WP3: Design and realisation of a new prototype of portable unit for in situ repair

Lead by: IMPACT
Participating partners: POLIMI, VN, TWI, NAU KHAI, URJC, METALOGIC, AVIO, EADS
Duration: December 2013 – November 2015 (M07-M30)

Overview: Challenges and current SoA

The goal is to be able to do on-site repairs with cold spray by a portable cold spray system. This system has to be very flexible in use and reproducible in operation. Therefore several components for repair jobs may be necessary to apply coatings on site, e.g. at the aircraft. Generally the challenge is the handling of the entire process on site, including gas- and power supply, etc. SoA are hand hold cold spray systems like, ASB 2000, Centerline, Dymet.

Main Objectives

WP3 will be responsible for the validation of new definitions provided by the other research WPs. In particular, partners will seek to test and validate a new optimised Cold Spray portable unit as well as to realise and validate new nozzles for specific applications and components. Another aspect of this research will include the evaluation of the coatings obtained with the innovative systems.

Related Activities

Task 1: design and put on trial of a new and optimised Cold Spray portable unit

Subtask 1.1 analysis of preliminary considerations

Based on the actual commercially available Cold Spray portable units, and on the obtained simulation results in WP2, a set of potential materials for the Cold Spray powder will be discussed and chosen. The specific parameters to be considered for the choice of materials are:

  • better flow characteristics in the designed nozzle;
  • the critical velocity of flow for the specific powder material and substrate;
  • improved mechanical properties obtained at the end of the CS process on the substrate;
  • a lower level of imposed damage on the substrate.

Recommendations for choosing of WC-Co, WC-Ni and other compositions for optimized nozzle geometry to obtain the improved mechanical properties at the end of the CS process on the substrate will be provided.

Subtask 1.2: Design of a Cold Spray portable unit

The task will develop the engineering design of a Cold Spray portable unit optimized for treatment of the selected alloys. The task will also undertake the development of the optimized Cold Spray prototype portable unit.

Subtask 1.3: Trial of the systems with different nozzles and production of a preliminary set of coatings (on specimens)

The task will examine preliminary tests of Cold Spray applications using the portable unit. TWI and Veneto Nanotech will provide the trial for the prototype systems and nozzles, as they have a flexible facility set up for such purposes, able to deliver gas at up to 40 bar at 110 m3/hour. SprayWatch® particle diagnostics data (for measuring particle size and velocity distributions) will be used in order to feed back into further iterations of the process modelling in WP2.

Subtask 1.4.Design and testing the powder feeder for small size (1-10 micron) particles with high initial velocity preventing coagulation of small particles in the metering unit

The design of the powder feeder will be examined based on a new principal, vortex trajectory-type of transport gas and particles. This will allow the increase of increase the particles’ initial velocity, while at the same time the tangent direction of the particles’ movement will destruct coagulated particles, and decrease humidity influence on particles’ flowability. Preliminary testing of vortex-type powder feeder for selected alloys will be planned and carried out.

Task 2: Design and put on trial of new and specific nozzle for specific and innovative applications

Subtask 2.1 Design of a new nozzle for coating inner (out of view) surfaces

The task will specifically examine the engineering design of a new gun to be used on a steady/mechanized unit, able to spray in out of view area like inner diameters and inner surfaces. The development of compact non-symmetric and non-rotating nozzles for particle stream rotating up to 90 degrees will be carried out. Additionally, the results of previous numerical analysis will be taken into consideration in the development of the new nozzle.

Subtask 2.2 Realization of a prototype of a nozzle for coating inner (out of view surfaces)

The The task will be responsible for the manufacturing of the new nozzle based on the research, definitions and considerations received from others tasks.

Subtask 2.3: Put on trial of the systems with the new nozzle and production of a preliminary set of coatings (on specimens)

The task will in detail examine the characteristics of the new nozzle and explore optimization routes in the process. In particular, it will evaluate the gas and powder flowability, the particle velocity and the velocity distribution. Another aspect of this research will include the evaluation of the deposition efficiency and coating thickness homogeneity in comparison with traditional straight geometry nozzles.

Task 3: Characterisation of deposited coatings obtained with innovative systems and nozzle and comparison with coatings obtained with standard commercial systems

Subtask 3.1: Preliminary basic characterization of coatings deposited with the new Portable Unit and comparison to coatings obtained using a steady-system

Preliminary physical and mechanical characterization of the samples will take place involving standard testing procedures as well as comparison against the properties of coatings obtained with a state-of-the-art, high pressure, mechanised Cold Spray system.

Bond strength, metallurgical analysis (porosity, substrate-coating interface quality) as well as corrosion and oxidation resistance will be studied and used as the main screening tests to assess the effect of cold-sprayed process parameters on the different materials deposited in the various substrates.

Samples passing previously defined quality criteria will be further characterized in terms of their corrosion resistance. The partners will realize a comparison with literature data in terms of corrosion and oxidation resistance as well as with respect to cold-sprayed samples using stationary Cold Spray plants. Optical microscopy (OM), X-ray diffraction (XRD) and different surface analysis techniques such as SEM coupled with EDX, shall be used in order to characterize the surface and in depth cold deposited coatings in an attend to correlate corrosion performance with coating features and Cold Spray processing parameters. The RTD partners involved in the characterization process above will be in a strong collaboration and interaction for receiving feedback devoted to optimise the design procedure.

Subtask 3.2: Preliminary basic characterization of deposited coatings with new nozzles on specific components and specimens and comparison to coatings obtained using the standard nozzles

Preliminary physical and mechanical characterization of the samples will take place involving standard testing procedures. These will be also compared against the properties of coatings obtained with a state-of-the-art, high pressure, mechanised Cold Spray system operating commercial nozzles. Basic characterization will include geometrical and metallurgical (morphology, microstructure, porosity) features, as well as cohesion and adhesion following TCT and ASTM-C633. Finally, the wear performance of these coatings should be compared with those processed using a steady cold spray system. The RTD and industrial partners involved will be in a strong collaboration and interaction for receiving feedback devoted to optimise the design procedure the and repair requirements.

Expected Results beyond the SoA

The research to be realized will result in the development of a new Cold Spray portable unit. Initially the engineering design and a first prototype will be develop, followed by a thorough validation on industrial environments. The research will also look into the design and realization of innovative nozzles for depositing on out-of-view surfaces. A final report will summarize the findings of the final implementation and validation tests, clearly opening the way for the development of a new Cold Spray portable unit.

Progress

June 2013-May 2014 (M01-M12)

AIRBUS GROUP together with IMPACT visited CASSIDIAN and defined potential parts for repair using cold spray. In parallel, AVIO GROUP (GE) selected possible parts.

IMPACT´s task is to develop and manufacture a mobile system consisting of a hand-hold gun with integrated heater, a small powder feeder and an N2 gas supply. Furthermore, IMPACT has developed an inner coating device (ID gun) for the repairing of bore holes with varying diameters. The ID gun will be used for the repair of Aluminium housings, casing covers and other aircraft parts of high value. It can be used for a minimum diameter of 80mm. This prototype is already produced and will be delivered to VN for further tests.

The nozzle for this device was calculated by NAU-KHAI and manufactured by IMPACT. The prototype of the new small powder feeder for the mobile system is in production and modifications are currently in process. IMPACT engineers are busy on the design of the mobile system; the basic design of the hand-hold gun is ready for further discussions. IMPACT will execute the next development steps in close cooperation with the project partners. At the end of the project it should be possible to repair aircraft parts with the use of the mobile system, without costly dismounting and reassembling.

June 2014-November 2014 (M13-M18)

IMPACT is currently busy on the design of the hand hold gun for the mobile system. Together with AIRBUS GROUP they are discussing the possibilities of a flexible and light weight gun; due to a better accessibility to the repair parts the initial design (gun with integrated heater) had to be revisited. Furthermore, they are considering that a gun with integrated heater can weigh approximately 10kg, which is too heavy to guarantee a safe and easy handling.

In addition, two variations of a mobile system will be presented during the next CORSAIR meeting. Once these will be discussed and agreed among the partners, IMPACT will initiate the detailed design work and production.

KHAI delivered the drawings for the new powder feeder; this component is expected to be integrated into the mobile CG system. IMPACT manufactured a prototype of this new designed powder feeder and is currently running the first tests. The ID gun with adapter for the existing KINETIKS gun was developed, manufactured by IMPACT and delivered to VN for spray trials. In addition, 4 pieces of nozzle type: “IMP TECH NITRO”, were calculated by KHAI and supplied to VN.

December 2014-May 2015 (M19-M24)

Impact is busy on the development and manufacturing on the portable spray unit. Meanwhile the hardware is assembled to 90% and we plan the start up within the next 8 weeks. Due to some additional modifications on the new KHAI powder feeder we can use the IMPACT feeder for the first trials. The advantage of the KHAI powder feeder would be the light weight of less than 10Kg, compared with the IMPACT feeder what has a weight of 45Kg. After a successful start-up we will spray repair parts supplied by Airbus, Avio and Iberia.

June 2015-February 2016 (M25-M33)

The portable cold spray unit was finally assembled and tested in IMPACT. The portable spray system requires N2 gas supply, compressed air and electrical connections and can be easily transported to the repair site. The cold spray unit has removable powder feeder and gas pre-heater, allowing to access approx. 7m from the unit itself and use for repair areas with difficult accessibility. The portable cold spray unit was successfully tested with several Al alloys e.g. AA7050, AA2024, CP-Al. The first repair application on a worn out part of the wing fillet of the Transall C160 aircraft was carried out. The repaired part was sent for final machining and inspection. After the complex testing and coating development IMPACT plan to develop more repair application using the portable spray system in cooperation with AIRBUS, AVIO and IBERIA.


 

The activities related to the CORSAIR research are being organized in the following Work Packages (WPs):