Towards a plastic engine: Low-temperature tribology of polymers in reciprocating sliding
Towards a plastic engine: Low-temperature tribology of polymers in reciprocating sliding
复制标题
迈向塑料发动机：往复滑动中聚合物的低温摩擦学
作者：
Stead I
对一系列工程聚合物（包括生物衍生的聚对苯二甲酸丙二醇酯 (PTT)）的基础摩擦学研究已在低温（12 C∘ 和− 8 C∘）下进行。该研究的目的是在迪尔曼发动机内用聚合物组合取代传统的磨光铝衬里/聚四氟乙烯 (PTFE) 密封界面。迪尔曼发动机是一种新型活塞发动机，由低温流体（液氮或液态空气）的膨胀驱动，可产生无排放的联合冷却和动力。使用摩擦计来模拟发动机状况。聚合物相对于磨光铝基准的功效是根据预计的材料转移层进行评估的。其大小是通过结合扫描电子显微镜 (SEM)/能量色散 X 射线光谱 (EDS) 和 Abbott-Firestone 曲线（表面纹理的描述）来确定的。引入了摩擦过冲的概念，该概念与 PTFE 样品上测量的磨损严重程度相关。对于发动机而言，低摩擦系数 (CoF) 可减少寄生损失，而低磨损将确保保持活塞密封件的完整性，从而保证发动机的密封能力。除未磨光的聚甲醛 (POM) 和未磨光的铝样品外，在所有样品中均检测到材料转移（通常是从密封件到衬里样品）。这两种组合具有最低的摩擦超调和最低的磨损水平。这些特性也与雅培-费尔斯通曲线的低表面粗糙度和四分位数范围的低梯度有关。这些材料的性能均优于基准密封件/衬里组合，并且 POM 为全聚合物膨胀室提供了潜力。
Fundamental tribological studies of a range of engineering polymers, including a bio-derived Polytrimethylene-terephthalate (PTT) have been conducted at low temperatures (12 C∘ and− 8 C∘). The aim of the study was to replace a conventional honed aluminium liner/polytetrafluoroethylene (PTFE) seal interface with a polymer combination, within a Dearman Engine. The Dearman Engine is a novel piston engine driven by the expansion of a cryogenic fluid, either liquid nitrogen or liquid air, to produce emissions-free combined cooling and power. A tribometer was used to simulate engine conditions. The efficacy of the polymers relative to the honed aluminium benchmark was assessed in terms of a projected material transfer layer. The magnitude of which was determined using a combination of scanning electron microscope (SEM)/energy-dispersive X-ray spectroscopy (EDS) and Abbott—Firestone curves, a descriptor of surface texture. The concept of a frictional overshoot, correlated with the severity of wear measured on the PTFE specimen, is introduced. For the engine, a low coefficient of friction (CoF) leads to reduced parasitic losses and low wear will ensure the integrity of the piston seal is maintained, and so to the sealing capacity of the engine. Material transfer, generally from seal to liner specimens was detected in all but the unhoned polyoxymethylene (POM) and unhoned Aluminium samples. These two combinations had the lowest frictional overshoots and the lowest levels of wear. These are properties that were also linked to a low surface roughness and a low gradient of the interquartile range of the Abbott-Firestone curve. These materials both outperformed the benchmark seal/liner combination and the POM provides the potential for an all polymer expansion chamber.