Development and comparison of HVOF and laser DED methods for depositing TiC-Ni3Al based coatings

Abstract

Deposition of TiC-Ni3Al composite coatings by high velocity oxyfuel (HVOF) and directed energy laser deposition (DED) was investigated for enhancements, modifications and/or repairs of steel surfaces with extensive wear and oxidation characteristics. Gelation of sodium alginate was employed as an aid to preposition aqueous suspensions, comprised of micron-sized ceramic-metal particles, into micron-sized spherical ‘cermet’ feed-stock powders. Spraying a sodium alginate containing ceramic-metal particle suspension, with a suitable air atomizing nozzle, into an aqueous bath was outlined as a solution to produce nominally spherical ‘cermet’ feedstock for HVOF thermal spraying. Consequently, dip coating of substrate in colloidal suspension containing ceramic-metal particles, has been suggested as an efficient method for layer-by-layer deposition of preplaced cermet feed stock prior to the laser processing. Processing parameters were identified in the case of both HVOF and DED deposition procedures for optimum structural and mechanical characteristics of fabricated builds.