Densification, microstructure evolution and mechanical properties of WC doped HfB2–SiC ceramics

Effects of SiC content on the densification, microstructure, and mechanical properties of HfB2–SiC composites

“…This guess could be evaluated by March-Dollase parameter extracted from Rietveld analysis 20 (demonstrated in Figure 6). In this study, the residual stress level (which is discussed in the following) in the samples were high, making it likely to form microcracks, 23 as observed by SEM analysis (Figure 2). Also, comparing the March-Dollase data with the aspect ratios (Table 2) shows a wonderful coordination between these two sets of data which, for instance, both have an extremum in 20 vol% SiC.…”

“…13,21,22 Ni et al 21 have attributed the drastic decrease in hardness to the possibility of the existence of the residual stress developed from the difference in thermal expansion coefficient between the numerous phases existing in the microstructure, and formation of the corresponding microcracks. In this study, the residual stress level (which is discussed in the following) in the samples were high, making it likely to form microcracks, 23 as observed by SEM analysis (Figure 2). These observations make the Ni's hypothesis in relation to reduced hardness in microcracks existence more probable.…”

Ultra-High Temperature Hfb2 - 30 % Sic Ceramics: Preparation and General Properties

“…При выдержке на воздухе 1 ч в муфельной печи при 1400 о С прирост массы СВТК составил (0,099 ± 0,007) мас. % (0,75 ± 0,09 мг/см 2 )* 6 ; по данным электронной микроскопии, толщина образующегося сплошного однородного стеклообразного оксидного слоя 3-4 мкм* 7 . Полученная пленка выступает барьером для дальнейшего окисления, при повторном окислении в тех же условиях изменения массы зафиксировано не было.…”

“…Жаростойкость можно улучшить, вводя в керамику на основе HfB 2 -SiC добавки TaSi 2 [10], MoSi 2 [1] и La 2 O 3 [9,20]. Каждая добавка являет-* 6 Статистика по 12 образцам размерами 3,0×4,0×45,0 мм. Несмотря на разную плотность различия по приросту массы между образцами СВТК по стойкости к окислению не наблюдали.…”

Mechanical activation-assisted autoclave processing and sintering of HfB2-HfO2 ceramic powders

“…The relative densification of the monolithic HfB 2 sintered by spark plasma sintering (SPS) under conditions of 2200 °C, 65 MPa and 5 min was 4 reported as 80 % [27]. Various additives such as SiC, WC, B 4 C, HfC, HfN, TiSi 2 , TaSi 2 and MoSi 2 have been added to enhance the densification rate of HfB 2 [1,11,[28][29][30]. Monteverde et al.…”