Computational parametric study for plastic strain localization and fracture in a polycrystalline material with a porous ceramic coating
TL;DR: In this paper, the effects of the substrate grain size, the curvature of the coati cation, and the substrate curvature on polysilazane-based ceramic coatings have been analyzed.
Abstract: Polysilazane-based ceramic coatings have ever-increasing applications in critical and high-power engineering. This paper analyzes the effects of the substrate grain size, the curvature of the coati...
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TL;DR: In this paper , the analysis of local stress fields and effective orientation-dependant elastic properties was performed for additively manufactured stainless steel using uni-and bidirectional scanning, and the relationship between the process-induced microstructure and the anisotropic elastic response was discussed.
5 citations
TL;DR: Zinoviev et al. as discussed by the authors investigated the effect of pore distribution, size, number, and distance between them on the local stress-strain state of a porosity-free coating.
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TL;DR: An overview of the phase-field method for modeling solidification is presented, together with several example results as mentioned in this paper, which has been applied to a wide variety of problems including dendritic, eutectic, and peritectic growth in alloys; and solute trapping during rapid solidification.
Abstract: ▪ Abstract An overview of the phase-field method for modeling solidification is presented, together with several example results. Using a phase-field variable and a corresponding governing equation to describe the state (solid or liquid) in a material as a function of position and time, the diffusion equations for heat and solute can be solved without tracking the liquid-solid interface. The interfacial regions between liquid and solid involve smooth but highly localized variations of the phase-field variable. The method has been applied to a wide variety of problems including dendritic growth in pure materials; dendritic, eutectic, and peritectic growth in alloys; and solute trapping during rapid solidification.
1,431 citations
TL;DR: In this paper, the authors highlight the following scientific issues related to advanced polymer-derived ceramics research: (1) General synthesis procedures to produce silicon-based preceramic polymers.
Abstract: Preceramic polymers were proposed over 30 years ago as precursors for the fabrication of mainly Si-based advanced ceramics, generally denoted as polymer-derived ceramics (PDCs). The polymer to ceramic transformation process enabled significant technological breakthroughs in ceramic science and technology, such as the development of ceramic fibers, coatings, or ceramics stable at ultrahigh temperatures (up to 2000°C) with respect to decomposition, crystallization, phase separation, and creep. In recent years, several important advances have been achieved such as the discovery of a variety of functional properties associated with PDCs. Moreover, novel insights into their structure at the nanoscale level have contributed to the fundamental understanding of the various useful and unique features of PDCs related to their high chemical durability or high creep resistance or semiconducting behavior. From the processing point of view, preceramic polymers have been used as reactive binders to produce technical ceramics, they have been manipulated to allow for the formation of ordered pores in the meso-range, they have been tested for joining advanced ceramic components, and have been processed into bulk or macroporous components. Consequently, possible fields of applications of PDCs have been extended significantly by the recent research and development activities. Several key engineering fields suitable for application of PDCs include high-temperature-resistant materials (energy materials, automotive, aerospace, etc.), hard materials, chemical engineering (catalyst support, food- and biotechnology, etc.), or functional materials in electrical engineering as well as in micro/nanoelectronics. The science and technological development of PDCs are highly interdisciplinary, at the forefront of micro- and nanoscience and technology, with expertise provided by chemists, physicists, mineralogists, and materials scientists, and engineers. Moreover, several specialized industries have already commercialized components based on PDCs, and the production and availability of the precursors used has dramatically increased over the past few years. In this feature article, we highlight the following scientific issues related to advanced PDCs research: (1) General synthesis procedures to produce silicon-based preceramic polymers.
(2) Special microstructural features of PDCs.
(3) Unusual materials properties of PDCs, that are related to their unique nanosized microstructure that makes preceramic polymers of great and topical interest to researchers across a wide spectrum of disciplines.
(4) Processing strategies to fabricate ceramic components from preceramic polymers.
(5) Discussion and presentation of several examples of possible real-life applications that take advantage of the special characteristics of preceramic polymers. Note: In the past, a wide range of specialized international symposia have been devoted to PDCs, in particular organized by the American Ceramic Society, the European Materials Society, and the Materials Research Society. Most of the reviews available on PDCs are either not up to date or deal with only a subset of preceramic polymers and ceramics (e.g., silazanes to produce SiCN-based ceramics). Thus, this review is focused on a large number of novel data and developments, and contains materials from the literature but also from sources that are not widely available.
1,410 citations
TL;DR: In this paper, a Monte Carlo procedure is applied to the study of grain growth in two dimensions, where the initial distribution of orientations is chosen at random and the system evolves so as to reduce the number of nearest neighbor pairs of unlike crystallographic orientation.
918 citations
TL;DR: In this article, a new approach to the modelling of grain structure formation in solidification processes is proposed based upon a two-dimensional cellular automata technique, the model includes the mechanisms of heterogeneous nucleation and of grain growth.
Abstract: A new approach to the modelling of grain structure formation in solidification processes is proposed. Based upon a two-dimensional cellular automata technique, the model includes the mechanisms of heterogeneous nucleation and of grain growth. Nucleation occurring at the mould wall as well as in the liquid metal are treated by using two distributions of nucleation sites. The location and the crystallographic orientation of the grains are chosen randomly among a large number of cells and a certain number of orientation classes, respectively. The growth kinetics of the dendrite tip and the preferential 〈100〉 growth directions of cubic metals are taken into account. The model is then applied to small specimens of uniform temperature. The columnar-to-equiaxed transition, the selection and extension of columnar grains which occur in the columnar zone and the impingement of equiaxed grains are clearly shown by this technique. The calculated effect of the alloy concentration and cooling rate upon the resultant microstructure agree with experimental observations.
785 citations
TL;DR: In this paper, a theory of damage mechanics for brittle porous solids in multiaxial compression is proposed. But the model is restricted to the case of glass and is not suitable for brittle materials.
499 citations