SiC Coating by Thermal Spray made possible (SiCoat)

The mechanical, thermal, chemical and tribological properties of Silicon Carbide (SiC) are of high interest. These properties makes SiC an ideal material to be used in very demanding applications. However the main limitation of SiC is the lack of melting point, this means that Silicon Carbide goes directly from solid to gas state. The lack of melting point disables the use of thermal spray for producing SiC coatings. Therefore this project was established with the aim of bringing to the market such a demanding thermal spray coating. Since the start of this project, Seram Coatings has been able to move the production of a lab scale product to pilot scale. Throughout all the duration of the project, discussions with possible clients have taken place. The project has been key for preparing the ThermaSiC pilot production line for client qualification testing. Several kilos of qualification material have been produced with the current pilot line. The pilot product has been sent to different potential clients for testing. This has led to defining some key applications to prepare the pilot line for industrialisation. Among these key applications we can find break disks for both cars and bikes, plungers for the glass industry, and space applications among many others. The pilot material is being qualified for liquid fuel high velocity oxygen fuel (HVOF) and atmospheric plasma spray (APS) methods. A new processing route is being developed at the R&D facilities for densifying the current pilot product to make it more suitable for plasma.

Despite many global efforts, no one has been able to produce SiC thermal spray coatings. SiCoat has made it possible for Seram Coatings to enable the lab production of SiC coatings to pilot level, making it ready for the market. At the project start, Seram Coatings' production was limited to few kilograms per day. Within this project, the production has been upscaled to several hundred kilos per month. A new production site has been established with a potential capacity of several tonnes per day. The production of SiC feedstock materials for thermal spray has now been patented in several countries by Seram Coatings. And a new product using a metal matrix is patent pending. Seram Coating´s business model has changed from R&D-based to market-driven business model. Seram Coatings has established its core business in Norway (split between R&D in Trøndelag and production in Porsgrunn), extending the Norwegian process industry offerm, improving the Norwegian value chain for coating services.

SiC (Silicon Carbide) is one of the most attractive ceramic coating material for wear and corrosion protection due to its excellent mechanical, chemical and thermal properties. Therefore, SiC has attracted considerable interest for aerospace components (turbine blades, moving components, thermal barrier coatings for rocket nozzles), automotive parts (turbochargers, valve train, fuel injectors etc.), metal working tools (cutting tools, drill bits), etc. However, despite the attractive properties of SiC, the lack of melting point at atmospheric pressure (SiC tends to decompose or sublimate at 2500-2600 °C) makes it an impossible material to be thermally sprayed, thus limiting the number of processes that can be used for producing SiC coatings to Physical Vapour Deposition (PVD) and Chemical Vapour Deposition (CVD). The main drawback of these technologies is that CVD and PVD are costly and slow processes that are considered unsuitable for producing SiC coatings on large-scale machine components as items to be coated must fit into a low pressure/vacuum chamber, while thermal spray is more versatile and large samples can be coated in a very simple and effective procedure. In 2014 Seram Coatings succeeded for the first time in producing SiC coatings using thermal spray technologies enabling their use on large machine parts, hence opening a vast industrial market for such coatings. The technology was protected and patented and it needs now to be further developed according to specific working conditions. Experience over the last years showed that thermal spraying is a complex technology with many parameters having strong influence on the final properties of the coating. Therefore this projects aims at demonstrating the viability of applying SiC coatings on two different market applications (demonstrators), verify the feasibility of expanding the use of these coatings from an industrial perspective and upscaling the powder production for covering the market demands.