Adhesive wear fretting

Oxidation is the most common factor in the fretting process. In oxidizing systems, fine metal particles removed by adhesive wear are oxidized and trapped between the fretting surfaces. The oxides act like an abrasive (such as lapping red) and increase the rate of... 

For systems consisting of common materials (e.g., metals, polymers, ceramics), there are at least four main mechanisms by which wear and surface damage can occur between solids in relative motion (1) abrasive wear, (2) adhesive wear, (3) fatigue wear, and (4) chemical or corrosive wear. A fifth, fretting wear and fretting corrosion, combines elements of more than one mechanism. For complex biological materials such as articular cartilage, most likely other mechanisms are involved. 

The mechanical contribution to fretting damage may include elements of adhesive wear, microscopic fatigue crack development and delamination that result in removal of small particles from the metal lattiee. The particles form a debris, which may partly adhere to the fretting surfaces and be trapped between these, and may partly escape from the fretting area. 

Sn 8-12 Soft and ductile low melting Overlay coatings for pistons point resistant to fretting, in internal combustion scuffing and adhesive wear engines corrosion protection ... 

Fretting or adhesive wear is caused by the formation of a local interfacial adhesion connection and subsequent tearing off of solid bonds, combined with material outbreak and transmission (DIN 50323-2). The surfaces of the friction partners form a tight, adhesive bond in poor lubrication and contact conditions or dry-run. 

A specific form of wear is that of tool life, where a coated tool surface is used to machine a metal and the tool velocity, pressure, and contact distance (revolutions) are used as variables, Fretting (adhesive) wear is encountered where materials slide against one another and adhesion between the surface is important to the wear mechanism. This type of wear is encountered in electrical coimectors and affects contact resistance. Fretting is of particular concern at high temperatures and when metals lose their natural oxide layers. Wear and surface composition may be studied in situ in the SEM by the use of appropriate fixturing.t These wear studies can also contribute to contact resistance studies, particularly when light contact loads are used. 

Fretting at very low temperatures (4K) has been investigated. The situation appears to be similar to that in high vacuum. An oxide film does not grow at this temperature and so coefficients of friction are high due to adhesion but little wear occurs . 

Mechanism. Basically, fretting is a form of adhesive or abrasive wear, where the normal load causes adhesion between asperities and oscillatory movement causes ruptures, resulting in wear debris. Most commonly, fretting is combined with corrosion, in which case the wear mode is known as fretting corrosion. For example, in the case of steel particles, the freshly worn nascent surfaces oxidize (corrode) to FejO, and the... 

There are other mechanisms such as fretting, fretting corrosion, and fretting CF, which is a combination of adhesive, corrosive, and abrasive forms of wear. Wear by all mechanisms except fatigue mechanism, occurs by gradual removal of material. One or more of these mechanisms may be operating in a particular machine. In many cases, wear may be initiated by one mechanism but may proceed by other mechanisms and thereby complicate failure analysis (60). 

Again, wear is the removal of material. The idea that friction causes wear and therefore, low friction means low wear, is a common mistake. Brief descriptions of five types of wear abrasive, adhesive, fatigue, chemical or corrosive, and fretting — may be found in Reference 2 as well as in other references in this article. Next, it maybe useful to consider some of the major concepts of lubrication. 

Wear is defined as the damage to a solid surface, generally involving progressive loss of material, due to relative motion between that surface and a contacting substance or substances. The mechanisms of wear are abrasion, adhesion, erosion, fatigue and fretting. 

For example, hydroxyapatite (HA), a typical CaP, is an osteoconductive material that has been shown to promote osteoblast adhesion, and which has been widely used as a coating for orthopaedic and dental implants. However, the loss of ELA coating owing to delamination leads to micromotion of the implant and increased fretting and wear debris particles, which may cause failure of the implant. Therefore, it has been proposed to combine HA (a relatively insoluble calcium ceramic) and tricalcium... 

Fretting wear (contamination control) A type of wear where adhesion between two... 

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