Surface preparation of aluminum

E 229 E 864 Test Method for Shear Strength and Shear Modulus of Structural Adhesives Practice for Surface Preparation of Aluminum Alloys to be Adhesively Bonded in Honeycomb Shelter Panels... 

Much work has been done concerning the surface preparation of aluminum for adhesive bonding in the aerospace industry. Bethune (11) described the evolution of surface treatments from the FPL-etch (H2S0 /Cr02) to the... 

Russell, W.J. and W.C. Tanner, Component Parts Assembly with Joints Adhesive-Mechanical, Part 1. Surface Preparation of Aluminum for Weldbonding, Picatinny Arsenal Technical Report (PATR) 4610, AD 919 514L, February 1974. 

ASTM D2674-72 (1998) Standard methods of analysis of sulfochromate etch solution used in surface preparation of aluminum. 

Analysis of Sulfochromate Etch Solution Used in Surface Preparation of Aluminum, Methods of (D 2674)... 

Several surface preparations of aluminum are widely used in the aircraft industry. " The important steps in all surface preparations are vapor degrease, alkaline clean, rinse with water, chromic acid etch (FPL Etch), rinse with water, anodize with chromic acid or phosphoric acid, rinse with water, and dry at 140-160°F. Details of the procedures for the surface preparation of aluminum and other metals and composites are available from a number of sources. 

Phosphoric acid anodization (PAA)( > is a common method of surface preparation of aluminum adherends prior to adhesive bonding for aerospace applications. PA A surfaces are microscopically rough(6) and are more resistant to hydration than aluminum surfaces prepared by other treatments.(2,90) The microroughness provides for mechanical interlocking with the primer or adhesive, which results in a strong adhesive bond, while the environmental stability of the oxide (together with its porosity) results in excellent bond durability in hot, humid environments. 

TABLE 7.11 Surface Preparation of Aluminum Substrates vs. Lap-Shear Strength (from Ref. 12)... 

The surface preparation of aluminum before fitting, such as painting and bonding, is mandatory because of aluminum alloys offer high sensitivity to superficial oxidation with... 

ASTM D3933, Standard Guide for Preparation of Aluminum Surfaces for Structural Adhesives Bonding, Phosphoric Acid Anodization, A.STM, West Conshohocken, PA. El-Mashri, S.M., Jones, R.G. and Forty, A.J., Philo.s. Mag. A, 48, 665 (1983). 

Effects on lap shear strength of EB-cured epoxy adhesives from different surface preparations on aluminum and composite adherends... 

The surface preparation operations for strip are dependent upon whether the basis material is steel or aluminum. The surface preparation steps for steel strip are minimal in comparison to porcelain enameling on steel sheets because precleaned strip steel is used. Steel strip is nickel immersion plated prior to the enameling step. Surface preparation for aluminum involves only cleaning. The enamel for either basis material is applied by means of spray guns that are aimed at the surface of the moving strip. Two coats are normally applied, the strip being fired after each coat. 

Substrate Characterization. Test coupons and panels of 7075-T6 aluminum, an alloy used extensively for aircraft structures, were degreased In a commercial alkaline cleaning solution and rinsed In distilled, deionized water. The samples were then subjected to either a standard Forest Products Laboratories (FPL) treatment ( 0 or to a sulfuric acid anodization (SAA) process (10% H2SO4, v/v 15V 20 min), two methods used for surface preparation of aircraft structural components. The metal surfaces were examined by scanning transmission electron microscopy (STEM) In the SEM mode and by X-ray photoelectron spectroscopy (XPS). 

A saturated solution of aluminum sulfate is employed as a mild caustic. Solutions containing 5-10% aluminum sulfate have been used as local applications to ulcers and to arrest foul discharges from mucous surfaces. Aluminum sulfate is also used in the preparation of aluminum acetate ear drops (HSDB 1995). With respect to use application, about 65% of the aluminum sulfate produced is used for water and sewage treatment (HSDB 1995). 

Generally only solvent cleaning and abrasion are necessary for surface preparation of polystyrene parts. Methanol and isopropanol are acceptable solvents for solvent cleaning of polystyrene. For maximum bond strength the substrates can be etched with sodium dichromate-sulfuric acid solution at elevated temperature. Table 16.14 shows the results of a study on the durability of joints formed between polystyrene and aluminum with different types of adhesives exposed to different environments. 

D 3933 Practice for Preparation of Aluminum Surface for Structural Adhesive Bonding... 

All of the compounds used or prepared in this work are spoiled by water. All transfer of materials was therefore carried out either in the dry atmosphere of a Vacuum Atmospheres Corp., DRILAB, or by distillation under vacuum in well-dried apparatus. All containers or exposed surfaces were of aluminum, Monel, Kel-F, Teflon or quartz. Vacuum lines were constructed of Autoclave Engineering 30VM6071 Monel valves (rated to 30,000 psl) and appropriate lines and connectors. Normal working pressures were measured with Monel Helicoid gauges — one for the 0-1500 torr range, and another for the 0-500 psi range. 

Traditionally, anionic surfactants have offered better detergency then nonionics, but were not compatible in acid systems. This formulation uses Avanel S-70, an anionic molecule which performs even at very low pH s and aids in the removal of surface oils and deposits. Unlike nonionics, Avanel S-70 will dissolve readily into the formulation without forming gel particles thus eliminating the need for excessive agitation. This formulation can be used for over-the-road aluminum trailers, wire wheels on automobiles or in the preparation of aluminum for anodizing and cleaning. 

In addition to the effect of the chemistry and the physical properties of the adhesives, the surface preparation of the adherend also has a marked effect. Aluminum surface treatments vary from simple solvent wiping to anodization. Steel treatments vary from abrasive grit blasting to acid etching. In general, it is found that the better the initial surface preparation, the more durable the bond. 

Bonder, B.B., Preparation of aluminum alloy surfaces for sport weld bonding. Proceedings of the 7th National SAMPE Technical Conference, Vol. 7, Albuquerque, New Mexico, pp. 374-385. 

ASTM D3933-98 Standard practice for preparation of aluminum surfaces for structural adhesive bonding (phosphoric acid anodizing). 

Preparation of Aluminum Surfaces for Structural Adhesive Bonding (Phosphoric Add Anodizing), Practice for (D 3933)... 

Urine must be voided directly into specially cleaned plastic containers. Tissue and bone specimens must be placed in an Al-free container. Several methods (nitric acid, nitric acid in Triton X-KX), EDTA solution) are available for the preparation of aluminum-free plastic and glassware [21,31,32]. On the other hand, considerable losses of aluminum will occur as a result of adsorption when aqueous solutions come into contact with glass surfaces. 

Aluminum is painted for both protective and decorative purposes. As with any metal, surface preparation is extremely important. Conversion coatings, either of the chromate or phosphate type, are recommended for the preparation of aluminum alloys. In environments containing chlorides a chromated primer should be applied first. Water base paints are particularly suitable for use with aluminum alloys (see Chapter 7). 

Chessin, N., and V. Curran, Preparation of Aluminum Surface for Bonding, in M. J. Bodnar, BA., Structural Adhesive Bonding, Interscience, New York, 1966. 

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