References: Tucson SFC

www.wikipedia.org, www.ihccorp.com,

www.essor tment.com, www.wmrc.uiuc.edu,

www.saf.com, www.cheresources.com

Thank you all, helped me in preparing this presentation

PASSIVATIONPassivation is the process of making a material "passive" in relation to another material prior to using the materials together.

For example, prior to storing hydrogen peroxide in an aluminiumcontainer, the container can be passivated by rinsing it with a dilute solution of nitric acid and peroxidealternating with deionized water.

In the context of corrosion, passivation is the spontaneous formation of a hard non-reactive surface film that inhibits further corrosion. This layer is usually an oxide or nitride that is a few atoms thick.

Passivation of specific materialsAluminium may be protected from oxidation by ANODIZING or ALODINING.

Iron based (ferrous) materials, including steel, may be somewhat protected by promoting oxidation ("rust") and then converting the oxidation to a metalophosphate by using phosphoric acid and further protected by surface coating. Rationale for passivating aluminiumAluminium naturally forms an oxide almost immediately that protects it from further oxidation in many environments. This naturally-occurring oxide provides no protection during exposure to any saltwater spray environments, such as occurs in areas near bodies of saltwater. In such coastal environments, unprotected aluminium will turn white, corrode, and largely vanish over periods of exposure as short as a few years. The only way to prevent this from occurring is to use a more robust conversion coating on aluminium surfaces that will not be affected by the saltwater atmosphere. Alodine, Iridite, and chem film coatings can provide varying amounts of protection for aluminium surfaces.

SURFACE EXPOSED

Alodining is the chemical application of a protective chromate conversion coating on aluminum. Alodine is a nonelectrolytic process used to create a chrome oxide film similar to anodizing.

ALODINING (CONVERSION COAT)

It provides good corrosion protection. It even protects when scratched. Alodined 2024 aluminum withstands salt spray 150-600 hours before forming white corrosion. Untreated 2024 corrodes in less than 24 hours.

It provides an excellent electrically conductive surface. This helps to provide good electrical bonding in an airframe.

Paint sticks to it extremely well. In some cases, it can substitute for primer.

Advantages

Adds no measurable weight. Does not alter the dimensions of parts (does not make holes smaller). Requires essentially no cleanup after application. Encourages treatment

of all small parts as they are fabricated and installed.

Requires no electricity or skill to apply.

Disadvantages

Little or no abrasion resistance Should not be applied if the tank temperature is below 70 F (21 C). The alodined surface is not as durable as anodizing or a good paint. Assembled parts cannot be alodined. (Neither can they be anodized.) Disposal of spent tank contents can be a problem.

Alodined parts

Before Alodining

After Alodining

TANKS CONTAINING ALODINE AND DEIONISED WATER

IMMERSING THE PART INTO ALODINE

AFTER REMOVING FROM ALODINE TANK

RINSING IN WATER

MAK ING PART AIR DRY

If the part is bigger than tank size, brush it with alodine and then rinse it in the deionised water.

Aluminum anodizing is the electrochemical process by which aluminum is converted into aluminum oxide on the surface of a part. This coating is desirable in specific applications due to the following properties:1. Increased corrosion resistance 2. Increased durability / wear resistance 3. Ability to be colored through dying 4. Electrical insulation 5. Excellent base or primer for secondary coatings 6. Maintains the original texture when we go for non-dyed anodizing.

The process of anodizing is rather simple. It consists of an anodizing solution typically made up of sulfuric acid/ chromic acid. A cathode is connected to the negative terminal of a voltage source and placed in the solution. An aluminum component is connected to the positive terminal of the voltage source and also place in the solution. When the circuit is turned on the oxygen in the anodizing solution will be liberated from the water molecules and combine with the aluminum on the part forming an aluminum oxide coating.

ANODIZING

When we anodize a part we do not need priming, because it itself is a final finish.

Chromic Acid Anodize: Type ISulfuric Acid Anodize: Type IIHard coat Anodize: Type III

Each of these "types" are then sealedNon-Dyed Seals Class 1Dyed Seals Class 2

Types of Anodizing

Chromic Anodizing {Type I anodize}.

Produced in dilute Chromic Acid solution, this anodize provides a thin film approx 2 m thickness and will produce a clear to gray coating, depending on sealing and alloy used. One third of the coating thickness will build up per surface and 2/3 will be penetration. Since only 1/3 of the thickness is "growth" Chromic Anodize is an excellent choice for Close Fitting assemblies.

Type I Coatings arenot as durable as other anodic coatings. Due to the thin f ilm they also are less capable of accepting dyes.

Chromic acid is carcinogenic and its use is harmful to the environment, so is nearly obsolete.

Advantages

Good Corrosion Resistance (336 hrs salt spray} Excellent Pre-treatment for Paints Good Electrical Resistance Minimum Metal Fatigue Anti-Galling for Close Fitting Assembly

Limitations

SULFURIC ANODIZE: {Type I I Coatings}Sulfuric anodize, commonly referred to as Type II anodizing, is formed by using an electrolytic solution of sulfuric acid at room temperature and a current density of 15 to 22 Amps per square foot. The process will run for 30 to 60 minutes depending on the alloy used. This will produce a generally clear coating, depending on sealing, a minimum of 8 m thick. One third of the coating thickness will build up per surface and 2/3 will be penetration.

Good Corrosion Resistance (336 hrs salt spray) Improved Wear and Anti-Galling Properties. Can bedyed to avariety of colors. Electrical Insulation Properties

Advantages

Limitations

Durability is moderate when compared to hard coat anodizing.

Black anodizedClear anodized (non dyed)

Few examples

Superior Corrosion Resistance (336 ++ hrs salt spray) Superior Wear and Anti-Galling Properties Electrical Insulation Properties User Designated Coating Thickness Unique "Half growth / Half penetration" simplifies engineering for close

tolerance parts Subsequent option to Grind or Lap surfaces to exacting tolerances TEFLON treatments to improve lubricity

Advantages

Limitations

Hard coat anodize coatings may be dyed a variety of colors. However, due to its naturally darker appearance, dyeing does not produce the vibrant colors that a Type II sulfuric anodize will.

Additionally, the required sealing process after dyeing does slightly reduce hardness.

Hard coated parts

Hard coat anodize, commonly referred to as Type III anodizing, is formed by using an electrolytic solution of sulfuric acid at approximately 32 F and a current density of 23 to 37 Amps per square foot. The process will run for 20 to 120 minutes depending on the alloy used and desired coating thickness. This will produce a generally gray coating 10 m to 50 m thick with 50% buildup and 50% penetration.

HARDCOAT. {Type I I I Coatings}

Passivation of Stainless Steel

In processing operations such as machining and forming, iron and foreign particles may become imbedded in the surface of a stainless steel part. Stainless steel passivation removes free iron or iron compounds from a stainless steel surface with the use of chemicals; typically an acid solution (such as nitric acid or citric acid) that removes the surface problem but does not affect the stainless steel itself. If these particles are not removed they will appear as rust or oxidation. Passivation will dissolve the particles and allow a thin transparent film to form on the surface.

The process is performed by first cleaning the surface with solvents or an alkaline solution to remove organic or metallic residues. Next, the parts are placed into passivation solutions. The choice for this solution is usually nitric acid. The process is controlled by three key variables: time, temperature, and concentration.

Passivating for stainless means to remove the free iron from thesurface and create a nickel and chrome-rich surface layer that is not as subject to rust (only iron "rusts").

Passivation spray gel for stainless steel

Passivated stainless steel parts

Primers can help create a uniform, long-lasting final coat. The type of paint used, surface to be painted, and specific surface condition determine primer selection.

PRIM ING

To prime or not to prime, that is the question. The answer is almost always yes, if you want a richly colored, uniformly smooth, long-lasting finish.

It may seem to be an unnecessary extra step when tackling a painting project, but priming a surface to be painted can actually save time in the long-run and produce a superior result.

What are the benef its of priming before painting a surface?Primers can help create a beautiful, uniform, and long-lasting final coat by covering stains and discoloration, hiding surface marks and darker colors, sealing porous surfaces, filling and leveling uneven surfaces, and enhancing the color and adherence of the finishing coat of paint.

It should also be kept in mind that the surface properties of primers can deteriorate over time, and thus a primed surface should be painted within one week for maximum performance.

They generally require about four hours to dry, but should be allowed to cure for about 16 hours before the finish coat is applied. Thickness can be controlled by adjusting the opening of the nozzle thru which primer is sprayed.

Examples of primed parts assembled(All green)

Gun for pr imer spray

Rubber plugs to cover the holes

Few of the different primers used in priming

PRIMED PART

Powder coating is a type of dry coating, which is applied as a free-flowing, dry powder.The main difference between a conventional liquid paint and a powder coating is that the powder coating does not require a solvent to keep the binder and filler parts in a liquid suspension form.

Powder coating

Thermoplastic suitable for items requiring a thicker coating where extreme performance requirements are needed; will repeatedly melt when subjected to heat and solidify when cooled; principle resins used are vinyl, nylon, and fluoropolymers.

Thermosetting decorative, protective, and thinner coatings; undergo an irreversible chemicalchange during cure; principle resins used are epoxy, polyester and acrylic.

The powder may be a thermoplastic or a thermo set polymer. It is usually used to create a hard finish that is tougher than conventional paint. Powder coating is mainly used for coating of metals, such as "white goods", aluminum extrusions, and automobile and motorcycleparts. Newer technologies allow other materials, such as MDF (medium-density fiberboard), to be powder coated using different methods. Thickness can be controlled by measuring with a digital meter after a while during spraying.

Pretreatment: 1.Abrasive cleaning of parts

2.Conversion coating for aluminum parts

Application of PowderThe application of powder is very simple. Filtered, compressed air, usually at 20-30 psi (137-207 kPa) pushes the powder out of the gun past the electrode which gives the powder a positive charge. The part being coated is grounded so the positive powder particles are attracted to it. When the part is completely covered, the ground is taken off and the part is put into the oven.

OVEN

Parts hanged are getting powder coated

Near view of powder coat spray

Part is Grounded

Spray gunSPRAY BOOTH SPRAY BOOTH GROOUNDED WIRE

PART PREPARED FOR POWDER COATING

HANGING METAL HOOKS

PARTS READY

Has powder manufacturing limitations: Difficult to make small amounts Control of texture size and distribution limited Metallic powder coatings not as attractive as wet metallic finishes

While it is relatively easy to apply thick coatings which have smooth, texture-free surfaces, it is not as easy to apply smooth thin films. Is difficult to achieve thin films below 1.0-1.5 mils (1mil =.001 inch). As the film thickness is reduced, the film becomes more and moreorange peeled in texture due to the particle size and TG (glass transition temperature) of the powder.

Limitations

There are several advantages of powder coating over conventional liquid coatings: Has good corrosion resistance. Powder coatings emit zero or near zero volatile organic compounds (VOC)(HARMFUL GASES). Powder coatings can produce much thicker coatings than conventional liquid coatings without

running or sagging. Powder coating overspray can be recycled and thus it is possible to achieve nearly 100% use of the

coating. Powder coating production lines produce less hazardous waste than conventional liquid coatings. Capital equipment and operating costs for a powder line are generally less than for conventional

liquid lines. Powder coated items generally have fewer appearance differences between horizontally coated

surfaces and vertically coated surfaces than liquid coated items. A wide range of specialty effects is easily accomplished which would be impossible to achieve

with other coating processes.

Advantages

Here is an example of Powder coat application. The Edge Trim, Split Lineand Edge Trim shown here are powder coated to match the Tedlar texture in the bottom of Privacy Surround.

Edge Trim, Split Line Privacy Surround Privacy Surround

Edge Trim

Rub StripTedlar

Edge Trim, Split Line

Edge Trim, Split Line

Different Upholstery products

Gros point

FWD Line Assy Emirates 777 Suitor British airways

Gros pointGros point

Soft metal fabric

Covered inside of the Privacy surround of KF suite

Tedlar

Soft metal fabric

Ultra Leather

Kingfisher suite

Ultra leather used in KF and QFA

K ing Fisher suite Qantas

Ultra leather

Emirates

Ultra leather Emirates

Ultra leather King fisher

Tedlar- KF

Tedlar

Tedlars used in King fisher

Used inside suite

Used outside suite

Tedlars used in Qantas

Closet

Privacy surround

Ultra suedeused in Emirates

With texture

Plain

Silk fabric used as outside covering sheet in Jet airways only

Carpet material Normal leather used for seat in KF