The Cold Spray coatings have been sprayed from binary eutectic alloy – Al-12%Si and from the complex composition iron-based alloy. The atomized Al-Si powder had close to microcrystalline (grain size around 1micron) structure, the Fe alloy powder had amorphous-nanocrystalline structure. Aluminum-based alloy was also sprayed with addition of up to 10% of aluminum oxide powder. The coating structure and properties have been investigated using optical microscopy, scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction, microcalorimetry, microhadness, tensile, bend, erosion and abrasion tests, and corrosion polarization tests. It has been shown that the Al-Si coatings have microcrystalline structure, and the Fe-based coating have amorphous-nanocrystalline structure similar but not identical to the feedstock powders. Cold Spray process has a specific mechanism to preserve the powders metastable structures. The coatings have enhanced hardness, wear and corrosion resistance. Abstract only; no full-text paper available.

This paper presents a comparative study of the microstructure, phase properties, hardness, and wear resistance of high-pressure HVOF sprayed coatings. The layers were produced by the JP-5000 method using WC12Co and WC17Co powders varying in size distribution and morphology. Spray parameters were statistically evaluated using a design-of-experiments approach in order to optimize wear resistance as well as deposition efficiency, carbide grain size, and degree of oxidation. Paper includes a German-language abstract.

A study was carried out on the corrosion resistance of the JP- 5000 coatings of Superalloy 625, WC-12%Co, WC-17%Co, WC-10%Co-4%Cr and Cr 3 C 2 -25NiCr materials and comparisons made with chrome plating. The coating corrosion resistance was evaluated using the standard salt fog test (ASTM B117) and also by submersion tests in 10% FeCl 3 solution (ASTM G48), in 10% HNO 3 and in 0.1M H 2 SO 4 + 0.2M HCl solutions. The coating corrosion mechanisms in relationship with the coating microstructure and phase constitutions are discussed. The test results show that the HP/HVOF coating corrosion resistance can be significantly improved through spray parameters and coating structure optimization. All coatings tested herein having optimum microstructure and phase constitutions have shown improved corrosion resistances in comparison with chrome plating.

In this paper, the morphology, the microstructure, the thermal stability ranges, the devitrification kinetics, and the hardness of amorphous detonation sprayed FeCrPC coatings are examined and compared with those of amorphous tapes of similar composition. Nanocoatings were made by heat treating the amorphous coatings. It is observed that thermal spraying (using the detonation gun method) produced coatings with an improved thermal stability of the amorphous component. Paper includes a German-language abstract.

In this paper, three goals are attacked, namely synthesis of nanostructured hydroxyapatite (HA) powder, obtaining HA phase constitution close to that of the bone hydroxyapatite, and preserving the initial HA composition and crystal structure in the sprayed coating. HA-aluminum composite coatings are produced using the cold gas dynamic spray method (CGDS). It is observed that the CGDS process enables the application of coatings without changing the phase composition of the HA, whereby the HA biocompatibility is retained. Paper includes a German-language abstract.

X ray diffraction and transmission electron microscopy studies and measurements of hardness and void content were carried out for WC-20% Co coatings produced by detonation flame spraying at various oxygen/acetylene ratios in the detonating gas mixture. It was demonstrated that successive transition from (WC+Co) to (W 2 C+Co 3 W 3 C) to (W+CO 7 W 6 ) occurs as the oxygen content in the mixture is increased, and that amorphous-nanocrystalline structures form in the coating. Two types of these hybrid structures were revealed, one including an amorphous metallic matrix containing precipitates of intermetallic nanocrystals, the other having an amorphous oxide matrix and nanocrystalline precipitates of CO 3 O 4 and WO 3 . The hybrid structures were shown to improve coating density and hardness.