Materials.Business Weekly ⚙️

November 24, 2020

Quote of the week: “Life is a series of building, testing, changing and iterating.” - Lauren Mosenthal (Millennial, product designer, researcher and entrepreneur -Website- )​


From The Editor's Corner

THE FAITHFUL SQUIRE - Part I

Galvanic series

Luigi Galvani (1737–1798), Professor at the University of Bologna, was another on the list of recognized Italian scientists who contributed to the fundamentals of the current scientific knowledge. As a physician and physicist, Galvani was able to combine his efforts and identify both physiological and physical phenomena. Researching bioelectricity in 1780, he discovered that the nature of a pair of metals (the electrodes) played an important role in the flow rate of electricity along nerves. In the beginning, he used brass and Iron; then experimented with other pairs of metals. This was the discovery of the battery principles, but Galvani did not note that. However, Alessandro Volta (1745–1827), a friend of Galvani, used such effect and invented the galvanic cell or voltaic pile in 1800, using copper and Zinc as electrodes, and saltwater as the electrolyte.

Conditions are ready for the development of electrochemistry along the XIX Century, and some of the developments are labeled remembering Galvani. One of them concerns the arrangement of the pairs of elements or electrodes in a specific electrolyte, or galvanic series, according to their behavior as anodic or cathodic immersed in an electrolyte. An abbreviated list of materials acting as cell electrodes in seawater includes:

CATHODIC TREND

Platinum

Gold

316 Stainless steel

Nickel

Lead

Tin

Copper

Yellow brass

Chromium (plated on steel)

Mild steel, cast Iron

Aluminum alloys

Zinc

Magnesium

ANODIC TREND

Also, a cathodic trend means the option of finding such an element in a pure natural state. On the contrary, the anodic trend means less or none option of finding it as a pure natural element. Curiously, the first ones are classified as noble materials, while the others are called active ones. Such simple categorization is so powerful that many of the counter corrosion measurements are based on it. More noble materials are cathodically protected by others in the lower part of the list. This is the benefit of some of the pairs of metals used extensively in engineering. It is well known that steel is the engineering material par excellence, the “Master Metal.” This due to the good combination of mechanical properties. Nevertheless, its usual low corrosion resistance is a matter of concern, and one way is by pairing with other less noble, more active material.

The star steward

But who is the defender? We are talking about Zinc, one of the more reactive metals, or one of the more plebeian metals, withstands corrosive attack, protecting steel. From the thermodynamic point of view, Zn is extremely active. But from the kinetical standpoint, usually, the Zinc rate dissolution is very low because of passivation effects. These and some other reasons are more than enough to talk about the couple steel/Zn as one of the more important engineering pairs. Zn is a metallic chemical element, the first in group 12 of the Periodic Table. Consequently, it has a relatively lower melting (419.5°C) and boiling (907°C) points. The density of 7.134 g cm−3. Zn was known by Chinese, Indians, Greeks, and Romans more than 20 centuries ago but identified as a chemical element in 1746 by Andreas Marggraf (German chemist, 1709 – 1782). Some authors associate its name with the Latin word Zincum, which means a white thin layer of white sediments. Main ore sources are blende or sphalerite (ZnS), and hemimorphite (Zn4Si2O7(OH)2·H2O). The highest production comes from China, Australia, Peru, India, the USA, Mexico, Canada, Bolivia, Kazakhstan, and Ireland. Currently, yearly global production is around 13 million tons. The estimated world reserves are 1900 million tonnes.

As always, following the thermodynamic cycle of “returning to the earth,” Zn corrodes and goes back to their origins. For instance, corrosion products include oxides (Zincite, ZnO), sulfides (Wurtzite, ZnS), sulfates (Zincosite, ZnSO4), chlorides (Simonkolleite, Zn5Cl2(OH)8H2O), and carbonates (Smithsonite, ZnCO3, and Hydrocinzite, Zn5(CO3)2(OH)6).

On the shoulders of giants

People had spent more than 2000 years using Iron and its alloys, and living together with corrosion problems, without any truly effective defense. Just accepting a natural process like it is, but no counter measurements. Just bare metals exposed to the attack of the environment. However, in the XVIII Century, even at the alchemist times, there was news about the immersion of clean steel in molten Zn, and obtaining the characteristic silvered coating. Such a process was described in a paper presented to the French Royal Academy in 1742, and therefore Zn coated household utensils were fairly well known in parts of France during the second half of that Century -Source-.

Then, some years after the contributions by Galvani and Volta, in 1824, Sir Humphry David, assisted by Michael Faraday, published some papers describing the possibility of protection of copper by sacrificial anodes of Iron, Tin, or Zinc. This was the starting point of the cathodic protection technique, which was consolidated along the first half of the next century, mainly as an answer to the petrochemical industry requirements. In 1836, the French civil engineer, chemist, and inventor Stanislas Sorel (1803 – 1871) was the first to patent a process for coating steel by dipping in molten Zn. Sorel named the process “galvanizing,” an attractive word at that time because of the electric shocks proposed by Galvani, and reminding him again. In 1837, William Crawford awarded a similar British patent, too. The first in the field use of galvanized iron was done by the UK Navy at Pembroke Docks, Wales in 1844. According to the British Galvanizer Association, by 1850, the galvanizing industry was using 10,000 tons of zinc a year for the protection of iron. A great boost of galvanized steel happened during the first half of the XX Century, due to the two world wars, mainly.

A 2020 market report shows that consumption is growing. Nowadays, 60 percent of Zn produced worldwide is used for protecting steel against corrosion. Common products include sheet and strip, structure, pipe and tube, and wire and hardware. According to the end-user/application, approx. percentage by use of galvanized steel is distributed in a wide spectrum of sectors: Construction (36%), urban furniture (27%), agriculture (13%), transport infrastructure (9%), utilities (5%), and miscellaneous. A list of top key players in the market includes Baowu Group, ThyssenKrupp, POSCO, ArcelorMittal, Nippon Steel, and Sumitomo Metal, Hesteel Group, Hyundai Steel, Gerdau, United States Steel Corporation, China Steel Corporation, Tata Steel, and Valin Steel Group.

Why does a commoner act nobly?

The empirical and scientific developments have been approaching little by little, explaining various facts and behaviors, and opening new and more rational options. So now we can explain why a metal that is very far from the nobles is capable of acting nobly. In the beginning, it is good to think about the electrochemical corrosion cell established in common conditions of a corrosive attack like atmospheric, by soils, by water, or chemicals. The two electrodes, cathode under protected conditions, and anode under a dissolution regime are electrically connected, allowing the flux of electrons and, besides, connected through an electrolyte, allowing the flux of ions, too. Any anti-corrosive measurement means the intervention of such a cell. A physical, chemical, or electrochemical modification. In the case of galvanized steel, one of the counter measurements is the establishment of a physical barrier between the steel substrate and the corrosive environment by the Zn coating. Consequently, characteristics like thickness, impermeability, and compactness are directly related to the protective capacity. Furthermore, in the case of anticorrosive coatings, adherence with the substrate is relevant. Here, there is one of the advantages of hot-dip galvanizing, due to the metallurgical alloying between steel and Zn, and an intimate contact between them, avoiding the option of an inner surface or void. Instead, it is structured as a gradient of compositions from the inner steel substrate until the outer pure Zn.

Furthermore, Zn can give cathodic protection to the Fe alloys. A measure of this difference is found comparing the equilibrium potentials (Ep) against a standard counter electrode. As the Galvanic Series showed above, Zn is anodic to iron. Ep is -763 and – 440 mV vs. the Standard Hydrogen Electrode, respectively. In other words, there is a gradient of the potential of 323 mV, able to easily promote the establishment of an electrochemical corrosion cell between iron and its alloys and Zn. Where the Zn is dissolved, meanwhile the ferrous counter electrode is safeguarded. Usually, the last one is the material that must be protected and ends up sacrificed. Zn as a sacrificial anode gives some advantages as protection on uncoated areas of the substrate (scratches, holes, edges, and other defects). Also, some of the principles of cathodic protection are valid here. For instance, the current capacity of Zn, concerning the relation of cathodic and anodic areas (Zn and substrate exposed areas), is very important. Zn as a sacrificial anode must yield enough number of electrons per unit mass and should deliver these electric charges efficiently. Some calculations show that the theoretical efficiency of pure Zn is 820 Ah.kg-1. Accordingly, an actual anode furnishing 0.1 Ah permanently will lose 1 kg of Zn yearly. Nevertheless, factors concerning the kinetics of the electrode reactions significantly influence, too.


Variables of the process related to kinetics include corrosion products, their nature, amount, and so on. Also, the nature of the corrosive environment, and the way of the interaction between material and environment, or characteristics of the system material/corrosive. Talking about the nature of the corrosive environment, it is very well known the excellent behavior of galvanized steel in rural atmospheres, where protective action by conventional galvanized steel can last several decades. While in severe marine atmospheres, it lasts only a few years, at most -Source-. Moreover, considering the nature of the corrosion products, there is a passivation phenomenon associated to the generation of compounds like Zincite, Smithsonite, and Hydrozincite, tightly adherent, impermeable, and protective as an effective patina. In the end, a much better behavior of the material than the expected one. This is the main reason for the very good protection of steel by a much less noble Zn, a relatively cheap protection method that pays most of the time. Remember: Protection of materials and equipment is good business!

Prof. Carlos Arroyave, Ph.D. Editor.

www.arroyave.co


Materials Biz News

The blue mineral economy in the frame of a Circular Economy

Faced with the growing demand for minerals and a closer understanding of the seabed, deep-sea mining emerges as an option. But environmental problems are a very serious concern. The presence of nodules and other forms are promising sources of manganese, cobalt, lithium, copper, nickel, zinc, rare earth elements, and so on. Nevertheless, principles as the enunciated from the Circular Economy point of view must be considered, looking for further development, but guarantying a proper planet for the coming generations. Then, new agreements, new rules, and new frameworks must be established. In this direction, the World Economic Forum has published a paper showing possible ways to be followed -Read More-.

Put your headphones on and learn about protective paints and coatings

CARBOLINE is producing a series of podcasts devoted to discussing with recognized experts about industrial coatings and linings, problems, solutions, and painting and testing techniques -Listen-. Right now, there are available 158 episodes. Some of the examples of the latest topics considered are waterjet cleaning, coating technology used for water tank exteriors, galvanizing vs. zinc-rich coatings, coating technology used in wastewater treatment systems, new technology for fire tubes on upstream oil and gas process vessels, the value of third-party coating inspection, polyurethane coatings and linings for steel water pipe and fittings, common standards and their differences, and thick-film and thin-film coating systems.

Corrosion Under Isolation - CUI - lab tests

Our colleague Simon Daly, Business Development Manager - Corrosion Under Insulation (CUI) & High Heat coatings at Hempel A/S, is looking for a third party laboratory equipped with the chamber to carry out Cyclic CUI condensation testing as per ISO 19277 (Petroleum, Petrochemical And Natural Gas Industries - Qualification Testing And Acceptance Criteria For Protective Coating Systems Under Insulation). People with possibilities to offer something can contact Simon through LinkedIn -Contact-.

The infrastructure that we must take care of

The World Bank has published an interactive Global Infrastructure Map, as an analytics tool in progress, putting together several geospatial data layers -Read More-. Layers include geographic contexts, such as topography, climate, population, disaster risk, agricultural activity, and administrative boundaries. Energy (plants, grids, and nightlights), transport (roads, rail networks, seaports, and airports), and digital infrastructure (submarine cables) are considered. Global, regional, and national levels of analysis are feasible.


Jobs

Maintenance management - Sunshine, Australia

AkzoNobel (Sunshine, Australia) is seeking a maintenance planer. Requirements include a diploma in Mechanical, five or more years of industrial experience, including supervision, and handling skills of AutoCAD and CMMS (MEX or SAP PM or similar). Some of the duties to be assumed are related to the coordination, assessment, planning, and execution of preventative and breakdown maintenance.

Contributing to the strengthening of a young and vibrant corrosion research space - Doha, Qatar

The National Corrosion Center (at the Qatar Environment & Energy Research Institute of the Hamad Bin Khalifa University, https://www.hbku.edu.qa/en/qeeri/corrosion-center), launched one year ago, is inviting to apply for temporary contracts as post-doc stays in the area of corrosion engineering. The basic requirement is an undergraduate degree in Materials, Corrosion, Mechanical, or Chemical engineering. Industrial experience is a bonus. Interested persons can contact its senior research director, Dr. Hanan Farhat.

Mold Design Engineer - Nogales. Mexico

Eaton at Nogales (Mexico), is calling for applications for a vacancy as a Mold Design Engineer. Some of the basic qualifications are an engineering degree (Mechanical, Metallurgical, Polymers, or Tool), 5 or more years of experience in similar positions, and advance English. Skills in ethics, learning agility, or accountability, are a bonus.


Networking & Knowledge Exchange

A salient meeting point for science and materials engineers - Virtual

The Indian Institute of Technology Indore – IITI, is organizing the “11th International Conference on Materials Processing and Characterization” - ICMPC 2020, to be held from 15th to 17th December 2020. According to the organizers, this conference is mainly aimed at major sectors of advanced processing, material characterization, modeling and simulation, properties, performance, and device fabrication. The list of keynote speakers includes Prof. Glenn S. Daehn (The Ohio State University, USA), Prof. Horst Hahn (Karlsruhe Institute of Technology, Germany), Prof. K Narasimhan (IIT Bombay), Dr. Manoj Gupta (NUS, Singapore), and some other recognized experts. Proceedings will be published in an Elsevier journal, and all the papers will be indexed through Scopus.

Innovative materials for a better life - Virtual

M2I, The Materials Innovation Institute, a network devoted to the Triple Helix industry-academy-government across the Netherlands and Europe, invites you to attend the “Meeting 2020 Materials”, an event supported by the 4TU. Research Centre High-Tech Materials (https://www.4tu.nl/htm/en/) and the Bond for Materials Knowledge (BvM) network (http://www.materialenkennis.nl/). The meeting will be held on December 14th and 15th 2020. Scheduled activities include talks, workshops, and networking. Attendance is free of charge and open for everyone interested in materials development.

High-level training in the times of the Corona - Virtual

NACE International has moved a list of its traditional courses to the digital space. All led the same instructors, include the same technical content and identical reference material and coursework. Subjects include CIP Level 1, CIP Level 2, CIP Level 3, CIP Level 4, Corrosion Control in the Refining Industry, Designing for Corrosion Control, Internal Corrosion for Pipelines (advanced), Strategy for Corrosion Management, and Marine Coating Technology.

Looking at integrity assessment - Virtual

TWI, as part of its cycle of webinars, is organizing a talk about ‘Fracture Integrity and Hydrogen Embrittlement’ to be held on December 9th, 2020, from 13:30 to 14:30 (London time). Speakers will be Muhammad Ali (Manager – Fracture Integrity Management section, Materials and Structural Integrity Group) and Menno Hoekstra (Technology Manager - Sour Testing). This seminar will be mainly addressed to Structural Integrity Engineers and Asset Integrity Managers. Subjects to be covered include Engineering Critical Assessment – ECA - of structures operating under conditions potentially leading to hydrogen embrittlement, and challenges and possible solutions related to fracture resistance testing of nominally tough materials in hydrogen embrittlement promoting environments to generate valid ECA input data.

"Materials science and advanced technologies for better corrosion protection" - Budapest, Hungary

The title above is the motto of the next European Federation of Corrosion’s annual conference, EUROCORR to be hosted by the Hungarian Corrosion Association, HUNKOR, in Budapest, Hungary, from 19th to 23rd September 2021. 12 to 14 parallel sessions will run, some dealing with general corrosion problems and some others focusing on specific industry subjects. The deadline for abstract submission is 19th January 2021.

Photo by Mika Baumeister on Unsplash