氧化硅陶瓷高温摩擦学性能

本文研究热压氮化硅陶瓷与３Ｃｒ２Ｗ８Ｖ钢组成的销－盘摩擦副，在空气中非润滑条件下，４００￣８００℃不同载荷（４９￣３４３Ｎ）的摩擦磨损性能；测定了磨擦系数的Ｓｉ３Ｎ４销的磨损因子；通过对Ｓｉ３Ｎ４磨损面的ＳＥＭ形貌观察、Ｘ射线相结构分析，探讨了陶瓷销的磨损机理。     

干摩擦条件下Ti（CN）—Al2O3复合陶瓷与金属摩擦副的摩擦学特性研究

为了模拟陶瓷刀具的磨损过程，对干摩擦条件下Ｔｉ（ＣＮ）－Ａｌ２Ｏ３复合陶瓷与纯铝、纯铁和不锈钢３种金属的摩擦、磨损特性进行了研究。结果表明：随着速度或载荷的增加，摩擦副中金属与陶瓷的磨损量均很快增大。金属的磨损量比对摩的陶瓷的磨损量大得多。３种金属中，铝的磨损量最大，铁和不锈钢的磨损量较小。与铝与摩的陶瓷的磨损量小是由于：（１）铝的硬度小，易剪切，不会对陶瓷造成较大损伤；（２）在摩擦过程中，金属和     

碳化硅陶瓷摩擦化学磨损机理及磨损图的研究

研究了碳化硅陶瓷自对偶摩擦在空气中从室温到1200℃的摩擦磨损特性、磨损图和摩擦化学。其摩擦学特性与实验温度和载荷密切相关，磨损呈现3种模式：即其比磨损率分别随温度的升高呈现基本不变、增加和减少的规律。在此基础上用磨损图描述了磨损特性和试验温度及载荷等摩擦环境参数的关系。碳化硅陶瓷自对偶摩擦的高温摩擦化学反应产物－无定形SiO2平滑薄膜层的形成与破坏是影响磨损的主要原因。     

Al2O3＋CaF2＋Glass自润滑复合材料摩擦磨损的研究

采用热压烧结工艺研制了Ａｌ２Ｏ３＋ＣａＦ２＋Ｇｌａｓｓ（ＡＦＧ）系列陶瓷自润滑复合材料,并对其室温干摩擦下的摩擦磨损行为及自润滑机理进行了研究。结果表明,适量的润滑相ＣａＦ２粒子分布于硬相Ａｌ２Ｏ３中,能形成有效的减磨层,从而显著降低摩擦系数和磨损因子,是一种良好的减摩抗磨自润滑材料。复合材料磨损过程主要为微剥落。     

Sialon陶瓷干摩擦磨损特性初探

本文研究了销-盘式sialon陶瓷摩擦副的干摩擦磨损随环境温度变化的特性。实验测定了摩擦副在空气中、室温到600℃环境温度下的摩擦系数和磨损因子。用SEM、TEM和X射线衍射技术观察和分析了磨损前后摩擦副的表面形貌、截面特征、磨屑的形状和磨屑及磨痕的相组成。本文试图揭示该材料的摩擦磨损随环境温度变化的特性并初步探讨磨损机理。实验结果表明:sialon陶瓷的主要磨损机理是断裂层离。     

SG—4工程陶瓷加工表面抗磨损性能的研究

本文采用摩擦磨损试验，从的微观结构入手，研究了ＳＧ－４工程陶瓷的磨损同理，并在上基础上讨论了该材料在室温条件下，滑动摩擦时的磨损特征。     

干摩擦条件下Ti（CN）－Al_2O_3复合陶瓷与金属摩擦副的摩擦学特性研究

为了模拟陶瓷刀具的磨损过程，对干摩擦条件下Ｔｉ（ＣＮ）Ａｌ２Ｏ３复合陶瓷与纯铝、纯铁和不锈钢３种金属的摩擦、磨损特性进行了研究。结果表明：随着速度或载荷的增加，摩擦副中金属与陶瓷的磨损量均很快增大。金属的磨损量比对摩的陶瓷的磨损量大得多。３种金属中，铝的磨损量最大，铁和不锈钢的磨损量较小。与铝对摩的陶瓷的磨损量小是由于：（１）铝的硬度小，易剪切，不会对陶瓷造成较大损伤；（２）在摩擦过程中，金属和陶瓷表面之间发生了材料相互转移与扩散，铝在陶瓷表面上的转移量很大，对陶瓷起到了保护作用     

Sialon工程陶瓷抗摩擦磨损性能的研究

本文采用实验的方法，分析了工程陶瓷的摩擦磨损机理，并以此对陶瓷材料在不同载荷及滑动速度下的磨损特性进行了分析和研究。     

润滑剂对Ti（CN）陶瓷摩擦学性能的影响

在销—盘试验机上考察了干摩擦、水润滑及油润滑条件下Ti(CN)/45钢摩擦副的摩擦磨损性能。Ti(CN)陶瓷的磨损主要由粘着剥落和微断裂引起,水对Ti(CN)/45钢摩擦副的摩擦性能无明显改善,但能较明显地减小陶瓷的磨损。油润滑时,摩擦和磨损均得到了明显改善。水和油润滑介质的存在能有效地抑制金属在陶瓷表面的粘着转移,从而降低陶瓷磨损率。采用SEM,XPS,AES等对陶瓷磨痕的分析结果表明,摩擦面上Fe_2O_3的生成对粘着磨损起到了一定的改善作用。油(不含添加剂的液体石蜡)在极压条件下的减磨作用主要是由于其在陶瓷摩擦面上形成了较厚的碳膜(焦质,石墨复合膜)。     

几类典型结构陶瓷材料的冲蚀磨损行为研究

研究了几类典型结构陶瓷材料，如Ａｌ２Ｏ３，ＳｉＣ，Ｓｉ３Ｎ４陶瓷，Ａｌ２Ｏ３－ＺｒＯ２系相变增韧陶瓷（ＺＴＡ，ＴＺＰ）和ＳｉＣｗ／Ｓｉ３Ｎ４系晶须补强陶瓷（ＷＲＳＮ）有９０ｍ／ｓ下的冲蚀磨损性能，以及其与材料性能（硬度，断裂韧性）和冲蚀条件（粒子硬度，冲击角度）之间的关系，分析了冲蚀磨损机制。陶瓷材料的低角冲蚀磨损机制主要包括：研磨状损伤，犁沟状微切削损伤和晶粒剥落。低角冲蚀磨损率随材料硬度的增加     

Friction behavior of PTFE-coated Si3N4/TiC ceramics fabricated by spray technique under dry friction

PTFE coatings were deposited on the Si₃N₄/TiC ceramic substrate by using spray technology. The surface and cross-section micrographs, adhesive force of coatings with substrate, surface roughness and micro-hardness of the coated ceramics were examined. The friction and wear behaviors of ceramic samples with and without coatings were investigated through carrying out dry sliding friction tests against WC/Co ball. The test results indicated that the coated ceramics exhibited rougher surface and lower micro-hardness, and the PTFE coatings can significantly reduce the surface friction and adhesive wear of ceramics. The friction performance of PTFE-coated sample was affected by applied load due to the lower surface hardness and shear strength of coatings, and the main wear failure mechanisms were abrasion wear, coating delamination and flaking. It can be considered that deposition of PTFE coatings is a promising approach to improve the friction and wear behavior of ceramic substrate.     

纳米颗粒增强摩擦材料摩擦学性能研究

以丁腈橡胶改性酚醛树脂为基体,芳纶纤维、玻璃纤维为增强纤维,选用不同类型的纳米颗粒作为填料设计摩擦材料组分配比,并通过热压烧结制备摩擦材料。通过摩擦磨损试验机测试其在干摩擦条件下的摩擦学性能,并用扫描电镜(SEM)对材料的磨损形貌进行观察分析,以研究不同类型的纳米颗粒对摩擦材料性能的影响。研究表明:在干摩擦条件下,经过纳米颗粒改性的摩擦材料摩擦系数、硬度比未改性的材料有不同程度的提高,同时磨损率有很大程度的降低;纳米颗粒改性的摩擦材料摩擦系数、磨损率变化趋势具有一致性,均随着实验载荷、滑动速度的增大而逐渐减小;纳米颗粒改性后的摩擦材料磨损机理表现为疲劳磨损与磨粒磨损并存,而未改性的材料磨损机理主要表现为疲劳磨损。     

Grain-Size and R-Curve Effects in the Abrasive Wear of Alumina

Results of sliding wear tests on three alumina ceramics with different grain sizes are discussed in the light of crackresistance (R-curve, or T-curve) characteristics. The degree of wear increases abruptly after a critical sliding period, reflecting a transition from deformation-controlled to fracture-controlled sulface removal. This transition occurs at earlier sliding times for the aluminas with the coarser-grained microstructures, indicative of an inherent size effect in the wear process. A simplistic fracture mechanics model, incorporating the role of internal thermal expansion mismatch stresses in the crack-resistance characteristic, is developed. The results suggest an inverse relation between wear resistance and large-crack toughness for ceramics with pronounced Rcurve behavior.     

Influence of Rare-Earth Additives on Wear Properties of Hot-Pressed Silicon Nitride Ceramics under Dry Sliding Conditions

The influence of different rare-earth sintering additives (Y, Yb, Lu) on the wear properties of Si₃N₄ ceramics was investigated during sliding contact without lubricant. The kind of rare-earth additives was shown to have a significant effect on the wear behavior for contact sliding under the present testing conditions. Samples sintered with Y₂O₃ as the sintering additive showed evidence of fracture type wear although this was not observed in samples sintered with Yb₂O₃ and Lu₂O₃. These smaller rare earths lead to higher grain boundary bonding strength and superior high-temperature properties and resulted in higher wear resistance. These results showed that the wear properties of Si₃N₄ ceramics could be tailored by judicious selection of the sintering additives.     

Influence of small amount of sintering additives on unlubricated sliding wear properties of SiC ceramics

Fully densified SiC ceramics were developed from commercially available β-SiC powders using small amount (3 wt%) of AlN-Sc₂O₃ or AlN-Y₂O₃ additives by hot pressing at 2050 °C for 6 h in nitrogen atmosphere, and their wear properties were investigated by subjecting to self-mated sliding at different loads (1, 6 and 13 N) under unlubricated conditions. SiC ceramics prepared with 3 wt% AlN-Y₂O₃ additives consisted of mostly large equi-axed grains with amorphous grain boundary phase of ∼1.2 nm thickness, whereas SiC ceramics sintered with 3 wt% AlN-Sc₂O₃ additives showed duplex microstructure of elongated and fine equi-axed grains with clean grain boundary. As the load was increased, the steady state coefficient of friction reduced from ∼0.6 to ∼0.2, and wear rate increased from 10⁻⁶ to 10⁻⁵ mm³/N·m. It was observed that the friction did not depend on the additive composition, while less wear was observed for the SiC ceramics sintered with 3 wt% AlN-Sc₂O₃ additives consisting of clean grain boundary. The material loss was increased with the increased amount of sintering additive to 10 wt%. The worn surface morphology revealed that the material was primarily removed via surface grooving and microcracking at 1 N load, while tribochemical wear dominated at 6 and 13 N loads.     

Effect of Interfacial Layers on Wear Behavior of a Dental Glass-Ceramic

Wear studies on a glass-ceramic dental restorative material were performed under two types of lubrication conditions with distilled water. In one set of experiments, the contact interface was continuously flushed with fresh water to remove the wear debris. In a second set of experiments, the water was not replaced during the testing period. Flushing resulted in a lower friction coefficient and more than twice the wear volume compared with the nonflushing condition. Examination of the worn surfaces in SEM confirmed the presence of an interfacial layer at the sliding interface for the nonflushing experiments. These results suggest that the specific conditions at the sliding interfaces and particularly the nature of interfacial layers must be considered when evaluating the tribological performance of ceramics and especially when the wear data from different studies are compared.     

Sliding wear of CaZrO3-MgO composites against ZrO2 and steel

The wear behaviour of a fine grained and dense CaZrO₃-MgO composite is presented. Un-lubricated Pin-on-disc tests at room temperature have been performed using 10 N as normal force and 0.10–0.15 ms^-1 as sliding rate and ZrO₂ and steel counterparts. The coefficient of friction versus the sliding distance and the specific wear, together with a complete microstructural analysis of the worn surfaces by field emission scanning electron microscopy is reported. The composite presents a wear resistance similar to other ceramics under ceramic/ceramic sliding contact and improved wear resistance in contact with steel.Initial wear is dominated by abrasion independently of the chemical nature of the counterpart. The second stage wear depends on the characteristics of the third body formed. Zirconia leads to a brittle particulate third body with little protective capability. Steel forms a strongly bonded and plastic cermet third body that protects the material limiting the level of further wear.     

载荷、速度及环境温度对聚醚砜酮摩擦磨损性能的影响

利用MM—2000型和THT07—135型摩擦磨损试验机系统考察了载荷、滑动速度和环境温度对含二氮杂萘联苯型聚醚砜酮(PPESUK)摩擦磨损性能的影响，并利用扫描电子显微镜(SEM)观察分析了其磨损表面形貌及磨损机理。研究表明，干摩擦条件下，随载荷增加PPESUK的摩擦系数降低、磨损率增加；在高的滑动速度下，摩擦系数和磨损率都降低；环境温度对PPESUK的摩擦系数影响不大，并且粘着磨损是其主要磨损机理。     

Little amounts of carbon nanotubes as anti-wear reinforcement for alumina in dry sliding

Carbon nanotubes (CNTs) are a leading choice for reinforcing oxide and nitride ceramics, but investigations into the tribological performance of CNT–ceramic composites remain inconclusive. Here, we show that reinforcement with only .1 wt% multi-walled CNTs improves the antifriction and anti-wear performance of zirconia-toughened alumina by up to 23% and 51%, respectively. Dry sliding tests under normal loads of 40–60 N for a sliding distance of 1000 m reveal a load-dependent transition in the lubrication mechanism—CNTs retain their tubular morphology at low loads and reduce friction via a sliding–rolling response, whereas high sliding loads trigger the formation of a uniform, thin lubricating film by the repeated crushing and smearing of exfoliated nanotubes. Raman spectra analyses confirmed that the carbon-rich tribo-film possesses a graphitic structure. Well-dispersed CNTs prevent wear loss by mechanisms, such as crack bridging and grain anchoring. The present work opens up new frontiers for the application of CNT–alumina tribo-ceramics in anti-wear, unlubricated, and high contact stress applications, such as in the manufacturing and mining industries.