slabs were randomly assigned into six groups (A-F) and placed in intraoral palatal devices, which were worn by 10 volunteers for 4 d. On the first day, no erosive/abrasive procedures were carried out. On the following 3 d, erosive challenges were performed extraorally, two times per day, by immersing the device for 90 s in a soft drink. Subsequently, the group A specimens were immediately brushed (40 strokes), and the others were brushed after the following times: B, 20 min; C, 40 min; and D, 60 min. Group E specimens were only acid-eroded and those of group F were only brushed. Dentine wear was measured with a profilometer. anova and Dunnett's test showed that groups A-D did not differ statistically from the control group E but differed from the control group F. The lowest mean value was found for group F. Regression analysis was unable to show salivary effect on dentine wear reduction. The data suggest that the exposure time of saliva of up to 60 min has no effect on reducing the eroded dentine wear by toothbrushing.

  7. Formation of nano-laminated structures in a dry sliding wear-induced layer under different wear mechanisms of 20CrNi2Mo steel

    Science.gov (United States)

    Yin, Cun-hong; Liang, Yi-long; Jiang, Yun; Yang, Ming; Long, Shao-lei

    2017-11-01

    The microstructures of 20CrNi2Mo steel underneath the contact surface were examined after dry sliding. Scanning Electronic Microscopy (SEM), Transmission Electron Microscopy (TEM), Electron Backscattered Diffraction (EBSD) and an ultra-micro-hardness tester were used to characterize the worn surface and dry sliding wear-induced layer. Martensite laths were ultra-refined due to cumulative strains and a large strain gradient that occurred during cyclic loading in wear near the surface. The microstructure evolution in dominant abrasive wear differs from that in adhesive wear. In dominant abrasive wear, only bent martensite laths with high-density deformation dislocations were observed. In contrast, in dominant adhesive wear, gradient structures were formed along the depth from the wear surface. Cross-sectional TEM foils were prepared in a focused ion beam (FIB) to observe the gradient structures in a dry sliding wear-induced layer at depths of approximately 1-5 μm and 5-20 μm. The gradient structures contained nano-laminated structures with an average thickness of 30-50 nm and bent martensite laths. We found that the original martensite laths coordinated with the strain energy and provided origin boundaries for the formation of gradient structures. Geometrically necessary boundaries (GNBs) and isolated dislocation boundaries (IDBs) play important roles in forming the nano-laminated structures.

  8. Rainfall erosivity map for Ghana

    International Nuclear Information System (INIS)

    Oduro Afriyie, K.

    1995-10-01

    Monthly rainfall data, spanning over a period of more than thirty years, were used to compute rainfall erosivity indices for various stations in Ghana, using the Fournier index, c, defined as p 2 /P, where p is the rainfall amount in the wettest month and P is the annual rainfall amount. Values of the rainfall erosivity indices ranged from 24.5 mm at Sunyani in the mid-portion of Ghana to 180.9 mm at Axim in the south western coastal portion. The indices were used to construct a rainfall erosivity map for the country. The map revealed that Ghana may be broadly divided into five major erosion risk zones. The middle sector of Ghana is generally in the low erosion risk zone; the northern sector is in the moderate to severe erosion risk zone, while the coastal sector is in the severe to extreme severe erosion risk zone. (author). 11 refs, 1 fig., 1 tab

  9. Agave Chewing and Dental Wear: Evidence from Quids.

    Science.gov (United States)

    Hammerl, Emily E; Baier, Melissa A; Reinhard, Karl J

    2015-01-01

    Agave quid chewing is examined as a potential contributing behavior to hunter-gatherer dental wear. It has previously been hypothesized that the contribution of Agave quid chewing to dental wear would be observed in communities wherever phytolith-rich desert succulents were part of subsistence. Previous analysis of coprolites from a prehistoric agricultural site, La Cueva de los Muertos Chiquitos in Durango, Mexico, showed that Agave was a consistent part of a diverse diet. Therefore, quids recovered at this site ought to be useful materials to test the hypothesis that dental wear was related to desert succulent consumption. The quids recovered from the site were found to be largely derived from chewing Agave. In this study, the quids were found to be especially rich in phytoliths, and analysis of dental casts made from impressions left in the quids revealed flat wear and dental attrition similar to that of Agave-reliant hunter-gatherers. Based on evidence obtained from the analysis of quids, taken in combination with results from previous studies, it is determined that Agave quid chewing was a likely contributing factor to dental wear in this population. As such, our method provides an additional avenue of dental research in areas where quids are present.

  10. Agave Chewing and Dental Wear: Evidence from Quids.

    Directory of Open Access Journals (Sweden)

    Emily E Hammerl

    Full Text Available Agave quid chewing is examined as a potential contributing behavior to hunter-gatherer dental wear. It has previously been hypothesized that the contribution of Agave quid chewing to dental wear would be observed in communities wherever phytolith-rich desert succulents were part of subsistence. Previous analysis of coprolites from a prehistoric agricultural site, La Cueva de los Muertos Chiquitos in Durango, Mexico, showed that Agave was a consistent part of a diverse diet. Therefore, quids recovered at this site ought to be useful materials to test the hypothesis that dental wear was related to desert succulent consumption. The quids recovered from the site were found to be largely derived from chewing Agave. In this study, the quids were found to be especially rich in phytoliths, and analysis of dental casts made from impressions left in the quids revealed flat wear and dental attrition similar to that of Agave-reliant hunter-gatherers. Based on evidence obtained from the analysis of quids, taken in combination with results from previous studies, it is determined that Agave quid chewing was a likely contributing factor to dental wear in this population. As such, our method provides an additional avenue of dental research in areas where quids are present.

  11. Actinides, accelerators and erosion

    Directory of Open Access Journals (Sweden)

    Fifield L.K.

    2012-10-01

    Full Text Available Fallout isotopes can be used as artificial tracers of soil erosion and sediment accumulation. The most commonly used isotope to date has been 137Cs. Concentrations of 137Cs are, however, significantly lower in the Southern Hemisphere, and furthermore have now declined to 35% of original values due to radioactive decay. As a consequence the future utility of 137Cs is limited in Australia, with many erosion applications becoming untenable within the next 20 years, and there is a need to replace it with another tracer. Plutonium could fill this role, and has the advantages that there were six times as many atoms of Pu as of 137Cs in fallout, and any loss to decay has been negligible due to the long half-lives of the plutonium isotopes. Uranium-236 is another long-lived fallout isotope with significant potential for exploitation as a tracer of soil and sediment movement. Uranium is expected to be more mobile in soils than plutonium (or caesium, and hence the 236U/Pu ratio will vary with soil depth, and so could provide an independent measure of the amount of soil loss. In this paper we discuss accelerator based ultra-sensitive measurements of plutonium and 236U isotopes and their advantages over 137Cs as tracers of soil erosion and sediment movement.

  12. Wear Resistance of Austempered Ductile Iron with Nanosized Additives

    Science.gov (United States)

    Kaleicheva, J. K.; Mishev, V.

    2018-01-01

    The wear resistance, microstructure and mechanical properties of austempered ductile iron (ADI) with nanosized additives of cubic boron nitride cBN are investigated. Samples of ductile iron are put under austhempering at the following conditions: heating at 900°С, 1 h and isothermal retention at 280оС, 2 h and 380°С, 2 h with the aim to achieve a lower bainitic structure and an upper bainitic structure. The experimental wear testing of austempered ductile irons is performed in friction conditions of a fixed abrasive by a cinematic scheme „pin - disc” using an accelerated testing method and device. The microstructure of the ADI is investigated by metallographic and X-Ray analyses. The Vickers hardness testing and impact strength examination are carried out. The influence of the nanosized additives of cBN on the wear resistance, microstructure, impact strength and hardness of the ADI is investigated.

  13. Dental wear quantity and direction in Chalcolithic and Medieval populations from southwest France.

    Science.gov (United States)

    Grimoud, Anne-Marie; Gibbon, Victoria E

    2017-01-01

    The aim of this study was to verify if dental wear changed due to the dietary shift between the Chalcolithic and Middle Ages from relatively hard and fibrous foods to soft cooked cereals. This was accomplished by comparing dental wear quantity and direction between people from two archaeological sites, Les Treilles during the Chalcolithic (mixed subsistence farmers) and Marsan from the Middle Ages (agriculturalists) in southwest France. The materials studied include 65 mandibles, 32 from Les Treilles and 33 from Marsan; 549 teeth were studied. The results show statistically significant difference in wear quantity and direction, the Chalcolithic population (Les Treilles) had the greatest levels of wear in a mainly oblique direction, with the anterior teeth heavily affected by wear. Comparatively, the Medieval sample (Marsan) had lesser levels of wear in a mainly horizontal direction, and the most heavily worn teeth were the molars and incisors. The quantity of wear seems to correlate well with changes in diet, the high level of wear on the anterior teeth in the Chalcolithic sample corresponds with the consumption of a mixed diet of fibrous and tough foods. At Marsan, the lower wear quantity was likely due to a diet of soft boiled cereals, requiring less mastication. However, wear direction appears dependent on several factors and may correlate with more mixed subsistence practices. This study demonstrates the need for additional research into the complex actions of mastication and its effect on dental wear, as well as standardised methodology for the examination of dental wear in archaeological samples. Copyright © 2016 Elsevier GmbH. All rights reserved.

  14. The microstructural dependence of wear resistance in austenite containing plate steels

    Science.gov (United States)

    Wolfram, Preston Charles

    The purpose of this project was to examine the microstructural dependence of wear resistance of various plate steels, with interests in exploring the influence of retained austenite (RA). Materials resistant to abrasive wear are desirable in the industrial areas of agriculture, earth moving, excavation, mining, mineral processing, and transportation. Abrasive wear contributes to significant financial cost associated with wear to the industry. The motivation for the current study was to determine whether it would be beneficial from a wear resistance perspective to produce plate steels with increased amounts of retained austenite. This thesis investigates this motivation through a material matrix containing AR400F, Abrasive (0.21 wt pct C, 1.26 wt pct Mn, 0.21 wt pct Si, 0.15 wt pct Ni, 0.18 wt pct Mo), Armor (0.46 wt pct C, 0.54 wt pct Mn, 0.36 wt pct Si, 1.74 wt pct Ni, 0.31 wt pct Mo), 9260, 301SS, Hadfield, and SAE 4325 steels. The Abrasive, Armor and 9260 steels were heat treated using different methods such as quench and temper, isothermal bainitic hold, and quench and partitioning (Q&P). These heat treatments yielded various microstructures and the test matrix allowed for investigation of steels with similar hardness and varying levels of RA. The wear test methods used consisted of dry sand rubber wheel (DSRW), impeller-tumbler impact-abrasion (impeller), and Bond abrasion wear testing. DSRW and impeller wear resistance was found to increase with hardness and retained austenite levels at certain hardness levels. Some Q&P samples exhibited similar or less wear than the Hadfield steels in DSRW and impeller tests. Scanning electron microscopy investigation of wear surfaces revealed different wear mechanisms for the different wear test methods ranging from micro-plowing, to micro-cutting and to fragmentation.

  15. Wear Distribution Detection of Knee Joint Prostheses by Means of 3D Optical Scanners

    Directory of Open Access Journals (Sweden)

    Saverio Affatato

    2017-03-01

    Full Text Available The objective of this study was to examine total knee polyethylene inserts from in vitro simulation to evaluate and display—using a 3D optical scanner—wear patterns and wear rates of inserts exposed to wear by means of simulators. Various sets of tibial inserts have been reconstructed by using optical scanners. With this in mind, the wear behavior of fixed and mobile bearing polyethylene knee configurations was investigated using a knee wear joint simulator. After the completion of the wear test, the polyethylene menisci were analyzed by an innovative 3D optical scanners in order to evaluate the 3D wear distribution on the prosthesis surface. This study implemented a new procedure for evaluating polyethylene bearings of joint prostheses obtained after in vitro wear tests and the proposed new approach allowed quantification of the contact zone on the geometry of total knee prostheses. The results of the present study showed that mobile TKPs (total knee prosthesis have lower wear resistance with respect to fixed TKPs.

  16. Scoping erosion flow loop test results in support of Hanford WTP

    International Nuclear Information System (INIS)

    Duignan, M.; Imrich, K.; Fowley, M.; Restivo, M.; Reigel, M.

    2015-01-01

    The Waste Treatment and Immobilization Plant (WTP) will process Hanford Site tank waste by converting the waste into a stable glass form. Before the tank waste can be vitrified, the baseline plan is to process the waste through the Pretreatment (PT) Facility where it will be mixed in various process vessels using Pulse Jet Mixers (PJM) and transferred to the High Level Waste (HLW) or Low Activity Waste (LAW) vitrification facilities. The Department of Energy (DOE) and Defense Nuclear Facility Safety Board (DNFSB), as well as independent review groups, have raised concerns regarding the design basis for piping erosion in the PT Facility. Due to the complex nature of slurry erosion/corrosion wear and the unique conditions that exist within the PT Facility, additional testing has been recommended by these entities. Pipe loop testing is necessary to analyze the potential for localized wear at elbows and bends, close the outstanding PT and HLW erosion/corrosion technical issues, and underpin BNI's design basis for a 40-year operational life for black cell piping and vessels. SRNL is consulting with the DOE Office of River Protection (ORP) to resolve technical concerns related to piping erosion/corrosion (wear) design basis for PT. SRNL was tasked by ORP to start designing, building, and testing a flow loop to obtain long-term total-wear rate data using bounding simulant chemistry, operating conditions, and prototypical materials. The initial test involved a scoping paint loop to locate experimentally the potential high-wear locations. This information will provide a basis for the placement of the many sensitive wear measurement instruments in the appropriate locations so that the principal flow-loop test has the best chance to estimate long-term erosion and corrosion. It is important to note that the scoping paint loop test only utilized a bounding erosion simulant for this test. A full chemical simulant needs to be added for the complete test flow loop. The

  17. Effect of Manganese Additions and Wear Parameter on the Tribological Behaviour of NFGrey (8 Cast Iron

    Directory of Open Access Journals (Sweden)

    S. Olatunji

    2012-12-01

    Full Text Available The effect of manganese and wear parameter on the abrasive wear behaviour of NFGREY8 cast iron composition under dry lubrication conditions was investigated. The wear parameters studied are sliding speed, applied load, time and percentage of ferro-manganese additions. The experimental data were taken in a controlled way. Scanning electron microscope was used to examine the morphology of the samples. The results from linear regression equation and analysis of variances (ANOVA shows that manganese additions, load and speed variable are more pronounced on the wear behaviour of the NFGrey (8 cast iron. The result showed that the additions of the 75 % ferro manganese grade decreases the carbon equivalent CE and fortify the matrix with the formation of tough (FeMn3C inter-metallic leading to increased wear resistance of the examined composition.

  18. Friction and wear in sodium

    International Nuclear Information System (INIS)

    Hoffman, N.J.; Droher, J.J.

    1973-01-01

    In the design of a safe and reliable sodium-cooled reactor one of the more important problem areas is that of friction and wear of components immersed in liquid sodium or exposed to sodium vapor. Sodium coolant at elevated temperatures may severely affect most oxide-bearing surface layers which provide corrosion resistance and, to some extent, lubrication and surface hardness. Consequently, accelerated deterioration may be experienced on engaged-motion contact surfaces, which could result in unexpected reactor shutdown from component malfunction or failure due to galling and seizure. An overall view of the friction and wear phenomena encountered during oscillatory rubbing of surfaces in high-temperature, liquid-sodium environments is presented. Specific data generated at the Liquid Metal Engineering Center (LMEC) on this subject is also presented. (U.S.)

  19. Erosion Characteristics of Nanoparticle-Reinforced Polyurethane Coatings on Stainless Steel Substrate

    Science.gov (United States)

    Syamsundar, C.; Chatterjee, Dhiman; Kamaraj, M.; Maiti, A. K.

    2015-04-01

    Hydropower generation from the Himalayan rivers in India faces challenge in the form of silt-laden water which can erode the turbine blades and reduce turbine life. To address this issue, polyurethane coatings reinforced with boron carbide (B4C) or silicon carbide (SiC) nanoparticles on 16Cr-5Ni martensitic stainless steel substrate were used in the present investigation to improve erosion wear resistance in silt erosion conditions. Slurry erosive wear tests were carried out based on ASTM G-73 protocol at various test conditions of impact velocity, impingement angle, and erodent particle size as well as slurry concentrations as determined by the implementation of Taguchi design of experiments. Analysis of variance studies of erosion rate indicated that nanoparticle content in PU material is the single most important parameter, and interaction of impact velocity and impingement angle was also proved to be significant. The coatings with B4C nanoparticles had higher wear resistances than those with SiC nanoparticles due to higher hardness of the former. An interesting finding from the results is that there is an optimum amount of nanoparticles at which mass removal is the minimum. This observation has been explained in terms of surface characteristics of coatings as brought out by a combination of measurements including SEM images as well as roughness measurement.

  20. Slurry Erosion and Corrosion Behavior of Some Engineering Polymers Applied by Low-Pressure Flame Spray

    Science.gov (United States)

    Lima, Carlos Roberto Camello; Mojena, Miguel Angel Reyes; Rovere, Carlos Alberto Della; de Souza, Natalia Ferraresso Cardoso; Fals, Hipolito Domingo Carvajal

    2016-11-01

    The erosive wear and corrosion resistance of three types of flame spray-deposited polymer coatings was analyzed. The erosive wear test was performed in slurry pot tester with rotational movement using distilled water and mix quartz particles (300 g/l). Two impact angles of the particles were used, reaching 4.15 m/s average impact velocity. Corrosion resistance of the polymer coatings and degradation behavior were investigated by electrochemical impedance spectroscopy in a solution of 0.5 M sodium chloride at room temperature for a total immersion time of 1 year. The interpretation of the results was made according to the Bode plot. It is proven a better slurry erosion wear performance for PEEK and PA12 coatings when the particles impact at 90° angle. For impact angle of 30°, there is no significant difference in the erosion performance of PEEK, PEI, and PA12 coatings. No major changes occurred in the impedance module for PA12 and PEEK samples, indicating that these coatings can protect the steel substrate for extended periods of time. The lower PEI performance is believed to be related to the improper choice of spraying parameters, as the spray conditions were kept constant for the three feedstock materials.

  1. Wear resistance of hydrophobic surfaces

    Science.gov (United States)

    Martinez, MA; Abenojar, J.; Pantoja, M.; López de Armentia, S.

    2017-05-01

    Nature has been an inspiration source to develop artificial hydrophobic surfaces. During the latest years the development of hydrophobic surfaces has been widely researched due to their numerous ranges of industrial applications. Industrially the use of hydrophobic surfaces is being highly demanded. This is why many companies develop hydrophobic products to repel water, in order to be used as coatings. Moreover, these coating should have the appropriated mechanical properties and wear resistance. In this work wear study of a hydrophobic coating on glass is carried out. Hydrophobic product used was Sika Crystal Dry by Sika S.A.U. (Alcobendas, Spain). This product is currently used on car windshield. To calculate wear resistance, pin-on-disk tests were carried out in dry and water conditions. The test parameters were rate, load and sliding distance, which were fixed to 60 rpm, 5 N and 1000 m respectively. A chamois was used as pin. It allows to simulate a real use. The friction coefficient and loss weight were compared to determinate coating resistance

  2. Wear of dragline wire ropes

    Energy Technology Data Exchange (ETDEWEB)

    Dayawansa, D.; Kuruppu, M.; Mashiri, F.; Bartosiewicz, H. [Monash University (Caulfield Campus), Caulfield East, Vic. (Australia). Department of Mechanical Engineering,

    2005-07-01

    Wire ropes are one of the most heavily used components in a dragline. Hoist ropes are subjected to fatigue due to the cyclic nature of load handling as well as due to rope bending over the sheaves and the drum under load. This leads to wire breaks due to fatigue. Accumulation of a number of wire breaks close to each other can have a detrimental effect on the rope. Furthermore, to allow for the increasing demand for higher load capacity coupled with the inconvenience of having very large ropes, the factor of safety is often compromised, which increases the wear rate. Drag ropes are also subjected to heavy loads. More importantly, they are allowed to drag along the rough mine surface subjecting them to external physical abrasion. This makes the life of drag ropes one of the lowest among those used in a dragline. Suspension and IBS ropes are relatively uniformly loaded during their regular usage although they need to withstand dynamic load cycles as well as bending. Hence they tend to last for a number of years on average. The paper analyses the wear types and their severity of each of these rope applications, and suggests methods to determine rope wear rates and the resulting rope life. The paper further gives suggestions for good operating and maintenance practice that can extend the rope life and help reduce the large expenditure associated with every major rope change in a dragline. 6 refs., 8 figs., 1 tab.

  3. A Study of Cavitation Erosion

    International Nuclear Information System (INIS)

    Hiromu Isaka; Masatsugu Tsutsumi; Tadashi Shiraishi; Hiroyuki Kobayashi

    2002-01-01

    The authors performed experimental study for the purpose of the following two items from a viewpoint of cavitation erosion of a cylindrical orifice in view of a problem at the letdown orifice in PWR (Pressurized Water Reactor). 1. To get the critical cavitation parameter of the cylindrical orifice to establish the design criteria for prevention of cavitation erosion, and 2. to ascertain the erosion rate in such an eventuality that the cavitation erosion occurs with the orifice made of stainless steel with precipitation hardening (17-4-Cu hardening type stainless steel), so that we confirm the appropriateness of the design criteria. Regarding the 1. item, we carried out the cavitation tests to get the critical cavitation parameters inside and downstream of the orifice. The test results showed that the cavitation parameter at inception is independent of the length or the diameter of the orifice. Moreover, the design criteria of cavitation erosion of cylindrical orifices have been established. Regarding the 2. item, we tested the erosion rate under high-pressure conditions. The cavitation erosion actually occurred in the cylindrical orifice at the tests that was strongly resemble to the erosion occurred at the plant. It will be seldom to reproduce resemble cavitation erosion in a cylindrical orifice with the hard material used at plants. We could establish the criteria for preventing the cavitation erosion from the test results. (authors)

  4. Optimization of pulsed DC PACVD parameters: Toward reducing wear rate of the DLC films

    Energy Technology Data Exchange (ETDEWEB)

    Ebrahimi, Mansoureh [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, P.O. Box 1875-4413, Tehran (Iran, Islamic Republic of); Mahboubi, Farzad, E-mail: mahboubi@aut.ac.ir [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, P.O. Box 1875-4413, Tehran (Iran, Islamic Republic of); Naimi-Jamal, M. Reza [Research Laboratory of Green Organic Synthesis and Polymers, Department of Chemistry, Iran University of Science and Technology, P.O. Box 16846, Tehran (Iran, Islamic Republic of)

    2016-12-15

    Highlights: • Effect of pulsed DC PACVD deposition temperature, duty cycle, hydrogen flow and argon/CH4 flow ratio on the wear rate and durability of DLC films was studied. • Results show that wear rate of the DLC films, reduced from 14×E-4 mm3/Nm to 1×E-6 mm3/Nm with increasing the duty cycle from 50% to 80%. • In low duty cycle (around 50%), wear rate increases with increasing in Argon/CH4 flow ratio. • Oxidation, fatigue, abrasion and graphitization are main wear mechanisms in the DLC film. - Abstract: The effect of pulsed direct current (DC) plasma-assisted chemical vapor deposition (PACVD) parameters such as temperature, duty cycle, hydrogen flow, and argon/CH{sub 4} flow ratio on the wear behavior and wear durability of the diamond-like carbon (DLC) films was studied by using response surface methodology (RSM). DLC films were deposited on nitrocarburized AISI 4140 steel. Wear rate and wear durability of the DLC films were examined with the pin-on-disk method. Field emission scanning electron microscopy, Raman spectroscopy, and nanoindentation techniques were used for studying wear mechanisms, chemical structure, and hardness of the DLC films. RSM results show that duty cycle is one of the important parameters that affect the wear rate of the DLC samples. The wear rate of the samples deposited with a duty cycle of >75% decreases with an increase in the argon/CH4 ratio. In contrast, for a duty cycle of <65%, the wear rate increases with an increase in the argon/CH{sub 4} ratio. The wear durability of the DLC samples increases with an increase in the duty cycle, hydrogen flow, and argon/CH{sub 4} flow ratio at the deposition temperature between 85 °C and 110 °C. Oxidation, fatigue, abrasive wear, and graphitization are the wear mechanisms observed on the wear scar of the DLC samples deposited with the optimum deposition conditions.

  5. A terminological matter: paragenesis, antigravitative erosion or antigravitational erosion ?

    Directory of Open Access Journals (Sweden)

    Pasini G.

    2009-07-01

    Full Text Available In the speleological literature three terms are utilized to designate the “ascending erosion”: paragenesis (= paragénésis, coined in1968, antigravitative erosion (= erosione antigravitativa, coined in 1966 and antigravitational erosion (wrong English translation ofthe Italian term erosione antigravitativa, utilized later on. The term paragenesis should be abandoned because of the priority of theterm erosione antigravitativa - on the ground of the “law of priority” – and because of its ambiguous etimology. On the other hand,the term antigravitational erosion should be forsaken in favour of the term antigravitative erosion, given the meaning that the termsgravitation and gravity have in Physics. Therefore, to designate the phenomenon of the “ascending erosion” there would be nothingleft but the term antigravitative erosion.The antigravitative erosion process and its recognizability are illustrated.Examples of caves with evident antigravitative erosion phenomena, developed in different karstifiable rocks and in several partsof the world, are given.It is recalled that the antigravitative erosion is a phenomenon well-known since 1942 and widely proven and supported, and that it isrelatively easy – in many cases - to recognize the antigravitative origin of karstic passages.It is stressed that the antigravitative erosion is an important phenomenon, exclusive of the karstic caves and unique in nature.

  6. Eolian erosion of the Martian surface. I - Erosion rate similitude

    Science.gov (United States)

    Iversen, J. D.; White, B. R.; Greeley, R.; Pollack, J. B.

    1975-01-01

    A similitude parameter is derived which is based on theoretical considerations of erosion due to sand in saltation. This parameter has been used to correlate wind tunnel experiments of particle flow over model craters. The characteristics of the flow field in the vicinity and downstream of a crater are discussed and it is shown that erosion is initiated in areas lying under a pair of trailing vortices. The erosion rate parameter is used to calculate erosion rates on Mars, reported in Part 2, to be published later.

  7. Influence of toothbrushing on enamel softening and abrasive wear of eroded bovine enamel: an in situ study.

    Science.gov (United States)

    Rios, Daniela; Honório, Heitor Marques; Magalhães, Ana Carolina; Buzalaf, Marília Afonso Rabelo; Palma-Dibb, Regina Guenka; Machado, Maria Aparecida De Andrade Moreira; da Silva, Salete Moura Bonifácio

    2006-01-01

    This study assessed the surface softening and abrasive wear of eroded bovine enamel with or without the influence of toothbrushing. Five volunteers took part in this in situ study of 5 days. They wore acrylic palatal appliances containing 6 bovine enamel blocks divided in two rows with 3 blocks, which corresponded to the studied groups: erosion without toothbrushing (GI) and erosion with toothbrushing (GII). The blocks were subjected to erosion by immersion of the appliances in a cola drink for 10 minutes, 4 times a day. After that, no treatment was performed in one row (GI), whereas the other row was brushed (GII). The appliance was then replaced into the mouth. Enamel alterations were determined using profilometry and microhardness tests. Data were tested using paired Students t test (p wear values (microm) and percentage of superficial microhardness change (%SMHC) were respectively: GI--2.77 +/- 1.21/91.61 +/- 3.68 and GII--3.80 +/- 0.91/58.77 +/- 11.47. There was a significant difference in wear (p = 0.001) and %SMHC (p = 0.001) between the groups. It was concluded that the wear was more pronounced when associated to toothbrushing abrasion. However, toothbrushing promoted less %SMHC due to the removal of the altered superficial enamel layer.

  8. Destructive investigations of decommissioned guide tubes: characterization of wear

    International Nuclear Information System (INIS)

    Ambard, A.; Lina, A.; Bosselut, D.; Deforge, D.; Robinot, P.; Thebault, Y.; Paulhies, M.; Maingot, S.

    2011-01-01

    The wear of control rods has been a major maintenance concern for EDF since the nineties. Surface treatment of the rods (nitriding, chrome plating) were developed to deal with this issue. However, the question came to know whether the guiding tube in which those new control rods are inserted are also worn. EDF interest into guide tube wear has been renewed by the slow increase of the drop time in B06 position. EDF performed field examinations and some laboratory experiments to answer to this question. Two guide tubes were extracted from various cores. They were chosen due to their different positions within the core and the different nature of their counter bodies (different control rods surface treatment). Their continuous part were sliced to reduce their activity. Their dimensions were measured and compared to the nominal dimensions. Wear was evidenced with a low level. It is mainly concentrated around the notch. Some distinctions could be made depending on the guiding tube examined. Metallographic examinations were performed using SEM. The wear patterns of the guiding tubes appear similar from those of the control rods, which means that similar wear mechanisms must be involved. A tentative explanation of the increase of the rod drop time in position B06 is proposed. A tentative explanation of the low increase of rod drop time is presented. It could result from the conjunction of a larger pressing force in B06 position than in other position of the core as well as the conformal contact observed. The conformal contact in itself could results from the larger pressing force and the use of hardened rods. The findings of these field examinations have comforted EDF strategy concerning B06 guide tubes: they are changed before their drop time reaches a critical value. (authors)

  9. Associated factors of tooth wear among Malaysian 16-year-olds: a case-control study in Kota Bharu, Kelantan.

    Science.gov (United States)

    Saerah, N B; Mastura, N; bin Ismail, A R; Sadiq, M A

    2012-03-01

    To determine the associated factors of tooth wear (TW) among 16-year-old school children. A random selection of secondary school children from 8 government secondary schools in Kota Bharu, Kelantan, Malaysia, participated in this case-control study. The Smith and Knight Tooth Wear Index and WHO criteria were used to chart tooth wear and dental caries respectively. Saliva analyses used standards recommended by GC Asia Dental. Self-administered questionnaire provided socio-demographic profile of the family, general knowledge of tooth wear, oral hygiene, food and drinks practices and other associated variables for tooth wear. Analysis using multiple logistic regression was performed. Of the 576 children sampled, 40% of the 460 controls were male as were 57% of the 116 in the case group. Multivariate analysis showed gender, monthly household income, carbonated drinks, caries experience, pool swimming, duration of intake of orange juice and hydration rate and viscosity were significantly associated with wear. The factors associated with tooth wear were similar to those encountered in other studies. Oral health promotion activities should emphasise those factors which can be changed. The erosive potential of some foods and drinks require further investigation.

  10. The tooth wear evaluation system: a modular clinical guideline for the diagnosis and management planning of worn dentitions.

    Science.gov (United States)

    Wetselaar, P; Lobbezoo, F

    2016-01-01

    Tooth wear is a multifactorial condition, leading to the loss of dental hard tissues, viz. enamel and dentine. Tooth wear can be divided into the subtypes mechanical wear (attrition and abrasion) and chemical wear (erosion). Because of its multifactorial aetiology, tooth wear can manifest itself in many different representations, and therefore, it can be difficult to diagnose and manage the condition. A systematic approach is a sine qua non. In the below-described tooth wear evaluation system (TWES), all necessary tools for a clinical guideline are present in different modules. This allows the dental clinician, in a general practitioner setting as well as in a referral practice setting, to perform a state-of-the-art diagnostic process. To avoid the risk of a too cumbersome usage, the dental clinician can select only those modules that are appropriate for a given setting. The modules match with each other, which is indispensable and essential when different modules of the TWES are compared. With the TWES, it is possible to recognise the problem (qualifying), to grade its severity (quantifying), to diagnose the likely causes and to monitor (the progress of) the condition. In addition, a proposal for the classification of tooth wear is made. Further, it is possible to determine when to start a treatment, to make the decision which kind of treatment to apply and to estimate the level of difficulty of a restorative treatment. © 2015 John Wiley & Sons Ltd.

  11. Relationship Between Simulated Gap Wear and Generalized Wear of Resin Luting Cements.

    Science.gov (United States)

    Tsujimoto, A; Barkmeier, W W; Takamizawa, T; Latta, M A; Miayazaki, M

    The relationship between the simulated gap wear and generalized wear of resin luting cements was investigated. Five resin luting cements, G-Cem LinkForce (GL), Multilink Automix (MA), NX3 Nexus, Panavia V5 (PV), and RelyX Ultimate were evaluated and subsequently subjected to a wear challenge in a Leinfelder-Suzuki (Alabama) wear simulation device. Half of the specimens from each resin luting cement were photo-cured for 40 seconds and the other half were not photo-cured. The simulated gap and generalized wear were generated using a flat-ended stainless steel antagonist. Wear testing was performed in a water slurry of polymethyl methacrylate beads, and the simulated gap and generalized wear were determined using a noncontact profilometer (Proscan 2100) in conjunction with the Proscan and AnSur 3D software. A strong relationship was found between the gap wear and generalized wear simulation models. The simulated gap wear and generalized wear of the resin luting cements followed similar trends in terms of both volume loss and mean depth of wear facets with each curing method. Unlike the simulated gap wear and generalized wear of GL and PV, those of MA, NX, and RU were influenced by the curing method. The results of this study indicate that simulated gap wear of resin luting cements is very similar to simulated generalized wear. In most cases, dual curing appears to ensure greater wear resistance of resin luting cements than chemical curing alone. The wear resistance of some resin luting cements appears to be material dependent and is not influenced by the curing method.

  12. Wearing ambidextrous vinyl gloves does not impair manual dexterity.

    Science.gov (United States)

    Drabek, Tomas; Boucek, Charles D; Buffington, Charles W

    2013-01-01

    Universal precautions mandate that health care workers wear gloves to prevent the unintended spread of bloodborne pathogens. Gloves may affect manual dexterity, generally delaying task completion. Our previous study showed that wearing the wrong size latex surgical glove degraded manual dexterity. The use of non-sterile and non-latex gloves may limit certain risks and be more cost-effective. However, such gloves may produce different results. We hypothesized that ambidextrous vinyl examination gloves would degrade manual dexterity compared with bare hands. We studied 20 random subjects from a medical environment. Subjects performed a standard battery of Grooved Pegboard tasks while bare-handed, wearing ambidextrous non-sterile vinyl gloves that were their preferred size, a size too small, and a size too large. The order was randomized with a Latin Square design to minimize the effects of time, boredom, and fatigue on the subjects. Subjects were also invited to comment on the fit of different size gloves. Wearing vinyl gloves of both the preferred size and a size up or down failed to affect manual dexterity vs. bare hands on time to insert pegs, and pegs dropped during insertion or removal. In contrast, the time to remove pegs was reduced by wearing preferred size vinyl gloves compared with performing the task with bare hands (Pgloves that were too small caused significant hand discomfort. Vinyl gloves surprisingly do not degrade manual dexterity even when worn in ill-fitting sizes. Wearing a preferred size vinyl glove vs. bare hands may improve dexterity in selected tasks. Choosing a comfortable, large size seems the best strategy when the preferred size is unavailable. Thinner vinyl gloves may improve grip and may not degrade touch as much as latex surgical gloves and may thus represent a reasonable choice for selected tasks.

  13. Shoulder erosions in renal osteodystrophy

    International Nuclear Information System (INIS)

    Bonavita, J.A.; Dalinka, M.K.

    1980-01-01

    The radiographic manifestations of renal osteodystrophy may be articular as well as osseous. The latter are well recognized, i.e. subperiosteal and subchondral bony resorption. Recently attention has been directed to the occurrence of an erosive arthritis of the hands and wrists in hyperparathyroidism. The authors present six patients with humeral head erosions, all of whom were on chronic long-term hemodialysis. These intra-articular erosions occurred at the 'bare' area of the humeral head and thus represent an erosive arthritis and therefore can be distinguished from the usual sites of subchondral and subperiosteal bony resorption seen in hyperparathyroidism. (orig.) [de

  14. Multiperspective analysis of erosion tolerance

    Directory of Open Access Journals (Sweden)

    Sparovek Gerd

    2003-01-01

    Full Text Available Erosion tolerance is the most multidisciplinary field of soil erosion research. Scientists have shown lack in ability to adequately analyze the huge list of variables that influence soil loss tolerance definitions. For these the perspectives of erosion made by farmers, environmentalists, society and politicians have to be considered simultaneously. Partial and biased definitions of erosion tolerance may explain not only the polemic nature of the currently suggested values but also, in part, the nonadoption of the desired levels of erosion control. To move towards a solution, considerable changes would have to occur on how this topic is investigated, especially among scientists, who would have to change methods and strategies and extend the perspective of research out of the boundaries of the physical processes and the frontiers of the academy. A more effective integration and communication with the society and farmers, to learn about their perspective of erosion and a multidisciplinary approach, integrating soil, social, economic and environmental sciences are essential for improved erosion tolerance definitions. In the opinion of the authors, soil erosion research is not moving in this direction and a better understanding of erosion tolerance is not to be expected in the near future.

  15. Time series analysis of tool wear in sheet metal stamping using acoustic emission

    Science.gov (United States)

    Vignesh Shanbhag, V.; Pereira, P. Michael; Rolfe, F. Bernard; Arunachalam, N.

    2017-09-01

    Galling is an adhesive wear mode that often affects the lifespan of stamping tools. Since stamping tools represent significant economic cost, even a slight improvement in maintenance cost is of high importance for the stamping industry. In other manufacturing industries, online tool condition monitoring has been used to prevent tool wear-related failure. However, monitoring the acoustic emission signal from a stamping process is a non-trivial task since the acoustic emission signal is non-stationary and non-transient. There have been numerous studies examining acoustic emissions in sheet metal stamping. However, very few have focused in detail on how the signals change as wear on the tool surface progresses prior to failure. In this study, time domain analysis was applied to the acoustic emission signals to extract features related to tool wear. To understand the wear progression, accelerated stamping tests were performed using a semi-industrial stamping setup which can perform clamping, piercing, stamping in a single cycle. The time domain features related to stamping were computed for the acoustic emissions signal of each part. The sidewalls of the stamped parts were scanned using an optical profilometer to obtain profiles of the worn part, and they were qualitatively correlated to that of the acoustic emissions signal. Based on the wear behaviour, the wear data can be divided into three stages: - In the first stage, no wear is observed, in the second stage, adhesive wear is likely to occur, and in the third stage severe abrasive plus adhesive wear is likely to occur. Scanning electron microscopy showed the formation of lumps on the stamping tool, which represents galling behavior. Correlation between the time domain features of the acoustic emissions signal and the wear progression identified in this study lays the basis for tool diagnostics in stamping industry.

  16. Plasma erosion switch

    International Nuclear Information System (INIS)

    Mendel, C.W. Jr.; Goldstein, S.A.; Miller, P.A.

    1976-01-01

    The plasma erosion switch is a device capable of initially carrying high currents, and then of opening in nanoseconds to stand off high voltages. It depends upon the erosion of a plasma which initially fills the switch. The sheath between the plasma and the cathode behaves as a diode with a rapidly increasing A-K gap. Preliminary tests of the switch on the Proto I accelerator at Sandia will be described. In these tests, the switch consisted of a cylinder of highly ionized plasma four inches in diameter and one-inch thick surrounding a one-inch cathode. The switch shorted out prepulse voltages and allowed energy to be stored in the diode inductance outside the switch until the accelerator current reached 75 kA. The switch impedance then rose rapidly to approximately 100 ω in 5 nanoseconds, whereupon the accelerator current transferred to the cathode. Current rise rates of 3.10 13 A/sec were limited by cathode turn-on. Voltage rise rates of 10 15 V/sec were achieved. The elimination of prepulse and machine turn-on transients allowed A-K gaps of 2 mm to be used with 2.5 MV pulses, yielding average E fields of 12 MV/cm. Staged versions of the device are being built and should improve rise rates. The switch shows promise for use with future, higher power, lower inductance machines

  17. Erosion in extruder flow

    Science.gov (United States)

    Kaufman, Miron; Fodor, Petru S.

    A detailed analysis of the fluid flow in Tadmor's unwound channel model of the single screw extruder is performed by combining numerical and analytical methods. Using the analytical solution for the longitudinal velocity field (in the limit of zero Reynolds number) allows us to devote all the computational resources solely for a detailed numerical solution of the transversal velocity field. This high resolution 3D model of the fluid flow in a single-screw extruder allows us to identify the position and extent of Moffatt eddies that impede mixing. We further consider the erosion of particles (e.g. carbon-black agglomerates) advected by the polymeric flow. We assume a particle to be made of primary fragments bound together. In the erosion process a primary fragment breaks out of a given particle. Particles are advected by the laminar flow and they disperse because of the shear stresses imparted by the fluid. The time evolution of the numbers of particles of different sizes is described by the Bateman coupled differential equations used to model radioactivity. Using the particle size distribution we compute an entropic fragmentation index which varies from 0 for a monodisperse system to 1 for an extreme poly-disperse system.

  18. Slurry Erosion Behavior of Destabilized and Deep Cryogenically Treated Cr-Mn-Cu White Cast Irons

    Directory of Open Access Journals (Sweden)

    S. Gupta

    2016-12-01

    Full Text Available The effects of destabilization treatment and destabilization followed by cryogenic treatment have been evaluated on the microstructural evolution and sand-water slurry erosion behavior of Cr-Mn-Cu white cast irons. The phase transformations after the destabilization and cryotreatment have been characterized by bulk hardness measurement, optical and scanning electron microscopy, x-ray diffraction analysis. The static corrosion rate has been measured in tap water (with pH=7 and the erosion-corrosion behavior has been studied by slurry pot tester using sand-water slurry. The test results indicate that the cryogenic treatment has a significant effect in minimizing the as-cast retained austenite content and transforming into martensitic and bainitic matrix embedded with ultra-fine M7C3 alloy carbides. In contrast, by conventional destabilization treatment retained austenite in the matrix are not fully eliminated. The slurry erosive wear resistance has been compared with reference to destabilized and cryotreated high chromium iron samples which are commonly employed for such applications. The cryotreated Cr-Mn-Cu irons have exhibited a comparable erosive wear performance to those of high chromium irons. Higher hardness combined with improved corrosion resistance result in better slurry erosion resistance.

  19. Hip prothesis: an in vitro wear protocol based on a comparison between gravimetric and profilometric analysis.

    Science.gov (United States)

    Affatato, S; Tagliati, M; Toni, A

    1999-01-01

    Ultra high molecular weight polyethylene acetabular cups were analysed by means of a shadowgraph method (using a profile projector) to measure linear wear. The results were compared with those of previous wear tests performed on a hip joint simulator. Twelve polyethylene acetabular cups were analysed. The specimens were evaluated visually for evidence of polyethylene wear. Examination of the polyethylene inner surface did not reveal evidence of surface failure such as delamination, fatigue cracks or scratches. Volumetric wear was calculated using a formula based on dimensional change due to the penetration of the femoral head in the acetabular cup. It was found to be of the same order of magnitude as the wear obtained in in vitro experimental tests.

  20. Wear behavior of Al-7%Si-0.3%Mg/melon shell ash particulate composites.

    Science.gov (United States)

    Abdulwahab, M; Dodo, R M; Suleiman, I Y; Gebi, A I; Umar, I

    2017-08-01

    The present study examined wear characteristics of A356/melon shell ash particulate composites. Dry-sliding the stainless steel ball against specimen disc revealed the abrasive wear behavior of the composites under loads of 2 and 5N. The composite showed lower wear rate of 2.182 × 10 -4 mm 3 /Nm at 20 wt% reinforced material under load of 5N. Results showed that wear rate decreased significantly with increasing weight percentage of melon shell ash particles. Microstructural analyses of worn surfaces of the composites reveal evidence of plastic deformation of matrix phase. The wear resistance of A356 increased considerably with percentage reinforcement. In other words, the abrasive mass loss decreased with increasing percentage of reinforcement addition at the both applied loads. The control sample suffered a highest mass loss at 5 N applied load.

  1. Recrystallization as a controlling process in the wear of some f.c.c. metals

    Science.gov (United States)

    Bill, R. C.; Wisander, D.

    1977-01-01

    Detailed examination of copper specimens after sliding against 440 C steel in liquid methane at speeds up to 25 m/s and loads of up to 2 kg showed the metal comprising the wear surface to possess a fine cell recrystallized structure. Wear proceeded by the plastic shearing of metal in this near surface region without the occurrence of visible metal transfer. A dynamic balance between the intense shear process at the surface and the nucleation of recrystallized grains was proposed to account for the behavior of the metal at the wear surface. Sliding wear experiments were also conducted on Ag, Cu-10% Al, Cu-10% Sn, Ni and Al. It was found that low wear and the absence of heavy metal transfer were associated with those metals observed to undergo recrystallization nucleation without prior recovery.

  2. Erosion mechanism and erosion products in carbon-based materials

    Energy Technology Data Exchange (ETDEWEB)

    Arkhipov, N.; Bakhtin, V.; Barsuk, V.; Kurkin, S.; Mironova, E.; Piazza, G.; Safronov, V. E-mail: vsafr@rico.ttk.ru; Scaffidi-Argentina, F.; Toporkov, D.; Vasenin, S.; Wuerz, H.; Zhitlukhin, A

    2002-12-01

    Plasma/material interaction was studied in disruption simulation experiments at the plasma gun facility MK-200. Graphite and carbon-fibre composites were exposed to pulsed energetic plasma under heat loads typically expected for disruptions in future tokamaks. Erosion rates, erosion mechanisms and the properties of the eroded carbon have been studied.

  3. Radiation tagging measures wear at speed

    International Nuclear Information System (INIS)

    Barrett, Jon.

    1994-01-01

    A new non-invasive technique for performing accelerated wear and corrosion analysis is particularly relevant to power transmission systems. Wear tests that would normally take days or weeks to complete can now be performed in hours. A tiny patch of the wearing component is made mildly radioactive and the drop in activity as material is worn away is monitored. Known as Thin Layer Activation (TLA), the technology was originally developed and pioneered in-house by the Atomic Energy Authority. Since then, the dominant partner has been the automotive sector where TLA has been used extensively for engine wear and lubrication performance analysis. However, TLA could be used in any wear or corrosion environment. Applications include wear analysis of machine tool cutting surfaces, pump impellers and brake linings to the corrosion monitoring of process plant and pipelines. (author)

  4. Wear mechanisms in ceramic hip implants.

    Science.gov (United States)

    Slonaker, Matthew; Goswami, Tarun

    2004-01-01

    The wear in hip implants is one of the main causes for premature hip replacements. The wear affects the potential life of the prosthesis and subsequent removals of in vivo implants. Therefore, the objective of this article is to review various joints that show lower wear rates and consequently higher life. Ceramics are used in hip implants and have been found to produce lower wear rates. This article discusses the advantages and disadvantages of ceramics compared to other implant materials. Different types of ceramics that are being used are reviewed in terms of the wear characteristics, debris released, and their size together with other biological factors. In general, the wear rates in ceramics were lower than that of metal-on-metal and metal-on-polyethylene combinations.

  5. A review of the erosion of thermal barrier coatings

    International Nuclear Information System (INIS)

    Wellman, R G; Nicholls, J R

    2007-01-01

    The application of thermal barrier coatings (TBCs) to components with internal cooling in the hot gas stream of gas turbine engines has facilitated a steep increase in the turbine entry temperature and the associated increase in performance and efficiency of gas turbine engines. However, TBCs are susceptible to various life limiting issues associated with their operating environment including erosion, corrosion, oxidation, sintering and foreign object damage (FOD). This is a review paper that examines various degradation and erosion mechanisms of TBCs, especially those produced by electron beam physical vapour deposition (EB-PVD). The results from a number of laboratory tests under various impact conditions are discussed before the different erosion and FOD mechanisms are reviewed. The transitions between the various erosion mechanisms are discussed in terms of the D/d ratio (contact area diameter/column diameter), a relatively new concept that relates the impact size to the erosion mechanism. The effects of ageing, dopant additions and calcium-magnesium-alumina-silicates on the life of TBCs are examined. It is shown that while ageing increases the erosion rate of EB-PVD TBCs, ageing of plasma sprayed TBCs in fact lowers the erosion rate. Finally modelling of EB-PVD TBCs is briefly introduced. (topical review)

  6. Do erosion control and snakes mesh?

    Science.gov (United States)

    Christopher Barton; Karen Kinkead

    2005-01-01

    In the battle to curb soil erosion and sedimentation, numberous techniques and products for controlling erosion and sedimentation have been developed and are being implemented. Rolled erosion control products, such as a temporary erosion control blankets and permanent turf reinforcement mats, represent one type of erosion control product that has been used extensively...

  7. Rill erosion rates in burned forests

    Science.gov (United States)

    Joseph W. Wagenbrenner; Peter R. Robichaud

    2011-01-01

    Introduction Wildfires often produce large increases in runoff and erosion rates (e.g., Moody and Martin, 2009), and land managers need to predict the frequency and magnitude of postfire erosion to determine the needs for hazard response and possible erosion mitigation to reduce the impacts of increased erosion on public safety and valued resources. The Water Erosion...

  8. The Delamination Theory of Wear - III

    Science.gov (United States)

    1977-12-01

    purposes: to predict wear arnd to reduce wear, Mathematical modelo are necessary in order to predict wear 40 qualitatively. They are also useful in the...Jersey 08540 The Ohio State University 116 West 19th Avenue Dr. E. Rudy .I Columbus, Ohio 43210 Oregon Graduate Center 19600 N.W. Walker Road Mr. W...Smith Baverton, Oregon 97005 Code 2832 Naval Ship Research and Development Dr. W. Ruff I Annopolis, Maryland 21401 National Bureau of Standards Department

  9. The influence of boron on the abrasion wear resistance of 17%Cr white cast iron

    International Nuclear Information System (INIS)

    Yan, P.; Zhou, Q.

    1987-01-01

    A study of the abrasion wear resistance of the 2.7C-17Cr-0.7Mo white cast irons with different structures alloyed with boron ranging from 0.1% to 1.3% is carried out. Eleven heat treatments were used to find the optimum treatment. Three conditions (as-cast, martensitic and austenitic) are adopted for various tests. The microstructure and three-dimensional morphology of compounds are examined by optical microscope and SEM respectively. X-ray diffractometer is employed to analyze the compound phases. A high-stress abrasive wear tests is performed with loose SiO/sub 2/ and SiC abrasives in a metal track wear tester. Another abrasive wear test is conducted with wet SiO/sub 2/ abrasives in a rubber wheel tester. The hardness and fracture toughness of these alloys was also measured. With increasing boron content fracture toughness decreases. It is noted that if the irons contained about same compound volume, the abrasion wear resistance in present wear systems are much better than the irons without boron against SiO/sub 2/ abrasives, and the toughness is equivalent to 15 Cr irons without boron. Finally, considering the wear resistance and fracture toughness, the test results would provide a basis for optimizing these properties in selecting materials for a given wear component

  10. Are resin composites suitable replacements for amalgam? A study of two-body wear.

    Science.gov (United States)

    Lazaridou, Dimitra; Belli, Renan; Petschelt, Anselm; Lohbauer, Ulrich

    2015-07-01

    Wear resistance is an important property of the dental materials, particularly for large restorations in the posterior regions and for the patients suffering from parafunctional activities. Additionally, the wear resistance of flowable composite resin materials is a clinical concern, although they are popular among dentists because of their easy handling. The aims of the present study were to evaluate the wear resistance of nine composite resins both condensable (G-aenial posterior, Venus, GrandioSO, Tetric EvoCeram, Ceram X duo, Filtek Supreme XTE) and new-generation flowable resin composites (G-aenial Universal Flo, GrandioSO Flow and GrandioSO Heavy Flow) and to compare these results with amalgam. Eight specimens of each material were subjected to two-body wear tests, using a chewing simulator. The wear region of each material was examined under profilometer, measuring the vertical loss (μm) and the volume loss (mm(3)) of the materials. Additionally, SEM analysis was performed to assess surfaces irregularities. The results showed significant difference of the vertical loss and the volume loss of the examined materials (p amalgam had the best wear resistance, two condensable resin composites (GrandioSO, Ceram X duo) and all flowable materials had no significant difference with amalgam. GrandioSO had the highest wear resistance and Filtek Supreme XTE the lowest wear resistance. The majority of resin composites had good wear resistance and similar to amalgam. Based on the in vitro measurements of two-body wear resistance, the new resin composites could replace amalgam for restorations placed in occlusal stress-bearing regions. New-generation flowable resin materials may also be used in occlusal contact restorations.

  11. Eccrine syringofibroadenoma in a patient with erosive palmoplantar lichen planus.

    Science.gov (United States)

    French, L E; Masgrau, E; Chavaz, P; Saurat, J H

    1997-01-01

    We report the case of an 82-year-old woman with a 6-year history of erosive palmoplantar lichen planus associated with eccrine syringofibroadenoma (ESFA). Examination revealed a well-demarcated patche writish of reticulated whitish papular lesions in skin of otherwise normal appearance at the border of erosive lichen planus plaques. These lesions had the histological appearance of ESFA. We suggest that these lesions are induced by the inflammatory remodelling associated with erosive lichen planus and propose to consider ESFA in the context of skin tissue remodelling as a new subtype of ESFA.

  12. Simulated studies of wear and friction in total hip prosthesis components with various ball sizes and surface finishes

    Science.gov (United States)

    Swikert, M. A.; Johnson, R. L.

    1976-01-01

    Experiments were conducted on a newly designed total hip joint simulator. The apparatus closely simulates the complex motions and loads of the human hip in normal walking. The wear and friction of presently used appliance configurations and materials were determined. A surface treatment of the metal femoral ball specimens was applied to influence wear. The results of the investigation indicate that wear can be reduced by mechanical treatment of metal femoral ball surfaces. A metallographic examination and surface roughness measurements were made.

  13. Determination of rail wear and short-time wear measurements of rails applying radioisotopes

    International Nuclear Information System (INIS)

    Grohmann, H.D.

    1981-01-01

    An energetic model has been developed for calculating rail wear. Short-time wear tests on rails after surface activation and following activity measurements showed a good agreement with the calculated values

  14. Structure effect on wear resistance of alloys

    International Nuclear Information System (INIS)

    Stepina, A.I.; Sidorova, L.I.; Tolstenko, E.V.

    1982-01-01

    The dependence of wear resistance on hardness of steels with different microstructure is studied under conditions of gas-abrasion wear of surface layers. It is found out that at the same hardness the wear resistance of α-alloys is higher than that of γ-alloys in spite of considerable surface hardening of austenitic alloys. Fracture of surface in the process of abrasive wear occurs after achievement of definite values of microhardness and the width of a diffraction line for each structural class of alloys [ru

  15. Friction & Wear Under Very High Electromagnetic Stress

    National Research Council Canada - National Science Library

    Cowan, Richard S; Danyluk, Steven; Moon, Francis; Ford, J. C; Brenner, Donald W

    2004-01-01

    This document summarizes initial progress toward advancing the fundamental understanding of the friction, wear and mechanics of interfaces subjected to extreme electromagnetic stress, high relative...

  16. Rainfall erosivity: An historical review

    Science.gov (United States)

    Rainfall erosivity is the capability of rainfall to cause soil loss from hillslopes by water. Modern definitions of rainfall erosivity began with the development of the Universal Soil Loss Equation (USLE), where rainfall characteristics were statistically related to soil loss from thousands of plot...

  17. Effect of crystallographic orientation on erosion characteristics of arc evaporation titanium nitride coating

    International Nuclear Information System (INIS)

    Sue, J.A.; Troue, H.H.

    1987-01-01

    Recent development of TiN coatings specifically for erosion protection has focused on better process control as well as crystallographic orientation. The erosion behavior of TiN coatings, which were produced by the arc evaporation process, was evaluated using 27 μm angular alumina particles at a velocity of 91 ms -1 . The eroded surfaces were examined in a scanning electron microscope, and erosion mechanisms in response to the oblique and normal impacts were characterized. The erosion characteristics of various TiN coatings are presented. The variation of surface morphology, microstructure, hardness and erosion characteristics of the coating with crystallographic orientation is also discussed. (orig.)

  18. Rainfall Erosivity in Europe

    DEFF Research Database (Denmark)

    Panagos, Panos; Ballabio, Cristiano; Borrelli, Pasquale

    2015-01-01

    on the best available datasets. Data have been collected from 1541 precipitation stations in all European Union (EU) Member States and Switzerland, with temporal resolutions of 5 to 60 min. The R-factor values calculated from precipitation data of different temporal resolutions were normalised to R......-factor values with temporal resolutions of 30 min using linear regression functions. Precipitation time series ranged from a minimum of 5 years to a maximum of 40 years. The average time series per precipitation station is around 17.1 years, the most datasets including the first decade of the 21st century....... Gaussian Process Regression (GPR) has been used to interpolate the R-factor station values to a European rainfall erosivity map at 1 km resolution. The covariates used for the R-factor interpolation were climatic data (total precipitation, seasonal precipitation, precipitation of driest/wettest months...

  19. In-Situ Measurement of Hall Thruster Erosion Using a Fiber Optic Regression Probe

    Science.gov (United States)

    Polzin, Kurt; Korman, Valentin

    2009-01-01

    One potential life-limiting mechanism in a Hall thruster is the erosion of the ceramic material comprising the discharge channel. This is especially true for missions that require long thrusting periods and can be problematic for lifetime qualification, especially when attempting to qualify a thruster by analysis rather than a test lasting the full duration of the mission. In addition to lifetime, several analytical and numerical models include electrode erosion as a mechanism contributing to enhanced transport properties. However, there is still a great deal of dispute over the importance of erosion to transport in Hall thrusters. The capability to perform an in-situ measurement of discharge channel erosion is useful in addressing both the lifetime and transport concerns. An in-situ measurement would allow for real-time data regarding the erosion rates at different operating points, providing a quick method for empirically anchoring any analysis geared towards lifetime qualification. Erosion rate data over a thruster s operating envelope would also be useful in the modeling of the detailed physics inside the discharge chamber. There are many different sensors and techniques that have been employed to quantify discharge channel erosion in Hall thrusters. Snapshots of the wear pattern can be obtained at regular shutdown intervals using laser profilometry. Many non-intrusive techniques of varying complexity and sensitivity have been employed to detect the time-varying presence of erosion products in the thruster plume. These include the use quartz crystal microbalances, emission spectroscopy, laser induced flourescence, and cavity ring-down spectroscopy. While these techniques can provide a very accurate picture of the level of eroded material in the thruster plume, it is more difficult to use them to determine the location from which the material was eroded. Furthermore, none of the methods cited provide a true in-situ measure of erosion at the channel surface while

  20. Spatial and temporal variations of wind erosion climatic erosivity in the farming-pastoral zone of Northern China

    Science.gov (United States)

    Yue, Shuping; Yang, Ruixin; Yan, Yechao; Yang, Zhengwei; Wang, Dandan

    2018-03-01

    Wind erosion climatic erosivity is an important parameter to assess the possible effects of climatic conditions on wind erosion. In this paper, the wind erosion climatic factor (C-factor), which was used to quantify the wind erosion climatic erosivity, was calculated for the period 1960-2014 based on monthly meteorological data collected from 101 stations in the farming-pastoral zone of Northern China. The Mann-Kendall (M-K) test, trend analysis, and geostatistical analysis methods were used to explore the spatial and temporal characteristics of the wind erosion climatic erosivity in this region. The result suggests that the annual C-factor, with a maximum of 76.05 in 1969 and a minimum of 26.57 in 2007, has a significant decreasing trend over the past 55 years. Strong seasonality in the C-factor was found, with the highest value in spring, which accounts for a significant proportion of the annual C-factor (41.46%). However, the coefficient of variation of the seasonal C-factor reaches a maximum in winter and a minimum in spring. The mean annual C-factor varies substantially across the region. Areas with high values of the mean annual C-factor (C ≥ 100) are located in Ulanqab and Dingxi, while areas with low values (C ≤ 10) lie in Lanzhou, Linxia, Dingxi, Xining, and Chengde. Spatial analysis on the trend of the C-factor reveals that 81% of the stations show statistically significant decreases at a 90% confidence level. An examination of the concentration ratio of the C-factor shows that the wind erosion climatic erosivity is concentrated in spring, especially in April, which makes this period particularly important for implementing soil conservation measures.

  1. The Abrasive Wear Resistance of Chromium Cast Iron

    Directory of Open Access Journals (Sweden)

    Kopyciński D.

    2014-03-01

    Full Text Available The resistance of cast iron to abrasive wear depends on the metal abrasive hardness ratio. For example, hardness of the structural constituents of the cast iron metal matrix is lower than the hardness of ordinary silica sand. Also cementite, the basic component of unalloyed white cast iron, has hardness lower than the hardness of silica. Some resistance to the abrasive effect of the aforementioned silica sand can provide the chromium white cast iron containing in its structure a large amount of (Cr, Fe7C3 carbides characterised by hardness higher than the hardness of the silica sand in question. In the present study, it has been anticipated that the white cast iron structure will be changed by changing the type of metal matrix and the type of carbides present in this matrix, which will greatly expand the application area of castings under the harsh operating conditions of abrasive wear. Moreover, the study compares the results of abrasive wear resistance tests performed on the examined types of cast iron. Tests of abrasive wear resistance were carried out on a Miller machine. Samples of standard dimensions were exposed to abrasion in a double to-and-fro movement, sliding against the bottom of a trough filled with an aqueous abrasive mixture containing SiC + distilled water. The obtained results of changes in the sample weight were approximated with a power curve and shown further in the study.

  2. Problems of locomotive wheel wear in fleet replacement

    Directory of Open Access Journals (Sweden)

    L.P. Lingaytis

    2013-08-01

    Full Text Available Purpose. To conduct a research and find out the causes of defects appearing on the wheel thread of freight locomotives 2М62 and SIEMENS ER20CF. Methodology. To find the ways to solve this problem comparing the locomotive designs and their operating conditions. Findings. After examining the nature of the wheel wear the main difference was found: in locomotives of the 2M62 line wears the wheel flange, and in the locomotives SIEMENS ER20CF – the tread surface. After installation on the 2M62 locomotive the lubrication system of flanges their wear rate significantly decreased. On the new freight locomotives SIEMENS ER20CF the flange lubrication systems of the wheel set have been already installed at the factory, however the wheel thread is wearing. As for locomotives 2M62, and on locomotives SIEMENS ER20CF most wear profile skating wheels of the first wheel set. On both locomotive lines the 2М62 and the SIEMENS ER20CF the tread profile of the first wheel set most of all is subject to the wear. After reaching the 170 000 km run, the tread surface of some wheels begins to crumble. There was a suspicion that the reason for crumb formation of the wheel surface may be insufficient or excessive wheel hardness or its chemical composition. In order to confirm or deny this suspicion the following studies were conducted: the examination of the rim surface, the study of the wheel metal hardness and the document analysis of the wheel production and their comparison with the results of wheel hardness measurement. Practical value. The technical condition of locomotives is one of the bases of safety and reliability of the rolling stock. The reduction of the wheel wear significantly reduces the operating costs of railway transport. After study completion it was found that there was no evidence to suggest that the ratio of the wheel-rail hardness could be the cause of the wheel surface crumbling.

  3. Abrasive wear behaviour of electrodeposited nanocrystalline materials

    Science.gov (United States)

    Jeong, Daehyun

    The effect of grain size refinement on the abrasive wear behaviour of nanocrystalline Ni, Ni-P and Co electrodeposits and the critical materials properties that influence the abrasive wear resistance were studied using the Taber wear test. As the grain size of Ni decreased from 90 mum to 13 nm, the dominant abrasive wear mode changed from ploughing to cutting and the Taber wear resistance was considerably improved by the increases in hardness and surface elastic properties. The abrasive wear behaviour of Ni with various grain sizes can be described using the attack angle model, which takes into consideration the randomly dispersed Al2O3 abrasive particles in the Taber wheel with various sizes, shapes and orientations. Depending on the phosphorus content, the nickel-phosphorus (Ni-P) alloys containing up to 6 wt.% P had nanocrystalline or mixed nanocrystalline-amorphous structures and both regular and inverse Hall-Petch behaviour were observed as a result of the microstructural changes with increasing P content/decreasing grain size. The wear resistance, like hardness, followed the Hall-Petch type behaviour, demonstrating that the smallest grain size does not necessarily provide the best wear resistance. For all Ni-P alloys, the wear resistance was improved by heat treatment due to Ni3P precipitates and, for materials with high P content, nanocrystallization of the amorphous phase. For heat-treated Ni-P alloys, however, the highest hardness did not give the best wear resistance. Despite the grain size reduction of Co from 10 mum to 17 nm, there was no significant change in the wear resistance due to the unusually high degree of plastic deformation of the nanocrystalline material. In addition to hardness and surface elastic properties which are usually considered important material properties that control the abrasive wear resistance, Taber wear ductility was introduced as a new material intrinsic property which can be applied to explain abrasive wear resistance for

  4. Antagonist wear by polished zirconia crowns.

    Science.gov (United States)

    Hartkamp, Oliver; Lohbauer, Ulrich; Reich, Sven

    The aim of this in vivo study was to measure antagonist wear caused by polished monolithic posterior zirconia crowns over a 24-month period using the intraoral digital impression (IDI) technique. Thirteen zirconia crowns were placed in nine patients. The crowns and adjacent teeth were captured using an intraoral scanner (Lava C.O.S.). The corresponding antagonist teeth and the respective neighboring teeth were also scanned. Scanning was performed immediately after the restoration (baseline) as well as 12 and 24 months after crown placement. Geomagic Qualify software was used to superimpose the follow-up data sets onto the corresponding baseline data set, identify wear sites, and measure maximum vertical height loss in each individual wear site. Overall antagonist wear was then determined as the mean of wear rates measured in all of the individual antagonist units. In addition, wear rates in enamel and ceramic antagonists were analyzed as part of the scope of this study. The maximum mean wear with standard deviation (SD) in the overall sample with a total of nine patients, 13 antagonist units, and 98 evaluable wear sites was 86 ± 23 µm at 12 months, and 103 ± 39 µm at 24 months. The maximum mean wear in the enamel antagonist subgroup was 87 ± 41 µm at 12 months, and 115 ± 71 µm at 24 months; and in the ceramic antagonist subgroup 107 ± 22 µm at 12 months, and 120 ± 27 µm at 24 months. The wear rates determined in this study are comparable to those of existing studies. The IDI technique of wear analysis can be carried out in a practical manner and produces useful results.

  5. Using REE tracers to measure sheet erosion changing to rill erosion

    International Nuclear Information System (INIS)

    Liu Puling; Xue Yazhou; Song Wei; Wang Mingyi; Ju Tongjun

    2004-01-01

    Rare Earth Elements (REE) tracer method was used to study sheet erosion changing to rill erosion on slope land. By placing different rare earth elements of different soil depth across a slope in an indoor plot, two simulated rainfalls were applied to study the change of erosion type and the rill erosion process. The results indicate that the main erosion type is sheet erosion at the beginning of the rainfalls, and serious erosion happens after rill erosion appears. Accumulated sheet and rill erosion amounts increase with the rainfalls time. The percentage of sheet erosion amount decreases and rill erosion percentage increases with time. At the end of the rainfalls, the total rill erosion amounts are 4-5 times more than sheet erosion. In this paper, a new REE tracer method was used to quantitatively distinguish sheet and rill erosion amounts. The new REE tracer method should be useful to future studying of erosion processes on slope lands. (authors)

  6. Erosion-corrosion resistance of engineering materials in various test conditions

    OpenAIRE

    Rajahram, S.S; Harvey, T.J.; Wood, R.J.K.

    2009-01-01

    Erosion–corrosion is a complex phenomenon which involves the interaction between the mechanical processes of solid particle erosion and the electrochemical processes of corrosion. A whole range of issues is faced by a designer when trying to obtain relevant information on erosion–corrosion performance of a material. Amongst the constraints are the dispersed test conditions and test rigs available in the literature making comparisons and quantifying erosion–corrosion wear rates of different ma...

  7. Comparison of methods for calculating water erosion

    OpenAIRE

    SVOBODOVÁ, Pavlína

    2011-01-01

    Bachelor thesis presents a comparison of methods for calculating water erosion. The aim is to summarize available evidence concerning the problems of water erosion. There are presented some methods how to calculate average annual erosion of soils, and selected models for calculating the erosion immediately. There are also listed possible erosion control measures through which we can at least slow the effects of erosion, rather than stop completely.

  8. Impact erosion model for gravity-dominated planetesimals

    Science.gov (United States)

    Genda, Hidenori; Fujita, Tomoaki; Kobayashi, Hiroshi; Tanaka, Hidekazu; Suetsugu, Ryo; Abe, Yutaka

    2017-09-01

    Disruptive collisions have been regarded as an important process for planet formation, while non-disruptive, small-scale collisions (hereafter called erosive collisions) have been underestimated or neglected by many studies. However, recent studies have suggested that erosive collisions are also important to the growth of planets, because they are much more frequent than disruptive collisions. Although the thresholds of the specific impact energy for disruptive collisions (QRD*) have been investigated well, there is no reliable model for erosive collisions. In this study, we systematically carried out impact simulations of gravity-dominated planetesimals for a wide range of specific impact energy (QR) from disruptive collisions (QR ∼ QRD*) to erosive ones (QR QR, but that it can be nicely scaled by QRD* for the parameter ranges investigated (Rtar = 30-300 km, vimp = 2-5 km/s). This means that Mej/Mtot depends only on QR/QRD* in these parameter ranges. We confirmed that the collision outcomes for much less erosive collisions (QR QR/QRD* holds. For disruptive collisions (QR ∼ QRD*), the curvature of the target has a significant effect on Mej/Mtot. We also examined the angle-averaged value of Mej/Mtot and found that the numerically obtained relation between angle-averaged Mej/Mtot and QR/QRD* is very similar to the cases for θ = 45° impacts. We proposed a new erosion model based on our numerical simulations for future research on planet formation with collisional erosion.

  9. Influence of microstructure on high-stress abrasive wear behaviour of a microalloyed steel

    Directory of Open Access Journals (Sweden)

    Ankita Bhattacharya

    2016-09-01

    Full Text Available This investigation examines two-body abrasive wear behaviour of ferrite–pearlite (FP, ferrite–bainite (FB and ferrite–martensite (FM microstructures of a microalloyed steel with nearly same amount of second phase/phase mixture to understand the role microstructure on high-stress abrasive wear performance of steel. Wear tests of differently heat treated specimens against SiC abrasive paper have been conducted over a wide range of sliding distance and normal load. This has been supplemented by the examinations of worn surfaces and generated wear debris in addition to the characterization of microstructures and evaluation of mechanical properties. It has been observed that for all type of microstructures, wear rate increases with increasing load but remains constant with sliding distance. Interestingly, the magnitude of wear rate at any particular wear condition is found to decrease considerably in the order of FP, FB and FM structure due to increased resistance to plastic deformation and microcutting encountered during the course of abrasion.

  10. Rod examination gauge

    Energy Technology Data Exchange (ETDEWEB)

    Bacvinskas, W.S.; Bayer, J.E.; Davis, W.W.; Fodor, G.; Kikta, T.J.; Matchett, R.L.; Nilsen, R.J.; Wilczynski, R.

    1991-12-31

    The present invention is directed to a semi-automatic rod examination gauge for performing a large number of exacting measurements on radioactive fuel rods. The rod examination gauge performs various measurements underwater with remote controlled machinery of high reliability. The rod examination gauge includes instruments and a closed circuit television camera for measuring fuel rod length, free hanging bow measurement, diameter measurement, oxide thickness measurement, cladding defect examination, rod ovality measurement, wear mark depth and volume measurement, as well as visual examination. A control system is provided including a programmable logic controller and a computer for providing a programmed sequence of operations for the rod examination and collection of data.

  11. ROLLING CONTACT FATIGUE AND WEAR OF CrL AND CrM MODE POWDER METALLURGY STEELS

    Directory of Open Access Journals (Sweden)

    Dušan Rodziňák

    2010-03-01

    Full Text Available Contact fatigue properties of sintered steels type CrM and CrL with addition of 0,3-0,7 %C were examined on the device type „pin on disc“ and confronted with wear tests on the same principle. Achieved outcomes are better for CrM material; the higher carbon content the better they are. Fatigue strength ranges from 925 - 1410 MPa and is consistent with the value of hardness. Dry wear tests show that the wear is dependent on the hardness of carbide particles (microhardness and not on macrohardness of material. These causes wear of indentor. Between values obtained from tests of contact fatigue and wear testing is not possible to find relevant compliance. Both rupture mechanisms are based on breaches of other principles, particularly the PM materials are in the mode of wear that is not sufficiently explored.

  12. Relation between in-vitro wear and nanomechanical properties of commercial light-cured dental composites coated with surface sealants

    Directory of Open Access Journals (Sweden)

    Emanuel Santos Jr

    2013-01-01

    Full Text Available This work investigates the correlation between the in-vitro wear resistance and the nanomechanical properties of dental sealants commercially available. Mechanical properties, namely hardness (H and elastic modulus (E, were assessed by nanoindentation technique. The coated samples presented lower H and E values than the Z250 composite resin substrate. Such measurements were used to calculate H/E ratios. Wear tests were carried out in water by using a pin-on-plate apparatus. Scars formed on the samples were qualitatively examined by optical microscopy, while their wear depths were measured by contact profilometry. Based on the findings, an empirical correlation between the wear depths and H/E was obtained. A high H/E ratio was associated to surfaces with enhanced wear resistance. For the tribological conditions here employed, the H/E ratio could be, therefore, considered a useful parameter for ranking the in-vitro wear of dental sealants.

  13. Abrasive tool wear in metal forming processes

    NARCIS (Netherlands)

    Masen, Marc Arthur

    2004-01-01

    In this work a model is presented that quantifies this abrasive tool wear. The foundation of the model is on the level of surface roughness. The surface micro-geometry of both the abrasive surface and the wearing tool are measured using an interferometer. Based on this data, the surface geometry in

  14. Truck tyre wear assessment and prediction

    NARCIS (Netherlands)

    Lupker, H.A.; Montanaro, F.; Donadio, D.; Gelosa, E.; Vis, M.A.

    2002-01-01

    Tyre wear is a complex phenomenon. It depends non-linearly on numerous parameters, like tyre compound and design, vehicle type and usage, road conditions and road surface characteristics, environmental conditions (e.g., temperature) and many others. Yet, tyre wear has many economic and ecological

  15. Wear Calculation Approach for Sliding - Friction Pairs

    Science.gov (United States)

    Springis, G.; Rudzitis, J.; Lungevics, J.; Berzins, K.

    2017-05-01

    One of the most important things how to predict the service life of different products is always connected with the choice of adequate method. With the development of production technologies and measuring devices and with ever increasing precision one can get the appropriate data to be used in analytic calculations. Historically one can find several theoretical wear calculation methods but still there are no exact wear calculation model that could be applied to all cases of wear processes because of difficulties connected with a variety of parameters that are involved in wear process of two or several surfaces. Analysing the wear prediction theories that could be classified into definite groups one can state that each of them has shortcomings that might impact the results thus making unnecessary theoretical calculations. The offered wear calculation method is based on the theories of different branches of science. It includes the description of 3D surface micro-topography using standardized roughness parameters, explains the regularities of particle separation from the material in the wear process using fatigue theory and takes into account material’s physical and mechanical characteristics and definite conditions of product’s working time. The proposed wear calculation model could be of value for prediction of the exploitation time for sliding friction pairs thus allowing the best technologies to be chosen for many mechanical details.

  16. Straylight Measurements in Contact Lens Wear

    NARCIS (Netherlands)

    van der Meulen, Ivanka J. E.; Engelbrecht, Leonore A.; van Vliet, Johannes M. J.; Lapid-Gortzak, Ruth; Nieuwendaal, Carla P.; Mourits, Maarten P.; Schlingemann, Reinier O.; van den Berg, Thomas J. T. P.

    2010-01-01

    Purpose: (1) To quantify the effect of contact lens wear on straylight in rigid and soft contact lens wearers and (2) to relate findings to morphological changes and subjective complaints. Methods: Straylight was measured using the Oculus C-Quant during contact lens wear and after contact lens

  17. Enamel wear opposing polished and aged zirconia.

    Science.gov (United States)

    Burgess, J O; Janyavula, S; Lawson, N C; Lucas, T J; Cakir, D

    2014-01-01

    Aging of dental zirconia roughens its surface through low temperature degradation. We hypothesized that age-related roughening of zirconia crowns may cause detrimental wear to the enamel of an opposing tooth. To test our hypothesis, we subjected artificially aged zirconia and reference specimens to simulated mastication in a wear device and measured the wear of an opposing enamel cusp. Additionally, the roughness of the pretest surfaces was measured. The zirconia specimens, artificially aged by autoclave, showed no significant increase in roughness compared to the nonaged specimens. Furthermore, no significant difference in material or opposing enamel wear between the aged and nonaged zirconia was seen. All zirconia specimens showed less material and opposing enamel wear than the enamel to enamel control or veneering porcelain specimens. Scanning electron micrographs showed relatively smooth surfaces of aged and nonaged zirconia following wear testing. The micrographs of the veneering ceramic showed sharp fractured edges and fragments of wear debris. Zirconia may be considered a wear-friendly material for restorations opposing enamel, even after simulated aging.

  18. Sliding wear resistance of iron aluminides

    Indian Academy of Sciences (India)

    Unknown

    ordered intermetallic alloy (Johnson et al 1990, 1994,. 1996; Maupin et al 1992, 1993; Tu and Liu 1997; Kim and Kim 1998). Maupin et al (1992, 1993) had shown that the Fe3Al alloy having DO3 structure possesses mar- ginally lower wear rate than those with B2 structure. The wear resistance of Fe3Al alloy was found to ...

  19. Corrosion of amalgams under sliding wear.

    Science.gov (United States)

    Lian, K; Meletis, E I

    1996-05-01

    During mastication, dental amalgams are simultaneously subjected to corrosion by the oral environment and to a sliding-wear process by biting forces. In the present study, the effect of sliding wear on the corrosion behavior of two high-copper dental amalgams was investigated. An experimental apparatus was utilized that allows electrochemical testing under sliding-wear conditions. Corrosion potential measurements and anodic polarization scans were conducted in 0.1 M NaCl solution under sliding wear to characterize the behavior of two commercial, high-copper, single composition dental amalgams. In addition, long duration tests were conducted to assess possible corrosion and wear synergistic effects. The results showed that sliding wear caused a sharp reduction in the corrosion potential, a significant increase in the corrosion rate and a decrease in the repassivation rate of both amalgams. These effects are due to the mechanical removal by the wear process of the surface protective film formed on dental amalgams. The simultaneous action of sliding wear and corrosion can also induce embrittlement that leads to cracking. The present evidence suggests that this cracking may be one of the major contributors to marginal failures of dental amalgam restorations.

  20. Erosion and deposition in tokamaks

    International Nuclear Information System (INIS)

    Staudenmaier, G.

    1985-01-01

    The flow of metal impurities from the wall and limiter to the plasma, and back towards the wall, is investigated using surface collection probes and subsequent surface analysis in order to understand impuritiy generation and impurity transport. Impurity fluxes and their scrapeoff lengths have been investigated for several years in a large number of tokamaks. The results are summarized and discussed. Erosion exceeding deposition was first observed to occur at limiterlike structures closest to the plasma edge. Recently, a new probe has been developed to measure quantitatively the erosion in ASDEX. Subsequent quantitative surface analysis is performed in situ by electron induced x-ray analysis. Erosion caused either by ions (limiter) or charge exchange neutrals (wall) can be investigated separately. The erosion at the wall is about two orders of magnitude smaller than the erosion at limiterlike structures, which is of the order of one monolayer per discharge. Simultaneous measurements of deposition and erosion have been performed to elucidate net values of deposition and erosion

  1. Asphalt wear and pollution transport

    Energy Technology Data Exchange (ETDEWEB)

    Lindgren, Asa [Division of Traffic Engineering, Lulea University of Technology Lulea (Sweden)

    1996-09-06

    Studded tires cause extensive wear of road surfaces during winter producing small particles. Besides transporting different adsorbed pollutants these particles also discharge metal ions by their own natural content. The major part (95%) of the asphalt is composed of stone fractions. The rest consists mainly of bitumen, which contains trace quantities of metals. Laboratory studies in this study have demonstrated different adsorbing properties of metal ions, as well as differences in adsorption when comparing stone materials. Two stone materials, a gabbro and a porphyry, have been tested for their adsorption properties concerning Pb, Cu, Zn and Cd. The gabbro showed better adsorption capacity than the porphyry. Gabbro has coarser grains, it is softer, and also has a higher content of most metals compared to the porphyry. In all tests lead and copper are more adsorbed than zinc and cadmium. All metal ions are released at about the same pH ({approx}4)

  2. Complications caused by contact lens wearing.

    Science.gov (United States)

    Beljan, Jasna; Beljan, Kristina; Beljan, Zdravko

    2013-04-01

    Complications in wearing contact lenses are very rare and caused by poor maintenance, over-extended wear and wearing of contact lenses in a polluted environment. Regular control by a professional person can efficiently reduce the number of complications. This paper describes the most common risks factors for complications, and complications of wearing contact lenses with the classification according to the anatomic parts of the eye: eyelids, tear film, limbus, corneal epithelium, corneal stroma and corneal endothelium. Every complication has been described by the characteristic signs and symptoms, etiology and pathology, as well as therapy and prognosis. The paper describes how to select adequate customers as contact lens users, with proper education in order to ensure minimal incidence of complications due to contact lens wear, thus attracting a lot of satisfied and healthy customers.

  3. The friction wear of electrolytic composite coatings

    International Nuclear Information System (INIS)

    Starosta, R.

    2002-01-01

    The article presents the results of investigation of wear of galvanic composite coatings Ni-Al 2 O 3 and Ni-41%Fe-Al 2 O 3 . The diameter of small parts of aluminium oxide received 0.5; 3; 5 μm. Investigations of friction sliding were effected on PT3 device at Technical University of Gdansk. Counter sample constituted a funnel made of steel NC6 (750 HV). Increase of wear coatings together with the rise of iron content in matrix is observed. The rise of sizes of ceramic particles caused decrease of wear of composite coatings, but rise of steel funnel wear. The friction coefficient increased after ceramic particle s were built in coatings. The best wear resistance characterized Ni-41%Fe-Al 2 O 3 coatings containing 2.2x10 6 mm -2 ceramic particles. (author)

  4. Mechanisms for fatigue and wear of polysilicon structural thinfilms

    Energy Technology Data Exchange (ETDEWEB)

    Alsem, Daniel Henricus [Univ. of California, Berkeley, CA (United States)

    2006-01-01

    Fatigue and wear in micron-scale polysilicon structural films can severely impact the reliability of microelectromechanical systems (MEMS). Despite studies on fatigue and wear behavior of these films, there is still an on-going debate regarding the precise physical mechanisms for these two important failure modes. Although macro-scale silicon does not fatigue, this phenomenon is observed in micron-scale silicon. It is shown that for polysilicon devices fabricated in the MUMPs foundry and SUMMiT process stress-lifetime data exhibits similar trends in ambient air, shorter lifetimes in higher relative humidity environments and no fatigue failure at all in high vacuum. Transmission electron microscopy of the surface oxides of the samples show an approximate four-fold thickening of the oxide at stress concentrations after fatigue failure, but no thickening after fracture in air or after fatigue cycling in vacuo. It is found that such oxide thickening and fatigue failure (in air) occurs in devices with initial oxide thicknesses of ~4-20 nm. Such results are interpreted and explained by a reaction layer fatigue mechanism; specifically, moisture-assisted subcritical cracking within a cyclic stress-assisted thickened oxide layer occurs until the crack reaches a critical size to cause catastrophic failure. Polysilicon specimens from the SUMMiT process are used to study wear mechanisms in micron-scale silicon in ambient air. Worn parts are examined by analytical scanning and transmission electron microscopy, while temperature changes are monitored using infrared microscopy. These results are compared with the development of values of static coefficients of friction (COF) with number of wear cycles. Observations show amorphous debris particles (~50-100 nm) created by fracture through the silicon grains (~500 nm), which subsequently oxidize, agglomerate into clusters and create plowing tracks. A nano-crystalline layer (~20-200 nm) forms at worn regions. No dislocations or

  5. Adhesive Wear of Rollers in Vacuum

    Science.gov (United States)

    Shaeef, Iqbal; Krantz, Timothy L.

    2012-01-01

    This work was done to support NASA's James Webb Space Telescope that is equipped with a Near Infrared Camera and Spectrograph and Micro Shutter Assembly (MSA). A MSA mechanism's qualification test in cryogenic vacuum at 30deg K for 96K cycles resulted in roller wear and formation of some debris. Lab tests in vacuum were conducted at NASA Glenn Research Center (GRC) to understand the wear of Ti6Al4V mated with 440F steel rollers. Misalignment angle was found to have the most significant effect on debris formation. At misalignment angle of 1.4deg, significant amount of wear debris were formed within 50,000 cycles. Very few wear particles were found for a zero misalignment angle, and the total wear was small even after 367,000 cycles. The mode of wear in all the tests was attributed to adhesion, which was clearly evident from video records as well as the plate-like amalgamated debris material from both rollers. The adhesive wear rate was found to be approximately proportional to the misalignment angle. The wear is a two-way phenomenon, and the mixing of both roller materials in wear debris was confirmed by x-ray fluorescence (XRF) and EDX spectra. While there was a net loss of mass from the steel rollers, XRF and energy dispersive x-ray (EDX) spectra showed peaks of Ti on steel rollers, and peaks of Fe on Ti rollers. These results are useful for designers in terms of maintaining appropriate tolerances to avoid misalignment of rolling elements and the resulting severe wear

  6. Global evaluation of erosion rates in relation to tectonics

    Science.gov (United States)

    Hecht, Hagar; Oguchi, Takashi

    2017-12-01

    Understanding the mechanisms and controlling factors of erosion rates is essential in order to sufficiently comprehend bigger processes such as landscape evolution. For decades, scientists have been researching erosion rates where one of the main objectives was to find the controlling factors. A variety of parameters have been suggested ranging from climate-related, basin morphometry and the tectonic setting of an area. This study focuses on the latter. We use previously published erosion rate data obtained mainly using 10Be and sediment yield and sediment yield data published by the United States Geological Survey. We correlate these data to tectonic-related factors, i.e., distance to tectonic plate boundary, peak ground acceleration ( PGA), and fault distribution. We also examine the relationship between erosion rate and mean basin slope and find significant correlations of erosion rates with distance to tectonic plate boundary, PGA, and slope. The data are binned into high, medium, and low values of each of these parameters and grouped in all combinations. We find that groups with a combination of high PGA (> 0.2.86 g) and long distance (> 1118.69 km) or low PGA (erosion rates include long distance and/or low PGA, and groups with high erosion rates include neither of these. These observations indicate that tectonics plays a major role in determining erosion rates, which is partly ascribable to steeper slopes produced by active crustal movements. However, our results show no apparent correlation of slope with erosion rates, pointing to problems with using mean basin-wide slope as a slope indicator because it does not represent the complex slope distribution within a basin.

  7. An Alternative Approach to Simulating an Entire Particle Erosion Experiment

    Directory of Open Access Journals (Sweden)

    Dirk Spaltmann

    2018-03-01

    Full Text Available Solid particle erosion affects many areas, such as dust or volcanic ash in areo-engines. The development of protective materials and surface engineering is costly and time consuming. A lot of effort has been placed into the advancement of models to speed up this process. Finite element or discrete element-based models are quite successful in predicting single or multiple impacts. However, they reach their limit if an entire erosion experiment is to be simulated. Therefore, in the present work, an approach is presented which combines various aspects of the former models with probability considerations. It is used to simulate the impact of more than one billion Alumina particles onto a steel substrate. This approach permits the simulation of an entire erosion experiment on an average PC (i5-2520M CPU@2.5 GHz processor, 4 GB main memory within about six hours. The respective predictions of wear scar and impact-mass/mass-loss curve are compared to the real experiment.

  8. Assessment of Pole Erosion in a Magnetically Shielded Hall Thruster

    Science.gov (United States)

    Mikellides, Ioannis G.; Ortega, Alejandro L.

    2014-01-01

    Numerical simulations of a 6-kW laboratory Hall thruster called H6 have been performed to quantify the erosion rate at the inner pole. The assessments have been made in two versions of the thruster, namely the unshielded (H6US) and magnetically shielded (H6MS) configurations. The simulations have been performed with the 2-D axisymmetric code Hall2De which employs a new multi-fluid ion algorithm to capture the presence of low-energy ions in the vicinity of the poles. It is found that the maximum computed erosion rate at the inner pole of the H6MS exceeds the measured rate of back-sputtered deposits by 4.5 times. This explains only part of the surface roughening that was observed after a 150-h wear test, which covered most of the pole area exposed to the plasma. For the majority of the pole surface the computed erosion rates are found to be below the back-sputter rate and comparable to those in the H6US which exhibited little to no sputtering in previous tests. Possible explanations for the discrepancy are discussed.

  9. Dental wear, wear rate, and dental disease in the African apes.

    Science.gov (United States)

    Elgart, Alison A

    2010-06-01

    The African apes possess thinner enamel than do other hominoids, and a certain amount of dentin exposure may be advantageous in the processing of tough diets eaten by Gorilla. Dental wear (attrition plus abrasion) that erodes the enamel exposes the underlying dentin and creates additional cutting edges at the dentin-enamel junction. Hypothetically, efficiency of food processing increases with junction formation until an optimal amount is reached, but excessive wear hinders efficient food processing and may lead to sickness, reduced fecundity, and death. Occlusal surfaces of molars and incisors in three populations each of Gorilla and Pan were videotaped and digitized. The quantity of incisal and molar occlusal dental wear and the lengths of dentin-enamel junctions were measured in 220 adult and 31 juvenile gorilla and chimpanzee skulls. Rates of dental wear were calculated in juveniles by scoring the degree of wear between adjacent molars M1 and M2. Differences were compared by principal (major) axis analysis. ANOVAs compared means of wear amounts. Pearson correlation coefficients were calculated to compare the relationship between molar wear and incidence of dental disease. Results indicate that quantities of wear are significantly greater in permanent incisors and molars and juvenile molars of gorillas compared to chimpanzees. The lengths of dentin-enamel junctions were predominantly suboptimal. Western lowland gorillas have the highest quantities of wear and the most molars with suboptimal wear. The highest rates of wear are seen in Pan paniscus and Pan t. troglodytes, and the lowest rates are found in P.t. schweinfurthii and G. g. graueri. Among gorillas, G. b. beringei have the highest rates but low amounts of wear. Coefficients between wear and dental disease were low, but significant when all teeth were combined. Gorilla teeth are durable, and wear does not lead to mechanical senescence in this sample.

  10. The prevalence of dental erosion in 5-year-old preschoolers in Sharjah, United Arab Emirates.

    Science.gov (United States)

    Gopinath, Vellore Kannan

    2016-01-01

    The aim of this study was to determine the percentage of 5-year-old preschoolers in Sharjah, affected by dental erosion and to assess the predictors. A total of 403 5-year-old children were examined of which 48.14% (n = 194) were boys and 51.86% (n = 209) were girls; 31.27% (n = 126) were Emirati and 68.73% (n = 277) were non-Emirati Arabs. Examination of dental erosion was confined to palatal surfaces of maxillary incisors using the erosion index described in the UK National Survey of Children's Dental Health, 1993. Dental caries was charted using the World Health Organization 1997 criteria. In the sample of 403 5-year-old preschoolers examined, dental erosion was apparent in 237 (58.80%) children, with 55.09% showing the dissolution of enamel and 3.72% exhibiting exposed dentin. Predictors of dental erosion as determined by logistic regression concluded that compared to Emirati citizens other Arab nationalities have 0.27 times the odds (95% confidence interval [CI] =0.18-0.42) of having tooth erosion (P erosion compared to children with no caries experience (P erosion compared to children who drink water (P erosion. Caries experience and consumption of acidic drinks were associated with dental erosion.

  11. Estimating soil erosion losses in Korea with fallout cesium-137

    International Nuclear Information System (INIS)

    Menzel, R.G.; Pilkyun Jung; Kwanshig Ryu; Kitai Um

    1987-01-01

    The contents of fallout 137 Cs in soil profiles were used to estimate erosion losses from steeply sloping croplands in Korea. Seven undisturbed sites with no apparent erosion or deposition, and 15 cropland sites were examined to a depth of 30 cm. The cropland sites had been cultivated for periods ranging from 5 to more than 80 y (median 10 y), and their slopes ranged from 5 to 26% (median 13%). All except one of the cropland sites contained less 137 Cs than undisturbed sites in the same area. Three cropland sites contained essentially no 137 Cs, indicating erosion of the entire cultivated layer of soil in from 6 to 10 years. Other cropland sites, particularly those with sandy texture, showed little loss of 137 Cs over longer periods of cultivation. Cesium-137 measurements may be useful in identifying site characteristics that reduce the vulnerability of sloping soils to erosion damage. (author)

  12. Design Mixers to Minimize Effects of Erosion and Corrosion Erosion

    Directory of Open Access Journals (Sweden)

    Julian Fasano

    2012-01-01

    Full Text Available A thorough review of the major parameters that affect solid-liquid slurry wear on impellers and techniques for minimizing wear is presented. These major parameters include (i chemical environment, (ii hardness of solids, (iii density of solids, (iv percent solids, (v shape of solids, (vi fluid regime (turbulent, transitional, or laminar, (vii hardness of the mixer's wetted parts, (viii hydraulic efficiency of the impeller (kinetic energy dissipation rates near the impeller blades, (ix impact velocity, and (x impact frequency. Techniques for minimizing the wear on impellers cover the choice of impeller, size and speed of the impeller, alloy selection, and surface coating or coverings. An example is provided as well as an assessment of the approximate life improvement.

  13. New perspectives on the soil erosion-soil quality relationship

    International Nuclear Information System (INIS)

    Pennock, D.J.

    1998-01-01

    The redistribution of soil has a profound impact on its quality (defined as its ability to function within its ecosystem and within adjacent ecosystems) and ultimately on its productivity for crop growth. The application of 137 Cs-redistribution techniques to the study of erosion has yielded major new insights into the soil erosion-soil quality relationship. In highly mechanized agricultural systems, tillage erosion can be the dominant cause of soil redistribution; in other agroecosystems, wind and water erosion dominate. Each causal factor results in characteristic landscape-scale patterns of redistribution. In landscapes dominated by tillage redistribution, highest losses occur in shoulder positions (those with convex downslope curvatures); in water-erosion-dominated landscapes, highest losses occur where slope gradient and length are at a maximum. Major impacts occur through the loss of organically-enriched surface material and through the incorporation of possibly yield-limiting subsoils into the rooting zone of the soil column. The potential impact of surface soil losses and concomitant subsoil incorporation on productivity may be assessed by examining the pedological nature of the affected soils and their position in the landscape. The development of sound conservation policies requires that the soil erosion-quality relationship be rigorously examined in the full range of pedogenic environments, and future applications of the 137 Cs technique hold considerable promise for providing this comprehensive global database. (author)

  14. Potential impacts of climate change on rainfall erosivity and water availability in China in the next 100 years

    Science.gov (United States)

    Ge Sun; Steven G. McNulty; Jennifer Moore; Corey Bunch; Jian Ni

    2002-01-01

    Soil erosion and water shortages threaten China’s social and economic development in the 21st century. This paper examines how projected climate change could affect soil erosion and water availability across China. We used both historical climate data (1961-1980) and the UKMO Hadley3 climate scenario (1960-2099) to drive regional hydrology and soil erosivity models....

  15. A Multidirectional Tribo-System: Wear of UHMWPE under Sliding, Rolling, and Rotation

    Science.gov (United States)

    Patten, Elias Wolfgang

    Total knee replacements (TKR) have become a successful surgical procedure for addressing end-stage osteoarthritis, with ultra-high molecular weight polyethylene and cobalt chrome alloy (UHMWPE/Co-Cr) serving as the bearing materials of choice for decades. However, more than 10% of TKRs fail and require revision surgery. The predominant challenge with UHMWPE is the particulate debris generated through wear-mediated processes; wear debris from the UHMWPE tibial bearing surface leading to loosening is still the main cause for post-fifth-year revisions. UHMWPE wear in hip arthroplasty has been linked to microstructural evolution at the surface from multidirectional sliding in the hip joint but little is known about how the microstructure responds to clinically relevant sliding conditions in the knee. This is likely because wear tests are typically performed under basic motion parameters with simplified geometry (pin-on-disk tests) while the knee has more complex kinematics: it is neither a ball-and-socket joint nor a simple hinge joint, but has 2D sliding, rolling/slip motion, and rotation. There is also disagreement over how to best quantify cross-shear and how to model how much wear it will cause. A custom multidirectional tribo-system was used to investigate the individual and combined effects of the different motions in TKR: 2D sliding, rolling, and rotation, for a total of eight separate kinematic conditions. The trends in wear rates and wear factors for these different motions were compared with many different definitions for magnitudes and ratios of cross-shear. Additionally, the wear surfaces were examined for wear mechanism and the microstructural changes in lamellae orientation for the different motions were analyzed. To mimic the tribological conditions of a condyle in a TKR, polished Co-Cr spheres were articulated against flat, smooth UHMWPE disks with physiologically relevant loading, speed, and lubrication conditions. The motion parameters were selected

  16. Compost for steep slope erosion.

    Science.gov (United States)

    2008-06-01

    This study was initiated to develop guidelines for maintenance erosion control measures for steep slopes. The study focused on evaluating and monitoring KY-31 fescue germination rates using two media treatments 1) 100 percent by weight compost and 2)...

  17. Erosion-resistant composite material

    Science.gov (United States)

    Finch, C.B.; Tennery, V.J.; Curlee, R.M.

    A highly erosion-resistant composite material is formed of chemical vapor-deposited titanium diboride on a sintered titanium diboride-nickel substrate. This material may be suitable for use in cutting tools, coal liquefaction systems, etc.

  18. Soil Erosion and Agricultural Sustainability

    Science.gov (United States)

    Montgomery, D. R.

    2009-04-01

    Data drawn from a global compilation of studies support the long articulated contention that erosion rates from conventionally plowed agricultural fields greatly exceed rates of soil production, erosion under native vegetation, and long-term geological erosion. Whereas data compiled from around the world show that soil erosion under conventional agriculture exceeds both rates of soil production and geological erosion rates by up to several orders of magnitude, similar global distributions of soil production and geological erosion rates suggest an approximate balance. Net soil erosion rates in conventionally plowed fields on the order of 1 mm/yr can erode typical hillslope soil profiles over centuries to millennia, time-scales comparable to the longevity of major civilizations. Well-documented episodes of soil loss associated with agricultural activities date back to the introduction of erosive agricultural methods in regions around the world, and stratigraphic records of accelerated anthropogenic soil erosion have been recovered from lake, fluvial, and colluvial stratigraphy, as well as truncation of soil stratigraphy (such as truncated A horizons). A broad convergence in the results from studies based on various approaches employed to study ancient soil loss and rates of downstream sedimentation implies that widespread soil loss has accompanied human agricultural intensification in examples drawn from around the world. While a broad range of factors, including climate variability and society-specific social and economic contexts — such as wars or colonial relationships — all naturally influence the longevity of human societies, the ongoing loss of topsoil inferred from studies of soil erosion rates in conventional agricultural systems has obvious long-term implications for agricultural sustainability. Consequently, modern agriculture — and therefore global society — faces a fundamental question over the upcoming centuries. Can an agricultural system

  19. Microstructure and wear resistance of in situ porous TiO/Cu composites

    Science.gov (United States)

    Qin, Qingdong; Huang, Bowei; Li, Wei

    2016-07-01

    An in situ porous TiO/Cu composite is successfully prepared using powder metallurgy by the reaction of Ti2CO and Cu powder. Morphological examination of the composite shows that the porosity of composites lies in the range between 10.2% and 35.2%. Dry sliding un-lubricated wear tests show that the wear resistance of the composite is higher than that of the Cu-Al alloy ingot. The coefficient of friction test shows that, as the volume fraction of the reinforced phase increases, the coefficient of friction decreases. The wear rate variation trend of the oil-lubricated wear test results is similar to that of the un-lubricated wear test results. The coefficient of friction for oil lubrication is similar for different volume fractions of the reinforced phase. The wear resistance of the composite at a sliding velocity of 200 rpm is slightly larger than that at 50 rpm. The porosity of the composites enhances the high-velocity oil-lubricated sliding wear resistance.

  20. Characterization of Erosion and Failure Processes of Spark Plugs After Field Service in Natural Gas Engines

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Hua-Tay [ORNL; Brady, Michael P [ORNL; Richards, Roger K [ORNL; Layton, David [National Transportation Research Center (NTRC)

    2005-01-01

    Microstructural and optical spectroscopic analyses were carried out on as-received and used spark plugs after field service in natural gas (NG) reciprocating engines. The objective of this work was to examine the corrosion and erosion mechanisms of natural gas engine spark plug as well as identify the primary life limiting processes during field operation. The optical emission spectroscopic analysis showed a strong Ca signal in the exposed spark plugs and scanning electron microscopy showed substantial formation of Ca-enriched glassy oxide phase(s) on the electrode surfaces. In addition, intergranular cracking was observed in the subsurface region of both iridium (Ir) and platinum-tungsten (Pt-W) alloy electrode insert tips. The coalescence and subsequent growth of these cracks would accelerate the wear of the electrodes and shorten the lifetime of the spark plugs. Also, extensive internal oxidation and subsequent crack generation occurred along the interface between Ni-base alloy electrode and Pt-W alloy tip insert during field service, which would result in substantial degradation in the ignitability and performance of the electrodes, and thus spark plug failure.

  1. Wear Characteristics of Metallic Biomaterials: A Review

    Directory of Open Access Journals (Sweden)

    Mohamed A. Hussein

    2015-05-01

    Full Text Available Metals are extensively used in a variety of applications in the medical field for internal support and biological tissue replacements, such as joint replacements, dental roots, orthopedic fixation, and stents. The metals and alloys that are primarily used in biomedical applications are stainless steels, Co alloys, and Ti alloys. The service period of a metallic biomaterial is determined by its abrasion and wear resistance. A reduction in the wear resistance of the implant results in the release of incompatible metal ions into the body that loosen the implant. In addition, several reactions may occur because of the deposition of wear debris in tissue. Therefore, developing biomaterials with high wear resistance is critical to ensuring a long life for the biomaterial. The aim of this work is to review the current state of knowledge of the wear of metallic biomaterials and how wear is affected by the material properties and conditions in terms of the type of alloys developed and fabrication processes. We also present a brief evaluation of various experimental test techniques and wear characterization techniques that are used to determine the tribological performance of metallic biomaterials.

  2. Investigation of erosion behavior in different pipe-fitting using Eulerian-Lagrangian approach

    Science.gov (United States)

    Kulkarni, Harshwardhan; Khadamkar, Hrushikesh; Mathpati, Channamallikarjun

    2017-11-01

    Erosion is a wear mechanism of piping system in which wall thinning occurs because of turbulent flow along with along with impact of solid particle on the pipe wall, because of this pipe ruptures causes costly repair of plant and personal injuries. In this study two way coupled Eulerian-Lagrangian approach is used to solve the liquid solid (water-ferrous suspension) flow in the different pipe fitting namely elbow, t-junction, reducer, orifice and 50% open gate valve. Simulations carried out using incomressible transient solver in OpenFOAM for different Reynolds's number (10k, 25k, 50k) and using WenYu drag model to find out possible higher erosion region in pipe fitting. Used transient solver is a hybrid in nature which is combination of Lagrangian library and pimpleFoam. Result obtained from simulation shows that exit region of elbow specially downstream of straight, extradose of the bend section more affected by erosion. Centrifugal force on solid particle at bend affect the erosion behavior. In case of t-junction erosion occurs below the locus of the projection of branch pipe on the wall. For the case of reducer, orifice and a gate valve reduction area as well as downstream is getting more affected by erosion because of increase in velocities.

  3. Wear mechanism and wear prevention in coal-fueled diesel engines. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Schwalb, J.A.; Ryan, T.W.

    1991-10-01

    Coal fueled diesel engines present unique wear problems in the piston ring/cylinder liner area because of their tendency to contaminate the lube-oil with high concentrations of highly abrasive particles. This program involved a series of bench-scale wear tests and engine tests designed to investigate various aspects of the ring/liner wear problem and to make specific recommendations to engine manufacturers as to how to alleviate these problems. The program was organized into tasks, designed to accomplish the following objectives: (1) define the predominant wear mechanisms causing accelerated wear in the ring/liner area; (2) investigate the effectiveness of traditional approaches to wear prevention to prevent wear in coal-fueled engines; (3) further refine information on the most promising approaches to wear prevention; (4) present detailed information and recommendations to engine manufacturers on the most promising approach to wear prevention; (5) present a final report covering the entire program; (6)complete engine tests with a coal-derived liquid fuel, and investigate the effects of the fuel on engine wear and emissions.

  4. Wear mechanism and wear prevention in coal-fueled diesel engines

    Energy Technology Data Exchange (ETDEWEB)

    Schwalb, J.A.; Ryan, T.W.

    1991-10-01

    Coal fueled diesel engines present unique wear problems in the piston ring/cylinder liner area because of their tendency to contaminate the lube-oil with high concentrations of highly abrasive particles. This program involved a series of bench-scale wear tests and engine tests designed to investigate various aspects of the ring/liner wear problem and to make specific recommendations to engine manufacturers as to how to alleviate these problems. The program was organized into tasks, designed to accomplish the following objectives: (1) define the predominant wear mechanisms causing accelerated wear in the ring/liner area; (2) investigate the effectiveness of traditional approaches to wear prevention to prevent wear in coal-fueled engines; (3) further refine information on the most promising approaches to wear prevention; (4) present detailed information and recommendations to engine manufacturers on the most promising approach to wear prevention; (5) present a final report covering the entire program; (6)complete engine tests with a coal-derived liquid fuel, and investigate the effects of the fuel on engine wear and emissions.

  5. Effects of chemistry on corrosion-erosion of steels in water and wet steam

    International Nuclear Information System (INIS)

    Berge, P.; Ducreux, J.; Saint-Paul, P.

    1981-01-01

    In steam production plants, numerous cases of degradation of steels occur when in contact with water or wet steam circulating at high velocity: in feed or discharge pumps, water reheaters, etc. When the phenomenon occurs without any mechanical wear of the metal or the oxide from the impact of solid particles (abrasion) or droplets (erosion), it is called corrosion-erosion. The phenomenon usually occurs between 100 and 250 0 C, as has been confirmed by an empirical study of the thermal and hydraulic factors which govern it. Corrosion rates can reach 1 to 2 mm/year, for a carbon steel pipe where water treated with ammonia circulates at about pH 9, at 200 0 C, and at a velocity of 5 to 10 m/s. This study evaluates the part played by the factors solely connected to the chemistry of water, with respect to the kinetics of the corrosion-erosion phenomenon. (author)

  6. Wind erosion of soils burned by wildfire

    Science.gov (United States)

    N. S. Wagenbrenner; M. J. Germino; B. K. Lamb; R. B. Foltz; P. R. Robichaud

    2011-01-01

    Wind erosion and aeolian transport processes are largely unstudied in the post-wildfire environment, but recent studies have shown that wind erosion can play a major role in burned landscapes. A wind erosion monitoring system was installed immediately following a wildfire in southeastern Idaho, USA to measure wind erosion from the burned area (Figure 1). This paper...

  7. Gaussian process regression for tool wear prediction

    Science.gov (United States)

    Kong, Dongdong; Chen, Yongjie; Li, Ning

    2018-05-01

    To realize and accelerate the pace of intelligent manufacturing, this paper presents a novel tool wear assessment technique based on the integrated radial basis function based kernel principal component analysis (KPCA_IRBF) and Gaussian process regression (GPR) for real-timely and accurately monitoring the in-process tool wear parameters (flank wear width). The KPCA_IRBF is a kind of new nonlinear dimension-increment technique and firstly proposed for feature fusion. The tool wear predictive value and the corresponding confidence interval are both provided by utilizing the GPR model. Besides, GPR performs better than artificial neural networks (ANN) and support vector machines (SVM) in prediction accuracy since the Gaussian noises can be modeled quantitatively in the GPR model. However, the existence of noises will affect the stability of the confidence interval seriously. In this work, the proposed KPCA_IRBF technique helps to remove the noises and weaken its negative effects so as to make the confidence interval compressed greatly and more smoothed, which is conducive for monitoring the tool wear accurately. Moreover, the selection of kernel parameter in KPCA_IRBF can be easily carried out in a much larger selectable region in comparison with the conventional KPCA_RBF technique, which helps to improve the efficiency of model construction. Ten sets of cutting tests are conducted to validate the effectiveness of the presented tool wear assessment technique. The experimental results show that the in-process flank wear width of tool inserts can be monitored accurately by utilizing the presented tool wear assessment technique which is robust under a variety of cutting conditions. This study lays the foundation for tool wear monitoring in real industrial settings.

  8. Minimization of PWR reactor control rods wear

    International Nuclear Information System (INIS)

    Ponzoni Filho, Pedro; Moura Angelkorte, Gunther de

    1995-01-01

    The Rod Cluster Control Assemblies (RCCA's) of Pressurized Water Reactors (PWR's) have experienced a continuously wall cladding wear when Reactor Coolant Pumps (RCP's) are running. Fretting wear is a result of vibrational contact between RCCA rodlets and the guide cards which provide lateral support for the rodlets when RCCA's are withdrawn from the core. A procedure is developed to minimize the rodlets wear, by the shuffling and axial reposition of RCCA's every operating cycle. These shuffling and repositions are based on measurement of the rodlet cladding thickness of all RCCA's. (author). 3 refs, 2 figs, 2 tabs

  9. Physical and Constructive (Limiting) Criterions of Gear Wheels Wear

    Science.gov (United States)

    Fedorov, S. V.

    2018-01-01

    We suggest using a generalized model of friction - the model of elastic-plastic deformation of the body element, which is located on the surface of the friction pairs. This model is based on our new engineering approach to the problem of friction-triboergodynamics. Friction is examined as transformative and dissipative process. Structural-energetic interpretation of friction as a process of elasto-plastic deformation and fracture contact volumes is proposed. The model of Hertzian (heavy-loaded) friction contact evolution is considered. The least wear particle principle is formulated. It is mechanical (nano) quantum. Mechanical quantum represents the least structural form of solid material body in conditions of friction. It is dynamic oscillator of dissipative friction structure and it can be examined as the elementary nanostructure of metal’s solid body. At friction in state of most complete evolution of elementary tribosystem (tribocontact) all mechanical quanta (subtribosystems) with the exception of one, elasticity and reversibly transform energy of outer impact (mechanic movement). In these terms only one mechanical quantum is the lost – standard of wear. From this position we can consider the physical criterion of wear and the constructive (limiting) criterion of gear teeth and other practical examples of tribosystems efficiency with new tribology notion – mechanical (nano) quantum.

  10. The effect of the longshore dimension on dune erosion

    NARCIS (Netherlands)

    Van Thiel de Vries, J.S.M.; Van Dongeren, A.R.; McCall, R.; Reniers, A.

    2011-01-01

    The effect of the longshore dimension on dune erosion is examined numerically with a 2DH process based model XBeach. Exploratory simulations are presented to examine longshore effects due to directionally spread waves, longshore variation in topography and longshore variation in bathymetry. The

  11. Erosion and deposition of metals and carbon in the DIII-D divertor

    International Nuclear Information System (INIS)

    Wampler, W.R.; Bastasz, R.; Buchenauer, D.

    1995-01-01

    Net erosion rates at the outer strike point of the DIII-D divertor plasma were measured for several materials during quiescent H-mode operation with deuterium plasmas. Materials examined include graphite, beryllium, tungsten, vanadium and molybdenum. For graphite, net erosion rates up to 4 nm/sec were found. Erosion rates for the metals were much smaller than for carbon. Ion fluxes from Langmuir probe measurements were used to predict gross erosion by sputtering. Measured net erosion was much smaller than predicted gross erosion. Transport of metal atoms by the plasma across the divertor surface was also examined. Light atoms were transported farther than heavy atoms as predicted by impurity transport models

  12. Effect of erodent particles on the erosion of metal specimens

    Energy Technology Data Exchange (ETDEWEB)

    Razzaque, M. Mahbubur, E-mail: mmrazzaque@me.buet.ac.bd; Alam, M. Khorshed; Khan, M. Ishak, E-mail: ishak.buet@gmail.com [Department of Mechanical Engineering Bangladesh University of Engineering and Technology (BUET), Dhaka (Bangladesh)

    2016-07-12

    This paper presents the experimental results of the measurement of erosion rate of carbon steel specimens in sand water slurry system in a slurry pot tester. Sylhet sand has been sieved to get three sizes of erodent particles; namely, less than 250 micron, 250 to 590 micron and 590 to 1190 micron. Experiments are done with three sand concentrations (10%, 15% and 20%). The rate of erosion of the carbon steel specimens is measured as the loss of weight per unit surface area per unit time under the dynamic action of solid particles. The eroded surfaces of the specimens are examined using Scanning Electron Microscopy (SEM) to visualize the impact of the slurry of various conditions. It is seen that irrespective of the particle size the rate of erosion increases with the increase of slurry concentration. This increment of erosion rate at high concentration is high for large particles. High erosion rate is observed in case of large sand particles. In case of small and fine particles erosion rate is small because of low impact energy as well as the wastage of energy to overcome the hindrance of the finer particles before striking on the specimen surface.

  13. Effect of erodent particles on the erosion of metal specimens

    Science.gov (United States)

    Razzaque, M. Mahbubur; Alam, M. Khorshed; Khan, M. Ishak

    2016-07-01

    This paper presents the experimental results of the measurement of erosion rate of carbon steel specimens in sand water slurry system in a slurry pot tester. Sylhet sand has been sieved to get three sizes of erodent particles; namely, less than 250 micron, 250 to 590 micron and 590 to 1190 micron. Experiments are done with three sand concentrations (10%, 15% and 20%). The rate of erosion of the carbon steel specimens is measured as the loss of weight per unit surface area per unit time under the dynamic action of solid particles. The eroded surfaces of the specimens are examined using Scanning Electron Microscopy (SEM) to visualize the impact of the slurry of various conditions. It is seen that irrespective of the particle size the rate of erosion increases with the increase of slurry concentration. This increment of erosion rate at high concentration is high for large particles. High erosion rate is observed in case of large sand particles. In case of small and fine particles erosion rate is small because of low impact energy as well as the wastage of energy to overcome the hindrance of the finer particles before striking on the specimen surface.

  14. STUDIES ON TOOL WEAR CONDITION MONITORING

    Directory of Open Access Journals (Sweden)

    Hüseyin Metin ERTUNÇ

    2001-01-01

    Full Text Available In this study, wear mechanisms on cutting tools, especially for the drill bits, during the cutting operation have been investigated. As the importance of full automation in industry has gained substantial importance, tool wear condition monitoring during the cutting operation has been the subject of many investigators. Tool condition monitoring is very crucial in order to change the tool before breakage. Because tool breakage can cause considerable economical damage to both the machine tool and workpiece. In this paper, the studies on the monitoring of drill bit wear in literature have been introduced; the direct/indirect techniques used and sensor fusion techniques have been summarized. The methods which were proposed to determine tool wear evolution as processing the sensor signals collected have been provided and their references have been given for detailed information.

  15. Evaluation of the working clothes for nuclear power stations in wearing

    International Nuclear Information System (INIS)

    Sasaki, Kazumi

    1984-01-01

    For the working clothes used for nuclear power stations, i.e. coveralls, Tyvek (nonwoven-fabric) clothings generally worn on coveralls to prevent dust and contaminant, and PVC suits, in order to improve the properties in wearing respective clothes, the following characteristics were examined when persons actually wear them: clothing weather, physiological phenomena and conscious complaints. The PVC suits with large steam resistance are not desirable at a temperature in working environment exceeding 30 deg C; but in the environment at 20 deg C and 30 deg C, the influence by thermal load is little. By judging from a thermal environment index, there was no difference in wearing the coveralls and the Tyvek clothings; even if wearing Tyvek clothings on coveralls, the influence is little. Considering the physiological limit of workers, however, the working environment where the allowable levels of heart beat, perspiration quantity and skin temperature are not exceeded is desirable. (Mori, K.)

  16. Effect of Reduced Graphene Oxide Reinforcement on the Wear Characteristics of Electroless Ni-P Coatings

    Science.gov (United States)

    Tamilarasan, T. R.; Sanjith, U.; Rajendran, R.; Rajagopal, G.; Sudagar, J.

    2018-03-01

    Electroless composite coatings with various concentrations of reduced graphene oxide (rGO) particles were deposited onto mild steel substrate. The effects of adding rGO particles by varying their concentration from 0 to 100 mg/L on morphology, composition, microhardness, adhesion, wear and friction of the electroless composite coatings were investigated. Among the various parameters that influence the tribological behavior, sliding velocity was varied within a specific range for definite concentrations of rGO to obtain enhanced wear resistance in this study. The micrographs of the worn surfaces and indented spots were examined for the nature of wear mechanism and interfacial adhesion. The wear rate increased with increasing sliding velocity but was relatively stable for coatings with lower concentrations of rGO.

  17. Physiological responses to simulated stair climbing in professional firefighters wearing rubber and leather boots.

    Science.gov (United States)

    Huang, Chun-Jung; Garten, Ryan S; Wade, Chip; Webb, Heather E; Acevedo, Edmund O

    2009-09-01

    No studies have considered whether a firefighter's boots are a factor influencing physiological responses. The purpose of this study was to examine physiological responses to a fire simulation activity (stair climb) in professional firefighters wearing rubber boots (RB) and leather boots (LB). Twelve professional firefighters participated in two counterbalanced simulated firefighter stair climb (SFSC) sessions, one wearing RB and the other wearing LB. Heart rate, oxygen uptake (VO(2)), expiratory ventilation (V(E)), blood lactate (BLa), salivary cortisol (SCORT), and leg strength were assessed prior to and following a SFSC. LB elicited significantly greater SCORT values and knee flexion time to peak torque. Furthermore, RB revealed significantly greater ankle dorsiflexion peak torque after SFSC. BLa was positively related to knee flexion peak torque after SFSC in the RB. Firefighters when wearing the RB may be more effective at resisting fatigue and increase more force production.

  18. Third abrasive wear mode: is it possible?

    Directory of Open Access Journals (Sweden)

    Ronaldo Câmara Cozza

    2014-04-01

    Full Text Available The objective of this paper is to propose an initial discussion on the characterization of a third abrasive wear mode. The results obtained in a previous work [1] under different test conditions revealed the occurrence of the superposition of the “rolling” and “grooving” abrasive wear modes. This phenomenon was denoted “micro-rolling abrasion” due to the observation that “rolling abrasion” was found to act on “grooving abrasion”.

  19. Biocompatible wear-resistant thick ceramic coating

    Directory of Open Access Journals (Sweden)

    Vogt Nicola

    2016-09-01

    Full Text Available Sensitisation to immunologically active elements like chromium, cobalt or nickel and debris particle due to wear are serious problems for patients with metallic implants. We tested the approach of using a hard and thick ceramic coating as a wear-resistant protection of titanium implants, avoiding those sensitisation and foreign body problems. We showed that the process parameters strongly influence the coating porosity and, as a consequence, also its hardness.

  20. Development and Performance Evaluation of an Abrasive Wear ...

    African Journals Online (AJOL)

    The wear of tillage tools is a major source of economic constraints to local farmers. Estimating wear in the field is time consuming and expensive. Abrasive wear testing machines developed in advanced countries are not available in Ghana. This makes the study of wear related problems at laboratory levels difficult in the ...

  1. Assessing Wear of the Acetabular Cup Using Computed Tomography: an ex vivo Study

    International Nuclear Information System (INIS)

    Olivecrona, L.; Jedenmalm, A.; Aspelin, P.; Weidenhielm, L.; Noz, M.E.; Maguire, G.Q.; Zeleznik, M.P.; Olivecrona, H.

    2005-01-01

    Purpose: To validate a clinically useful method for measuring acetabular cup wear using computed tomography (CT). Material and Methods: Eight uncemented acetabular cups were scanned twice ex vivo using CT. The linear penetration depth of the femoral component head into the cup and the thickness of the remaining polyethylene liner were measured in the CT volumes using dedicated software. Two independent examiners twice assessed each volume. The CT measurements were compared to direct measurements using a coordinate measuring device and micrometer measurements. Results: Accuracy of wear measurements expressed as penetration depth was ±0.6 and ±1.0 mm for the two examiners, respectively, with no significant differences between examiners, trials, and CT scans. Accuracy of measurements of remaining polyethylene was ±1.3 and ±1.0 mm, respectively, for the two examiners. Systematic differences between examiners were found, but no significant differences between trials and CT scans. These differences were due to different interpretations of metal artifacts in the volumes. Conclusion: The proposed CT method for evaluating wear as head penetration depth allows for reliable wear detection at a clinically relevant level. Measurements of remaining polyethylene on CT volumes are not as reliable as wear measurements owing to metal artifacts

  2. Pipe and bend erosion by pneumatic transport of solids at high temperature: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Klinzing, G. E.; Borzone, L. A.; Yang, Wen-Ching

    1989-06-01

    The erosion of various components of a pneumatic transport line has been studied through basic experiments, commercial-scale test runs and computer simulation. The main objective was to study the effect of the operating variables on the erosion rates of refractory lined straight sections and bends. Temperatures ranging from 22 to 830/degree/C, gas velocities from 12.9 to 34 m/s and solid flow rates from 48 to 225 kg/h were tested in a High Temperature Pneumatic Transport Test Facility. Four kinds of refractory concretes were used as targets. The erodent materials were river sand, coal slag and alumina. The effect of gas velocity and solids slow rate on the erosion rate was correlated in terms of power laws, while temperature effects proved to be more complex, since mechanical properties of both erodent and target materials change with temperature. The erosion of circular bends was evaluated using a computer model that combines computational particle dynamics and experimental data to predict the erosion pattern inside the bend. Experiments on the erosion of wedge samples, performed in the erosion test facility, and data on particle-wall collisions, obtained with the help of high-speed photographic techniques, were the basic set of data used in the simulation. As an alternative to circular radius bends, and experimental study of wear and flow patterns in blinded T-bends was performed. The internal geometry in this kind of bends was determined by the solids deposition, and complex erosion patterns appeared as the operating variables were manipulated. 81 figs., 50 tabs.

  3. Progress in Effect of Nano-modified Coatings and Welding Process Parameters on Wear of Contact Tube for Non-copper Coated Solid Wires

    Directory of Open Access Journals (Sweden)

    LI Zhuo-xin

    2017-12-01

    Full Text Available Environment-friendly non-copper coated solid wire is the main developing trend for gas shielded solid wires, whereas wear of contact tube limits their wide application. The effect of nano-modified coatings and welding process parameters on wear of contact tube for non-copper coated solid wires was reviewed. It was found that the wear of contact tube can be reduced due to the formation of tribo-films on the rubbing surfaces of welding wires against contact tube; it is feasible to decrease contact tube wear when non-copper coated solid wires are coated with nano-modified lubricants, thereby displaying excellent lubricating and thermal or electrical conduction characteristics. The wear of contact tube increases with the increase of welding current. The wear of contact tube is worse in direct-current electrode positive (DCEP than in direct-current electrode negative (DCEN. Arc ablation and electrical erosion are the dominant wear mechanisms of contact tube.

  4. Bentonite erosion - Laboratory studies

    International Nuclear Information System (INIS)

    Jansson, Mats

    2010-01-01

    Document available in extended abstract form only. Bentonite clay is proposed as buffer material in the KBS-3 concept of storing spent nuclear fuel. Since the clay is plastic it will protect the canisters containing the spent fuel from movements in the rock. Furthermore, the clay will expand when taking up water, become very compact and hence limit the transport of solutes to and from the canister to only diffusion. The chemical stability of the bentonite barrier is of vital importance. If much material would be lost the barrier will lose its functions. As a side effect, lots of colloids will be released which may facilitate radionuclide transport in case of a breach in the canister. There are scenarios where during an ice age fresh melt water may penetrate down to repository depths with relatively high flow rates and not mix with older waters of high salinity. Under such conditions bentonite colloids will be more stable and there is a possibility that the bentonite buffer would start to disperse and bentonite colloids be carried away by the passing water. This work is a part of a larger project called Bentonite Erosion, initiated and supported by SKB. In this work several minor experiments have been performed in order to investigate the influence of for instance di-valent cations, gravity, etc. on the dispersion behaviour of bentonite and/or montmorillonite. A bigger experiment where the real situation was simulated using an artificial fracture was conducted. Two Plexiglas slabs were placed on top of each other, separated by plastic spacers. Bentonite was placed in a container in contact with a fracture. The bentonite was water saturated before deionized water was pumped through the fracture. The evolution of the bentonite profile in the fracture was followed visually. The eluate was collected in five different slots at the outlet side and analyzed for colloid concentration employing Photon Correlation Spectroscopy (PCS) and a Single Particle Counter (SPC). Some

  5. Bentonite erosion. Laboratory studies

    Energy Technology Data Exchange (ETDEWEB)

    Jansson, Mats (Div. of Nuclear Chemistry, Royal Inst. of Technology, Stockholm (Sweden), School of Chemical Science and Engineering)

    2009-11-15

    This report covers the laboratory studies that have been performed at Nuclear Chemistry, KTH in the project 'Bentonite Erosion'. Many of the experiments in this report were performed to support the work of the modelling group and were often relatively simple. One of the experiment series was performed to see the impact of gravity and concentration of mono- and di-valent cations. A clay suspension was prepared in a test tube. A net was placed in contact with the suspension, the test tube was filled with solutions of different concentrations and the system was left overnight to settle. The tube was then turned upside down and the behaviour was visually observed. Either the clay suspension fell through the net or stayed on top. By using this method surprisingly sharp determinations of the Critical Coagulation (Flocculation) Concentration (CCC/CFC) could be made. The CCC/CFC of Ca2+ was for sodium montmorillonite determined to be between 1 and 2 mM. An artificial fracture was manufactured in order to simulate the real case scenario. The set-up was two Plexiglas slabs separated by 1 mm thick spacers with a bentonite container at one side of the fracture. Water was pumped with a very low flow rate perpendicular to bentonite container and the water exiting the fracture was sampled and analyzed for colloid content. The bentonite used was treated in different ways. In the first experiment a relatively montmorillonite rich clay was used while in the second bentonite where only the readily soluble minerals had been removed was used. Since Plexiglas was used it was possible to visually observe the bentonite dispersing into the fracture. After the compacted bentonite (1,000 kg/m3) had been water saturated the clay had expanded some 12 mm out into the fracture. As the experiment progressed the clay expanded more out into the fracture and seemed to fractionate in two different phases with less material in the outmost phase. A dark rim which was later analyzed to contain

  6. Using rare earth element tracers and neutron activation analysis to study rill erosion process

    International Nuclear Information System (INIS)

    Li Mian; Li Zhanbin; Ding Wengfeng; Liu Puling; Yao Wenyi

    2006-01-01

    Spatially averaged soil erosion data provide little information on the process of rill erosion. The dynamically varied data on the temporal and spatial distributions in the rill erosion process are needed to better understand the erosion process and reveal its innate characteristics. The objectives of this study were to examine the feasibility and effectiveness of rare earth element (REE) tracers and the neutron activation analysis (NAA) method on the study of the rill erosion process and to reveal quantitatively the relationships and characteristics of temporal and spatial distributions of sediment yield in rill erosion. Four REEs were used to study the changeable process of rill erosion at 4 slope positions. Four water inflow rates were applied to a 0.3x5 m soil bed at 3 slopes of 10.5%, 15.8% and 21.2% in scouring experiments. All of the runoff was collected in the experiment. Each sample was air-dried and well mixed. Then 20 g of each sample was sieved through 100-mesh and about a 50 mg sample was weighed for analysis of the four elemental compositions by NAA. Results indicate that the REE tracers and NAA method can be used to not only quantitatively determine soil erosion amounts on different slope segments, but also to reveal the changeable process of rill erosion amount. All of the relative errors of the experimental results were less than 25%, which is considered satisfactory on the study of rill erosion process

  7. Relationship between sports drinks and dental erosion in 304 university athletes in Columbus, Ohio, USA.

    Science.gov (United States)

    Mathew, Tanya; Casamassimo, Paul S; Hayes, John R

    2002-01-01

    Acidic soft drinks, including sports drinks, have been implicated in dental erosion with limited supporting data in scarce erosion studies worldwide. The purpose of this study was to determine the prevalence of dental erosion in a sample of athletes at a large Midwestern state university in the USA, and to evaluate whether regular consumption of sports drinks was associated with dental erosion. A cross-sectional, observational study was done using a convenience sample of 304 athletes, selected irrespective of sports drinks usage. The Lussi Index was used in a blinded clinical examination to grade the frequency and severity of erosion of all tooth surfaces excluding third molars and incisal surfaces of anterior teeth. A self-administered questionnaire was used to gather details on sports drink usage, lifestyle, health problems, dietary and oral health habits. Intraoral color slides were taken of all teeth with erosion. Sports drinks usage was found in 91.8% athletes and the total prevalence of erosion was 36.5%. Nonparametric tests and stepwise regression analysis using history variables showed no association between dental erosion and the use of sports drinks, quantity and frequency of consumption, years of usage and nonsport usage of sports drinks. The most significant predictor of erosion was found to be not belonging to the African race (p sports drinks and dental erosion. Copyright 2002 S. Karger AG, Basel

  8. Prevalence of dental erosion in 12-year-old schoolchildren of Lucknow city

    Directory of Open Access Journals (Sweden)

    Pooja Sinha

    2016-01-01

    Full Text Available Introduction: Dental erosion is tooth surface loss caused by chemical processes without bacterial involvement, which can affect children because of various dietary and other lifestyle factors. Aims: The aim of this study was to assess the prevalence of dental erosion in 12-year-old schoolchildren in Lucknow city. Materials and Methods: A total of 212 schoolchildren were selected through multistage cluster random sampling method. A pretested self-administered pro forma was used to record demographic data, medical history, and dietary habits. The clinical examination was done to evaluate dental erosion of children using dental erosion index by O'Sullivan. Descriptive analytical tests were used including distribution of erosion, its extent and severity. The findings were compared across the study participants using Chi-square test. Results: The overall prevalence of dental erosion was 34.12% with no significant sex difference. Dental erosion was significantly related to the frequency of consumption of fruit juices (67.07% followed by carbonated drinks (64.47%. In most of the cases, more than half of their surfaces were diagnosed as affected by erosion (26.25% central incisors, 4.83% lateral incisors. Conclusions: Dental erosion among the study group was found to be 34.12%, providing evidence that dental erosion is becoming a significant problem in Lucknow schoolchildren.

  9. Soil erosion in Slovene Istria

    Directory of Open Access Journals (Sweden)

    Matjaž Mikoš

    2009-12-01

    Full Text Available From the end of nineties of the 20th century, intense hydrologic and geomorphologic research is taking place in the Slovene Istria. As a part of this research also studies on soil erosion were undertaken in the period from 2005 to 2008. The field measurements were under taken onclosed 1m2 large erosion plots under three different land uses (on bare soils in an olive grove, on an overgrown meadow, in a forest, placed south of the Marezige village in the Rokava River basin.We show weekly measurements of surface erosion (interrill erosion for the period of 13 months (the end of March 2005 – the end of April 2006, as well as monthly and seasonal averages together with selected linear statistical correlations between soil erosion and weather parameters.From May 2005 to April 2006 the interrill erosion on bare soils in an olive grove with an inclination of 5.5° amounted to 9013 g/m2 (90 t/ha that corresponds to surface lowering rate of 8.5 mm/yr; on an overgrown meadow with an inclination of 9.4° it amounted to 168 g/m2 (1,68 t/ha that corresponds to surface lowering rate of 0.16 mm//yr; and in a forest with an inclination of 7.8° it amounted to 391 g/m2 (3,91 t/ha and in a forest with an inclination of 21.4° it amounted to 415 g/m2 (4,15 t/ha, respectively, that corresponds to surface lowering rate of 0.4 mm/yr.

  10. Wear-resistance of Aluminum Matrix Microcomposite Materials

    Directory of Open Access Journals (Sweden)

    M. Kandeva

    2011-03-01

    Full Text Available A procedure is developed for the study of wear of aluminum alloys AlSi7 obtained by casting, reinforced by TiC microparticles, before and after heat treatment. Tribological study is realized under conditions of friction on counterbody with fixed abrasive. Experimental results were obtained for mass wear, wear rate, wear intensity and wear-resistance of the alloys with different wt% of microparticles.

  11. Wear monitoring of single point cutting tool using acoustic emission ...

    Indian Academy of Sciences (India)

    It clearly indicates that the three stages of wear viz., Stage I, where the rate of wear is low, Stage II, where the rate of wear is moderate and. Stage III, where the rate of wear is faster and leading to the termination of tool life. In stage I, 0 to 8.5 min of the machining operation the tool wear is in the range of 0–8.3 μm only.

  12. A study of the effect of solid particle impact and particle shape on the erosion morphology of ductile metals

    Science.gov (United States)

    Rao, P. V.; Young, S. G.; Buckley, D. H.

    1984-01-01

    Impulsive versus steady jet impingement of spherical glass bead particles on metal surfaces was studied using a gas gun facility and a commercial sand blasting apparatus. Crushed glass particles were also used in the sand blasting apparatus as well as glass beads. Comparisons of the different types of erosion patterns were made. Scanning electron microscopy, surface profilometry and energy dispersive X-ray spectroscopy analysis were used to characterize erosion patterns. The nature of the wear can be divided into cutting and deformation, each with its own characteristic features. Surface chemistry analysis indicates the possiblity of complex chemical and/or mechanical interactions between erodants and target materials.

  13. A study of the nature of solid particle impact and shape on the erosion morphology of ductile metals

    Science.gov (United States)

    Rao, P. V.; Young, S. G.; Buckley, D. H.

    1982-01-01

    Impulsive versus steady jet impingement of spherical glass bead particles on metal surfaces was studied using a gas gun facility and a commercial sand blasting apparatus. Crushed glass particles were also used in the sand blasting apparatus as well as glass beads. Comparisons of the different types of erosion patterns were made. Scanning electron microscopy, surface profilometry and energy dispersive X-ray spectroscopy analysis were used to characterize erosion patterns. The nature of the wear can be divided into cutting and deformation, each with its own characteristic features. Surface chemistry analysis indicates the possibility of complex chemical and/or mechanical interactions between erodants and target materials.

  14. Rainfall erosivity in Central Chile

    Science.gov (United States)

    Bonilla, Carlos A.; Vidal, Karim L.

    2011-11-01

    SummaryOne of the most widely used indicators of potential water erosion risk is the rainfall-runoff erosivity factor ( R) of the Revised Universal Soil Loss Equation (RUSLE). R is traditionally determined by calculating a long-term average of the annual sum of the product of a storm's kinetic energy ( E) and its maximum 30-min intensity ( I30), known as the EI30. The original method used to calculate EI30 requires pluviograph records for at most 30-min time intervals. Such high resolution data is difficult to obtain in many parts of the world, and processing it is laborious and time-consuming. In Chile, even though there is a well-distributed rain gauge network, there is no systematic characterization of the territory in terms of rainfall erosivity. This study presents a rainfall erosivity map for most of the cultivated land in the country. R values were calculated by the prescribed method for 16 stations with continuous graphical record rain gauges in Central Chile. The stations were distributed along 800 km (north-south), and spanned a precipitation gradient of 140-2200 mm yr -1. More than 270 years of data were used, and 5400 storms were analyzed. Additionally, 241 spatially distributed R values were generated by using an empirical procedure based on annual rainfall. Point estimates generated by both methods were interpolated by using kriging to create a map of rainfall erosivity for Central Chile. The results show that the empirical procedure used in this study predicted the annual rainfall erosivity well (model efficiency = 0.88). Also, an increment in the rainfall erosivities was found as a result of the rainfall depths, a regional feature determined by elevation and increasing with latitude from north to south. R values in the study area range from 90 MJ mm ha -1 h -1 yr -1 in the north up to 7375 MJ mm ha -1 h -1 yr -1 in the southern area, at the foothills of the Andes Mountains. Although the map and the estimates could be improved in the future by

  15. Analysis of impact-sliding wear property of aluminum bronze against titanium alloy and 2Cr13 steel

    Science.gov (United States)

    Wei, Yongqiang; Wang, Liqin

    2009-07-01

    Impact-sliding wear of aluminum bronze against titanium alloy and 2Cr13 steel have been conducted using impactsliding wear test rig which was developed independently. Some non-destructive examinations have been performed on worn specimens, using weighing, 2D and 3D profilometry, scanning electron microscopy and EDS technology. Using laser scanning confocal microscope (LSCM), it has been found that the surface of aluminum bronze which wears against titanium alloy is much coarser than the surface which wears against 2Cr13 steel. Results of wear volume show clearly that although the hardness of titanium alloy has greater value than aluminum bronze, the wear volume of titanium alloy has much greater value compared with aluminum bronze. It has been found that there is remarkable material transferring from titanium alloy to aluminum bronze and little material transfer from aluminum bronze to titanium alloy. For the impact-sliding wear between aluminum bronze against 2Cr13 steel, the hardness of aluminum bronze has greater value than 2Cr13 steel, the wear volume of aluminum bronze has much greater value compared with 2Cr13 steel, whose wear volume can be ignored. Using EDS technology, it has been found that there is material transferring from aluminum bronze to 2Cr13 steel and material transferring from 2Cr13 steel to aluminum bronze can be ignored. Through the SEM pictures of worn surfaces and worn debris, flaking, particles and micro-cracks can be found on the worn surfaces. The wear mechanism of aluminum bronze against titanium alloy and 2Cr13 steel is delamination wear.

  16. The effect of magnetospheric erosion on mid- and high-latitude ionospheric flows

    International Nuclear Information System (INIS)

    Freeman, M.P.; Southwood, D.J.

    1988-01-01

    We describe simple quasi-global models of ionospheric flow with the aim of elucidating the potential signatures of magnetopause erosion and allied phenomena at ionospheric heights. Erosion implies the addition of flux to the polar cap and consequently a reduction in the latitude of the polar cap boundary. We consider here the possibility of localized erosion over part of the dayside. Systematic turning of the mid-latitude flow can result to the West and East of the erosion region. After erosion, the boundary must eventually return poleward as stress is released on the nightside. We examine the pattern associated with polar cap boundary reconfiguration. This can give rise to substantial equatorward and tailward flows on closed field lines. We conclude by showing data from the SABRE radar system during a period in which spacecraft measurements have shown erosion is occurring. Various features shown in our models are seen. (author)

  17. An approach to understanding tribological behaviour of dental composites through volumetric wear loss and wear mechanism determination; beyond material ranking.

    Science.gov (United States)

    Altaie, Asmaa; Bubb, Nigel L; Franklin, Paul; Dowling, Adam H; Fleming, Garry J P; Wood, David J

    2017-04-01

    To investigate the fundamental wear mechanisms of six resin-based composite (RBC) formulations during short-term in vitro wear testing. RBC materials were condensed into rectangular bar-shaped specimens and light irradiated using the ISO 4049 specimen manufacture and irradiation protocol. Wear testing (n=10 specimens for each RBC) was performed on a modified pin-on-plate wear test apparatus and wear facets were analysed for wear volume loss using a white light profilometer. The wear tested RBC specimens and their corresponding antagonists were analysed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively to determine the wear mechanism. Data generated using the profilometer showed variations in the mean total wear volume (mm 3 ) between the RBCs tested (ptribology of the system rather than relying on a simple wear ranking for the RBC materials as is routinely the case in dental research studies. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Dental erosion in workers exposed to sulfuric acid in lead storage battery manufacturing facility.

    Science.gov (United States)

    Suyama, Yuji; Takaku, Satoru; Okawa, Yoshikazu; Matsukubo, Takashi

    2010-01-01

    Dental erosion, and specifically its symptoms, has long been studied in Japan as an occupational dental disease. However, in recent years, few studies have investigated the development of this disease or labor hygiene management aimed at its prevention. As a result, interest in dental erosion is comparatively low, even among dental professionals. Our investigation at a lead storage battery factory in 1991 found that the work environmental sulfuric acid density was above the tolerable range (1.0mg/m(3)) and that longterm workers had dental erosion. Therefore, workers handling sulfuric acid were given an oral examination and rates of dental erosion by tooth type, rates of erosion by number of working years and rates of erosion by sulfuric acid density in the work environment investigated. Where dental erosion was diagnosed, degree of erosion was identified according to a diagnostic criterion. No development of dental erosion was detected in the maxillary teeth, and erosion was concentrated in the anterior mandibular teeth. Its prevalence was as high as 20%. Rates of dental erosion rose precipitously after 10 working years. The percentages of workers with dental erosion were 42.9% for 10-14 years, 57.1% for 15-19 years and 66.7% for over 20 years with 22.5% for total number of workers. The percentages of workers with dental erosion rose in proportion to work environmental sulfuric acid density: 17.9% at 0.5-1.0, 25.0% at 1.0-4.0 and 50.0% at 4.0-8.0mg/m(3). This suggests that it is necessary to evaluate not only years of exposure to sulfuric acid but also sulfuric acid density in the air in factory workers.

  19. The effect of wearing jeans on maximum static lifting strength for men and women at various exertion heights.

    Science.gov (United States)

    Chen, Yi-Lang; Li, Chia-Ying; Wang, Chao-Hsuan; Hu, Shiun

    2018-03-13

    This study collected maximum static lifting strength (MSLS) data from 13 males and 13 females at an exertion height of 10-100 cm above the floor (in 10-cm increments) in wearing athletic shorts and wearing jeans conditions. Knee angles were also examined when participants performed the MSLS tasks. Results showed that gender, pant type and exertion height significantly affected participants' MSLS and corresponding knee angle. The effect of wearing jeans primarily occurred at 10-40 cm; meanwhile, male participants tended to stoop while exerting force. This substantially decreased their MSLS (55 N). For female participants in this exertion height range, no significant difference was found in knee angles; accordingly, wearing jeans only slightly affected their MSLS. In summary, wearing jeans had a noticeable effect on the MSLS of male participants, who should be particularly careful when performing lifting tasks at a height of less than 50 cm above the floor.

  20. REDUCED ENGINE FRICTION AND WEAR

    Energy Technology Data Exchange (ETDEWEB)

    Ron Matthews

    2005-05-01

    This Final Technical Report discusses the progress was made on the experimental and numerical tasks over the duration of this project regarding a new technique for decreasing engine friction and wear via liner rotation. The experimental subtasks involved quantifying the reduction in engine friction for a prototype rotating liner engine relative to a comparable baseline engine. Both engine were single cylinder conversions of nominally identical production four-cylinder engines. Hot motoring tests were conducted initially and revealed that liner rotation decreased engine friction by 20% under motoring conditions. A well-established model was used to estimate that liner rotation should decrease the friction of a four-cylinder engine by 40% under hot motoring conditions. Hot motoring tear-down tests revealed that the crankshaft and valve train frictional losses were essentially the same for the two engines, as expected. However, the rotating liner engine had much lower (>70%) piston assembly friction compared to the conventional engine. Finally, we used the Instantaneous IMEP method to compare the crank-angle resolved piston assembly friction for the two engines. Under hot motoring conditions, these measurements revealed a significant reduction in piston assembly friction, especially in the vicinity of compression TDC when the lubrication regime transitions from hydrodynamic through mixed and into boundary friction. We have some remaining problems with these measurements that we expect to solve during the next few weeks. We will then perform these measurements under firing conditions. We also proposed to improve the state-of-the-art of numerical modeling of piston assembly friction for conventional engines and then to extend this model to rotating liner engines. Our research team first modeled a single ring in the Purdue ring-liner test rig. Our model showed good agreement with the test rig data for a range of speeds and loads. We then modeled a complete piston

  1. Quantitive dynamical wear analysis and the convergent quest for significant wear reduction

    International Nuclear Information System (INIS)

    Sellschop, F.; Kirsch, J.; Derry, T.; Marcus, R.

    1984-01-01

    The maturing of nuclear physics has made the development of ion beam modification of materials possible, bringing new skills and prospects to the world of materials science. In the following paper an outline is given of the history of ion beam modification of materials (IBMM) and its use for altering the surface of metals to combat wear and friction, and monitoring wear in engines

  2. In vitro wear of resin-based materials--simultaneous corrosive and abrasive wear.

    Science.gov (United States)

    Correr, Gisele Maria; Bruschi Alonso, Roberta Caroline; Correr Sobrinho, Lourenço; Puppin-Rontani, Regina Maria; Ferracane, Jack Liborio

    2006-07-01

    The aim of this study was to evaluate the wear of resin-based materials caused by the association of abrasive and corrosive processes. Twenty specimens were prepared for each material, cast in epoxy in acrylic rings, polished, and profiled with an MTS 3D Profiler. Antagonists were made from deciduous molars. Specimens were distributed into eight groups (n = 10), according to the material (Filtek Supreme, Point 4, Dyract AP, and Fuji II LC) and the type of slurry (neutral and acidic), and then cycled 100,000 times in the OHSU oral wear simulator. The specimens were cleaned and reprofiled. Volume loss and maximum depth were determined. ANOVA and Tukey's test were used for data analysis (p wear facet on the antagonist was also measured. Composites displayed less wear than the compomer and the resin-modified glass ionomer. Significant differences also were found for cusp wear, with a significant positive correlation shown between cusp and material wear. The acidic slurry significantly increased the wear of the materials compared to the neutral slurry. Exposure to acidic slurry accelerated the wear of resin-based materials.

  3. Wear mechanisms and friction parameters for sliding wear of micron-scale polysilicon sidewalls

    NARCIS (Netherlands)

    Alsem, D. H.; van der Hulst, R.; Stach, E. A.; Dugger, M. T.; De Hosson, J. Th. M.; Ritchie, R. O.

    As tribological properties are critical factors in the reliability of silicon-based microelectromechanical systems, it is important to understand what governs wear and friction. Average dynamic friction, wear volumes and morphology have been studied for polysilicon devices fabricated using the

  4. Determination of riverbank erosion probability using Locally Weighted Logistic Regression

    Science.gov (United States)

    Ioannidou, Elena; Flori, Aikaterini; Varouchakis, Emmanouil A.; Giannakis, Georgios; Vozinaki, Anthi Eirini K.; Karatzas, George P.; Nikolaidis, Nikolaos

    2015-04-01

    erosion occurrence probability can be calculated in conjunction with the model deviance regarding the independent variables tested. The most straightforward measure for goodness of fit is the G statistic. It is a simple and effective way to study and evaluate the Logistic Regression model efficiency and the reliability of each independent variable. The developed statistical model is applied to the Koiliaris River Basin on the island of Crete, Greece. Two datasets of river bank slope, river cross-section width and indications of erosion were available for the analysis (12 and 8 locations). Two different types of spatial dependence functions, exponential and tricubic, were examined to determine the local spatial dependence of the independent variables at the measurement locations. The results show a significant improvement when the tricubic function is applied as the erosion probability is accurately predicted at all eight validation locations. Results for the model deviance show that cross-section width is more important than bank slope in the estimation of erosion probability along the Koiliaris riverbanks. The proposed statistical model is a useful tool that quantifies the erosion probability along the riverbanks and can be used to assist managing erosion and flooding events. Acknowledgements This work is part of an on-going THALES project (CYBERSENSORS - High Frequency Monitoring System for Integrated Water Resources Management of Rivers). The project has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: THALES. Investing in knowledge society through the European Social Fund.

  5. Sand erosion at the toe of a gabion-protected dune face

    NARCIS (Netherlands)

    Chapman, A.

    1992-01-01

    The purpose of this research project was to study the manner in which erosion takes place the the toe of a dune slope protected by gabions, and to examine the response of the gabions to this erosion. A sand slope overlaid by model gabions was subjected to wave attack in a hydraulic flume, and

  6. Corneo-scleral limbal changes following short-term soft contact lens wear.

    Science.gov (United States)

    Consejo, Alejandra; Bartuzel, Maciej M; Iskander, D Robert

    2017-10-01

    To assess whether short-term soft contact lens wear alters the anterior eye surface. Twenty-two neophyte subjects wore soft contact lenses for a period of five hours. Topography based corneo-scleral limbal radius estimates were derived from height measurements acquired with a corneo-scleral profilometer. Additionally, central corneal thickness (CCT), anterior chamber depth (ACD), corneal curvature radius (R) and white-to-white (WTW) diameter were acquired with an OCT-assisted biometer. Measurements were obtained without lens wear (baseline), immediately after lens removal following five hours of wear and three hours after lens removal. Short-term soft contact lens wear significantly modifies corneo-scleral limbal radius (mean±SD: 130±74μm, p contact lens wear. The increment in the limbal diameter could reach over 0.5mm but that alteration does not correspond to changes in WTW diameter and it was not observable to the examiner using a slit lamp. Assessing topographical limbus after contact lens wear could be a tool to optimize the selection of the contact lens, from the perspective of anterior eye surface changes. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  7. Dry Sliding Wear Behavior of EN25 Steel Treated by Different Quenching Media

    Directory of Open Access Journals (Sweden)

    Bassam Ali Ahmed

    2010-10-01

    Full Text Available The present investigation aims to study the effect of heat treatment by quenching in different quenching media (salt water, water and oil following by tempering on wear resistance of EN25 steel. EN25 steel is an alloy of medium carbon low alloy steel which is used for many applications requiring high tensile strength and wear resistance such as connecting rods, adapters and in power sectors extensively. The specimens are machined to 20 mm in length and 10 mm in diameter. This study is done by two stages: The first stage is done by austenitizing EN25 steel to 850 for 1 hr by quenching the specimens in three different quenching media and then tempered at 300 in air. While the second stage is performed by wear test. Dry sliding wear test is done by using pin –on-disc technique by varying the loads as 5, 10, 15, 20 and 25 N, also varying the time as 5, 10, 15, 20, 25 and 30 min respectively. The microstructure examination, hardness and followed roughness tests are also done for the specimens before and after wear test. The results of this work showed that an improving in wear resistance and hardness for the specimen quenched by salt water more than for water and oil. At the same time the roughness decreasing for the specimen quenched by salt water more than for water and oil.

  8. Association of CD8+ T-cells with bone erosion in patients with rheumatoid arthritis.

    Science.gov (United States)

    Joo, Young Bin; Park, Youngho; Kim, Kwangwoo; Bang, So-Young; Bae, Sang-Cheol; Lee, Hye-Soon

    2018-02-01

    Bone erosion is a major problem worsening quality of rheumatoid arthritis (RA) patients' lives. However, causal factors responsible for bone erosion in RA have remained unclear. We aimed to examine genetic variants conferring bone erosion in RA using a Korean genome-wide association study (GWAS) and to search for possible biological mechanisms underlying the development of bone erosion. We obtained genome-wide single nucleotide polymorphism (SNP) data for 711 Korean RA patients using Illumina HapMap 550v3/660W arrays. Associations between SNPs and bone erosion status based on the Steinbrocker staging system were examined using multivariate logistic regression. Cell-type-specific enrichment of the epigenomic chromatin annotation H3K4me3 at the bone erosion associated variants was further investigated using National Institute of Health Roadmap Epigenomics data. As we tested the associations between 439 289 SNPs and bone erosion in 385 patients with erosive RA and 326 with non-erosive RA, none of the tested SNPs reached the genome-wide significance threshold, although many loci showed modest genetic effect on bone erosion status with suggestive association (e.g., rs2741200 [P = 3.75 × 10 -6 ] in the SLA-TG locus and rs12422918 [P = 4.13 × 10 -6 ] in SRGAP1). However, the top-ranked SNPs and their linked proxies, which were mostly located in non-coding variants, were significantly co-localized with the highly tissue-specific regulatory marker H3K4me3 in CD8 + memory T-cells (P = 0.014). Although, there was no large-effect variants associated with bone erosion in our GWAS, we have shown that CD8 + memory T-cells may have relevance with bone erosion in patients with RA through the analysis of ChiP-seq data. © 2017 Asia Pacific League of Associations for Rheumatology and John Wiley & Sons Australia, Ltd.

  9. Wear and corrosion behaviour of tungsten carbide based coatings with different metallic binder

    Science.gov (United States)

    Kamdi, Z.; Apandi, M. N. M.; Ibrahim, M. D.

    2017-12-01

    Tungsten carbide based coating has been well known as wear and corrosion resistance materials. However, less study is done on comparing the coating with different binder. Thus, in this work the wear and corrosion behaviour of high velocity oxy-fuel (HVOF) coatings, namely (i) tungsten carbide cobalt and (ii) tungsten carbide nickel will be evaluated. Both coatings were characterised using X-ray Diffractometer (XRD) and Scanning Electron Microscope (SEM). The wear behaviour has been examined using the modified grinder machine by weight loss measurement. Two types of abrasive have been used that include 3 g by weight alumina and silica. While for the corrosion behaviour, it is monitored by three electrodes of electrochemical test and immersion test for 30 days in an acidic environment. The electrolyte used was 0.5 M sulphuric acids (H2SO4). It was found that the cobalt binder shows higher wear resistance compares to the nickel binder for both slurry types. The harder alumina compared to silica results in higher wear rate with removal of carbide and binder is about the same rate. For silica abrasive, due to slightly lower hardness compared to the carbide, the wear is dominated by binder removal followed by carbide detachment. For corrosion, the nickel binder shows four times higher wear resistance compared to the cobalt binder as expected due to its natural behaviour. These finding demonstrate that the selection of coating to be used in different application in this case, wear and corrosion shall be chosen carefully to maximize the usage of the coating.

  10. Type and timing of dietary acid intake and tooth wear among American adults.

    Science.gov (United States)

    Al-Zwaylif, Lynn H; O'Toole, Saoirse; Bernabé, Eduardo

    2018-01-11

    To explore the interrelationship between type and timing of dietary acid intake and tooth wear among American adults. This study used data from 3,586 adults, aged 18 years and older, who participated in the National Health and Nutrition Examination Survey (NHANES) 2003-04. Information on four types of acidic food and beverages (fruits, fruit juices, alcoholic drinks, and soft drinks) and timing of consumption (meals versus snacks, defined according to percentage of total energy intake, self-reported eating occasion, and time of day) was extracted from two 24-hour dietary recalls. The association of the type and timing of dietary acid intake with the number of surfaces with moderate-to-severe tooth wear was assessed in Hurdle models to account for the excess zero counts and over-dispersion. Models were adjusted for socio-demographic factors, acid reflux medication, and dental insurance coverage. The daily intake of soft drinks was associated with tooth wear, while those of fruits, fruit juices, and alcoholic drinks were not. The consumption of soft drinks with meals was the only factor consistently associated with tooth wear, irrespective of the method used to define meals versus snacks. The above associations were found with the number of surfaces with tooth wear (among those with the condition), but not with the odds of having tooth wear (among all participants). The consumption of soft drinks with meals was associated with moderate-to-severe tooth wear among American adults. Other acidic foods and beverages were not associated with tooth wear, regardless of their timing of consumption. © 2018 American Association of Public Health Dentistry.

  11. Using stamping punch force variation for the identification of changes in lubrication and wear mechanism

    Science.gov (United States)

    Voss, B. M.; Pereira, M. P.; Rolfe, B. F.; Doolan, M. C.

    2017-09-01

    The growth in use of Advanced High Strength Steels in the automotive industry for light-weighting and safety has increased the rates of tool wear in sheet metal stamping. This is an issue that adds significant costs to production in terms of manual inspection and part refinishing. To reduce these costs, a tool condition monitoring system is required and a firm understanding of process signal variation must form the foundation for any such monitoring system. Punch force is a stamping process signal that is widely collected by industrial presses and has been linked closely to part quality and tool condition, making it an ideal candidate as a tool condition monitoring signal. In this preliminary investigation, the variation of punch force due to different lubrication conditions and progressive wear are examined. Linking specific punch force signature changes to developing lubrication and wear events is valuable for die wear and stamping condition monitoring. A series of semi-industrial channel forming trials were conducted under different lubrication regimes and progressive die wear. Punch force signatures were captured for each part and Principal Component Analysis (PCA) was applied to determine the key Principal Components of the signature data sets. These Principal Components were linked to the evolution of friction conditions over the course of the stroke for the different lubrication regimes and mechanism of galling wear. As a result, variation in punch force signatures were correlated to the current mechanism of wear dominant on the formed part; either abrasion or adhesion, and to changes in lubrication mechanism. The outcomes of this study provide important insights into punch force signature variation, that will provide a foundation for future work into the development of die wear and lubrication monitoring systems for sheet metal stamping.

  12. Dental Erosion and Dentin Hypersensitivity among Adult Asthmatics and Non-asthmatics Hospital-based: A Preliminary Study.

    Science.gov (United States)

    Farag, Zahra Hassan Abdelaziz; Awooda, Elhadi Mohieldin

    2016-01-01

    Asthma is a chronic inflammatory condition affecting the airways leading to spasm and swelling of the airways. The medications taken for the treatment of asthma can result in dental erosion and dentin hypersensitivity. The aims of this study were to investigate the severity of dental erosion amongst adult asthmatics according to: gender, type and duration of medication taken and to compare dental erosion and dentin hypersensitivity between asthmatics and non-asthmatics. Comparative, cross-sectional hospital based study among 40 asthmatics (M=15 & F=25) and 40 non-asthmatics (M=18 & F=22) in the age range of 18-60 year selected purposefully from Al-Shaab Teaching Hospital in Khartoum city. The Basic Erosive Wear Index was used for dental erosion assessment. Dentine hypersensitivity was determined by giving ice cold water and rated using the Visual Analogue Scale. Chi-square and Student's t-test were used for statistical analysis with P value ≤.05. There was an association between severity of dental erosion and presence of asthma (P=0.03), where asthmatics had a higher degree of erosion (moderate and severe) and non-asthmatics a lower degree. No significant association was found between dental erosion and gender, type and duration of medication among asthmatics group. A statistically significant difference was revealed in the degree of dentin hypersensitivity (P=0.00) among asthmatics (35.13%) and non-asthmatics (14.13%). Asthmatic patients had a higher degree of dental erosion and dentin hypersensitivity compared to non-asthmatics. Among asthmatic patients there was no association between severity of dental erosion and gender, type and duration medication was taken for.

  13. Assessment of fretting wear in Hanaro fuel

    International Nuclear Information System (INIS)

    Chae, Hee Taek; Lim, Kyeong Hwan; Kim, Hark Rho

    1999-06-01

    Since the first fuel loading on Feb. 1995, various zero-power tests were performed in HANARO and power ascending tests followed. After the initial fuel loading, Hanaro operation staffs inspected only two fuel bundles which were evaluated to have the highest power at the end of each cycle and they did not recognize anything peculiar in the inspected bundles. At the end of 1996, Hanaro staffs found severe wear damages in the fuel components. After that, the 4th cycle core was re-arranged with fresh fuels only to investigate wear phenomena on the fuel components. The fuel inspections have been performed 25 times periodically since the core re-configuration. In this report, fretting wear characteristics of the fuel assemblies were evaluated and summarized. Wear damages of the improved fuel assembly to resolve the wear problem were compared with those of the original fuel assembly. Based on the results of the fuel inspections, we suggest that fuel inspection need not be done for the first 60 pump operation days in order to reduce the potential of damage by a fuel handling error and an operator's burden of the fuel inspection. (author). 6 refs., 10 tabs., 5 figs

  14. Investigation on wear characteristic of biopolymer gear

    Science.gov (United States)

    Ghazali, Wafiuddin Bin Md; Daing Idris, Daing Mohamad Nafiz Bin; Sofian, Azizul Helmi Bin; Basrawi, Mohamad Firdaus bin; Khalil Ibrahim, Thamir

    2017-10-01

    Polymer is widely used in many mechanical components such as gear. With the world going to a more green and sustainable environment, polymers which are bio based are being recognized as a replacement for conventional polymers based on fossil fuel. The use of biopolymer in mechanical components especially gear have not been fully explored yet. This research focuses on biopolymer for spur gear and whether the conventional method to investigate wear characteristic is applicable. The spur gears are produced by injection moulding and tested on several speeds using a custom test equipment. The wear formation such as tooth fracture, tooth deformation, debris and weight loss was observed on the biopolymer spur gear. It was noted that the biopolymer gear wear mechanism was similar with other type of polymer spur gears. It also undergoes stages of wear which are; running in, linear and rapid. It can be said that the wear mechanism of biopolymer spur gear is comparable to fossil fuel based polymer spur gear, thus it can be considered to replace polymer gears in suitable applications.

  15. Brake wear particle emissions: a review.

    Science.gov (United States)

    Grigoratos, Theodoros; Martini, Giorgio

    2015-02-01

    Traffic-related sources have been recognized as a significant contributor of particulate matter particularly within major cities. Exhaust and non-exhaust traffic-related sources are estimated to contribute almost equally to traffic-related PM10 emissions. Non-exhaust particles can be generated either from non-exhaust sources such as brake, tyre, clutch and road surface wear or already exist in the form of deposited material at the roadside and become resuspended due to traffic-induced turbulence. Among non-exhaust sources, brake wear can be a significant particulate matter (PM) contributor, particularly within areas with high traffic density and braking frequency. Studies mention that in urban environments, brake wear can contribute up to 55 % by mass to total non-exhaust traffic-related PM10 emissions and up to 21 % by mass to total traffic-related PM10 emissions, while in freeways, this contribution is lower due to lower braking frequency. As exhaust emissions control become stricter, relative contributions of non-exhaust sources-and therefore brake wear-to traffic-related emissions will become more significant and will raise discussions on possible regulatory needs. The aim of the present literature review study is to present the state-of-the-art of the different aspects regarding PM resulting from brake wear and provide all the necessary information in terms of importance, physicochemical characteristics, emission factors and possible health effects.

  16. Brush seal shaft wear resistant coatings

    Science.gov (United States)

    Howe, Harold

    1995-03-01

    Brush seals suffer from high wear, which reduces their effectiveness. This work sought to reduce brush seal wear by identifying and testing several industry standard coatings. One of the coatings was developed for this work. It was a co-sprayed PSZ with boron-nitride added for a high temperature dry lubricant. Other coatings tested were a PSZ, chrome carbide and a bare rotor. Testing of these coatings included thermal shocking, tensile testing and wear/coefficient of friction testing. Wear testing consisted of applying a coating to a rotor and then running a sample tuft of SiC ceramic fiber against the coating. Surface speeds at point of contact were slightly over 1000 ft/sec. Rotor wear was noted, as well as coefficient of friction data. Results from the testing indicates that the oxide ceramic coatings cannot withstand the given set of conditions. Carbide coatings will not work because of the need for a metallic binder, which oxidizes in the high heat produced by friction. All work indicated a need for a coating that has a lubricant contained within itself and the coating must be resistant to an oxidizing environment.

  17. Wear mechanisms of Al2O3/TiC/Mo/Ni ceramic wire-drawing dies

    International Nuclear Information System (INIS)

    Deng Jianxin; Yang Xuefeng; Wang Jinghai

    2006-01-01

    Al 2 O 3 /TiC/Mo/Ni ceramic composites were produced by hot-pressing for the use of wire drawing dies. The fundamental properties of these ceramic die materials were examined. Wire drawing tests were carried out on the 65Mn steel wire with these ceramic dies. Finite element method (FEM) was used as a means of numerically evaluating stress and its distribution inside the ceramic drawing dies. Worn bore surfaces of the ceramic drawing dies were examined by scanning electron microscopy (SEM). The wear mechanisms of the ceramic drawing dies were investigated. Detailed observations and analyses of the die wear surface have revealed that the most common failure of the ceramic drawing die is the wear at its approach zone. FEM analysis showed that the compressive stresses on both sides of the corners at the approach zone are higher than those of other parts of the ceramic drawing die. Abrasive and adhesive wear were found to be the predominant wear mechanisms through the whole approach zone owing to the greater compressive stresses. Examination of the center bore surface at the die bearing zone of the ceramic drawing dies demonstrated that the wear occurred by light abrasive, no adhesion wear was observed

  18. Erosion and lateral surface processes

    Science.gov (United States)

    : Erosion can cause serious agricultural and environmental hazards. It can generate severe damage to the landscape, lead to significant loss of agricultural land and consequently to reduction in agricultural productivity, induce surface water pollution due to the transport of sediments and suspende...

  19. Extraarticular abrasive wear in cemented and cementless total knee arthroplasty.

    Science.gov (United States)

    Noble, Philip C; Conditt, Michael A; Thompson, Matthew T; Stein, Jason A; Kreuzer, Stephan; Parsley, Brian S; Mathis, Kenneth B

    2003-11-01

    In this study, we examine the contributions of periprosthetic impingement to a seldom recognized source of PE damage resulting in gouging, abrasion, and severe localized damage in cemented and cementless total knee replacement. One hundred sixty two tibial components of 34 different designs in a retrieval collection were examined. The presence and location of abrasive wear to the nonarticulating edges of the insert were measured, with representative specimens examined using SEM. Significant abrasive wear was observed in 35% of the retrievals with cemented femoral components and 25% from noncemented components. Within the group of worn inserts, abrasive scars were seen with a frequency of 75% on the extreme medial edge, 20% on the extreme lateral edge, 26% on the posteromedial edge, and 16% on the posterolateral edge. The role of extraarticular impingement in this damage mode was confirmed by examination of retrieved femoral components with overhanging cement or embedded osteophytes. In the majority of cases, this complication may be avoided by careful removal of excess cement and extracortical osteophytes.

  20. An abrasive wear study of ordered Fe[sub 3]Al. [Fe[sub 73]Al[sub 27], Fe[sub 76]Al[sub 24], Fe[sub 77]Al[sub 23

    Energy Technology Data Exchange (ETDEWEB)

    Maupin, H.E.; Wilson, R.D.; Hawk, J.A. (US Bureau of Mines, Albany Research Center, OR (United States))

    1992-12-01

    Abrasive wear research has been conducted on ordered iron aluminide intermetallics. Pin-on-drum abrasive wear tests were performed on samples of varying long-range order. Wear surfaces were examined with optical microscopy, transmission electron microscopy (TEM), scanning electron microscopy and X-ray diffraction. The wear mechanism consisted of microplowing, micromachining and microfracture. Compositional variation near Fe[sub 3]Al and the degree of long-range ordering had only minor effects on the abrasive wear rates of iron aluminide samples. TEM analysis of the wear surfaces indicated that significant plastic deformation and recrystallization had occurred. The abrasive wear rates were compared with those of well-known abrasive wear-resistant materials. (orig.).

  1. Friction and wear performance of ion-beam deposited diamondlike carbon films on steel substrates

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, A.; Nichols, F.A.; Pan, X.Z. [Argonne National Lab., IL (United States). Materials and Components Technology Div.; Wei, R.; Wilbur, P. [Colorado State Univ., Fort Collins, CO (United States). Dept. of Mechanical Engineering

    1993-01-01

    In this study, we investigated the friction and wear performance of ion-beam-deposited diamondlike-carbon (DLC) films (1.5 {mu}m thick) on AISI 440C steel substrates. Furthermore, we ran a series of long-duration wear tests under 5, 10, and 20 N load to assess the load-bearing capacity and durability limits of these films under each load. Tests were performed on a ball-on-disk machine in open air at room temperature {approx} 22{plus_minus}1{degrees}C, and humidity, {approx} 30{plus_minus}5%. For the test conditions explored, we found that (1) the steady-state friction coefficients of pairs without a DLC film were in the range of 0.7 to 0.9 and the average wear rates of 440C balls (9.55 mm diameter) sliding against uncoated 440C disks were on the order of 10{sup {minus}5} mm{sup 3}/N.m, depending on contact load; (2) DLC films reduced the steady-state friction coefficients of test pairs by factors of 6 to 8, and the wear rates of pins by factors of 500 to 2000; (3) The wear of disks coated with a DLC film was virtually unmeasurable while the wear of uncoated disks was quite substantial, (4) these DLC films were able to endure the range of loads, 5 to 20 N, without any delamination and to last over a million cycles before wearing out. During long-duration wear tests, the friction coefficients were initially on the order of 0.15, but decreased to some low values of 0.05 to 0.07 after sliding for 15 to 25 km, depending on the load, and remained low until wearing out. This low-friction regime was correlated with the formation of a carbon-rich transfer film on the wear scar of 440C balls. Micro-laser-Raman spectroscopy and scanning-electron microscopy were used to examine the structure and chemistry of worn surfaces and to elucidate the wear- and friction-reducing mechanisms of the DLC film.

  2. Friction and wear performance of ion-beam deposited diamondlike carbon films on steel substrates

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, A.; Nichols, F.A.; Pan, X.Z. (Argonne National Lab., IL (United States). Materials and Components Technology Div.); Wei, R.; Wilbur, P. (Colorado State Univ., Fort Collins, CO (United States). Dept. of Mechanical Engineering)

    1993-01-01

    In this study, we investigated the friction and wear performance of ion-beam-deposited diamondlike-carbon (DLC) films (1.5 [mu]m thick) on AISI 440C steel substrates. Furthermore, we ran a series of long-duration wear tests under 5, 10, and 20 N load to assess the load-bearing capacity and durability limits of these films under each load. Tests were performed on a ball-on-disk machine in open air at room temperature [approx] 22[plus minus]1[degrees]C, and humidity, [approx] 30[plus minus]5%. For the test conditions explored, we found that (1) the steady-state friction coefficients of pairs without a DLC film were in the range of 0.7 to 0.9 and the average wear rates of 440C balls (9.55 mm diameter) sliding against uncoated 440C disks were on the order of 10[sup [minus]5] mm[sup 3]/N.m, depending on contact load; (2) DLC films reduced the steady-state friction coefficients of test pairs by factors of 6 to 8, and the wear rates of pins by factors of 500 to 2000; (3) The wear of disks coated with a DLC film was virtually unmeasurable while the wear of uncoated disks was quite substantial, (4) these DLC films were able to endure the range of loads, 5 to 20 N, without any delamination and to last over a million cycles before wearing out. During long-duration wear tests, the friction coefficients were initially on the order of 0.15, but decreased to some low values of 0.05 to 0.07 after sliding for 15 to 25 km, depending on the load, and remained low until wearing out. This low-friction regime was correlated with the formation of a carbon-rich transfer film on the wear scar of 440C balls. Micro-laser-Raman spectroscopy and scanning-electron microscopy were used to examine the structure and chemistry of worn surfaces and to elucidate the wear- and friction-reducing mechanisms of the DLC film.

  3. A methodology for testing the erosive potential of sports drinks.

    Science.gov (United States)

    Hooper, S M; Hughes, J A; Newcombe, R G; Addy, M; West, N X

    2005-04-01

    The aim of the study was to develop and test a methodology in situ, which simulated the consumption of sports drinks. A secondary aim was to assess the acceptability of the method to sedentary participants. To select the sports drink for the study in situ, five commercially available sports drinks were examined for erosive potential in vitro. The study in situ was a single centre, 2-period, 2-treatment crossover study to compare the erosive effect of a commercially available sports drink (Test), with that of mineral water (Control), over 10 day periods on 10 healthy volunteers. Subjects wore upper removable appliances containing two human enamel specimens from 9 a.m. to 5 p.m. The regimen of intake of the drinks was 350 ml in 10, 5-min rest, 650 ml in 25, 5-min rest, 500 ml in 10 and 5-min rest. Measurements of enamel loss were made on samples after 5 and 10 days by profilometry. The in situ study showed a statistically significant difference in erosive potential between the test and control beverages. No specimen exposed to the control beverage displayed appreciable erosion. Erosion occurred with the test drink, but to a variable degree between subjects. The subjects unanimously found the drinking regimen unpleasant. The sports drink caused significantly more erosion in situ than water and as seen in other studies, there was marked variation in susceptibility to erosion between subjects. The new drinking regimen was designed to simulate pre, during and post-exercise intake. Although all the sedentary subjects participating in this study reported that they found the volume of fluids consumed over a short period of time excessive it is unlikely that this would prove problematic in the exercise environment.

  4. Delamination wear mechanism in gray cast irons

    International Nuclear Information System (INIS)

    Salehi, M.

    2000-01-01

    An investigation of the friction and sliding wear of gray cast iron against chromium plated cast irons was carried out on a newly constructed reciprocating friction and wear tester. The tests were the first to be done on the test rig under dry conditions and at the speed of 170 cm/min, and variable loads of 20-260 N for a duration of 15 min. to 3 hours. The gray cast iron surfaces worn by a process of plastic deformation at the subsurface, crack nucleation, and crack growth leading to formation of plate like debris and therefore the delamination theory applies. No evidence of adhesion was observed. This could be due to formation of oxides on the wear surface which prevent adhesion. channel type chromium plating ''picked'' up cast iron from the counter-body surfaces by mechanically trapping cast iron debris on and within the cracks. The removal of the plated chromium left a pitted surface on the cast iron

  5. The mechanics of wear in slurry dumping

    International Nuclear Information System (INIS)

    Miller, J.E.

    1986-01-01

    This paper deals with the pumping of abrasive slurries which exposes machinery and parts to an exceedingly large number of modes of wear, probably representing all possible modes that can be conceived. The term ''slurry'' as defined implies that the abrasive solids are mixed with a liquid, usually water, which can combine with certain soluble elements from the solids or from the atmosphere to form an insidious combination of corrosion-abrasion. The various wear modes are described and exemplified with drawings and photographs. A discussion on wear reduction and operating practices is included. A brief description of the ASTM G75 Miller Number Test for slurry abrasivity and a proposed Slurry Abrasion Resistance Test for the effect of slurries on materials is included

  6. Wear Resistant Amorphous and Nanocomposite Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Racek, O

    2008-03-26

    Glass forming materials (critical cooling rate <10{sup 4}K.s{sup -1}) are promising for their high corrosion and wear resistance. During rapid cooling, the materials form an amorphous structure that transforms to nanocrystalline during a process of devitrification. High hardness (HV 1690) can be achieved through a controlled crystallization. Thermal spray process has been used to apply coatings, which preserves the amorphous/nanocomposite structure due to a high cooling rate of the feedstock particles during the impact on a substrate. Wear properties have been studied with respect to process conditions and feedstock material properties. Application specific properties such as sliding wear resistance have been correlated with laboratory tests based on instrumented indentation and scratch tests.

  7. Overview of PVD wear resistant coatings

    International Nuclear Information System (INIS)

    Teeter, F.J.

    1999-01-01

    The combined functionality of wear-resistant and low-friction multilayer coatings has widened application possibilities for a new generation of coated tools. For the first time tool wear mechanisms are comprehensively addressed both at the cutting edge and contact areas away from the edge where chip evacuation is facilitated. Since its recent market introduction a combined TiA1N and WC/C PVD coating has been proven to increase cutting performance in various metal cutting operations, notably drilling and tapping of steels and aluminum alloys. Significant improvements have been obtained under dry as well as with coolant conditions. The results of laboratory metal cutting tests and field trials to date will be described. Correlations between chip formation / wear mechanisms and coating properties are given to explain the effectiveness of this coating. (author)

  8. Quantitative wear particle analysis for osteoarthritis assessment.

    Science.gov (United States)

    Guo, Meizhai; Lord, Megan S; Peng, Zhongxiao

    2017-12-01

    Osteoarthritis is a degenerative joint disease that affects millions of people worldwide. The aims of this study were (1) to quantitatively characterise the boundary and surface features of wear particles present in the synovial fluid of patients, (2) to select key numerical parameters that describe distinctive particle features and enable osteoarthritis assessment and (3) to develop a model to assess osteoarthritis conditions using comprehensive wear debris information. Discriminant analysis was used to statistically group particles based on differences in their numerical parameters. The analysis methods agreed with the clinical osteoarthritis grades in 63%, 50% and 61% of particles for no osteoarthritis, mild osteoarthritis and severe osteoarthritis, respectively. This study has revealed particle features specific to different osteoarthritis grades and provided further understanding of the cartilage degradation process through wear particle analysis - the technique that has the potential to be developed as an objective and minimally invasive method for osteoarthritis diagnosis.

  9. Laser cladding of wear resistant metal matrix composite coatings

    International Nuclear Information System (INIS)

    Yakovlev, A.; Bertrand, Ph.; Smurov, I.

    2004-01-01

    A number of coatings with wear-resistant properties as well as with a low friction coefficient are produced by laser cladding. The structure of these coatings is determined by required performance and realized as metal matrix composite (MMC), where solid lubricant serves as a ductile matrix (e.g. CuSn), reinforced by appropriate ceramic phase (e.g. WC/Co). One of the engineered coating with functionally graded material (FGM) structure has a dry friction coefficient 0.12. Coatings were produced by coaxial injection of powder blend into the zone of laser beam action. Metallographic and tribological examinations were carried out confirming the advanced performance of engineered coatings

  10. Surface erosion issues and analysis for dissipative divertors

    International Nuclear Information System (INIS)

    Brooks, J.N.; Ruzic, D.N.; Hayden, D.B.; Turkot, R.B. Jr.

    1994-05-01

    Erosion/redeposition is examined for the sidewall of a dissipative divertor using coupled impurity transport, charge exchange, and sputtering codes, applied to a plasma solution for the ITER design. A key issue for this regime is possible runaway self-sputtering, due to the effect of a low boundary density and nearly parallel field geometry on redeposition parameters. Net erosion rates, assuming finite self-sputtering, vary with wall location, boundary conditions, and plasma solution, and are roughly of the following order: 200--2000 angstrom/s for beryllium, 10--100 angstrom/s for vanadium, and 0.3--3 angstrom/s for tungsten

  11. Modeling erosion from forest roads with WEPP

    Science.gov (United States)

    J. McFero Grace

    2007-01-01

    Forest roads can be major sources of soil erosion from forest watersheds. Sediments from forest roads are a concern due to their potential delivery to stream systems resulting in degradation of water quality. The Water Erosion Prediction Project (WEPP) was used to predict erosion from forest road components under different management practices. WEPP estimates are...

  12. Soil Erosion. LC Science Tracer Bullet.

    Science.gov (United States)

    Buydos, John F., Comp.

    Soil erosion is the detachment and movement of topsoil or soil material from the upper part of the soil profile. It may occur in the form of rill, gully, sheet, or wind erosion. Agents of erosion may be water, wind, glacial ice, agricultural implements, machinery, and animals. Soil conservation measures require a thorough understanding of the…

  13. Natural and anthropogenic rates of soil erosion

    Science.gov (United States)

    Regions of land that are brought into crop production from native vegetation typically undergo a period of soil erosion instability, and long term erosion rates are greater than for natural lands as long as the land continues being used for crop production. Average rates of soil erosion under natur...

  14. Soil erosion in humid regions: a review

    Science.gov (United States)

    Daniel J. Holz; Karl W.J. Williard; Pamela J. Edwards; Jon E. Schoonover

    2015-01-01

    Soil erosion has significant implications for land productivity and surface water quality, as sediment is the leading water pollutant worldwide. Here, erosion processes are defined. The dominant factors influencing soil erosion in humid areas are reviewed, with an emphasis on the roles of precipitation, soil moisture, soil porosity, slope steepness and length,...

  15. Measurements of Sediment Erosion and Transport with the ASSET Flume

    Science.gov (United States)

    Jepsen, R. A.; Roberts, J. D.; James, S. C.

    2003-12-01

    Soil and sediments play an important role in water management and water quality. Issues such as water turbidity, associated contaminants, reservoir sedimentation, undesirable erosion and scour, and aquatic habitat are all linked to sediment properties and behaviors. In situ analysis is necessary to develop an understanding of the erosion and transport of sediments. Sandia National Laboratories has recently patented the ASSET Flume that quantifies in situ erosion of a sediment core with depth while affording simultaneous examination of transport modes (bedload vs. suspended load) of the eroded material. Core erosion rates and ratios of bedload to suspended load transport of quartz sediments were studied with the ASSET Flume. The erosion and transport of a fine-grained natural cohesive sediment were also observed. Experiments using quartz sands revealed that the ratio of suspended load to bedload sediment transport is a function of grain diameter and shear stress at the sediment surface. Data collected from the ASSET Flume were used to formulate a novel empirical relation for predicting the ratio of bedload to suspended load as a function of shear stress and grain diameter for non-cohesive sediments.

  16. The Impact of Farming and Land Ownership on Soil Erosion

    Directory of Open Access Journals (Sweden)

    Olga Čermáková

    2014-01-01

    Full Text Available The aim of this paper was to compare two methods of farming, especially their effect on water soil erosion. The examined methods were (1 large-scale farming, where more than 50% of the land was leased, and (2 small-scale farming, where the land was almost exclusively privately owned. The research area was 8 cadastres in the district of Hodonín, South Moravia, Czech Republic. In these cadastres 48 land blocks representing both large-scale and small-scale farming (i.e. owners and tenants were chosen. The long-term average annual soil loss caused by water erosion (G was calculated using the erosion model USLE 2D and ArcGIS 10.1. The nonparametric Mann-Whitney test was used for the statistical evaluation of the data. The difference between the soil loss (G on land blocks farmed by small producers (owners and large producers (tenants was significant (p < 0.05. Differences between the values of the cropping-management factor (C were not statistically significant (p = 0.054. Based on the analysis of other variables in the USLE equation it can be stated that a continuous slope length, conditioned by the size of land blocks, played an important role in the amount of soil loss caused by water erosion. Above all, to protect the soil from erosion and maintain soil quality it is necessary to reduce the size of land blocks farmed by tenants and improve the crop rotation systems.

  17. Spark-erosion characteristics of graphite and CO gas

    International Nuclear Information System (INIS)

    Bickford, K.J.; Hanks, K.W.; Willis, W.L.

    1982-01-01

    The spark erosion characteristic of high-purity graphite and CO for 1-kHz gas blown rail-gap applications has been experimentally evaluated. The test configuration simulates a single channel, 1650-A arc discharge per linear inch of electrode length, with a 44-kV self-breakdown voltage and a transverse gas flow of 98 m/s. The dielectric gas was seeded with a small quantity of azulene vapor and a downstream uv preionization spark was used to assist the self-breakdown of the test electrodes. The erosion characteristics of other, more conventional electrode materials and dielectric gases were also examined and the results are presented graphically. Commerically pure tungsten in air was determined to exhibit the least erosion rate (2.1 x 10 -6 cc/C) for this duty, as compared to graphite and CO

  18. Surface engineering for enhanced performance against wear

    CERN Document Server

    2013-01-01

    Surface Engineering constitutes a variety of processes and sub processes. Each chapter of this work covers specific processes by experts working in the area. Included for each topic are tribological performances for each process as well as results of recent research. The reader also will benefit from in-depth studies of diffusion coatings, nanocomposite films for wear resistance, surfaces for biotribological applications, thin-film wear, tribology of thermal sprayed coatings, hardfacing, plating for tribology and high energy beam surface modifications. Material scientists as well as engineers working with surface engineering for tribology will be particularly interested in this work.

  19. The effect of microstructure on abrasive wear of steel

    Science.gov (United States)

    Kešner, A.; Chotëborský, R.; Linda, M.

    2017-09-01

    Abrasive wear of agricultural tools is one of the biggest problems in currently being. The amount of abrasive wear, depending on the microstructure, has been investigated in this work. Steels 25CrMo4 and 51CrV4 were used in this work to determine the effect of the microstructure on the abrasive wear. These steels are commonly used for components that have to withstand abrasive wear.SEM analysis was used to detect the microstructure. The standardized ASTM G65 method was used to compare the abrasive wear of steels. The results show that the abrasive wear depends on the microstructure of steels.

  20. Observed latitudinal variations in erosion as a function of glacier dynamics

    Science.gov (United States)

    Koppes, Michéle; Hallet, Bernard; Rignot, Eric; Mouginot, Jérémie; Wellner, Julia Smith; Boldt, Katherine

    2015-10-01

    Glacial erosion is fundamental to our understanding of the role of Cenozoic-era climate change in the development of topography worldwide, yet the factors that control the rate of erosion by ice remain poorly understood. In many tectonically active mountain ranges, glaciers have been inferred to be highly erosive, and conditions of glaciation are used to explain both the marked relief typical of alpine settings and the limit on mountain heights above the snowline, that is, the glacial buzzsaw. In other high-latitude regions, glacial erosion is presumed to be minimal, where a mantle of cold ice effectively protects landscapes from erosion. Glacial erosion rates are expected to increase with decreasing latitude, owing to the climatic control on basal temperature and the production of meltwater, which promotes glacial sliding, erosion and sediment transfer. This relationship between climate, glacier dynamics and erosion rate is the focus of recent numerical modelling, yet it is qualitative and lacks an empirical database. Here we present a comprehensive data set that permits explicit examination of the factors controlling glacier erosion across climatic regimes. We report contemporary ice fluxes, sliding speeds and erosion rates inferred from sediment yields from 15 outlet glaciers spanning 19 degrees of latitude from Patagonia to the Antarctic Peninsula. Although this broad region has a relatively uniform tectonic and geologic history, the thermal regimes of its glaciers range from temperate to polar. We find that basin-averaged erosion rates vary by three orders of magnitude over this latitudinal transect. Our findings imply that climate and the glacier thermal regime control erosion rates more than do extent of ice cover, ice flux or sliding speeds.

  1. Behavior of farmers in regard to erosion by water as reflected by their farming practices.

    Science.gov (United States)

    Auerswald, Karl; Fischer, Franziska K; Kistler, Michael; Treisch, Melanie; Maier, Harald; Brandhuber, Robert

    2018-02-01

    The interplay between natural site conditions and farming raises erosion by water above geological background levels. We examined the hypothesis that farmers take erosion into account in their farming decisions and switch to farming practices with lower erosion risk the higher the site-specific hazard becomes. Erosion since the last tillage was observed from aerial orthorectified photographs for 8100 fields belonging to 1879 farmers distributed across Bavaria (South Germany) and it was modeled by the Universal Soil Loss Equation using highly detailed input data (e.g., digital terrain model with 5×5m 2 resolution, rain data with 1×1km 2 and 5min resolution, crop and cropping method from annual field-specific data from incentive schemes). Observed and predicted soil loss correlated closely, demonstrating the accuracy of this method. The close correlation also indicted that the farmers could easily observe the degree of recent erosion on their fields, even without modelling. Farmers clearly did not consider erosion in their decisions. When natural risk increased, e.g. due to steeper slopes, they neither grew crops with lower erosion potential, nor reduced field size, nor used contouring. In addition, they did not compensate for the cultivation of crops with higher erosion potential by using conservation techniques like mulch tillage or contouring, or by reducing field size. Only subsidized measures, like mulch tillage or organic farming, were applied but only at the absolute minimum that was necessary to obtain subsidies. However, this did not achieve the reduction in erosion that would be possible if these measures had been fully applied. We conclude that subsidies may be an appropriate method of reducing erosion but the present weak supervision, which assumes that farmers themselves will take erosion into account and that subsidies are only needed to compensate for any disadvantages caused by erosion-reducing measures, is clearly not justified. Copyright © 2017

  2. Urethral Stricture Outcomes After Artificial Urinary Sphincter Cuff Erosion: Results From a Multicenter Retrospective Analysis.

    Science.gov (United States)

    Gross, Martin S; Broghammer, Joshua A; Kaufman, Melissa R; Milam, Douglas F; Brant, William O; Cleves, Mario A; Dum, Travis W; McClung, Christopher; Jones, LeRoy A; Brady, Jeffrey D; Pryor, Michael B; Henry, Gerard D

    2017-06-01

    To evaluate the influence of both repair type and degree of cuff erosion on postoperative urethral stricture rate. Sparse literature exists regarding patient outcomes after artificial urinary sphincter (AUS) cuff erosion. Surgeons from 6 high-volume male continence centers compiled a comprehensive database of post-erosion patients to examine outcomes. This retrospective multi-institution study included 80 patients treated for AUS cuff erosions. Seventy-eight patients had specific information regarding post-cuff erosion urethral strictures. Erosion patients were categorized into 1 of 3 repair types at the time of explant surgery: catheter only, single-layer capsule-to-capsule repair (urethrorrhaphy), and formal urethroplasty. Operative notes and available medical records were extensively reviewed to collect study data. Twenty-five of 78 patients manifested a urethral stricture after AUS cuff erosion (32%). More strictures occurred among patients who underwent urethrorrhaphy (40% vs 29% for catheter only and 14% for urethroplasty). Stricture rates did not vary significantly by repair type (P = .2). Strictures occurred significantly more frequently in patients with complete cuff erosions (58%) as compared to partial erosions (25%, P = .037). A trend was detected regarding increased percentage of erosion correlating with increased stricture rate, but this did not reach statistical significance (P = .057). Partially eroded patients were more likely to undergo urethrorrhaphy repair (60%, P = .002). Urethral stricture was more likely to occur after complete cuff erosion as opposed to partial erosion in this multicenter retrospective population. Repair type, whether catheter only, urethrorrhaphy, or formal urethroplasty, did not appear to influence postoperative stricture rate. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Effects of Load and Speed on Wear Rate of Abrasive Wear for 2014 Al Alloy

    Science.gov (United States)

    Odabas, D.

    2018-01-01

    In this paper, the effects of the normal load and sliding speed on wear rate of two-body abrasive wear for 2014 Al Alloy were investigated in detail. In order to understand the variation in wear behaviour with load and speed, wear tests were carried out at a sliding distance of 11 m, a speed of 0.36 m/s, a duration of 30 s and loads in the range 3-11 N using 220 grit abrasive paper, and at a speed range 0.09-0.90 m/s, a load of 5 N and an average sliding distance of 11 m using abrasive papers of 150 grit size under dry friction conditions. Before the wear tests, solution treatment of the 2014 Al alloy was carried out at temperatures of 505 and 520 °C for 1 h in a muffle furnace and then quenched in cold water at 15 °C. Later, the ageing treatment was carried out at 185 °C for 8 h in the furnace. Generally, wear rate due to time increased linearly and linear wear resistance decreased with increasing loads. However, the wear rate was directly proportional to the load up to a critical load of 7 N. After this load, the slope of the curves decreased because the excessive deformation of the worn surface and the instability of the abrasive grains began to increase. When the load on an abrasive grain reaches a critical value, the groove width is about 0.17 of the abrasive grain diameter, and the abrasive grains begin to fail. The wear rate due to time increased slightly as the sliding speed increased in the range 0.09-0.90 m/s. The reason for this is that changes arising from strain rate and friction heating are expected with increasing sliding speeds.

  4. The Arctic Coastal Erosion Problem

    Energy Technology Data Exchange (ETDEWEB)

    Frederick, Jennifer M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Thomas, Matthew Anthony [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bull, Diana L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jones, Craig A. [Integral Consulting Inc., San Francisco, CA (United States); Roberts, Jesse D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-09-01

    Permafrost-dominated coastlines in the Arctic are rapidly disappearing. Arctic coastal erosion rates in the United States have doubled since the middle of the twentieth century and appear to be accelerating. Positive erosion trends have been observed for highly-variable geomorphic conditions across the entire Arctic, suggesting a major (human-timescale) shift in coastal landscape evolution. Unfortunately, irreversible coastal land loss in this region poses a threat to native, industrial, scientific, and military communities. The Arctic coastline is vast, spanning more than 100,000 km across eight nations, ten percent of which is overseen by the United States. Much of area is inaccessible by all-season roads. People and infrastructure, therefore, are commonly located near the coast. The impact of the Arctic coastal erosion problem is widespread. Homes are being lost. Residents are being dispersed and their villages relocated. Shoreline fuel storage and delivery systems are at greater risk. The U.S. Department of Energy (DOE) and Sandia National Laboratories (SNL) operate research facilities along some of the most rapidly eroding sections of coast in the world. The U.S. Department of Defense (DOD) is struggling to fortify coastal radar sites, operated to ensure national sovereignty in the air, against the erosion problem. Rapid alterations to the Arctic coastline are facilitated by oceanographic and geomorphic perturbations associated with climate change. Sea ice extent is declining, sea level is rising, sea water temperature is increasing, and permafrost state is changing. The polar orientation of the Arctic exacerbates the magnitude and rate of the environmental forcings that facilitate coastal land area loss. The fundamental mechanics of these processes are understood; their non-linear combination poses an extreme hazard. Tools to accurately predict Arctic coastal erosion do not exist. To obtain an accurate predictive model, a coupling of the influences of

  5. Legislative Prohibitions on wearing a headscarf: Are they justified?

    Directory of Open Access Journals (Sweden)

    Fatima Osman

    2014-11-01

    Full Text Available A headscarf, a simple piece of cloth that covers the head, is a controversial garment that carries various connotations and meanings. While it may be accepted as just another item of clothing when worn by non-Muslim women, it is often the subject of much controversy when worn by Muslim women. In recent years the headscarf has been described as a symbol of Islam's oppression of women and simultaneously of terrorism. As the debate regarding the acceptability of the headscarf in the modern world continues, an increasing number of states have legislated to ban the wearing of the headscarf. This article critically examines the reasons underlying these bans and argues that these prohibitions are not justified. It does this by first analysing the place of the headscarf in Islam, its religious basis and its significance to Muslim women. It argues that the headscarf is more than just a mere religious symbol and that Muslim women wear the headscarf as a matter of religious obligation. The headscarf is considered to be an important religious practice protected by the right to freedom of religion. Thereafter the article examines legislative bans on the headscarf in France, Turkey and Switzerland in order to identify the most popular justifications advanced by states and courts for banning the headscarf. It critically evaluates the justifications for protecting secularism, preventing coercion, promoting equality and curbing religious extremism, and disputes that the reasons put forward by states and accepted by courts justify banning the headscarf. It thereafter explores how South African courts would respond to a headscarf ban and argues that schools and employers should accommodate the headscarf. While Muslim women may not have an absolute right to wear the headscarf, there has thus far been no justifiable reason for banning the headscarf.

  6. Fretting wear behavior of zirconium alloy in B-Li water at 300 °C

    Science.gov (United States)

    Zhang, Lefu; Lai, Ping; Liu, Qingdong; Zeng, Qifeng; Lu, Junqiang; Guo, Xianglong

    2018-02-01

    The tangential fretting wear of three kinds of zirconium alloys tube mated with 304 stainless steel (SS) plate was investigated. The tests were conducted in an autoclave containing 300 °C pressurized B-Li water for tube-on-plate contact configuration. The worn surfaces were examined with scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and 3D microscopy. The cross-section of wear scar was examined with transmission electron microscope (TEM). The results indicated that the dominant wear mechanism of zirconium alloys in this test condition was delamination and oxidation. The oxide layer on the fretted area consists of outer oxide layer composed of iron oxide and zirconium oxide and inner oxide layer composed of zirconium oxide.

  7. Evaluation of radiological findings of complete gastric erosions

    International Nuclear Information System (INIS)

    Jung, Hyun Sub; Choi, See Sung; Lim, Yeo Sub; Kim, Byung Chan; Chung, Young Sun; Kim, Chang Guhn; Won, Jong Jin

    1987-01-01

    The double-contrast upper gastrointestinal (UGI) examination is an effective means of clearly demonstrating complete gastric erosions. The main radiographic feature of the complete gastric erosion is a small barium fleck surrounded by a radiolucent halo in the gastric mucosa. From Jan. 1984 to Dec. 1986 a total of 48 cases of complete gastric erosions was diagnosed by double-contrast UGI examinations, and then 12 cases among them underwent endoscopy within 6 days of UGI examination. For evaluation of the relationship of the diameters of radiolucent halos to the central barium flecks, the radiographic findings were reviewed. 1. 1) The male to female ratio was 20:28. The age of patients ranged from 15 to 76 years, and the most common age group was 6th decade. 2) The clinical symptoms included epigastralgia (63%), indigestion, hunger pain, and vomiting. 2. Thirteen coexistent diseases were found in 11 patients (22.9%): gastric ulcer in 4 patients, duodenal ulcer in 3, gastric cancer in 3, liver cirrhosis in 2, and hepatoma in one. 3. The gastric antrum was involved in all cases. The gastric body was also involved in 8 case, and duodenal bulb in 2 cases. 4. In all cases there were multiple complete erosions. The number of the erosions were 2 to 10 in 83.4% of cases. The radiographic findings of 330 complete erosions in the 48 cases were analyzed. 1) The diameters of surrounding halos varied from 3 to 11mm, and the sized of the central barium flecks from 0(No central barium fleck) to 5mm. The shapes of central barium flecks were round in 70.6% of complete erosions. 2) In general, the small central barium flecks had small surrounding halos, and the large ones large halos (correlation coefficient r=0.97). But with the enlargement of central barium flecks, the ratios of the diameters of surrounding halos to the size of central barium flecks tended to decrease by degrees. It appears that in the formation of a surrounding mucosal elevation (radiolucent halo) of a complete

  8. Sliding wear of conventional and nanostructured cemented carbides

    Energy Technology Data Exchange (ETDEWEB)

    Jia, K. [Stevens Inst. of Tech., Hoboken, NJ (United States). Dept. of Materials Science and Engineering; Fischer, T.E. [Stevens Inst. of Tech., Hoboken, NJ (United States). Dept. of Materials Science and Engineering

    1997-03-01

    The sliding wear mechanisms of cemented carbide and the effects of the microstructure scale on the wear resistance were investigated by performing a series of unlubricated sliding wear tests in air with pins of WC-Co composites sliding against silicon nitride disks. In the first approximation, the wear rate is proportional to the hardness with a wear coefficient k=6.9x10{sup -6} for all materials. In the conventional cermets, the wear coefficient k also depends on the grain size; materials with smaller WC grains exhibit a smaller wear resistance. This reduction, however, does not extend to the nanostructured materials which exhibit the above value for k: Their wear resistance is higher than that of conventional cermets in proportion to their hardness. The data can also be expressed in terms of cobalt content: The lower the cobalt content, the lower the wear; but two different such dependencies exist, one for the conventional and one for the nanostructured materials with lower wear. The sliding wear of WC-Co composites occurs on a very small scale: The worn surfaces show no evidence of fracture of plastic deformation. This wear behavior is explained by the hexagonal structure and the anisotropic mechanical behavior of the WC grains that are capable of shear in a limited number of planes but are not capable of triaxial deformation. The higher wear resistance of the nanostructured composites is related to their hardness which decreases the real area of contact. (orig.)

  9. Preventing erosion at pipeline crossings of watercourses

    International Nuclear Information System (INIS)

    Sawatsky, L.; Arnold, G.

    1997-01-01

    Watercourses are naturally vulnerable to erosion but the risk is particularly acute after sub-soil and armour materials have been disturbed by trenching and backfilling during construction. Various types of erosion (river scour, river bed, river channel bed and river bank ) and the progressive removal of pipeline cover resulting from erosion were discussed. Methods of estimating the risk of progressive erosion, river avulsions and beaver dam scour, and methods of mitigating erosion at pipeline crossings such as deep burial, proper siting, conventional armouring, and a combination of bank toe protection, and upper bank vegetation cover, were described

  10. Splash erosion. A bibliometric Review

    Science.gov (United States)

    Fernández Raga, M. B.

    2012-04-01

    Ellison (1944) developed the splash board as a system for measuring splash erosion that was both cheap and reliable. Bollinne (1975), Morgan (1978, 1981). Mutchler (1967) described another different type of splash detectors according to whether they were passive or could register data. In the study mentioned above these authors included bottles, funnels, glasses, photography, markers. After that several devices has been made up like the splash sampler (Leguedois et al., 2005), soil tray (Van Dijk et al., 2002), splash funnel (Terry, 1989) and several rain cups (Fernandez-Raga et al., 2010; Molina and Llinares, 1996; Torri et al., 1987). Splash erosion research has materialized in the form of a number of papers published in international journals. The database of bibliographic references employed has been one of the most prestigious ones: theWeb of Science (ISI). The search was carried out on January 27th 2012. Among the 3x10^8 scholarly documents included in the Science Citation Index Expanded (SCI-EXPANDED) 1899 to present , the searching engine located 439 containing the word "splash erosion*", where the asterisk acts as a wildcard for any letter or group of letters. Of these, 383 were classified as articles, 87 as proceeding papers, 5 as editorial material, 2 as notes and 1 as correction. These documents have been published in 163 different journals, although four are particularly recurrent: Earth surface processes and Landforms, Catena, Soil Science Society of America Journal and Hydrological processes, with 41, 35, 35 and 26 published documents respectively. A geographic analysis of these articles has been carried out in an attempt to determine in what parts of the world research projects were making use of splash erosion. The results are that anglo-saxon countries, as USA, England and Australia dominate, particularly USA, with 130 articles. China and Japan are large communities of researches too, and some Central European countries as Belgium, France Germany

  11. Soil Erosion Threatens Food Production

    Directory of Open Access Journals (Sweden)

    Michael Burgess

    2013-08-01

    Full Text Available Since humans worldwide obtain more than 99.7% of their food (calories from the land and less than 0.3% from the oceans and aquatic ecosystems, preserving cropland and maintaining soil fertility should be of the highest importance to human welfare. Soil erosion is one of the most serious threats facing world food production. Each year about 10 million ha of cropland are lost due to soil erosion, thus reducing the cropland available for world food production. The loss of cropland is a serious problem because the World Health Organization and the Food and Agricultural Organization report that two-thirds of the world population is malnourished. Overall, soil is being lost from agricultural areas 10 to 40 times faster than the rate of soil formation imperiling humanity’s food security.

  12. Sports drinks and dental erosion.

    Science.gov (United States)

    Noble, Warden H; Donovan, Terence E; Geissberger, Marc

    2011-04-01

    Sports drinks were originally developed to improve hydration and performance in athletes taking part in intense or endurance sporting events. These drinks contain relatively high amounts of carbohydrates (sugars), salt, and citric acid. These ingredients create the potential for dental ramifications and overall public health consequences such as obesity and diabetes. High intake of sports drinks during exercise, coupled with xerostomia from dehydration, may lead to the possibility of erosive damage to teeth.

  13. Erosive forms in rivers systems

    International Nuclear Information System (INIS)

    Una Alvarez, E. de; Vidal Romani, J. R.; Rodriguez Martinez-Conde, R.

    2009-01-01

    The purpose of this work is to analyze the geomorphological meaning of the concepts of stability/change and to study its influence on a fluvial erosion system. Different cases of fluvial potholes in Galicia (NW of the Iberian Peninsula) are considered. The work conclusions refer to the nature of the process and its morphological evolution in order to advance towards later contributions with respect of this type of systems. (Author) 14 refs.

  14. Corrosion-wear of β-Ti alloy TMZF (Ti-12Mo-6Zr-2Fe) in simulated body fluid.

    Science.gov (United States)

    Yang, Xueyuan; Hutchinson, Christopher R

    2016-09-15

    Titanium alloys are popular metallic implant materials for use in total hip replacements. Although, α+β titanium alloys such as Ti-6Al-4V have been the most commonly used alloys, the high Young's modulus (∼110GPa) leads to an undesirable stress shielding effect. An alternative is to use β titanium alloys that exhibit a significantly lower Young's modulus (∼70GPa). Femoral stems made of a β titanium alloy known as TMZF (Ti-12Mo-6Zr-2Fe (wt.%)) have been used as part of modular hip replacements since the early 2000's but these were recalled in 2011 by the US Food & Drug Administration (FDA) due to unacceptable levels of 'wear debris'. The wear was caused by small relative movement of the stem and neck at the junction where they fit together in the modular hip replacement design. In this study, the corrosion and wear properties of the TMZF alloy were investigated in simulated body fluid to identify the reason for the wear debris generation. Ti64 was used as a control for comparison. It is shown that the interaction between the surfaces of Ti64 and TMZF with simulated body fluid is very similar, both from the point of view of the products formed and the kinetics of the reaction. The dry wear behaviour of TMZF is also close to that of Ti64 and consistent with expectations based on Archard's law for abrasive wear. However, wear of Ti64 and TMZF in simulated body fluid show contrasting behaviours. A type of time-dependent wear test is used to examine the synergy between corrosion and wear of TMZF and Ti64. It is shown that the wear of TMZF accelerated rapidly in SBF whereas that of Ti64 is reduced. The critical role of the strain hardening capacity of the two materials and its role in helping the surface resist abrasion by hydroxyapatite particles formed as a result of the reaction with the SBF is discussed and recommendations are made for modifications that could be made to the TMZF alloy to improve the corrosion-wear response. TMZF is a low modulus β-Ti alloy

  15. ERRATUM: Work smart, wear your hard hat

    CERN Multimedia

    2003-01-01

    An error appeared in the article «Work smart, wear your hard hat» published in Weekly Bulletin 27/2003, page 5. The impact which pierced a hole in the hard hat worn by Gerd Fetchenhauer was the equivalent of a box weighing 5 kg and not 50 kg.

  16. Wear-Out Sensitivity Analysis Project Abstract

    Science.gov (United States)

    Harris, Adam

    2015-01-01

    During the course of the Summer 2015 internship session, I worked in the Reliability and Maintainability group of the ISS Safety and Mission Assurance department. My project was a statistical analysis of how sensitive ORU's (Orbital Replacement Units) are to a reliability parameter called the wear-out characteristic. The intended goal of this was to determine a worst case scenario of how many spares would be needed if multiple systems started exhibiting wear-out characteristics simultaneously. The goal was also to determine which parts would be most likely to do so. In order to do this, my duties were to take historical data of operational times and failure times of these ORU's and use them to build predictive models of failure using probability distribution functions, mainly the Weibull distribution. Then, I ran Monte Carlo Simulations to see how an entire population of these components would perform. From here, my final duty was to vary the wear-out characteristic from the intrinsic value, to extremely high wear-out values and determine how much the probability of sufficiency of the population would shift. This was done for around 30 different ORU populations on board the ISS.

  17. Healthy Contact Lens Wear and Care

    Centers for Disease Control (CDC) Podcasts

    2014-02-04

    In this podcast, CDC’s Dr. Jennifer Cope explains some basic steps for proper wear and care of soft contact lenses.  Created: 2/4/2014 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 2/4/2014.

  18. Clinical pulmonary function and industrial respirator wear

    Energy Technology Data Exchange (ETDEWEB)

    Raven, P.B. (Texas College of Osteopathic Medicine, Fort Worth); Moss, R.F.; Page, K.; Garmon, R.; Skaggs, B.

    1981-12-01

    This investigation was the initial step in determining a clinical pulmonary test which could be used to evaluate workers as to their suitability to industrial respirator wear. Sixty subjects, 12 superior, 37 normal, and 11 moderately impaired with respect to lung function tests were evaluated with a battery of clinical pulmonary tests while wearing an industrial respirator. The respirator was a full-face mask (MSA-Ultravue) demand breathing type equipped with an inspiratory resistance of 85mm H/sub 2/O at 85 L/min air flow and an expiratory resistance of 25mm H/sub 2/O at 85 L/min air flow. Comparisons of these tests were made between the three groups of subjects both with and without a respirator. It appears that those lung tests which measure the flow characteristics of the lung especially those that are effort dependant are more susceptible to change as a result of respirator wear. Hence, the respirator affects the person with superior lung function to a greater degree than the moderately impaired person. It was suggested that the clinical test of 15 second maximum voluntary ventilations (MVV./sub 25/) may be the test of choice for determining worker capability in wearing an industrial respirator.

  19. Effective tool wear estimation through multisensory information ...

    African Journals Online (AJOL)

    On-line tool wear monitoring plays a significant role in industrial automation for higher productivity and product quality. In addition, an intelligent system is required to make a timely decision for tool change in machining systems in order to avoid the subsequent consequences on the dimensional accuracy and surface finish ...

  20. Tribology: Friction, lubrication, and wear technology

    Science.gov (United States)

    Blau, Peter J.

    1993-01-01

    The topics are presented in viewgraph form and include the following: introduction and definitions of terms; friction concepts; lubrication technology concepts; wear technology concepts; and tribological transitions. This document is designed for educators who seek to teach these concepts to their students.

  1. Lubrication And Wear Of Hot Ceramics

    Science.gov (United States)

    Sliney, H. E.; Jacobson, T. P.; Deadmore, D.; Miyoshi, K.

    1988-01-01

    Report presents results of experiments on tribological properties of ceramics. Describes friction and wear characteristics of some ceramics under consideration for use in gas turbines, diesel engines, and Stirling engines. Discusses formulation of composite plasma-sprayed ceramics containing solid lubricant additives, and data for carbide- and oxide-based composite coatings for use at temperatures up to at least 900 degree C.

  2. The effect of human saliva substitutes in an erosion-abrasion cycling model.

    Science.gov (United States)

    Hara, Anderson T; González-Cabezas, Carlos; Creeth, Jonathan; Zero, Domenick T

    2008-12-01

    Saliva may affect dental erosion-abrasion by reducing demineralization, enhancing remineralization, and acting as lubricant. This study tested the effect of human saliva substitutes in an erosion-abrasion cycling model designed for enamel and root dentin. Specimens were randomly assigned into the following groups (n = 8): artificial saliva (AS), artificial saliva + mucin (AS+M), deionized water (DIW, negative control), and pooled human saliva (HS, clinical reference). Each group was submitted to a cycle of 5 min in 1% citric acid (pH 3.75), 30 min in the testing solutions, and toothbrushing (enamel, 500 strokes; dentin, 150 strokes, approximately 200 g load) in fluoridated dentifrice (1,100 p.p.m. NaF) slurry. Specimens were rinsed and dried after each procedure. This cycle was repeated three times each day, for 3 d. Substrate loss was measured daily using optical profilometry. Analysis of variance (anova) and Tukey tests (alpha=0.05) showed a significant increase in enamel and dentin wear throughout the experiment for all groups. At the end of the experiment, enamel wear for each group was ranked as: (AS)<(AS+M) and (HS)<(DIW), with AS+M not differing from HS. For dentin, groups AS and AS+M did not differ from each other or from DIW, but showed significantly higher wear than HS. The artificial saliva with mucin showed promise as a potential substitute for human saliva in the enamel erosion-abrasion cycling model. For dentin, none of the artificial salivas performed similarly to human saliva.

  3. Soil cover and wind erosion

    Energy Technology Data Exchange (ETDEWEB)

    Fryrear, D.W.

    Wind erosion on agricultural lands can be reduced if the soil surface is protected with crop residues. In evaluating the influence of residues on wind erosion, previous research has expressed residues of various crops as an equivalent of flat, small grain. This becomes difficult as the density of the residue changes with weathering, or as crops other than the major cultivated crops are grown. Soil losses due to wind erosion were determined by covering various percentages of the soil surface with simulated flat residues (wood dowels 3.1 to 25.4 mm in diameter). Covering 20% of the soil surface reduced soil losses 57%, and a 50% cover reduced soil losses 95%. The expression SLR = 1.81 e/sup x/ where x = /sup -0.072% SC/ describes the relationship between soil loss ratio (SLR) and percent soil cover (% SC) with a correlation coefficient of -0.94 (soil cover limits 8 to 80%). The cover can be any nonerodible material such as large clods, gravel, cotton gin trash, or any diameter stick between 3.1 and 25.4 mm. Percent soil cover is easily measured in the field or can be estimated with a minimum of training and experience.

  4. Micromechanisms of friction and wear introduction to relativistic tribology

    CERN Document Server

    Lyubimov, Dmitrij; Pinchuk, Leonid

    2013-01-01

    The modern vision of the micromechanism of friction and wear is explored, from the examination of ideal and real crystal structure and adhesion properties to the dynamics of solid frictional interaction. The fundamental quantum-mechanical and relativity principles of particle interaction are considered as basis of friction micro-process examination. The changes in solid structure originated from the influence of different kinds of force fields are considered. The principal possibility of relativity effect manifestation by friction is explained. The critical state of friction – triboplasma – was studied. Structural peculiarities of triboplasma, the kinetics of its transformation during frictional interaction as well as the influence of plasma and postplasma processes on tribojunction friction characteristics and complex formation by friction were examined. The book addresses to tribology researchers.

  5. Comparison of two measurement techniques for clinical wear

    DEFF Research Database (Denmark)

    Peters, M C; Delong, R; Pintado, M R

    1999-01-01

    Clinical wear of restorations is generally evaluated by marginal integrity over time. In this study, both a subjective and an objective method for wear assessment are compared, and the relative advantages and disadvantages of each are considered....

  6. Is tooth wear in the primary dentition predictive of tooth wear in the permanent dentition? Report from a longitudinal study.

    Science.gov (United States)

    Harding, M A; Whelton, H P; Shirodaria, S C; O'Mullane, D M; Cronin, M S

    2010-03-01

    To determine the prevalence of tooth wear in the permanent dentition of a sample of 12-year-old school children and establish whether an association exists between tooth wear recorded now and tooth wear recorded in their primary dentition at age five. A prospective cohort study. At follow-up to a previous study complete data were available for 123 children; fieldwork was conducted in the child's primary school. Measurement of tooth wear used a scoring system modified from the Smith and Knight Tooth Wear Index (TWI). Tooth wear which had progressed to dentine was assessed on the occlusal surfaces of the four first permanent molars, the labial, lingual/palatal and incisal surfaces of the six upper and six lower anterior teeth; a total of 40 scoreable surfaces. Demographic data were collected from the parents, and a questionnaire on oral hygiene habits, diet and behaviours was completed by each child. In total 38% (n = 47) of subjects had tooth wear, if incisor teeth only were included, 33% (n = 40) had tooth wear and similarly if the occlusal surfaces of molar teeth only were included 10% (n = 12) had signs of tooth wear. Gender was significantly associated with tooth wear: males had more tooth wear. The presence of tooth wear with dentine exposed in the primary dentition was significantly associated with tooth wear on the occlusal surfaces of the first permanent molars. Males had more tooth wear than females. An association existed between tooth wear recorded at age 5 and molar tooth wear recorded at age 12. Tooth wear is a lifelong cumulative process and should be recorded in both the primary and permanent dentitions.

  7. Effect of natural gel product on bovine dentin erosion in vitro

    Directory of Open Access Journals (Sweden)

    Andre de Carvalho SALES-PERES

    2013-12-01

    Full Text Available Objective: To evaluate the efficacy of Neem (Azadirachta indica experimental gel for the prevention of erosive wear on bovine dentin, in vitro. Material and Methods: One hundred dentin blocks were allocated into 5 experimental groups (20 samples each: C (control group, without gel; CG (control group, only base gel; F (fluoride gel, 1.23% NaF; pH 4.1, Dentsply; Brazil; N (Neem gel, 10% neem extract; pH 4.1, manipulation; NF (Neem+fluoride gel, 10% Neem extract and 1.23% NaF; pH 4.1, manipulation. The blocks were stored in artificial saliva for 24 hours. After this, they were submitted to six alternating re- and demineralization cycles. The blocks were analyzed for wear (profilometry. The results were submitted to statistical analysis by ANOVA and Tukey tests (P<0.05. Results: The mean wear (±SD, µm was shown as follows in groups: C (13.09±0.99, CG (10.60±1.99, F (10.90±1.44, N (12.68±1.13 and NF (10.84±1.65. All gels showed some preventive action when compared with control group. However, significant differences were found only between Neem+fluoride gel and fluoride gel. Conclusion: A single application of a neem-containing fluoride gel reduced dentin erosion, thus it is a possible alternative in reducing dental wear. Further research should investigate the action mechanism and the synergism between them.

  8. Corrosive wear. Evaluation of wear and corrosive resistant materials; Noetningskorrosion. Utvaerdering av noetnings- och korrosionsbestaendiga material

    Energy Technology Data Exchange (ETDEWEB)

    Persson, H.; Hjertsen, D.; Waara, P.; Prakash, B.; Hardell, J.

    2007-12-15

    With a new purchase of a waste conveyer screw at hand, for the 'A-warehouse' at the combined power and heating plant at E.ON Norrkoeping, the request for improved construction materials was raised. The previous screw required maintenance with very short intervals due to the difficult operation conditions. With the new screw the expectation is to manage 6 months of operation without interruption. The environment for the screw has two main components that sets the demand on the materials, on one hand the corrosive products that comes along and which forms at digestion of the waste and on the other hand the abrasive content in the waste. The term of the mechanism is wear-corrosion and can give considerably higher material loss than the two mechanisms wear and corrosion separately. Combination of a strong corrosive environment together with extensive wear is something that we today have limited knowledge about. The overall objective of the project has been to establish better wear and corrosive resistant construction materials for a waste conveyer screw that will lead to reduced operational disturbance costs. The evaluation has been performed in both controlled laboratory environments and in field tests, which has given us a better understanding of what materials are more suitable in this tough environment and has given us a tool for future predictions of the wear rate of the different material. The new conveyer screw, installed in February 2007 and with which the field test have been performed, has considerably reduced the wear of the construction and the target of 6 month maintenance-free operation is met with this screw for all the evaluated materials. The wear along the screw varies very much and with a clear trend for all the materials to increase towards the feeding direction of the screw. As an example, the wear plate SS2377 (stainless duplex steel) has a useful life at the most affected areas that is calculated to be 1077 days of operation with the

  9. Improving of wear resistance of alloys with metastable austenite structure in abrasion wearing

    International Nuclear Information System (INIS)

    Popov, V.S.; Brykov, N.N.; Pugachev, G.A.

    1979-01-01

    The effect of grain composition of abrasive masses upon the wear resistance of alloys having a metastable austenitic structure is studied. The investigations have been carried out on Kh12F1 steel, using diffraction and hardness measurements and the metallographic analysis. Experimental data indicate that the specific wear of the stable alloys increases substantially with the size of abrasive particles. As regards the metastable alloys, the increase in the size of the abrasive grains has little effect upon the specific wear, as the increasing abradability of the grains is compensated for by the strengthening of the rubbing surfaces, this resulting from the ability of the metal surface layer to underao structure transformations in the course of wear

  10. Cladding of Cr- Modified NiAl Coating on 310 Stainless Steel Weld Cladding and Evaluation of its Wear Behavior.

    Directory of Open Access Journals (Sweden)

    S. Pourmohamadi

    2017-02-01

    Full Text Available In this study, a Cr-modified NiAl coating was fabricated by weld cladding technique using Gas- Tungsten Arc Welding (GTAW process on 310 steel. Chemical composition and microstructure of the coating was studied by X-Ray Diffraction (XRD, optical microscopy and scanning electron microscopy equipped with an Energy Dispersive Spectroscopy (EDS. The wear behavior of the coated steel was examined through pin-on-disc tests at ambient temperature and 400 °C. The results showed that the hardness of coated steel increased remarkably due to the formation of Cr-modified NiAl on the surface. Furthermore, the wear experiments showed that the presence of Cr-modified NiAl coating caused significant improvement in wear resistance of cladding 310 steel at both ambient temperature and 400 °C. These results were discussed based on the wear mechanism obtained from examination of the worn surfaces using SEM.

  11. A panorama of tooth wear during the medieval period.

    Science.gov (United States)

    Esclassan, Rémi; Hadjouis, Djillali; Donat, Richard; Passarrius, Olivier; Maret, Delphine; Vaysse, Frédéric; Crubézy, Eric

    2015-01-01

    Tooth wear is a natural phenomenon and a universal occurrence that has existed from the origin of humankind and depends on the way of life, especially diet. Tooth wear was very serious in ancient populations up to the medieval period. The aim of this paper is to present a global view of tooth wear in medieval times in Europe through different parameters: scoring systems, quantity and direction of wear, gender, differences between maxilla and mandible, relations with diet, caries, tooth malpositions and age.

  12. Mechanical and abrasive wear characterization of bidirectional and chopped E-glass fiber reinforced composite materials

    International Nuclear Information System (INIS)

    Siddhartha,; Gupta, Kuldeep

    2012-01-01

    Highlights: ► Bi-directional and chopped E-glass fiber reinforced epoxy composites are fabricated. ► Three body abrasive wear behavior of fabricated composites has been assessed. ► Results are validated against existing microscopic models of Lancaster and Wang. ► Tensile strength of bi-directional E-glass fiber reinforced composites increases. ► Chopped glass fiber composites are found better in abrasive wear situations. -- Abstract: Bi-directional and chopped E-glass fiber reinforced epoxy composites are fabricated in five different (15, 20, 25, 30 and 35) wt% in an epoxy resin matrix. The mechanical characterization of these composites is performed. The three body abrasive wear behavior of fabricated composites has been assessed under different operating conditions. Abrasive wear characteristics of these composites are successfully analysed using Taguchi’s experimental design scheme and analysis of variance (ANOVA). The results obtained from these experiments are also validated against existing microscopic models of Ratner-Lancaster and Wang. It is observed that quite good linear relationships is held between specific wear rate and reciprocal of ultimate strength and strain at tensile fracture of these composites which is an indicative that the experimental results are in fair agreement with these existing models. Out of all composites fabricated it is found that tensile strength of bi-directional E-glass fiber reinforced composites increases because of interface strength enhancement. Chopped glass fiber reinforced composites are observed to perform better than bi-directional glass fiber reinforced composites under abrasive wear situations. The morphology of worn composite specimens has been examined by scanning electron microscopy (SEM) to understand about dominant wear mechanisms.

  13. The behaviour of composites, glass ionomers and compomers in erosive conditions – in vitro study

    Directory of Open Access Journals (Sweden)

    Borş Andreea

    2014-10-01

    Full Text Available Objective: The aim of this in vitro study was to evaluate the influence of erosive conditions on the wear resistance of aesthetic direct restorative materials. Methods: Six dental filling materials were tested: two composites (Filtek Z550 and X-tra fil, two compomers (Dyract Extra and Twinky Star and two glass ionomers (Ketac Molar and Fuji II LC. Twenty disks (10mm×2mm of each material were prepared (n=120 and kept in artificial saliva at 37˚C for 24 hours. Specimens were cycled in acidic soft drink (Coca-Cola 5×/day, for 5’, over 30 days. Initial surface roughness ISR (Ra-μm and final surface roughness FSR were measured using a profilometer. The wear rate was calculated as difference of final minus the initial roughness (ΔSR=FSR-ISR. For statistical analysis t-test and one-way ANOVA test were used by GraphPad Prism version 5.03 statistical software. The level of significance was set at p<0.05. Results: The erosive wear rates (mean±SD, μm after exposure to acidic beverage were: 0.30±0.03 (Ketac Molar, 0.28±0.04 (Fuji II LC, 0.27±0.00 (Filtek Z550, 0.23±0.01 (X-tra fil, 0.20±0.00 (Twinky Star and 0.14±0.01 Dyract Extra, respectively. There were significant differences between the tested materials (p<0.05. Conclusions: Dental filling materials had different behaviour under the same erosive condition, however all investigated aesthetic restorative materials showed surface degradation. These findings suggest that erosive wear resistance of tooth coloured restoratives could influence their longevity in intraoral acidic conditions. Acknowledgements: The study was supported by the Internal Research Grant no. 5/30.01.2013 of the University of Medicine and Pharmacy of Tirgu Mureş.

  14. Prevalence and severity of dental erosion among jeep battery manufacturing workers at Metagalli, Mysore: A cross-sectional study

    Directory of Open Access Journals (Sweden)

    Jyothi Chavan

    2017-01-01

    Full Text Available Introduction: Majority of people employed in various industries are exposed to hazardous environment. Exposure to chemical agents in the workplace can result in adverse effects on workers. This exposure deteriorates the general and oral health of people, working in industries for long hours. Aim: The aim is to assess the prevalence and severity of dental erosion among battery manufacturing factory workers at Metagalli, Mysore, Karnataka, India. Materials and Methods: A total of 175 jeep battery manufacturing factory workers were enrolled and divided into study and comparison groups based on acid exposure. Demographic details of workers were recorded. Severity of dental erosion was calculated using Smith and Knight tooth wear index. The data were analyzed using Statistical Package for the Social Sciences version 17.0 software. Chi-square test was used to compare the categorical variables. Results: The prevalence of dental erosion among the jeep battery manufacturing factory workers was 80%. Majority of the participants in the study group had severe degree of dental erosion (scores of 3 and 4 when compared to the comparison group. Conclusion: Dental erosion was more prevalent among the jeep battery manufacturing factory workers. Study participants were the more affected group with dental erosion when compared to comparison group.

  15. Comparison of erosion and erosion control works in Macedonia, Serbia and Bulgaria

    Directory of Open Access Journals (Sweden)

    Ivan Blinkov

    2013-12-01

    Natural conditions in the Balkan countries contribute to the appearance of various erosion forms and the intensity of the erosion processes. Over the history of these countries, people who settled this region used the available natural resources to fill their needs (tree cutting, incorrect plugging, overgrazing, which contributed to soil erosion. Organized erosion control works in the Balkans started in the beginning of the 20th century (1905 in Bulgaria. The highest intensity of erosion control works were carried out during the period 1945 – 1990. Various erosion control works were launched. Bulgaria had a large anti-erosion afforestation, almost 1 million ha. Bulgaria's ecological river restoration approach has been in use for almost 50 years. Serbia contributed significant erosion and torrent control works on hilly agricultural areas. Specific screen barrages and afforestation on extremely dry areas are characteristic in Macedonia. A common characteristic for all countries is a high decrease in erosion control works in the last 20 years.

  16. Wear behavior of diamond wheel for grinding optical connector ferrule - FEA and wear test -

    International Nuclear Information System (INIS)

    Suh, Chang Min; Bae, Kyo Seouk; Suh, Min Soo

    2008-01-01

    The grinding characteristics and the wear behavior of diamond wheel for grinding the optical connector ferrule were investigated by finite element analysis (FEA) and wear test. FEA of contact between diamond wheel and ferrule shows that the subsurface damage area of ferrule is 13μm from the interface of abrasive particle and matrix. Fallout of abrasive particle is affected by the stress state at the interface. A 2-D finite element model was established to calculate the distribution of stress at the interface. As the result of FEA, fallout condition of abrasive was concerned with the ratio of the critical protrusion: the ratio of particle size is about 0.6. FE model was established to investigate the effects of the diamond concentration of wheel. The FEA result shows that the lower concentration of it has larger wear volume due to the small stress propagation. To investigate grinding performance, the pin-on-disc wear test was carried out for three types of concentrations 75%, 100% and 125%. Through the wear test, it was confirmed that the 75% wheel concentration has the highest amount of wear volume. This result shows good agreement with that of FEA. And 100% concentration by considering the grinding ratio of the wheel shows the best optimized result for the grinding performance

  17. Wear Analysis of Top Piston Ring to Reduce Top Ring Reversal Bore Wear

    Directory of Open Access Journals (Sweden)

    P. Ilanthirayan

    2017-12-01

    Full Text Available The piston rings are the most important part in engine which controls the lubricating oil consumption and blowby of the gases. The lubricating film of oil is provided to seal of gases towards crankcase and also to give smooth friction free translatory motion between rings and liner. Of the three rings present top ring is more crucial as it does the main work of restricting gases downwards the crankcase. Boundary lubrication is present at the Top dead centre (TDC and Bottom dead centre (BDC of the liner surface. In addition to this, top ring is exposed to high temperature gases which makes the oil present near the top ring to get evaporated and decreasing its viscosity, making metal-metal contact most of the time. Due to this at TDC, excess wear happens on the liner which is termed as Top ring reversal bore wear. The wear rate depends upon many parameters such as lubrication condition, viscosity index, contact type, normal forces acting on ring, geometry of ring face, surface roughness, material property. The present work explores the wear depth for different geometries of barrel ring using Finite Element model with the help of Archard wear law and the same is validated through experimentation. The study reveals that Asymmetric barrel rings have less contact pressure which in turn reduces the wear at Top dead centre.

  18. Measurement and Evaluation of Wear Frogs Switches ŽSR

    Directory of Open Access Journals (Sweden)

    Urda Ján

    2014-05-01

    Full Text Available This paper deals with the measurement and evaluation of wear frogs switches ZSR. One of the main problems is the oversize wear. The possibilities analysis of this problem is offered through a set of switches and monitoring of selected parameters. One of these parameters is also monitoring the vertical wear

  19. Assessment of the progression of tooth wear on dental casts

    NARCIS (Netherlands)

    Vervoorn-Vis, G.M.G.J.; Wetselaar, P.; Koutris, M.; Visscher, C.M.; Evälahti, M.; Ahlberg, J.; Lobbezoo, F.

    2015-01-01

    Many methods are available for the grading of tooth wear, but their ability to assess the progression of wear over time has not been studied frequently. The aim was to assess whether the occlusal/incisal grading scale of the Tooth Wear Evaluation System (TWES) was sensitive enough for the detection

  20. The influence of abrasive body dimensions on single asperity wear

    NARCIS (Netherlands)

    Woldman, M.; van der Heide, Emile; Tinga, Tiedo; Masen, Marc Arthur

    2013-01-01

    This work focuses on the relation between the properties of abrasive bodies and the wear they cause. By performing single asperity scratch tests to simulate abrasive wear, the wear process takes place in a controlled environment, allowing the properties of the abrasive body to be isolated and

  1. Wear Behavior of an Ultra-High-Strength Eutectoid Steel

    Science.gov (United States)

    Mishra, Alok; Maity, Joydeep

    2018-02-01

    Wear behavior of an ultra-high-strength AISI 1080 steel developed through incomplete austenitization-based combined cyclic heat treatment is investigated in comparison with annealed and conventional hardened and tempered conditions against an alumina disk (sliding speed = 1 m s-1) using a pin-on-disk tribometer at a load range of 7.35-14.7 N. On a gross scale, the mechanism of surface damage involves adhesive wear coupled with abrasive wear (microcutting effects in particular) at lower loads. At higher loads, mainly the abrasive wear (both microcutting and microploughing mechanisms) and evolution of adherent oxide are observed. Besides, microhardness of matrix increases with load indicating substantial strain hardening during wear test. The rate of overall wear is found to increase with load. As-received annealed steel with the lowest initial hardness suffers from severe abrasive wear, thereby exhibiting the highest wear loss. Such a severe wear loss is not observed in conventional hardened and tempered and combined cyclic heat treatment conditions. Combined cyclic heat-treated steel exhibits the greatest wear resistance (lowest wear loss) due to its initial high hardness and evolution of hard abrasion-resistant tribolayer during wear test at higher load.

  2. Effect of ageing treatment on wear properties and electrical ...

    Indian Academy of Sciences (India)

    ... was in Cu–Cr–Zr alloy aged at 500°C for 2 h and the most wear loss was in specimens aged at 530°C for 2 h. Furthermore, it was observed that the friction coefficient values resulting from wear rate were overlapped with hardness results and there is a decrease tendency of friction coefficient as wear distance increases.

  3. Severe tooth wear: European consensus statement on management guidelines

    DEFF Research Database (Denmark)

    Loomans, Bas AC; Opdam, Niek JM; Attin, Thomas

    2017-01-01

    This paper reports a European expert consensus statement on guidelines for the management of severe tooth wear. It focuses on the definition of physiological versus pathological tooth wear and recommends diagnosis, monitoring and counseling to define the activity of the wear. Restorative interven...

  4. AN EXPERIMENTAL RESEARCH ON THE WEAR OF TRUCK TIRE

    Directory of Open Access Journals (Sweden)

    Rosen IVANOV

    2015-12-01

    Full Text Available Summary. An experimental device and methodology for tire wear investigation are presented. An indirect method for wear evaluating is used. The experimental results in cases of straight motion with and without side slip are obtained. The distribution of wearing on tread pattern wide is evaluated in different running conditions.

  5. Friction and wear characteristics of carbon steels in vacuum

    Science.gov (United States)

    Verkin, B. I.; Lyubarskiy, I. M.; Udovenko, V. F.; Guslyakov, A. A.

    1974-01-01

    The nature of carbon steel friction and wear under vacuum conditions is described within the framework of general friction and wear theory. Friction is considered a dynamic process and wear is considered to be the result of a continuous sequence of transitions of the friction surface material from one state into another.

  6. Wear of control rod cluster assemblies and of instrumentation thimbles: first results obtained with the vibrateau wear simulator

    International Nuclear Information System (INIS)

    Zbinden, M.; Hersant, D.

    1993-07-01

    Several REP components are affected by a particular sort of damage called impact/sliding wear. This kind of wear, originating from flow induced vibrations, affects loosely supported tubular structures. The main involved components are: - the RCCAs claddings and the guides tubes, - the instrumentation thimbles, - the fuel rods claddings, - the SG tubes. The R and D Division is concerned with studies aiming to understand and to master the phenomena leading to this wear. The MTC Branch is charged of the study of the wear itself. Tests are carried out on wear rigs to understand and to model wear mechanisms. The following work is related to the two first wear tests campaigns on the VIBRATEAU wear simulator: - a reproducibility test series in order to assess the spreading of the experimental results, - a comparative test series on surface treatments used to improve the components war resistance. (authors). 7 figs., 2 tabs., 4 refs

  7. Mapping monthly rainfall erosivity in Europe

    DEFF Research Database (Denmark)

    Ballabio, C; Meusburger, K; Klik, A

    2017-01-01

    Rainfall erosivity as a dynamic factor of soil loss by water erosion is modelled intra-annually for the first time at European scale. The development of Rainfall Erosivity Database at European Scale (REDES) and its 2015 update with the extension to monthly component allowed to develop monthly and...... events. Consequently, spatio-temporal mapping of rainfall erosivity permits to identify the months and the areas with highest risk of soil loss where conservation measures should be applied in different seasons of the year....... and seasonal R-factor maps and assess rainfall erosivity both spatially and temporally. During winter months, significant rainfall erosivity is present only in part of the Mediterranean countries. A sudden increase of erosivity occurs in major part of European Union (except Mediterranean basin, western part...... to Eastern Europe. The maps also show a clear delineation of areas with different erosivity seasonal patterns, whose spatial outline was evidenced by cluster analysis. The monthly erosivity maps can be used to develop composite indicators that map both intra-annual variability and concentration of erosive...

  8. Validating and improving interrill erosion equations.

    Science.gov (United States)

    Zhang, Feng-Bao; Wang, Zhan-Li; Yang, Ming-Yi

    2014-01-01

    Existing interrill erosion equations based on mini-plot experiments have largely ignored the effects of slope length and plot size on interrill erosion rate. This paper describes a series of simulated rainfall experiments which were conducted according to a randomized factorial design for five slope lengths (0.4, 0.8, 1.2, 1.6, and 2 m) at a width of 0.4 m, five slope gradients (17%, 27%, 36%, 47%, and 58%), and five rainfall intensities (48, 62.4, 102, 149, and 170 mm h(-1)) to perform a systematic validation of existing interrill erosion equations based on mini-plots. The results indicated that the existing interrill erosion equations do not adequately describe the relationships between interrill erosion rate and its influencing factors with increasing slope length and rainfall intensity. Univariate analysis of variance showed that runoff rate, rainfall intensity, slope gradient, and slope length had significant effects on interrill erosion rate and that their interactions were significant at p = 0.01. An improved interrill erosion equation was constructed by analyzing the relationships of sediment concentration with rainfall intensity, slope length, and slope gradient. In the improved interrill erosion equation, the runoff rate and slope factor are the same as in the interrill erosion equation in the Water Erosion Prediction Project (WEPP), with the weight of rainfall intensity adjusted by an exponent of 0.22 and a slope length term added with an exponent of -0.25. Using experimental data from WEPP cropland soil field interrill erodibility experiments, it has been shown that the improved interrill erosion equation describes the relationship between interrill erosion rate and runoff rate, rainfall intensity, slope gradient, and slope length reasonably well and better than existing interrill erosion equations.

  9. Validating and Improving Interrill Erosion Equations

    Science.gov (United States)

    Zhang, Feng-Bao; Wang, Zhan-Li; Yang, Ming-Yi

    2014-01-01

    Existing interrill erosion equations based on mini-plot experiments have largely ignored the effects of slope length and plot size on interrill erosion rate. This paper describes a series of simulated rainfall experiments which were conducted according to a randomized factorial design for five slope lengths (0.4, 0.8, 1.2, 1.6, and 2 m) at a width of 0.4 m, five slope gradients (17%, 27%, 36%, 47%, and 58%), and five rainfall intensities (48, 62.4, 102, 149, and 170 mm h−1) to perform a systematic validation of existing interrill erosion equations based on mini-plots. The results indicated that the existing interrill erosion equations do not adequately describe the relationships between interrill erosion rate and its influencing factors with increasing slope length and rainfall intensity. Univariate analysis of variance showed that runoff rate, rainfall intensity, slope gradient, and slope length had significant effects on interrill erosion rate and that their interactions were significant at p = 0.01. An improved interrill erosion equation was constructed by analyzing the relationships of sediment concentration with rainfall intensity, slope length, and slope gradient. In the improved interrill erosion equation, the runoff rate and slope factor are the same as in the interrill erosion equation in the Water Erosion Prediction Project (WEPP), with the weight of rainfall intensity adjusted by an exponent of 0.22 and a slope length term added with an exponent of −0.25. Using experimental data from WEPP cropland soil field interrill erodibility experiments, it has been shown that the improved interrill erosion equation describes the relationship between interrill erosion rate and runoff rate, rainfall intensity, slope gradient, and slope length reasonably well and better than existing interrill erosion equations. PMID:24516624

  10. Cosmic Ray Exposure Ages of Stony Meteorites: Space Erosion or Yarkovsky?

    Science.gov (United States)

    Rubincam, David Parry

    2014-01-01

    Space erosion from dust impacts may set upper limits on the cosmic ray exposure (CRE) ages of stony meteorites. A meteoroid orbiting within the asteroid belt is bombarded by both cosmic rays and interplanetary dust particles. Galactic cosmic rays penetrate only the first few meters of the meteoroid; deeper regions are shielded. The dust particle impacts create tiny craters on the meteoroid's surface, wearing it away by space erosion (abrasion) at a particular rate. Hence a particular point inside a meteoroid accumulates cosmic ray products only until that point wears away, limiting CRE ages. The results would apply to other regolith-free surfaces in the solar system as well, so that abrasion may set upper CRE age limits which depend on the dusty environment. Calculations based on N. Divine's dust populations and on micrometeoroid cratering indicate that stony meteoroids in circular ecliptic orbits at 2 AU will record 21Ne CRE ages of approx.176 x 10(exp 6) years if dust masses are in the range 10(exp -21) - 10(exp -3) kg. This is in broad agreement with the maximum observed CRE ages of approx. 100 x 10(exp 6) years for stones. High erosion rates in the inner solar system may limit the CRE ages of Near-Earth Asteroids (NEAs) to approx. 120 x 10(exp 6) years. If abrasion should prove to be approx. 6 times quicker than found here, then space erosion may be responsible for many of the measured CRE ages of main belt stony meteorites. In that case the CRE ages may not measure the drift time to the resonances due to the Yarkovsky effects as in the standard scenario, and that for some reason Yarkovsky is ineffective.

  11. Adhesive wear of iron chromium nickel silicon manganese molybdenum niobium alloys with duplex structure

    International Nuclear Information System (INIS)

    Lugscheider, E.; Deppe, E.; Ambroziak, A.; Melzer, A.

    1991-01-01

    Iron nickel chromium manganese silicon and iron chromium nickel manganese silicon molybdenum niobium alloys have a so-called duplex structure in a wide concentration range. This causes an excellent resistance to wear superior in the case of adhesive stress with optimized concentrations of manganese, silicon, molybdenum and niobium. The materials can be used for welded armouring structures wherever cobalt and boron-containing alloy systems are not permissible, e.g. in nuclear science. Within the framework of pre-investigations for manufacturing of filling wire electrodes, cast test pieces were set up with duplex structure, and their wear behavior was examined. (orig.) [de

  12. EFFECT OF AGING ON MECHANICAL AND WEAR PROPERTIES OF BERYL PARTICULATE REINFORCED METAL MATRIX COMPOSITES

    Directory of Open Access Journals (Sweden)

    H. N. REDDAPPA

    2014-08-01

    Full Text Available This paper describes the study of effect of aging on mechanical and wear properties of ‘hot rolled’ Al6061-10% wt. of beryl particulate reinforced composites produced by stir casting have been examined. The result shows that hardness and tensile strength of ‘90% hot rolled and aged’ composites were increased by 10.28% and 3.78% as compared to ‘hot rolled’ composites respectively. The ‘hot rolled and aged’ composite shows significant decrease in specific wear rate when compared to that of ‘hot rolled’ composites.

  13. Erosivity index of urban storms: case study of two stations of Kermanshah.

    Science.gov (United States)

    Beedle, R; Hadidi, M; Parsaeitabar, E

    2009-02-15

    Present research examine the erosivity index of precipitation Kermanshah Province, two stations belonged to west Region Water Company named old Kermanshah and new Kermanshah were used, the duration of statistical period being 13 and 19 years. Data on stations was prepared graphically and the extraction of storms was performed visually with 15 min temporal step. After descriptive data on storm was adjusted and arranged tabularly, their kinetic energies were calculated with Wischmier and Smith formula considering maximum intensity of 30 min. Next, they were placed in continuous 1-72 h rainfall groups. Resulting conclusions indicated that about 85% of storm were in 1-6 h continuations and 6 h continuations had the highest values of kinetic energy as well as of erosion index (R), but remained in very low erosion class; and old and new Kermanshah stations were placed in very low erosion class, with annual average of erosion index less than 500 MJ mm ha(-1) h(-1).

  14. Wearing the T-shirt: an exploration of the ideological underpinnings ...

    African Journals Online (AJOL)

    Wearing the T-shirt: an exploration of the ideological underpinnings of visual representations of the African body with HIV or AIDS. ... currency in relation to colonialism; 2) A matter of mor(t)ality examines the relationship between morality and the mortality of the African body; 3) The legacies endure analyses selected images ...

  15. Wear and Failure Mechanism of PTFE/SiO2/Epoxy Composites

    NARCIS (Netherlands)

    Shen, J.T.; Pei, Y.T.; De Hosson, J.Th.M.

    2016-01-01

    In this work, the wear and failure mechanism of polytetrafluoroethylene (PTFE)/SiO2/epoxy composites with a high concentration of SiO2 particles under dry sliding is examined. In the composite with 12.5 wt.% PTFE, a significant rise of the coefficient of friction (COF) appears after sliding over

  16. A Study on Abrasive Wear Behavior of Spacer Grid Materials for Nuclear Power Plant

    International Nuclear Information System (INIS)

    Park, J. M.; Kim, J. H.; Park, J. K.; Jeon, K. L.

    2010-01-01

    Spacer grid is one of the key components of a light water reactor (LWR) fuel assembly. The most important function of it is to hold the fuel rods to maintain the distance between the fuel rods inside a fuel assembly. At the reactor core in operating power plants, a fretting damage has been frequently reported between a nuclear fuel rod and its supporting spring/dimple of the fuel assemblies. This is due to a flow induced vibration (FIV), Which results from the primary coolant that rapidly passes around the fuel rod to remove the excess heat generated by the nuclear reaction. Fretting damage is generally caused by fretting wear, which includes various wear mechanisms such as an oxidative, adhesive, abrasive wear, etc., or fretting fatigue, which includes a surface or bulk fatigue. The purpose of the present work are to investigate the variation of the materials with increasing number of cycles and sliding velocity under abrasive wear test and to examine the wear mechanism at each test condition

  17. Fabrication, microstructural characterization and wear characteristics of A380 alloy-alumina composites

    KAUST Repository

    Nurani, Sheikh Jaber

    2016-03-10

    To obtain better mechanical and tribological properties than aluminium alloys aluminium is reinforced with alumina particles making aluminium metal matrix composites. In this work scrap piston A380 alloy was used as the matrix alloy. Alumina particles were added by 5%, 10% and 15% into matrix alloy respectively to form desired composites by stir casting technique. Pin on disc wear testing machine with counter surface as steel disc of hardness HRC 32 and surface roughness of 0.62 μm was used to conduct the wear test. In result composites showed superior wear resistance property over A380 alloy. The effect of load, sliding speed and sliding distance on wear behaviour were also examined in this study. Wear mechanism was identified from the worn surface. Both optical and scanning electron microscope (SEM) of the composites was performed to determine the microstructures. Optical micrograph shows grain size decreases with addition of alumina particles. EDS analysis was performed to confirm the presence of α-Al matrix, primary Si particles and intermetallic. As a general method, phase compositions were analyzed by using a scanning electron microscope (SEM) equipped with an energy dispersive spectroscopy (EDS). Optical microstructures were consistent with the SEM micrographs. © 2015 IEEE.

  18. Investigation of anti-wear performance of automobile lubricants using thin layer activation analysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Biswal, Jayashree [Isotope and Radiation Application Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Thakre, G.D. [Tribology and Combustion Division, Indian Institute of Petroleum, Dehradun 248005, Uttarakhand (India); Pant, H.J., E-mail: hjpant@barc.gov.in [Isotope and Radiation Application Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Samantray, J.S. [Isotope and Radiation Application Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Arya, P.K. [Tribology and Combustion Division, Indian Institute of Petroleum, Dehradun 248005, Uttarakhand (India); Sharma, S.C.; Gupta, A.K. [Nuclear Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2017-05-15

    An investigation was carried out to examine the anti-wear behavior of automobile lubricants using thin layer activation analysis technique. For this study disc gears made of EN 31 steel were labeled with a small amount of radioactivity by irradiating with 13 MeV proton beam from a particle accelerator. Experiments on wear rate measurement of the gear were carried out by mounting the irradiated disc gear on a twin-disc tribometer under lubricated condition. The activity loss was monitored by using a NaI(Tl) scintillation detector integrated with a multichannel analyzer. The relative remnant activity was correlated with thickness loss by generating a calibration curve. The wear measurements were carried out for four different types of lubricants, named as, L1, L2, L3 and L4. At lower load L1 and L4 were found to exhibit better anti-wear properties than L2 and L3, whereas, L4 exhibited the best anti-wear performance behavior than other three lubricants at all the loads and speeds investigated.

  19. Barriers to mask wearing for influenza-like illnesses among urban Hispanic households.

    Science.gov (United States)

    Ferng, Yu-hui; Wong-McLoughlin, Jennifer; Barrett, Angela; Currie, Leanne; Larson, Elaine

    2011-01-01

    To identify barriers to mask wearing and to examine the factors associated with the willingness to wear masks among households. We used data sources from a study assessing the impact of 3 nonpharmaceutical interventions on the rates of influenza: exit interviews; home visits with a subset of the mask group; and a focus group. Risk perception score, univariate analysis, and logistic regression were conducted to identify the characteristics and predictors of mask use. Thematic barriers to mask wearing were identified from qualitative data obtained at home visits and focus group. Respondents from the mask group, when compared with the nonmask group, demonstrated higher risk perception scores concerning influenza (maximum score: 60, means: 37.6 and 30.2, pmask wearing (maximum score: 10, means: 7.8 and 7.3, p=.043). There was no significant association between demographic, attitudinal, or knowledge variables and adherence to wearing masks. Thematic barriers were identified such as social acceptability of mask use, comfort and fit, and perception of the risk/need for masks. Face masks may not be an effective intervention for seasonal or pandemic influenza unless the risk perception of influenza is high. Dissemination of culturally appropriate mask use information by health authorities and providers must be emphasized when educating the public. © 2010 Wiley Periodicals, Inc.

  20. In Vitro Investigation of Wear of CAD/CAM Polymeric Materials Against Primary Teeth

    Directory of Open Access Journals (Sweden)

    Jae-Won Choi

    2017-12-01

    Full Text Available The aim of the study was to evaluate the effects of polymeric computer-aided design/computer-aided manufacturing CAD/CAM materials on antagonistic primary tooth wear. Five CAD/CAM polymeric materials were examined: Vipi Block Monocolor (VBM, Yamahachi polymethylmethacrylate (PMMA (YAP, Mazic Duro (MZD, Vita Enamic (ENA, and Pekkton (PEK. All of the specimens were tested in a thermomechanical loading machine with the primary canine as the antagonist (50 N, 1.2 × 105 cycles, 1.7 Hz, 5/55 °C. The wear losses of the antagonist tooth and the restorative materials were calculated using reverse modelling software and an electronic scale. VBM and ENA showed significantly higher antagonist tooth wear than PEK (p < 0.05, but there was no significant difference observed among VBM, YAP, MZD, and ENA (p > 0.05. PEK showed the largest value in both material volumetric and weight losses. In terms of material volumetric losses, there was no significant difference between all of the groups (p > 0.05. In terms of material weight losses, PEK was significantly larger than ENA (p < 0.05, but there was no significant difference between VBM, YAP, MZD, and ENA (p > 0.05. Volumetric and weight losses of materials showed similar wear behaviour. However, the wear patterns of antagonists and materials were different, especially in PEK.

  1. Influence of bioadhesive polymers on the protective effect of fluoride against erosion.

    Science.gov (United States)

    Ávila, Daniele Mara da Silva; Zanatta, Rayssa Ferreira; Scaramucci, Tais; Aoki, Idalina Vieira; Torres, Carlos Rocha Gomes; Borges, Alessandra Bühler

    2017-01-01

    This study investigated if the incorporation of the bioadhesive polymers Carbopol 980, Carboxymethyl cellulose (CMC), and Aristoflex AVC in a fluoridated solution (NaF-900ppm) would increase the solution's protective effect against enamel erosion. Enamel specimens were submitted to a 5-day de-remineralization cycling model, consisting of 2min immersions in 0.3% citric acid (6x/day), 1min treatments with the polymers (associated or not with fluoride), and 60min storage in artificial saliva. Ultrapure water was used as the negative control and a 900ppm fluoride solution as positive control. The initial Knoop microhardness (KHN1) was used to randomize the samples into groups. Another two microhardness assessments were performed after the first (KHN2) and second (KHN3) acid immersions, to determine initial erosion in the first day. The formula: %KHN alt =[(KHN3-KHN2)/KHN2]*100 was used to define the protective effect of the treatments. After the 5-day cycling, surface loss (SL, in μm) was evaluated with profilometry. Data were analyzed with 2-way ANOVA and Tukey's tests (p<0.05). For %KHN alt , the polymers alone did not reduce enamel demineralization when compared to the negative control, but Carbopol associated with NaF significantly improved its protective effect. The profilometric analysis showed that Carbopol, associated or not with NaF, exhibited the lowest SL, while CMC and Aristoflex did not exhibit a protective effect, nor were they able to improve the protection of NaF. It is concluded that Carbopol enhanced NaF's protection against initial erosion. Carbopol alone or associated with NaF was able to reduce SL after several erosive challenges. Carbopol by itself was able to reduce the erosive wear magnitude to the same extent as the sodium fluoride, therefore, is a promising agent to prevent or control enamel erosion. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Iron supplementation reduces the erosive potential of a cola drink on enamel and dentin in situ.

    Science.gov (United States)

    Kato, Melissa Thiemi; Buzalaf, Marília Afonso Rabelo

    2012-01-01

    Iron has been suggested to reduce the erosive potential of cola drinks in vitro. The aim of this study was to evaluate in situ the effect of ferrous sulfate supplementation on the inhibition of the erosion caused by a cola drink. Ten adult volunteers participated in a crossover protocol conducted in two phases of 5 days, separated by a washout period of 7 days. In each phase, they wore palatal devices containing two human enamel and two human dentin blocks. The volunteers immersed the devices for 5 min in 150 mL of cola drink (Coca-ColaTM, pH 2.6), containing ferrous sulfate (10 mmol/L) or not (control), 4 times per day. The effect of ferrous sulfate on the inhibition of erosion was evaluated by profilometry (wear). Data were analyzed by paired t tests (pcola drinks with ferrous sulfate can be a good alternative for the reduction of their erosive potential. Additional studies should be done to test if lower ferrous sulfate concentrations can also have a protective effect as well as the combination of ferrous sulfate with other ions.

  3. Dental Erosion and Its Growing Importance in Clinical Practice: From Past to Present

    Science.gov (United States)

    Johansson, Ann-Katrin; Omar, Ridwaan; Carlsson, Gunnar E.; Johansson, Anders

    2012-01-01

    Since the mid-1990s, the focus of studies on tooth wear has steadily shifted from the general condition towards the more specific area of dental erosion; equally, a shift has occurred from studies in adults to those in children and adolescents. During this time, understanding of the condition has increased greatly. This paper attempts to provide a critical overview of the development of this body of knowledge, from earlier perceptions to the present. It is accepted that dental erosion has a multifactorial background, in which individual and lifestyle factors have great significance. Notwithstanding methodological differences across studies, data from many countries confirm that dental erosion is common in children and young people, and that, when present, it progresses rapidly. That the condition, and its ramifications, warrants serious consideration in clinical dentistry, is clear. It is important for the oral healthcare team to be able to recognize its early signs and symptoms and to understand its pathogenesis. Preventive strategies are essential ingredients in the management of patients with dental erosion. When necessary, treatment aimed at correcting or improving its effects might best be of a minimally invasive nature. Still, there remains a need for further research to forge better understanding of the subject. PMID:22505907

  4. Is tooth wear in the primary dentition predictive of tooth wear in the permanent dentition? Report from a longitudinal study.

    LENUS (Irish Health Repository)

    Harding, M A

    2010-03-01

    To determine the prevalence of tooth wear in the permanent dentition of a sample of 12-year-old school children and establish whether an association exists between tooth wear recorded now and tooth wear recorded in their primary dentition at age five.

  5. Process research into metallic pipe wear of hot chamber die casting machines and methods ofincreasing wear resistance

    Science.gov (United States)

    Mukhametzyanova, G. F.; Kolesnikov, MS; Mukhametzyanov, I. R.; Astatshenko, V. I.

    2017-09-01

    The kinetics and reasons for metallic pipe wear of hot chamberzinc alloy die casting machines are established.Increasing metallic pipe wear components wear resistance is being achieved by means of die steelДИ - 22 with electroslag remelting modification and electron-beamremelting modification and after the processes of nitriding and boriding besides.

  6. Research on the effect of wear-ring clearances to the axial and radial force of a centrifugal pump

    International Nuclear Information System (INIS)

    Zhao, W G; Qi, C X; Li, Y B; He, M Y

    2013-01-01

    Varying of the wear-ring clearance not only has a distinct effect on the volumetric loss of the centrifugal pump, but also on the performance of the centrifugal pump including the axial and radial forces. Comparing with the experimental studies, numerical simulation methods have some special advantages, such as the low cost, fast and high efficiency, and convenient to get the detailed structure of the internal flow characteristics, so it has been widely used in the fluid machinery study in recent years. In order to study the effect of wear-ring clearance on the force performance of the centrifugal pump, based on the Reynolds Time-Averaged N-S equations and RNG k-ε turbulence model, a centrifugal pump with three variable styles of the wear-rings was simulated: Only the clearance of the front wear-ring was changed, only the clearance of the back wear-ring was changed and both were changed. Comparing with the experiment, numerical results show a good agreement. In the three changing styles of the clearance, the variable of the clearance of front wear-ring has the most influence on the axial force of the centrifugal pump, while has tiny effect on the radial force for all the conditions

  7. Clinical analysis of asthenopia caused by wearing inappropriate glasses in college students

    Directory of Open Access Journals (Sweden)

    Li Wang

    2015-01-01

    Full Text Available AIM: To proposed control measures by exploring visual fatigue caused by college students wearing inappropriate glasses.METHODS: A total of 124 cases of asthenopia patients underwent optometry students audition, checked the original spectacles; TOPCON-CL100 computer center was used to checked the original mirror glasses(glasses, the distance between the optical center; with near vision as the standard examination table nearly with vergence and regulation near point, and checked the visual function. RESULTS: All 124 cases(248 eyeshad refractive errors, 77% were spherical mirror and 69% column mirror with error ≥±0.50D, and the pupil center distance from the lens had significant difference(U=5.27, PCONCLUSION: Students wearing inappropriate spectacle asthenopia is caused by one of the main scientific wearing glasses can effectively control asthenopia.

  8. Analysis of Properties of Hard Coatings and Wear Resistance of Chemical Vapour Deposition (PVD Coated Technology

    Directory of Open Access Journals (Sweden)

    Pavel Hudeček

    2015-01-01

    Full Text Available Modern coating methods are having become an important part of industry. Wear resistance, durability, toughness (breakage resistance and hot hardness (high hardness and chemical stability at high temperature are the four main technological properties necessary for durability and long life time. These proprieties are for productivity, economy and ecology very important point. This resource deals with the analysis of properties of hard coatings and wear resistance of chemical vapour deposition (PVD coated technology. It focuses on the preparation, execution and evaluation of test coatings on the front ball-milling cutters. Examination of these characteristic properties may give into an insight to the reason why some systems show excellent wear characteristic.

  9. Effect of Polypropylene Modification by Impregnation with Oil on Its Wear and Friction Coefficient at Variable Load and Various Friction Rates

    Directory of Open Access Journals (Sweden)

    Paweł Sędłak

    2017-01-01

    Full Text Available Laboratorial two-body wear testing was carried out in order to assess effects of polypropylene modification by impregnating it with oils on friction coefficient and wear in comparison to those parameters of unmodified polypropylene, Teflon, and polyamide during operation under conditions of sliding friction without lubrication. Wear behaviour of the tested specimens was investigated using ASTM G77-98 standard wear test equipment. Recording program made it possible to visualise and record the following parameters: rotational speed and load, linear wear, friction coefficient, temperature of the specimen, and ambient temperature. In addition, wear mechanisms of the analysed materials were determined with use of scanning electron microscopy. In the case of the remaining tested polymers, the most important mechanism of wear was adhesion (PP, PTFE, PA 6.6, and PA MoS2, microcutting (PTFE, PA 6.6, and PA MoS2, fatigue wear (PTFE, forming “roll-shaped particles” combined with plastic deformation (PA 6.6 and PA MoS2, and thermal wear (PP. Impregnation of polypropylene with engine oil, gear oil, or RME results in significant reduction of friction coefficient and thus of friction torque, in relation to not only unmodified polypropylene but also the examined polyamide and Teflon.

  10. Dynamic-scanning-electron-microscope study of friction and wear

    Science.gov (United States)

    Brainard, W. A.; Buckley, D. H.

    1974-01-01

    A friction and wear apparatus was built into a real time scanning electron microscope (SEM). The apparatus and SEM comprise a system which provides the capability of performing dynamic friction and wear experiments in situ. When the system is used in conjunction with dispersive X-ray analysis, a wide range of information on the wearing process can be obtained. The type of wear and variation with speed, load, and time can be investigated. The source, size, and distribution of wear particles can be determined and metallic transferal observed. Some typical results obtained with aluminum, copper, and iron specimens are given.

  11. Finger wear detection for production line battery tester

    Science.gov (United States)

    Depiante, Eduardo V.

    1997-01-01

    A method for detecting wear in a battery tester probe. The method includes providing a battery tester unit having at least one tester finger, generating a tester signal using the tester fingers and battery tester unit with the signal characteristic of the electrochemical condition of the battery and the tester finger, applying wavelet transformation to the tester signal including computing a mother wavelet to produce finger wear indicator signals, analyzing the signals to create a finger wear index, comparing the wear index for the tester finger with the index for a new tester finger and generating a tester finger signal change signal to indicate achieving a threshold wear change.

  12. An investigation of chatter and tool wear when machining titanium

    Science.gov (United States)

    Sutherland, I. A.

    1974-01-01

    The low thermal conductivity of titanium, together with the low contact area between chip and tool and the unusually high chip velocities, gives rise to high tool tip temperatures and accelerated tool wear. Machining speeds have to be considerably reduced to avoid these high temperatures with a consequential loss of productivity. Restoring this lost productivity involves increasing other machining variables, such as feed and depth-of-cut, and can lead to another machining problem commonly known as chatter. This work is to acquaint users with these problems, to examine the variables that may be encountered when machining a material like titanium, and to advise the machine tool user on how to maximize the output from the machines and tooling available to him. Recommendations are made on ways of improving tolerances, reducing machine tool instability or chatter, and improving productivity. New tool materials, tool coatings, and coolants are reviewed and their relevance examined when machining titanium.

  13. Erosion patterns produced by the paleo Haizishan ice cap, SE Tibetan Plateau

    Science.gov (United States)

    Fu, P.; Stroeven, A. P.; Harbor, J.; Hättestrand, C.; Heyman, J.; Caffee, M. W.

    2017-12-01

    Erosion is a primary driver of landscape evolution, topographic relief production, geochemical cycles, and climate change. Combining in situ 10Be and 26Al exposure age dating, geomorphological mapping, and field investigations, we examine glacial erosion patterns of the almost 4,000 km2 paleo Haizishan ice cap on the southeastern Tibetan Plateau. Our results show that ice caps on the low relief Haizishan Plateau produced a zonal pattern of landscape modification. In locations where apparent exposure ages on bedrock are consistent with the last deglaciation, complete resetting of the cosmogenic exposure age clock indicates glacial erosion of at least a few meters. However, older apparent exposure ages on bedrock in areas known to have been covered by the paleo ice cap during the Last Glacial Maximum indicate inheritance and thus limited glacial erosion. Inferred surface exposure ages from cosmogenic depth profiles through two saprolites vary from resetting and thus saprolite profile truncation to nuclide inheritance indicating limited erosion. Finally, significant nuclide inheritance in river sand samples from basins on the scoured plateau surface also indicate limited glacial erosion during the last glaciation. Hence, for the first time, our study shows clear evidence of preservation under non-erosive ice on the Tibetan Plateau. As patterns of glacial erosion intensity are largely driven by the basal thermal regime, our results confirm earlier inferences from geomorphology for a concentric basal thermal pattern for the paleo Haizishan ice cap during the LGM.

  14. Surface decontamination by cavitation erosion

    International Nuclear Information System (INIS)

    Verry, P.; Lecoffre, Y.

    1984-01-01

    The aim of the study is to show the interest of using erosion by cavitation to remove a thin layer of matter from an irradiated surface during nuclear power plant dismantling. Several cavitation devices are tested on different surfaces to erode: aluminum, stainless steel, plexiglas, paints... The process is efficient enough to measure mass loss on materials as hard as stainless steels for a pressure of only 60 bars. Qualification tests using a nozzle feed under a 300 to 600 bar pressure are envisaged

  15. Physics of soil erosion at the microscale

    Directory of Open Access Journals (Sweden)

    Philippe Pierre

    2017-01-01

    Full Text Available We focus here on the major and always topical issue of soil erosion by fluid flows, and more specifically on the determination of both a critical threshold for erosion occurrence and a kinetics that specifies the rate of eroded matter entrainment. A synthetic state-of-the-art is first proposed with a critical view on the most commonly used methods and erosion models. It is then discussed an alternative strategy, promoting the use of model materials that allow systematic parametric investigations with the purpose of first identifying more precisely the local mechanisms responsible for soil particle erosion and second ultimately quantifying both critical onsets and kinetics, possibly through existing or novel empirical erosion laws. Finally, we present and discuss several examples following this methodology, implemented either by means of experiments or numerical simulations, and coupling erosion tests in several particular hydrodynamical configurations with wisely selected mechanical tests.

  16. Wear aspects of internal combustion engine valves

    Science.gov (United States)

    Panţuru, M.; Chicet, D.; Paulin, C.; Alexandru, A.; Munteanu, C.

    2016-08-01

    Because the surface engineering is becoming an increasingly viable alternative to the constructive changes made to improve the efficiency of internal combustion engines, have been proposed and tested various types of coatings of some organs of internal combustion engines. One vital organ is the engine valves, which is subjected during operation to combined thermal, mechanical, corrosion and wear solicitations, which are leading to severe corrosion and complete breakdown. In this paper were analyzed aspects of valves wear and the active surfaces were coated using the atmospheric plasma spraying method (APS) with two commercial powders: Ni-Al and YSZ. Microstructural analyzes were made on these layers and also observations regarding the possibility of using them as thermal barrier and anti-oxidant coatings.

  17. Exposure and risks from wearing asbestos mitts

    Directory of Open Access Journals (Sweden)

    Tindall Matthew

    2005-10-01

    Full Text Available Abstract Background Very high fibre inhalation exposure has been measured while people were wearing personal protective equipment manufactured from chrysotile asbestos. However, there is little data that relates specifically to wearing asbestos gloves or mitts, particularly when used in hot environments such as those found in glass manufacturing. The aim of this study was to assess the likely personal exposure to asbestos fibres when asbestos mitts were used. Results Three types of work activity were simulated in a small test room with unused mitts and artificially aged mitts. Neither pair of mitts were treated to suppress the dust emission. The measured respirable fibre exposure levels ranged from Conclusion People who wore asbestos mitts were likely to have been exposed to relatively low levels of airborne chrysotile asbestos fibres, certainly much lower than the standards that were accepted in the 1960's and 70's. The cancer risks from this type of use are likely to be very low.

  18. Study on biocompatibility, tribological property and wear debris characterization of ultra-low-wear polyethylene as artificial joint materials.

    Science.gov (United States)

    Bian, Yan-Yan; Zhou, Lei; Zhou, Gang; Jin, Zhong-Min; Xin, Shi-Xuan; Hua, Zi-Kai; Weng, Xi-Sheng

    2018-03-10

    Ultra-low-wear polyethylene (ULWPE) is a new type polyethylene made by experts who are from China petrochemical research institute, which is easy to process and implant. Preliminary test showed it was more resistant to wear than that of Ultra-high-molecular weight polyethylene (UHMWPE). The purpose of the research is to study biocompatibility, bio-tribological properties and debris characterization of ULWPE. Cytotoxicity test, hemolysis test, acute/chronic toxicity and muscular implantation test were conducted according to national standard GB/T-16886/ISO-10993 for evaluation requirements of medical surgical implants. We obtained that this novel material had good biocompatibility and biological safety. The wear performance of ULWPE and UHMWPE was evaluated in a pin-on-disc (POD) wear tester within two million cycles and a knee wear simulator within six million cycles. We found that the ULWPE was higher abrasion resistance than the UHMWPE, the wear rate of ULWPE by POD test and knee wear simulator was 0.4 mg/10 6 cycles and (16.9 ± 1.8)mg/10 6 cycles respectively, while that of UHMWPE was 1.8 mg/10 6 cycles and (24.6 ± 2.4)mg/10 6 cycles. The morphology of wear debris is also an important factor to evaluate artificial joint materials, this study showed that the ULWPE wear debris gotten from the simulator had various different shapes, including spherical, block, tear, etc. The morphology of worn surface and wear debris analysis showed that wear mechanisms of ULWPE were adhesion wear, abrasive wear and fatigue wear and other wear forms, which were consistent with that of UHMWPE. Thus we conclude that ULWPE is expected to be a lifetime implantation of artificial joint. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. Contact Thermal Analysis and Wear Simulation of a Brake Block

    Directory of Open Access Journals (Sweden)

    Nándor Békési

    2013-01-01

    Full Text Available The present paper describes an experimental test and a coupled contact-thermal-wear analysis of a railway wheel/brake block system through the braking process. During the test, the friction, the generated heat, and the wear were evaluated. It was found that the contact between the brake block and the wheel occurs in relatively small and slowly moving hot spots, caused by the wear and the thermal effects. A coupled simulation method was developed including numerical frictional contact, transient thermal and incremental wear calculations. In the 3D simulation, the effects of the friction, the thermal expansion, the wear, and the temperature-dependent material properties were also considered. A good agreement was found between the results of the test and the calculations, both for the thermal and wear results. The proposed method is suitable for modelling the slowly oscillating wear caused by the thermal expansions in the contact area.

  20. Brake wear particle emissions: a review

    OpenAIRE

    Grigoratos, Theodoros; Martini, Giorgio

    2014-01-01

    Traffic-related sources have been recognized as a significant contributor of particulate matter particularly within major cities. Exhaust and non-exhaust traffic-related sources are estimated to contribute almost equally to traffic-related PM10 emissions. Non-exhaust particles can be generated either from non-exhaust sources such as brake, tyre, clutch and road surface wear or already exist in the form of deposited material at the roadside and become resuspended due to traffic-induced turbule...