Influence of diamond particles content on the critical load for crack initiation and fracture toughness of SiOC glass–diamond composites (original) (raw)
Related papers
Journal of Applied Physics, 1995
The fracture behavior of synthetic diamond has been investigated using indentation methods and by the tensile testing of pre-notched fracture-mechanics type samples. Specifically, the fracture toughness of free-standing diamond plates, grown by chemically-vapor deposited (CVD) methods, was measured using Vickers indentations and by the use of disk-shaped compact-tension specimens; the latter method provides an evaluation of the through-thickness fracture properties, whereas the indentation method was performed on the nucleation surface of the sample. Measured fracture toughness (K,) values were found to be approximately 5-6 MPaJm by both methods, indicating that the fracture resistance of CVD diamond does not vary appreciably with grain size (within the certainty of the testing procedures). Complications, however, arose with the fracture-mechanics testing regarding crack initiation from a relatively blunt notch; further work is needed to develop pre-cracking methods to permit more reliable fracture toughness testing of diamond. 0 1995 American Institute of Physics.
International Journal of Refractory Metals & Hard Materials, 2016
Fracture experiments in a notched semi-circular bend configuration were conducted to characterize rate effects and failure micromechanisms of a marble using a servo-hydraulic machine and a modified split Hopkinson pressure bar. Three real-time measurement techniques were used to estimate crack propagation velocities and full-field deformation fields. Micro-measurement techniques were employed to qualitatively and quantitatively identify micrograph and surface morphology. Based on the theory of fracture mechanics, a micromechanical model was presented to examine the intergranular and transgranular fracture. The results indicated that fracture toughness and surface roughness were dependent on loading rate, which were induced by the intrinsic failure mechanisms.
Mechanical Properties of Epoxy Composites with Low Content of Diamond Particles
Diamond-epoxy composites reinforced with low content of submicron diamond powder 0.1, 0.4, 0.7, and 1.0 wt % were synthesized. As received diamond powder was acid treated to purify and functionalize diamond particles. Fourier Transform Infrared Spectroscopy was utilized to study the moieties attached to the diamond particles. The trace elemental analysis of impurities in diamond powder before and after acid treatment was performed using ion beam techniques. The mechanical properties of the epoxy matrix were enhanced with the addition of purified and functionalized diamond powder. The Dynamical mechanical analysis results revealed that storage modulus of the prepared composites has been increased by similar to 100% with diamond loading of 0.7 wt %. The Vickers's hardness of the diamond-epoxy composite was similar to 39% higher than that of pure epoxy for the loading of 1.0 wt % diamond powder. Mechanisms responsible for the enhancement of the mechanical properties are discussed. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Fracture toughness evaluation of polycrystalline diamond as a function of microstructure
Engineering Fracture Mechanics, 2015
The fracture toughness of polycrystalline diamond has been investigated with reference to the microstructure. The physical interpretation of the critical distance is examined, and it is illustrated that this becomes increasingly difficult to define for larger grain sizes. Consequently, the minimum notch root radius becomes an important parameter governing the accuracy of toughness for blunt notched specimens. A higher than expected toughness was observed for fine grain specimens, illustrating the influence of the combination of both intrinsic and extrinsic fracture mechanisms on the overall toughness. Finally, the process of cobalt removal was found to reduce toughness compared to conventional grades.
Microstructural Characterisation and Wear Behaviour of Diamond Composite Materials
Materials, 2010
Since the initial research leading to the production of diamond composite materials, there have been several important developments leading to significant improvements in the properties of these superhard composite materials. Apart from the fact that diamonds, whether originating from natural resources or synthesised commercially, are the hardest and most wear-resistant materials commonly available, there are other mechanical properties that limit their industrial application. These include the low fracture toughness and low impact strength of diamond. By incorporating a range of binder phases into the sintering production process of these composites, these critically important properties have been radically improved. These new composites can withstand much higher operating temperatures without markedly reducing their strength and wear resistance. Further innovative steps are now being made to improve the properties of diamond composites by reducing grain and particle sizes into the nano range. This review will cover recent developments in diamond composite materials with special emphasis on microstructural characterisation. The results of such studies should assist in the design of new, innovative diamond tools as well as leading to radical improvements in the productivity of cutting, drilling and sawing operations in the exploration, mining, civil construction and manufacturing industries.
Diamond and Related Materials, 2009
The effects of thermal annealing and Si incorporation on the structure and properties of diamond-like carbon (DLC) films were investigated. As-deposited DLC film (DLC) and Si incorporated DLC film (Si-DLC), both with and without thermal annealing, were analyzed for bonding structure, residual stress, film thickness, elastic modulus and fracture properties using Raman spectroscopy, wafer curvature, nanoindentation, four-point bend fracture testing, and X-ray photoelectron spectroscopy (XPS). Raman spectroscopy clearly showed that thermal annealing of DLC films promotes more sp 2 bonding character, whereas Si incorporation into the films promotes more sp 3 bonding character. Interfacial fracture energies, film hardness and elastic modulus, and residual film stress were all found to vary strongly with the degree of sp 3 bonding in the DLC film. These changes in mechanical properties are rationalized in terms of the degree of three dimensional inter-links within the atomic bond network.
In this work, the authors report the mechanical properties of three emerging materials in thin film form: single crystal silicon carbide ͑3C-SiC͒, ultrananocrystalline diamond, and hydrogen-free tetrahedral amorphous carbon. The materials are being employed in micro-and nanoelectromechanical systems. Several reports addressed some of the mechanical properties of these materials but they are based in different experimental approaches. Here, they use a single testing method, the membrane deflection experiment, to compare these materials' Young's moduli, characteristic strengths, fracture toughnesses, and theoretical strengths. Furthermore, they analyze the applicability of Weibull theory ͓Proc. Royal Swedish Inst. Eng. Res. 153, 1 ͑1939͒; ASME J. Appl. Mech. 18, 293 ͑1951͔͒ in the prediction of these materials' failure and document the volumeor surface-initiated failure modes by fractographic analysis. The findings are of particular relevance to the selection of micro-and nanoelectromechanical systems materials for various applications of interest.
Technical Characteristics of Diamond Reinforced Epoxy Composites
2005
Diamond reinforced polymeric composites are becoming ever more applied in wear resistant tools. The performance of these composites depends on their mechanical properties in association with the hard diamond particle interaction with the soft polymeric matrix. In the present work, epoxy matrix composites, with different phr, reinforced with 10, 20 and 30 wt.% diamond particles were investigated through mechanical tests and scanning electron microscopy observation. The results have shown that the phr 17 epoxy is significantly stronger than the stoichiometric phr 13. Moreover, the strength of the composite is decreased with the amount of incorporated diamond. By contrast, the larger the percentage of diamond particles, the more wear resistant become the composites. These results are discussed in terms of the structural characteristics of the composites.
The indentation fracture toughness (KC) and its parameters: the case of silica-rich glasses
Journal of Non-Crystalline Solids, 2004
The fracture toughness of several glasses, including soda-lime-silica and aluminosilicate glasses, was measured by both the indentation fracture (IF) and the single-edge notched beam (SENB) techniques. The flow densification mechanism occurring during indentation for silica-rich compositions leads to discrepancies between the two methods. The influence of the indentation load and the post-indentation fatigue duration on the indentation on the crack length and on the fracture toughness measurement were investigated. Fatigue curves (V-K) were obtained directly from indentation experiments and fatigue parameters were derived. The sub-critical crack growth resistance was found to be improved by increasing the silica content. In comparison with the studied oxide glasses, a Y-SiAlON oxynitride glass exhibits much greater fatigue resistance. The fatigue phenomenon has a major effect on the estimation of K C from indentation-cracking measurements.
Atomistic modeling of the fracture of polycrystalline diamond
Physical Review B, 2000
A series of molecular-dynamics simulations using a many-body interatomic potential has been performed to investigate the behavior under load of several ͗001͘ and ͗011͘ symmetrical tilt grain boundaries ͑GB's͒ in diamond. Cohesive energies, the work for fracture, maximum stresses and strains, and toughness as a function of GB type are evaluated. Results indicate that special short-period GB's possess higher strengths and greater resistance to crack propagation than GB's in nearby misorientation angles. Based on dynamic simulations, it was found that the mechanism of interface failure for GB's without preexisting flaws is not that implied by Orovan's criterion, but rather GB strength is defined by GB type instead of cleavage energy. In simulations of crack propagation within GB's on the other hand, it was found that critical stresses for crack propagation from atomistic simulation and from the Griffith criterion are consistent, indicating that GB cleavage energy is an important characteristic of GB toughness. Crack propagation in polycrystalline diamond samples under an applied load was also simulated and found to be predominantly transgranular rather than intergranular.