Thermal spray particulate presents unique challenges for in-plant dust collection. Regulations about particulate level emissions are becoming increasingly stringent. This paper will discuss the thermal spray environment and technologies that can be useful in the mitigation of airborne particulate. First, a discussion of basic filtration concepts - The many methods that are used to collect particulate (diffusion, inertial impaction, interception, and sieving) and an explanation of each with an understanding of when each methodology is used. We will also explore the properties of the typical thermal spray particulate - particle size analysis of typical resultant thermal overspray process dust including actual test data and scanning electron microscope photos. The structure of the filter media is vital to achieve superior filtration performance. A unique filter media technology for this application will be discussed, including media construction and characteristics of its use. Finally, the filter media must function within a system. A brief discussion of dust collection technology and the dust collection system will describe a solution to the problems of thermal spray particulate.

Alumina-titania coatings deposited by air plasma spraying (APS) are widely used to protect components against wear at low temperatures. It is known that microstructures formed by the post-laser remelting of as-sprayed coatings exhibit a densification but also numerous macrocracks due to the rapid cooling and thermal stresses. By using the laser-assisted air plasma spraying (LAAPS), the laser beam interacts simultaneously with the plasma torch in order to increase coating surface temperature and possibly superficially remelt the coating. As a result, the microstructure is partially densified and macrocracks, which are generally produced in the post-laser irradiation treatment, can be inhibited. In addition, this hybrid spraying can be done without the post-treatment of coating. In this paper, LAAPS was performed to improve the mechanical properties of Al 2 O 3 -13%TiO 2 coatings. The coating microstructure was characterized by SEM and X-ray diffraction. The mechanical characterization was done by hardness measurements, erosive wear tests and abrasion wear tests. Results showed that laser assistance may induce: (1) the disappearance of vertical and horizontal macrocracks due the laser irradiation in the coatings for a laser irradiation density lower than 34 W.mm-2, (2) an important decrease of the amount of microcracks in the deposited splats, (3) the partial transformation of the metastable γ-Al 2 O 3 phase in the equilibrium α-Al 2 O 3 phase, (4) a hardness increase of 11%, (5) an improvement of the erosive wear resistance by 12% and (6) an improvement of the abrasive wear resistance by 38%.

By use of up-to-date methods of gaseous detonation spraying it is possible to obtain coatings with wide range of thermal and kinetic energy of sprayed particles and their state (liquid, solid, semiliquid, with change of their chemical and phase composition duration of stay in impulse hot gaseous detonation jet, etc.). The philosophy of gas detonation sprayed coating structure and properties control include next basic methods: (1) change of values and ratio of thermal and kinetic energy of sprayed particles; (2) governing of thickness and sizes of single layers of coating (“coating spot“), D-Gun rate of fire, and relative velocity of moving of D-Gun and workpart; (3) change of dispersion and shape of powder particles; (4) regulation of thermal cycle of coating in process of spraying by use preliminary, concomitant or post spraying heating or cooling; (5) use of variable spraying modes for obtaining of individual layers and zones of coating (change of composition and flow rate of gases and powder, D-Gun fire rate, powder dispersion, distance of spraying, etc.); (6) settlement of ratio between percentage of amorphous, microcrystalline and crystalline phases, metastable and equilibrium phases by selection of rational conditions of spraying; (7) control of degree of physico-chemical transformations into powder particles (polymorphic transformations, dissociation, oxidation, interaction between components of composite powders, etc.), change of time of particles stay into gas products flow, composition and parameters of gaseous medium, etc.; (8) alloying of sprayed powders as for assurance of necessary properties of coatings as for improvement of their inclination to coating formation (oxidation resistance into high temperature gas flow, inclination of seizure, etc.); (9) use of composite powders; (10) spraying at mode with powder particles which have premelting temperature at time of coating formation; (11) treatment of sprayed coatings (thermal, thermo-chemical, thermo-mechanical, etc.); (12) control of coating macrostructure by successive deposition of layers, bands and spots of coatings with smooth or abrupt change of composition, deposition of discrete coatings; etc. Abstract only; no full-text paper available.

A high efficiency supersonic plasma spray system (HEPJet) was successfully developed with a maximum power of 80 kW and a maximum working gas flow of 6 m 3 /h. It can be used to spray metallic, carbide and oxide powders. The supersonic plasma spraying gun has a single-anode, internal feeding structure. The development of 80 kW inverse power supply with 20 kHz PWM IGBT circuit solved the problems of high output voltage, high output current and strong interference of high frequency. The production cost of this system is only equivalent to that of ordinary plasma systems. The average velocity of Al 2 O 3 particles in the plasma jet measured with a Oseir Spray Watch system reached 740m/s, and the coatings show high quality, good bonding strength and low porosity. The Co/WC coatings deposited by HEP Jet avoided the degradation from WC to W2C which should be attributed to the strong adjustability of the system for jet temperature and jet velocity.

An ozone condensation system is evaluated from the viewpoint of an ozone supplier for oxide thin film growth. Ozone is condensed by the adsorption method and its concentration is analyzed using the thermal decomposition method. The concentration of ozone exceeds 90 mol% and ozone is supplied for a sufficiently long time to grow oxide thin films. Investigation of the ozone decomposition rate demonstrates that ozone can be transferred into the film growth chamber without marked decomposition. The ozone concentration is also evaluated using a quadrupole mass analyzer and the accuracy of this method is compared with the results of the thermal decomposition method.

In this paper, metal matrix composite layers are produced by thermal spraying using cored aluminum wire. Two types of wire were produced, one containing mechanically alloyed Al and Cr 2 O 3 powders, the other, Al and AI 2 O 3 . The powders undergo self-propagating high temperature synthesis during the spraying process, which has a positive effect on coating properties such as bonding, cohesion, and wear resistance. Different spraying methods were used in the experiments, but satisfactory results were only achieved via atmospheric plasma spraying. Paper text in German.

This paper investigates the influence of plasma spraying parameters on the gas tightness and ionic conductivity of YSZ electrolyte layers in thin-film solid oxide fuel cells. Measurement data obtained from the layers are correlated with electrochemical test results, providing helpful information on how the performance of SOFC stacks can be improved. Paper includes a German-language abstract.