|2010 Anodizing Conference Abstracts|
Abstracts for the 2010 Anodizing Conference were organized by General Sessions and the following Focus Sessions: Trachnical, Environmental and Scentific.
Roadmap to Aerospace Anodizing
Warren J. Fullen, Boeing
Gary Kriesch, Walgren Company
Earl Turns, Earl W. Turns & Associates
The aerospace industry can be an attractive market segment for aluminum anodizers, but the successful anodizer needs to understand how to avoid supposed barriers to entry. Presented will be insightful advice as to how to approach a manufacturer’s offload procurement buyer, as well as how to become prequalified under third-party arrangements (e.g., NADCAP). A clear understanding of the types of anodizing called for by aerospace entities, in light of essential performance characteristics, is fundamental to the process.
The Effect of Anodic Hot AC Pretreatments on the Anodization of Aluminum
Neslihan Alpay, Istanbul Technical University
Mustafa Ürgen, Istanbul Technical University
6016, 6063, 1050 and pure aluminium alloys are exposed to various pretreatment processes prior to direct current (DC) sulphuric acid (H2SO4) anodization. DC anodization processes require pretreatments due to the cleaning of the surface of the samples. A generally used pretreatment method, which is etching in sodium hydroxide (NaOH) and then polishing in nitric acid (HNO3) is taken as a reference process. Two other newly developing methods, which are alternative current (AC) hot sulphuric acid anodization and alternative current hot phosphoric acid (H3PO4) anodization are implemented on Al samples as pretreatment processes prior to DC anodization. Using hot AC anodising as a pretreatment step required shorter pretreatment durations down to 15 seconds while the reference pretreatment process endured more than 60 seconds. Parameters for these processes are evaluated. After the anodization step, hot AC sulphuric acid anodization pretreated surfaces showed similar pore structures compared to the surfaces treated with reference pretreatment process, while the hot AC phosphoric acid anodization pretreated surfaces had larger pore diameters. Scanning electron microscope (SEM) and energy dispersive X-ray spectrometry (EDS) analysis are performed to compare the surface structures of the pretreated and anodized Aluminum samples.
FTC Guidelines on Green Marketing Claims
Charles Simmons, Law Offices of Charles T. Simmons, LLC
In marketing, everyone wants to say good things about their product. Emphasis on environmental benefits receives special attention in today's business climate. "Sustainable," "low-carbon," "carbon neutral," "eco-friendly" and "recyclable" are among the many "Green Marketing" claims heard today. The Federal Trade Commission (FTC), through recent testimony to Congress and law enforcement actions (K-Mart, Dyna-E and Tender Corp.) has clearly demonstrated it will vigorously pursue green marketing claims it considers unsubstantiated or false and misleading. This discussion focuses on the evolving regulatory framework of environmental marketing, and how to distinguish permissible claims from "Greenwashing" that risks FTC enforcement or action by aggrieved competitors. Also to be discussed, are emerging legislative and regulatory initiatives that could presage a dramatic shift in the way chemicals are regulated in the U.S. Legislation before Congress and EPA regulatory initiatives, if unchecked, foreshadow a trend towards the "Precautionary Principle" and a European REACH-style chemical regulatory regime.
Anodizing Quality Aluminum Sheet Material with High Recycled Content
Greg Courval, Novelis Global Technology Center
Increased environmental awareness and LEED requirements have led to strong interest in maximizing the amount of recycled content in anodizing quality (AQ) aluminum. Although other aluminum sheet products incorporate a substantial level of recycled content, the stringent quality targets required to meet consistency in appearance for AQ material could only be met until now by starting with smelter quality ingot. To maintain the high level of finish and incorporate high levels of recycled aluminum, a novel clad aluminum alloy package has been developed. This material is composed of a 3XXX series alloy core material produced largely from recycled aluminum clad with AA5005 smelter grade alloy so that the overall recycled content is 70 percent or greater. The fabrication process and material properties are discussed in this presentation. Additionally, the etching and anodizing response along with color and gloss properties are then compared to conventional AQ sheet with conclusions covering other AQ clad alloys.
Connecting Theory to Practice: The Science of Successfully Anodizing Die Cast Substrates
Jude Mary Runge, Compcote International
Larry Chesterfield, Anodizing Technologies, Inc.
Die castings pose some of the most challenging problems in anodizing. The finish can be too thin, non-uniform and/or have an unfavorable appearance. These are common problems with a variety of practical solutions; they are easy to recognize, but the source(s) for the problem(s) remain(s) unknown and recommended solutions may or may not work. Critical to solving the problems of anodizing die castings is understanding the die cast substrate and the impact of alloy composition, casting quality and microstructure, as well as surface condition. These substrate quality issues are just as important, maybe more so, than anodizing conditions and technique. Through the use of actual case studies that provide real-life solutions in terms of anodizing theory and interfacial science, this presentation provides some explanations by tying together metal finishing practice with anodizing science.
U.S. Fair Trade Committee Update
Steve Jones, King & Spalding
Steve Jones, attorney for the U.S. Aluminum Extrusions Fair Trade Committee—a coalition of domestic manufacturers of aluminum extrusions—will brief the audience on the latest news regarding the China Imports Petition filed with the U.S. Department of Commerce and the U.S. International Trade Commission. These developments follow a similar trade case successfully brought by Canadian extruders.
On August 31, 2010 the U.S. Department of Commerce (“Commerce”) announced its affirmative, preliminary determination in the countervailing duty investigation of aluminum extrusions from China. Commerce has determined that imports from China are benefiting from various subsidies that are countervailable under the law, which means that countervailing duties may be applied to imports to offset these subsidies and remedy the unfair trade. In addition, Commerce is investigating whether imports are being sold at prices that are less than fair value (i.e., dumped) in a separate investigation. The deadline for the preliminary determination in the antidumping investigation is October 27, 2010.
The Fair Trade Committee is an independent coalition whose supporters account for approximately 80 percent of production in the U.S. aluminum extrusions industry. More information about the case is available online.
Lean Practices in the Metal Finishing Industry
William Corcoran, LightMetals Industries
All anodizers can use lean practices to work smarter and be more profitable without a large capital investment. The objective is to work to identify and eliminate wasteful practices and focus on value creation by working smarter and preserving value with less work. The essence, therefore, is to achieve maximum efficiency by identifying and evaluating production processes. The investment is in, and
with, the people that work in the shop; identifying bottlenecks, inefficient flow, lack of resources, and steps that do not have value to the customer.
Lynn Brown, Hydro Aluminum
The latest intelligence on key global aluminum market trends will be presented through an assessment of recent/current conditions and an outlook for various market sectors. Included will be an analysis of the impact the economy has had on the extrusion industry, prospects for recovery, and implications for the anodizing industry.
Focus Session 1: Technical Track
Process Controls, Documentation and Verification
Kevin Bodily, METALAST
There are various levels of process control that can be implemented in any process line. These systems can range from simple stand-alone controllers that maintain a single process variable to complex programmable logic control (PLC) systems that run automatic process lines. Whatever the degree of complexity, however, the control system must provide a minimum amount of functionality to achieve adequate results. This naturally raises the question, how much complexity does a process line require to achieve desired goals? Is controlling process parameters enough, or should the system also document the process for future verification? How do budgetary constraints affect the complexity of the system? Is the system flexible, expandable? How much maintenance is required? These are some of the questions that will be addressed and answered.
Innovative, Ecological and Low-Cost Matte Finish
Fabio Vincenzi, Italtecno Srl
Nowadays in the aluminum anodizing industry it is ever more important to obtain new finishes through technologically advanced equipment and plants, as well as through innovative, green-friendly and economical chemical processes. The desired finishing is obtained by means of specifically designed brushing and polishing machines and, when possible, automatic anodizing plants for better control of process parameters. The finishing is then completed by one or more chemical process. An interesting and innovative chemical technology, not yet very well known in the market, is a new type of alkaline etching, specifically formulated to give a matte finish in about half the time compared to traditional alkaline processes, and with a large reduction of caustic soda consumption and a major reduction of dissolved aluminum. From these considerations we can deduce how innovative, ecologically friendly, and “low cost” this process can be.
Replacement for the Chromic/Phosphoric Acid (CPA) Test for Sealing Quality
Joakin Oxelbark, Sapa Technologies
The sealing quality test specified by Qualanod is the Chromic/Phosphoric Acid (CPA) weight-loss test as described in EN 12373-7. This involves the use of chromic acid, which has carcinogenic and allergenic properties. Restrictions for the use of this chemical are anticipated in the near future so it is considered important to identify an alternative. The aim with this work was to investigate some candidates for replacement of the chromic/phosphoric acid test. Four sealing methods were used, because the weight loss is likely to depend on the kind of sealing method used.
Sealing was made following the recommended working conditions in production given from the chemical supplier but also with a deviation in pH of sealing solution, sealing time, and sealing bath temperature. Samples were also taken from production plants using the four relevant sealing methods. Complementary dye spot and admittance measurements were made. The response in the different weight-loss tests was very different depending on sealing method and will be explored in this presentation.
Anodizing Difficult Alloys
Fred Schaedel, Anodic Technical Services
Numerous Pulse - Step - Ramp Procedures have been developed, modified and improved over the past 50 years with the help of experienced anodizers right on the anodizing line. The most efficient, energy saving and problem solving of these procedures for Type II, 23 and III hard anodize will be presented. Special ramp and run procedures will cover those problem alloys designated as difficult due to burning and quality issues. These procedures will benefit all alloys but there will be special emphasis placed on 2011, 2024, 2219, 5083, 7050, 7075, 7178 and castings including 380 and other high-silicon alloys. Data logger graphs collected and revised over the past 30 years will be presented, which prove time and energy savings of more than 50 percent without burning or powdering of all aluminum alloys (1000 – 8000 Series) for commercial aircraft and military applications.
Aerospace Anodizing Processes
Warren J. Fullen, Boeing
Gary Kriesch, Walgren Company
Earl Turns, Earl W. Turns & Associates
A number of specialized anodizing processes, including chromic acid anodizing (CAA), phosphoric acid anodizing (PAA), boric-sulfuric acid anodizing (BSAA), and thin-film anodizing, while common to the aerospace sector, are seldom practiced elsewhere. Each method has distinct specification requirements that stipulate controls for facility, process, and chemical constituents; this session provides a valuable introduction to such requirements.
Focus Session 2: Environmental Track
Integrate Cleaning with the Processing of Aluminum and the Environment
Richard Mahn, Houghton Metal Finishing Company
The process of cleaning removes unwanted materials from “something,” which for this presentation is aluminum. The challenge of cleaning is that this chemical process must be done in a manner that completely removes the undesirable material without having a negative impact on that which is being cleaned. However, there must of necessity also be consideration given to the impact cleaning has on the environment. Once we have removed the unwanted materials, what do we do with them? What about the cleaners themselves? The purpose of this presentation is to present some cleaning basics and then to discuss the evolution of the cleaning process as it relates to the environment.
Non-Chromium Seals for Clear and Hard Anodized Aluminum
Alp Manavbasi, METALAST
Anodized aluminum alloys are required to be sealed for the optimum corrosion resistance. Chemical reaction products formed during the sealing process fill the pores and make the anodized layer stable under a wide range of corrosive atmospheric and environmental conditions. Hexavalent-chromium-based sealers are commonly used for sealing the Type II Sulfuric Acid Anodized and Type IIB Thin Film Sulfuric Acid Anodized aluminum alloys. However, strict environmental regulations, tight waste disposal standards, and very low personal exposure limits (PEL), which are set by OSHA, have made the application of hexavalent-chromium-based seals prohibitively expensive. This presentation will describe a newly developed nonchromium process for sealing anodized aluminum, which has proven to be very effective with outstanding performance on anodic coatings. Corrosion characteristics of the anodized and sealed aluminum were investigated using Electrochemical Impedance spectroscopy (EIS) and Neutral Salt Fog (NSF) techniques.
Steps to an Environmentally More Sustainable Business Model
Michael Ritzenhoff, Seidel
As aluminum’s recyclability supports efforts toward sustainability, anodizing companies also should emphasize sustainability by implementing appropriate procedures and equipment. Financial rewards are seen to support the environmental benefits. The present work reflects efforts of one anodizing company to improve processes such as degreasing, brightening, sealing, rinsing, and heat recovery, to name just a few. Equipment upgrades range from more efficient boiler chillers, and power factor correction, to racking, transformers, and reverse-osmosis apparatus. Further themes include acid recycling, cogeneration, more aggressive water recycling, new wastewater treatment technologies, and general reduction of waste. Audience discussion of ideas will be encouraged.
Regulatory Initiatives Impacting Surface Finishing Operations
Jeff Hannapel, The Policy Group
This presentation will focus on recent regulatory developments impacting surface finishing operations, including challenges facing the use of hexavalent chromium and long-chain perfluorinated fume suppressants, nickel supply issues, controls for greenhouse gas emissions, and new legislation and regulatory developments for chemical use. In addition, the presentation will also address the emerging trends in regulating industrial processes, chemicals, raw materials, and products containing hazardous substances.
Environmental Regulations in Ontario
Ross Borthwick, Premier Environmental Services Inc.
The manufacturing sector in Canada is subject to environmental regulation undertaken by all levels of government – federal, provincial/territorial, and municipal. The federal and provincial governments in Canada both have jurisdiction over environmental matters and their environmental statutes often overlap. In addition, municipal governments are traditionally responsible for water and sewage systems and noise issues. The presentation will provide a general overview and update of the current environmental regulations affecting the manufacturing sector in Ontario. It should be noted that Ontario has the largest manufacturing sector in Canada and is a good starting point for the discussion of regulations in Canada. Topics will include air emissions, wastewater and stormwater, solid waste, hazardous building materials and storage.
Focus Session 3: Scientific Track
Nanoporous Anodic Aluminum Oxide Templates for Nanowire Arrays
Bethanie Hills Stadler, Ph.D., University of Minnesota
Due to its nanoporous structure, anodized aluminum oxide (AAO) is an excellent template for metallic nanostructures that are useful in various magnetic, photonic, electronic, and biological applications. Other popular nano-templates will be briefly discussed and compared to AAO, including block co-polymers and ion-track etched polymers. AAO contains columnar nanopores with diameters of 5-500nm with aspect ratios of 1-104. Ordered pores can be obtained using either 2-step anodization or nano-imprinting of the initial Al metal prior to anodization. Both ordered and non-ordered AAO can be easily integrated with Si. A variety of shapes are also possible, including Y-junctions, antennae, and tree structures. Once the templates are fabricated, the most efficient method of obtaining nanowires is electrochemical deposition of a metal inside the columnar pores. The resulting nanowires can be used for magnetic artificial cilia arrays in biological sensors and actuators. These cilia have resonant frequencies ranging from Hz to GHz depending on their diameters and lengths. Arrays of nanowires also have great potential for high density memory applications, including static applications like hard-drive media and dynamic applications such as heads and random access memory (RAM) with almost 2 Terrabits per-square-inch densities. A third application of nanowires arrays is bio-plasmonic sensors where the photonic resonance of Au nanowires can be controlled using shape. In summary, anodic alumina is an exciting material for the growing field of nanotechnology with a wide range of applications possible.
Anodized Aluminum Oxide Based Large Area Photo-Detectors
Seon Woo Lee, Ph.D., Argonne National Laboratory, Materials Science Division
There is a long-existing interest to develop a large-area, inexpensive and fast-response radiation detector. Current photo-detector technology, based on photo-multiplier tube (PMT) is expensive and not easy to scale up. The multi-channel plate (MCP) design uses optical fibers in a hexagonally close-packed array, rendering each optical fiber functioning like a PMT. These optical fibers are made of lead silicate glass. The MCP was made by optical fiber drawing, slicing, and chemically etching to create hollow fiber cores. The lead doped silicate glass has high secondary electron emission coefficient and therefore behaves like a miniaturized PMT. The optical fiber diameter ranges from 40 to ~2 microns. As the fiber diameter decreases, fabrication is becomes more difficult. At present, the state-of-the-art commercially available MCP has pore diameter around 2 microns. In addition to its expensive cost, the mechanical strength also poses a concern for its application. Smaller pores are expected to enhance temporal and spatial resolution. We have taken a new approach: instead of using silicate (SiOx)-based MCPs, we are developing porous alumina (Al2O3) or anodized aluminum oxide (AAO) based MCPs. AAO has several intrinsic advantages. Due to its internal vertically aligned nanopores, the AAO can be etched to create a nearly vertical edge. Aspect ratio of the pores (length/diameter) can be well controlled. The intrinsic nanopore diameter from 20-300 nm also allows MCP pores to be much smaller than the current 2 microns. However, to prepare AAO pores with diameter from 300 nm to ~1,000 nm, direct anodization does not work well. We applied laser writer patterning/photolithography to prepare patterned large pores with diameter from 40 to 4 microns. We plan to prepare pyramidal shaped tip arrays through e-beam lithography. Combined nanoimprint and anodization allows us to develop a new strategy to prepare pore-to-pore distance anywhere between 300 nm to 2 microns and beyond. Therefore, a wide range of AAO- based MCP devices can be fabricated considering hierarchical AAO intrinsic nanopores and lithography-assisted patterning together with anodization. The AAO is inexpensive and large-scale applications are possible. These new results will be presented.
Formation of Al-based Nanostructured Thin Coatings on Aluminum Substrates using a Micro-arc Deposition Technique
Mathieu Brochu, Ph.D., McGill University
Nanostructured materials are known to exhibit superior properties due to their refined grain size, and have a promising future for severe applications. Unfortunately, the cost associated with the fabrication of this technology is often the major drawback for their utilization as a bulk material. Electrospark deposition is a low-cost micro-arc welding process that can achieve cooling rates approaching 105-106°C/sec, allowing for solidification of nanostructure. Consequently, a low-cost nanostructured coating can be deposited on virtually any conductive substrate material, taking advantage of the properties provided by nanometric grains without compromising the manufacturing cost of components. This presentation will demonstrate the feasibility of engineering the surface of bulk Al components with various nanostructured Al alloy deposits, including Al-Si, Al-Ni and Al-Mg alloys. Results on the solidification microstructure and mechanical properties, such as dynamic hardness and impact fatigue, will be presented.
Prediction of the Accumulation of Pitting Damage on
Aluminum in Aqueous Solutions
Digby Macdonald, Center for Electrochemical Science and Technology,
Department of Materials Science and Engineering,
Pennsylvania State University
Aluminum and its alloys are used extensively as structural materials in applications ranging from domestic housing (siding and roofing), beverage containers, aircraft, and boats and ships, just to name but a few. In all of these applications, corrosion is a major issue, because corrosion results in degradation of the properties that make aluminum and its alloys attractive for these applications (e.g., high strength-to- weight ratio). Aluminum and its alloys suffer virtually all forms of corrosion, including general corrosion and different forms of localized corrosion. The latter include pitting corrosion, crevice corrosion, galvanic attack, filiform corrosion, stress corrosion cracking, corrosion fatigue, and hydrogen embrittlement. Despite this plethora of degradation mechanisms, aluminum and its alloys are surprisingly durable in service and can provide many years of trouble-free service. This resistance to corrosion can be attributed to anodization, which is the process of forming and sealing a thick oxide film on the surface by electrochemical polarization, to form an impervious barrier between the reactive metal and the corrosive environment. Actually, the anodic oxide film forms as a bi-layer comprising a thin defective barrier layer (typically a few nano-meters thick) that grows directly into the metal and a thick layer (typically a fraction of l micron thick) and which contains species present in the solution at the time of formation (e.g., borate ion when formed in borate buffer solution). This porous outer layer forms via precipitation of AlOOH or Al2O3 (depending upon the anodizing conditions) from Al3+ ions that are transmitted through the barrier layer. The pores are readily sealed by boiling the anodized component in water, which causes dissolution followed by re-precipitation of the outer layer material into the outer layer pores, thereby enhancing the corrosion resistance. Alternatively, oxidizing inhibitors that promote the oxidative repair of the anodic oxide film if ruptured have also been extensively used, particularly in the aircraft industry in the form of chromate conversion coatings. However, chromate is now banned, because of the carcinogenic properties of Cr(VI) and an alternative is now being actively sought.
As with any systems that are fabricated from reactive metals, those manufactured from aluminum are subjected to corrosive degradation that impairs performance and service life. This problem could be effectively managed if methods were available for predicting the rate of accumulation of damage due to corrosion, particularly that due to localized corrosion, such as pitting. Thus, such a tool would allow effective scheduling of maintenance during scheduled outages of the system, the cost of which has been built into the price of the product. Avoidance of unscheduled outages for servicing and repair should provide an enormous incentive for the development of the required technology. We have argued strongly that effective predictions of damage can only be done deterministically, using models whose outputs (predictions) are constrained by the natural laws. These models are discussed in this presentation.
Metallurgical Assessment of Acid Etch as Anodizing Pretreatment
Nick Parson, Rio Tinto Alcan
A number of anodizing lines in the U.S. and Australia have adopted alternative anodizing pretreatments using fluoride-based etch solutions. The claimed benefits include shorter cycle times and freedom from streaking. The traditional caustic-based etchants are known to be sensitive to the alloy chemistry and microstructure giving rise to the well-known color or shade match problem. This presentation describes a test program conducted to measure the response of the acid etch process to various alloy compositions. The profiles tested included some with deliberately produced extrusion streaks. The impact of acid etch and combined caustic etch times was assessed along with the surface topography produced by these treatments. Comparisons were also made on the same profiles when treated with conventional caustic etching. Significant differences were found between acid etch and caustic etching in terms of the sensitivity of the final finish to alloy composition and also the ability to hide extrusion streaks.
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.