Cold Spray Technology

NLR Vision on Cold Spray

What is cold spray?
Cold spray is a relatively new technology belonging to the thermal spray technologies. However, it is actually a solid-state process in which the powder particles are accelerated to supersonic velocities and impacted upon colliding with the substrate to be coated.

Thanks to its low thermal input to the substrate, cold spray is suitable for temperature- or oxidation sensitive materials. Also phase changes and grain growth of the substrate do not occur. This is extremely beneficial when the sprayed object has undergone heat treatments to increase hardness, strength, or toughness, which would degrade when the thermal input to the substrate becomes too high. Furthermore, the other heat related issues in other, hot, thermal spray methods, such as thermal residual stresses or thermal shrinkage pose no problem in cold spray.

What are the applications?
Due to compressive stresses being formed during the plastic deformation of the powder particles, thick coatings, or material deposits, can be formed. Cold spray is therefore suitable to repair all kinds of metal parts. An example from the aerospace sector is found in magnesium gear boxes housings in helicopters. They corrode as a result of damaged coatings or severe environmental conditions, with oil leakage as a result. Without cold spray, scrapping of these housings was often necessary. Geometric restoration of these damages with cold spray reduces costs and the environmental footprint. Similar applications include restoration of moulds, die casts, or automotive components. Since large thickness deposits are possible, cold spray is also used as an additive manufacturing technique. It can be used to form completely new parts or to add features to existing objects. Compared to the longer existing additive manufacturing techniques, cold spray based manufacturing allows for a higher build rate. As a result, large(r) parts can be produced at relatively low costs.

The freedom of material selection makes the amount of applications immense. The range of metals that can be processed include steel, aluminium, copper, bronze, magnesium and many others including a large number of their alloys. Besides metals, also polymers, ceramics or metal matrix composites such as carbide based blends (e.g. WC-Co or CrC-Ni) can be processed. All these materials allow for application of all kinds of functional coatings. Think of improvement of corrosion resistance, improved wear resistance, or other tribological properties that come with the application of a dedicated spray material.

Joint research programme with NLR
In order for cold spray to form a well-adhering, high quality coating or product, it is necessary to know the effect of all material and process variables involved. For each specific application, machine settings and process conditions will differ. Therefore, Royal NLR aims to build up cold spray experience and knowledge together with partners from industry, SMEs, universities or research institutes. To this end, a 4-year joint research project will be set up in which participants can bring in their technological issues and research topics. Participating companies are encouraged to come up with a demonstrator to be developed.

The programme format will be a Public Private Partnership, in which every company contributes approximately 30k€ each year. NLR will contribute substantially (in the order of 25-30% of the total budget) and use TKI as a multiplier for the project budget. More information on this topic can be found in the PPP section on this website.

Based on the responses, NLR will host a meeting to present the joint research programme (PPP) on Cold Spray. Interested companies are invited to fill in the questionnaire to indicate their interests and research topics for the programme. More information can be found in the Cold Spray PPP gathering section on this website.

NLR Background

NLR has decades of experience with aircraft structures, materials, and maintenance. Thanks to its wide field of applications, cold spray is a technology that fits into many business areas, including those of NLR. For example, cold spray finds applications in Additive Manufacturing. NLR started with metal additive manufacturing in 2012 with Powder Bed Fusion technology. Since then, the additive manufacturing team became what we now know as the Metal Additive Manufacturing Technology Centre (MAMTeC) which recently expanded its technologies with the purchase of a Directed Energy Deposition machine. NLR cooperates with industry, small and medium-sized enterprises, universities, and other research institutes in order to master the processes and to be able to produce parts with a constant and high quality at competitive prices.

Another obvious field of cold spray application is in maintenance. NLR is active in MRO, in the sense of technical solutions and with the certification trajectories involved with these solutions. NLR has many years of experience with designing repair solutions for worn or damaged components or coatings, and damages as a result of corrosion. The facilities, such as a metallurgical laboratory including SEM, are crucial to perform research, inspect parts and repaired components, including cold spray coatings or components.

Cold Spray PPP gathering

Royal NLR invites you to the attend the presentation of our joint research programme on Cold Spray. The presentation will be held on Thursday, 19th of November 2020 from 10:00 to 12:30 and will take place online via BigBlueButton. This gathering is open to industry, SME’s, universities and other research institutes that are interested in participating in the PPP on cold spray. After registering through this website, you will receive a confirmation of your registration. Prior to the meeting you will receive an e-mail with a link to the BigBlueButton meeting room.

Research topics will be based on the interest and application fields of the programme participants. Therefore, we kindly ask you to fill in our questionnaire to indicate the topics in which you are interested. The responses to our questionnaire will be treated confidentially.

Programme 10:00 – 12:30

10:00 Welcome by Royal NLR

10:15 Presentation of project proposal including finance, IP, PPP format and TKI instrument

11:30 Questions

11:45 Discussion in small groups (4P / Break-up room)

12:15 Central discussion and wrap up

12:30 Closing

We look forward to an interactive meeting with participants from different fields of industry!

Please register here.


Due to Covid-19, the presentation of the cold spray programme will take place online via BigBlueButton. After registering through this website, you will receive an email with a link to the BigBlueButton meeting room.

Public – Private – Partnership

The project will be setup as a Public Private Partnership programme. A Public Private Partnership programme is a cooperation of private companies and research institutes like Royal NLR. By doing so we can use the PPP Program Allowance for collaboration projects. The PPP Program Allowance budget is based upon the height of industry private investments in collaboration projects. So for every euro NLR receives from an industry partner in support to this project, NLR can add public funding to the same project, making it more value for money. NLR performs the work, companies support the project for instance via progress meetings and reviews.

The PPP Program Allowance is a subsidy instrument of the Dutch Ministry of Economic Affairs and Climate Policy to stimulate private-public partnerships. The collaboration projects may consist of non-economic activities, fundamental research, industrial research and experimental development. In these collaboration projects industry and research institutes work together.

The legal framework of these PPP programmes is the European Framework for State aid for research and development and innovation (2014 C 198 01) – Indirect State aid to undertakings through public funded research and knowledge dissemination organisations and research infrastructures. Therefore the PPP agreement will be based on this regulation.