Several different thermal spray solutions are applied throughout the industry today. All of these work on the same fundamental basis: heating a feedstock material in powder or wire form causes it to partially or fully melt, at which point it can be sprayed towards a substrate. When the molten droplets impact the substrate, they form lamellae or “splats”, which build up to coat the surface and create a uniform coating.
Popular thermal spray solutions include the likes of plasma spraying, flame spraying, and wire arc spraying. These thermal spraying solutions use a different method to heat and propel the feedstock material, with different thermal spray solutions offering distinct advantages in specific applications.
The use of thermal spraying techniques is often strongly aligned with sustainable principles. There is a solid argument that thermal spraying solutions play a role in combating climate change.1
As surface coating techniques, thermal spraying solutions enable the modification of materials by modifying only the outer layer. In this way, thermal spraying solutions can be used to create components with advanced material properties without needing the entire bulk material to exhibit these properties. For example, components can be thermally sprayed with relatively scarce refractory ceramics (such as yttria-stabilized zirconia) to improve their heat resistance without making the entire component from that ceramic.
Thermal spraying solutions are typically used to extend the durability of components, thus extending their service life and, therefore, their sustainability. In addition, thermal spraying solutions (especially flame spraying) enable damaged mechanical parts to be salvaged, restored and recycled, maximizing their service life and preventing them from being replaced prematurely.
On top of this, thermal spray techniques directly enable technological advances that reduce greenhouse gas emissions. One such application is in thermal barrier coatings (TBCs) for automotive and aerospace engines, where thermal spray solutions enable more efficient engines by imparting heat resistance to engine components.2 Thermal spraying solutions are also implemented directly in the manufacture of solar cells and wind turbines.3
However, thermal spraying solutions are still relatively energy-intensive processes. While they do, in a sense, minimize the consumption of scarce materials by using them only at a “surface” level, they still consume these materials. Among these materials are rare earth elements like tungsten.
The main areas in which the sustainability of thermal spray solutions can be improved are gases, power consumption, and wasted raw materials.
While larger corporations can afford to spray with nitrogen and hydrogen, smaller manufacturers are limited to thermal spray solutions that use hydrocarbons like acetylene and propane, contributing to greenhouse gas emissions. Scaling up of hydrogen generators would help encourage uptake of lower-emitting thermal spray solutions. Additionally, producing coatings using clean fuels could be incentivized by governments.
The power consumption rate of different thermal spray solutions varies across a broad spectrum. The highest-power plasma spray guns can use over 200kW. To maximize sustainability, manufacturers should carefully consider the requirements of their thermal spray solutions and opt for the lowest-power technology feasible.
Many raw materials are wasted during thermal spraying (overspray). To maximize the sustainability of thermal spray solutions, manufacturers require a means of efficiently recycling this material; and efforts should be made to salvage and reclaim scarce materials such as tungsten for thermal spray applications.4
Thermal spraying solutions from Saint-Gobain
Saint-Gobain has a commitment to carbon neutrality by 2050. As world leaders in the thermal coatings industry, we’re striving to maximize the efficiency and sustainability of our thermal spray solutions.
We offer an overspray material collection service to minimize landfilling and reduce our customers’ carbon footprint. Our coatings enhance resistance to aggressive process environments such as wear, corrosion and high temperatures allowing for reduced waste and downtime.
To learn more about our sustainability commitments and how our thermal spray solutions tie into this, get in touch with us today.
References and Further Reading