Si_3N_4陶瓷旋转超声磨削加工的表面摩擦特性

为了探索结构陶瓷材料在摩擦过程中表面形貌的变化规律及其对摩擦特性影响,分析了摩擦过程中材料的接触过程及力学关系,并对旋转超声磨削加工的Si3N4陶瓷试样开展了摩擦表面形貌、摩擦因数等特性的试验研究。首先根据接触特点和材料特性,基于分形理论推导出接触面总载荷计算公式,基于该公式建立了结构陶瓷摩擦因数分形模型。分析结果表明:当初始表面轮廓分形维数分别为1.4,1.45,1.5和1.55时,摩擦因数与摩擦后表面轮廓分形维数呈类似正态分布曲线。然后通过旋转超声磨削加工的Si3N4陶瓷试样面面接触摩擦试验,研究了摩擦后陶瓷材料表面微观形貌和摩擦因数变化规律,分析了各因素对摩擦因数的影响。试验结果表明:产生微观裂纹是Si3N4陶瓷摩擦后表面微观形貌的显著特点;温度值等于160℃是Si3N4陶瓷摩擦因数由下降转为上升的拐点;当施加载荷为360N和往复频率为80Hz时,摩擦因数最大。得到的结果为通过表面形貌控制提高结构陶瓷耐磨性能提供了技术支撑。

Surface friction characteristics of Si3N4 ceramics machined by rotary ultrasonic grinding

For investigating on the surface morphology variation of structure ceramic materials and its effect on the friction characteristics during friction, the relationships between contact and mechanical were analyzed in friction process. Meanwhile, the friction characteristics of Si₃N₄ ceramic samples machined by rotary ultrasonic grinding, such as friction surface morphology and friction coefficient were studied with experiments. First, according to the contact characteristics and material properties, the calculation formula of the total load was deduced based on fractal theory. The friction coefficient fractal model was also established on the basis of above. The analysis results shows that the relationship between friction coefficient and surface profile fractal dimension after friction is similar to the normal distribution curve, when the initial surface profile fractal dimension is 1.4, 1.45, 1.5 and 1.55 respectively. Then with surface to surface contact friction experiments of Si₃N₄ ceramic sample machined by rotary ultrasonic grinding, surface topography and friction coefficient variation after friction were investigated. And the influence factors on the friction coefficient were also analyzed. The results indicate that micro-cracks are the notable feature of the surface morphology for Si₃N₄ ceramic friction. The temperature of 160℃ is the inflection points of fall and rise for Si₃N₄ ceramic friction coefficient. The friction coefficient is the maximum when the applied load is 360 N and reciprocating frequency is 80 Hz. It concludes that the machining surface morphology control improves the wear resistance of structure ceramics.