Abrasion treatment metals

Abrasive treatments consist of scouring, machining, hand sanding, and dry and wet abrasive blasting. The abrasive medium can be fine sandpaper, carborundum or alumina abrasives, metal wools, or abrasive shot. Mechanical abrasion is usually preceded and followed by solvent cleaning. The choice is generally determined by available production facilities and cost. 

The mechanical processes, as shown previously for other metals, employ mechanical abrasion or impact (shotblasting) forces to clean the surface. Both poor joint strength and durability result from mechanical abrasion treatment. With alumina blasting the results are good joint strength but only adequate durability. 

Barrels and screw are normally nitrided steel for long life. Through hardened barrels are available and some barrels are lined with wear resistant liners to increase life. Liners provide resistance to corrosion and abrasion. Other metal treatments are available to increase service life. 

Fluorotitanic acid is used as a metal surface cleaning agent, as a catalyst, and as an aluminum finishing solvent (see Metal surface treatments). Fluorotitanates are used in abrasive grinding wheels and for incorporating titanium into aluminum aHoys (see Abrasives Aluminumand aluminum alloys). 

Although abrasive polishing is the most common metal polishing operation, other forms of polishing and chemical brightening are used ia iadustrial operations. Aluminum tmck trailers often are cleaned and brightened by treatments with strong acids or alkaHes, which chemically remove oxides. Chemical methods can also remove tarnish from other metals (55,56). 

Plasma processing technologies ate used for surface treatments and coatings for plastics, elastomers, glasses, metals, ceramics, etc. Such treatments provide better wear characteristics, thermal stability, color, controlled electrical properties, lubricity, abrasion resistance, barrier properties, adhesion promotion, wettability, blood compatibility, and controlled light transmissivity. 

More uniform results may be expected if a substantial layer of metal is removed from the specimens to ehminate variations in condition of the original metaUic surface. This can be done by chemical treatment (pickling), electrolytic removal, or grinding with a coarse abrasive paper or cloth, such as No. 50, using care not to work-harden the surface. At least 2.5 X 10 mm (0.0001 in) or 1.5 to 2.3 mg/cm (10 to 15 mg/iu") should be removed. If clad alloy specimens are to be used, specif attention must be given to ensure that excessive metal is not removed. After final preparation of the specimen surface, the speci-... 

In 2007 a new line of organofunctional and alkylsilane water-based sol gel products called Dynasylan Hydrosil (trademarks of Evonik) entered the market.19 They provide good corrosion and abrasion protection for valuable metal surfaces. They also provide coatings of excellent adhesion, without the need to use chromium(vi), a carcinogenic metal ion still widespread in corrosion treatment formulations. 

Before a product coating can be applied to a surface, the surface must be free from contamination. As described elsewhere in this report, many different types of abrasives, alkalines, acids, and solvents, as well as water, are used by industry to clean metal surfaces. Once a part is cleaned, surface treatment such as phosphate coating can be applied if desired. The purpose of surface treatment is to condition or prepare the surface so that the paint forms a better bond with the metal surface. 

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