The control of the coating quality becomes more and more important. Infrared methods are well introduced in industry for several types of inspections. The lock-in thermography is based on modulated heat flux and is proved for composite materials and electronic components. In combination with an IR-camera seems to meet the requirements of a modem quality control system. The off-line measurement takes about 3 up to 5 minutes depending on the geometry of the surface. The paper gives an overview on the principle, the technical details of the measurement and the correlation of the detected signals and the coating properties will be discussed. The accuracy concerning the thickness is determined for different coatings (e.g. WC-Co).

Lock-in thermography is a nondestructive inspection method based on modulated heat transport in combination with infrared imaging. Measurement times are relatively short, about 3 or 4 minutes, and the method is amenable to inspecting a wide range of large and small parts. This paper describes the basic principle behind the method and its application to different thermal sprayed coatings (e.g., Cr-steel, Al2O3). It explains how the test samples were prepared with artificial defects simulating delaminations, inclusions, and other types of imperfections and how the method performed in each case.

The following contribution deals with carbide composite powders. These composite powders were made by the SHS-process. The present work is a result of a co-operation between the Institute for Powder Metallurgy Minsk (PMI) and the Department of Composites and Surface Technology at the Chemnitz University of Technology (TUC). The main aspect of this research activity is the improvement of the wear protection due to the deposition of the composite coatings. Paper text in German.

Thermal spraying of composite materials is an effective method for surface protection against wear and corrosive attacks. There are different possibilities to produce composite-materials for thermal spray applications. The self-propagating-high- temperature-synthesis (SHS) is a very promising method to obtain fine carbide particles homogeneously distributed in a metal matrix. In the present investigation TiC-based composite materials were applied to steel substrate samples by thermal spraying. The coating characteristics were determined by the use of different investigation methods. The results of the wear test show the great potential for industrial application. Further progress is expected from the optimisation of the thermal spray processes and the compounds composition. Paper includes a German-language abstract.

In order to improve the properties profile of thermally sprayed coats (in particular, the corrosion resistance), the coats are, amongst other items, posttreated with organic and/or inorganic posttreatment media. The coat combinations used are Al 2 O 3 /TiO 2 (87/12), APS-sprayed, and WC-Co (88/12), HVOF-sprayed. Commercially available sealants and two products from other areas of application were used for sealing purposes. The main contribution of the sealing agents to the anti-corrosion protection lies in the fact that they seal open, (inter)connected pores and/or cracks and thus prevent corrosive media from penetrating into the sprayed coat and from reaching the substrate. In this respect, the best results are achieved with sealing agents which form a dense film extending into the pores of the coat. The component underneath can be protected optimally by the combination of the sprayed coat and the sealing agents. Paper text in German.

Laser shock processing (LSP) is a surface treatment similar to shot peening, in which the compressive stresses in the material are created by laser-induced mechanical impacts. The tensions are of sufficient intensity to modify the microstructure and properties. In this paper, the laser pulses are generated with a power density of 5 to 8 GW/centimetres square with a neodymium laser. The glass laser is used to treat Al+SiC composite coatings, which were initially applied using the high-speed oxygen fuel spray technique. The laser-processed samples are prepared metallographically and examined for their microstructure with a scanning electron microscope. The latter is also used to investigate the surface morphology of laser-treated samples. Finally, the microhardness and the vibration wear resistance of the coatings are tested and compared with the data obtained for the samples in the sprayed state. Paper includes a German-language abstract.

The characterisation of the effectiveness of sealing was studied by metallographical investigations as well as comparing the investigations with respect to the corrosion- and wear behaviour of the used thermal sprayed coatings and last but not least by measuring of the insulation resistance of the coating system. The obtained results show that there are differences between the used sealants and it is possible through a mechanical treatment of sealed coatings to remove the sealants from the coatings. In the corrosion test the sealants show their efficiency. The sealants insulate the open porosity and prevent the corrosion attack owing to the interconnected pores.