Optimization of Detonation Spraying Parameters for (Ti, Cr)C–Ni Composite Coatings

Abstract

The influence of detonation spraying 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 containing 18, 25, and 33 wt.% Ni onto a steel substrate. The particle-size distribution 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 probe microanalysis. 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 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 upward when the nickel content changed from 18 to 33 wt.% in the (Ti, Cr)C–Ni composite powders. The 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 coating 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.