Current Situation and Future of the Thermal Spraying Industry in Europe and the World

  Prof. Dr. techn. E. Lugscheider, Prof. Dr.-Ing. K. Bobzin, J. Zwick

Surface Engineering Institute, RWTH Aachen University , Germany

.Abstract

Complexity and flexibility of thermal spraying as a surface coating technology is leading to continuously modified and improved processes, novel materials and fields of application. Current developments in those areas have the potential to consolidate existing markets as well as develop new markets in future, for example by improved processes for coating of internal diameters or replacement for electroplated hard chromium. In this short overview the current situation of the thermal spraying market and its future is analysed and a selection of the current developments and research activities are highlighted.

1. Introduction

Because of the flexibility and universal applicability of the thermal spraying technology, its market has been steadily growing in the past. Today thermal spraying still has not explored it full potential and is to develop further markets in future. The technology is continuously facing more specific requirements and increasing demands for various applications. To meet these demands, being in accordance to constantly rising quality standards and to provide solutions for challenging coating applications, the spraying processes and spray materials are subject to permanent development. Since the large number and remarkable variety of innovations are not allowing an exhaustive overview, a selection of important trends in the areas of spray processes, materials and applications as well as the continuously importance gaining field of diagnostics will be highlighted in this paper.

2. Market Situation

Today the global market for surface coatings is estimated to have developed with about 27 billion Euros less then 15 % of its full potential. Main applications for surface coatings today optic and electronic applications with a respective market share of more than 30 % as well as coatings in data storage systems that hold a share of almost 20 %. Surface protection coatings and herewith the main field of application for the thermal spray industry only have a share in the market of about 5 %. However, with improved coating technologies and increasing demands with respect to components and systems life-time and efficiencies as well as for environmental and health protection reasons, surface protection is expected to tremendously increase its share in future. Currently the largest thermal spraying markets are to be found in North America and Europe with 1.8 billion Euro (37 %) and 1.4 billion Euro (29 %) respectively, followed by Japan with 0.7 billion Euro (15 %). But with China being the most rapidly growing economy to date, this situation is about to change. China with a population of 1.3 billion and a growth of gross domestic product per year of 9.1 % has a huge market potential. If the turnover per habitant in China has reached a level of about 70 % compared to the turnovers in North America , Europe or Japan , it will take up more than 50 % of the global thermal spray market. Hence China represents the most important future market for thermal spraying and thermally sprayed products.

3. Spray Process Technology

The thermal spray technology shows a rapid annual growth rate of 5-10 % during the past decades, reflecting its potential for various fields of application. During the past 20 years the spray process technology has developed a significant trend towards high velocity spraying processes (Figure 1). The considerable increasing interest in high kinetic processes and their industrial usage are due to the advantageous properties for the production of very dense, hard and wear and corrosion resistant metal-based coating systems. Simultaneously the high kinetic processes allow for a minimum oxidation and phase transformations throughout the coating process due to the comparably low particle temperatures that are required for an efficient application of a spray coating.

Figure 1 : Global Market Development – relative use of spray technologies [Kas 98]

For a further reduction of material reactions during high velocity oxy-fuel flame (HVOF) spraying by reduction of the introduced thermal energy, different approaches have been proposed and followed. Among others they include modification of nozzle designs [Dol03] and usage of shrouds respectively, an increase of combustion chamber pressure [Sch03] as well as an optimised control of the flame temperature by purposeful selection of a suitable fuel type and method of supplying the fuel to the combustion process (Figure 2). The consequent continuation of this idea of a “cold” high velocity spray process has finally led to the relatively new concept of cold gas dynamic spraying, which has strongly gained interest during the past 5-10 years and was introduced into industrial application in 2003 for the first time (for the coating of processor heat sinks). Research activities on the field of cold gas dynamic spraying are presently focussing on the modelling and simulation of the process and the material behaviour during the high-speed impact of the relatively cold particles onto the substrate surface. Understanding of the splat behaviour and correlated influences is assumed to be a key knowledge apply the cold spray process also for other material systems and develop new fields of application.

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