Chromating replacements for

Huang Xingqiao, Ning Li, Huiyong Wang, Hanxiao Sxm, Shanshan Sun, Jian Zheng, (2008).Electrodeposited cerium film as chromate replacement for tin plate. Thin Solid Films, Vol.516, No. 6, (January 2008) pp. 1037-1043, ISSN 0040 - 6090... 

T. Peng and R. Man, Rare earth and silane as chromate replacers for corrosion protection on galvanized steel , J. Rare Earths 27,159 (2009). 

Ferreira, M.G.S., Duarte, R.G., Montemor, M.F., and Simoes, A.M.P., Silanes and rare earth salts as chromate replacers for pre-treatments on galvanised steel. Electrochimica Acta, 2004. 49(17-18) 2927-2935. 

Palanivel V., Zhu D. and van Ooij W. J. (2003), Nanoparticle-fllled silane films as chromate replacements for aluminum alloys . Prog. Org. Coat, 47, 384-92. 

Given some basic information about the corrosion inhibition mechanisms of chromates, many studies have been conducted for chromate replacements. For effective replacement of hexavalent Cr, however, an inhibitor has to inhibit the oxygen reduction reaction as well as anodic dissolution/pitting, and several studies indicate that hybrid formulations seem to be the best way to do just that. Typically, in these hybrid formulations an organic oxygen reduction reaction inhibitor is included with environmentally benign anodic inhibiting anions. 

The need to identify replacements for chromate-based technologies has also resulted in the development of alternatives to resin-based corrosion-inhibiting primers. These are primarily inorganic barrier coating techniques, such as sol-gel processes, which may or may not include corrosion inhibitors. These are discussed in a later section. 

Adsorption inhibitors act by forming a film on the metal surface. The action of traditional oil-based red lead paint formulations presumably involves the formation of soaps and the precipitation of complex ferric salts that reinforce the oxide film. There has been substantial interest in recent years in development of replacements for lead-based and chromate-based inhibitor systems. Adsorption inhibitors based on pol3rmers have been of particular interest. In this volume, Johnson et al. and Eng and Ishida discuss inhibitors for copper 2-undecylimidazole is shown to be effective in acid media, where it suppresses the oxygen reduction reaction almost completely. Polyvlnyllmidazoles are shown to be effective oxidation inhibitors for copper at elevated temperatures. Also in this volume, Chen discusses the use of N-(hydroxyalkyl)acrylamide copolymers in conjunction with phosphate-orthophosphate inhibitor systems for cooling systems. 

A less expensive replacement for zinc chromate is obtained by combining the zinc salt of 5-nitroisophthalic acid with zinc phosphate pigments (Section 5.2.2.5) [5.65], [5.67], [5.181]. A concentration of 0.5-2.0% based on the liquid coating is recommended. 

M. W. Kendig, S. Jeanjaquet, M. Cuinningham. Replacement for Chromate Conversion Coating and Anodization. 1993. 

A number of compounds contain the K+ ion, and in many cases have the same uses as the corresponding sodium compounds. Examples in which K+ is found include potassium chloride, bromide, iodide, cyanate, nitrate, sulfate, acetate, carbonate, chlorate, chromate, dichromate, ferricyanide, cyanide, hydroxide, perchlorate, permanganate, and persulfate. In household and kitchen products, potassium chloride (KCl) substitutes for NaCl for people with sensitivity to the Na+ in ordinary table salt. As a replacement for sodium chloride, potassium chloride may be recommended to reduce high blood pressure... 

The 2002 US Presidential Green Chemistry Challenge Awards (see Box 8.3) recognized the development of a copper-based environmentally advanced wood preservative as a replacement for chromated copper arsenate. The new preservative contains a copper(II) complex and a quaternary ammonium salt. Its introduction into the market coincides with a change of policy within the wood-preserving industry arsenic-based products should have been eliminated by the end of 2003. 

Chem. Descrip. Zinc phosphate dihydrate CAS 7779-90-0 EINECS/ELINCS 231-143-9 Uses Corrosion inhibitor, pigment for coatings Features Replacement for zinc chromate, lead oxide, strontium chromate, barium chromate, etc. 

Features Highly effective heavy metal-free replacement for toxic anticorrosive pigments such as red lead, zinc chromate, strontium chromate alternative for heavy metal-contg. zinc phosphate-based pigments Toxicology Nontoxic Sibrid TC [Gelest]... 

More complex bis-silanes are being considered as replacements for conventional metal pre-treatment and for chromate in corrosion-inhibiting primers, van Ooij advocates the use of both mono- and di-amino based bis-silanes (see Silanes as metal pre-treatments) ... 

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