The elasto-plastic response of the precursor derived Si-B-C-N ceramics upon contact loading was determined by depth sensing nanoindentation technique. The indentation response of as-thermolyzed Si-B-C-N ceramic was compared with the heat-treated counterpart. The as-thermolyzed ceramic was X-ray amorphous and the heat-treated ceramic was phase separated and crystallized. The hardness and reduced elastic modulus values of the as-thermolyzed ceramic were ~16GPa and ~172GPa, respectively. The reduction in hardness to ~9GPa in the heat-treated ceramic was attributed to phase separation and crystallization of SiC and Si3N4. Furthermore, high elastic recovery with a plastic work ratio of ~0.3 was observed and ascribed to volume controlled deformation mechanism. © 2013 Elsevier Ltd.

Ravi Kumar

Department of Metallurgical and Materials Engineering

Ravindran Sujith

CONTROLLED DEFORMATION MECHANISM

DEPTH-SENSING NANOINDENTATION

Elastic recovery

ELASTO-PLASTIC RESPONSE

Experimental investigations

INDENTATION HARDNESS

POLYMER-DERIVED CERAMICS

REDUCED ELASTIC MODULUS

Hardness

Loading

Mechanical properties

Nanocomposites

nanoindentation

Phase separation

Silicon

Silicon carbide

Ceramic materials

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of the European Ceramic Society

Boron modified polyvinylsilazane was thermolyzed at 1300 °C under argon atmosphere and subsequently spark plasma sintered at 1600 °C in vacuum. The material was subjected to highly saline and constant vapor pressure environments individually to understand the influence of chemistry in propagating the subcritical cracks. The failure behavior in chloride environment was compared against humid environment using the data extracted from Raman spectroscopy, the thermodynamic characteristics of the environment and the micro-sized pore concentrations. The implications of the subcritical crack growth were derived by plotting ν-KI graphs for each of the samples to clearly distinguish between the effects of the surrounding mediums. The impulse to crack propagation was found to be resistive with variations in degree of crack growth alternating directly with the changes in porosity, surrounding atmosphere and defect density. The rate of energy dissipation and its hindrance at the crack tip were found to be a major player, among others, in reducing the crack propagation rate.

Ceramics International

Stress induced environmental damage in precursor derived SiBCN ceramics

The deformation behavior of pulsed electric current sintered silicon oxycarbide ceramics produced by the solid-state thermolysis of polyhydridomethylsiloxane at small-scale is investigated. The ceramics remained X-ray amorphous after sintering at 1300 °C in vacuum and a high density of ≈2.35 g cm-3 is achieved. The elastic constants of these ceramics are determined using non-destructive ultrasonic testing method. The elasto-plastic deformation under contact loading is determined using depth sensing nanoindentation technique. An indentation hardness of ≈11 GPa and reduced elastic modulus of ≈105 GPa is observed. The load-displacement curves display significant elastic recovery with an elastic work ratio of ≈0.71. The evolution of Hertzian cone cracks upon microindentation indicates an anomalous deformation behavior. Small-scale deformation behavior of pulsed electric current sintered silicon oxycarbide ceramics is investigated. The ceramics remained X-ray amorphous after sintering at 1300 °C in vacuum and a high density of ≈2.35 g cm-3 is achieved. An indentation hardness of ≈11 GPa and reduced elastic modulus of ≈105 GPa is observed. The load-displacement curves display significant elastic recovery with an elastic work ratio of ≈0.71. The evolution of Hertzian cone cracks upon microindentation indicates an anomalous deformation behavior. © 2013 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.

Advanced Engineering Materials

Small-scale deformation of pulsed electric current sintered silicon oxycarbide polymer derived ceramics

Journal of Advanced Ceramics

Progress of a novel non-oxide Si-B-C-N ceramic and its matrix composites

Conversion behaviour and resulting mechanical properties of polysilazane-based coatings

Acta Materialia

Determination of the mechanical properties of amorphous materials through instrumented nanoindentation

The Journal of Physical Chemistry C

Structural Evolution of Polymer-Derived Amorphous SiBCN Ceramics at High Temperature

Modelling and Simulation in Materials Science and Engineering

Modeling the mechanics of amorphous solids at different length scale and time scale

Experimental investigation on the indentation hardness of precursor derived Si-B-C-N ceramics

Journal	Journal of the European Ceramic Society
ISSN	09552219
Open Access	No