Performance surface treatments

Abstract Proper treatment of an adherend surface is one of the most important factors in assuring high initial strength and extended durability of high-performance adhesive joints. There are several requirements for a good surface preparation (1) The surface must be cleaned of any contamination or loosely bound material that would interfere with the adhesive bond. (2) The adhesive or primer must wet the adherend surface. (3) The surface preparation must enable and promote the formation of chemical and/or physical bonds across the adherend/ primer-adhesive interface. (4) The interface/interphase must be stable under the service conditions for the lifetime of the bonded structure. (5) The surface formed by the treatment must be reproducible. In this chapter, high-performance surface treatments for several metals and other materials are discussed. Surface treatments of aluminum and other metals are used to illustrate how proper surface preparations meet these requirements. 

D. Hawke and K. Gaw, "Effects of Chemical Surface Treatments on the Performance of an Automotive Paint System on Die Cast Magnesium," Paper 920074, Society of Automotive Engineers International Congress and Exposition, Detroit, Mich., 1992. 

Surface Modification. Plasma surface modification can include surface cleaning, surface activation, heat treatments, and plasma polymerization. Surface cleaning and surface activation are usually performed for enhanced joining of materials (see Metal SURFACE TREATMENTS). Plasma heat treatments are not, however, limited to high temperature equiUbrium plasmas on metals. Heat treatments of organic materials are also possible. Plasma polymerization crosses the boundaries between surface modification and materials production by producing materials often not available by any other method. In many cases these new materials can be appHed directly to a substrate, thus modifying the substrate in a novel way. 

Surface preparation, always important in obtaining optimal coatings performance, is critical for marine coatings (see Metal surface treatments). Surface preparation usually comprises about half of the total coating costs, and if inadequate may be responsible for early coating failure. Proper surface preparation includes cleaning to remove contaminants and roughening the surface to faciUtate adhesion. 

Although sol-gel treatments are still being developed, their performance is very promising. They have potential to be an environmentally compliant surface treatment for both original manufacture and repair. In some applications, they may eliminate the need for separate primers. 

When the test is to be made to predict the performance of a material in a particular service, the ideal procedure would be to have the surface of the test-pieces duplicate the surface of the material as it would be used. Here, however, a complication is presented by the fact that materials in service are commonly used in several forms with different conditions of surface. Where the number of materials to be compared is large, it will usually be impractical to test all the conditions of surface treatment of possible interest. The best practical procedure, then, is to choose some condition of surface more or less arbitrarily selected to allow the materials to perform near the upper limits of their ability. If all the materials to be tested are treated in this way, and preferably with uniform surface treatment, the results of the test will indicate the relative abilities of the different materials to resist the test environment when in a satisfactory condition of surface treatment. Then, if it should be considered prudent or desirable to do so, the most promising materials can be subjected to further tests in a variety of surface conditions so that any surface sensitivity can be detected. 

Glass fibers and most other reinforcements require special surface treatment to ensure the bonding and compatibility of the fibers to the plastic in order to maximize performances. Treatments are also used to protect individual filaments during handling and processing (7,14). 

The CRC-Elsevier materials selector , 2nd edition, N.A. Waterman, and M.E Ashby CRC Press (1996) ISBN 0412615509. (Now, also available on CD-ROM). Basic reference work. Three-volume compilation of data for all materials includes selection and design guide. The Materials Selector is the most comprehensive and up-to-date comparative information system on engineering materials and related methods of component manufacture. It contains information on the properties, performance and processability of metals, plastics, ceramics, composites, surface treatments and the characteristics and comparative economics of the manufacturing routes which convert these materials into engineering components and products. 

A study on surface treatment of Nation membrane and its effects on cell performance... 

Films of polyolefins, polyamides and poly(vinylidene dichloride) are made using this technique. As most of the films are used for flexible packaging, further down-stream surface treatments are usually applied to improve performance. For example, aqueous polymer emulsions, e.g., poly(vinylidene dichloride), or delaminated clay particles improve the barrier properties as will metallising with aluminium vapour. Corona discharge, causing slight surface oxidation, improves printability. 

TEG macrostructure differs from that of natural graphite it possesses abnormally high porosity and highly developed active surface (40-50 m2/g) (Figure 1). The performed thermochemical treatment leads to an essential exfoliation of graphite matrix with a formation of cellular structure. The thickness of cell s walls is equal to 20-25 nm. The surface of cell s walls contains a lot of macrocracks, outcrops of crystallites, etc. The thermochemical re-treatment was applied to enhance TEG dispersivity. 

Menzies, D. B. Dai, Q. Bourgeois, L. Caruso, R. A. Cheng, Y. B. Simon, G. P. Spiccia, L. 2007. Modification of mesoporous Ti02 electrodes by surface treatment with titanium(IV), indium(III) and zirconium(IV) oxide precursors Preparation, characterization and photovoltaic performance in dye-sensitized nanocrystalline solar cells. Nanotechnology 18 125608. 

ANODE MODIFICATION FOR ENHANCING OLED PERFORMANCE 6.2.1 Indium Tin Oxide Surface Treatment and Modification... 

Surface Treatments 13. Use zinc coating primer (Ensure clean surface for metal joining) 14. Spray on a silicone coating 21. Treat the surface with alkali (Alkali may affect the product s performance) 34. Try a polymer with a protective layer and heat to use (Troublesome as heating of the polymer is required) 56. Blow dry the surface (Not user friendly and time consuming)... 

Control of fiber friction is essential to the processing of fibers, and it is sometimes desirable to modify fiber surfaces for particular end-uses. Most fiber friction modifications are accomplished by coating the fibers with lubricants or finishes. In most cases, these are temporary treatments that are removed in final processing steps before sale of the finished good. In some cases, a more permanent treatment is desired, and chemical reactions are performed to attach different species to the fiber surface, e.g. siliconized slick finishes or rubber adhesion promoters. Polyester s lack of chemical bonding sites can be modified by surface treatments that generate free radicals, such as with corrosive chemicals (e.g. acrylic acid) or by ionic bombardment with plasma treatments. The broken molecular bonds produce more polar sites, thus providing increased surface wettability and reactivity. 

The process can be used to immobilize heavy metals such as Cd, Zn, Cu, Pb, Ni and Co. Cr(VI) can be reduced by some metal-reducing bacteria to the less toxic and less soluble form Cr(III). Arsenate [As(V)] can be reduced to the more mobile arsenite [As(III)] which precipitates as AS2S3, and is insoluble at low pH. Several laboratory-scale tests (batch and column) are currently available to study the feasibility of this process. However, only a few field tests have been performed to date. Two such tests have been conducted in Belgium, one at a non-ferrous industrial site, where the groundwater was contaminated with Cd, Zn, Ni and Co, and the other which was treated by injection of molasses in order to reduce chromium (VI) to chromium (III). A third demonstration in The Netherlands has been performed at a metal surface treatment site contaminated by Zn. The outcomes of a batch test of a groundwater heavily contaminated by Zn, Cd, Co and Ni are presented in Table 5. The initial sulphate concentration was 506mg/l. With the addition of acetate, a nearly... 

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