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Study on Vanadium-nitrogen Powder Fractal Characteristics and Its Application in Cored-wire Production

Author: XieJie
Tutor: ZhangFang;MeiDongSheng
School: Kunming University of Science and Technology
Course: Materials Processing Engineering
Keywords: Cored-wire Vanadium-nitrogen powder Fractal Micro-image Analysis
CLC: TB383.3
Type: Master's thesis
Year: 2009
Downloads: 34
Quote: 0
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Abstract


The quality of vanadium-nitrogen cored-wire which is an essential means of adding alloy element is very important in micro-alloying technology. However, there are always some problems about vanadium-nitrogen cored-wire in Panzhihua iron and steel group, such as uneven axial distribution of solids density and particle size segregation in cored-wire, so the quality of cored-wire batch is often instable. Because of the bad flowability vanadium-nitrogen powder in itself, the powder flow in the funnel is not stable and uneven. It is not easy to improve the quality of the vanadium-nitrogen cored-wire. We should analyses and obtain the characteristics of vanadium-nitrogen powder more accurately and effectively, and ameliorate the existing technological process of the vanadium-nitrogen cored-wire to get more excellent flowability vanadium-nitrogen powder and improve its quality.It has a significant impact on performance and application in engineering to analyses powder physical properties. The production technology and worksite application both affect on powder physical properties. There are many means of powder analysis, and there are lots of differences among them because of their principles and purposes. With the development of fractal theory and microscopy image analysis technique, it is more comprehensive about the powder characteristics analysis. We will apply these techniques in the analysis of vanadium-nitrogen powder in cored-wire. Based on the more comprehensive and representative technological parameters by fractal analysis, it is more effective to guide adjustment and improvement of the exiting technological process.In this paper, it is more accuracy and representative for the next fractal analysis to make a rigorous process of vanadium-nitrogen powder sample preparation, then deduce and verify the fractal characteristics of vanadium-nitrogen powder and gain the particle size distribution fractal dimension and the granule morphology fractal dimension by the fractal theory and the microscopy image analysis. This paper analyses comparatively the difference and connection of the particle size distribution fractal dimension with particle size distribution change of vanadium-nitrogen powder, and the relationship between the particle size distribution fractal dimension and powder flowability. We observe the particle shape and morphology of different particle size by microscopy and detect particle morphology feature parameter, then analyses difference and relationship between the granule morphology fractal dimension and particle morphology feature parameter. According to the fractal characteristics of vanadium-nitrogen powder, we analyses the particle size distribution fractal feature by different breaking means in the existing conditions, improve the used technological process step by step and get more excellent flowability vanadium-nitrogen powder.According to this paper, the results of the analysis show that the vanadium-nitrogen powder is with well fractal characteristics. There is a good linear correlation between the particle size distribution fractal dimension and the powder flowability parameters. The different particle size distribution is with different the particle size distribution fractal dimension. With the particle size distribution increase, the powder particle size distribution fractal dimension is increased gradually; particle size distribution is wider; concentration and inhomogeneity of particle size distribution is less; dispersion of powder is better; powder flowability is improved. There are more than 90% particle witch is massive and fusiform. With the increase of particle size distribution, irregularity of particle shape and morphology is gentle increased, and the particle morphology fractal dimension is decreased significantly. We don’t find good correlation between the particle surface fractal dimension and morphology parameters described but a certain trend correlation, and there is a good correlation between the average surface morphology fractal dimension and the powder flowability parameters. According to the fractal analysis above, the result of particle size distribution structure orthogonal test shows that the better particle size distribution structure is 18:9:11:9:12:26 from 0 to 2800μm. In the existing condition, we analyses the characteristics of the particle size distribution fractal by different crusher and obtain the improved technology process whose particle surface fractal dimension D=2.5388 is closer to optimum. We get a better effect in vanadium-nitrogen cored-wire process and improve the core-wire quality.

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