Plastic deformation of polycrystalline zirconium carbide

A computational analysis of a ZrO2–SiO2 scale for a ZrB2–ZrC–Zr ultrahigh temperature ceramic composite system

“…The flexural strength of ZrB 2 slightly decreases from 351 to 342 MPa at 298 to 1073 K, respectively, with more dramatic lowering of its strength to 219 MPa at 1673 K. The Si 3 N 4 and SiC additions seem to increase the flexural strength at temperatures less than 1300 • C, though the strength of the ZrB 2 appear to extrapolate toward higher values than those attained by ZrB 2 with either Si 3 N 4 or SiC beyond 1500 K. For ZrC, Gridneva et al 7 determined the flexural strength, but it is significantly less than the compressive yield stress as reported by Darolia and Archbold. 8 The mechanics of a ZrO 2 -SiO 2 scale was considered for simulation, because of its successful protective characteristics on a ZrB 2 -SiC composite, as reported by Levine et al, 3 Hinze et al, 9 Opeka et al, 10 and Rezaie et al 11 The scale consists of a dual layer interphase with an outer SiO 2 amorphous layer covering primarily a ZrO 2 layer with SiO 2 located within the grain boundaries at temperatures greater than 1773 K. Although a B 2 O 3 -SiO 2 liquid forms because of the eutectic temperature of 372 • C at 67 mol% B 2 O 3 , 12 ichiometrically upon oxidation. As the silicate liquid covers the surface and seals pores or grain boundaries, the silicate serves as an effective diffusion barrier to oxygen diffusion.…”

“…The strength of ZrB 2 approximates 1.5 times better than ZrC at 1800 K, as determined by researchers [3][4][5][6][7][8] shown in Figs. 1 and 2.…”

Corrosion performance of NiAl intermetallic with Mo, Ga and Fe in neutral and alkaline media

“…Molybdenum was detected in the outer zone of the passive film, whereas nickel does not enter the passive film [12,13]. Zhang [14] studied the corrosion of aluminum implanted with Mo in 0.1 M NaCl and in 0.1 M NaCl+0.03 M NaHCO 3 , and found that the corrosion products on the surface were MoO 3 , Al 2 (MoO 4 ) 3 , MoCl 4 , AlCl 3 , Al 2 O 3 , and Al(OH) 3 . In alkaline solutions, non-protective NiO and Ni(OH) 2 was reported.…”

“…Its corrosion resistance is due to its ability to form a dense, adherent, protective aluminum oxide layer. However, NiAl is too brittle at room temperature and it has poor creep properties in respect to more conventional alloys [1][2][3][4]. Major efforts have been centered on enhancing the mechanical properties through grain refinement, micro and macroalloying as well as ductile phase toughening [5][6][7].…”

Synthesis of nanosized zirconium carbide by a sol–gel route

“…5,6 Unfortunately, they are characterized by brittle mechanical behaviour. 7 Over last years, nanosized grain materials have shown increasing interests due to new properties, which arise for example from the absence of extended defects in these particles. 8 In fact, unusual mechanical properties are expected in such materials, where the usual characteristic distance between two defects (e.g.…”