Papers by Keyword: Transition Layer

Abstract: A model of the transition layer between the shell and the core of a ceramic matrix composite from coal waste and clay has been developed. The chemical, granulometric and mineral compositions of the beneficiation of carbonaceous mudstones and clay were studied. The technological and ceramic properties of raw materials for the samples manufacturing were determined. The method of manufacturing multilayer ceramic samples from coal waste, clay and their mixture is given. The number of transition layers in the contact zone between the clay shell and the core from coal wastes is determined. The deformation and swelling phenomena of model samples from coal wastes, clay, and their mixtures were revealed at the firing temperature of more than 1000 °C. The formation of a reducing ambient in the center of the sample with insufficient air flow is shown. The influence of the carbonaceous particles amount and the ferrous form iron oxide in the coal wastes on the processes of expansion of multilayer samples during firing has been established.

Abstract: We present three different ways of transferring 3C-SiC layers grown on silicon on top of a SiC carrier using a carbon glue layer. Our main focus was upon the growth on the transition layer, as 3C-SiC does not feature any polarities in the <100> or <-100> direction. We realized a stable and reproducible process by following a wet chemical approach, dealing with the difficulties of handling thin but freestanding 3C-SiC layers. By using this way, we transferred approximately 130 μm thick pieces using their horizontal hot-wall reactor (M10), which were chemo mechanically polished and afterwards fixed on our SiC carriers. Implementing such a seeding stack into our growth setup, we managed to grow between 20 μm and 130 μm thick layers on top. We have proven the possibility to grow on the transition layer. Furthermore, we observed a slight reduction in protrusion density, which is currently one of the main defects in such layers.

Abstract: One kind of Al₂O₃ ceramic-lined steel pipe was prepared with the gravitational separation SHS method by using the reaction system of Al-Fe₂O₃-Cr₂O₃. The element line scans of transition structure and the element plane scans of ceramic coating far away from transition layer were analyzed by Scanning Electron Microscopy and Energy Dispersive Spectroscopy, and then they were used to discuss the coating structure and interface bonding mechanism, and investigate the element composition distribution of coating. All of these were closely related to improving the properties of ceramic-lined steel pipe. The results showed that a transition layer was formed between metal pipe and ceramic coating, it was due to the gravitational separation and molecular diffusion motion of the reaction products in molten state; in the transition structure the amount of the reaction elements was gradually transitional from the direction of the coating-transition layer-steel pipe, which could reduce the stress difference between the layers; in the coating far away from the transition layer, only small amount of Fe embedded in the ceramic was left in the form of Fe-Cr alloy, while Cr was uniformly enriched in the Al₂O₃ ceramic, these all have great influence on the anti-corrosion ability of coating.

Abstract: The results of experiments aimed at obtaining multi-component coatings, having a wider range of properties compared to single-component coatings, are provided. The process of formation of coating based on multi-component alloy Co (18...20%)-Cr (5...7%)-Al (0.3...0.4%)-Y(0.2...0.5) was studied. The chemical composition and thickness of the coating as well as the state of the transition layer were also studied. The results of electron probing and X-ray fluorescence microanalysis of obtained coatings are provided. This paper also demonstrates that the properties of surface microrelief are determined by the conditions of coating formation; that each sample of coating has similar sets of chemical elements, that their concentration depends on the precipitation conditions, chemical elements are equally distributed along the thickness of samples, and the diffusion zone of coating materials and substrate is almost non-existent. The low content of substrate material was found in obtained coatings. As the coating thickness increased, the content of substrate material decreased sharply.

Abstract: The paper seeks to analyze the necessity of setting functional layer between base and surface course of cement concrete pavement. Based on laboratory test, test device is developed to test accumulated deformation of the functional layer mixture. Use common mixture AC-16, AC-13, and AC-10 to analyze the increasing law of cumulative deformation of mixture. According to the results, 3.5mm is set as the maximum limits of accumulated deformation for function layer under specified test condition in this article, which provides theoretical reference for the pavement layer design of cement concretes.

Abstract: In this paper, the effects of Cr content and impact load on the microstructure and properties of High Manganese Steel (HMS) were investigated. The results show that the hardness of HMS was increasing when the Cr content increased, but the hardness was not much changing when the Cr contents changed from 2% to 2,5% of weight. Under the impact load, the microstructure and the hardness were changed also. The Cr content effected on the depth of transition layer on surface under the impact load and the twinning occurred during impacting load.

Abstract: Abstract: In order to study the weak point and influence factor on creep rupture properties of dissimilar joint, a simulation joint which contains a transition layer has been built with the same welding parameters, the same base and weld materials as the real structure, providing theoretical principle for weld material selection and welding process optimization. In the creep rupture test of the simulation joint, most fractures are found at the fusion zone of transition layer. The existence of a softened layer at fusion zone of transition layer has been proved with metallographic observation, micro hardness test, chemical composition analysis and scanning electron microscope (SEM). The softened layer causes strain concentration and makes it much easier to fracture. A great Cr gradient between transition layers is considered as the reason of soften layer formation, since it leads carbon distribution and decreases the hardness where lack C element. In addition, some features of crystallization direction of fusion zone in transition layer have been found, which could be harmful on creep rupture properties too.

Abstract: The copper alloy/30CrMnSi steel bi-metal composite materials were prepared by the interface diffusion bonding method. The diffusion of elements close to the bonding interface was studied and the formation and growth mechanism of dissolution layer were discussed as well. The results showed that a diffusion transition layer could be formed with the different widths for copper alloy/30CrMnSi steel integrated material. A diffusion transition layer was formed close to 30CrMnSi steel side due to the inter-diffusion of the alloy elements. The microstructure characterization showed that no harmful brittle phase presented around the interface, and two heterogeneous materials had a good metallurgical bonding.

Abstract: The coating was made of base coating (NiCrAlY) and superficial coating (ZrO2 + Y2O3) by plasma spray. The microstructure and phase structure of the coating were investigated by using the scanning electron microscope and the X-ray diffraction. The oxidation process can be divided into three stages: The main oxidation products is θ-Al2O3 but not continuous α-Al2O3 film in oxidation prophase; Continuous α-Al2O3 film generated quickly with the transition of θ-Al2O3 to α-Al2O3 in the oxidation reaction. The oxidation reaction becomes complicated when the content of Al decrease and Ni is also oxidized to NiO. Oxidation kinetics curves of 1200°C is basically accord with parabolic law.

Abstract: Based on a seven-storey Masonry structure building with bottom framework . This paper states and analysis it’s aseismic design,has been obtain the internal forces and deformation of this structure in the earthquake. Mathematical model built in full accordance with the current design specifications ,The comparison of calculated results with experimental results agree with well . In addition present a sustainable design method to improve the seismic capacity of such structures in earthquake action.Have a certain reference value to the engineering staff.