HVOF spraying was used to prepare coatings from mechanical blends of Cr 3 C 2 -25NiCr and NiCrBSi powders. The aim of the work was to study the influence of addition of a metallic phase on tribological properties of the coatings in sliding conditions. Tribological properties of the coatings were characterised under dry sliding. Addition of NiCrBSi decreased the coefficient of friction in high temperature, pressure and sliding speed.

In this work, HVOF sprayed hard metal multi-component Cr 3 C 2 -25Ni+10 vol-% solid lubricant coatings were prepared by HVOF spraying. CaF 2 , BN, MnS and WS 2 were used as solid lubricants. Powders were prepared by the spray drying and sintering method. This method produces homogeneous and spherical powders. Powders were sprayed with DJH 2600 HVOF-system. Microstructures, phase structures and compositions of powders and coatings were analysed with optical microscope, scanning electron microscope with EDS-analysator and x-ray diffractometer. The particle size distributions of sintered powders were determined by laser diffractometer. The amount of retained solid lubricant in the sprayed coatings was evaluated by EDS and compared to that in the spray powder. This study showed that spray drying and sintering method is a preferable method for manufacturing multi-component solid lubricant containing thermal spray powders. In sintering processes, solid lubricant phases remained in powders except for the Cr 3 C 2 -25Ni+10vol-%WS 2 -powder. Also, after HVOF spraying, coatings contained solid lubricants.

This paper describes the production of self-lubricating chromium carbide-nickel coatings using the HVOF spraying process. The present work deals with the preparation of Cr 3 C 2 -Ni + CaF 2 multicomponent powders and to spray them with a minimum loss of the CaF 2 solid lubricating phase. The powders are processed by atomization with subsequent sintering and qualification processes. The microstructure of the powder and resulting layers is characterized by SEM. The content of calcium fluoride in the sprayed layer is determined using the EDS method and compared with its content in the spray powder. Wear resistance is measured using a rubber wheel tester. Paper includes a German-language abstract.

In this study, Cr 3 C 2 +25NiCr hardmetal powder is mixed with small amounts of NiCr and CoCr powder and sprayed on steel substrates with a high-velocity oxyfuel torch. High-temperature friction tests are used to assess tribological performance and investigate the formation of tribolayers. The results of the study show that the friction coefficient of HVOF sprayed hardmetal coatings can be reduced by adding small amounts of low-friction powder to the feed stocks prior to spraying. The reduction in friction is the result of a tribochemical reaction that occurs on friction surfaces under contact conditions involving high temperature, pressure, and sliding speed. Paper includes a German-language abstract.

This work investigates the influence of powder characteristics on thermal spray coatings produced from titanium suboxide powders. The powders used were prepared from commercially fused and ground titanium dioxide reduced in a mixture of hydrogen and argon gas. Two particle sizes were produced and subsequently applied by atmospheric plasma and HVOF spraying. Originally melted and crushed powder fractions served as a reference. All deposits showed high wear resistance, particularly the HVOF-sprayed layers. Paper includes a German-language abstract.