Papers by Keyword: Inclusion

Abstract: Indentation behavior induced by the presence of foreign inclusions in a PVT-grown 4H-SiC wafer is investigated through synchrotron X-ray topography, which revealed the generation of dislocation arrays from the inclusion center along six <11-20> directions. Grazing-incident topographs shows these dislocation arrays exhibit contrast configurations of opposite-signed TED pairs or BPD segments. This correlates with dislocation loops generated due to prismatic punching, and dislocation configuration variation is dependent on the position of prismatic loops with respect to the wafer surface. The stress induced by the inclusion embedded in the 4H-SiC matrix is estimated from the difference in the thermomechanical properties, as the crystal is cooled from the growth temperature.

Abstract: Several defects were analyzed through the manufacturing chain along with their impact on devices. High kill rate of micropipes were seen on both Diodes and MOSFETs as expected. The purity of micropipe detection was found to be affected by the presence of inclusions. Inclusions were successfully sub-classified and separated out from micropipes, based on their location depth from the wafer surface. The effect on devices was found to relate to how deep the inclusion was located, with the ones at the surface having the biggest impact. Various sources of Stacking Faults (SFs) were reported, with Basal Plane Dislocations (BPDs) in the crystal being a major contributor. Higher local densities of BPDs were found to have a more detrimental effect. SFs were sub-classified using the wavelength of each peak. The effect of both overall SFs and each SF sub-type on devices was determined, each sub-type having different effect on the device. Various ways of mitigating the effects of defects and dislocations are demonstrated. Reducing killer defects, SF nucleation probability, and BPDs propagation by epitaxial process optimizations are shown. Resilience up to 3500A/cm² against bipolar degradation is demonstrated by using an engineered buffer layer. Process and device design optimizations show high resiliency against crystal and epi defects and dislocations, with improved yield and lower leakage.

Abstract: Porous ceramic is a heat-resistant porous material with extensive applications, especially for filtering inclusions in aluminum casting industry. To meet local need for these filters, ceramic foam is fabricated by mixing raw materials including kaolin and chamotte as base material, wood sawdust (WSD) as pore-forming agent (PFA), and carboxymethyl cellulose (CMC) with water as binder. WSD content variable: 0%, 5%, 10%, and 15% was used for this research. The mixture was then formed with dry-press method and sintered at 1200°C to form mullite-based local filters. Characterization of samples morphology, composition, and phase were done using SEM-EDS, XRD, and XRF, while its mechanical and thermal properties were characterized by conducting STA, porosity, coefficient thermal expansion (CTE), permanent linear change (PLC), and flexural strength testing. Results showed an increase of WSD addition on the local filter increased the formation number of open-type pores in fiber form on the ceramic microstructure, no significant heat exchanges from decomposition were detected, increased CTE value from 0,0071 to 0,0371%, PLC from 0,0025 to 0,0345%, apparent porosity from 33,29 to 47,95%, and water infiltration from 18,27 to 33,05%, as well as decreased flexural strength from 13,48 to 6,33 MPa and density from 1.82 to 1.43 g/cm³.

Abstract: Low cycle fatigue (LCF) properties of a powder metallurgy(PM) nickel base superalloy FGH720Li were systematically studied in this work, including smooth LCF and notched LCF tested at various temperatures and different stress. The relationship between the fatigue life and applied stress was analyzed both for smooth fatigue and notch fatigue tests. The effects of loading frequency and stress ratio on LCF behavior were also studied. As an important influencing factor of the fatigue life in powder metallurgy superalloy, the effect of inclusions on LCF life was also investigated. The results showed that the fatigue properties of FGH720Li alloy was excellent, when tested at the temperature of 450°C and applied stress of 1230MPa, the fatigue life could exceed 5×10⁴ cycles. When tested at 650°C and 1150MPa, the average fatigue life was still beyond 2×10⁵ cycles.

Abstract: The research of fluid inclusion thin section is to understand the physical and chemical conditions (such as temperature, pressure, density, pH value, composition, etc.) of minerals, rocks and deposits, and to solve the genesis of rocks and deposits; in the process of production, gas inclusions or liquid inclusions should be produced at low temperature, otherwise the inclusions will be destroyed, especially quartz sandstone, weathered rock, mudstone and other minerals Therefore, when the film is made in a humid temperature environment, it is very easy to be deliquesced, especially for the rocks with developed cleavage and many cracks, after rough grinding after polishing, it is easy to produce warping edge, warping angle, bubbles, etc., thus causing the sample piece to deteriorate after polishing; therefore, a large number of pockmarks and cracks will be produced under the microscope. In this paper, starting from the applicable conditions of materials and technological methods, the practical problems of making materials and technological process in rock slice method are introduced in detail. Keywords Inclusion,Manufacturing, Grinding,Polishing,Filming

Abstract: A simple and efficient computational tool modeling the brittle thermal-cracking behavior of a spherical shell encapsulating a round inclusion is presented and compared to existing numerical techniques. Model applications to parametric studies and to particulate composite materials are proposed.

Abstract: The effects of the alloying sequence and refining time on the inclusions in Fe–9Cr alloy reinforced with Y₂O₃ nanoparticles were investigated. The size and number of inclusions in the alloys were determined via optical microscopy, and their morphology and composition were determined via scanning electron microscopy. The Y₂O₃ mainly acted as a nucleating agent in the Si–Mn+Y₂O₃+Ti alloying process, promoting the precipitation of other oxides, which was beneficial for the formation of Y–Ti–O particles. In contrast, no Y–Ti inclusions were formed when the Si–Mn+Ti+Y₂O₃ alloying process was employed. In addition, the inclusions in the alloy tended to stabilize after refinement for 5–10 min. This study offers a general pathway for the manufacture of oxide dispersion strengthened steel via a smelting process.

Abstract: This paper studied the influence of cellulosic flux on the chemical composition, microstructure, formation of inclusions and micro hardness of X42 welded steel. The chemical compositions of the used fluxes are FA: E6010 and FB: E8010-P1, with electrodes has low carbon content. The welding conditions are not constant. The fluxes (FA and FB) have a high content of TiO₂ and SiO₂ and a low Ti and Si content was also detected in the internal (P1) and external (P3) passes. But there was an increase in the Ti content in the fusion zone (P1, P2 and P3) of the different passes gradually, compared to the base metal. The microstructure of the fusion zone (P1, P2 and P3) for each flux is mainly composed of acicular ferrite. The mass concentration variation of Mn is more elevated through the centers of the fusion zone passes (P1, P2 and P3) with the used fluxes. White and black non-metallic inclusions are observed, regardless of used flux. The micro-hardness in fusion zone varies according to the variation of the equivalent carbon in the different electrodes.

Abstract: The present work deals with the analytical resolution of the problem of viscoelastic coated inclusion embedded in a viscoelastic matrix.In a first step, we will study the problem of a linear viscoelastic inclusion, without coating, embedded in a linear viscoelastic matrix.Then, the problem of coated viscoelastic inclusion considering the coating as a thin layer whose viscoelastic properties are different from those of the inclusion and the matrix is performed.The resolution of this problem will be based simultaneously on the Green function technique as well as the interface operator. The analytical expression of the solution is obtained by assuming the isotropy of the matrix as well as the spherical shape of the coatedinclusion.These results are used to determine the effective properties of a heterogeneous medium from a self-consistent approach taking into accountthe interactions between coated inclusions and the equivalent homogeneous medium.

Abstract: The aim of this work is to study the influence of the E6010 and E8018-G fluxes on the chemical composition, microstructure, formation of inclusions and micro hardness in different passes (P1, P2 and P3) of X42 welded steel. The marketed chemical composition of used fluxes is: E6010 and E8018-G, which have a low carbon electrodes. The fusion zone microstructure consists of acicular ferrite. The fluxes (FA and FC) have the high TiO₂ and SiO₂ contents respectively. The high content of Ti and Si, was also detected in the melted zones (P1 ,P2 and P3). The MnO₂ oxide proportion in the fluxes (E6010, and E8018-G) is constant (0.94-0.99). However, the Mn content increases in the melted zones (P3 and P1). The highest percentages of Si and Mn was detected in the outer and inner passes respectively of melted zone, relatively to the base metal. The variation of the elements mass concentrations (Mn, Cr, Si and Ti) shows a contradictory variation on the three points in the melted zone passes (P1 and P3). White and black non-metallic inclusions are observed regardless the used flux. The micro-hardness in the multi-pass melting zone with the fluxes (E6010 and E8018-G) varies according to the variation of the equivalent carbon in the different filler metals.