Multifunctional Polymer Composites for "Intellectual" Structures: Present State, Problems, Future

2008 ◽  
Vol 47-50 ◽  
pp. 81-84
Author(s):  
Anatoliy T. Ponomarenko ◽  
Oleg Figovsky ◽  
Vitaliy G. Shevchenko
Keyword(s):  
Physical Properties ◽  
Heterogeneous Systems ◽  
Hierarchical Structures ◽  
Ceramic Matrix Composites ◽  
Matrix Composites ◽  
Technological Parameters ◽  
Inhomogeneous Materials ◽  
Intelligent Structures ◽  
Superconducting Ceramics ◽  
Methods Of Synthesis

Strategy of the synthesis of multifunctional materials is developed on the basis of physical properties of composites, composition of fillers, the type of polymer matrix and distribution of ingredients in composite. Each of these factors is displayed in material in different extent depending on technological parameters of processing, and also properties and interaction of fillers in particular conditions. In homogeneous and, in particular in heterogeneous systems, such as metals and alloys, ferro - and ferrimagnetics, ferroelectrics, ferroelectromagnetics, polymer and ceramic matrix composites, high-temperature superconducting ceramics, etc. It is always possible to outline various types of hierarchy. Investigation of the effect of hierarchical structures on physical properties and the nature of interaction of various internal fields in inhomogeneous materials is inseparably linked with the development of methods of synthesis of new smart and intelligent structures.

Multilayered Fiber-Reinforced Oxide Composites Produced by Lamination of Thermoplastic Prepregs

2014 ◽  
Vol 89 ◽  
pp. 145-150 ◽  
Author(s):  
Paula O. Guglielmi ◽  
Diego Blaese ◽  
Murilo Hablitzel ◽  
Gabriel Nunes ◽  
Victor R. Lauth ◽  
...  
Keyword(s):  
Bending Strength ◽  
Mechanical Performance ◽  
Hierarchical Structures ◽  
Ceramic Matrix Composites ◽  
Organic Matrix ◽  
Ceramic Composites ◽  
Processing Route ◽  
Failure Behavior ◽  
Matrix Composites ◽  
Fiber Reinforced

For advanced ceramic composites, affordable manufacturing is still the most essential shortcoming with respect to successful commercial use. This holds particularly for components made out of composites with complex hierarchical structures and high demands of mechanical performance and reliability at the same time, e.g. fiber-reinforced ceramic matrix composites (FRCMCs). Therefore, a new processing route is presented here, which is based on the lamination of thermoplastic prepregs. This route allows not only affordable manufacturing, but also advanced mechanical reliability. Powder metallurgy techniques are combined here with concepts from the prepreg technology in a route consisting of the following steps (a) manufacturing of 2 D prepregs using commercial fiber fabrics which are infiltrated with compounds of ceramic particles embedded in an organic matrix, (b) followed by respective stacking and joining, (c) burn out of the organic matrix and (d) sintering to consolidate the matrix. Composites consisting of a porous Al2O3/ZrO2 matrix, reinforced by 8 layers of NextelTM 610 fiber fabric exhibit a bending strength of ~440 MPa, with graceful failure behavior, e.g. a stepwise stress reduction after peak nominal stress. The fracture of these composites is controlled by a series of interfacial delamination events, which enhance energy dissipation during failure.

scholarly journals Toughening materials: enhancing resistance to fracture

2021 ◽  
Vol 379 (2203) ◽  
pp. 20200437
Author(s):  
Robert O. Ritchie
Keyword(s):  
Mechanical Properties ◽  
Fracture Resistance ◽  
Structural Damage ◽  
Crack Tip ◽  
Hierarchical Structures ◽  
Ceramic Matrix Composites ◽  
Matrix Composites ◽  
High Entropy ◽  
Synthetic Materials ◽  
Structural Adaptability

It has been said that ‘God invented plasticity, but the Devil invented fracture!’ Both mechanisms represent the two prime modes of structural failure, respectively, plastic collapse and the rupture/breaking of a component, but the concept of developing materials with enhanced resistance to fracture can be difficult. This is because fracture resistance invariably involves a compromise—between strength and ductility, between strength and toughness—fundamentally leading to a ‘conflict’ between nano-/micro-structural damage and the mechanisms of toughening. Here, we examine the two major classes of such toughening: (i)  intrinsic toughening , which occurs ahead of a crack tip and is motivated by plasticity—this is the principal mode of fracture resistance in ductile materials, and (ii) extrinsic toughening , which occurs at, or in the wake of, a crack tip and is associated with crack-tip shielding—this is generally the sole mode of fracture resistance in brittle materials. We briefly examine how these distinct mechanistic processes have been used to toughen synthetic materials—intrinsically in gradient materials and in multiple principal-element metallic alloys with the example of metallic glasses and high-entropy alloys, and extrinsically in ceramics with the example of ceramic-matrix composites—in comparison to Nature which has been especially adept in creating biological/natural materials which are toughened by one or both mechanistic classes, despite often consisting of constituents with meagre mechanical properties. The success of Nature has been driven by its ability to cultivate the development of materials with multiple length-scale hierarchical structures that display ingenious gradients and structural adaptability, a philosophy which we need to emulate and more importantly learn to synthesize to make structural materials of the future with unprecedented combinations of mechanical properties. This article is part of a discussion meeting issue ‘A cracking approach to inventing new tough materials: fracture stranger than friction’.

Investigation of gas-phase processes for the preparation of fiber-reinforced organomorphic ceramic composites with a SiC-matrix

2020 ◽  
pp. 23-30
Author(s):  
E. A. Bogachev ◽  
V. I. Kulik ◽  
A. V. Kulik ◽  
A. S. Nilov
Keyword(s):  
Gas Phase ◽  
Numerical Study ◽  
Chemical Deposition ◽  
Ceramic Matrix Composites ◽  
Ceramic Composites ◽  
Matrix Composites ◽  
Technological Parameters ◽  
1D Model ◽  
Fiber Preforms ◽  
Uniform Pore Size

The isothermal process of gas-phase chemical deposition for the compaction of organomorphic carbon-fiber preforms with a SiC-matrix obtained by carbonization of compressed fibers of oxidized polyacrylonitrile has been investigated. Their feature is high (up to 70 %) and uniform pore size (reduced pore diameter from several micrometers to several tens of micrometers) porosity. The problem of optimizing the technological parameters of the process of obtaining ceramic-matrix composites (CMC) was solved by a combination of experimental research and numerical modeling. Experimental samples of CMC were obtained using a non-halogen precursor of methylsilane CH3SiH3, and their residual porosity was determined. For the numerical study of the gas-phase process of compaction of preforms, a 1D model was used. The simulation results were compared with experimental observations.

A TEM investigation of silicon nitride whiskers

1987 ◽  
Vol 45 ◽  
pp. 160-161
Author(s):  
Tapan Roy
Keyword(s):  
Silicon Nitride ◽  
High Resolution ◽  
Ceramic Matrix Composites ◽  
High Resolution Electron Microscopy ◽  
Molten Silicon ◽  
Matrix Composites ◽  
Ceramic Fibers ◽  
Resolution Electron ◽  
Point To Point ◽  
Technological University

Ceramic fibers are being used to improve the mechanical properties of metal matrix and ceramic matrix composites. This paper reports a study of the structural and other microstructural characteristics of silicon nitride whiskers using both conventional TEM and high resolution electron microscopy.The whiskers were grown by T. E. Scott of Michigan Technological University, by passing nitrogen over molten silicon in the presence of a catalyst. The whiskers were ultrasonically dispersed in chloroform and picked up on holey carbon grids. The diameter of some whiskers (<70nm) was small enough to allow direct observation without thinning. Conventional TEM was performed on a Philips EM400T while high resolution imaging was done on a JEOL 200CX microscope with a point to point resolution of 0.23nm.

Quality analysis and prospects for use of lupin seeds of Belarusian selection

2020 ◽  
Vol 3 (1) ◽  
pp. 22
Author(s):  
Lyudmila Rukshan ◽  
Alena Navazhilova ◽  
Dmitry Kudin
Keyword(s):  
Chemical Composition ◽  
Physical Properties ◽  
Wheat Flour ◽  
Great Influence ◽  
Quality Analysis ◽  
Bakery Products ◽  
Whole Grain ◽  
Technological Parameters ◽  
Protein Food ◽  
Lupin Seeds

The paper investigates technological parameters of the quality of low-alkaloid lupin of five cultivars selected and grown in the Republic of Belarus during the years from 2007 to 2017. Prospects for the use of the obtained seeds have been studied. This study reveals great influence of cultivar and climatic conditions during growth of lupin seeds on correlation of anatomic parts in seeds as well as on their physical properties. Cultivar of lupin seeds Jan is recommended for whole grain flour and graded flour production based on its anatomic composition, uniformity and physical properties. A comparative analysis of chemical composition, quality parameters and technological properties of lupin flour has been done. The chemical composition of lupin flour, of whole grain lupin flour, in particular, has been found to be relatively low in starch, high in protein, food fibers, minerals and organic acids. As a result, whole grain lupin flour has been proved to have higher food value when compared to traditional wheat flour. This paper demonstrates the difference between lupin flour characteristics and those of wheat flour in terms of color, acidity, enzymatic activity and adsorbing properties. This study reveals the possibility of use of lupin flour in bakery products by substituting traditional types of flour with lupin flour at 10-30% levels, as well as by replacing egg products with lupin flour at 25-50% levels. The work highlights the use of lupin flour at the stages of dough kneading, dough preparation, foam and emulsion production mainly by using rapid dough making methods.Practical applicationsRecommendations have been made on the usage of lupin flour in the technological process of bakery products manufacturing, macaroni and flour confectionery products production.

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