Development of Thin WC-12Co Coatings Manufactured by HVOF-spraying

The thicknesses of HVOF-sprayed WC-12Co wear protective coatings usually range between 200 – 500 µm. These thicknesses ensure a homogeneous coating structure as well as sufficient material reserves for an efficient wear protection. For applications which require high shape accuracies, a cost intensive finishing of the thick coatings, in terms of grinding and polishing, is necessary. Thus, smooth and thin coatings are favored.

In this study, thin HVOF-sprayed carbide coatings < 100 µm are developed by means of fine sintered and agglomerated WC-12Co powders (2 – 10 µm). The use of fine powders enables the reduction of the coating thickness down to values below 20 µm. To influence and adjust the thickness of the coatings the powder flow, the gun velocity and the track pitch were systematically varied. During these tests the porosity, the hardness and the roughness of the coatings were scrutinized.