Multi Material Research Articles

Crystal chemistry of sodium zirconium phosphate based simulated ceramic waste forms of effluent cations (Ba 2+, Sn 4+, Fe 3+, Cr 3+, Ni 2+ and Si 4+) from light water reactor fuel reprocessing plants

A novel concept of immobilization of light water reactor (LWR) fuel reprocessing waste effluent through interaction with sodium zirconium phosphate (NZP) has been established. Such conversion utilizes waste materials like zirconium and nickel alloys, stainless steel, spent solvent tri-butyl phosphate and concentrated solution of NaNO 3. The resultant multi component NZP material is a physically and chemically stable single phase crystalline product having good mechanical strength. The NZP matrix can also incorporate all types of fission product cations in a stable crystalline lattice structure; therefore, the resultant solid solutions deserve quantification of crystallographic data. In this communication, crystal chemistry of the two types of simulated waste forms (type I—Na 1.49Zr 1.56Sn 0.02Fe 0. 28Cr 0.07Ni 0.07P 3O 12 and type II—Na 1.35Ba 0.14Zr 1.56Sn 0.02Fe 0. 28Cr 0.07Ni 0.07P 2.86Si 0.14O 12) has been investigated using General Structure Analysis System (GSAS) programming of the X-ray powder diffraction data. About 4001 data points of each have been subjected to Rietveld analysis to arrive at a satisfactory structural convergence of Rietveld parameters; R-pattern ( R p) = 0.0821, R-weighted pattern ( R wp) = 0.1266 for type I and R p = 0.0686, R wp = 0.0910 for type II. The structure of type I and type II waste forms consist of ZrO 6 octahedra and PO 4 tetrahedra linked by the corners to form a three-dimensional network. Each phosphate group is on a two-fold rotation axis and is linked to four ZrO 6 octahedra while zirconium octahedra lies on a three-fold rotation axis and is connected to six PO 4 tetrahedra. Though the expansion along c-axis and shrinkage along a-axis with slight distortion of bond angles in the synthesized crystal indicate the flexibility of the structure, the waste forms are basically of NZP structure. Morphological examination by SEM reveals that the size of almost rectangular parallelepiped crystallites varies between 0.5 and 1.5 μm. The EDX analysis provides the analytical evidence of immobilization of effluent cations in the matrix. The particle size distributions of the material along selected reflecting planes have been calculated by Scherrer's formula.

Editorial for the special issue of IJAMT on multi material microsystem manufacturing

Editorial for the special issue of IJAMT on multi material microsystem manufacturing

Automated Semi-Solid Forging of Steel Components by Means of Thixojoining

The thixoforming processes join the advantages of conventional forming technologies as forging and casting in respect of the mechanical properties and the practicable geometries. Within the framework of the Collaborative Research Centre 289 at the RWTH Aachen University intensive investigations on semi-solid processing with some steel grades have been running. For this purpose an automated thixoforging plant (thixo-cell) has been developed in a closed cooperation with several industrial partners. With this equipment multi material demonstrator components have been successfully produced by thixojoining using semi-solid X210CrW12 tool steel.

Multi phase field model for solid state transformation with elastic strain

A multi phase field model is presented for the investigation of the effect of transformation strain on the transformation kinetics, morphology and thermodynamic stability in multi phase materials. The model conserves homogeneity of stress in the diffuse interface between elastically inhomogeneous phases, in which respect it differs from previous models. The model is formulated consistently with the multi phase field model for diffusional and surface driven phase transitions [I. Steinbach, F. Pezzolla, B. Nestler, M. Seeßelberg, R. Prieler, G.J. Schmitz, J.L.L. Rezende, A phase field concept for multiphase systems, Physica D 94 (1996) 135–147; J. Tiaden, B. Nestler, H.J. Diepers, I. Steinbach, The multiphase-field model with an integrated concept for modeling solute diffusion, Physica D 115 (1998) 73–86; I. Steinbach, F. Pezzolla, A generalized field method for multiphase transformations using interface fields, Physica D 134 (1999) 385] and gives a consistent description of interfacial tension, multi phase thermodynamics and elastic stress balance in multiple junctions between an arbitrary number of grains and phases. Some aspects of the model are demonstrated with respect to numerical accuracy and the relation between transformation strain, external stress and thermodynamic equilibrium.

Some features associated with organosilane groups grafted by the sol–gel process onto synthetic talc-like phyllosilicate

Two new lamellar inorganic–organic magnesium silicates have been successfully synthesized by using sol–gel based processes under mild temperature conditions. The talc-organosilicates derived using two silylating agents as the silicon source, (i) 3-chloropropyltrimethoxysilane, and (ii) from the attachment of 5-amino-1,3,4-thiadiazole-2-thiol molecule to this precursor agent, yielded PhMg-Cl and PhMg-Tz phyllosilicates. These organoclays were characterized through elemental analyses, infrared spectroscopy, X-ray diffractometry, surface area, thermogravimetry, and carbon and silicon solid state nuclear magnetic resonance spectroscopy. The results confirmed the presence of organic moieties covalently bonded to the inorganic silicon sheet network of the 2:1 class of phyllosilicates, with a density of organic molecules of 6.6 ± 0.1 and 2.7 ± 0.2 mmol g −1 anchored on the inorganic layer and with interlayer distances of 1158 and 1628 pm, respectively. The nuclear magnetic resonances results in the solid state are in agreement with the sequence of carbons distributed in the pendant chains of the original silylating agents and the silicon bonded to oxygen atoms or carbon atoms of the inorganic sheets, as expected for the organically functionalized phyllosilicates. The enhanced potential of the new compound PhMg-Tz as a multi property material was explored in adsorbing cations from aqueous solution. The basic sulfur and nitrogen centers attached to the pendant chains inside the lamellar cavity can coordinate mercury, by presenting an isotherm saturated at 0.19 mmol g −1 of this heavy metal. The functionality of this organoclay-like material expresses its potential for heavy cation removal from an ecosystem.

Studies of polyethylene multi layer films used as greenhouse covers under Saharan climatic conditions

The behavior with regard to abrasion of a new generation of polymeric greenhouse covers presenting a sandwich structure made of three layers, one EVA19 layer inserted between two low density polyethylene layers, has been studied. Optical, thermal, surface analysis and mechanical properties have been analyzed on samples having undergone different thermal treatments associated with sand and wind simulation in order to test their performance when used in a Saharan environment. The data analysis is performed by comparing these results with those obtained on a monolayer polyethylene film often used in Algeria for plasticulture devices. The performance of these new multi layers materials is found better than that obtained for the mono layer film, with regard to the mechanical, the optical properties and resistance to the abrasion effect due to sand/wind.

The Application of ODF Analysis for Drawing Sheet of Weak Textured Materials

For multi crystal materials, particularly multi-crystal metallic materials, it is unavoidable to make its crystal orientation change during the process. For instance, improving the property of soft magnetic materials should rely on the Cubic texture {100} <001>, but the property of the deep-draw sheet materials is closely related to its texture. Besides the material's composition, the crystal and the microstructure, the texture also takes a very important role in the properties of the materials [1, 2]. The positive pole figure analytic method is comparatively simple and intuitional. This is unquestionable in the texture analysis of cold-rolled samples, as in drawing sheet materials. It shows that the material orientation of isotropy or multiple weak textured materials is coexistent. The ODF analysis can be a good method for resolving this. In the study, the serial ODF analysis is used to analyze the property of nickel based alloys of drawing sheet materials considering different deformation amount, annealing temperature and annealing time in layers. In practice, it can be applied to production techniques.

Synthesis and Structure of the First Stannadisiloxanediol: [Me2N(CH2)2]2Sn(OSit‐Bu2OH)2. A Potential Precursor for the Preparation of Multi Component Oxides

AbstractThe synthesis of [Me2N(CH2)2]2Sn(OSit‐Bu2OH)2 (1) by the base‐assisted cohydrolysis of [Me2N(CH2)2]2SnCl2 and t‐Bu2SiCl2 is described. The molecular structure of 1, determined by single crystal X‐ray diffraction analysis, features a pentacoordinated tin atom owing to the intramolecular coordination of the nitrogen atom of one 3‐dimethylaminopropyl group, and reveals both intramolecular Si(Sn)O···H‐O and intermolecular N···H‐O hydrogen bonding. Compound 1 is a rare example of a metallasiloxanol and holds potential for the preparation of multi component oxide materials.

Tool path generation of multi‐material assembly for rapid manufacture

Tool path generation is the key procedure to fabricate multi‐material (MM) assemblies in rapid prototyping (RP) machines. In slicing MM assembly, there will be 2D regions of different materials. The regions need to be filled into 2.5D slabs. In order to complete all regions in a certain slice faster, tool holders should fill the regions simultaneously. In other words, the tool holders will move around in the RP work envelope concurrently. In such case, interference between tool holders may occur. Therefore, collision‐free path plan should be generated. In this paper, a dexel based spatio‐temporal modelling approach is proposed for detecting collision in rapid manufacturing MM assemblies. The approach is based on 2D regions in dexel representation, which needs only simple computation. As a result, tool holders can fill MM regions simultaneously and efficiently.

Simulation of airbag inflation processes using a coupled fluid structure approach

This paper explores simulation techniques for airbag inflation problems using a coupled fluid structure approach. It is to be seen as an initial study on the phenomena occurring in an airbag during a so called out of position occupant impact. The problem studied in this paper is an airbag which is set to impact a head form. The head form is positioned at a very short distance from the airbag. A multi material arbitrary Lagrangian Eulerian technique in the explicit finite element code LS-DYNA is used for the fluid and it is coupled to the structure using a penalty based fluid structure contact algorithm. The results for the head form acceleration and velocity show a good agreement to experimentally obtained values. At the early stages of the inflation process a high pressure zone is found to develop between the gas inlet and the head form. Consequently the pressure difference between the inlet and the high pressure zone is too low for an a priori assumption of sonic flow at the inlet, which is a common requirement in the control volume models used in the industry today.

Dexel-Based Direct Slicing of Multi-Material Assemblies

Slicing is an important procedure in rapid prototyping (RP) pre-processing, and can be grouped into two categories: direct slicing and adaptive slicing. At present, investigations into the use of both direct and adaptive slicing methods are taking place. However, not many direct slicing approaches have been reported in the literature. The methods are also restricted to some solids in CSG or some CAD systems. Also, approaches on adaptive slicing are too complicated. The method proposed in this paper employs dexel encoding for direct slicing multi-material (MM) assemblies in RP. One advantage of using a dexel model is that Boolean operations can be performed simply on 1D line segments. Dexels can also be easily converted to tool paths in RP machines. Compared to the ray representation of CSG trees, dexel models can be extended to represent MM assemblies with material properties. Therefore, the method has high potential for direct slicing. In this paper, traditional dexel models are first extended for rapid manufacturing single solid and MM assemblies. Compared to other adaptive slicing approaches, a much more efficient and simple dexel model, for adaptive refinement in the building direction is then developed. To further improve the surface finish, a layerwise refinement approach is also discussed. Finally, the computational complexity of the proposed method is studied.

Thermal properties of multiphase polymeric materials and dynamic methods for their characterization

The thermal conductivity, diffusivity and specific heat of multi phase polymeric materials such as polystyrene and polymethylmethacrylate are reported. With emphasis on the thermal properties of such materials, a variety of implementation and classification regarding heat conduction will be highlighted. These properties were measured using dynamic methods namely; the transient plane source named also Gustafsson probe (TPS), the dynamic plane source (DPS) and the pulse transient technique (PTT), for measurements of thermal effusivity, thermal conductivity, thermal diffusivity and specific heat of solids One of the advantages considering these techniques is the possibility to extract all thermophysical parameters, the thermal conductivity, thermal diffusivity and specific heat from one single transient recording. Dynamic methods use a probe that is technically a resistive element, as the heat source. The first two TPS and DPS employ this probe as both heat source and temperature sensor. The later method PTT, for temperature sensing, uses a thermocouple placed apart of the heat source. A description of the main features and the principles on which these methods are based will be highlighted.

Improvement Of The Parametric Fire Of Eurocode 1 Based On Experimental Test Results

The basic equations, the limitations and the main features of the parametric fire proposed in Annexe B of Eurocode 1 are given. 48 experimental fire tests are used to assess the validity of this model. The model has been applied to these tests and the comparison has been made, for each test, on the maximum temperature in the air and on the maximum temperature calculated in 2 hypothetical steel sections, one thermally protected and one unprotected. The agreement is very poor for the air and for the unprotected steel temperature, and somewhat better for the protected steel temperature. Some proposals are made which allow to improve the agreement, while keeping the same expressions for the parametric fire. These modifications concern the equivalent thermal properties of multi material walls, and the introduction of a minimum duration of the fire and a of a ventilation effect in case of fuel-bed controlled fires.

Future Direct Manufacturing of Metal Parts with Free-Form Fabrication*

In this paper manufacturing of metal parts with Free Form Fabrication, FFF is discussed. Thoughts and ideas has been inspired by the Theory of Inventive Problem Solving, TIPS. Principles and effects based on work by Altshuller has been combined with knowledge on FFF. The time frame has been limited to what is likely to be achieved within the next two years. Some promising ideas are the introduction of vibration and the use of multi phase materials.

Antibacterial, Deodorizing, and UV Absorbing Materials Obtained with Zinc Oxide (ZnO) Coated Fabrics

Ultra fine particle zinc oxide from Sumitomo Cement Co. is a multi functional material with antibacterial, deodorizing, and UV absorbing properties. The company has dispersed ultra fine zinc oxide into various types of vehicles that are classified into water-based and organic solvent-based types.

Latest Developments in the Interpretation of Section Measurements for Liberation-Practical Aspects

AbstractThe main features of a new reconstruction procedure for particle composition distribution from measurements on sections are presented. The method uses two descriptors: one function for particles and one for ore texture. The solution of the reconstruction problem is obtained by estimating the characteristics of the ore texture function, which, when broken at random into the same particles as those analyzed, gives the measured apparent one-dimensional (1-D) or two-dimensional (2-D) compositions. The application of the method to a sample of iron ore which was separated by heavy liquids shows that the measurements carried out by a QEM*SEM instrument in one (BMA mode) or in two dimensions (PMA mode) reconstruct to the same volumetric distribution as that quantified by physical separation. Examples of applications to multiphase materials, to the assessment of liberation in ball mill grinding of multi phase materials, to the assessment of liberation in ball mill grinding of a copper ore, and to the predi...

Polymers as Advanced Materials

Editorial Essay: The crucial role that polymers play in the electronics industry is just one example of how modern life has been influenced by these multi purpose materials. Development of novel polymers with new and exciting properties and their effective application requires an interdisciplinary effort. This has guided the structuring of the research effort in West Germany. One result of this has been the founding of an Institute for Materials Science in Bayreuth.

Polymers as Advanced Materials

Polymers as Advanced Materials

MODELLING CYCLIC PLASTICITY OF STRUCTURAL STEELS

In this paper we propose a cyclic plasticity model with high accuracy to predict elasto-plastic behaviors of uniaxial steel members subjected to complicated repetitive loads. The model is based on the multi surface plasticity model and material property parameters introduced are a couple of fundamental surface size functions and weighting functions to describe sizes of state surfaces at arbitrary stress-strain phases. It is revealed that the hysteretic model proposed, by which quasi-static fluctuating stressstrain relations can be predicted, is sufficiently accurate from the engineering point of view.

Ａｌ／ＣＦＲＰ多層積層ハイブリッド複合材料の引張特性

Ａｌ／ＣＦＲＰ多層積層ハイブリッド複合材料の引張特性