Metallization of polymers and fiber-reinforced polymer composites is gaining attention due to the widespread application of these components in various industries, such as wind energy, aerospace, and automotive industries. Cold spray is a promising new technique to achieve the metallization of polymer and fiber-reinforced polymer composites. This work investigates the deposition mechanisms of polymer-coated metallic particles on polymer-based substrates by finite element analyses. Impact mechanics of PEEK-coated nickel particles impacting PEEK and carbon fiber-reinforced PEEK substrates are modeled. Results show the prominence of mechanical interlocking of metallic particles in the substrate, which occurs due to their entrapment inside the substrate, caused by the high energy impact-induced welding of scraped PEEK coating. The PEEK coating acts as a cushioning component, effectively mitigating the impact energy of the metallic component. The scraped PEEK coating also accumulates on the upper half of the particle, forming a cap welded to the substrate and sealing the metallic particle inside. It is observed that the depth of the carbon fiber mat in the substrate affects the mechanism and the success of deposition.

Biofouling has been persisting as a worldwide problem due to the difficulties in finding efficient environment-friendly antifouling coatings for long-term applications. Developing novel coatings with desired antifouling properties has been one of the research goals for surface coating community. Recently hydrogel coating was proposed to serve as antifouling layer, for it offers the advantages of the ease of incorporating green biocides, and resisting attachment of microorganisms by its soft surface. Yet poor adhesion of the hydrogel on steel surfaces is a big concern. In this study, porous matrix aluminum coatings were fabricated by cored wire arc spray, and the sizes of the pores in the aluminum (Al) coatings were controlled by altering the size of the cored powder of sodium chloride. Silicone hydrogel was further deposited on the porous coating. The hydrogel penetrated into the open pores of the porous Al coatings, and the porous Al structure significantly enhanced the adhesion of the hydrogel. In addition, hydrogel coating exhibited very encouraging antifouling properties.

In subzero conditions, atmospheric ice naturally accretes on surfaces in outdoor environments. This accretion can compromise the operational performance of several industrial applications, such as wind turbines, power lines, aviation, and maritime transport. To effectively prevent icing problems, the development of durable icephobic coating solutions is strongly needed. Here, the durability of lubricated icephobic coatings was studied under repeated icing/deicing cycles. Lubricated coatings were produced in one-step by flame spraying with hybrid feedstock injection. The coating icephobicity was investigated by accreting ice from supercooled microdroplets using an icing wind tunnel. The ice adhesion strength was evaluated by a centrifugal ice adhesion tester. The icing performance was investigated over four icing/deicing cycles. Surface properties of coatings, such as morphology, topography, chemical composition and wettability, were analyzed before and after the cycles. The results showed an increase in ice adhesion over the cycles, while a stable icephobic behaviour was retained for one selected coating. Moreover, consecutive ice detachment caused a surface roughness increase. This promotes the formation of mechanical interlocking with ice, thus justifying the increased ice adhesion. Finally, the coating hydrophobicity mainly decreased as a consequence of the damaged surface topography. In summary, lubricated coatings retained a good icephobic level after the cycles, thus demonstrating their potential for icephobic applications.

In this study, icephobic polymer coatings were produced by flame spraying using different process parameters. Process optimization for low-density polyethylene (LDPE) coatings was achieved through design of experiments. The most icephobic coating was produced at a traverse speed of 900 mm/sec and a spraying distance of 250 mm. Although surface roughness affected ice adhesion, thermal effects proved to be the main factor influencing the performance of the coating. The higher the processing temperature, the smoother the surface and the greater the polymer degradation. It is also shown that coating degradation can be caused during post heating steps with similar consequences in the ice-shedding performance of the LDPE coatings.

This paper presents the results of research, testing, and comparison of polyamide (nylon) 11 coatings made by flame spraying and electrostatic spraying followed by oven or induction heating. It discusses the advantages and disadvantages of each process and the coating properties that can be achieved.

Polypropylene (PP) was flame sprayed onto rough mild steel substrates at room temperature (RT) that was preheated at 70 °C, 120 °C, and 170 °C. Single solidified droplets (splats) were collected and analysed to understand how processing variables influenced the thermal spray coating characteristics. The splat morphology was characterized in detail using optical and scanning electron microscopy (SEM). The splats exhibited a disk-like shape with a large central viscous core and a fully melted wide rim with a thin edge. The splat size increased with increasing substrate temperature. A unique flat microstructure was observed on the surface of the splat deposited onto the RT substrate, whereas a flowing pattern appeared on the splat surfaces deposited onto the preheated substrates and the pattern increased by increasing the substrate temperature. The results of this study revealed improved splat-substrate adhesion by heating the substrate from RT to 170 °C. On the basis of the result, the influence of substrate parameters on splat morphologies was employed to establish a relationship between the microstructural characteristics and processing variables of flame sprayed polymeric coatings.

This research aims at introducing new biodegradable/non-biodegradable materials (biopolymers) to the existing Hydroxyapatite (HA)-titanium combination or as a single coating in order to overcome some of the limitations of HA coatings. Biopolymers can act as drug carriers for a localised drug release following implantation; they can also have a structural role by improving the mechanical performance of implants at the bone –implant interface. The proposed materials consisted of biodegradable and non-biodegradable polymers widely used as drug delivery systems: polymethylmethacrylate and polyhydroxybutyrate 98%/ polyhydroxyvalerate 2%. The method used to apply the polymeric powders was oxygen/acetylene flame spraying, due to its superior mechanical advantages over other techniques. Screening tests were used to determine the suitable range of spraying parameters, followed by optimisation to understand of the effects of spraying parameters on coating characteristics (thickness, roughness, adhesion, wettability), in order to obtain an optimal coating design. The polymers were sprayed onto bare titanium substrates. FTIR results showed that the coatings underwent little chemical degradation. Biocompatibility tests showed that cells proliferated well on flame sprayed polymer coatings, which confirms that the coating technique used did not affect the biological performance of the material.

A new coating process called polymer thermal spraying (PTS) was recently developed to accommodate the deposition of heat sensitive polymeric materials over a broad range of substrates. The novel process uses an electro-resistive element to heat the main process gas, which could be air, any pure gas, or gas mixture. This paper describes the process and presents three case studies in which it is used to produce blast mitigation coatings for civil structures, super-hydrophobic coatings for corrosion protection, and flame resistant polyimide syntactic foams for thermal insulation.

This study analyzes the effects of laser remelting on the morphological structure and adherence of flame-sprayed PEEK coatings on stainless steel. Different types of lasers were used with wavelengths of 1.064 mm (Nd:YAG), 10.6 mm (CO 2 ), and 0.88 mm (diode). It was found that the longer the wavelength, the more compact the coating, but the less well-adhered. By making adjustments to compensate for the wavelength-dependent absorption coefficient of PEEK, both coating properties were improved.

The application of ceramic die coatings on tool steel dies in the casting industry has been common practice for many decades. The main function of these coatings is to provide a thermal barrier to prevent premature solidification during die filling, and protect the tool steel die from the effects of molten metal during casting with aluminium alloys. Although these coatings provide good insulation they are fragile and require on-going in-situ maintenance by machine operators. These inherent poor qualities makes the die casting process difficult to control and to maintain cast product quality because the solidification pattern and porosity changes and leads to increased cast product rejects. To overcome the limitations a novel die coat has been developed for the light metal casting industry utilising thermal spraying of co-deposited MgZrO 2 and polymer particles. The coating is then thermally treated to reveal a fine network of porosity that has been found by heat transfer coefficient testing to enhance the thermal properties and overall coating durability during casting. This paper describes the porosity control system which was used to tailor the heat transfer coefficient of co-deposited MgZrO 2 and polymer coatings and compare them with the heat transfer coefficient of commercially available die coats. The inherent porosity and the overall coating thickness were found to have a large effect on the heat transfer coefficient. Results of industrial trials are also presented and show that co-deposited MgZrO 2 and polymer coatings provide considerable improvements to productivity and enhanced coating life in Gravity and Low Pressure Die casting of aluminium alloys.

The fracture behavior of polymer coatings fabricated by low temperature high velocity air fuel (LTHVAF) spray was investigated. It was shown that the coatings were dense and had a mean bonding strength of 13.5 MPa. During the tensile stress process, the fracture occurred in the interior of the coatings, which indicates that the cohesive strength within coatings is less than the bonding strength between the coatings and substrate. A significant amount of crazing and honeycombed holes existed in the fracture surface. Under a tensile stress, cracks initiated at porous defects in the coatings. Dispersed particles interrupted the crack expansion, and caused a change in direction of crack propagation.

The high velocity oxy-fuel (HVOF) combustion spray technique has been shown previously to be an excellent solution for depositing crystalline matrix nano-reinforced polymer coatings. Dense polymer coatings can be produced by controlling both the particle dwell time in the HVOF jet and through substrate thermal management. In composite materials, it is often desirable to incorporate the maximum amount of reinforcing material into the polymer matrix to achieve optimum mechanical properties. The experiments described here were performed to determine the maximum amount of different scales of silica particles that could be incorporated into a nylon 11 matrix and the time required to do so. Ashing results indicated a maximum amount of silica that can be incorporated. Also, the maximum level of silica incorporation occurs in a shorter time than previously believed. Microscopy, however, indicated that other physical changes continued to occur within the powders when ball milling was allowed to continue beyond this time.

Several polymeric coatings, including flame sprayed polyethylene (PE), were evaluated for use in parts of natural gas pipelines. The components of interest were for instance large valves, T-joints, weld joints of pipes and pipe bends. More than 30 different coatings were selected to laboratory scale testing and evaluation. After first preliminary tests, the most potential coatings were selected further for more detailed and long term laboratory scale studies. After these tests were finished, one coating concept, i.e. fusion bonded epoxy (FBE) + flame sprayed PE, was prepared on a small natural gas valve body for demonstration purposes. Besides this coating concept, also some other coatings, e.g. liquid epoxy + flame sprayed PE and some polyurethane coatings were found to be potential coatings for the application. The test methods and results are presented in this paper.

The high velocity oxy-fuel (HVOF) combustion spray technique has been shown previously to be an excellent solution for depositing crystalline matrix nano-reinforced polymer coatings [1]. Dense polymer coatings can be produced by HVOF combustion spraying by controlling particle dwell time in the jet and through substrate thermal management. Use of an amorphous matrix material, polycarbonate, will enable the role of matrix crystallinity on the structure and properties of thermally sprayed polymer composite coatings to be separated from effects resulting from the reinforcing phase. An amorphous, commercial polycarbonate resin with a broad particle size distribution of irregular particle morphology has been successfully deposited. Results from optical microscopy, X-ray diffraction, scratch and density measurements are presented. The influence of variations in process parameters such as spray distance, nozzle length, chiller temperature, fuel: oxygen ratio, and total gas flow rate on coating microstructure are presented.

This paper aims to fabricate wear resistant composite coatings on light metal substrates which also exhibit low friction coefficients. It demonstrates that combined ceramic polymer coating systems are a powerful concept for industrial applications where high wear resistance, creep resistance and compressive strength as well as low friction coefficients are required. The results show that, under the specific experimental conditions used, the titanium dioxide layer in connection with the applied lubricant lacquer showed better performance than the mixed aluminum oxide/titanium dioxide layers. Paper includes a German-language abstract.

Electrostatic fluidized bed spraying is a coating process that is often used for coating plastic. A novel flame spray technology with a controlled atmosphere was developed by Air Liquide in order to realize coatings with thermoplastics as well as composite coatings such as plastic/ceramic or plastic/metal. This technology expands the scope of the applications of plastic coatings especially for all types of shapes and materials as well as for on-site coating. Two types of powder, namely Rilsan and Gotalene were used in this study. The tests were carried out by HTI, which is Air Liquide's partner in the development of such applications. After introducing the principle of this process, this paper presents and discusses the coating process and the properties of such coatings. Then the advantages and limitations of the process are highlighted. Paper includes a German-language abstract.

Fiber-reinforced polymer composites are an important class of structural materials, offering high strength-to-weight ratios and high rigidities. For many applications, however, their wear resistance is less than desirable. Wear-resistant thermal spray coatings have the potential to improve the surface properties of fiber-reinforced polymer composites, although some require the application of a bond coat to achieve sufficient adhesion. The present study was conducted to find acceptable bond coat materials and compare their performance. Materials such as polyamides, polyimides, polyether-ether-ketone, or simply aluminum or nickel were found to be suitable bond coats for many composite substrates.

The last decade has seen a rapid increase in the use of Thermally Sprayed Coatings for Oil and Gas production applications. In particular, since 1982 the Offshore Oil and Gas Industry has considered Thermally Sprayed Aluminum (TSA) for protection of steel structures in the splash zone and other areas in the marine environment. Experience to date has indicated that when TSA is properly applied with a specific sealer system a service life in excess of 30 years with zero maintenance is possible. This produces a corresponding reduction in life cycle costs. Other coating systems such as nickel-based alloys, ceramics and thermoplastics are also finding useful applications. This paper discusses recent advances in thermal spraying technology and current and future applications in the Oil and Gas Industry. This is illustrated with reference to several projects and details on life cycle costs. In particular, thermal spraying of pressure vessels, risers, pipelines and structural components are detailed.

Polyphenylene-sulphide (PPS) and polyphenyletheretherketone (PEEK) have high heat and corrosion-resistant performance. Thermal sprayed coatings of PPS and PEEK have been produced by the HVAF spray system. The molecular structures of these coatings have been analyzed by Fourier Transform Infrared Spectrophotometer (FT-IR) and Differential Scanning Calorimeter (DSC). The microstructures of cross-section and surfaces of these coatings have been observed. The formation mechanism of these coatings has been estimated as follows; (1) PPS and PEEK powders are melted and oxidized during thermal spraying. However, the amount of coating oxidation is very small, so that high anti-corrosion performance of sprayed coatings is obtained. (2) These coatings have some pores including the incomplete melting particles. However, it is estimated that these pores are closed-pores.

The mechanical properties of EMAA copolymer are dependent upon the thermal spray processing parameters. The parameters determine coating temperatures which, in turn, affects the microstructure. If the deposition temperature is too low, (104 °C for PFl 13 and 160 °C for PFl 11) coatings have low strengths and low energy to break values. Increased coating temperatures allow the particles to fully coalesce resulting in maximized strength and elongation to break. However, at 271 °C, PFl 11 had visible porosity which decreased both strength and elastic modulus. Pigment acts as reinforcement in the sense that the modulus increased but the elongation to break decreased, thus reducing the energy to break. Water quenching reduces the elastic modulus and yield strength, but increases the elongation to break for both EMAA formulations. The mechanical properties of post consumer commingled plastic and PCCP / EMMA blends improved if the recycled plastic was pre-processed by melt-compounding. Melt compounding increased the strength and toughness by improving the compatibility among the various polymer constituents. The addition of PCCP increases the modulus and yield strength of ethylene methaciylic acid copolymer.