Metals pretreatment

D. B. Freeman, Phosphating and Metal Pretreatment, Woodhead Faulkner, Cambridge, U.K., 1986. 

Eor the cover-coat direct-on process, a ferric sulfate [10028-22-5] Ee2(S0 2> etch is included in the metal pretreatment for rapid metal removal. It is designed to remove ca 20 g/m (2 g/ft ) of iron from the sheet metal surface. Hydrogen peroxide [7722-84-1/, H2O2, is added intermittently to a 1% ferric sulfate solution to reoxidize ferrous sulfate [7720-78-7] EeSO, to ferric sulfate. 

Care must be taken here not to confuse acid cleaners with the high-strength, phosphoric acid-based chemical polishes and chemical brighteners, which are used specifically to obtain the surface finish which such materials produce. Also in the category of acid cleaners could be considered the lightweight alkali-metal phosphating cleaner-coater solutions, but a discussion on such materials is best left to specialist publications on metal pretreatment chemicals. 

The metal pretreatment process requires ceneful selection, particularly with the cathodic process. BS4479 1990, Part 3, Recommendations for Conversion Coatings should be consulted. 

Cooke, B. A., Aspects of Metal Pretreatment before Painting , Proc. IX Int. Conf. Org. Sci. and Tech., Athens, 29-46 (1983)... 

After metal pretreatment it is essential that a suitably formulated adhesive primer is used, because p.v.c. does not itself adhere to metals. 

A recent stndy (13,27) describes the use of Co-Si-TUD-1 for the liquid-phase oxidation of cyclohexane. Several other metals were tested as well. TBHP (tert-butyl hydroperoxide) was used as an oxidant and the reactions were carried out at 70°C. Oxidation of cyclohexane was carried out using 20 ml of a mixture of cyclohexane, 35mol% TBHP and 1 g of chlorobenzene as internal standard, in combination with the catalyst (0.1 mmol of active metal pretreated overnight at 180°C). Identification of the products was carried out using GC-MS. The concentration of carboxylic side products was determined by GC analysis from separate samples after conversion into the respective methyl esters. Evolution and consumption of molecular oxygen was monitored volumetrically with an attached gas burette. All mass balances were 92% or better. 

Organic compounds, sulphur-, phosphorous- and nitrogen-compounds may be present as soluble, suspended or colloidal particles. This also holds for salts, bases and heavy metals. Pretreatment can change the physical state of pollutants in the wastewater. This gives a possibility for guiding the treatment process. 

There are numerous metal pretreatment techniques that can be used in addition to solvent degreasing. To obtain metal/polymer systems which exhibit strong initial adhesion it is usually sufficient to wash the metal with a solvent followed by an acid etch or sandblasting technique to remove any weak oxide layers and roughen the surface simultaneously. 

Figure 3 241 illustrates that the durability of metal/polymer adhesion systems can greatly be influenced by the metal pretreatment chosen 1 K Therefore, it is very important to select the best pretreatment for a given system. 

A summary of some of the more common metal pretreatments is given by Derjaguin25). The literature also describes many specialized pretreatments for steel 26-29>, stainless steel 22,30), aluminum 23,31 35 copper 36 41) and other metals... 

In this series of papers we will report on the use of TOFSIMS for the characterization of films of a number of commonly used silanes deposited on various substrates, mainly metals. The background of this interest in metals is the possible application of silanes as corrosion-inhibiting metal pretreatments. 

Application of models, such as clean surfaces of single crystals of metals pretreated under carefully controlled conditions, undoubtedly brings us nearer to knowledge about the situation on a metal surface on an atomic scale. On the other hand, the currently insufficient state of development of sophisticated techniques (theory and experiment) rather rarely allows us... 

Protective Coating, Integral Fuel Tank Coating, Polyurethane, Rain, Erosion Resistant Resin-Acid Metal Pretreatment Compound for Aircraft Cement Rubber... 

Lead chromate pigments are mainly used as corrosion inhibitive pigments. These pigments are of low opacity and can be combined with higher opacity pigments for use in primers. Zinc chromate, also an anti-corrosion pigment, is used in metal pretreatments such as wash primer, which also promotes adhesion to aluminum and steel. 

Analysis of the Non Metallized. Pretreated Polypropylene. In a previous paper (1), we have shown that for very short treatment times (23 ms) in N2 or NH3 plasma, the first observed effect of the plasma was an increase of the dispersive component (y ) of the polypropylene surface tension. Since almost no nitrogen nor oxygen were detected by XPS for treatment times shorter than 0.7 s, it was concluded that the plasma had first a physical effect rather than a chemical one, although the efficiency of the treatment on the Al-PP adhesion was high (as proven by the use of a scotch-tape test). 

Presently available reports on catalysis over glassy metals are listed in Table 4.1. In most catalytic applications of glassy metals, pretreatment of the as-quenched materials (e.g., in a reducing gas atmosphere) was found to be crucial to obtain high catalytic activities. Several factors may contribute to this behavior, the most important being (i) the surfaces of metallic alloys exposed to air are likely to be covered with a superficial layer of inactive metal oxides (ii) the surface area of as-quenched materials is very small (usually less than 0.1 m2/g) and is therefore easily deactivated in the presence of contaminants. 

High-solid vinyl latexes can "skin over" in a dip tank if agitation is not provided. (Note many metal pretreatments make metal surfaces hydrophobic, i.e., it will not be wet out readily by a water-based system). 

For the cover-coat direct-on process, a ferric sulfate [10028-22-5], Fe2(S0 2 is included in the metal pretreatment for rapid metal removal. It is... 

EIS and other electrochemical methods appear to be useful for the study of the performance of metal pretreatments (cleaning processes, anodization, phosphating, chro-mating, etc.) prior to adhesive bonding. A quick comparison of methods can be achieved, and because the method is fast and straightforward, it can be used as a quality control method. On adhesively bonded system EIS could be performed in more fundamental studies that would provide information on the nature and locus of degradation processes, when immersed in aggressive solutions. 

I. Freeman, D. B. Phosphating and Metal Pretreatment Industrial Press, Inc. New York, 1986. 

Uses Binder insolubilizer tor paper and board coatings, nonwoven tab-rics deposit controi agent in wet-end paper processes str. additive tor alkaiine-sized paper component of waterborne inks, overprint varnishes, adhesives textiie, ieather, and paper water-repeiient formuiations antimicrobial treatment for textiles and timber coaguiant in mfg. of syn. leather cloth metal pretreatment coatings precursor to zirconia in cata-lyst systsms... 

CAS 3794-83-0 EINECS/ELINCS 223-267-7 Uses Sequestrant, corrosion inhibitor, scale inhibitor, pigment dispersant for industrial cooling and boiler water treatment, metal pretreatment for coatings, drilling muds and kaolin clay slurries, metal finishing protects against rancidification in cosmetics, personal care prods. stabilizer for peroxide bleaching sol ns. in textiles, paper pulp Properties Wh. crystalline powd. 4.0% max. on 16 mesh 10% max. thru 325 mesh 100 min. mean particle size m.w. 294 bulk dens. 0.65-0.95 g/cc pH 11-12 (1%) 57-62% total act. acid 7-11% moisture D.E.R. 317 [Dow/Epoxy Prods. Intermeds.j... 

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