导　　师： 刘焜

学科专业： 080203

授予学位： 博士

作　　者： ;

机构地区： 合肥工业大学

摘　　要： 颗粒物质在自然界广泛存在,颗粒尺度在1μm～10~4 m范围的物质都可称为颗粒物质,颗粒流润滑是将固体材料以颗粒/(粉末/)状态直接导入摩擦副,使摩擦间隙中处于充满固体颗粒状态,利用颗粒的摩擦、变形、碰撞、挤压和滑滚等微观运动,减少作相对运动两表面的接触,保护表面免于损伤。颗粒流润滑状态下,摩擦间隙中以固体颗粒作为润滑介质,可以实现低摩擦系数、宽温度范围、有冷却、长寿命、可补充等性能特点,是一种新的介质润滑理论与方法,具有较大的理论价值和应用前景。 本文利用端面摩擦试验机和石墨颗粒对颗粒流润滑开展的试验研究证明,颗粒在与摩擦副表面间没有任何附着措施时也可以动态进入摩擦副,但颗粒进入摩擦副的量和均匀性不好控制,且介入性受到颗粒物性、摩擦副设计和工况等的影响。在与粉末冶金铜合金材料、石墨涂层、自润滑复合材料三种润滑方式的对比研究中,发现颗粒流润滑方式可以实现很好的润滑,它的摩擦系数与固体润滑膜、自润滑材料的特性相当。由于颗粒在一定条件下具有流动性,并且可以实现颗粒层的自修复和补偿。颗粒润滑的效果与颗粒本身的性质以及摩擦副的载荷、转速等也有很大关系。同时,基于雾化方案及流化方案构建了相应的试验平台,试验证明石墨颗粒和压缩空气的混合流能进入摩擦副中,实现了良好的减摩作用。 基于离散单元法建立摩擦过程中颗粒物质塑性行为的理论研究模型,对颗粒破坏过程进行了模拟。考察了摩擦副工况/(粗糙度、速度和间隙/)和颗粒强度对颗粒破坏的影响,确定了影响颗粒破坏的因素和相应的参数范围,以期对颗粒的破坏做出准确的预测。 在研制的双筒颗粒流润滑试验装置开展的试验表明,摩擦表面的结构和颗粒介质本身会对颗粒流的摩擦特性产生重 Granular matter is widely existed in nature, and it scales from 1μm to 10~4 m. The granular lubrication means that the solid particles are directly put into the interface of tribopairs and abound in it. By utilizing friction, deformation, collision, crash, slide and rolling of these solid particles, the direct contact of two moving surfaces are minimized, and so the damage of surfaces were avoided. Granular lubrication can be used in key equipments to lubricate their important tribopairs, which can achieve low friction coefficient, wide temperature adaptation, long life and compensable granular lubrication or solid-gas lubrication. This is a kind of lubrication method and well worth further research and development. The tribological characteristics of granular lubrication which uses micro particles have been investigated based on plane contact tribotester. The results show that the continuous supply of particles formed the solid lubrication film. But the amount and the ability of particles entrancing into the clearance are hard to control. The experiments have been carried out to compare the tribological property of surfaces lubricated with copper alloy particles, bonded graphite film and PTFE three layer self lubrication material, the results demonstrate that the friction coefficient, temperature characteristics are similar. Granular lubrication has the properties of longer life and self-replenishment because they can flow in the clearance. The results also show that granular lubrication characteristics are related with particle's physical properties and running state of rubbing surfaces. A devices enables particles and air to mix and flow uniformly and transports to the tribo-pairs are constructed. Through conducting friction and wear on this machine, it testified that particles play an important role on lubrication. A model is established and the break process of the particle is simulated with discrete element method. This model can be used to simulate the plastic behaviors of the particles in clearan

关 键 词： 颗粒流润滑 摩擦系数 离散元 配位数 接触模型 平均接触力

领　　域： [机械工程]