蒸馏水润滑下Si3N4—白口铸铁摩擦面上表面膜形成过程 …

为了观察蒸馏水润滑下的Ｓｉ３Ｎ４－白口铸铁摩擦面上表面膜的形成过程,在环－块磨损试验机上进行了不同磨程的磨损试验,通过扫描电镜（ＳＥＭ）对不同磨程的铸铁磨面进行了观察,对表面膜的形成机理进行了初步探讨。结果表明,当Ｓｉ３Ｎ４与白口铸铁配副摩擦时,由于铸铁中碳化物的剥落而形成剥落坑,Ｓｉ３Ｎ４磨屑嵌入剥落坑并氧化和水解,其反应产物富集于剥落坑中,脱水聚合后形成硅胶,从而在磨面形成了含硅胶的表面膜。表     

陶瓷─铸铁摩擦面上形成的表面膜对其摩擦学特性的影响

在Ｍ─２００环─块磨损试验机上研究了陶瓷─铸铁配副在蒸馏水和空气润滑下的摩擦学特性，并以陶瓷─碳钢配副作为对比，对磨损后的试样磨面进行了扫描电镜和光镜观察，采用俄歇电子能谱（ＡＥＳ），Ｘ射线能谱（ＥＤＡＸ）以及图象分析等方法对表面膜进行了分析。结果表明：Ｓｉ３Ｎ４陶瓷与铸铁在蒸馏水润滑下配副获得了非常优异的摩擦学特性，其摩擦系数仅为０．０２，系统的磨损率几乎接近于零，其原因是由于在磨面上形成了具有一定厚度和面积的化学反应膜；当Ｓｉ３Ｎ４与碳钢在蒸馏水润滑下配副时，由于在磨面上不能形成有效的化学反应膜，所以摩擦系数仍然崐较高；当Ａｌ２Ｏ３与金属配副时，在陶瓷磨面上形成了材料转移膜，转移膜的形成大幅度减轻了陶瓷磨损，但却加剧了金属的磨损，并使摩擦系数升高     

陶瓷与灰铸铁在水润滑条件下滑动摩擦学特性的研究

在Ｍ－２００环一块磨损试验机上研究了蒸馏水润滑条件下Ｓｉ３Ｎ４、Ａｌ２Ｏ３陶瓷与灰铸铁（ＨＴ）配副时的滑动摩擦磨损特性，并与这两种陶瓷和０．８％Ｃ钢（Ｔ８）配副相对比；在扫描电镜（ＳＥＭ）下对磨损后的试样表面进行了形貌观察和能谱分析。结果表明：Ｓｉ３Ｎ４／ＨＴ的摩擦系数最小，而且Ｓｉ３Ｎ４与ＨＴ的磨损率均比Ｓｉ３Ｎ４与Ｔ８配副时低得多，其原因是由于在灰铸铁表面形成了一层含石墨的氧化膜；Ａｌ２Ｏ３／ＨＴ与Ａｌ２Ｏ３／Ｔ８的摩擦系数差别不大，但灰铸铁的磨损体积小于Ｔ８。这是由于当Ａｌ２Ｏ３与ＨＴ配副时，很难在ＨＴ表面形成含石墨的表面膜，但ＨＴ中的石墨膜减轻了Ｆｅ向Ａｌ２Ｏ３表面的转移从而降低了磨损。     

电沉积Ni—P—Si3N4复合镀层的磨损机理

通过摩擦磨损试验、Ｘ射线衍射分析和电子探计分析等对电沉积Ｎｉ－Ｐ－Ｓｉ３Ｎ４复合镀层的摩擦损性能及其结构进行了研究，着重分析了Ｎｉ－Ｐ－Ｓｉ３Ｎ４复合镀层的磨损机理。结果表明，在干摩擦条件下，Ｎｉ－Ｐ－Ｓｉ３Ｎ４复合镀层中的Ｓｉ３Ｎ４微粒能够有效地摩擦副之间的犁沟效应和粘着脱落，从而大幅度地提高复合镀层的耐磨性能。     

电沉积Ni－P－Si_3N_4复合镀层的磨损机理

通过摩擦磨损试验、互射线衍射分析和电子探计分析等对电沉积Ｎｉ－Ｐ－Ｓｉ３Ｎ４复合镀层的摩擦损性能及其结构进行了研究，着重分析了Ｎｉ－Ｐ－Ｓｉ３Ｎ４复合镀层的磨损机③。结果表明，在干摩擦条件下，Ｎｉ－Ｐ－Ｓｉ３Ｎ４复合镀层中的Ｓｉ３Ｎ４微粒能够有效地降低摩擦副之间的犁沟效应和粘着脱落，从而大幅度地提高复合镀层的耐磨性能。     

3Al2O3.2SiO2f／Al—Si复合材料磨损机理

本文通过复合材料磨面，磨屑及亚表层的ＳＥＭ特征分析，研究了３Ａｌ２Ｏ３．２ＳｉＯ２ｆ／Ａｌ－Ｓｉ复合材料的润滑衣干滑动磨损机理。润滑状态下复合材料的耐磨性大大优于Ａｌ－Ｓｉ合金，其磨损为纤维断裂与剥落及磨粒磨损；而复合材料在干滑动条件下的耐磨性反而稍差于Ａｌ－Ｓｉ合金，其磨损为粘着磨损，磨粒磨损和层离剥落。     

Ni—P—Si3N4复合镀层的磨损特性

本文通过Ｘ射线衍射分析、电子探针分析和摩擦磨损试验，分析了电沉积Ｎｉ－Ｐ－Ｓｉ３Ｎ４复合镀层的结构性能和磨损特性，并比较了不同弥散微粒的影响。结果表明，在油润滑条件下，复合镀层中的Ｓｉ３Ｎ４微粒在支承载荷的同时，有利于边界润滑膜的形成，避免粘着磨损。同时由于Ｓｉ３Ｎ４微粒本身具有的结构特征，提高了复合镀层的耐磨性能。     

钢与Si3N4摩擦副中边界膜生成机理的探讨

边界摩擦是摩擦副经常出现的一种状态,论述了钢与Ｓｉ３Ｎ４（氮化硅）摩擦副边界润滑机理,指出了在钢表面形成化学反应膜的过程及在Ｓｉ３Ｎ４表面能生成吸附膜,探讨了软金属沉积在Ｓｉ３Ｎ４表层及亚表层从而形成一层软金属润滑层的方法。     

锂基脂润滑下HIP—Si3N4／GCr15配副材料磨损特性试验分析

采用ＭＨＫ－５００型摩擦试验机,在不同锂基脂润滑下,对热静等压氮化硅工程陶瓷（ＨＩＰ－Ｓｉ３Ｎ４）与轴承钢ＧＣｒ１５组成的摩擦副,进行了定量试验研究,并采用ＳＥＭ对磨痕表面形貌进行了分析。     

不同组织高铬白口铸铁低速重载滑动干摩擦磨损行为

对不同化学成分的高铬白口铸铁进行不同热处理,通过低速重载滑动干摩擦磨损试验研究了高铬白口铸铁的磨损率和摩擦因数与摩擦功率密度、正压应力、碳化物类型和基体组织的关系,并探讨了低速重载条件下高铬白口铸铁的滑动干摩擦磨损机理。结果表明:高铬白口铸铁的摩擦因数与碳化物相类型和正压应力有关,而与基体组织无关;磨损率与基体组织类型、碳化物相类型和摩擦功率密度均有关;在低速重载滑动干摩擦磨损过程中,铸铁的组织由摩擦面至内部依次为摩擦层、流变层、应变带、不变区等4个区域;摩擦层中原始基体组织遇到严重破坏,与破碎碳化物充分混合;流变层中固相塑性流变的黏滞阻力增大,导致裂缝、空洞形成,最终产生疲劳剥落;应变带中碳化物相因基体组织的塑性变形而发生弯曲或断裂。     

An investigation on component and formation of tribochemical film in Si3N4-white iron sliding pair lubricated with distilled water

A tribofilm was formed during wear tests of a Si₃N₄-white iron pair lubricated with distilled water. In order to clarify the formation of the film, the wear tests for Si₃N₄-white iron pair with different sliding distances were carried out on a ring-block tester, using distilled water as lubricant. The worn surfaces of white iron specimens were observed under SEM. Furthermore, the component and structure of the film were analyzed by using AES, XPS, FTIR and XRD. From the investigation, the following results are presented. During the wear tests of Si₃N₄-white iron pair lubricated with distilled water, the oxidation and hydrolysis of Si₃N₄ occur on the wearing surfaces, and a tribochemical film, which mainly consists of silica gel, is formed on the wearing surface. The reason for the film formation is that the carbides in cast iron spall off during the wearing tests and the spalling pits are left on the wearing surface of the white iron. Then, the debris of Si₃N₄ or its oxidized product are embedded into the pits, and are further oxidized and hydrolyzed. The products of reactions are concentrated in the pits and polycondensed into silica gel, and a silica gel film is formed on the wearing surface. The film protects both Si₃N₄ and white iron, and makes the paired surfaces smooth. Therefore, the friction coefficient of the pair is down to 0·02, and the wear rates of Si₃N₄ and iron are near zero. However, because the resultants of oxidation and hydrolysis of Si₃N₄ can not be enriched on the wearing surface of carbon steel to form an effective tribofilm, both friction coefficient and wear rate of Si₃N₄-carbon steel pair lubricated with distilled water are still high in value.     

陶瓷与灰铸铁配副在水润滑下的摩擦学性能

比较了在蒸馏水润滑下Si3N4、Al2O3陶瓷与灰铸铁副的摩擦学性能,结果表明：Al2O3陶瓷的磨损体积远小于Si3N4,但与Si3N4配副时灰铸铁的磨损体积明显小于与Al2O3配副时的磨损体积。其摩擦系数也较小（0.02)。用SEM观察发现Al2O3陶瓷磨擦表面粗糙,有少量的转移膜形成;而Si3N4磨擦表面光滑,与其对应的灰铸铁磨面上存在含石墨的润滑膜。     

A study on wear and worn surfaces of grey cast iron affected by a novel silicate additive

A novel aluminium silicate hydroxide additive has shown excellent anti‐wear effect in practical applications and has been mainly studied on steels in laboratory conditions. In this paper, the pin‐on‐disk sliding wear tests were carried out to investigate the wear and worn surfaces of grey cast iron with additives in different concentration. It was found that the silicate additive showed an obvious anti‐wear effect and a reliable duration, reduced the number of pits and cracks on the worn surfaces and improved the nanohardness of the worn surfaces of grey cast iron disks by 72%. Furthermore, Raman spectroscopy displayed that the carbon structure of the worn surface of grey cast iron disks with the additive had an obvious transformation from nanocrystalline graphite to amorphous carbon. Copyright © 2015 John Wiley & Sons, Ltd.     

Tribochemical Behavior of Si3N4–hBN Ceramic Materials with Water Lubrication

The main objective of this article is to study the tribological behavior of Si₃N₄–hBN composites with different hexagonal boron nitride (hBN) volume fraction under distilled water lubrication. Water-lubricated sliding tests were carried out on a pin-on-disc tester, and Si₃N₄ was used as friction pair. The results showed that the addition of hBN to Si₃N₄ resulted in a severe decrease of the friction coefficient, from 0.35 for Si₃N₄ against Si₃N₄ to 0.01 for Si₃N₄-20% hBN against Si₃N₄ with drip-feed water lubrication; the friction coefficients of Si₃N₄–hBN/Si₃N₄ pairs sliding with full immersion water lubrication were as low as 0.01. The morphological and chemical characterization of the worn surfaces were conducted using scanning electron microscopy (SEM), laser scanning microscope, X-ray photoelectron spectroscopy (XPS). The analysis indicated that, with drip-feed water lubrication, hBN in Si₃N₄–hBN was spalled off during the wearing tests and spalling pits were formed on the wearing surface of Si₃N₄–hBN composites, then the wear debris were dropped into the pits and reacted with water, and thus a tribochemical film was formed on the wearing surface. The tribochemical film facilitated the wear surfaces of Si₃N₄–hBN and Si₃N₄ to smooth with drip-feed water lubrication, while the tribochemical remove facilitated the wear surfaces to smooth with full-immersion water lubrication.     

Si3N4-hBN陶瓷复合材料与Fe-B合金配副的摩擦学特性研究

利用MMU-5G销-盘式端面磨损试验机考察Si3N4-hBN陶瓷复合材料与Fe-B合金配副分别在干摩擦和水润滑条件下的摩擦磨损性能,分别采用扫描电子显微镜( SEM)、激光扫描显微镜(LSM)、X光电子能谱(XPS)、X射线能谱(EDS)和X射线衍射(XRD)分析摩擦面及磨屑的形貌与物质组成.结果表明,hBN的加入未能有效地改善Si3N4-hBN/Fe-B合金摩擦副的摩擦学性能,干摩擦条件下,Si3N4-hBN摩擦表面微凸体与Fe-B合金中的硬质相Fe2B发生碰撞而导致脆性断裂和剥落,发生磨粒磨损,摩擦因数均高于0.9,磨损率均高于10-5 mm3/ (N·m)数量级;水润滑条件下,由于水流带走了磨屑,避免磨粒磨损的发生,为Si3N4-hBN摩擦表面发生化学抛光提供条件,化学抛光使销、盘试样的摩擦表面变得光滑,从而获得较为优异的摩擦学性能.     

Unlubricated wear of Si/SiC and its composite with nickel Si/SiC-Ni

Using a pin-on-disk tribometer, dry friction and wear properties at different temperatures were investigated for reaction-sintered silicon carbide Si/SiC and its composites with nickel Si/SiC-Ni. The friction and wear properties of the composites are improved by the addition of nickel. The analysis on the worn surfaces and sub-surfaces by SEM suggest that shallow grooves are the main wear feature at 15°C. At 600°C, surface cracking and fracture is the predominating wear mechanism for Si/SiC, and the formation of flake pits on the surface due to crack propagation at subsurface is the main wear mechanism for Si/SiC-Ni. Finally the relationships between wear resistance and mechanical properties are discussed.     

Influence of Thermal Fatigue on the Wear Behavior of Brake Discs Sliding against Organic and Semimetallic Friction Materials

ABSTRACT

In this article, brake discs are exposed to high thermal stress, causing thermal fatigue damage. The aim of this work is to study the evolution of the wear behavior of brake disc materials, such as cast iron, chromium steel, and metal matrix composites, under the influence of thermal fatigue. The brake disc specimens are heated and then cooled rapidly. Then, wear tests are carried out using a pin-on-disc-type tribometer. Organic and semimetallic friction materials are used for all wear tests. The results show that thermal fatigue affects the structure of the contact surfaces of all of the disc specimens by increasing their roughness. Furthermore, the wear rate of the friction materials increased, except a reduction of the wear rate is noted for the semimetallic friction material rubbing against cast iron. Moreover, thermal fatigue has no significant influence on the coefficient of friction. The worn surface of the metal matrix composite sliding against semimetallic friction material is characterized by abrasive and adhesive wear mechanisms.     

Influence of non-smooth surface on tribological properties of glass fiber-epoxy resin composite sliding against stainless steel under natural seawater lubrication

With the development of bionics, the bionic non-smooth surfaces are introduced to the field of tribology. Although non-smooth surface has been studied widely, the studies of non-smooth surface under the natural seawater lubrication are still very fewer, especially experimental research. The influences of smooth and non-smooth surface on the frictional properties of the glass fiber-epoxy resin composite(GF/EPR) coupled with stainless steel 316 L are investigated under natural seawater lubrication in this paper. The tested non-smooth surfaces include the surfaces with semi-spherical pits, the conical pits, the cone-cylinder combined pits, the cylindrical pits and through holes. The friction and wear tests are performed using a ring-on-disc test rig under 60 N load and 1000 r/min rotational speed. The tests results show that GF/EPR with bionic non-smooth surface has quite lower friction coefficient and better wear resistance than GF/EPR with smooth surface without pits. The average friction coefficient of GF/EPR with semi-spherical pits is 0.088, which shows the largest reduction is approximately 63.18% of GF/EPR with smooth surface. In addition, the wear debris on the worn surfaces of GF/EPR are observed by a confocal scanning laser microscope. It is shown that the primary wear mechanism is the abrasive wear. The research results provide some design parameters for non-smooth surface, and the experiment results can serve as a beneficial supplement to non-smooth surface study.