Metals surface preparation

Many test results and a great deal of engineering data over many years have shown that the most important single factor influencing the life of a paint is the proper preparation of the metal surface. This factor is, generally, more important than the quality of the paint that is applied. In other words, a poor paint system on a properly prepared metal surface usually outperforms a better paint system on a poorly prepared surface. A well-prepared surface is the foundation on which the paint system is built. 

Adequate surface preparation consists of two main processes. 

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Despite the progress outlined in this chapter, much work remains to be done in the metal surface preparation arena. For example, there is still no ideal surface preparation method that does for steel what anodization processes do for aluminum and titanium. The plasma spray process looks encouraging but because it is slow for large areas and requires rather expensive robot controlled plasma spray equipment, its use will probably be limited to some rather special applications. For more general use, the sol-gel process has potential if future studies confirm recently reported results. 

Nature of the metal surface Clean, smooth, metal surfaces usually require a lower concentration of inhibitor for protection than do rough or dirty surfaces. Relative figures for minimum concentrations of benzoate, chromate and nitrite necessary to inhibit the corrosion of mild steel with various types of surface finish have been given in a recent laboratory studyThese results show that benzoate effectiveness is particularly susceptible to surface preparation. It is unwise, therefore, to apply results obtained in laboratory studies with one type of metal surface preparation to other surfaces in practical conditions. The presence of oil, grease or corrosion products on metal surfaces will also affect the concentration of inhibitor required with the... 

Wastewater from porcelain enameling on steel is generated by base metal surface preparation, enamel application, ball milling, and related operations. The constituents in the wastewater include the base material being coated (iron), as well as the components of the surface treatment solutions and enamels being applied. 

Review of recent state resolved experiments exploring thermal and laser driven desorption processes at metal surfaces. (Prepared January, 1988)... 

Advantages and Disadvantages of Metal Surfaces Prepared by Different Methods... 

Chen JG (1996) Carbide and nitride overlayers on early transition metal surfaces preparation, characterization, and reactivities. Chem Rev 96 1477... 

Physical and Electronic Properties of Oxides Methods of Metal Surface Preparation Conducting Polymers for Corrosion... 

The overall program results indicate that good quality structural bonds (titanium-to-titanium) can be produced which exhibit durability to supersonic cruise vehicle environments. LARC-TPI demonstrated the best overall properties of all systems evaluated. PPQ with proper metal surface preparation could possibly also perform as desired in these environments. 

Metal treatments and cleaners Industrial Metal surface preparation, coating, residue removal, paint removal, etc. 

Resistance to filiform corrosion depends more on factors such as the environment, the type and thickness of coating, metal surface preparation, and coating apphcation procedures than on the metal itself. However, there is evidence that higher copper content aluminum alloys are more susceptible. Primary environmental factors are the presence of moisture and chloride ions. An acidic electrolyte has an accelerating effect. 

Metal surface preparation processes and paint evaluation... 

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). 

There are a few other materials that need to be covered for this discussion. The first is solder paste. This is a mixture of minute solder beads, flux, and other materials to give it specific rheological characteristics for dispensing and chemical agents for metal surface preparation. For surface-mount applications, it is typically stenciled onto PWB bonding pads, and then the electronic component is placed upon the solder paste deposit. The paste holds the component in place during the reflow process.The second is flux, which, as mentioned previously, is a key component of solder paste. The flux is a heat-activated chemical agent used to clean solder-able surfaces. Both paste and flux will be covered in subsequent sections of this chapter. 

Table 7.8 shows the effect of various metallic-surface preparations on adhesive-joint strength. 

Figure 3. Results of metal surface preparation tests...

Structural Adhesives. Films of nitrile rubber/phenolic resins (i.e. tapes) have been employed in the aircraft industry for bonding metal to metal surfaces in both plain and honeycomb sandwich constructions. Several Wright Air Development Center reports " describe in detail the preparation of a nitrile rubber/phenolic resin tape, the metal surface preparation methods, and the methods of evaluating structural adhesives of this type. A formulation for a high-temperature liquid phenolic resin adhesive suitable for structural fabrication is given in Table 21. ... 

The test specimens for this program were of the standard lap-shear t5q)e having a 1-in. width and a Vi-in. overlap length. Lap-joint panels 7 2 by 14 in. were fabricated by overlappingandbonding0.063-in.-thicksheets of clad 2024-T3 aluminum alloy or 301,1/2H, 2B-finish stainless steel. Manufacturer s recommendations were followed for metal surface preparation and adhesive bonding. After curing, the panels,were cut into 10 test specimens each of 1-in. width and... 

If more than one metal is involved, galvanic corrosion is a possibility and the ratio of areas of the metals will dictate intensity of attack on the anodic metal. Surface preparation of the specimens may be effected in different ways. 

Uemura, S. Sakata, M. Hirayama, C. Kunitake, M. 2004. Fullerene adlayers on various single-crystal metal surfaces prepared by transfer from L films. Langmuir 20 9198-9201. 

With the arrival of composites, the issue of assembling composite and metal parts together was brought sharply into focus. If the resin formulators went a significant way to meeting requirements (mechanical, thermal), dedicated metal surface preparation prior to bonding had to be developed, most of the metals being subject to surface corrosion with the production of brittle oxides, especially the aluminum alloy ones. 

Metal Surface preparation Surface temperature (K) Emissivity, total normaP... 

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