Gwidon W. Stachowiak

Bio: Gwidon W. Stachowiak is an academic researcher from University of Western Australia. The author has contributed to research in topics: Lubrication & Lubricant. The author has an hindex of 8, co-authored 18 publications receiving 162 citations.

11 – Abrasive, Erosive and Cavitation Wear

Abstract: Publisher Summary Wear by abrasion and erosion are forms of wear caused by contact between a particle and a solid material. Cavitation is caused by the localized impact of fluid against a surface during the collapse of bubbles. Although all three forms of wear share some common features, there are also some fundamental differences, for example, a particle of liquid can cause erosion but cannot abrade. The fundamental mechanisms involved in these three forms of wear and the protective measures that can be taken against them are discussed in this chapter. The three basic forms of particle-surface interaction—abrasion, erosion, and cavitation—are shown to consist of many specific wear mechanisms. Some wear mechanisms may occur in more than one form of particle-surface interaction. Abrasive and erosive wear in particular were initially thought to consist of one or two relatively simple mechanisms but it is now realized that many processes are involved and some of them are not yet well understood. Abrasive, erosive, and cavitation wear are particularly amenable to control by careful materials selection and many wear-resistant materials have been developed for this purpose.

16 – Wear of Non-Metallic Materials

Abstract: Publisher Summary This chapter describes the fundamental wear mechanisms operating in non-metallic materials together with some prognoses concerning the future developments of these materials. Two classes of materials with entirely different characteristics—polymers and ceramics—are discussed. Polymers can provide low friction and low wear coefficients but their use is limited to lower temperatures and consequently low speeds and loads. Ceramics are resistant to high temperatures and often have a good wear resistance but their applications are limited by poor friction coefficients, especially in unlubricated applications. Ceramics and polymers are surprisingly vulnerable to accelerated wear in the presence of corrosive reagents and care should be taken in the selection of materials that are appropriate for particular operating conditions. Neither of these materials meets current or future needs, and much effort is being expended to develop new materials and improve the properties of existing materials for new and future applications. The development of polymer and ceramic matrix composites reinforced by fibers, platelets, and particulates serves as an example of these efforts. The development of new technologies, often motivated by global issues such as environmental pollution, creates new requirements for bearings and wear resistant materials that cannot be satisfied by traditional metallic materials.

2 – Physical Properties of Lubricants

Abstract: Publisher Summary The fundamental physical properties of a lubricant that determine its lubrication and performance characteristics are discussed in this chapter. There are many other parameters that describe the different physical properties of oil which can be found in the literature. In many instances, however, the specified parameters are those mentioned in this chapter. The most frequently specified parameters are those that describe the oil's lubrication characteristics and some of its main performance characteristics. In some cases there might be little variation among oils for a given parameter, or sometimes the importance of a particular parameter is not sufficiently appreciated. With the rapid development of synthetic lubricants, there will most likely be more profound differences among lubricants, and hence a greater range of specifications may be required. In simple terms, the function of a lubricant is to control friction and wear in a given system. Another important aspect is the lubricant quality, which reflects its resistance to degradation in service. Most of the present day lubricant research is dedicated to the study, prevention, and monitoring of oil degradation, since the lifetime of an oil is as important as its initial level of performance.

12 – Adhesion and Adhesive Wear

Abstract: Publisher Summary This chapter describes the process of adhesion among surfaces together with the resulting wear mechanism. A well-disguised tendency for all materials to mutually adhere when brought into a close contact is the basic cause of adhesive wear. Although atmospheric contaminants and lubricants provide effective means of preventing adhesive wear they can never entirely eliminate it. Adhesion results in high coefficients of friction and serious damage to the contacting surfaces. In extreme cases, when adhesive wear is fully established, the friction and wear rate can be so high that it may be impossible for the contacting surfaces to continue sliding. Adhesive wear is the fundamental cause of failure of most metal sliding contacts and therefore its effective prevention is essential to proper functioning of engineering machinery. Metals are particularly prone to adhesive wear hence its practical significance. Most lubricant failures in sliding metal contacts result in adhesive wear since this relates to a breakdown in the lubricant's basic function of providing some degree of separation among the sliding surfaces. If sliding surfaces are not separated, adhesion and subsequent wear are almost inevitable.

9 – Solid Lubrication and Surface Treatments

Abstract: Publisher Summary This chapter discusses the characteristic features of solid lubricants and basic surface treatments Solid lubricants and surface treatments have rapidly evolved in recent decades from simple and traditional methods to extremely sophisticated technologies These developments are part of an effort to eliminate the limitations imposed by oil-based lubrication and, in the process, are changing the general perception of the limits of wearing contacts Knowledge of the mechanisms behind these improvements in lubrication and wear resistance is, in most cases, very limited The methods employed in most studies on surface coatings are empirical and there is relatively little information available on which surface treatment is the most suitable for a particular application The economics of manufacture are already being transformed by the greater lifetimes of cutting tools, forming moulds, dies, etc The wear resistant substances may be extremely expensive in bulk, but when applied as a thin film they provide an economical and effective means of minimizing wear problems The lubricant deposition method is critical to the efficiency of the lubricating medium, since even the most powerful lubricant will be easily scraped off a wearing surface if the mode of deposition is incorrect

Electrochemical methods in tribocorrosion: a critical appraisal

Abstract: Tribocorrosion is an irreversible transformation of a material resulting from simultaneous physico-chemical and mechanical surface interactions in a tribological contact. Electrochemical methods are well suited for the study of tribocorrosion phenomena because they allow one to simulate the corrosive effect of the environment by imposing a fixed potential. Furthermore, the measurement of the anodic current permits one to determine the amount of material removed by oxidation as opposed to mechanical wear. In the present paper, experimental and theoretical aspects of applying electrochemical methods in tribology are discussed and recent results obtained with passivating metals in the authors' laboratory are presented. The importance of controlling the mechanical parameters and the contact geometry is stressed, and it is shown that these parameters can significantly affect the electrochemical response of a tribocorrosion system.