J V Rajesh, Abimannan Giridharan
School of Mechanical Engineering, Vellore Institute of Technology Chennai, Chennai 600127, Tamil Nadu, India.
Nanomaterials (Basel). 2022 Oct 13;12(20):3587. doi: 10.3390/nano12203587.
The significance of suspending molybdenum di-sulphide powder particles of two distinct mean size viz. Φ40 μm and Φ90 nm into the dielectric of electrical discharge machining is analysed. Crater geometry, surface crack density, skewness, kurtosis and chemical alteration of machined surfaces are considered as outcome measures. A numerical model using finite element analysis is developed to forecast crater geometry. To validate the proposed model, experiments are conducted by varying input parameters such as discharge duration, peak current, and gap voltage. In comparison with the experimental results, the proposed model predicts diameter of crater with an error of 3.34%, 7.32% and 2.76% for discharge duration, peak current and gap voltage respectively for Φ40 μm powder; similarly, 0.19%, 3.65% and 2.78% for Φ90 nm powder. Scanning electron microscope images, 2D roughness profiles and X-ray diffraction profiles are used to assess the partial discharge phenomena, surface crack density, skewness, kurtosis and chemical alteration of the machined surface. For all parameter settings, the Φ90 nm produced surfaces with lessened micro-cracks compared to Φ40 μm. The Φ90 nm creates surfaces with negative skewness and kurtosis less than 3. The deposition of MoS powder particle on the machined surface is revealed through X-ray diffraction analysis.
分析了将两种不同平均尺寸（即Φ40μm和Φ90nm）的二硫化钼粉末颗粒悬浮到放电加工介质中的意义。将加工表面的坑洼几何形状、表面裂纹密度、偏度、峰度和化学变化视为结果指标。开发了一种使用有限元分析的数值模型来预测坑洼几何形状。为了验证所提出的模型，通过改变诸如放电持续时间、峰值电流和间隙电压等输入参数进行实验。与实验结果相比，对于Φ40μm粉末，所提出的模型预测坑洼直径时，放电持续时间、峰值电流和间隙电压的误差分别为3.34%、7.32%和2.76%；类似地，对于Φ90nm粉末，误差分别为0.19%、3.65%和2.78%。使用扫描电子显微镜图像、二维粗糙度轮廓和X射线衍射轮廓来评估加工表面的局部放电现象、表面裂纹密度、偏度、峰度和化学变化。对于所有参数设置，与Φ40μm相比，Φ90nm产生的表面微裂纹较少。Φ90nm产生的表面具有负偏度且峰度小于3。通过X射线衍射分析揭示了MoS粉末颗粒在加工表面上的沉积。
