Corrosion and Wear Properties of Composite Coatings Reinforced with Particles Produced by PTA on Steel Substrate in Different Atmospheres

Abstract

Titanium diboride (TiB 2 ) and titanium carbonitride (Ti(C,N)) coatings are widely used as reinforcing materials in applications demanding high corrosion and wear resistance. In this paper, plain carbon steel has been surface alloyed with TiB 2 by plasma transferred arc (PTA) technique using two different gas atmospheres. The first metal matrix composite (MMC) is produced with TiB 2 particles and argon as shielding and plasma gas. In addition, a mixture of Ar and 5% N 2 was used as shielding and plasma gas for producing of second MMC coating. The microstructure of both alloyed layers consists of primary titanium boride particles surrounded by a eutectic matrix, containing ferrite, eutectic boride, and titanium carbonitrides. The presence of these carbonitrides is more intense in the case of the N-enriched alloyed layer, as it was also proved via X-ray Diffraction. The alloyed layers are susceptible to pitting corrosion in 3.5% NaCl or 1 N H 2 SO 4 . The alloyed layer produced with nitrogen mixture gas is slightly more noble than the one produced with pure Ar. The metallic-ferritic matrix corrodes in 6% FeCl 3 * 6H 2 O leaving TiB 2 particles protruding from the matrix. The wear performance of both TiB 2 MMC depends on the counterbody (tool steel or alumina ball).

Electrochemical and DFT studies of laser-alloyed TiB2/TiC/Al coatings on aluminium alloy

“…5 indicate similar behaviour, with higher current density in the reverse cathodic scan direction, whereas the cathodic curve intersects the forward anodic scan, regardless of the specimen condition. This fact confirms that the substrate materials as well as both laser-alloyed coating in the as processed condition are susceptible to pitting corrosion [13]. A similar result was also found in the work of Darabara et al [13] who found that TiB2 and TiB2 + N alloyed layers are susceptible to pitting corrosion in 3.5 wt.% NaCl and 1 N H2SO4 solution.…”

“…When titanium diboride is immersed in NaCl solution at room temperature, it behaves like a passive metal due to the formation of a surface oxide film (hydrated titanium dioxide), whose protectivity decreases with the temperature and completely vanishes at 65 °C [15], [38]. In salt rich ocean water, a white film of tetravalent oxide titanium TiO2-H2O is formed, which hinders the material dissolution [13], [38]. Titanium carbide is relatively stable in mineral acids and alkali solutions, but decomposes in the presence of oxidizing acids [39].…”

“…A number of authors have evaluated the corrosion behaviour of steel coated with NiTi [11], CrN, NbN, Cr/Cr/N [7], Ni-P/TiN, Ni-P/CrN, Cr/TiN, Cr/CrN [12], TiN, TiBN [9] and TiB2 [9], [13].…”

Energy Density Effect of Laser Alloyed TiB2/TiC/Al Composite Coatings on LMZ/HAZ, Mechanical and Corrosion Properties

“…This fact confirms that both, the untreated Al alloy substrate and laser-alloyed coatings are susceptible to pitting corrosion [60]. Further, although TiC and TiB 2 coating generally exhibit good passivation behaviour in a NaCl solution, the active/Al part of the coatings prevented expressive passive plateau, as the potential continuously increases with increasing current density [1,3,60,61]. Table 1 lists the results of active dissolution potentials obtained from cyclic polarisation tests, including the average values of protective efficiency (P EF ).…”

“…Afterwards, increase in anodic current due to a stable pit growth or pit propagation is observed with a well-defined hysteresis in the reverse cathodic region. This fact confirms that both, the untreated Al alloy substrate and laser-alloyed coatings are susceptible to pitting corrosion [60]. Further, although TiC and TiB2 coating generally exhibit good passivation behaviour in a NaCl solution, the active/Al part of the coatings prevented expressive passive plateau, as the potential continuously increases with increasing current density [1,3,60,61].…”