A sustainable way of protecting materials against corrosion
Wear, tear and corrosion of building materials currently cost developed countries a 3-4 % loss in GDP every year. Billions of euros are spent annually on replacing corroded infrastructure. Thus, it should come as no surprise that the surface engineering of protective coatings is big business – and one that is critical to the competitiveness of EU industry. Currently, the two main techniques for protecting surfaces are hard chromium (HC) electro-plating and the application of tungsten monocarbide (WC) by thermal spray (TS). HC is a common, simple and cheap method of coating surfaces, providing high hardness levels, good wear and corrosion resistance. TS, on the other hand, sprays the melted coating materials directly onto the surface. Although both succeed at lengthening the lifespan of the material being protected, these approaches create environmental and health risks. As a result, there is high demand for less-hazardous methods and materials that offer the same – or a greater – amount of protection. The EU-funded PROCETS (PROtective composite Coatings via Electrodeposition and Thermal Spraying) project believes they have the answer: the use of nano-particles for producing superior composite coatings. “We intend to deliver protective coatings covering a wide range of applications and industries – including automotive, aerospace, metal-working, oil and gas and cutting tools – by utilising more environmentally-friendly materials than those currently being used,” explains project coordinator Dr Dionysis Bochtis. “This will allow industry to permanently replace the hazardous use of hard chromium and WC thermal spray.” Goodbye HC plating, hello nano-particles Although the project will only conclude in June 2019, several important results have already been achieved. For example, researchers produced nano-composite coatings with enhanced mechanical properties compared to HC and WC. Researchers also made significant progress in improving the structure and morphology of composite coatings – a major step towards increasing their resistance to wear, corrosion, impact damage and fretting. “These improvements open the door to the successful integration of nano-particles,” says Dr Bochtis. “This in turn will free a number of industries from their dependence on hard chromium plating, which will soon be greatly restricted by EU regulations.” Progress is also being made on the TS side of the equation. Here, researchers have developed a ‘green cermet’ that offers similar mechanical properties to WC, but with a drastic decrease in weight. A new generation of coatings This work isn’t just theory, as Dr Bochtis says researchers have already performed an initial pre-screening of the tribological behaviour of several electro-deposited and sprayed coatings under conditions that can be extended to real industrial scenarios. “Based on this pre-screening, the most promising candidate systems will be selected,” he says. “Moreover, different methodologies for materials testing and evaluation were developed and/or updated to better simulate the needs of the end-users and perform testing under realistic conditions.” PROCETS is well on its way to delivering a new generation of environmentally-friendly and health-conscious coatings based on reinforced nano-particles. “Upon completion of the project, I fully expect to see an accelerated market uptake of nanomaterials and products by the surface finishing sector,” adds Dr Bochtis.
Keywords
PROCETS, hard chromium plating, thermal spray, infrastructure corrosion, nano-particles, nanotechnology, composite coatings
