The document summarizes chromium-free pre-treatment processes for aluminium as alternatives to chromate conversion coatings. It describes several processes including those based on molybdate, permanganate, phosphate, and titanium/zirconium, as well as cerium-based processes, silane treatments, and anodizing. Each process is outlined briefly, noting advantages such as corrosion protection and adhesion, as well as limitations regarding color, thickness, or variability in performance between alloy types. Health, environmental and regulatory concerns with chromate and other hazardous chemicals like hydrofluoric acid are also summarized.
This is a ppt. on protection from corrosion of steel reinforcement in concrete structures. I had prepared this as a part of my class seminar. I made this by referring to the books on Concrete Technology by M.S.Shetty and M.L.Gambhir
surface characteristics and electrochemical impedance investigation of spark-...mohammad fazel
In this study, the surface characteristic of oxide films on Ti-6Al-4V alloy formed by an anodic oxidation treatment at potentials higher than the breakdown voltage was evaluated.
An introductory presentation on corrosion and its prevention. Importance of corrosion, cost of corrosion, various forms of corrosion, and preventive methods are given.
Corrosion of Metals and Prevention of CorrosionHiba Hibs
about corrosion of metals like copper , iron , silver with diagrams and also methods to prevent corrosion like alloying , chrome plating , galvanization etc.
This lecture describes the key factors associated with conversion coatings on aluminium can be appreciated, such as general and local behaviour of the aluminium surface, range of conversion coatings and interrelationships, requirements of conversion coating, tailor-making of coatings, current and future issues. Some familiarity with the subject matter covered in TALAT This lectures 5101, 5102, 5201 is assumed.
Acid Corrosion Inhibitor is designed specifically to inhibit the acidic attack on various metals such as Brass, Copper, Tin, Nickel, Zinc, Lead, Galvanized surface and all other type of steel.
This is a ppt. on protection from corrosion of steel reinforcement in concrete structures. I had prepared this as a part of my class seminar. I made this by referring to the books on Concrete Technology by M.S.Shetty and M.L.Gambhir
surface characteristics and electrochemical impedance investigation of spark-...mohammad fazel
In this study, the surface characteristic of oxide films on Ti-6Al-4V alloy formed by an anodic oxidation treatment at potentials higher than the breakdown voltage was evaluated.
An introductory presentation on corrosion and its prevention. Importance of corrosion, cost of corrosion, various forms of corrosion, and preventive methods are given.
Corrosion of Metals and Prevention of CorrosionHiba Hibs
about corrosion of metals like copper , iron , silver with diagrams and also methods to prevent corrosion like alloying , chrome plating , galvanization etc.
This lecture describes the key factors associated with conversion coatings on aluminium can be appreciated, such as general and local behaviour of the aluminium surface, range of conversion coatings and interrelationships, requirements of conversion coating, tailor-making of coatings, current and future issues. Some familiarity with the subject matter covered in TALAT This lectures 5101, 5102, 5201 is assumed.
Acid Corrosion Inhibitor is designed specifically to inhibit the acidic attack on various metals such as Brass, Copper, Tin, Nickel, Zinc, Lead, Galvanized surface and all other type of steel.
Chromium is a metal that exists in several oxidation
• Chromium is a metal that exists in several oxidation or valence states, ranging from chromium (-II) to chromium (+VI).
• Chromium compounds are very stable in the trivalent state and occur naturally in this state in ores such as ferrochromite, or chromite ore.
• Chrome III is an essential nutrient for maintaining blood glucose levels
• The hexavalent, Cr(VI) or chromate, is the second most stable state. It rarely occurs naturally.
40 cfr 261.4(b)(6) The RCRA Exclusion From Hazardous Waste for Trivalent Chro...Daniels Training Services
The Trivalent Chromium Wastes Exclusion from Regulation as a Hazardous Waste
40 CFR 261.4(b)(6) excludes Trivalent Chromium Waste, a solid waste, from regulation as a hazardous waste if the requirements of the regulations are met. This presentation briefly summarizes the requirements of this RCRA exclusion from regulation.
Those in the leather tanning industry, leather product manufacturing industry, shoe manufacturing industry, and titanium dioxide manufacturing industry should be aware of this RCRA exclusion and its possible impact on their operations.
10 major industrial applications of sulfuric acidrita martin
sulfuric acid commonly known as king of chemicals and also as oil of vitriol find its applications across many industries like lubricants, drugs, rayon, metal processing, batteries, chemical manufacturing and more
A SHORT REVIEW ON ALUMINIUM ANODIZING: AN ECO-FRIENDLY METAL FINISHING PROCESSJournal For Research
Protection of aluminium alloys is most commonly done by forming anodic films. Anodic films can also be formed on metals like titanium, zinc, magnesium, niobium, and tantalum. Aluminium alloy parts are anodized to greatly increase the thickness of the natural oxide layer for corrosion resistance. A thin aluminium oxide film, that seals the aluminium from further oxidation when it is exposed to air. The anodizing process increases the thickness of the oxidized surface. Anodizing is accomplished by immersing the aluminium into an acid electrolyte bath and passing an electric current through the medium. In an anodizing cell, the aluminium work piece is made the anode by connecting it to the positive terminal of a dc power supply and the cathode is connected to the negative terminal of the dc source. Sealing is needed to seal the pores in oxide layer to prevent further corrosion. Oxide layer on the anodized aluminium has a highly ordered, porous structure that allows for secondary processes such as dyeing, printing and sealing. Nanowires and nanotubes can be made by using the pores in the oxide layer as templates.
A presentation giving the basic principles of corrosion. Electrochemical nature of corrosion, anodic and cathodic reactions, electrode potentials, mixed potential theory and kinetics of corrosion, thermodynamics of corrosion and Pourbaix diagrams, and passivization behavior of metals are outlined.
Protection des métaux contre la corrosionCHTAOU Karim
Cette présentation présentent tout d’abord les principaux types de la corrosion et il présente une description détaillée des trois grandes méthodes, préventives et curatives, utilisées en anticorrosion.
This lecture describes the process of anodic oxidation of aluminium, which is one of the most unique and commonly used surface treatment techniques for aluminium; it illustrates the weathering behaviour of anodized surfaces. Some familiarity with the subject matter covered in TALAT This lectures 5101- 5104 is assumed.
Anti arthritic-efficacy-and-safety-of-crominex-3+(trivalent-chromium-phyllant...Annex Publishers
Abstract
The present investigation was undertaken to evaluate the therapeutic efficacy and safety of Crominex® 3+ (a complex of trivalent chromium, Phyllanthus emblica (Amla) extract and purified Shilajit) in moderately arthritic dogs. Eleven client-owned moderately arthritic dogs in a randomized double-blinded study received placebo or Crominex® 3+ twice daily for a period of 150 days. On a monthly basis, each dog was evaluated for arthritis associated pain (overall pain, pain upon limb manipulation and pain after physical exertion) and a full physical exam (body weight, body temperature and heart rate). At the same time intervals, dogs serum samples were examined for biomarkers of kidney (BUN and creatinine), liver (bilirubin, ALT and AST) and heart and skeletal muscle (CK) functions. Findings of this investigation revealed that dogs receiving Crominex® 3+ (1000 μg chromium, 15 mg Amla extract and 15 mg purified Shilajit per day in two divided doses) exhibited a significant (P< 0.05) reduction in arthritic pain noted as early as after 90 days with a maximum reduction after 150 days of treatment. Pain level remained the same or slightly increased in the dogs receiving placebo. No significant change occurred in physical parameters or serum biomarkers in dogs on placebo or Crominex® 3+, which suggested that Crominex® 3+ was well tolerated by arthritic dogs. In conclusion, Crominex® 3+ significantly (P< 0.05) ameliorated arthritic pain and improved quality of life without causing any untoward effects in moderately arthritic dogs.
Presentation-Project RC-8828_Next_Generation of TiO2_eng.pdfAndriy Gonchar
The paper examines the antagonism between the key titanium dioxide pigments properties, such as Durability, Hiding Power, Dispersibility, Initial Gloss. The paper contains a brief history overview of TiO2 pigments, designed for applications where High and Superior Durability is needed. In the context of Project RC-8828, developed by RD Titan Group, TOV company (approximately, the research on this project will be finished in 2018-2019) the expected characteristics of the next generation Titanium Dioxide Grade are presented; this grade combines antagonistic properties: Superior+ Durability, High Hiding Power, Excellent Dispersibility and High Initial Gloss. Also the paper considers some problems of industrial implementation of the new generation pigments, related both to the development of appropriate technologies, and economic aspects of the commercialization of these technologies
Galvanization or galvanizing is the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot-dip galvanizing, in which the parts are submerged in a bath of molten zinc.
Presentation given by George Romanos of the National Center for Scientific Research “Demokritos” (NCSRD), Greece, on "Novel IOnic LIquid and supported ionic liquid solvents for reversible CAPture of CO2- IOLICAP" at the EC FP7 Projects: Leading the way in CCS implementation event, London, 14-15 April 2014
Lithium-Ion Batteries towards Circular Economy: A Literature Review of Opport...OlgaRodrguezLargo
Presentation of a literature review of opportunities and issues of recycling treatments for Lithium-Ion Batteries in SDEWES19 Conference, within the framework of the European Project CarE-Service.
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 776851.
GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
Guy Korland, CEO and Co-founder of FalkorDB, will review two articles on the integration of language models with knowledge graphs.
1. Unifying Large Language Models and Knowledge Graphs: A Roadmap.
https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
https://www.microsoft.com/en-us/research/blog/graphrag-unlocking-llm-discovery-on-narrative-private-data/
Connector Corner: Automate dynamic content and events by pushing a buttonDianaGray10
Here is something new! In our next Connector Corner webinar, we will demonstrate how you can use a single workflow to:
Create a campaign using Mailchimp with merge tags/fields
Send an interactive Slack channel message (using buttons)
Have the message received by managers and peers along with a test email for review
But there’s more:
In a second workflow supporting the same use case, you’ll see:
Your campaign sent to target colleagues for approval
If the “Approve” button is clicked, a Jira/Zendesk ticket is created for the marketing design team
But—if the “Reject” button is pushed, colleagues will be alerted via Slack message
Join us to learn more about this new, human-in-the-loop capability, brought to you by Integration Service connectors.
And...
Speakers:
Akshay Agnihotri, Product Manager
Charlie Greenberg, Host
Elevating Tactical DDD Patterns Through Object CalisthenicsDorra BARTAGUIZ
After immersing yourself in the blue book and its red counterpart, attending DDD-focused conferences, and applying tactical patterns, you're left with a crucial question: How do I ensure my design is effective? Tactical patterns within Domain-Driven Design (DDD) serve as guiding principles for creating clear and manageable domain models. However, achieving success with these patterns requires additional guidance. Interestingly, we've observed that a set of constraints initially designed for training purposes remarkably aligns with effective pattern implementation, offering a more ‘mechanical’ approach. Let's explore together how Object Calisthenics can elevate the design of your tactical DDD patterns, offering concrete help for those venturing into DDD for the first time!
Software Delivery At the Speed of AI: Inflectra Invests In AI-Powered QualityInflectra
In this insightful webinar, Inflectra explores how artificial intelligence (AI) is transforming software development and testing. Discover how AI-powered tools are revolutionizing every stage of the software development lifecycle (SDLC), from design and prototyping to testing, deployment, and monitoring.
Learn about:
• The Future of Testing: How AI is shifting testing towards verification, analysis, and higher-level skills, while reducing repetitive tasks.
• Test Automation: How AI-powered test case generation, optimization, and self-healing tests are making testing more efficient and effective.
• Visual Testing: Explore the emerging capabilities of AI in visual testing and how it's set to revolutionize UI verification.
• Inflectra's AI Solutions: See demonstrations of Inflectra's cutting-edge AI tools like the ChatGPT plugin and Azure Open AI platform, designed to streamline your testing process.
Whether you're a developer, tester, or QA professional, this webinar will give you valuable insights into how AI is shaping the future of software delivery.
DevOps and Testing slides at DASA ConnectKari Kakkonen
My and Rik Marselis slides at 30.5.2024 DASA Connect conference. We discuss about what is testing, then what is agile testing and finally what is Testing in DevOps. Finally we had lovely workshop with the participants trying to find out different ways to think about quality and testing in different parts of the DevOps infinity loop.
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
Do you want to learn how to model and simulate an electrical network from scratch in under an hour?
Then welcome to this PowSyBl workshop, hosted by Rte, the French Transmission System Operator (TSO)!
During the webinar, you will discover the PowSyBl ecosystem as well as handle and study an electrical network through an interactive Python notebook.
PowSyBl is an open source project hosted by LF Energy, which offers a comprehensive set of features for electrical grid modelling and simulation. Among other advanced features, PowSyBl provides:
- A fully editable and extendable library for grid component modelling;
- Visualization tools to display your network;
- Grid simulation tools, such as power flows, security analyses (with or without remedial actions) and sensitivity analyses;
The framework is mostly written in Java, with a Python binding so that Python developers can access PowSyBl functionalities as well.
What you will learn during the webinar:
- For beginners: discover PowSyBl's functionalities through a quick general presentation and the notebook, without needing any expert coding skills;
- For advanced developers: master the skills to efficiently apply PowSyBl functionalities to your real-world scenarios.
Essentials of Automations: Optimizing FME Workflows with ParametersSafe Software
Are you looking to streamline your workflows and boost your projects’ efficiency? Do you find yourself searching for ways to add flexibility and control over your FME workflows? If so, you’re in the right place.
Join us for an insightful dive into the world of FME parameters, a critical element in optimizing workflow efficiency. This webinar marks the beginning of our three-part “Essentials of Automation” series. This first webinar is designed to equip you with the knowledge and skills to utilize parameters effectively: enhancing the flexibility, maintainability, and user control of your FME projects.
Here’s what you’ll gain:
- Essentials of FME Parameters: Understand the pivotal role of parameters, including Reader/Writer, Transformer, User, and FME Flow categories. Discover how they are the key to unlocking automation and optimization within your workflows.
- Practical Applications in FME Form: Delve into key user parameter types including choice, connections, and file URLs. Allow users to control how a workflow runs, making your workflows more reusable. Learn to import values and deliver the best user experience for your workflows while enhancing accuracy.
- Optimization Strategies in FME Flow: Explore the creation and strategic deployment of parameters in FME Flow, including the use of deployment and geometry parameters, to maximize workflow efficiency.
- Pro Tips for Success: Gain insights on parameterizing connections and leveraging new features like Conditional Visibility for clarity and simplicity.
We’ll wrap up with a glimpse into future webinars, followed by a Q&A session to address your specific questions surrounding this topic.
Don’t miss this opportunity to elevate your FME expertise and drive your projects to new heights of efficiency.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Transcript: Selling digital books in 2024: Insights from industry leaders - T...BookNet Canada
The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
Presented by BookNet Canada on May 28, 2024, with support from the Department of Canadian Heritage.
Slack (or Teams) Automation for Bonterra Impact Management (fka Social Soluti...Jeffrey Haguewood
Sidekick Solutions uses Bonterra Impact Management (fka Social Solutions Apricot) and automation solutions to integrate data for business workflows.
We believe integration and automation are essential to user experience and the promise of efficient work through technology. Automation is the critical ingredient to realizing that full vision. We develop integration products and services for Bonterra Case Management software to support the deployment of automations for a variety of use cases.
This video focuses on the notifications, alerts, and approval requests using Slack for Bonterra Impact Management. The solutions covered in this webinar can also be deployed for Microsoft Teams.
Interested in deploying notification automations for Bonterra Impact Management? Contact us at sales@sidekicksolutionsllc.com to discuss next steps.
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
AI for Every Business: Unlocking Your Product's Universal Potential by VP of ...
Chromium problems
1. Ole Øystein Knudsen, Astrid Bjørgum
SINTEF Materials Technology
Materials Technology 1
2. n Part of a wider ongoing research project financed by the
Research Council and Norwegian light metals industry:
Light Metal Surface Science
n Participating companies
n Hydro Aluminium
n Elektro-Vakuum
n Noral Lighting
n Norsk Industrilakkering
n Profil-Lakkering
n DuPont Powder Coatings
n Jotun Powder Coatings
Materials Technology 2
3. n Chromium - why …. and why not?
n Properties and problems
n Regulation - EU and Norwegian
n Chromium free pre-treatments
n Redox reactions with precipitation
n pH controlled precipitation on the aluminium surface
n Molecules that deposit on the aluminium surface
n Strengthening the aluminium oxide
Materials Technology 3
4. n Focus in this presentation:
n Treatments for aluminium
n Commercially available processes
n Emphasis for each process:
n Basic principles for the formation of the coating
n Process / production friendliness
n Experiences
Materials Technology 4
6. n First patented in 1923
n Used extensively since for pre-
treatment before coating,
adhesive bonding and surface
finishing
n 43 000 tons of chromium was
used in metal finishing
operations in 1993
Materials Technology 6
7. n The chemicals contain:
n Hexavalent chromium (CrO3 or CrO42- or Cr2O72-)
n Hydrofluoric acid (HF)
n The hydrofluoric acid removes the oxide film on the
surface
n The hexavalent chromium reacts with the exposed
aluminium metal and a trivalent chromium oxide
precipitates
Cr2O72- + 2 Al + 2 H+ ® Cr2O3·H2O + Al2O3
Materials Technology 7
8. n Chromium oxide stabile in
alkaline solutions up to pH 15
n Chromium oxide is water
repellant (hydrophobic) and
may act as a barrier coating
towards water
n Self healing effect: hexavalent
chromium present in the
conversion coating that may
react at mechanical damages
n Passivating both the aluminium
matrix and the intermetallic
particles
Materials Technology 8
9. n Highly effective
n Preventing corrosion
n Adhesion promoter for organic coatings and adhesives
n Resilient: The process has low sensitivity towards
variation in process conditions
n Effective on most/all aluminium alloys
n Quality control: Skilled workers can tell the amount of
chromium on the surface by the color of the conversion
coating
Materials Technology 9
10. n Toxic
n Classified as human carcinogen
n Workers at the production line are concerned about their
health - liability for claims of workspace exposure
n Consumers are concerned about hexavalent chromium
present in products
n Concern about hexavalent chromium in the environment,
e.g. drinking water
n Treatment of waste
n Stringent disposal limits
n Increased costs for tracking inventories, monitoring, reporting
n Disposal of wastes containing chromium
Materials Technology 10
11. n Pacific Gas & Electric
n Deposits of hexavalent
chromium in the ground
n Hexavalent chromium leached
into the groundwater
n Cancer and other diseases
increased dramatically
n In 1993 PG&E settled for $333
million, the largest settlement
ever in a direct action lawsuit.
n California 2001: Law that limits
Julia Roberts as Erin Brockovich (2000)
the level of hexavalent
chromium in drinking water
Materials Technology 11
12. n EU directive 2000/53/EC: End-of life vehicle
n Every year 8-9 million tons of waste are produced from end-of life
vehicles
n Aim: to harmonize the treatment of this waste in order to reduce
environmental impact
n Increase recycling and reuse of materials
n Reduce and control the use of hazardous substances in vehicles
n Vehicles put on the market after 1 July 2003 shall not contain:
n lead, mercury, cadmium and hexavalent chromium
n Norway: Chromium on the B-list of hazardous substances
n Aim: Significant decrease in the use of chromium by 2010
Materials Technology 12
14. n Redox reactions with precipitation
n Molybdenum
n Manganese
n pH controlled precipitation
n Phosphate
n Titanium / zirconium based processes
n Cerium
n (Trivalent chromium)
n Coupling agents between aluminium oxide and binder
n Silanisation
n Self Assembling Molecules (SAM)
n Strengthening the aluminium oxide
n DC and AC anodizing
Materials Technology 14
15. n Molybdates Basic prinsiple
n Permanganates n Same formation mechanism as for
chromium
n Group 6B / 7B metal in high oxidation
state reacts with aluminium in redox
reaction:
n The 6B / 7B metal is reduced and
forms an insoluble oxide
n Aluminium is oxidized
n The insoluble oxide precipitate on the
aluminium surface and forms a
protective film
Materials Technology 15
17. n Molybdenium n Manganes
n Mo6+ reacts with Al and forms n Mn7+ reacts with Al and forms
Mon+, which precipitates as Mn4+, which precipitates as
oxides on the Al surface MnO2 on the aluminium surface
n Both processes gives a conversion coating that covers the
aluminium matrix
Materials Technology 17
18. n Molybdenium n Manganese
– Expensive + Good adhesion
– Moderate corrosion protection + Yellow color
– Poor adhesion properties
– More hydrophilic than
chromium - not as good barrier
coating
– Poor corrosion resistance
Materials Technology 18
21. n Phosphating
n Titanium / Zirconium based
processes
n Cerium (and other rare earth
metals)
n Trivalent chromium
Materials Technology 21
22. n Hydrogen evolution at cathodic
sites in the alloy (intermetallic
particles)
n pH increases near the
intermetallics
n The solubility of the oxide
decreases when the pH increases
n The film (oxide) presipitates
n The conversion coating is
therefore mainly formed on the
intermetallic particles
Materials Technology 22
23. n Originally developed for steel and extensively used on
steel and zinc
n Available in a number of variations where zinc, iron, nickel
or manganese are incorporated in the coating
n A sealer or passivator may be applied on the coating, e.g.
containing zirconium ions
n Problem: Al3+ ions in the bath will inhibit the coating
formation. By adding fluorides the Al3+ is bound in AlF63-
and precipitates
Materials Technology 23
24. n Phosphoric acid exists in four levels of protonation:
H3PO4 H2PO4- HPO42- PO43-
n pH at cathodic sites on the surface increases due to
hydrogen evolution:
2 H+ + 2 e- H2
n PO43- precipitates with aluminium or other metallic ions
present in the solution when the pH increases
Materials Technology 24
25. n Anodic dissolution of aluminium:
Al + 3 H2PO4- ® Al(H2PO4)3
n Secondary reactions take place:
Al(H2PO4)3 ® Al2(H2PO4)3 + 3 H3PO4
Al2(HPO4)3 ® 2 AlPO4 + H3PO4
n Net reaction:
2 Al(H2PO4)3 ® 2 AlPO4 + 4 H3PO4
Materials Technology 25
26. n Used in plants where both aluminium and steel
components are treated, e.g. in the automotive industry
n Perhaps the chromium free pre-treatment process that is
most frequently used on aluminium today
Materials Technology 26
27. + Good adhesion
+ Coating formation rate comparable to chromium
+ Pre-treat Al in same process as steel and zinc
– Less corrosion resistant than chromium
– Colorless and invisible on aluminium
Materials Technology 27
28. n Titanium and zirconium (also
hafnium) conversion coatings are
formed the same way
n The metal is exposed to a
solution of H2ZrF6 , H2TiF6 or
both
n Hydrofluoric acid removes the
aluminium oxide from the surface
n Near intermetallic particles,
where the pH is higher, the
fluorides hydrolyse and TiO2 /
ZrO2 precipitates
n The oxidation number for Ti/Zr is
+4 both in solution and coating -
no redox reaction
Materials Technology 28
29. n The coating is not homogenus -
precipitates on intermetallic
particles
n The amount of oxide precipitated
depends on the composition of
the alloy - the more intermetallic
particles the more coating
precipitates
n Thin coatings - in the order of 10
nm or 10 mg/m2
n For some processes a polymer is
included to seal the conversion
coating
n Ti and Zr oxides are stabile at pH
3 - 12
Materials Technology 29
30. + The coating forms rapidly - seconds
+ Good adhesion and corrosion resistance has been found
for some alloy/coating systems
– In other systems not - the results varies with alloy, thermo-
mechanical history of the alloy and organic coating
– The coating is invisible
Materials Technology 30
31. n Solution containing trivalent cerium (Ce3+) and hydrogen peroxide
(H2O2)
n Film formation takes place by process similar to the Ti/Zr mechanism
First: Later:
n The hydrogen peroxide n Dissolution of aluminium oxide
oxidizes the trivalent cerium on the rest of the surface
n Small cathodic particles
2 Ce3+ + H2O2 2 Ce4+
appears where the same
n Ce4+ precipitates at local precipitation process occurs
cathodes when pH increases n The islands grow into a
continuos film
H2O2 + 2 e- 2 OH-
Materials Technology 31
32. n Trivalent cerium hydroxide is
stabile at pH > 7
n Thickness
n Matrix: 100 - 200 nm
n Intermetallic particles: ~1 µm
n Precipitation on intermetallic
particles - decreases the
cathodic reaction rate
n Used in combination with
manganese which mainly builds
on the Al matrix
n The coating is colored
Materials Technology 32
33. + Colored coating
+ Good corrosion resistance and adhesion properties have
been reported, high Cu alloys in particular (2000)
– In other alloy / coating systems poor corrosion and
adhesion properties have been reported - The process
has to be adapted to each specific alloy
– Many process steps
– Building of the conversion coating takes long time
– Expensive
Materials Technology 33
35. Basic principle:
n Organic molecules with two functional groups
n One binds to the surface oxide
n The other to the organic coating
Materials Technology 35
36. n Relatively new process
n few experiences available
n few published results
n Less corrosion resistant than Ti/Zr based processes and
chromium
n Sensitive to surface cleanliness prior to application
Materials Technology 36
37. Basic principle
O- R O- H
R Si O- R + 3 H2 O R Si O- H + 3 R-OH
O- R O- H
R: ethyl / methyl
R: organic functional group R
-C3H6-NH3
O Si
-C3H6-O-CH-CH2
O O O
-C2H4-Si (OR)3 Al Al Al
Materials Technology 37
38. n Applied by exposing the surface
to a diluted solution of silanes in
water
n Homogenous
n 50-100 nm thick
n Cross linked via Si - O - Si
bonds into a three dimensional
network
Joop Mulder, Corrosion Management,
No 44, Nov./Dec 2001
Materials Technology 38
39. + Good adhesion properties, also wet adhesion
– Corrosion resistance not as good as chromium
– Emission of alcohols in the process, which may need
handling
– Sensitive to surface cleanliness
– Choice of organic functional group may be resin
dependant
Materials Technology 39
41. n The aluminium alloy is polarized
anodically
V
n Electrolyte: Diluted acid, e.g. 15
% sulfuric acid
e-
n The aluminium oxidizes:
2 Al + 3 H2O ® Al2O3 + 6 H+ + 6 e-
H2
n At the cathode hydrogen is
formed:
6 H+ + 6 e- ® 3 H2
H+
Counter
Substrate electrode
Materials Technology 41
42. n The oxide gets a hexagonal
structure
n A barrier layer in the bottom
~100 Å thick
n A porous layer 1 - 30 µm (pre-
treatment: ~1 µm)
n The thickness of the oxide layer
depends on:
n Electrolyte
n Temperature
n Current density
n Time of treatment
n Alloy composition
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43. n Traditionally used for surface
finishing:
n Several µm thick oxide
n Several minutes to build the
oxide
n Pre-treatment:
n ~1 µm is sufficient
n Faster
1 µm
TEM image of DC anodized AA6060
Materials Technology 43
44. n The aluminium is both anode
and cathode
n During cathodic hydrogen
evolution, degreasing also
takes place
n No need for degreasing prior to
AC anodizing
n Process temperature: 80°C
1 µm
TEM image of AC anodized AA6060
Materials Technology 44
45. + Corrosion resistance – Need for special equipment:
comparable to chromium power source
+ Easy to control metal removal – Not possible in spray lines
and oxide thickness – Adhesion usually somewhat
lower than for chromium
Hot AC
+ Few process steps
+ Anodizing + rinsing
+ Rapid process - seconds
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46. n GSB: Gutegemeinschaft fuer die Stueckbeschichtung von
Bauteilen, Germany
n Qualicoat: The rest of Europe
n Both have approved chromium free processes
n Ti/Zr based pre-treatments: Both
n Anodizing: Qualicoat
n Phosphating: GSB
Materials Technology 46
47. n Many of them contain hydro fluoric acid
n HF is also on the B-list of hazardous chemicals
n Fluorides: 10 mg/l limit in waste water
n No signals from Norwegian authorities or the EU regarding
changes in the attitude to HF
n New chemical compounds - do we know all their health
and environmental effects yet?
Materials Technology 47