OPTIMIZATION OF DETONATION SPRAYING PARAMETERS FOR (Ti, Cr)C–Ni COMPOSITE COATINGS 

Abstract

The influence of detonation spraying process parameters on the porosity and adhesion of (Ti, Cr)C–Ni coatings was studied. These detonation coatings were applied from (Ti, Cr)C-based composite powders with Ni contents of 18, 25, and 33 wt.%  onto a steel substrate. The particle-size composition of the powders was −63+40 μm. A Dnipro-5M installation was used for detonation spraying. The flow rate of acetylene and oxygen, the air pressure for ejecting detonation products, and the spraying distance were varied in the spraying process. The structure of the coatings was examined by optical microscopy and electron microprobe analysis. The adhesion of the (Ti, Cr)C–Ni coatings was determined by the pin method, and the porosity was measured by the linear Rosival method. In the process of detonation spraying of (Ti, Cr)C–Ni composite powders, particles of double titanium–chromium carbide refined to 6–7 μm, contributing to the development of a fine and uniform structure of the detonation coatings. It was found that the detonation spraying parameters should be adjusted upwards with an increase in the nickel content from 18 to 33 wt.% in the (Ti, Cr)C–Ni composite powders. An increase in the nickel content from 18 to 33 wt.% resulted in higher adhesive strength and lower porosity of the coatings. In the research, an acceptable level of adhesive strength and porosity could not be reached for the (Ti, Cr)C–18 wt.% Ni detonation coating. The (Ti, Cr)C–33 wt.% Ni detonation exhibited the highest adhesive strength (101 MPa) and the lowest porosity (2%) among the studied coatings and is thus promising for further research of its tribological properties.