Polymer metallization using cold spray method, due to low process temperature, is a potential candidate to form electrically conducting polymers as well as composites and improve the mechanical properties of their surface (abrasion, corrosion, etc.). Low Pressure Cold Sprayed copper coatings on PEEK (Poly-Ether-Ether-Ketone) based composites reinforced by carbon fibers have been investigated. Cold Spraying involves high erosion on composite materials due to solid state and high velocity particles thus a new way has been developed. Based on the elastic behaviors of organic materials, pure PEEK matrix has been added on the composite surface to behave as an interfacial layer between the composite and the coating. Optimization of the LPCS parameters has then been carried out using a careful choice of powder size distribution in order to avoid substrate destruction, erosion and delamination of the coating. Consequently, dense thick copper coatings have been obtained and analyzed in terms of microstructure implementing SEM observations. Finally, electric measurements have been performed in order to check the efficient metallization of the composites. A new way for metallic coating on organic composites using Low Pressure Cold Spraying is then demonstrated.

This study analyzes the mechanical properties of aluminum alloy substrates, in particular, changes in flexural behavior of laser-textured surfaces. Bending tests are conducted on samples treated by laser texturing and by conventional methods such as chemical degreasing and sandblasting. A comparison of flexural strengths caused by the different surface pre-treatments method is presented.

Surface state plays an important role in particle bonding and formation of the first layer of coatings in thermal spraying. From a chemical aspect as well as a mechanical point of view, in all cases, the substrate surface needs to be optimized to promote the adhesion of the sprayed particles and then the coating. In order to control such parameters, several works have been conducted to avoid drawbacks on sensitive materials. This study aims at developing a laser surface texturation before the spraying process to improve the coating adherence. According to the laser parameters, different surface morphologies (hole diameters, surface roughness, hole depth, etc.) can be developed. The surface material morphologies were characterised by SEM and bond strength was evaluated through ASTM C633 pull tests. This approach has been applied on the system Al 2017 / NiAl and demonstrates a high influence of the laser treatment. However, the thermal effect induced during the laser-matter interaction has to be controlled to avoid negative effects of the substrate properties particularly tribological properties. In this case, a study of the effect of the conventional processes and texturing process on the fatigue properties of substrate were studied.

In this work, a LCA based on Eco-indicator 99 methodology was used to compare the environmental impacts and benefits of thermal spraying (including APS, HVOF, Flame and Cold Spray) carried out with materials which could be used in application to resist against wear and/or corrosion. The comparison was carried out using the SimaPro 7.2 software, and it was focused on all stages necessary to build the coating, i.e. extraction of raw materials, production of powder, transport, surface preparation, thermal spray operating, until the end of life, as well as emissions (solid, liquid and gaseous) at each stage of a process. As a major result, it appears that the lifetime of the coatings plays a high role. If a coating needs to be regularly replaced or if failure of the coating decreases the lifetime of the component, this almost impact on the LCA. Moreover, there is an influence on the nature of the resources used to build the coating, as well as on the end of life strategies.

The aim of this paper is to propose a LCA comparison of different surface preparation processes (degreasing + sandblasting, laser ablation and laser texturing) which tend to be used before thermal spray. The SimaPro software was used and the needs of materials, the energy and the corresponding emissions of each process, were converted to impact scores on human health, ecosystems, and resource conservation (fossil and mineral resources) by mean of the Eco-Indicator-99 method. Laser pretreatments processes present a very good environmental behaviour in comparison with degreasing + sandblasting.

This paper deals with coating alternatives to hard chromium plating. Indeed, thermal spraying is already used in industry, but results are not always satisfactory for reasons of porosity and microstructures. In this study, atmospheric plasma spraying (APS) and in situ laser irradiation by diode laser processes were combined to modify the structural characteristics of thick NiCrBSi alloy layers. The microstructure evolution was studied and results show that in situ laser remelting induces the growth of a dendritic structure which strongly decreases the porosity of as-sprayed coatings and increases the adhesion on the substrate. Moreover, no phase transition after laser treatment is observed. At least, a mechanical investigation demonstrates that the combination between the plasma spraying and in situ melting with a diode laser can result in the improvement of mechanical properties. The hybrid process appears to be a possible alternative to hard chromium plating, in order to protect mechanical parts, because of the good mechanical behaviour of NiCrBSi layer. Moreover, the increase of the laser incident power causes an increase of the mean contact pressure, along with coatings hardness.

Pressure to identify alternatives to hard chromium electroplating has increased these few last years, related to environmental requirements, because of the use of hexavalent chromium, a highly toxic substance. The plasma spray technique allows the formation of thick coatings which present moderate adhesion to the substrate and show porosity and formation of oxide interlayers, which impairs to obtain full benefits of the coatings properties. In this sense, a treatment can be necessary to improve the properties of these coatings. In this paper, the effect of an in situ laser melting treatment of NiCrBSi coatings, deposited by plasma spraying was investigated. It is demonstrated by a Life Cycle Assessment (LCA) that this process is clean. Moreover, the corrosion resistance of as-sprayed and in situ remelted layers was evaluated by potentiodynamic polarization curves. The corrosion resistance was increased because of the finer structure and higher densities of the coatings, nevertheless, corrosion mechanisms occurring in all cases are different.

Surface treatments are often necessary in thermal spraying to modify the surface properties of materials and then to improve the coating adherence. Several techniques exist. Among them, conventional techniques such as sandblasting, chemical degreasing and some others like high pressure water jet or laser ablation can be implemented. However, whatever the results, some drawbacks can always be listed according to the materials considered (sensitive materials, low adherence level). By this way, new techniques have to be developed. Considering the laser technology, some new treatments can be particularly suitable for surface modifications. Based on the printing technology, laser texturing implementing fiber laser technique combined with a scanner permits to engrave quickly uniform holes on the surface. Applied as a surface treatment before spraying step, the potential of such technique is particularly observed in this study. According to the laser parameters, several points can be analysed such as size (diameter and depth) and the distance between each holes. After surface characterizations by SEM observations and roughness measurements, adhesion tests were then implemented. Considering NiAl coatings sprayed on textured aluminium alloy substrates, some very interesting adherence results (55 MPa) were measured in comparison to the conventional treatments (45 MPa after degreasing and sandblasting) as well as laser ablation technique (34 MPa).

The aim of this study is to propose coatings that could potentially replace hard chromium as a means of corrosion and wear protection. Two NiCrBSi coatings are evaluated, one produced by laser cladding, the other by atmospheric plasma spraying with a post-laser treatment. Although laser-clad NiCrBSi exhibits the best technical properties, the APS coatings were found to be more environmentally justifiable based on the use of life cycle assessment (LCA) software.

The sliding wear behavior of thermally sprayed aluminum oxide is fairly well studied, but little is known about its fretting behavior under cyclic tribological loads. This study investigates the fretting behavior of plasma sprayed alumina and the related influence of TiO 2 additions. Three Al 2 O 3 -TiO 2 composites are sprayed on steel substrates using commercial powders and the resulting layers are characterized based on hardness, porosity, surface morphology, phase composition, and fretting behavior. The results of the study show that TiO 2 additions reduce microhardness and increase coating toughness. The effect of TiO 2 on fretting behavior and surface wear is assessed after 10, 50, 100, 250, and 500 load cycles based on SEM imaging, friction measurements, and debris formation. Observations and test results are presented and discussed. Paper includes a German-language abstract.

Reducing operating clearance between the HP turbine and shroud is a means often used by engine manufacturers to improve the efficiency of new generation gas turbines. This, in turn, requires the development and use of clearance control coatings to minimize the effects of degradation and wear associated with rubbing. In this study, the authors assess two coating systems: VPS NiCoCrAlYTa coatings for blade tips and plasma-sprayed MCrAlY, a potential abradable coating. In order to understand the wear mechanisms of these systems, block-on-ring and fretting tests were conducted and the relationship between microstructure and wear was examined. The results were then compared to those of rub tests performed with real engine components.