Wear damage tolerance and high temperature oxidation behavior of HfB2:ZrB2–SiC composites

Study on Friction and Wear Behaviors of M42 High Speed Steel

“…These tiny holes make the matrix and wear debris combining more easily. Then a thick oxide layer will be formed with the wearing process [10][11][12][13][14][15]. Therefore, the worn oxide layer of J-M42 steel with more fine carbides is thicker than that of C-M42 steel.…”

Investigation of the Effect of Supersonic Flow of Dissociated Nitrogen on ZrB2–HfB2–SiC Ceramics Doped with 10 vol.% Carbon Nanotubes

“…The study of the obtained materials using Raman spectroscopy made it possible to establish ( Figure 3 ) that for both ZHS and ZHSC, intense modes of cubic silicon carbide with maxima at 801 (TO) and 976 cm −1 (LO) are observed, while ZrB 2 and HfB 2 are inactive in the Raman spectra. Some shifts in the position of the modes to the region of large shifts, with respect to the values 784–804 (for TO) and 968–975 cm −1 available in the literature [ 44 , 69 , 70 , 71 ], may be due to the high compressive stress concentrated in the ceramic on the SiC grains [ 72 , 73 ]. For the ZHS sample, the presence of some amount of impurity carbon is shown, which is expressed in the presence of two low-intensity broadened bands with maximums in the 540–550 and 600–610 cm −1 region, associated with amorphous carbon, as well as D- and G-peaks.…”

“…For the ZHS sample, the presence of some amount of impurity carbon is shown, which is expressed in the presence of two low-intensity broadened bands with maximums in the 540–550 and 600–610 cm −1 region, associated with amorphous carbon, as well as D- and G-peaks. The introduction of multilayer CNTs into the ZHSC sample resulted in the appearance of their characteristic peaks with maxima in the range of 1351–1361 (D-mode) and 1578–1594 cm −1 (G-mode) [ 39 , 40 , 44 , 45 , 46 , 74 , 75 ], overlapping with those characteristics of the impurity amorphized carbon remaining after the SiC carbothermic synthesis. The observed local maximum at 1619 cm −1 may be related to the presence of defective sp 2 carbon atoms at the ends of the aggregates of multilayer nanotubes.…”

“…The introduction of other modifiers from a number of refractory substances, such as carbides [ 22 , 26 , 27 ] and metal nitrides [ 28 , 29 , 30 ], as well as carbon materials [ 31 , 32 , 33 , 34 ], also has a significant influence on the mechanical characteristics of UHTCs. The use of carbon nanotubes (CNTs) as dopants is of high interest [ 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ]. In general, it is shown that such modification makes it possible to significantly increase the fracture resistance of materials (up to K IC = 6–10 MPa·m 1/2 ), but the process of making such ceramic composites requires the choice of hot-pressing temperature and maximum disaggregation of CNTs and their dispersion in the volume of materials.…”

“…In the literature, the influence of the introduction of CNTs on the mechanical characteristics of UHTC materials ZrB 2 (HfB 2 )–SiC is mainly considered, while the study of the oxidation features of similar composites or their behaviour in high-enthalpy jets of other gases is found in studies [ 38 , 40 , 44 , 46 ]. So, for the ceramic materials in the systems ZrB 2 +SiC, ZrB 2 +HfB 2 +SiC, and ZrB 2 +HfB 2 +SiC+CNT (6 vol.% CNT) obtained by the SPS (1850 °C, 30 MPa, holding time 10 min) method [ 38 ], the thermal behaviour at heating to 1200 °C in air current (20 mL/min) was studied: for doped CNT, the greatest increase in mass was fixed by oxidation.…”