Abrasion Resistance

Abrasion Resistance is the ability of a material to withstand mechanical action such as rubbing, scraping, or erosion, that tends progressively to remove material from its surface. Such ability helps to maintain the material's original appearance and structure. Abrasive wear occurs when a hard rough surface slides across a softer surface. ASTM (American Society for Testing and Materials) defines it as the loss of material due to hard particles or hard protuberances that are forced against and move along a solid surface. Abrasive wear is commonly classified according to the type of contact and the contact environment.  The type of contact determines the mode of abrasive wear. The two modes of abrasive wear are known as two-body and three-body abrasive wear. Two-body wear occurs when the grits, or hard particles, are rigidly mounted or adhere to a surface when they remove the material from the surface. The common analogy is that of material being removed with sand paper. Three-body wear occurs when the particles are not constrained and are free to roll and slide down a surface. The contact environment determines whether the wear is classified as open or closed. An open contact environment occurs when the surfaces are sufficiently displaced to be independent of one another. There are a number of factors which influence abrasive wear and hence the manner of material removal. Several different mechanisms have been proposed to describe the manner in which the material is removed. Three commonly identified mechanisms of abrasive wear are: Plowing, Cutting and Fragmentation. Plowing occurs when material is displaced to the side, away from the wear particles, resulting in the formation of grooves that do not involve direct material removal. The displaced material forms ridges adjacent to grooves, which may be removed by subsequent passage of abrasive particles. Cutting occurs when material is separated from the surface in the form of primary debris, or microchips, with little or no material displaced to the sides of the grooves. This mechanism closely resembles conventional machining. Fragmentation occurs when material is separated from a surface by a cutting process and the indenting abrasive causes localized fracture of the wear material. These cracks then freely propagate locally around the wear groove resulting in additional material removal by spalling. Abrasive wear can be measured as loss of mass by the Taber Abrasion Test according to ISO 9352 or ASTM D 1044.

PTFE/PFA BLENDS
Are superior non-stick finishes from Dupont and Whitford Worldwide. These coatings are three-coat (primer/mid-coat/top-coat) systems formulated with PTFE and PFA. Characteristics of these blended coatings are similar to other PTFE coatings, however durability is greatly increased by a ceramic reinforcing component which gives it higher scratch and abrasion resistance with a maximum continuous use temperature of (290° C [500°F]) and an intermittent temperatures as high as (315°C [600°F]).

Praxair/Tafa Arc Spray Cobalt Alloy-106 MXC®

Made exclusively for arc spraying, Praxair/TAFA 106 MXC is used to produce a Rc 48 wear resistant coating that resists particle erosion at temperatures from 1000 - 1550°F (540-840°C), and is suitable for exhaust valves and seats. Mis-machined or worn parts may be rebuilt with 106 MXC and re-machined using various grinding techniques. Turbine air seals and turbine vanes coated with 106 MXC withstand fretting in high temperature environments. Several major manufacturers of aircraft engines are evaluating Praxair/Tafa 106 MXC as a cost-effective alternative to plasma sprayed material that conforms to PWA 53-16 and PWA 53-18