Vidyut Dey

OPTIMIZATION AND SURFACE MODIFICATION OF Al-6351 ALLOY USING SiC–Cu GREEN COMPACT ELECTRODE BY ELECTRO DISCHARGE COATING PROCESS

This paper introduces the surface modification of Al-6351 alloy by green compact SiC–Cu electrode using electro-discharge coating (EDC) process. A Taguchi L-16 orthogonal array is employed to investigate the process by varying tool parameters like composition and compaction load and electro-discharge machining (EDM) parameters like pulse-on time and peak current. Material deposition rate (MDR), tool wear rate (TWR) and surface roughness (SR) are measured on the coated specimens. An optimum condition is achieved by formulating overall evaluation criteria (OEC), which combines multi-objective task into a single index. The signal-to-noise (S/N) ratio, and the analysis of variance (ANOVA) is employed to investigate the effect of relevant process parameters. A confirmation test is conducted based on optimal process parameters and experimental results are provided to illustrate the effectiveness of this approach. The modified surface is characterized by optical microscope and X-ray diffraction (XRD) analysis. XRD analysis of the deposited layer confirmed the transfer of tool materials to the work surface and formation of inter-metallic phases. The micro-hardness of the resulting composite layer is also measured which is 1.5–3 times more than work material’s one and highest layer thickness (LT) of 83.644μm has been successfully achieved.

A Study to Increase Weld Penetration in P91 Steel During TIG Welding by using Activating Fluxes

Activated Flux TIG (ATIG) welding is a unique joining process, invented at Paton Institute of electric welding in 1960. ATIG welding process is also known as flux zoned TIG (FZTIG). In this process, a thin layer of activating flux is applied along the line on the surface of the material where the welding is to be carries out. The ATIG process aids to increase the weld penetration in thick materials. Activating fluxes used in the literature show the use of oxides like TiO2, SiO2, Cr2O3, ZnO, CaO, Fe2O3, and MnO2 during welding of steels. In the present study, ATIG was carried out on P-91 steel. Though, Tungsten Inert Gas welding gives excellent quality welds, but the penetration obtained in such welding is still demanding. P91 steel which is ferritic steel is used in high temperature applications. As this steel is, generally, used in thick sections, fabrication of such structures with TIG welding is limited, due to its low depth of penetration. To increase the depth of penetration in P91while welding with ATIG, the role of various oxides were investigated. Apart from the oxides mentioned above, in the present study the role of B2O3, V2O5 and MgO, during ATIG welding of P91 was investigated. It was seen that, compared to TIG welding, there was phenomenal increase in weld penetration during ATIG welding. Amongst all the oxides used in this study, maximum penetration was achieved in case of B2O3. The measurements of weld penetration, bead width and heat affected zone of the weldings were carried out using an image analysis technique.

THE PHENOMENON OF SURFACE MODIFICATION BY ELECTRO-DISCHARGE COATING PROCESS: A REVIEW

Electro-discharge machining (EDM) process is one of the most successful non-conventional machining processes for the last three to four decades in machining very hard materials which are tough to machine by conventional machining process. In the EDM process, besides the erosion of workpiece material, the inherent nature of the process leads to some tool material removal also. This nature of EDM process has been exploited by the researchers which led to the invention of Electro-discharge coating (EDC). EDC is a surface modification technique where tool material gets deposited on the substrate surface due to the sparking effect. It works on reverse polarity to that of EDM. A literature review based on the phenomenon of surface improvement by EDC process and also the future drifts of its application are shown in this paper.

A Three-Layer Approach for Overlay Text Extraction in Video Stream

Overlaid texts are annotated text on video frames embedded externally for providing additional information to viewer of video sequences. The externally embedded texts can be used for auto-indexing and searching of video files in a video library using contextual contents inside video files. In this paper, we proposed a novel algorithm to detect and extract the overlaid text in digital video which allows users to get a much deeper understanding of video content. The proposed algorithm uses SVM as machine learning approach to filter/extract text more accurately. It uses multi-resolution processing algorithm due to which the proposed algorithm is able to extract embedded text of different font size from same video frame. Text detection from video sequences enables us to auto-indexing of video based on text embedded on video frames. Embedded texts enable deaf and hard-of-hearing users to watch videos. It is also useful for the people, who have hearing impairments from understanding the content of video. It also helps to those kinds of people who want to watch video in sound-sensitive environments.