Project Code: 0902-10
Objectives
Utilise the spray particle diagnostics equipment and design of experiment approach to understand the relationship between process parameters and efficiency and coating characteristics and performance.
Evaluate various techniques for the measurement adhesive and cohesive coating strengths (tubular coating tensile (TCT) test and shear test) and novel adhesive materials for utilisation in these types tests.
Undertake a practical review of residual stress measurement techniques for coatings and identify the best approach for utilisation in future projects.
Utilise the above techniques in benchmarking and evaluation of the latest coating processes.
Provide coated samples for inclusion in project 0902-02 - Electrochemical testing of coatings.
Project Outline
The project will utilise the latest equipment and diagnostic tools to gain more understanding of the relationship between various coating processes, parameters and the properties, characteristics and performance of thermal and cold spray coatings. The project will use the SprayWatch particle diagnostic system to measure particle velocities and temperatures in flight, in conjunction with a design of experiment approach to gain improved understanding of the relationship between spraying parameters and coating characteristics and performance. It is proposed that several experiments will be undertaken with a range of common thermal and cold spray coatings to enable the results to be utilised in future SCP and joint industry programmes. Materials may include WC-CoCr (JP5000), Alumina (TopGun), Cu-Sn (Diamond Jet), ZrO2 (plasma) and Aluminium (cold spray). Should equipment be available, additional trials may be undertaken using the latest HVOF and arc spray equipment, where the spray watch system will be utilised for benchmarking systems selected from the JP8000 HVOF, closed loop arc spraying and cold spray processes. Coatings will be characterised in terms of microstructure, microhardness, adhesion and cohesion, surface roughness, deposit efficiency and wear and corrosion resistance where appropriate.
In addition to the above trials, the project will incorporate a practical review of measuring residual stresses in coatings. The work will assess the practicality of undertaking these measurements using the following methods:
- Hole drilling method
- Modified layer removal method
- Substrate curvature method
- X-ray diffraction (XRD) stress measurement method.
The results of these trials will aim to identify the most practical method for measuring residual stress which will then be utilised in the SprayWatch/DoE trials to help understand the implications between spraying parameters and coating characteristics. The results of this work will be of particular benefit for low adhesion coatings (eg on composites) where residual stresses may result in coating disbonds during service.
Further work will also be undertaken to evaluate measurement techniques for coating adhesive and cohesive strength including:
- Tubular coating tensile (TCT) test cohesive strength. Relationship of TCT to coating characteristics eg porosity (image analysis and gas absorption
- Evaluation of novel adhesives for tensile testing (to ASTM C633)
- Evaluation of the value of shear tests and relation of surface prep, process, material
Relevant Industry Sectors
Aerospace, Construction and Engineering, Electronics, Medical Oil and Gas, Power, Road Transport, Sensors