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Wear Process (wear + process)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Fretting fatigue strength of SCM435H steel and SUH660 heat-resistant steel in hydrogen gas environment

LUBRICATION SCIENCE, Issue 3 2008
M. Kubota
Abstract Utilisation of hydrogen is expected to be one of the solutions against the problems of exhaustion of fossil fuels and reduction of carbon dioxide emissions. Evaluation of the materials for hydrogen utilisation machines is required. The objectives of this study are the characterisation of fretting fatigue strength of low-alloy steel SCM435H and heat-resistant steel SUH660, and the validation of effectiveness of nitriding in hydrogen gas environment. Fretting fatigue tests were conducted up to 3 × 107 cycles. The decrease of fretting fatigue strength in hydrogen gas environment was found at the long-life region exceeding 107 cycles. The amount of the decrease of the fretting fatigue limit at 3 × 107 cycles was 11% for SCM435H and 15% for SUH660. However, at the stress level above the fretting fatigue limit in air, the finite life in hydrogen gas increased more than that in air. The cause of extension of fatigue life was the delay of start of stable crack propagation. Fretting fatigue crack, which was smaller than 200,µm in length, consumed approximately 60% of the fatigue life in hydrogen gas environment. Fretting fatigue crack was steadily propagated after the test was started in air. Observations of the fretted surface showed that the fretting wear process in hydrogen gas environment was dominated by adhesion. Tangential force coefficient was higher in hydrogen gas environment than that in air. It is considered that the adhesion has a close relation to crack initiation in hydrogen gas environment, and as a result, the failure of specimen occurred at a lower stress level comparing the fretting fatigue limit in air. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Combined Wear Behavior and Long-Term Implant-Bone Fixation of Total Knee Replacement: A Novel In Vitro Set-up

ARTIFICIAL ORGANS, Issue 5 2010
Michele Spinelli
Abstract The success of a total knee replacement (TKR) strongly depends on the prosthetic design; this includes on one hand the best choice of the bearing materials to minimize wear, on the other hand a good orientation of the prosthetic components with respect to the loading directions. The aim of this study was to investigate the feasibility of a new experimental setup combining two fundamental aspects for the long-term success of knee implants: wear and micromotions. A novel procedure was used to simulate working conditions as close as possible to in vivo ones and to measure implant-bone micromotion, by means of fixing the femoral component of the prosthesis to the distal part of a synthetic femur to be tested through a knee simulator. Gravimetric wear of the tibial specimens was assessed at regular intervals. Implant-bone inducible micromotions and permanent migrations were measured at three locations throughout the test. Wear patterns on tibial specimens were characterized through a standardized protocol based on digital image analysis; fatigue damage in the cement was quantified. Some initial conditioning was noticed both in the wear process and microcracking distribution within the cement mantle. Similarity in wear tracks observed on tibial inserts and other retrieval studies, coupled with clinically consistent migration patterns for TKR, supports the efficacy of the new in vitro method presented. [source]

Commissurotomy for improving access to the oral cavity of the wombat

AUSTRALIAN VETERINARY JOURNAL, Issue 7 2010
GJ Wilson
Wombats are a grazing marsupial with a diet rich in silicates, which is highly abrasive and results in a higher rate of tooth attrition than in other grazing marsupials such as kangaroos. Any interference in the natural wear process, such as malocclusion or loss of teeth, causes overgrowth of teeth. The small mouth opening of the wombat makes access to the caudal mouth difficult and overgrowth of cheek teeth can be difficult to treat effectively. This case report describes a technique that greatly improves access to allow dental treatment of all overgrown teeth with minimal complications. [source]

Tribological Studies of a Zr-Based Glass-Forming Alloy with Different States,

ADVANCED ENGINEERING MATERIALS, Issue 11 2009
Feng Jiang
Abstract The tribological characteristics of a glass-forming alloy, Zr52.5Cu17.9Ni14.6Al10.0Ti5.0, in atomic percent (at.%, Vit 105), with different microstructural states have been investigated. Friction and wear studies were conducted using a ball-on-flat reciprocating sliding apparatus against an AISI E52100 bearing steel under dry condition. The observed wear resistance in an ascending order is: the deformed, creep-tested, and as-cast states. Wear analyses suggested that the wear processes of glass-forming alloys involved abrasion, adhesion, and oxidation. The differences in hardness, free volume, and brittleness in different states significantly affected the friction and wear behaviors of the glass-forming alloys. [source]