Abstract
Polycrystalline ceramics, such as alumina (Al2O3), are brittle and they generally wear by fracture mechanism, which limits their potential in tribological applications. In the present work, computational design tools are used to develop hybrid Al2O3 composites reinforced with best combinations of toughening and self-lubricating second-phase particles for cutting tool inserts in dry machining applications. A mean-field homogenization approach and J-integral based fracture toughness models are employed to predict the effective structural properties (such as elastic modulus and fracture toughness) and related to the intrinsic attributes of second- phase inclusions in Al2O3 matrix. Silicon carbide (SiC), boron nitride (cBN and hBN), zirconia (ZrO2), graphite, titanium dioxide (TiO2), and titanium carbide (TiC) were found the most suitable candidates to be added in Al2O3 matrix as individual or hybrid combinations. A series of samples including standalone Al2O3, single inclusion composites (Al2O3/SiC, Al2O3/cBN) and hybrid composites (Al2O3/SiC/cBN, Al2O3/SiC/TiO2 and Al2O3/SiC/graphite) are sintered by Spark Plasma Sintering (SPS) for validation purpose. Properties of the sintered composites are measured and compared with the proposed computational material design. Composition and phase transformation of the sintered samples are studied using X-ray diffraction (XRD) and Raman spectroscopy, while their morphology is studied using Field Emission Scanning Electron Microscope (FESEM). The presented nontraditional material design approach is found to significantly reduce experimental time and cost of materials in developing toughened and anti-friction ceramic composites.
Highlights
The global drive of innovation has led to the manufacturing of complex high-quality products in various technological areas
The major focus is on the key structural target properties namely, elastic modulus and fracture toughness, which is considered as a constraint on the design process with self-lubrication characteristics
After predicting the effective elastic modulus of Al2 O3 composites with Silicon carbide (SiC) and other second-phase, we have found that 20% Cubic Boron Nitride (cBN), 10% TiO2 or 5% graphite mixed with at least 20% of SiC in Al2 O3 would give the best combinations in terms of intended properties
Summary
The global drive of innovation has led to the manufacturing of complex high-quality products in various technological areas. This in turn has raised the need for cost efficient production which has raised research interest within the industry for enhanced cutting tool material design [1]. As dry cutting becomes an increasingly favored process, this requires cutting tools to maintain structural properties such as fracture toughness at high temperatures [2,3]. Materials 2019, 12, 2378 cheaper alternative to regular cutting tools as only the insert needs to be replaced which saves money and time. Materials commonly considered as inserts for hard work pieces include ceramics
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