Papers by Keyword: Surface Defects

Abstract: In this work, an investigation of the mechanically exfoliated MoS₂ under the influence of heat treatment was carried out. Optical and atomic force microscopy techniques were applied to determine the number of layers. Resonant Raman investigation was performed, which clearly showed systematic layer-dependent spectral features. The surface morphology of MoS₂ was investigated with the STM. Atomic-resolution images of MoS₂ is were obtained. Three types of atomic defects were identified as substitutions of donor and acceptor atoms in the Mo atomic layer below the topmost sulfur layer.

Abstract: This paper explores advanced methods and techniques for defect detection, focusing on their effectiveness, challenges, and implications for industrial applications. We explore the combination of CNNs with deflectometry and dark-field polarization imaging for surface defect detection in refrigerator manufacturing and optical components inspection, respectively. We highlight the importance of automated inspection systems in detecting surface defects and discuss the challenges associated with real-time defect detection and limited datasets. This study contributes to advancing defect detection methodologies and provides valuable insights for industrial quality control processes.

Abstract: In recent years, surface defect detection methods based on deep learning have been widely applied to steel plate surface defect detection. By locating and classifying defects on the surface of steel plates, production efficiency can be improved. However, there is still a conflict between speed and accuracy in the defect detection process. To address this issue, we propose a high-precision, low-latency surface defect detection algorithm called the GhostConv-ECA-YOLOv5 Network (GEA-Net). The GEA-Net model can predict defect categories without compromising classification and detection accuracy. Experimental results show that our proposed improved model has higher performance compared to other comparative models, achieving a 75.6% mAP on the NEU-DET dataset.

Abstract: Abstract The use of replication kits has recently become an integral part of the field of non-destructive testing (NDT). Classical surface NDT methods are thus advantageously supplemented by surface prints in selected places of the inspected material. Replicate kits are set to be the fingerprint surface structure requiring no special surface preparation prior to collection of replicas and are intended for the 3D measurement of the dimensions of surface defects. Replicas are then evaluated using a 3D optical profilometer with optical or laser-optical lenses.

Abstract: This article deals with the problematics of the production of small castings using gravitational investment casting. These are castings with a relatively complex shape, which are used as parts of trigger assembly for musical wind instruments. During their production, various defects occur which are connected with the casting process. The aim of this article is to describe the defects and suggest possible methods for removing them. The first step was to find and identify these defects using metallographic and EDX microanalysis. Furthermore, a simulation calculation of the casting process was used to determine the influence of the casting geometry on casting quality. Based on these analyses, the most suitable alloy and casting system geometry were proposed for the production of the casting.

Abstract: The surface structure of the WSe₂ were studied using scanning tunneling microscopy. Exfoliation method in an ultra-high-vacuum chamber method is used to obtain a clean surface of WSe₂ samples with atomically smooth terraces and multi-layer steps. Atomic-resolution images revealed two types of atomic defects of surface or near surface. These defects have been identified as the defects in the tungsten atom layer just below the topmost selenium layer.

Abstract: Modern continuous mills FQM are high-performance technological units that allow you to get products of a wide range. The paper presents the results of the study of the effect of the time of holding the mandrel in the extreme position of the continuous mill FQM (Fine Quality Mill) on the probability of defect formation of surface defects. The problems of сcomputational simulation of the process of continuous rolling of pipes were set and solved. It is established that the increase in the holding time of the mandrel allows to reduce the sliding of the metal on the surface of the tool, and contributes to a stable process of removing the mandrel without the formation of defects on the inner surface of the draft pipe. The results of solving the problems of сcomputational modeling allowed to formulate technical recommendations aimed at reducing the probability of surface defects in the production of pipes at the FQM mill.

Abstract: This paper deals with rarely occurring defect on the surface of the tinplates produced in the conditions of U. S. Steel Košice, s.r.o. at the cleaning section of the continuous annealing line (CAL), which was caused by burnt. Random occurrence of such surface imperfections was observed within the short period of time (two months) for various continuous annealed tinplate grades, i.e. TH415, TH435 or TH550 with the thickness of the materials in the interval of 0.172 – 0.240 mm. Surface defects caused by burnt (thermal attack) manifested in different ways. Their appearance on the sheet surface was spot with regular or irregular circle shape, as well as line with the length of up to 2 mm oriented not directly in the rolling direction. By observing of the imperfections in scanning electron microscope (SEM) it was found that the surface of the steel substrate was always compact in the defective areas with clearly visible rolling lines. Foreign material, EDS analysis of which revealed that its chemical composition was on the basis of Fe and Cr, was deposited on the surface of the base material. The appearance of the foreign material shape indicated that it was in the liquid state at the time of incidence on the steel substrate surface. Metallographic analysis from the longitudinal metallographic sections through the defective areas revealed that the substrate under the spot defect with regular circle shape had thermally influenced microstructure. Similar manifestations of the microstructure influence were observed for the line defects. In the case of the spot defect with irregular shape, the microstructure of the material was not influenced, what indicated that the particle of liquid metal was solidified at the time of incidence on the plate surface. After revising technical conditions of the cleaning section of CAL, this type of imperfection was suppressed.

Abstract: Epitaxial growth of 4H-SiC on 150 mm wafers with the recombination-enhancing buffer layer was studied. In order to accomplish the reduction of basal plane dislocations in the buffer layer to almost free level and assure its quality in production, non-destructive evaluation using photoluminescence method was investigated. Epitaxial wafers of which the buffer layer and the drift layer have more than 99% BPD free area in a 2.6 mm × 2.6 mm block evaluation were realized by optimizing the epitaxial growth conditions. Furthermore, very low surface defects density and excellent thickness and doping uniformity were achieved simultaneously.

Abstract: A metallurgical examination of surface defects of pipes made of steel of strength category X70 was carried out. The characteristic microstructural features of defects were determined. The causes of the formation of surface defects of the pipe were established. Comparison of the actual and calculated compositions of the detected satellite inclusions was conducted.