Final Report Summary - OFIENGINE (Development of the new termal spraying equipment and technology for production of components for marine transport engines)
The main objective of the OFIENGINE project was the development of new thermal spray equipment for the production of components for marine transport application. This technology should allow the manufacturing of marine engine components with improved technical and service characteristics.
A comprehensive screening test was performed to establish a suitable parameter window to process carbide based materials according to the requirements of the industrial partners in terms of feed stock powders of interest and the expected coating properties. The information collected during this initial project stage offered the basis for the design and manufacture of a new OFI gun prototype, which has been already validated for the deposition of high quality cermet type coatings. Beside the spray gun as main component, there are other four different peripheral modules that were designed and / or adapted to fulfil the overall requirements of the new OFI system. These are the main controller, the chiller unit, the gas lines (including the modular controllers) and the powder feeder.
There were at least seven different mean process parameters that have to be optimised in close correlation to the gun configuration. It includes five gas flow rates, the stand-off distance to the substrate and the powder feeding rate. The results achieved in this first screening test offered the basis for the further optimisation of the OFI gun. The developed gun prototype was then manufactured and validated with base on the results newly achieved with a WC-17Co powder.
Three different demonstrators were manufactured following the specifications collected in work package 1 (WP1), i.e. piston crown, piston pin and valve spindle. The piston crown was coated with an anti-adherent Cr3C2-NiCr based layer using the new OFI prototype and sent to the end user (client from KANTER). The piston pin and the valve spindle were coated with WC-17Co and Cr3C2-NiCr layers, respectively. Following the specifications of WP1, both components had to be finished to achieve the desired surface quality. Only the surface finishing achieved on the piston pin fulfilled the specifications, and thus, only this component was sent to the end user. In order to guarantee the quality of the coating, a control sample was prepared for each demonstrator manufactured during the project. The same were characterised and validated with the results previously achieved on button samples.
The modelling task has been divided in four sub-tasks corresponding to the various subprocesses of the system comprising the whole stage of the process, i.e. plasma formation, combustion, expansion of the flame in the barrel and in the ambient air. The work performed during the project was related to modelling of:
1) the formation of the argon plasma in the DC. plasma torch;
2) the mixing of the fuel (CH4) and oxidant (O2) gases with the high temperature plasma jet (Ar), ignition of the diffusion flame in the pressurised combustion chamber and development of the flow in the laval nozzle;
3) the mixing of the plasma-flame jet flow with the ambient gas;
4) the injection, cinematic and thermal behaviour of powder particles in the gas flow.
In relation to the optimisation of the OFI process, it should be underlined that the optimisation of the system was carried out in parallel with the modelling tasks. The simulation results helped to improve the design of different gun modules in an early stage of the project, i.e. gas injector for auxiliary gas (N2) and fuel.
The consortium agreed to focus the work on the development of an OFI prototype for the production of novel WC-Co and Cr3C2-NiCr based coatings to assess the wear and corrosion protection needs of three main diesel engines components: valve spindles, piston crowns and piston pins.
The design of the OFI spray system has been accomplished following a modular concept. The peripheral installations (i.e. cooling system, powder feeder and gas lines) were carefully designed / selected and manufactured to fulfil the technical requirements of the new gun prototype and ensure the operation of the system in a safe and reproducible way.
The control software has been developed following a user friendly concept, which will allow the operation of the system under different levels of access, i.e. full access as process designer or 'engineer modus', limited access as basic operator, visitor, etc. In general, the system will allow the specification of set points, the monitoring of present values, selection of gas lines, plasma parameters and powder feeder parameters, execution of calibration procedures, development and management of safety protocols, printing, recording and file saving.
The new gun prototype was manufactured and validated for the development of high quality cermet type and amorphous / nanostructured steel coatings. Nevertheless, the same also features a flexible modular design which should offer the possibility to tailor the gun configuration for materials with the most different chemical and physical nature. Three of the demonstrators scheduled in WP1 for marine engines have been manufactured, i.e. piston crown, piston pin and valve spindle.
According to the predicted results from the third simulation step dealing with the mixing of the plasma-flame jet flow with the ambient gas, the gas jet velocity (250 m/s) and temperature (180 K) are slightly increased by the adding of a plasma source. This increase can be explained by a better mixing of the fuel and oxidant thanks to a higher turbulence level reached with the plasma source and the higher temperature of the ignition flow that favours the appearance of the methyl radical. The predictions showed a rather good agreement with the measured external gas flow temperature and the photographs done of the shock waves.
The last simulation step dealt with the prediction of the injection and the cinematic and thermal behaviour of particles in the flame. A particle melting model was implemented in the CFD code fluent. The model was validated by in-flight particle measurements on WC- 17Co particles. Particle velocity and particle spray width are well predicted by the model but their temperature and melted fraction are underestimated, about 280 K for the temperature. This discrepancy is probably due to the assumptions of uniform temperature in the particles that is not valid due to their important porosities. Nevertheless, this assumption is usually adopted in HVOF modelling. It can be therefore stated, that the developed model gives good trends.
A comprehensive screening test was performed to establish a suitable parameter window to process carbide based materials according to the requirements of the industrial partners in terms of feed stock powders of interest and the expected coating properties. The information collected during this initial project stage offered the basis for the design and manufacture of a new OFI gun prototype, which has been already validated for the deposition of high quality cermet type coatings. Beside the spray gun as main component, there are other four different peripheral modules that were designed and / or adapted to fulfil the overall requirements of the new OFI system. These are the main controller, the chiller unit, the gas lines (including the modular controllers) and the powder feeder.
There were at least seven different mean process parameters that have to be optimised in close correlation to the gun configuration. It includes five gas flow rates, the stand-off distance to the substrate and the powder feeding rate. The results achieved in this first screening test offered the basis for the further optimisation of the OFI gun. The developed gun prototype was then manufactured and validated with base on the results newly achieved with a WC-17Co powder.
Three different demonstrators were manufactured following the specifications collected in work package 1 (WP1), i.e. piston crown, piston pin and valve spindle. The piston crown was coated with an anti-adherent Cr3C2-NiCr based layer using the new OFI prototype and sent to the end user (client from KANTER). The piston pin and the valve spindle were coated with WC-17Co and Cr3C2-NiCr layers, respectively. Following the specifications of WP1, both components had to be finished to achieve the desired surface quality. Only the surface finishing achieved on the piston pin fulfilled the specifications, and thus, only this component was sent to the end user. In order to guarantee the quality of the coating, a control sample was prepared for each demonstrator manufactured during the project. The same were characterised and validated with the results previously achieved on button samples.
The modelling task has been divided in four sub-tasks corresponding to the various subprocesses of the system comprising the whole stage of the process, i.e. plasma formation, combustion, expansion of the flame in the barrel and in the ambient air. The work performed during the project was related to modelling of:
1) the formation of the argon plasma in the DC. plasma torch;
2) the mixing of the fuel (CH4) and oxidant (O2) gases with the high temperature plasma jet (Ar), ignition of the diffusion flame in the pressurised combustion chamber and development of the flow in the laval nozzle;
3) the mixing of the plasma-flame jet flow with the ambient gas;
4) the injection, cinematic and thermal behaviour of powder particles in the gas flow.
In relation to the optimisation of the OFI process, it should be underlined that the optimisation of the system was carried out in parallel with the modelling tasks. The simulation results helped to improve the design of different gun modules in an early stage of the project, i.e. gas injector for auxiliary gas (N2) and fuel.
The consortium agreed to focus the work on the development of an OFI prototype for the production of novel WC-Co and Cr3C2-NiCr based coatings to assess the wear and corrosion protection needs of three main diesel engines components: valve spindles, piston crowns and piston pins.
The design of the OFI spray system has been accomplished following a modular concept. The peripheral installations (i.e. cooling system, powder feeder and gas lines) were carefully designed / selected and manufactured to fulfil the technical requirements of the new gun prototype and ensure the operation of the system in a safe and reproducible way.
The control software has been developed following a user friendly concept, which will allow the operation of the system under different levels of access, i.e. full access as process designer or 'engineer modus', limited access as basic operator, visitor, etc. In general, the system will allow the specification of set points, the monitoring of present values, selection of gas lines, plasma parameters and powder feeder parameters, execution of calibration procedures, development and management of safety protocols, printing, recording and file saving.
The new gun prototype was manufactured and validated for the development of high quality cermet type and amorphous / nanostructured steel coatings. Nevertheless, the same also features a flexible modular design which should offer the possibility to tailor the gun configuration for materials with the most different chemical and physical nature. Three of the demonstrators scheduled in WP1 for marine engines have been manufactured, i.e. piston crown, piston pin and valve spindle.
According to the predicted results from the third simulation step dealing with the mixing of the plasma-flame jet flow with the ambient gas, the gas jet velocity (250 m/s) and temperature (180 K) are slightly increased by the adding of a plasma source. This increase can be explained by a better mixing of the fuel and oxidant thanks to a higher turbulence level reached with the plasma source and the higher temperature of the ignition flow that favours the appearance of the methyl radical. The predictions showed a rather good agreement with the measured external gas flow temperature and the photographs done of the shock waves.
The last simulation step dealt with the prediction of the injection and the cinematic and thermal behaviour of particles in the flame. A particle melting model was implemented in the CFD code fluent. The model was validated by in-flight particle measurements on WC- 17Co particles. Particle velocity and particle spray width are well predicted by the model but their temperature and melted fraction are underestimated, about 280 K for the temperature. This discrepancy is probably due to the assumptions of uniform temperature in the particles that is not valid due to their important porosities. Nevertheless, this assumption is usually adopted in HVOF modelling. It can be therefore stated, that the developed model gives good trends.
