The role of metal powder properties on the tribology of cold sprayed Ti6Al4V-TiC metal matrix composites

Abstract

Ti6Al4V-TiC metal matrix composite (MMC) coatings were cold sprayed using spherical and irregular Ti6Al4V powders manufactured with plasma gas atomization and the Armstrong process, respectively. Composite coatings deposited using irregular powders showed higher ceramic retentions and lower porosity compared to spherical powders coatings. Sliding wear tests were performed at two different normal loads using a spherical WC-Co ball as counterface. Wear test results showed that at similar ceramic contents, spherical powder (SP) composites exhibited abrasive wear mechanisms with high coefficients of friction (CoF) and wear rates. In irregular powder (IP) composites, islands of tribolayers, comprised of fragmented TiC and TiO2 particles, resisted the localized shear deformation leading to low wear, and with free carbon from the TiC particles also lowered the CoF. Increase in ceramic content in the IP MMCs to 23% led to higher coverage of wear track area with tribolayers and further lowered the wear rate. At higher load, 23% TiC composite coatings showed a more continuous tribolayer, whereas lower ceramic content MMCs showed no significant formation of tribolayers. The formation of a highly continuous tribolayer at higher load (in 23% TiC MMC), led to extremely low CoF (~ 0.25) compared to other coatings along with low wear rate. Electron channel contrast imaging and transmission electron microscopy analysis of the worn subsurface under the tribolayers showed coarse-grain microstructures compared to the bare regions of the wear track (i.e. without tribolayer coverage).The formation of coarser grain microstructures indicated less stress transfer to the subsurface both due to the high hardness and lubricating nature of the tribolayers.

Perspectives on Developing Burn Resistant Titanium Based Coatings—An Opportunity for Cold Spraying

“…Further, the poorly bonded Ti 2 Cu is easy to fall off, aggravating the friction on Ti. Furthermore, the deposition efficiency of the hard particles in mixed spraying is low, and the content in the coating is significantly lower than that of the original mixed powder composition [63]. The rebound and erosion of the hard particles simultaneously reduce the deposition efficiency of Ti.…”

“…Initially, adding a hard reinforcing phase reduces the Ti coating porosity; however, it cannot obtain a high-density structure. For instance, Ti-TiC [62], Ti6Al4V-TiC [63], Ti6Al4V-CoCr [64], and other coatings still result in significant pores (Figure 8), especially at the interface between hard particles and Ti. Further, the pores are not conducive to the burn-resistant performance of the coating.…”

Advanced Functional Metal-Ceramic and Ceramic Coatings Deposited by Low-Pressure Cold Spraying: A Review

“…Particle reinforced metal matrix composite (PRMMC) coatings consist of a ductile matrix (pure metal or metal alloy) and hard reinforcement phase (different metal, ceramics, intermetallic phase, organic or inorganic material), and as a result, combine properties of both materials, e.g., resistance for high-temperature mechanical loading, maintaining increased durability [77,78]. Due to high strength, hardness, chemical inertness, high melting point, and many functional applications, ceramic powder is the most commonly selected material for reinforcement in PRMMC coatings [77,[79][80][81][82]. The uniformly distributed, coherent, and continuous hard phase in the metallic matrix increases the following properties of the coating: (i) mechanical properties, such as strength, elastic modulus, hardness, and wear resistance [81,83,84], (ii) chemical properties, including corrosion resistance [62,82,83], and (iii) physical properties, e.g., high-temperature stability [79,85], or electrical and thermal conductivity [62,[86][87][88].…”

Laser‐Directed Energy Deposition Additive Manufacturing of Nickel–Titanium Coatings: Deposition Morphology, Microstructures, and Mechanical Properties

“…[4] With the development of modern industry, the low hardness and poor wear resistance of Ti-6Al-4V are struggling to meet surging performance demand from engineering materials. [5] To improve the surface tribological properties of Ti-6Al-4V components, various ceramic materials (such as TiB, [4] TiB 2 , [6] and TiC [7,8] ) or metal materials (such as Ta, [9] Zr, [10] Nb, [10] and NiTi [11] ) were used to modify the Ti-6Al-4V substrate surface. Notably, NiTi alloys have attracted much attention due to their unique superelasticity, excellent wear resistance, and ability to achieve good interfacial bonding with the Ti-6Al-4V substrate.…”