Chemistry of Long Wear Inhibition of Corrosion and Mending

What is Corrosion? v1.0m/section_23/28f7e127eabcc9de2916eefc451f6e03.jpg

What Causes Corrosion -Aggressive oxidative species (oxygen, various anions) -pH -Natural factors (temperature, microorganisms) -Another metal causes galvanic corrosion Anodic index MetalIndex (V) Most Cathodic Gold, solid and plated Gold-platinum alloy-0.00 Rhodium plated on silver-plated copper-0.05 Silver, solid or plated; monel metal. High nickel-copper alloys-0.15 Nickel, solid or plated, titanium an s alloys, Monel-0.30 Copper, solid or plated; low brasses or bronzes; silver solder; German silvery high copper-nickel alloys; nickel-chromium alloys Brass and bronzes-0.40 High brasses and bronzes % chromium type corrosion-resistant steels-0.50 Chromium plated; tin plated; 12% chromium type corrosion-resistant steels-0.60 Tin-plate; tin-lead solder-0.65 Lead, solid or plated; high lead alloys series wrought aluminum-0.75 Iron, wrought, gray or malleable, plain carbon and low alloy steels-0.85 Aluminum, wrought alloys other than 2000 series aluminum, cast alloys of the silicon type-0.90 Aluminum, cast alloys other than silicon type, cadmium, plated and chromate-0.95 Hot-dip-zinc plate; galvanized steel-1.20 Zinc, wrought; zinc-base die-casting alloys; zinc plated-1.25 Magnesium & magnesium-base alloys, cast or wrought-1.75 Beryllium-1.85 Most Anodic Sacrificial Anodes

Microbiologically Influenced Corrosion (MIC) - Deterioration of metals as a result of metabolic activity of microorganisms Bacteria affect carbon steels stainless steels aluminum alloys copper alloys, etc. Where: water, soils with pH 4~9 and temperature 10°C~50°C. What kind of bacteria aerobic or anaerobic (oxygen is toxic to the bacteria) Sulphate reducing bacteria (anaerobic) - ships and offshore steel structures Iron and manganese oxidizing bacteria (aerobic) - stainless steels at welds. How to control/prevent Regular mechanical cleaning if possible Chemical treatment with biocides to control the population of bacteria Complete drainage and dry-storage Alternative: genetically engineered aerobic bacteria thwarting the growth of the usual corrosion-causing bacteria

How to Minimize Corrosion Use non-corroding material when possible - glass - plastics - ceramics Silicon carbide ceramics Glass piping - food - pharma Carbon fiber reinforced plastic (composites) Bridge decks, utility poles

Concrete Protection Main cause: deicing salt (NaCl) Possible solutions: -Sand -Ca/Mg acetates -Protect reinforcing steel rodes with recycled poly(ethylene terephthalate) -Zn glucuronate -CONDUR by Great Barrier Systems (two component high build epoxy hole filler)

Corrosion Resistant Metals and Alloys Limitation: $$$$! Solution Vapor deposition (50 μm) on stainless still surface Monel metal 66.6% Ni 35.1 Cu 20% Cr 29% Ni 2.5% Mo 3.5% Cu

Reagents to Inhibit Corrosion Inhibitors act by different mechanisms: - Forming metal complex with altered electrochemical potential -Prevent penetration of aggressive ions -Formation of passivating layer -Inhibition of oxygen diffusion -… and, of cause, protective coating Chromate ion For steel protection Replacements: Cr, Mg compounds Silanes (trimethylsilanes) Alkylphosphonic acids Organic hydrophobic compounds (fatty amines, amine coordinates with M, etc.) Polymer coatings

Mending Polyurethane Coating Could Make Self- Healing Car Paint Textile Surfaces

The Future -Chemistry: Stronger, more durable materials -Society: reduce overconsumption (cost/use approach)

afting-sustainable-consumption-patterns-nokias-ecosystem-approach