聚醚醚酮及其复合材料的摩擦学研究进展

评述了聚醚醚酮（PEEK）及其复合材料的摩擦磨损性能，在滑动过程中形成的摩擦转移膜以及磨屑的研究，总结了聚合物基复合材料摩擦学研究的一般方法及规律，介绍了关于用PEEK复合材料制造的轴承，齿轮等进行的摩擦学研究，以及等离子体表面处理和颗粒增强对PEEK及其复合材料摩擦学性能的影响。     

Study on Tribological Properties of Polytetrafluoroethylene Drawn Uniaxially at Different Temperature

Summary: Wear behavior correlations with morphology have been established from polytetrafluoroethylene (PTFE) drawn at 200, 327, and 375 °C with draw ratio about 4. The friction coefficient and wear rate for PTFE drawn at 327 °C are lower and the wear rate is lower than that of undrawn PTFE by about 30%. The structures of samples were characterized by scanning electron microscope (SEM), DSC, and wide angle X‐ray diffraction (WAXD). Results indicate that the debris morphologies of samples are different. The differences in the tribological behavior of undrawn and drawn samples were attributed to the improvement of the degree of the crystalline, fibrillation, and orderliness by drawing, especially, for PTFE drawn at 327 °C. The orderliness of molecular arrangement along the drawn direction is also higher for PTFE drawn at 327 °C than those of PTFE drawn at 200 and 375 °C, respectively. Therefore, the intensity of covalent bond along drawn direction is higher. The shear resistance and the deformability of the material are greatly improved and the size of the wear breakage unit decreases, which results in a good tribological property for PTFE drawn at 327 °C.

SEM morphology of fractured surface perpendicular to the draw direction for PTFE drawn at 327 °C.     

铝质基体上Ti(C,N)/TiN多元多层膜工艺参数研究

首先在大范围内调节负偏压和基体温度两个参数，实现在铝质材料基体上沉积与基体结合良好的TiN膜，在此基础上通过调节N2、C2H2工作气氛流量比及Ti(C，N)、TiN膜层的层数，沉积了3类不同的膜，并对其力学与摩擦学性能进行了考察。结果表明：在(N2 C2H2)总流量一定的情况下，C2H2流量增大，则使Ti(C，N)膜层中含C量增多，膜层硬度提高，但韧性变差，表面变粗糙；在总厚基本不变的情况下，层数增多，单层变薄，使膜材晶粒细化，硬度提高，韧性变好。在3类膜中，1#膜C2H2流量适当且膜层数最多(6层)，其摩擦学性能表现最好，临界荷载为76N，显徼硬度为1911HV0.1，与基体相比，耐磨性提高了10倍多。     

Alternative tribological coatings to electrodeposited hard chromium: a critical review

ABSTRACT

The traditional importance of hard chromium electroplating in surface engineering is recognised and the key features of this well-established technology are summarised. Despite the high hardness, corrosion protection and wear resistance of chromium electrodeposits, a number of alternative coating compositions and application techniques have been developed for specific applications in tribology. Environmental challenges associated with hard chromium electroplating are highlighted and the need to develop and evaluate alternative coatings is stressed. Key examples of the alternative coatings are described, including their method of application, microstructure and tribological performance in controlled service environments. Research needs requiring rapid development are highlighted. A summary is given of the most competitive coatings and those having the potential to match the performance of hard chromium in selected applications are identified.     

石墨表面金属化对铜基复合材料摩擦学性能的影响

利用化学镀技术制备镀铜和镀镍石墨粉,采用粉末冶金复压复烧工艺制备铜基石墨自润滑复合材料,测试了复合材料的摩擦磨损性能,利用X射线衍射、扫描电镜和能谱仪等分析该复合材料的结构、摩擦磨损性能及机理。结果表明：石墨表面铜、镍镀层改善了石墨和铜合金基体界面结合,摩擦过程中所形成的润滑膜与基体粘附性好,显示出更好的润滑减摩效果,摩擦副摩擦因数由0.24降低到0.20,磨损率降低约50%;实验条件下,6%（质量分数）石墨铜基复合材料经历轻微磨损、中等磨损和严重磨损3个磨损过程;而6%镀铜、镀镍石墨铜基复合材料只经历轻微磨损和中等磨损两个磨损过程。     

塑性加工摩擦学研究的新方法——三维表面形貌分析

确定金属表面的粗糙度和结构是塑性加工摩擦学研究中的重要内容,但以往使用接触式粗糙度促进行测量的方法有很大局限性,目前国外已采用三维表面分析的方法进行测量和研究,本文介绍了三维表面分析原理、设备、主要特征参数、对表面的分析实例及其特点,使读者对这一新技术有一全面的了解。     

Pulse current co-deposition of Ni-WS2 nano-composite film for solid lubrication

This study was undertaken to observe the effect of nano-composite coating on steel surface for enhancing its tribological properties. In the investigation, EN31 steel surfaces were coated with nano-composite (Ni-WS₂) by pulse current co-deposition process in order to improve the tribological properties of the surface. The coatings were prepared according to different parameter settings. The effect of variations on coating thickness, microstructure, surface morphology, microhardness and tribological properties was observed. The maximum coating thickness of 117?µm with 8% by weight of WS₂ particle concentration could be attained with the following parameter settings: applied voltage: 5?V; pulse frequency: 20?Hz; WS₂ concentration: 20?g/l; duty factor: 0.6 and bath temperature: 50°C. The average friction coefficient of the deposited surface was 0.11, which is significantly less than that of the EN31 steel surface (average coefficient of friction >?0.5).     

Improvement of lubrication and cooling in grinding

The presence of air boundary layer around a grinding wheel impedes the proper entry of cutting fluid into grinding zone and thereby lubrication and cooling are hampered. It leads to the thermal damage to the workpiece and rapid wheel wear. This experimental work is aimed at increasing the lubrication and cooling effects in grinding by a novel method of using scraper board. The experiments are conducted, using the scraper board, to find the critical region where the air pressure is zero. The coolant jet has then impinged into the grinding zone which is maintained within the critical region. The requirement of specific energy, surface texture, and mechanical properties of the ground surface are analyzed and compared with the traditional grinding and the grinding at various positions of scraper board. Results show that the grinding ratio improved by 35.6and 119%, surface roughness decreased by 36 and 54.2%, while the requirement of specific energy is reduced by 50.8 and 57.3% when scraper board is positioned at the critical distance in comparison to the 57.5° position and no scraper board, respectively. The results indicate that the introduction of fluid in the present method can improve the process efficiency and the product quality effectively.     

一种大行程高精度微执行器的研究

为了解决宏/微驱动系统中大行程和高精度之间的矛盾,研制了一种基于摩擦工作原理的压电陶瓷驱动的新型大行程、高分辨率步进式微执行器,该微执行器的行程为300mm、位移分辨率为0.02μm.提出了一种新型的基于压电陶瓷的柔性四杆型可调预压装置,并进行有限元分析.建立了微执行器系统的动力学模型,基于Karnopp“粘滞-滑移“摩擦模型分析微执行器力学特性.对微执行器的运动特性进行实验测试.     

化学复合镀Ni-W-P合金镀层的摩擦学性能研究

通过滑动磨损试验，使用显微硬度计、差热分析仪、SEM和X—ray衍射仪等仪器，研究Ni—W—P合金镀层的磨损特性及磨损机制．结果表明，Ni—W—P合金镀层经400℃时效显微硬度达到Hv1325，磨损率为6．4mg／h．cm．在边界润滑条件下，镀层的磨损机制为粘着磨损与磨粒磨损并存。