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A kind of multiscale β-sialon grain-reinforced Al2O3 matrix composite ceramic tool material, named ASN, was prepared and studied. For the ASN, β-sialon (molecular formula: Si4Al2O2N6) was synthesized in situ by a hot-pressing and solid-solution reaction process. A total of six samples were prepared at varying sintering temperatures and holding times under vacuum conditions. The solid solution reaction mechanism of β-sialon, the phase composition, mechanical properties, microstructure, and strengthening and toughening mechanisms of the composite ASN were investigated. As a result, within the experimental parameters, an optimal ASN tool material was obtained under a pressure of 32 MPa and at a temperature of 1550 °C for 20 min. The tested mechanical properties of the optimal sample were as follows: flexural strength 997 ± 59 MPa, fracture toughness 6.4 ± 0.3 MPa·m1/2, Vickers hardness 18.2 ± 0.4 GPa, and relative density 98.1 ± 0.2%. According to crystal defect theory, the solid solution reaction mechanism of in-situ-synthesized β-sialon in an Al2O3 matrix involves a double mechanism of unequivalence (or hetero-valence) and interstitial filling. The multiscale β-sialon grains mainly consisted of four grains, which were elongated β-sialon grains with a diameter of 0.3–0.4 μm and an aspect ratio of 6–9, elongated β-sialon grains with a diameter of 70 nm and an aspect ratio of 10, β-sialon whiskers with a diameter of 0.2 μm and an aspect ratio of 12–15, and intragranular β-sialon whiskers with a diameter of 70 nm. The mechanical properties were improved due to strengthening and toughening mechanisms, such as mixed structure mode (intergranular and transgranular), elongated grain pullout, interface bonding, crack reflection, pinning, and bridging. [ABSTRACT FROM AUTHOR]

The compatibility of tetraethylammonium decahydrodecaborate (BHN) with some energetic components and inert materials of solid propellants was studied by DSC method, where glycidyl azide polymer (GAP), cyclotrimethylenetrinitramine (RDX), cyclotetramethylenetetranitroamine (HMX), lead 3-nitro-1,2,4-triazol-5-onate (NTO-Pb), hexanitrohexaazaisowurtzitane (CL-20), 3,4-dinitrofurzanfuroxan (DNTF), N-guanylurea-dinitramide (GUDN), aluminum powder (Al, particle size=12.18 μm) and magnesium powder (Mg, particle size: 44-74 μm) were used as energetic components and polyoxytetramethylene-co-oxyethylene (PET), polyethylene glycol (PEG), addition product of hexamethylene diisocyanate and water (N-100), hydroxyl terminated polybutadiene (HTPB), cupric adipate (AD-Cu), cupric 2,4-dihydroxy-benzoate ( β-Cu), lead phthalate ( ϕ-Pb), carbon black (C. B.), aluminum oxide (Al2O3), 1,3-dimethyl-1,3-diphenyl urea (C2), di-2-ethylhexyl sebacate (DOS) and potassium perchlorate (KP), were used as inert materials. It was concluded that the binary systems of BHN with NTO-Pb, CL-20, aluminum powder, magnesium powder, PET, PEG, N-100, AD-Cu, β-Cu, ϕ-Pb, C. B., Al2O3, C2, DOS, and KP are compatible, and systems of BHN with GAP and HMX are slightly sensitive, and with RDX, DNTF, and GUDN are incompatible. The impact and friction sensitivity data of BHN and BHN in combination with the energetic materials under present study were obtained, and there was no consequential affiliation between sensitivity and compatibility. [ABSTRACT FROM AUTHOR]