Ormanova Maria, Stoyanov Borislav, Nedyalkov Nikolay, Valkov Stefan
Academician Emil Djakov Institute of Electronics-Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee Blvd, 1784 Sofia, Bulgaria.
Department of Industrial Desing and Textile Engineering, Technical University of Gabrovo, 4 H. Dimitar Srt, 5300 Gabrovo, Bulgaria.
Materials (Basel). 2023 Jul 26;16(15):5237. doi: 10.3390/ma16155237.
This paper aims to investigate the impact of beam deflection geometry on the structure, surface architecture, and friction coefficient of electron-beam-modified TC4 titanium alloys. During the experiments, the electron beam was deflected in the form of different scanning geometries, namely linear, circular, and matrix. The structure of the treated specimens was investigated in terms of their phase composition by employing X-ray diffraction experiments. The microstructure was studied by scanning electron microscopy (SEM). The surface architecture was examined by atomic force microscopy (AFM). The friction coefficient was studied by a mechanical wear test. It was found that the linear and circular deflection geometries lead to a transformation of the phase composition, from double-phase α + β to α' martensitic structure. The application of a linear manner of scanning leads to a residual amount of beta phase. The use of a matrix does not tend to structural changes on the surface of the TC4 alloy. In the case of linear geometry, the thickness of the modified zone is more than 800 μm while, in the case of EBSM using circular scanning, the thickness is about 160 μm. The electron-beam surface modification leads to a decrease in the surface roughness to about 27 nm in EBSM with linear deflection geometry and 31 nm in circular deflection geometry, compared to that of the pure TC4 substrate (about 160 nm). The electron-beam surface modification of the TC4 alloy leads to a decrease in the coefficient of friction (COF), with the lowest COF values obtained in the case of linear deflection geometry (0.32). The results obtained in this study show that beam deflection geometry has a significant effect on the surface roughness and friction coefficient of the treated surfaces. It was found that the application of a linear manner of scanning leads to the formation of a surface with the lowest roughness and friction coefficient.
本文旨在研究电子束偏转几何形状对电子束改性TC4钛合金的结构、表面形貌和摩擦系数的影响。在实验过程中，电子束以不同的扫描几何形状进行偏转，即线性、圆形和矩阵形。通过X射线衍射实验研究了处理后试样的相组成结构。通过扫描电子显微镜（SEM）研究了微观结构。通过原子力显微镜（AFM）检查了表面形貌。通过机械磨损试验研究了摩擦系数。结果发现，线性和圆形偏转几何形状导致相组成从双相α+β转变为α'马氏体结构。采用线性扫描方式会导致β相有残留量。采用矩阵形扫描不会使TC4合金表面产生结构变化。在采用线性几何形状的情况下，改性区厚度超过800μm，而在采用圆形扫描的电子束选区熔化（EBSM）情况下，厚度约为160μm。与纯TC4基体（约160nm）相比，电子束表面改性使采用线性偏转几何形状的EBSM中表面粗糙度降低至约27nm，采用圆形偏转几何形状的降低至31nm。TC4合金的电子束表面改性导致摩擦系数（COF）降低，在采用线性偏转几何形状的情况下获得的COF值最低（0.32）。本研究获得的结果表明，电子束偏转几何形状对处理后表面的粗糙度和摩擦系数有显著影响。结果发现，采用线性扫描方式会形成粗糙度和摩擦系数最低的表面。
