Hetero-modulus alumina matrix nanoceramics and CMCs with extreme dynamic strength

Abstract

Applying the well-known alumina powders for matrix, different oxide and non-oxide ceramic submicron and nano-particles as additive materials, and investigating the impact of nitrogen atmosphere on sintering; the authors successfully developed new hetero-modulus alumina matrix ceramic composite materials, reinforced with submicron and nanoparticles of α-Si3N4 β-Si3N4, Si2ON2, SiAlON and AlN. Thanks to the new compacting technology with high speed flying punches in vacuumed N2 atmosphere developed by authors, phase transformation of α-Si3N4 and β-Si3N4 into cubic c-Si3N4 can be observed, creating so-called Si3N4-diamond submicron and nanoparticles in alumina matrix. The α-Si3N4, β-Si3N4, Si2ON2, SiAlON, AlN and c-Si3N4 diamond submicron and nanoparticles reinforced alumina matrix hetero-modulus nanoceramics have excellent mechanical properties and extreme dynamic strength. The dynamic strength was tested through collision with high density metallic flying bodies, with speed higher than 900 m/sec. Analytical methods applied in this research were laser granulometry, scanning electron microscopy, X-ray diffraction and energy dispersive spectrometry. Digital image analysis was applied to microscopy results, to enhance the results of transformation.