The CORSAIR project is a wide investigation concerning the capabilities of Cold Spray Technology for maintenance and repair of aeronautic frames and components. The project develops a New Industrial Portable Cold Spray Unit to extend the capabilities of in-situ maintenance and repair applications. The project will have a strong socio-economic impact by reducing scheduled maintenance requirements and by presenting a notable green character through re-usability, reduction of energy consumption, waste, toxic fumes and more.

Presentation at the 3rd International EASN Workshop in Aerostructures

An introductory overview of the CORSAIR project was realized on October 10th, during the 3rd EASN Workshop in Aerostructures. The workshop was held in Milan, Italy and was part of the celebratory activities of the 150th Anniversary of Politecnico di Milano.

2nd Progress Meeting

The 2nd Progress Meeting of CORSAIR took place on July 3rd-4rth, 2014, at the premises of TWI Technology Center Yorkshire in Sheffield, UK. Having completed the first year of the project, the consortium presented and discussed the ongoing progress, achieved results and future actions. After the meeting, the partners had the opportunity to visit the TWI labarotory and its hosted technologies.

Optimization of Cold Spray repairs on Al and Mg alloy components

During the spraying tests performed in the cold spray facility at VN, it was observed that the adaptation and installation of a specific water cooling of the nozzle (developed within WP3) at the ID gun equipped with a SiC nozzle, allowed the achievement of gas temperature up to 600°C without causing nozzle clogging, even after more than 20 h operations (20 min operations is the limit without this improvement), thus enabling the realization of a fully reliable process. A2024 (wrought alloy) and A357 (cast alloy) alloys have been tested up to now as the two more representative alloys for the realization of aircraft parts and gearbox & housings respectively. Concerning the coatings properties the achievement of cohesive strength up to 400 MPa (100 % of the base material strength) and bond strength higher than 50 MPa in case of A2024 on A2024 as reported in the graph below with a more than 100 % increase with respect to the traditional state-of-art process carried out at 350°C. Moreover deposition efficiency has been more than doubled. Further experiments to define the optimized deposition protocol with A2024 and A357 as well the realization of a complete plan of tests also with 7xxx alloys and Mg alloys are both planned and they will be carried out soon. The image presents a SiC nozzle and water cooling device provided by IMPACT, un-mounted (left) and mounted on the CS gun (right).

Determination of critical velocity

Two important parameters in cold spray deposition are the particle’s impact velocity, related to cold spray apparatus, deposition parameters and nozzle type, and the critical velocity, which is an intrinsic property of feedstock materials. No particle adhesion to the substrate occurs if the impact velocity is below the critical velocity. A computational fluid dynamic (CFD) model was used to estimate the particle impact velocity for given processing parameters. The model was also utilized as a tool for a new nozzle design based on optimum powder acceleration. A finite element simulation of powder particle impact onto the substrate was developed based on the CFD outputs. Furthermore, the critical velocity for Al2024 and Ti6Al4V was calculated using finite element simulation. The image presents a finite element simulation of Al2024 powder deformation onto the same substrate at impact velocity of 550 m/s. Severe deformation occurs at the rim of the powder with a material jet forming characteristic. Bonding in cold spray deposition begins in the same region.

Component Chart & Guidelines definition

The details of more than 25 different Al, Ti and Mg alloys components coming from 4 large industries, and the related defects to be repaired within the project, have been collected, described and included in a summarizing “Component Chart”. Starting from this Chart, a complete set of materials, powders, experiments, specimens’ type and use, characterization and quality control plan, as well as the guidelines to develop new models to describe the deposition process and equipment have been defined. The image above presents a specific specimen studied and designed to perform fatigue tests on cold sprayed material (axial defect geometry). The image below presents a coating sheet defined in order to provide a quick tool to describe the main mechanical and microstructural characteristics of a specific coating related to a specific deposition process.

Year 1 Progress – Project Summary

During the first year of development (01/06/2013-31/05/2014) activities included the collection and definition of industrial (end-user) requirements for the aeronautical parts to be repaired by Cold spray. Laboratory work also included the realization of simulation models to give the basis for technological developments, as well as the study of electro-chemical properties with respect to different alloys (Al, Mg, Ti). Finally, studies on the optimization of feedstock powders are being realized. An inner coating device has already been developed while work on the design of innovative nozzles and the mobile repairing system are progressing.

Presentation at the 2nd European Cold Spray Symposium

Represented by the Politecnico di Milano, the CORSAIR project will be briefly presented in EUCOSS 2014, involving key actors in the field of Cold Spray. The symposium will take place on May 26th in Paris, and it is organized by MINES ParisTech Graduate School.

Cold sprayed AA2024 coatings

The video presents adherence tests following ASTM 4541 performed onto cold sprayed AA2024 coatings using Automatic PosiTest® Pull-Off Adhesion Tester. This video is courtesy of URJC.

Cold Spray deposition of Al alloy

The video shows the deposition of an Al alloy for repairing a section of a Mg-based fan case frame. The camera focuses into the TWI cold spray laboratory to show other equipment including the waste particle collection unit, the gas compound, the powder feeder and control unit, and finishes with some coated samples. This video is courtesy of TWI.

CORSAIR Presentation

This video presentation provides a brief overview of the CORSAIR project’s concept, objectives, methodology and expected impact.

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