High temperature oxidation behavior of micro/nanostructured WC-Co coatings deposited from Ni-coated powders using high velocity oxygen fuel spraying

Influence of aging in the temperature range 250–350 °C on the tribological performance of a WC-CoCr coating produced by HVOF

“…The "sponge-like" structure of the WO 3 phase, compared to the more compact one of the complex MWO 4 oxides, was already detected by other authors [15]. This morphology can be due to the growth mechanism of the WO 3 oxide on the tungsten carbide particles with the possible release of CO and CO 2 gas [16].…”

“…Concerning the two samples with no evident oxide on the surface (as received and 300 °C, 100 h), two broad bands around 800 cm -1 and 950 cm -1 are now present in their Raman spectrum. The first band may be ascribed at the formation of amorphous WO 3 , while the second one is related to the formation of tungstite, a hydrous tungsten oxide (WO 3 • xH2O) [14][15][16][17][18]. Moving to samples that were annealed at intermediate conditions (300 °C, 345 h and 350 °C 100h), where WO 3 was already present, Raman spectra after the sliding test show a reduction and an amorphization of the WO 3 , with a modification of the peaks detected in the corresponding aged coatings towards large bands.…”

Tribological behaviour of low-pressure plasma sprayed WC-Co coatings at elevated temperatures

“…At this temperature, much WO 3 appeared, especially for WC-12Co coating. The WO 3 was porous (Jafari et al , 2016) and could be easily scraped off. The oxides suffered the ploughing and accumulated on the sides of the worn tracks, leaving the coating surface to suffer the mechanical damage [Figure 7(g) and (h)].…”

Corrosion behavior of WC-Co coatings deposited by cold gas spray onto AA 7075-T6

“…Due to these properties, WC-Co coatings are widely used for applications where high mechanical performance and corrosion resistance are required, such as for the turbine blades of hydroelectric power plants, airplane landing gear, diesel engines, and rollers in paper industries [13][14][15]. WC-Co materials can be applied by the high velocity oxy-fuel (HVOF) method as coatings on steel [16][17][18][19][20][21][22][23][24][25][26] and aluminum alloys [7,8], as well as by the high velocity air-fuel (HVAF) method [27], plasma spraying [27][28][29][30], low pressure plasma spraying [27], and in the form of electrospark granules [31]. The resulting materials have been employed for various purposes when high resistance to abrasion, sliding, fretting, and erosion is required, with these properties depending on the density and particle size of the powder, spraying conditions, and the spray technique used [7,12,15,32].…”