This article discusses the influence of refrigerants on the cooling of thermal spray equipment. The discussion covers the cooling requirement for thermal spray equipment, basic cooling systems, improvement and adaptation of refrigerants, challenges for manufacturers and users of cooling technology, and ways to address the challenges.

Machines and other equipment that are used in industry are generally long-term investments. Once invested, the machines usually run for several decades until a technical reinvestment is necessary. Nowadays, the 4th industrial revolution is taking place and digitalization is omnipresent. Big Data, Internet of Things (IoT) and Artificial Intelligence (AI) are just some of the technological innovations that are shaping the future right now. These innovations do not work with the manually driven equipment that has been invested some years ago because they are all based on data – and these (partly) manually operated equipment don´t produce data or they don´t collect it properly. In order to produce and collect data, the manually working machines have to be replaced – or retrofitted! voestalpine Stahl GmbH and its technical service and maintenance department (TSM, furthermore short voestalpine) decided to retrofit the existing equipment based on technological, economical as well as sustainability reasons. The approach, advantages and limitations are displayed here.

The advantages of thermal spray technology open an increasing number of applications in several fields. However, it has to be considered that thermal spray processes contain several, partly substantial potentials of danger. As other machinery in Europe, thermal spray equipment is subject to essential health and safety requirements. This paper lists the necessary steps for the manufacturer to develop and to bring into market machinery and parts of machinery that are in conformity with the CE requirements. “CE” represents “Communauté Européenne”, the French term for the European Community. The directives, codes and legal basics, the procedure of risk assessment, the requirements to the technical documentation as well as the conditions regarding declaration and marking are discussed under the point of view of thermal spray. Some sections treat the status of modified and reconditioned machinery, the duties of users of thermal spray equipment as well as similarities and differences in the requirements in Europe to other markets.

Thermal spray coatings are used for a broad range of purposes in the semiconductor equipment industry. A primary use of thermal spray coatings for thin film applications is to provide surfaces on process chamber components that promote particle reduction and contamination control during chamber operations. Coatings are also used to provide the desired dielectric properties for critical components such as electrostatic chucks (ESC) and heater pedestals; to prove chemical and corrosion-resistance for process kit components and showerheads; as well as serving a wide range of other purposes. This paper reviews future needs for thermal spray coatings in semiconductor equipment and identifies some of today’s coating challenges. Areas discussed include coating design considerations; chemical, corrosion and plasma erosion issues influencing the selection of materials, coatings and processes. Brief discussion will be provided for future anticipated needs in materials, coatings, processing and the manufacture of thermal spray coatings for such applications.

Thermal spray metallic coatings are used for a range of applications in the semiconductor equipment industry including applications from particle reduction to precious metal reclaim in chamber operations during thin film deposition. Thermal spray coatings assist in reducing part costs, increasing product performance and lifetimes, and reducing chamber maintenance. The processing parameters in two-wire arc spraying of aluminum are traditionally used to provide a range of coating properties in industry from dense coatings for corrosion control applications- to rough texture coatings for anti-slip applications. Thus, the two-wire arc processing parameters selected for use for semiconductor applications are critical for surviving the semiconductor processing environment and increasing product performance. Important two wire processing parameters include current, voltage, atomizing air pressure, and stand-off distance between the gun and target (sprayed part). Secondary processing parameters including robotic traverse rate, air cooling, part manipulation (turntable speed, etc.) and others. Further, the specifics of the two-wire arc gun design (make/model), nozzle diameter, air caps, and wire diameter are also important variables. Current and voltage are important parameters for generating the electric arc for melting the aluminum wire. An optimum processing window exists for the range of current and voltage used for producing the aluminum coatings. The atomizing air pressure also has an optimum range for atomizing the molten aluminum produced from the electric arc. A range of atomizing air pressures are used to produce a range of coatings from dense to rougher textured coatings. Higher operating current increases the quantity of molten producing the coatings, and the lower operating current reduces the spray rates of the aluminum to be atomized. This paper examines the two-wire arc parameters producing aluminum coatings. Two-wire arc parameters to be examined include current, voltage, atomizing air pressure and stand-off distance varied to produce coatings. The coating produced from these parameter changes will be investigated in terms of microstructure and mechanical properties. The microstructural investigation will involve porosity analysis. Mechanical property testing will include tensile-adhesion bond strength. The surface roughness will also be investigated

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.

With high speed development of modern industry, the research and application of thermal spray technology made more progresses, the thermal spraying technology was applied more and more widely in industry fields. At the same time, the people pay more and more attention to the development of thermal spraying industry. In the paper, the development trends of thermal spray were presented on the basis of analyzing the research and application of thermal spraying technology. Spray particle velocity is developed to high velocity. Thermal spraying equipments is developed to multi-functional and accuracy and save energy and high efficiency. Spraying materials is developed to nano structured material, preparation of Nano Structured Coatings is one of directions of development of thermal spray. Thermal Spray has more widespread application prospect in aerospace, environmental protection and biological implant fields.

The author carried out in 2003 a multiclient survey and research covering thermal spraying industry in China. This work mainly focus on the productive level and scale of thermal spraying equipment and materials, application and coating job shop, R&D in universities and institutes as well as the develop trends of thermal spraying industry in China. This presentation intends to provide general pictures on thermal spraying industry in China, by offering data and analysis, forecasts the future of thermal spraying in China.

Within the framework of a scientific collaboration between the University of Limoges, France and the State University of New York, Stony Brook, USA, a joint work has been conducted on microstructure development and properties of plasma-sprayed molybdenum coatings. This first part of the work is devoted to the study of the effect of substrate nature and temperature on splat cooling, solidification and crystalline structure. They were investigated by means of a heat transfer model in the splat and the substrate, and the observation of splats by a scanning electron microscope and an atomic force microscope. The model takes into account melt undercooling, nucleation and crystal growth, as also a possible melting and re-solidification of the substrate. It has the capability to predict the grain size distribution under assumptions that the quality of contact between the splat and the underlying layer is uniform, nucleation takes place only on the substrate surface, crystal grains grow perpendicular to the substrate surface and no grain coalescence occurs during crystal growth.

This is part II of the two part paper based on international collaboration between the University of Limoges, France and the State University of New York, Stony Brook, USA, aimed at fundamental understanding the relationship between processing condition and microstructure development and properties of thermally sprayed materials. In this study, the effects of deposition temperature on the microstructure and properties development of molybdenum coating was investigated. It is found that with the increase of steel substrate temperature, the molybdenum splat morphology changes from fragmented to more contiguous disk-like shape. The splats on molybdenum substrate show predominantly disk shape. With the increase in deposition temperature, the coating exhibits better lamellar structure with less interlayer pores and debris. The fracture characteristics changes gradually from interlamellar to trans-lamellar and, thermal conductivity is enhanced. Higher deposition temperature improves dramatically the adhesion and bonding of the splats, therefore the physical and mechanical properties of coatings.

The conditions of particle injection into the side of plasma jets play an important role in determining the microstructure and properties of sprayed deposits. However, few investigations have been carried out on this topic. The current work presents the results of an experimental and computational study of the influence of injector geometry and gas mass flow rate on particle dynamics at injector exit and in the plasma jet. Two injector geometries were tested: a straight tube and a curved tube with various radii of curvature. Zirconia powders with different particle size range and morphology were used. A possible size segregation effect in the injector was analyzed from the space distribution of particles collected on a stick tape. The spray pattern in the plasma jet was monitored from the thermal radiation emitted by particles. An analysis of the particle behavior in the injector and mixing of the carrier-gas flow with the plasma jet was carried out using a 3-D computational fluids dynamics code.

The gas industry not only offers the most effective gas for all thermal spray processes, it also provides a variety of supply concepts and hardware with which maximum profitability can be achieved. The operator of the thermal spray equipment is responsible for ensuring that sufficient gas quantities are available at all times, comparable to the logistics involved in spray material management. Linde is now offering a fully automatic gas supply concept, including everything from consultancy and installation, through to the types of gases which can be used. The customer can therefore choose to manage his stocks himself as before, or to have the gas delivered and the bundles replaced by the supplier. With a minimum of time and effort, this electronic aid enables a reliable and fail-safe gas supply

The use of cored wires for thermal spraying is a relatively new development that is being rapidly utilized for arc spray in a wide variety of applications. This paper will discuss the existing applications and industries in which cored wire coatings are used. Additionally, this presentation will cover the effect cored wires have had on the use of other types of thermal spray equipment. The paper will close with a trend analysis that discusses the applications of the future.

In design, construction and use of thermal spray equipment, very often several companies or persons are involved. Then, in the most cases it isn't clear who is the responsible body for the safe use of the machines. Is it the manufacturer or the user? Is the worker liable for incidents or is the employer in charge. This paper will show some reasonable solutions for these questions with a view to the related legal aspects. It explains, especially when there are several suppliers involved for one integrated system, why the responsibility for health and safety aspects have to be defined before the equipment is put into operation.

Turbine blades are generally protected by thermal barrier coatings (TBCs) against high temperature oxidation and corrosion. A novel method has been developed to prepare nanostructured Al 2 O 3 powders for thermal-spraying (atmospheric plasma spray) with high flowability. In this method, nano Al 2 O 3 powders are granulated and then heat treated at 200°C which become suitable to be used in thermal spraying equipment. The normal Al 2 O 3 and granulated nano Al 2 O 3 powders were sprayed separately by using an atmospheric plasma spray device onto a typical TBC consisting of a superalloy bond coat and an YSZ top coat. Then, TBC/ normal Al 2 O 3 and TBC/ nano Al 2 O 3 coatings were oxidized at 1000°C for 24h and allowed to form the thermally grown oxide (TGO) layer onto the bond coat (NiCrAlY layer). The flowability of the granulated nano Al 2 O 3 powders was studied by using a Hall flowmeter. The microstructural characterization showed that the granulated nano Al 2 O 3 powders had very high flowability. The increased apparent density and flowability of the granulated nano Al 2 O 3 powders had substantially reduced the micro-cracks and interconnected porosities in the coating in comparison with normal Al 2 O 3 coating. The thickness of the TGO layer in YSZ/ normal Al 2 O 3 coating was higher in comparison with YSZ/ nano Al 2 O 3 coating after oxidation. Thus by using nano Al 2 O 3 as a third layer, the thickness of the TGO layer and oxidized regions inside the bond coat decreased effectively which led to less mechanical stresses and can cause the improvement of TBC life.

Thermal-spray standards in the United States are developed by several professional societies that include American Society for Testing and Measurement (ASTM) for test & measurements methods and composition specifications; American Welding Society (AWS) for feedstock, equipment acceptance, application process, training & certification; American Water Works Association (AWWA) for thermal-sprayed zinc as potable water tank lining; International Association of Corrosion Engineers (NACE) for corrosion protection processes and inspection; and Society of Protective Coatings (SSPC) for test & measurement methods, application specification & inspection in regards to protective coatings for the protection of steel. This paper provides information on various standards set by these bodies.

Trends of thermal spraying technology in Japanese steel industry is summarized by investigating the patent applications filed in Japan Patent Office in the past 20 years from FY1990 to FY2009. The total number of patents filed in 8 Patent Offices (Japan, United States, Europe, China, Korea, Russia, Brazil and India), retrieved by the International Patent Classification symbol C23C4/00 (IPC index key: Coating by spraying the coating material in the molten state ), is 15,082. The ratio of patent applications filed in each Patent Office is as follows: JP (39%), US (22%), EP (17%), CN (9%), KR (6%), RU (3%), BR (3%) and IN (1%). The database used in this study is from commercially available “PatBase”. Number of patent applications of thermal spray technology (C23C4/00) in Japan is 4,369. Among these patents, the ratio of patents related to steel industry filed by major Japanese steel companies is 13% of total patents of every industrial segment in Japan. These patents are classified according to (1) coating applications in the process of steel production lines, (2) performances and effects obtained by coatings, .and (3) coating materials. In this paper, current status and future trend of thermal spray technology in Japanese steel industry is discussed.

Preface for the International Thermal Spray Conference 1998.

According to a recent survey, the thermal spray market in Japan is approximately 100 billion yen. The market consists of three sectors, coating services (45 billion yen), in-house production (45 billion yen), and sales of thermal spray equipment and consumables (10 billion yen). This paper provides an overview of the coating services market broken out by application segments. It also discusses future trends.

This paper provides a summary of the status and potential of thermal spray activities in India. A meaningful indicator of the future growth of thermal spray technology in India is the rapid rise in the number of job shops that offer thermal spray coating services. The number of captive units meeting in-house coating needs has also increased markedly in recent years. These trends have in part been fueled by an increase in the number of home-grown Indian companies manufacturing spray systems, handling equipment, and performance evaluation test rigs. Research in areas such as cold gas dynamic spraying (CGDS) and solution precursor plasma spraying (SPPS) is also on the rise in India.