Corrosion

[: Rust is a general term for a series of iron oxides. The term is applied to red oxides, formed by the reaction of iron and oxygen in the presence of water or air moisture. Rust consists of hydrated iron oxides Fe2O3•nH2O and iron oxide-hydroxide (Fe O (OH), Fe (OH) 3). Given sufficient time, oxygen, and water, any iron mass will eventually convert entirely to rust and disintegrate] [1]



Iron (or steel) rusting is an example of corrosion, which is an electrochemical process Rust is the common name for a very common compound, iron oxide. Iron oxide, the chemical Fe2O3, is common because iron combines very readily with oxygen, so readily in fact, that pure iron is only rarely found in nature. For iron to become iron oxide (FeO), three things are required: the iron itself, moisture and oxygen.



Road Salt



One of the surest signs of winter in cold-weather regions of the United States is the build-up of salt in tire treads and on roads (and on your boots, and in your house…). The concept of salt-lining roads is easily explained: when you add salt to water, its freezing point dips below the normal 32 degrees Fahrenheit, so the outdoor temperature has to dip even lower than that for ice to form on the roads.



Although dry salt is inert 15 – 20.oF (9 – 29.oC) is considered the lower limit for salt to melt snow and ice but once H2O, even in the form of moist air (i.e. humidity) is added the freezing point is lowered and the sprayed brine solution (pH 8.5) used on roads will have an adverse effect (the formation of rust and/or corrosion) on the vehicles paint and undercarriage. When washing the vehicle ensure that all salt removed to avoid a brine solution remaining on the paint finish. Using a durable protection (Collinite Insulator Wax) will provide a sacrificial and renewable protection to the vehicles paint finish.



Nearly all highway de-icers on the market are made from one, or a blend of, five materials — calcium chloride (CaCl2) sodium chloride (NaCl) potassium chloride, magnesium chloride (MgCl2) and urea. What makes these products different is how quickly they work and at what temperatures. This is determined by whether the de-icer releases or absorbs heat upon contact with snow and ice.



Exothermic de-icers - which release heat to melt the ice, work the quickest and are effective at a broader range of temperatures. For example, solid calcium chloride releases heat and is effective down to –25.oF. Endothermic de-icers, which absorb the sun’s heat and use it to break ice down to liquid brine, work more slowly and are effective at a smaller range of temperatures For example, solid sodium chloride absorbs heat and is effective down to about 20.oF. The predominant chemical in a blended product will determine its performance.



The salts (salt CI and water H2O produce oxides, which cause corrosion) used for freezing point depression in a sprayed brine solution (often mixed with grit / sand for tyre adhesion) commonly used are;



(a) Sodium chloride (NaCl) the most common salt used Sodium chloride (rock salt, halite) Calcium chloride is thought to be more environmentally friendly than sodium chloride when used to de-ice roads, however a drawback is that it tends to promote corrosion (of vehicles) more so than sodium chloride. NaCl is also more readily available and does not have any special handling or storage requirements, unlike calcium chloride. Lowest practical temp: 15.oF (9°.C) keeps sidewalks dry, corrosive, damages to concrete and vegetation



(b) Calcium chloride (CaCl2) works at lower temperatures than sodium chloride. Calcium chloride is preferred over sodium chloride, since it releases energy upon forming a solution with water; heating any ice or snow it is in contact with. It also lowers the freezing point, depending on the concentration. Lowest practical temp: 20.o F (29. °C) melts ice faster than sodium chloride, attracts moisture, surfaces slippery below



(c) Magnesium chloride (MgCl2) is the name for the chemical compounds and its various hydrates MgCl2 (H2O) x. These salts are typical ionic halides, being highly soluble in water. Melts ice faster than sodium chloride. Lowest practical temp: 5. °F (15°.C) attracts moisture



Magnesium chloride is very effective even at the lowest temperatures but also contains the most aggressive corrosives (especially on glass surfaces) and a sprayed brine solution, it is used to prevent snow / ice adhesion to the road surface. A number of state highway departments throughout the United States have decreased the use of rock salt and sand on roadways and have increased the use of solutions of magnesium chloride (often called "liquid magnesium chloride") as a de-icer. Magnesium chloride is much less toxic to plant life surrounding highways and airports, and is less corrosive to concrete and steel (and other iron alloys) than sodium chloride.



Anti-icing liquids, which according to State authorities, the liquid solution consists of - Magnesium chloride (MgCl2) Calcium chloride (CaCl2) and other liquids that work like anti-freeze, by lowering the freezing temperature of water and preventing ice from forming a strong bond to the road



Some areas have made inventive alterations to basic rock salt: many civil engineers have long added sugar beet molasses to their road salt to make sure it stays where it’s supposed to, the stickiness of the molasses keeps the salt on roads longer, saving money by reducing the number of times each town has to salt. The mixture is also supposed to be less corrosive than the plain rock salt that is normally used, and it reduces the environmentally damaging concentration of salt on the road (too much salt makes for briny groundwater, which can end up dehydrating plants and killing aquatic life).



Removing Salt from Paint Surfaces



Road salt is difficult to remove from vehicle paint surfaces as many State authorities use an additive based on molasses, a bye product of the sugar refining industry, along with the salt solution to ensure it adheres and is therefore more effective. Use a high pressure hose (Power wash) the wheel wells and undercarriage, and allow to dry. Spray the affected area (s) with Eastwoods Road Salt Neutralizer a high performance rust-preventive coating designed for application directly on rusted metal surfaces; apply thin coats and allow each coat to thoroughly dry



Waterless polymer based systems, like Optimum no rinse (ONR) does not require pre-wetting the surfaces, it’s a combination of polymers and surfactant cleaners that encapsulate and safely remove salt, dirt and grime and leave a glossy protective finish. The polymers and surfactants used in these no rinse washes have the capability to bond to dirt particles and act as a barrier between the dirt particles and the paint. The salt, grime and dirt are then trapped in the surfactant, protecting the paint finish with no need to use a large amount of water to flush the dirt off the vehicle.



Kärchar K5.700 Pressure Washer- effortlessly cuts through dirt and grime and is convenient to use. Features include a long-life water-cooled induction motor that is light, powerful and energy-efficient. Features include a variable detergent regulator and innovative Plug `n` Clean system - for quick and convenient detergent changeovers. Other features include Quick Connect hose, integrated hose reel and on-board practical accessory storage.



An impact-resistant, recyclable plastic casing effectively prevents dirt particles from damaging the motor and pump. A safety valve prevents pressure overload.

Long-life, aluminium three-piston axial-flow pump, corrosion-resistant, maintenance-free and energy efficient, a pressure switch control switches the motor on and off when the trigger gun is pressed and released. A large on/off switch and an ergonomically



High Pressure Under- body Lance



Angled spray lance specifically designed to clean those hard to reach areas under the wheel arches and the under carriage, compatible with all Kärcher domestic pressure washers.



Methodology



1. Thoroughly spray an undiluted citrus cleaner (P2IS Total Auto Wash) and let it soak in; remove by thoroughly rinsing with water. If you have a pressure washer available, fill tank with citrus cleaner and spray undercarriage (do not use excess pressure as water may penetrate crevices and seams where it cannot drain, causing corrosion), let it soak and then remove with plain water.



2. Spray undercarriage with (ValuGard Alkaline Neutralizer or Eastwoods Road Salt Neutralizer), which deep cleans painted surfaces to remove alkaline deposits and safely dissolves the alkaline salt particles bond with the paint so that they can be rinsed away. Allow product to remain in place for 5-7 minutes. All necessary safety precautions should be taken whilst using these products





3. Rinse vehicle undercarriage



4. Protection - apply a coating of Bilt-Hamber Laboratories - Dynax UC a high performance rust-preventive coating designed for application directly on metal surfaces; apply thin coats and allow each coat to thoroughly dry





Alternative product

1. Wurth High Build Underbody Spray produces a jet black, textured finish in wheel wells and on lower rocker panels. This spray will hide a multitude of blemishes and make old wheel wells look factory new. Provides permanent yet flexible protection against flying stones, rust, water and road salts



2. Wurth SKS Stone Guard matches OEM Factory applied stone protection on vehicles such as BMW, Fiat, Mercedes-Benz, Porsche and Renault; for use on door sills, front and rear body parts, mudguards, under bodies, rocker panels, etc. Stone Guard is a water based product and offers easy clean-up, its paintable and can be top coated with solvent based urethane or water-based top coats (available in Black or Grey)



Road Salt Stains - are usually caused by calcium chloride and magnesium chloride. Use a stiff brush to dislodge any loose road salt and then vacuum, spray the area with a carpet cleaner and let it soak in, rinse with plenty of water and repeat until most of the stain has been lifted. Finally clean carpets by spraying the area with a carpet shampoo rinse and then remove with a carpet extractor.

(Dry) Salt is inert but be aware that once you add water ( by meting the snow / ice ) to salt it becomes alkaline (corrosive) take care to dry the affected area thoroughly after the salt has been removed and neutralize it with an mild acid (vinegar) Spray vinegar, agitate, allow to remain in place and then use an extractor. Actually, any mildly acidic product should neutralize alkaline salt crystals (Salt-X)



Note: Once you add reactivity (heat) and water this combination makes salt very corrosive



Removing Road Salt (Carpets and Mats)



Once the product has been tracked in, however, it needs to be cleaned up in a timely manner. Use a vacuum or a mop to clean up sodium chloride products. Mop up calcium chloride or magnesium chloride ice met with a good detergent. If dirt has been tracked in with a de-icer, a mildly acidic cleaning agent works best. Carpets damaged by tracked-in residue will typically require professional cleaning.



Use a stiff brush to dislodge any loose road salt and then remove with a vacuum, spray the area with a carpet cleaner and let it soak in, the salt stains are highly alkaline once mixed with water, so I`d reach for an acidic product to counteract/neutralize. You might find that rinsing with a solution of vinegar /water helps. Repeat until most of the stain has been lifted.



Finally clean carpets by spraying the area with a carpet shampoo or P21S Total Auto Wash and then rinse and remove with a carpet extractor. Using the vacuum, remove the excess moisture, loose dirt and the grime, allow carpets / mats to thoroughly dry before use, and then apply a fabric protection (303TM High Tech Fabric Guard) Be aware that once you add water to salt it becomes corrosive, so take care to dry the affected area thoroughly (inc the area underneath the carpet / backing) after the salt has been removed.



Removable floor mats; use a pressure washer or hose to get them clean. Deep scrubbing with lots of water and soap works well, then use the pressure washer or the jet nozzle on the hose to rinse the mats. Ensue you thoroughly rinse the mats to remove all soap residue; otherwise they will attract dirt and will become stiff.



Rust Removal / Treatment



Careful sand blasting is the best method for removing medium to heavy rust but you need to be careful not to warp the sheet metal. The metal can be sanded to remove surface rust but if it`s pitted you`ll need to use a metal conditioner/rust converter to stabilize the surface before priming. If you use a product like Picklex 20 to stabilize the rust you want to make sure you work it into the surface with a scuff pad then wipe it off after a minute or two and coat with an acid free, direct to metal primer like epoxy primer that doesn’t’ contain any acids. If you plan on leaving the metal without primer for any length of time the Picklex 20 will protect it from flash rusting as long as it doesn`t get wet.



Rust Prevention



A British company Bilt-Hamber Laboratories has a new product - Dynax UC new high-performance anti-corrosion wax provides a touch-dry firm wax film that`s virtually invisible, a low film thickness see-through protective shield. Its firm wax like film is rich in unique metal seeking corrosion inhibitors that stop existing and prevent new corrosion. It can be applied to bare metal or painted surfaces in fact anywhere where a discrete and powerful inhibitor is needed.



This product is aimed at those that want a see-through tack-free film that adds a lot of corrosion protection but preserves the factory look of the underside or lower panels, it’s removable too, so after winter it can be stripped if required, or left in situ and topped up every couple of years, or more if you wish; very easy to use.



Completely safe to use on the vast majority of paint coatings and is ideal where dark colored waxes or under seal would detract from the painted finish of vehicle bodywork or underside.



The touch dry tough wax film also provides mechanical protection to the protected surface too. The ideal product to provide high levels of protection during the winter months; to apply -clean any loose dirt, rust flakes or other debris and then clean with a power-washer, allow product to dry and then apply thin even coating