Scientists develop life-saving chrome

September 20, 2005

British scientists have developed a safer and more versatile alternative to chrome electroplating, the coating found on vintage car bumpers, steel camshafts, and fixtures such as door furniture and light fittings.

Chrome electroplating protects from corrosion and adds an aesthetically pleasing sheen, but chromium comes with serious health risks and chromium compounds have been shown to cause cancer.

Speaking at an Institute of Physics conference in Chester, UK, Professor Robert Akid warns that workers are being exposed to chromium compounds that are potentially cancer-causing and says that a safer alternative is much needed. He told the conference, Novel Applications of Surface Modification, organized by the Applied Physics and Technology Division of the Institute of Physics, that he and his colleagues are developing an alternative that will not only be safer but cuts down on costs by reducing the numerous processing stages associated with conventional electroplating.

Professor Akid, who is Head of the Structural Materials & Integrity Research Centre at Sheffield Hallam University, is developing a so-called "sol-gel technology" which is a colloid with nanoparticles in a solvent that can form a gel. A metal object is sprayed with or dipped into the sol-gel system and it quickly forms a gel-like layer on the object's surface. The solvent is then removed by evaporation and the coating cured, or hardened. Akid says that the sol-gel approach can be used to coat a wider range of metals than electroplating methods.

Professor Akid said: "These inorganic-organic hybrid coatings have the potential to become an effective method of producing an alternative low-cost anti-corrosion or functional coating. The technology can be formulated and cured to give highly corrosion resistant, ceramic-based coatings. The method uses a range of cure temperatures and coatings are cured rapidly. The chemistry of the formulations has also been developed to provide sol-gel solutions that have a good shelf life."

There are technical issues yet to be addressed by the Sheffied team, however. For instance, a pre-requisite for such anticorrosion coatings on metals, such as aluminium and other metal surfaces, including zinc, stainless steel, and magnesium, is that they should be sufficiently thick, to give adequate lifetime and hard enough to be protected from scratching and abrasion.

Until now, sol-gel derived layers can be formed only up to two or three hundred nanometers in thickness with a single-dip. Akid explains that double dipping to produce multiple coatings is possible but this has the potential drawback of a reduction in coating properties.

Akid said: "The new type of protective coatings not only have high corrosion resistance and don't easily release their constituent ions into the environment, but are also non-toxic." Akid and his colleagues have used sol-gel mixtures that produce aluminium oxide and silicon oxide coatings with a chemical component that allows them to bind to the metal component's surface.

The team's preliminary corrosion tests, including so-called potentiodynamic polarisation in which an electric current is used to induce corrosion showed that the coating possesses excellent corrosion resistance properties compared with uncoated samples and other pre-treatments. The researchers have also carried out mechanical tests and have shown with a simple scratch and bend tests that the coatings exhibit very good adhesion to the substrate.

As a further test of the durability of the coating, the researchers also immersed coated components in an exfoliation solution consisting of nitric acid and chloride with very high acidity, pH1. This simulates the kind of corrosion that aluminium alloy aerospace components might experience, albeit an accelerated test. Akid explained that their test results compared well with similar tests on bare and chromic acid anodised samples. The sol-gel hybrid coating showed little attack even after almost 200 hours immersion. The chromic acid anodised components were pitted after this time and so failed the test, while the bare simple was extremely corroded. The team used scanning electron microscopy (SEM) to identify the nature of the attack, general or localised corrosion.
-end-
Notes to editors:

For further information or interviews contact: David Reid, Institute of Physics, Tel: 020-7470-4815 or Mobile: 0794-632-1473. E-mail: david.reid@iop.org.

Professor Akid's presentation will be delivered at 12pm on Wednesday 21 September 2005 at the Institute of Physics conference Novel Applications of Surface Modification.

Novel Applications of Surface Modification Organized by the Applied Physics and Technology Division of the Institute of Physics, is taking place 18-21 September 2005 at Chester College, Chester, UK.

Further information about this conference: http://conferences.iop.org/APTD/.

Press release researched and written by science writer David Bradley, http://www.sciencebase.com.

The Institute of Physics is a leading international professional body and learned society with over 37,000 members, which promotes the advancement and dissemination of a knowledge of and education in the science of physics, pure and applied. It has a world-wide membership and is a major international player in:

The Institute is a member of the Science Council, and a nominated body of the Engineering Council. The Institute works in collaboration with national physical societies and plays an important role in transnational societies such as the European Physical Society and represents British and Irish physicists in international organisations. In Great Britain and Ireland the Institute is active in providing support for physicists in all professions and careers, encouraging physics research and its applications, providing support for physics in schools, colleges and universities, influencing government and informing public debate.

IOP Publishing

Related Physics Articles from Brightsurf:

Helium, a little atom for big physics
Helium is the simplest multi-body atom. Its energy levels can be calculated with extremely high precision only relying on a few fundamental physical constants and the quantum electrodynamics (QED) theory.

Hyperbolic metamaterials exhibit 2T physics
According to Igor Smolyaninov of the University of Maryland, ''One of the more unusual applications of metamaterials was a theoretical proposal to construct a physical system that would exhibit two-time physics behavior on small scales.''

Challenges and opportunities for women in physics
Women in the United States hold fewer than 25% of bachelor's degrees, 20% of doctoral degrees and 19% of faculty positions in physics.

Indeterminist physics for an open world
Classical physics is characterized by the equations describing the world.

Leptons help in tracking new physics
Electrons with 'colleagues' -- other leptons - are one of many products of collisions observed in the LHCb experiment at the Large Hadron Collider.

Has physics ever been deterministic?
Researchers from the Austrian Academy of Sciences, the University of Vienna and the University of Geneva, have proposed a new interpretation of classical physics without real numbers.

Twisted physics
A new study in the journal Nature shows that superconductivity in bilayer graphene can be turned on or off with a small voltage change, increasing its usefulness for electronic devices.

Physics vs. asthma
A research team from the MIPT Center for Molecular Mechanisms of Aging and Age-Related Diseases has collaborated with colleagues from the U.S., Canada, France, and Germany to determine the spatial structure of the CysLT1 receptor.

2D topological physics from shaking a 1D wire
Published in Physical Review X, this new study propose a realistic scheme to observe a 'cold-atomic quantum Hall effect.'

Helping physics teachers who don't know physics
A shortage of high school physics teachers has led to teachers with little-to-no training taking over physics classrooms, reports show.

Read More: Physics News and Physics Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.