Papers by Keyword: Replica

Abstract: The aim of the study was to validate non-destructive diagnostics of surface of tools and metal sheets after steel grit blasting. We used replicas produced by fy Struers, known under commercial name RepliSet-F5. The replicas were extracted from surfaces of thirty specimens with PVD coatings (CrN, TiCN) and from flat specimens after steel grit blasting. Qualitative and quantitative parameters characteristic of surface morphology were determined by means of an optical profilometer, and confocal microscope was used for surface contactless metrology measurements. We observed a qualitative coincidence of morphological images of original surfaces and replicas. The values of the quantitative parameter Sa (Arithmetic mean height according to ISO 25178) of surfaces and replicas extracted from them differed at the second decimal place. Replicas document well the surface morphology and allow one to obtain information about the state of surface in difficult-to-access sites of the tools or constructions.

Abstract: In the context of green economy supported and widespread by United Nations (UN), the renewable energy sources are the unique mechanism to universalize the access to energy. Face to this strategic direction of change is essential to develop efficient components for saving energy such as porous ceramics that associate light with mechanical strength. Thus, the objective of this work concerns to improve the homogeneity of porous size distribution of yttria porous ceramics by evaluating their morphology during replica processing. Samples were subject to immersion into 30vol% yttria aqueous suspensions during an interval from 1min to 120min and sintered through careful thermal conditions. Based on the results, the weight and morphology of porous structure samples were directly influenced by immersion time, whereby intervals from 30-120min showed the best final products.

Abstract: Data replication is adopted to improve data access performance in cloud computing environment. When different sites hold the same data resource, there are significant benefits while selecting the best one. In this paper, we propose a new replica selection algorithm based on prediction. Analyzing the factors infecting replica selection, The grey system theory is utilized to help predicting the data response time on the basis the GM(1,1) grey dynamic model; Meanwhile the Markov chain is applied to achieve state transition probability matrix to predict the reliability of replicas in the form of probability by the system state classification. The simulation results show that in our replica selection model, the prediction is valid, helpful to selection decision, and is able to achieve load balance between nodes holding replicas.

Abstract: Data replication is adopted to improve data access performance in cloud computing environment. When different sites hold replicas, there are significant benefits while selecting the best replica. In this paper, we propose a new replica selection algorithm based on prediction. Analyzing the factors infecting replica selection, The grey system theory is utilized to help predicting the data response time on the basis the GM(1,1) grey dynamic model; Meanwhile the Markov chain is applied to achieve state transition probability matrix to predict the reliability of replicas in the form of probability by the system state classification. The simulation results show that in our replica selection model, the prediction is valid, helpful to selection decision, and is able to achieve load balance between nodes holding replicas.

Abstract: This paper discusses reasons for using replicas of fracture surfaces of ceramics, describes several replicating methods and materials, and presents examples that compare replicas with actual fracture surfaces. Advantages of using replicas include being able (1) to examine large pieces without having to cut them down to size, (2) to provide convenient archiving of fracture surfaces, and (3) to eliminate sub-surface scattering of light. Many times, replicas provide clearer views of untreated (uncoated) fracture surfaces than can be obtained by direct observation. Replication using cellulose acetate tape and two types of silicone rubber (filled and unfilled) are described. Both methods are fast, relatively inexpensive, and non-destructive. Images of replicas of fracture surfaces of a glass and several ceramic materials (including electrical porcelain and several polycrystalline ceramics) are compared with images of actual fracture surfaces.

Abstract: This paper shows the result of some metallographical examinations that have been carried out on low-alloyed Cr-Mo-V heat resistant steel. The aim of this research is to present and compare the advantages and disadvantages of the mainly applied metallographical methods. These techniques are optical microscopy, scanning electron microscopy, replica method and special applications of these methods. We have proved that using the investigated methods together gives much more information about the lifetime of the specimen than using these techniques particularly.

Abstract: Ceramic foams can be used as filters, dust collectors, light weight components and catalyst carriers. They can be produced by a variety of techniques. The performance of ceramic foams will be strongly improved when their mechanical properties are improved. For this reason, we produced ceramic foams both by a modified reaction bonded (RB) replica technique and by gel casting. With both methods, reticulated foam structures with enhanced mechanical strength were obtained. Zeolites are a special type of materials that are characterized by high catalytic properties. They can be brought on a structured carrier by dip and slurry coating. Nevertheless, in situ coating has as main advantage that the support is used as the base for nucleation. This results in the formation of a chemical bond between the zeolite crystals and the support. The goal of this contribution is twofold: at first we demonstrate how Al2O3 foams with improved mechanical strength can be produced both by the modified RB-alumina replica technique and by gel casting. Secondly, it is shown that these ceramic foams can be coated with (silicalite) zeolite crystals by insitu crystallization from a precursor sol. The two-layer material combinations have been characterized with FESEM, XRD, CT (computer assisted tomography), IA (Image Analysis) and by mechanical tests.

Abstract: Templating methods provide an alternative approach for fabricating macroporous solids with three-dimensionally ordered arrays of pores with diameters from tens to hundreds of nanometers. The main goal of this work is the fabrication of thermoelectric-opal composite and inverse opals made of thermoelectric material in order to obtain enhanced performance by reducing the thermal conduction. Chemical bath deposition (CBD) has been employed and thermodynamic modelling was used to obtain optimum conditions for the desired phase of particle formation within the channels of the opal-like structures. The wetting behaviours of opals were considered in the choiceof the appropriate solvents. When loading is finished, the precursor is decomposed and reduced when appropriate. The opal template is then removed by pyrolysis to obtain the macroporous structures. The structural properties of materials produced were investigated.