Rust converters

Water-borne rust converting primer 43 50-75 30 min 6-8 h For lightly rusted steel, eliminates the need for blasting, suitable for epoxy topcoats... 

Film-forming anions (phosphates, polyphosphates, and carbonates) can also form sparingly soluble salts on the metal surface that hamper corrosion propagation. These anions can become an active part of rust converters that transform corrosion products into insoluble compounds. For instance, orthophosphoric acid transforms rust into insoluble iron phosphates. 

Several so-called rust-stabilizing or rust-converting products are commercially available, but the practical efficiency of these products depends on the conditions. They are made for coating on rusty substrates, but it is still important to remove loose rust, which can be done by thorough steel brushing. Some products are based on phosphoric acid. These must be applied in appropriate thickness, and excessive acid must be washed away with fresh water before the coating is overpainted. 

Chem. Descrip. Vinylidene chloride acrylic copolymer emulsion Uses Vinylidene chloride-acrylic for maintenance primers, rust converting coatings, underbody/under hood coatings, barrier coatings Features Provides exceptionally low moisture vapor transmission rate, exceptional corrosion and humidity resist., exc. adhesion Properties Emulsion dens, 9.7 Ib/gal vise. 30 cps pH 1.5 hardness (Konig) 30 57.5% NV by wt. 

Chem. Descrip. Vinylidene chloride acrylic copolymer emulsion Uses Vinylidene chloride-acrylic for coatings, maintenance primers, rust converting coatings, underbody/under hood coatings and barrier coatings... 

With resin-based repair mortars the reinforcement bars should be gritblasted and the system applied within four hours. Otherwise a non zinc-rich holding primer may be considered. Rust converters should be treated with caution since some containing phosphoric acid can inhibit cure of the subsequently applied resin. The top coat of any compatible primer or bond coat applied to the substrate concrete or steel bars should still be tacky when the repair mortar is applied. 

Bolivar, F., Meneses, C.A.B., Minotas, J., Greneche, J.M. Variable temperature mossbauer study of some rust converters. Hyperfine Interact 148, 219-225 (2003)... 

Phosphoric acid may be used as a "rust converter", by direct application to rusted iron, steel tools, or surfaces. The phosphoric acid converts reddish-brown iron(ni) oxide (rust) to black ferric phosphate, FeP04. 

Rust converter" is sometimes a greenish liquid suitable for dipping (in the same sort of acid bath as is used for pickling metal), but it is more often formulated as a gel, commonly called naval jelly. It is sometimes sold under other names, such as "rust remover" or "rust killer". As a thick gel, it may be applied to sloping, vertical, or even overhead surfaces. 

A. Collazo, X. R. Novoa, C. Perez, B. Puga, The corrosion protection mechanism of rust converters an electrochemical impedarure spectroscopy study, Electrochim. Acta, 2010,55, pp. 6156-6162. 

Passivation According to Fig. 1.15 (top) all the Fe will be converted to Fe2 03, whilst the rust originally present will be unaffected. According to Fig. 1.15 (bottom) the rust will be unaffected, whilst the iron surface exposed to the solution through pores in the rust will be passivated by a protective film of Fe203. Water will be stable except at high potentials where it will be oxidised to O2. 

In dry air the stability of zinc is remarkable. Once the protective layer of zinc oxide formed initially is complete, the attack ceases. Even under under normal urban conditions, such as those in London, zinc sheet 0 -8 mm thick has been found to have an effective life of 40 years or more when used as a roof covering and no repair has been needed except for mechanical damage. The presence of water does, of course, increase the rate of corrosion when water is present the initial corrosion product is zinc hydroxide, which is then converted by the action of carbon dioxide to a basic zinc carbonate, probably of composition similar to ZnCOj 3Zn(OH)2 . In very damp conditions unprotected zinc sometimes forms a loose and more conspicuous form of corrosion product known as wet storage stain or white rust (see p. 4.171). 

In the presence of oxygen the ferrous hydroxide will be converted into rust, Fe20j.H20. 

For converting rust to clinging layers as a basis for coatings of paint and varnish, the addition of alkyl phosphates to phosphoric acid is suggested to improve its wettability and penetration [260]. 

Rust, Val Dean. Radical origins early Mormon converts and their colonial ancestors. Urbana (IL) Univ of Illinois P, 2004. xi, 253 p. ISBN 0-252-02910-0... 

Soft, silvery metal whose isolation is difficult. Ytterbium fluoride is added to dental fillings (as X-ray contrast agent). Ytterbium is a constituent of rust-free special steels. Yb2Co13Fe3Mn holds the magnetic world record, but is too expensive for commercial purposes. The element is occasionally applied in nuclear medicine and radiography. It also activates phosphors that convert infrared rays into visible light. 

This relationship gives a way of converting from grams to moles to particles and vice versa. If you have any one of the three quantities, you can calculate the other two. For example, the molar mass of iron(III) oxide, Fe203 (rust), is 159.689 g/mol [(2 X 55.846 g/mol for Fe) + (3 X 15.999 g/mol for O)]. Therefore, if we had 50.00 g of iron(III) oxide, we could calculate both the number of moles and the number of particles present. 

Fig. 19.3 FTIR spectram of (a) bare rust and (b) converted rust samples FT-ferric-tannate, G-geothite, L-lepidocrocite, M-magnetite...

Chromate adsorbed from solution by green rust was reduced to Cr with the green rust being simultaneously converted to ferrihydrite or possibly a Cr substituted ferrihydrite (Loyaux-Launiezak et al., 2000). 

The oxidation and hydrolysis of Fe leads to Fe " oxides either directly or via soluble green rust complexes, solid green rusts or Fe(OH)2. The latter convert to the oxides either by a solid state reaction or a via solution (reconstructive) transformation. Generally, where there is a difference between the structure of the precursor and that of the final oxide, a via solution process seems more likely, but internal rearrangement during topochemical oxidation to the new phase, may also take place. 

Sohd iron undergoes rusting by reacting with oxygen in the presence of water (or water vapor). Thus, in moist air, it rapidly converts to rust, which is hydrous iron(III) oxide. The reaction occurs at ordinary temperatures, catalyzed by acid. The overall reaction is ... 

---