Aggressive wear applications

For aggressive wear applications, a wear-resistant deposit can be welded or flame applied to the flight face. One technique analogous to wear boxes on chutes is to lay spaced radial runs of hard weld deposit, to capture fines in the spaced pockets. A thin bed of the material being handled then presents a layer of like material as a working face. However, the surface slip behaviour on the screw face is then a factor of the internal friction of the material, rather than of a smooth metallic interface. 

Most screening machines are designed and fabricated such that their useful service lives are measured in decades rather than years in most applications. However, some applications can dramatically shorten service Ufe. Abrasive materials can cause premature wear, particularly when process rates are high. Some materials attack the screener s metal components. Salts, such as sodium chloride, calcium chloride, and ammonium sulfate, are particularly aggressive. In such cases, selection of the materials of construction is critical to maximizing screener service life. In this matter, it is best to work closely with the manufacturer, sharing all pertinent process parameters so recommendations can be made based on their experience with similar systems. 

Polyamide-6 (Nylon-6, Perlon) and polyamide-6.6 (Nylon-6.6) are the most well known polyamides. Polyamide-based filaments find wide spread applications as yarns for textile or industrial and carpet materials [70], However, nylon-based textiles are uncomfortable to wear and difficult to finish due to their hydrophobic character. This characteristic also leads to fouling of PA-based ultrafiltration membranes by proteins and other biomolecules which increases the energy demand for filtration and requires cleaning with aggressive chemicals or replacement [71-73], Consequently the enhancement of the hydrophilicity of nylon is a key requirement for many applications and can be achieved by using plasma treatment [74-76], As a promising alternative, enzymatic hydrophilization of PA requires less energy and is not restricted to planar surfaces. 

The application of selected protective coatings enables iron and steel components to be used in many otherwise prohibitively aggressive enviromnents. In this way, the obvious advantages of cheap unalloyed ferrous metals (e.g., good mechanical properties, ease of fabrication, etc.) may be economically combined with the increased resistance to corrosion, heat, and/or wear endowed by such surface treatments. 

Bioceramic Applications The performance requirements of yttria-stabilized tetragonal zirconia polycrystal (TZP) to form biocompatible, strong components for use as hip, knee, and dental prostheses, and which demonstrate long-term resistance against aggressive body fluids and mechanical wear and tear, during a predicted lifetime of 15-20 years in the human body, include ... 

Ceramic Structural Materials Replacing Metals An important category of advanced ceramic materials comprise stmctural materials, developed, still in the spirit of the Industrial Revolution, to replace metals in all applications where higher rigidity, hardness and resistance to wear and an aggressive environment is required... 

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