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2009 Anodizing Conference Abstracts
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Abstracts for the 2009 Anodizing Conference were organized by General Sessions and the following Focus Sessions: Technical, Technology Forum, and Scientific.

General Sessions

All About Value
Jon Ledin, AaCron, Inc.;
Gary Kriesch, Walgren Company*

The needs and challenges of anodizers may be shared by similarly situated companies and individuals, but may also be unique to the aluminum anodizing industry. Trade associations exist to represent the shared interests of constituents. This presentation reveals some of the benefits of membership in the Aluminum Anodizers Council, the international trade association of the aluminum anodizing industry. Organized in support of the strategic aims of Advocacy, Education, and Promotion, member benefits are designed to foster the success of member companies. Product and process marketing, regulatory response, and trends identification are seen to be areas of common interest ideally supported through a community of practice. The Council is shown to provide the forum in which such a community can thrive.

Anodizing Large-Scale Solar Equipment
Pat Burt, Acteron

Alternative energy sources are seen as a source of new markets for a variety of products. Power generation and distribution systems in the 21st century will demand new infrastructure, and anodized aluminum components ought to a play a significant role. In this presentation, a unique process module system for anodizing large-scale solar equipment will be discussed.

Designing for Opportunity: The Aluminum Advantage
Jude M. Runge, Ph.D., CompCote International, Inc.;
Richard Rosenfield, Douglas Alexandria Finishing, Inc.*

Many industries that require innovative solutions in cost reduction and weight savings are turning to aluminum as a substitute for stainless steel and other steel alloys for parts and components. Aluminum is lighter weight, and many aluminum alloys exhibit high strength-to-weight ratios, which in many applications enable the replacement of stainless steel with considerable weight savings. Furthermore, aluminum is recyclable, and less expensive in both material and fabrication. It is easier to process, and many aluminum extrusions and castings can be produced near net shape, which saves time and money in post-process machining.

The main difference between stainless steel and aluminum is in the inherent corrosion resistance of stainless steel. Stainless steel must be finished when used in wear applications; nickel plating and specialized carburization processes are the typical finishes of choice. However, aluminum and aluminum alloys exhibit long-term corrosion and wear resistance when anodized, which brings new business opportunities for the metal finisher.

This paper presents four examples from four industries that have successfully substituted aluminum for stainless steel and that use the anodized finish for decorative corrosion and wear protection. A case study will also be presented, which compares the corrosion performance of stainless steel, unfinished aluminum and two types of anodized aluminum in a harsh environment that proves the possibility of substitution as an actual viable option.

Whereas 1) many manufacturers have as part of their cost-reduction programs a review of parts and components made with stainless steel to determine if aluminum is a viable option and 2) engineering standards should include the consideration of aluminum as raw material as part of the design process, it is necessary that the metal finisher be aware of the trend to substitute other materials with aluminum and therefore to explore possibilities and opportunities to serve these new markets.

Using Design of Experiments Methodology for Product/Process Development
Tim Cabot, Duralectra-CHN

Customer complaints and dissatisfaction with existing products/processes are a valuable source of ideas for new
product/process development. This presentation will highlight this truism through a real life example and show how one such instance coupled with a Design Of Experiments development methodology created a compelling new business opportunity. Further, the presentation will explore how a key facet of the new process offering was the development of new application test methods targeting the poor performance from which performance standards and specifications for the new finish were developed.

The main objective of the presentation, apart from showing specific techniques and methods that can be used for new product/process development, is to point out that a willingness to confront the root cause of complaints and understand the underlying mechanisms can result in new business opportunities.

What Customers Should Ask and Expect of Their Anodizers
A. D. Juhl, AluConsult

Anodizing, compared to other aluminum surface treatments, is a sustainable choice for your customer’s product because the anodic oxide layer is built from the aluminum substrate: in essence, it is aluminum in its natural form. It is therefore very important to produce work of suitable performance quality, so more end users will choose anodizing.

When the first question from the customer is, “What is the price and when will I have my parts back,” the relationship between the anodizer and customer suffers. One of the most important questions to ask is what properties are needed to get the optimal lifetime for the product. A short overview in this presentation will show the common standards for anodizing.

This presentation also offers a guideline to the questions that customers should ask of anodizers. Though this will not make your customer an expert in anodizing, informing the end-user of what is occurring in the process can serve to create a good partner for future business.

Corrosion of Hard-Anodized Aluminum - A Case Study
Bob Steingass, Task Force Tips

Firefighters depend on the high strength-to-weight ratio of aluminum combined with the corrosion-resistance of anodizing to deliver optimum performance under critical circumstances. The rapid occurrence of corrosion in valves used by a major metropolitan fire department led to the examination of several possible causes. This case study recounts the results of the examination and the recommended mitigation.

Effect of Homogenization and Annealing of 6060 Aluminum Alloy on Optical Properties of Anodic Oxide Film
N. Tabrizian, Technical University of Denmark;*
R. Ambat, Technical University of Denmark;
P. Møller, Technical University of Denmark;
H. N. Hansen, Technical University of Denmark

Homogenization and subsequent annealing treatment was performed on extruded 6060 alloy in order to analyze the effect of resulting microstructure on the quality and appearance of the oxide film formed during a conventional anodizing process. Samples were homogenized at 630 ºC for 10 hours. Annealing was performed at 450 ºC for 24 and 96 hours. Microstructure of the substrate material and oxide film was investigated using optical microscope (LOM) and scanning electron microscope (SEM), and chemical composition analysis using energy dispersive X-ray spectroscopy (EDX). Composition profiling of the anodized layer as a function of depth was carried out using glow discharge optical emission spectroscopy (GDOES). Change in surface roughness of the substrate interface with oxide was analyzed using atomic force microscope (AFM) after stripping the oxide layer.

Results showed that the homogenization treatment did not cause any visible changes on the quality of the anodic film. Annealing has influenced the appearance of the anodic film, however independent of annealing time. Anodized layer formed on annealed sample was non-uniform with traces of more trapped intermetallic particles and other imperfections. GDOES profiling showed a thin layer of oxide (about 50 nm) at the surface had higher amounts of impurity elements. The oxide film formed on the annealed sample appeared to be more porous due to many cracks and cavities detected by SEM. On the other hand, oxide film formed on annealed samples showed to contain a higher amount of Si, which could be due to the higher amount of Si and Mg2Si particles found in the bulk of the annealed samples by EDX. Roughness measurement of the stripped surface showed that the surface of the annealed and homogenized samples were much more smooth compare to the as-received sample. Smoother surface has lower scattering, and therefore defects and impurities are more apparent. Consequently the oxide film formed on the annealed sample appears more flawed due to lower roughness of the surface of the substrate, higher amount of Si and higher imperfections (cracks).

Performance of Acid Etch
Mitch Whitehead, International Extrusion Corp.

It has been more than three years since the introduction of a new acid etch process to the anodizing market, and now the process is widely accepted by anodizers and end users, alike. This session will feature in-depth discussions of acid-etch performance, comparing the main differences between the caustic and acid etch processes from the anodizer’s perspective. Quality of the finished product, chemicals, equipment, and waste treatment also will be addressed.

Optimizing the Extrusion Process for Surface Quality
Duncan Crowdis, Bonnell Aluminum

This presentation will review the impact that various factors within an extrusion operation can have on the surface quality and customer needs of architectural products. Included will be the impact of die design, press handling equipment, metal handling procedures, plant culture and focus and opportunities within the anodizing process.

Aluminum Trends
Jorge Vazquez, Harbor Intelligence
This presentation will review the latest intelligence on key global aluminum market trends, and in this context major trends in the demand for aluminum extrusions in the United States. Additionally, the outlook for demand and prices for 2010-2012 will be covered as well as the trends in the construction, auto, and durable goods sectors.

Focus Session 1: Technical

HC Power
Leonid Lerner, Sanford Process Corporation

Many variations of hard anodizing have been developed to produce coatings for a wide range of applications. The Multifunctional Power Supply is conducted with the help of the low-voltage DC+AC power source supplying DC current with superimposed alternating current. These processes conduct hard anodizing at a very low DC voltage (12-18 volts-average) providing superior coating of anodic oxide. Moreover, alloys with a very high concentration of copper, such as 2011, are easily anodized within short periods of time without burning. The 6061 alloy with specific heat treatment T-6 may be anodized up to thickness of 5-6-7 mils, whereas the DC high-voltage process could only provide thickness not exceeding 2.5-3 mils on the same alloy. A higher copper content alloy such as 2024 can be anodized with the help of low-voltage process up to 6 mils thickness. Power supply is intended to be used for any anodizing processes from conventional anodizing, type II to hard anodizing.

New Nickel-Free Cold Seal
Fabio Vincenzi, Italtecno;
Walter Dalla Barba, Italtecno*

Having an understanding of the different sealing processes available today on the market (nickel-based cold seal, mid temperature seal and hot seal), this presentation will explore a new, ecological, nickel-free cold sealing method. In fact, nickel is a heavy metal with toxic properties and should be banned in many countries of the world in a few years.

The research was performed utilizing the following sealing process:

  • Nickel-free cold sealing 80 to 90 ºF
  • Tap water rinsing
  • Hot ageing step 180 to 190 ºF

Research data comparing the new Nickel-Free Cold Sealing Process and standard conventional sealing processes will be presented. The data will prove that nickel-free cold sealing is absolutely possible and will produce sealing quality that is according to, and in some cases greatly exceeds, general aluminum industry standards and the seal quality of commonly used seal products on the market today.

Correlating Hardness and Wear Resistance on Hard Anodized Aluminum
Jan Siden, Bodycote Ytbehandling AB

Type III anodizing is known for its hardness, as well as its wear resistance. Industry standards used to measure hardness may be believed (mistakenly) to indicate wear resistance, too. But these two properties are not the same. The current work reflects ongoing investigations
comparing hardness and wear resistance of hard-anodized aluminum produced under different parameters using different alloys. Results of experiments performed thusfar indicate that it may be misleading to assume that a direct correlation exists between these properties. Available data will be presented. The consequences of focusing simply and solely on the hardness will also be discussed.

Electropolish/Anodize Process Procedures for type II – III – 23
Anodize Including the latest Advanced Constant Current Density Programs for all Aluminum Alloys
Fred Schaedel, Alpha Process

A new Electropolish Activated Type II – III Anodize Process also provides excellent passivation. The latest advanced Constant Current Density (CCD) programs including slow pulse – step – ramp graphs to CCD levels and dwell periods for all aerospace, military, and commercial alloy specifications will be presented. Data logger graphs from various facilities indicate energy savings for specific anodize production loads.

Focus Session 2: Technology Forum

Acid Etch Update
Linda Newman, Houghton Metal Finishing

Since the recent introduction of a new acid etch process to the anodizing industry much new information has been discovered. With many anodizers switching from caustic etch to acid etch, additional questions have arisen. What are the new discoveries of the acid etch process? What are the advantages and disadvantages of both processes? Latest technical updates will be presented.

Alkaline Anodizing
Enzo Strazzi, Italfinish SpA
Chiara Ferrari, Italfinish SpA
Sabrina Ferri, Italfinish SpA
Onita Crisan-Sintoma, AnodAM*

Everybody is familiar with a sulfuric-acid-based solution when aluminum (and in some cases, titanium) are anodized, but just a few technicians know what happens when an alkaline solution is used. A wide range of amazing options is opened if a proper nontoxic alkaline solution is used with a suitable machine and correct procedure. High-silicon cast aluminum become white and aesthetic and suitable to be used standalone or as a base for high corrosion-resistant powder coating. Any type of magnesium alloy cast or extruded material finds its "natural" and best finishing. Titanium and its family members become pastel colored. Furthermore, if somebody likes black matte tones, a simple modification of the solutions produces aesthetically and technically valuable finishing with opportunities for innovative applications. Practical experiences from industrial plants and wide bibliography will be mentioned.

Advances in the Dyeing of Anodized Aluminum
Pinakin Patel, Techevon LLC

This presentation will review new developments in dyeing anodized aluminum. Newer technologies of manufacturing allow for dyes to be developed with very high light fastness and with purity that was not previously available. Furthermore, black shades can be produced with different undertones depending on the needs of the customer. The presentation will also introduce a new line of dyes that can be sealed using the popular cold sealing methods of today with minimum-to-no bleeding. Additionally, the presentation will cover details of the properties of various dyes along with light fastness and contamination effect studies of various dyes. Some of these products are new molecules made exclusively for use on anodized aluminum.

New OEM Marketing Approach to Promote the Use of Anodized Aluminum
Mark Self and Markus Kleinert, Clariant Corporation

OEMs that outsource their aluminum finishing overseas, while maintaining design and engineering functions onshore, are encountering finish quality and reproducibility problems. Clariant has responded with a centralized OEM support platform, establishing a new product and technology development lab, and partnering with regional distributors. This presentation describes the new business model and focuses on recent product and technology developments in "Green" chemistry, novel colorants, and durable polysilazane coatings for anti-graffiti applications.

Focus Session 3: Scientific

Thin Film Anodizing – Novel Structures & Applications
Mark Jozefowicz, Reliant Aluminum Products LLC

It is well known that the structure of an anodized aluminum coating is related to the process conditions used to create it. To be able to develop new and interesting materials by simply varying electro-chemical parameters while anodizing has intrigued scientists for decades. The Anopore™ membrane is a market successful application which grew out of such a development. Low cost thin film coatings with unique structures can also be created by anodizing aluminum and applied in unusual ways. When combined with chemical metallization to produce vibrant interference colors, an entirely new set of applications are attainable. A discussion on electro-chemical techniques used to create such materials and their application will take place. Prototype examples that have been created on a continuous anodize line will be on display.

New Uses for Anodized Aluminum Oxide (AAO)
H. Hau Wang, Argonne National Laboratory

Anodized aluminum oxide (AAO) has attracted significant interest among the nano-science and engineering research community in recent years. AAO consists of highly aligned nanopores “self-assembled” in a hexagonally close-packed pattern. The pore diameter and pore-to-pore distance range between ~10 to 300 nm and 30 to sub-micron, respectively. These nanopores are highly ordered within a domain but do not exhibit intrinsic long-range order. These nanopores can be filled with use of electro-deposition to prepare metallic (Cu, Ag, Au, etc.) or ferromagnetic nanowires (Fe, Co, Ni, etc.). These nanoscaled objects have been studied for their magnetic anisotropic behavior in the laboratory. Complex multi-segmented nanowires have also been developed. The multi-segmented design may be used to enhance self-assembly of these materials. Together with chemical vapor deposition (CVD) and atomic layer deposition (ALD), semiconductive nanowires and nanotubes such as ZnO, CdS, CdSe, GaAs, etc., have been synthesized for photonic devices, transistors, and biological sensing and detection applications. The AAO membrane when coated through ALD technique has been developed into a new membrane catalyst. With precise reaction parameter control, chemical reaction such as dehydrogenation with high selectivity has been demonstrated.

The AAO membrane when coated with ZnO was reported to be a high surface area dye-sensitized solar cell with reasonable power efficiency. With short anodization time, a nanowell structure can be prepared with shallow nanopores. These nanowells have been developed into hydrogen sensors with Pd nanoparticle decoration.

In addition, these nanowells give rise to interference colors and the interference spectra are sensitive enough to pick up one monolayer of explosive molecules such as di- and tri-nitrotoluene. Due to the high aspect ratio (>1,000) in the AAO nanopores, the AAO membranes are reported to lead to highly anisotropic etching and are being developed into various MEMS (micro-electromechanical system) devices such as RF MEMS inductor, microcantilevers, capacitive MEMS humidity sensor, and various gas sensors, etc. The frame work of AAO is very similar to the micro-channel plate (MCP) used in various devices such as night vision goggles and photodetector, etc. It is possible that AAO with proper surface coating may lead to inexpensive large area detector. This presentation will briefly review AAO based research efforts from basic research to energy and security applications.

A Point Defect Interpretation of the Stability of Anodized Aluminum in
Chloride-Containing Media
Digby Macdonald, Penn State University

All reactive metals that are used for structural, electronic, or decorative purposes, such as aluminum, chromium, nickel, iron, zirconium, magnesium, and many others, and the alloys of these elements, owe their kinetic stabilities to the formation and continued existence of a “passive” oxide film on the surface that effectively separates the reactive metal from the corrosive environment. This film was initially detected by Michael Faraday in 1833 as the result of his famous “iron in nitric acid” experiment. Since that time, numerous models have been devised to describe the properties of the passive film, which commonly forms as a bi-layer structure comprising a point-defective barrier layer and a porous, precipitated outer layer. In the case of aluminum and its alloys, the barrier layer, which grows directly from the metal, has a general formula of Al2+xO3-y, where x and y describe the non-stoichiometry of the phase, with y > 0 for an oxygen-deficient phase, due to the existence of oxygen vacancies, and x > 0 for a metal-rich phase due to the existence of cation interstitials. These two defects dope the barrier layer n-type in electronic character. If x < 0, corresponding to a cation-deficient phase, due to the existence of vacancies on the metal sub-lattice, the oxide is doped p-type in electronic character and hence the electronic properties of the barrier layer can be used to ascertain the dominant defect in the system.

On the other hand, the outer layer forms via the hydrolysis of Al3+ cations that are ejected from the barrier layer and the subsequent precipitation of AlOOH or Al2O3, often in the form of a film that contains pores normal to the surface in a roughly hexagonal array. The outer layer commonly contains species from the solution (e.g., borate) that are co-precipitated with the oxyhydroxide or oxide phase. These species are never found to be present in the barrier layer, whereas alloying elements present in the substrate metal are generally found in both the barrier and outer layers. These observations are consistent with the origins of the barrier and outer layers being direct growth from the metal and precipitation, respectively. The present talk will review what is known about the passive film that forms on aluminum under anodizing conditions and will show that the formation and breakdown of the film is well-described by the Point Defect Model (PDM) that has been developed by the author over the past three decades. The PDM also identifies strategies for producing more corrosion-resistant surfaces via chemical or physical modification of the outer layer. Some of these strategies are already practiced in the anodizing industry (e.g., sealing, chromate conversion coatings), but others are less-well developed. Modification of the barrier layer in terms of interaction of mobile point defects (e.g., cation vacancies) with immobile foreign cations on the cation sublattice is also an attractive strategy, particularly for improving pitting resistance, but it has not been explored in a comprehensive manner.

Electrochemical Kinetics, Transport and Pattern Formation in Anodizing
Dale Barkey, University of New Hampshire

The formation of anodic oxide finish is examined as a far-from-equilibrium electrochemical phase-formation process. In this view, the growth of a highly ordered oxide phase is related to competition among electrostatic and diffusive driving forces, surface kinetics, and spare charges. The framework is compared with published models of oxide growth as well as experimental data from this laboratory.

* indicates presenter

The views expressed and the information, materials, processes and techniques described in the papers and presentations planned for inclusion in the Conference program represent the views and developments of the individual authors and/or the companies or organizations indicated. The Aluminum Anodizers Council (the “Organizer”) makes no representations as to the accuracy or sufficiency of any of the information set forth in the individual papers. The Organizer does not necessarily endorse or approve the views expressed in any of the papers. The Organizer and the individual authors/companies/organizations presenting papers assume no responsibility or liability for the use of any information, materials, processes or techniques described. The Organizer and the individual authors/companies/organizations hereby disclaim any warranties, expressed or implied, in connection with any information included in the presentations made during the Conference or in the papers published in the Proceedings.
The Council reserves the right to alter the program and/or schedule at its sole discretion.