Since the introduction of the HVOF process by J. Browning in 1982, gun design and spraying parameters have changed to achieve increasing gas resp. particle velocities. One exeption among the up-to-date HVOF systems is the GTV K2 Burner System. From the very first design study, special attention was payed to optimum heat management within the gun. This article discusses the principles of HVOF burner system, that is designed with special regard to heat management, illustrates gun behavior, and describes the results of various GTV K2 applications. The discussion covers the processing of fine powder grades, low melting materials, and oxidization sensitive materials. It is concluded that, solely in case of the K2, the injected kerosene is completely burned inside the combustion chamber.

Today, more than ever the greatest progresses are reached in the field of microprocessor technique. Electronic devices are becoming smaller and smaller and showing at the same time higher performance. This fact has an effect on equipment control in mechanical engineering. No equipment can be used economically without PLC and PC. Moreover, it is impossible to build one without using them. Since a long time electronic components like PLC are considerable reasonable in pricing compared to supposing simple mechanical or electro mechanical systems. At the same time higher recommendations are expected from operator and service persons. Thermal Spray guns and systems are in a steady further development. Beside the request for high power systems there is a demand coming up for smaller and more affordable systems. Nevertheless, high power plasma guns are also to be focused on due to the fact that there is still the demand for ceramic coatings on big components.

With the goal to improve the plasma spraying technique a considerable number of plasma gun types using different physical principles have been developed in the past. In this paper for conventional DC discharge plasma torches widely used in industry, some aspects of operation as arc fluctuations and non-symmetric plasma jets are discussed. Different construction principles with single or multiple electrodes as well as with one-piece or cascaded nozzles are compared. Finally a new torch concept is presented.

The characterization of the adhesive and cohesive strength of thermally sprayed coatings is often evaluated according to given standardized testing procedures. These tests require the preparation of normally large coupons which have to be fixed together using an appropriate adhesive. Additionally they need time for preparation (e.g. annealing/curing of the adhesive) and require test equipments normally not available at job shops for coating development. One of the largest limitations of these tests is the applicability only for non-porous coatings, and in some cases the limited strength of the adhesive. Within a European CRAFT research project on “standards, measurements and testing”, a new shear test method was developed to characterize the mode and value of failure of thermally sprayed layers in a more reliable and less limited manner. This new shear test does not need any adhesive and yields more intrinsic information on coating quality than conventional tensile tests.

The application of wear resistant coatings onto the wall of aluminium engine cylinder bores by thermal spray have seen much development over the last 10 years, with regards to both equipment design and also to the material system used. While the technology has been successful in allowing the implementation of aluminium engine blocks into mass production, there is still room for improvement. One area that can be improved is the preparation of the substrate material in order to allow a good adhesion of the thermal spray coating. Grit blasting, a traditional preparation technique, is undesirable for a mass production environment due to the risk of the assembly areas becoming contaminated with grit. Therefore, an alternative method has been sought that can offer a suitable bond strength without introducing potential risks in the manufacture line. In this study, NiAl bond coats were sprayed onto aluminium substrates using the Plasma Transferred Wire Arc (PTWA) coating system developed by Ford Motor Company. A variety of surface preparation techniques, including traditional and some more novel methods, were used and analysed with respect to bond strength, ease of application and cost.

This paper introduces a new three-cathode plasma burner and explains how it functions in comparison to conventional plasma guns. Paper text in German.

The EC Machine Directive entails consequences in correlation for mechanical engineering in general with regarding the safety for people and for the environment. A few components which should be taken into consideration for the safe operation of thermal-spraying installations are explained in the contribution. The technical functioning and working modes of gas warning sensors, return protective devices and a programmable controller as a possible safety device are described. The objective is to awaken a certain degree of sensitisation on the part of the practice-oriented user to indispensable safety components in modern spraying-installation technology. Paper text in German.