This paper examines WC based coatings with high-alloy binders with regard to their structure, corrosion behavior and wear. The coatings are compared to conventional coatings with respect to corrosion and wear. The coatings were made using HVOF spraying of various powders. All powders examined were produced by agglomeration/sintering, that is by agglomeration of metal particles with WC particles and subsequent sintering. Some powders have been made using pre-alloyed metal particles. The paper also examines a mixture of ceramic-metallic powder and purely metallic powder. Various methods are used to characterize the powders and coatings. Paper includes a German-language abstract.

This paper compares three thermally sprayed coatings with different carbide types in a NiCr matrix (25% by volume) with regard to their erosion, corrosion, and wear resistance. The three types of carbide are WC, chromium carbide, and TiC. The coatings were sprayed with the Sultzer-Metco Diamond-Jet 2600 equipment. All coatings were produced with the same spray parameters. If the sand particles hit the surface at high angles of impact, the WC coating is better than the other two coatings in terms of erosion/corrosion resistance. Micro-abrasive wear tests also showed the WC coating was superior (slightly better than the TiC coating). The corrosion properties of the coatings were almost the same. Paper includes a German-language abstract.

In corrosive media the wear resistance of ceramic-metallic coatings is dependent on the corrosion resistance of the metal matrix. Other factors that will affect the coating deterioration are the corrosivity of the medium and any galvanic interaction from the surrounding material. This paper presents results from a study where different types of WC(Co/Cr/Mo/Ni) powders have been sprayed by HVOF, Diamond Jet 2600 Hybrid equipment. The properties of the sprayed coatings have been verified by metallographic studies and by erosion-corrosion testing both under corrosive and non-corrosive conditions. The results clearly demonstrate the importance of having a metal matrix at least as corrosion resistance as the surrounding materials. When wear exposed components in pipe systems, pumps or valves are coated with a WC type coating, the corrosion resistance of the metal matrix should be compatible to the material of the rest of the system. This is especially important when the surrounding materials are corrosion resistant alloys as stainless steels, where the coatings otherwise will act as an anode.

This paper reviews some data regarding the combined effect of erosion and corrosion of thermal spray ceramicmetallic coatings and their potential application in sea water and production systems for the oil industry. The paper also presents recent research results from SINTEF Corrosion and Surface Technology with respect to development of new and better ceramic-metallic coatings from the Norwegian coating industry. It has been shown that taking new high velocity spraying technology into use in combination with recent developed powders, the result is a more corrosion and erosion resistant coating than the traditional and most often specified type Praxair LW45.