A computational model of the effect of the tail end of the flame on the temperature of polymer coatings during thermal spraying is presented. The low thermal conductivity of polymers results in a substantial build up of temperature at the surface of the coating and large temperature gradients are developed throughout its thickness. This is particularly problematic for polymer deposition owing to their low decomposition temperatures. The model quantifies the heat transfer from the impinging flame and the in-coming feedstock particles to the coating and the subsequent heat flow into the substrate and surroundings. The work shows that the heat input from the in-coming particles can be neglected in first-order computations. The scanning action of the flame across the substrate is simulated and the temperature profiles within the coating and substrate are calculated. The predictions are consistent with the experimental measurements. The model shows that overheating of polymer coatings can readily occur during combustion flame spraying and indicates remedial measures.

The influences of process parameters on the microstructure of PEEK coatings deposited by flame spraying were analyzed by different physical and thermal methods, considering the density, the hardness and the Young's modulus. The cooling rate of the coating after spraying leads to large variations of the microstructure which evolves between the crystalline and amorphous states. Amorphous coatings exhibit less residual stress than semi-crystalline ones, which has an influence on the friction behavior.

Hydroxyapatite/polymer composite coatings of different volume ratios were produced using a Plastic Flame Spray (PFS) system. The intent of this processing is to obtain a coating with an optimal combination of biological and mechanical properties of these two materials for skeletal implants. The composite coatings were produced with a mechanical blend of EMMA and hydroxyapatite powder from a fluidized bed powder feeder. Characterization was conducted by scanning electron microscopy on the surface morphology, polished cross-sections and fracture surface morphology of the coatings. The bioactivity of the coatings was evaluated with a calcium ion meter, and the stress-strain behavior was investigated by tensile testing. The biological and mechanical properties were found to be related to the volume and the distribution of the hydroxyapatite in the polymer matrix.

Polymer ceramic composite coatings were applied by flame spraying on preheated steel substrates. Polyamide (PA 11, nylon) powder was blended with alumina (Al 2 O 3 ), aluminium nitride (AIN) or boron nitride (BN) powder with two different filler content to increase thermal conductivities of polymer coatings. Morphologies and particle sizes of polyamide and filler powders were examined by scanning electron microscope and laser scattering methods. Coating structures and thicknesses of composite coatings were studied by the polished cross sections. Thermal conductivities were measured by hot disc method. Thermal conductivities of polyamide coatings increased from 30 % up to few times by blending ceramic filler material on PA 11 powder. Structures of composite coatings were dense and filler materials were clearly observed in polyamide matrix.

The polyethylene terephtalate (PET) is widely utilized for high performance as a food and beverage container due to its excellent mechanical and chemical properties. The consumption of PET material is expected to increase more rapidly. Consequently, the recycling of waste PET is urgently needed to reduce environmental problems and economic costs. The purpose of this research is to endow waste PET materials with a new function by spraying of metal and ceramics such as Cu and TiO 2 . The recycled PET plate substrate for plasma spraying was prepared from waste PET bottles. It is found that Cu and TiO 2 powder could be sprayed on the surface of the recycled PET plate without heat damage and transformation of the substrate. In specific spray conditions, the implantation of melted Cu and TiO 2 particles, which retained their original shape, into the PET substrate was also observed and this is an unusual phenomenon in plasma spraying. In this research, the possibility of production of functional PET plates with electric conductivity and wear resistance was found by controlling the plasma spray conditions.

Polyetherether-ketone (PEEK) and Polyphenylene-sulfide (PPS) are high performance thermoplastics having high heat resistance and high corrosion resistance. Composite powders of PEEK / Alumina (Al 2 O 3 ) with different Al 2 O 3 content have been produced by four processes, which are Mixing (MX) process. Mechanical granulation (MG) process. Melting-crush (MC) process and Heating-granulation (HG) process. PEEK / Al 2 O 3 composite powders have been sprayed with High Velocity Air Fuel (HVAF) spray system. The microstructures of these composite coatings have been evaluated and the properties of these composite coatings have been investigated by the corrosion test, the adhesion test, the ACT-JP test and the abrasive wear test. It was recognized that all the composite coatings containing Al 2 O 3 powder have a good wear resistance. PPS / Al 2 O 3 composite powders have been sprayed with HVAF spray system onto substrate of various pre-heat temperature. It was recognized that the adhesion strength of the composite coatings increases with increasing pre-heat temperature of substrate.