Showing papers on "Tribocorrosion published in 2008"

Materials and Surface Engineering in Tribology

Abstract: Foreword. Preface. Chapter 1. Surfaces. 1.1 Introduction. 1.2 The surface state. Chapter 2. Tribology. 2.1 Introduction. 2.2 Elements of solid mechanics. 2.3 Elements of contact mechanics. 2.4 Friction. 2.5 Nanotribology. 2.6 Wear. 2.7 Lubrication. 2.8 Wear-corrosion: tribocorrosion and erosion-corrosion. Chapter 3. Materials for Tribology. 3.1 Introduction. 3.2 Bulk materials. 3.3 Surface treatments and coatings. 3.4 Hard anti-wear and decorative coatings. 3.5 Characterization of coatings: hardness, adherence and internal stresses. Bibliography. Index.

The Effects of proteins and pH on tribo-corrosion performance of cast CoCrMo – a combined electrochemical and tribological study

Abstract: In this study, the wear-corrosion of cast CoCrMo, more specifically, sliding wear-corrosion and abrasive wearcorrosion (using ∼ 4 μm SiC abrasive particles) have been investigated using a modified ball-cratering rig with a threeelectrode electrochemical cell. The concentration effects of proteinaceous material (25% and 50% bovine serum) and pH levels, i.e., pH 4.0 (the possible pH for an infected joint area) and pH 7.4 (the normal pH for a healthy joint) on the tribocorrosion performance of the alloy are explored. Results show that protein adsorption was dependent on pH and protein concentration. The protein adsorption in turn influenced the overall tribo-corrosion performance of the CoCrMo alloy, including the in situ electrochemical noise, the specific wear rates, as well as the wear scar morphologies. The proteins and the pH level of hip joint environments play a significant role in the tribo-corrosion performance of the cast CoCrMo and a discussion of the combined wear and corrosion mechanisms will be presented.

Definition and Importance of Corrosion

Abstract: Corrosion is the destructive attack of a metal by chemical or electrochemical reaction with its environment. Deterioration by physical causes is not called corrosion, but is described as erosion, galling, or wear. In some instances, chemical attack accompanies physical deterioration, as described by the following terms: corrosion – erosion, corrosive wear, or fretting corrosion. Nonmetals are not included in this defi nition of corrosion. Plastics may swell or crack, wood may split or decay, granite may erode, and Portland cement may leach away, but the term corrosion, in this book, is restricted to chemical attack of metals. “ Rusting ” applies to the corrosion of iron or iron base alloys with formation of corrosion products consisting largely of hydrous ferric oxides. Nonferrous metals, therefore, corrode, but do not rust.

Ionic Liquids Interactions with Materials Surfaces Applications in Tribology and Nanotechnology

Abstract: The extraordinary combination of high thermal stability, low volatility and the possibility of tailoring the physical and chemical properties of ionic liquids (ILs) by modifying their molecular features such as the length and nature of the cation lateral chains and the anion size and composition, has open the field of application of these green ordered fluids. ILs have shown their ability to provide effective lubrication with very low friction coefficients and wear rates under conditions for which the currently used lubricating fluids fail. These conditions cover strategic technologies such as aerospace, microelectronics and nanotechnology applications. At the present moment, there exist no liquid lubricants for high temperature, high vacuum and cryogenic conditions. We have determined the lubricating ability of ILs under extreme temperature conditions. We have determined the conditions for the formation of tribocorrosion reaction products at metal-metal and metal-polymer interfaces. In the case of fluorine or phosphorus-containing imidazolium ionic liquids, formation of metallic fluorides and phosphates at the contact surfaces is the determining wear mechanism step. The surface interactions of imidazolium room temperature ILs have been studied in a variety of materials in sliding contact under variable conditions, both as neat lubricants and as additives of conventional basestocks. The ability of ILs molecules to interact with surfaces has also been explored in nanotechnology applications. It is well known that the use of ILs as solvents in the synthetic route, allows the control of size and shape of a variety of nanoparticles. We have developed new polymer/IL/nanoparticle nanocomposites where the size, morphology and distribution of the nanoparticles are controlled by surface interactions with IL molecules.

The Influence of Fretting Parameters on Tribocorrosion Behaviour of AISI 304L Stainless Steel in Ringer Solution

Abstract: Medical applications where tribocorrosion has to be considered are orthopaedic and prosthetic implants, hip joints, amalgam restorative materials, and orthodontic brackets-archwire structures. In most cases, the degradation of biocompatible implant materials can lead to failure of medical therapy and cause a tissue inflammation. The dependence of the tribocorrosion of stainless steels AISI 304L orthodontic archwires sliding against corundum in Ringer’s solution on applied normal force, and sliding velocity, has been investigated using in-situ electrochemical current-potential measurements. Applied normal force and sliding velocity were found to greatly affect current and potential during fretting-corrosion. An increase in normal force and sliding velocity induce an increase in current and a decrease in potential accelerating the depassivation rate of the tested stainless steels. Sliding wear affects the repassivation behaviour of stainless steel by increasing the anodic current in the wear track area.