“…Figure 13 is the XRD pattern of the laser cladding coating after air oxidation at 1100 • C × 120 h. It can be seen from the figure that the laser coating after oxidation is mainly composed of four phases, TiO 2 (PDF 96-900-4143), HfO 2 (PDF 96-154-5065), Ta 2 O 5 (PDF 96-210-2125) and Nb 2 O 5 (PDF 96-152-8679). This is consistent with what has been reported in the literature [17,27,28]. However, no diffraction peaks of MoO 3 and B 2 O 3 were found, which may be due to the evaporation of MoO Figure 13 is the XRD pattern of the laser cladding coating after air oxidation at 1100 °C 120 h. It can be seen from the figure that the laser coating after oxidation is mainly composed of four phases, TiO2 (PDF 96-900-4143), HfO2 (PDF 96-154-5065), Ta2O5 (PDF 96-210-2125) and Nb2O5 (PDF 96-152-8679).…”
“…Kirnbauer et al [16] reported that (HfTaVWZr)B 2 coating still maintains a single-phase structure at 1200 • C, and the high-entropy borides decompose into a very small amount of (HfTaZr)B 2 and (VW)B 2 at 1400 • C, most of which are still single-phase solid solutions, with the mechanical properties almost unchanged. Zhang et al [17] reported that (Hf 0.25 Zr 0.25 Ti 0.25 Cr 0.25 )B 2 -SiC-Si coating can protect the C/C matrix from oxidation for more than 205 h at 1700 • C, which is mainly due to the formation of a dense and stable Hf-Zr-Ti-Cr-Si-O oxide layer. Up to now, there have been limited reports on high-entropy boride coating, especially the study of the oxidation properties of high-entropy boride composite coating prepared with laser cladding at high temperature.…”
In order to improve the high-temperature oxidation resistance of Ti60 alloy, a Ti-Hf-Mo-Ta-Nb-B composite coating was prepared on Ti60 alloy with Ti, Hf, Mo, Ta and Nb powder and B powder as raw materials using laser cladding. The microstructure and oxidation behavior of the coating before and after oxidation at 1100 °C × 120 h in static air were studied with XRD, SEM, EDS and isothermal oxidation techniques. The results show that the coating was mainly composed of six phases, (Ti0.2Hf0.2Mo0.2Ta0.2 Nb0.2)B2, TiB, HfB2, Mo4.00 B3.40, TiHf and Hf1.86Mo0.14. The high-temperature oxidation of the coating and Ti60 alloy followed parabolic law, and the oxidation weight gain rate of the coating after 110 °C × 120 h was only 1/4.8 of that of the Ti60 alloy. The improvement of the high-temperature oxidation resistance of the coating may benefit from high-temperature oxidation resistance (Ti0.2Hf0.2 Mo0.2Ta0.2Nb0.2)B2, HfB2 and TiB boride ceramic phases.
“…Figure 13 is the XRD pattern of the laser cladding coating after air oxidation at 1100 • C × 120 h. It can be seen from the figure that the laser coating after oxidation is mainly composed of four phases, TiO 2 (PDF 96-900-4143), HfO 2 (PDF 96-154-5065), Ta 2 O 5 (PDF 96-210-2125) and Nb 2 O 5 (PDF 96-152-8679). This is consistent with what has been reported in the literature [17,27,28]. However, no diffraction peaks of MoO 3 and B 2 O 3 were found, which may be due to the evaporation of MoO Figure 13 is the XRD pattern of the laser cladding coating after air oxidation at 1100 °C 120 h. It can be seen from the figure that the laser coating after oxidation is mainly composed of four phases, TiO2 (PDF 96-900-4143), HfO2 (PDF 96-154-5065), Ta2O5 (PDF 96-210-2125) and Nb2O5 (PDF 96-152-8679).…”
“…Kirnbauer et al [16] reported that (HfTaVWZr)B 2 coating still maintains a single-phase structure at 1200 • C, and the high-entropy borides decompose into a very small amount of (HfTaZr)B 2 and (VW)B 2 at 1400 • C, most of which are still single-phase solid solutions, with the mechanical properties almost unchanged. Zhang et al [17] reported that (Hf 0.25 Zr 0.25 Ti 0.25 Cr 0.25 )B 2 -SiC-Si coating can protect the C/C matrix from oxidation for more than 205 h at 1700 • C, which is mainly due to the formation of a dense and stable Hf-Zr-Ti-Cr-Si-O oxide layer. Up to now, there have been limited reports on high-entropy boride coating, especially the study of the oxidation properties of high-entropy boride composite coating prepared with laser cladding at high temperature.…”
In order to improve the high-temperature oxidation resistance of Ti60 alloy, a Ti-Hf-Mo-Ta-Nb-B composite coating was prepared on Ti60 alloy with Ti, Hf, Mo, Ta and Nb powder and B powder as raw materials using laser cladding. The microstructure and oxidation behavior of the coating before and after oxidation at 1100 °C × 120 h in static air were studied with XRD, SEM, EDS and isothermal oxidation techniques. The results show that the coating was mainly composed of six phases, (Ti0.2Hf0.2Mo0.2Ta0.2 Nb0.2)B2, TiB, HfB2, Mo4.00 B3.40, TiHf and Hf1.86Mo0.14. The high-temperature oxidation of the coating and Ti60 alloy followed parabolic law, and the oxidation weight gain rate of the coating after 110 °C × 120 h was only 1/4.8 of that of the Ti60 alloy. The improvement of the high-temperature oxidation resistance of the coating may benefit from high-temperature oxidation resistance (Ti0.2Hf0.2 Mo0.2Ta0.2Nb0.2)B2, HfB2 and TiB boride ceramic phases.
“…To fully understand the excellent anti-oxidation performance of HMSS/SS coating at 1700°C, it is essential to analyse the evolution of the morphology and phase composition of each oxidation stage. Figure 5 (a) Oxidation curve of HMSS/SS-coated samples at 1700°C; (b) comparison of oxidation resistance with the reported HfB 2 -based coatings in 1700°C [4,19,24]. …”
Section: Resultsmentioning
confidence: 99%
“…(a) Oxidation curve of HMSS/SS-coated samples at 1700°C; (b) comparison of oxidation resistance with the reported HfB 2 -based coatings in 1700°C [4,19,24]. …”
Section: Resultsmentioning
confidence: 99%
“…After oxidation for 270 h, the specimen loses a significant amount of weight with a mass loss rate of 0.99%. Figure 5(b) provides a comparison of the research with the claimed oxidation resistance capabilities of the HfB 2 -based coating at 1700°C [4, [19][20][21][22][23][24]. Compared to other reported coated samples, it is exciting that the prepared HMSS/SS coating possesses a longer protection time with less weight loss.…”
Section: Oxidation Performance Of the Hmss/ss Coating At 1700°cmentioning
Slurry impregnation and gaseous Si infiltration were effectively used to produce compact MoSi 2 -doped Si-HfB 2 -SiC/Si-SiC (HMSS/SS) coatings with a thickness of 250 μm to protect carbon fibre reinforced carbon (C f /C) composites from oxygen corrosion at 1700°C. The HMSS/SS coating obtained with a mosaic structure makes it possible to protect C f /C composites at 1700°C for 276 h and the mass reduction is only 0.99%. The pinning effect of the embedded hafnia, the generated MoB together with the Hf, Mo co-doped Si-based glass layer, which successfully prevented the migration of oxygen, was attributed to the superior oxidation protection ability of the HMSS/SS coatings. This work provides a practical method for successfully extending the service life of C f /C composites in the aerospace industry.
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