金属加工中的摩擦化学反应与节能润滑技术

论述了金属加工中的表面摩擦化学反应、润滑剂浓度和反应活性与腐蚀磨损的关系及其边界极压润滑效果。提出了金属切削加工和成形加工中的一些节能润滑技术。     

织构化刀具切削性能测试及切削温度仿真分析

研究织构化硬质合金刀具对切削Ti6Al4V钛合金性能的影响。在干切削和低温微量润滑(CMQL)条件下,通过开展无织构和织构化刀具切削试验,分析不同刀具在不同润滑条件下切削力和摩擦因数变化规律。结果表明:微沟槽刀具在CMQL条件下的切削性能最好,在干切削条件下的切削性能最差,表明微沟槽在CMQL条件下能有效改善刀具的摩擦学性能,而在干切削条件下反而增大了刀具的摩擦磨损。通过仿真分析织构化刀具高速干切削条件下的切削温度,结果表明:织构化刀具干切削条件下的切削温度高于无织构刀具,这是因为表面织构增大了刀具表面的粗糙度,加剧了刀-屑界面摩擦。     

干摩擦和水润滑条件下单晶硅的摩擦磨损性能研究

在UMT-2微摩擦试验机上,对单晶硅片进行了干摩擦和水润滑两种状态下的摩擦磨损试验,分析讨论了载荷和滑动速度对单晶硅片的摩擦因数和磨损率的影响规律;运用扫描电子显微镜,观察和分析了其磨损表面形貌。结果表明:干摩擦条件下的磨损机理主要表现为黏着磨损,水润滑条件下的磨损机理主要表现为机械控制化学作用下的原子/分子去除过程;水润滑条件下的摩擦因数和磨损量均较小,最小磨损率仅为10μm3/s;在水润滑条件下,载荷和滑动速度达到一定值时,硅片表面将发生摩擦化学反应,生成具有润滑作用的Si(OH)4膜,即机械作用在一定条件下对化学反应具有促进作用。     

氧化铝陶瓷在海水润滑下的摩擦学行为研究

采用UMT-3摩擦实验机研究氧化铝陶瓷在海水润滑条件下的摩擦学行为,并与其在干摩擦和纯水润滑条件下的摩擦学行为进行比较。利用扫描电子显微镜和X-射线光电子能谱观察并分析氧化铝陶瓷磨损表面形貌以及磨损表面主要元素的化学状态,探讨氧化铝陶瓷在海水中的摩擦化学特性。结果表明,氧化铝陶瓷在干摩擦时具有最大的摩擦因数和最小的磨损率,在海水润滑条件下具有最小的摩擦因数和最大的磨损率,这是氧化铝在海水中发生了摩擦化学反应的结果。氧化铝陶瓷在干摩擦时的磨损主要表现为轻微的脆性剥落,在纯水润滑条件下表现为严重的脆性剥落,而在海水润滑条件下表现为摩擦化学磨损以及极轻微的脆性剥落。     

基于固体润滑剂与原位反应双机制自润滑陶瓷刀具

采用真空热压烧结工艺,以Al2O3/TiB2为基体、CaF2为添加剂制备了Al2O3/TiB2/CaF2(ABF)自润滑陶瓷刀具,并对其进行了摩擦磨损试验和淬硬钢干切削试验。在摩擦磨损试验过程中,测定了4种不同CaF2含量的ABF陶瓷材料样品。摩擦磨损试验结果表明,ABF材料的平均摩擦因数随着CaF2含量的增加而减小,这是因为固体润滑剂CaF2在磨损过程中生成的润滑膜起到了一定的减摩作用。将ABF刀具和普通陶瓷刀具(AG2)在120 m/min切削速度下对45淬硬钢进行干切削试验,切削试验结果表明,ABF前刀面的平均摩擦因数比AG2陶瓷刀具前刀面的平均摩擦因数要显著偏小,主要原因是ABF自润滑陶瓷刀具在高速切削时,固体润滑剂CaF2和自身TiB2的原位反应同时生成了润滑膜,这种双重机制下生成的润滑膜具有极佳的润滑性能,其润滑效果随温度和切削速度的增加而显著提高。     

海水润滑赛龙材料磨损机制分析

试验研究海水润滑条件下赛龙材料的摩擦磨损性能,借助表面形貌仪、扫描电镜分析磨痕表面形貌,分析海水润滑条件下赛龙材料的磨损机制,并与干摩擦、湿润滑条件下的磨损机制进行比较。结果表明:干摩擦条件下表现为黏着磨损和磨粒磨损特征;湿润滑条件下磨损表现为微切削(磨粒磨损);海水润滑条件下的磨损中有气蚀磨损、磨粒磨损共同存在。     

JQ—1切削剂的效用和使用效果

JQ-1切削剂是由广州机床研究所研制、广东顺德县桂洲红旗润滑材料厂生产的一种新颖润滑剂。它的大致成分如表1所示,含有氯、磷极压剂、油性添加剂和非离子型表面活性剂等。这些物质在切削区高温高压作用下会发生化学反应,生成诸如氯化铁、氯化亚铁、氯氧化铁、磷酸铁等反应膜,增强了切削液的润滑作用和抗压强度,使刀具前刀面和切屑之间、刀具后刀面和切削面之间实现边界润滑(即边界摩擦),避免了于摩擦,从而利于切削加工和     

在刀-屑界面持续润滑刀具切削45钢的性能及润滑机理

为提高刀具润滑性能,尽量减少切削液的使用,制备出在刀屑界面持续润滑的新型刀具,能够将切削液通过微通道直接输送到刀屑接触界面内部。采用该新型刀具与普通刀具在干切削和浇注切削液条件下分别进行切削45钢试验,测量了切削三向力,对刀具前刀面磨损面进行SEM微观形貌分析及元素检测,分析了刀具的摩擦磨损特性及润滑机理。试验结果表明,与普通刀具在干切削和浇注切削液条件下相比,刀屑界面持续润滑刀具能够有效减少切削过程中的摩擦磨损,而切削液用量只有传统浇注式切削的1/120。分析前刀面的元素可知,切削液能够更加深入到离主切削刃更近的区域,并能持续供给,这是该刀具具有更好的减摩抗磨效果的主要原因。尽管新型刀具的黏结情况大大缓解,但刀具的磨损机理仍然以黏结磨损和氧化磨损为主。     

高温自润滑陶瓷刀具材料及其切削性能的研究

以TiB2为添加剂,Al2O3为基体,制备了Al2O3/TiB2陶瓷刀具材料。以该陶瓷刀具对淬硬钢进行高速干切削试验,利用其在切削高温作用下的摩擦化学反应,在刀具材料表面原位生成具有润滑作用的反应膜,从而实现Al2O3/TiB2陶瓷刀具材料本身的高温自润滑。研究了Al2O3/TiB2陶瓷刀具在切削高温作用下刀具表面的摩擦化学反应机理,分析了刀具表面自润滑膜的组成结构。结果表明：Al2O3/TiB2陶瓷刀具在干切削淬硬钢时,当切削速度大于120 m/min时,开始表现出高温自润滑性能。自润滑膜的组成为Al2O3/TiB2陶瓷刀具中TiB2的氧化产物,它能在刀具表面起到固体润滑剂的作用,进而降低前刀面的摩擦因数,减轻刀具的粘着磨损,提高刀具的耐磨性能,具有良好的减摩和抗磨作用。     

高速车削中低温最小量润滑方式的冷却润滑性能

基于复合制冷技术研制一种低温最小量润滑供给装置,分析低温最小量润滑切削的冷却润滑作用,通过干切削、常温冷风、最小量润滑(Minimum quantity lubrication,MQL)、低温冷风、低温最小量润滑(低温MQL)5种冷却润滑条件下高速车削钛合金的切削温度、切削力对比试验,研究低温MQL在高速车削中的冷却润滑性能。结果表明,5种冷却润滑条件中,低温MQL能够最有效降低切削温度,且随着切削速度的提高,其降低切削温度的效果更明显;低温MQL优异的冷却效果有益于微量润滑油润滑作用的发挥,使其对切削区的润滑效果优于MQL,有效地降低高速车削钛合金时的切削力,改善刀具前刀面摩擦状况。     

高速干切削技术及其实现

在切削加工中大量使用切削液进行冷却、润滑,不但提高了加工成本,也带来了环境污染,消除这些问题的合理措施是采用高速干切削方式。提出了干切削技术的新内涵,分析了实现高速干切削的机床技术、刀具技术和工艺技术。通过该技术实现了绿色制造,保证了企业的经济效益和社会效益最优化。     

Experimental assessment of textured tools with nano-lubricants in orthogonal cutting of titanium alloy

In this study, we investigated the effects of composite nano-Cu/WS₂ lubricating oil and single-point diamond indentation-textures on improving the cutting performance of YG8 cemented carbide tools, which is crucial for textures tool applications. The aims of the study were to improve wear resistance and reduce chip adhesion at the tool’s rake face in cutting of titanium alloys. Dot textures with different spacings were fabricated on the surface of YG8 cemented carbide tools through the single-point diamond indentation method, and composite nano-Cu/WS₂ lubricating oil was prepared. Orthogonal cutting tests were carried out under dry cutting and minimal quantity lubricated (MQL) conditions. Investigate the effect of different texture spacing on the cutting performance in the light of cutting forces, friction coefficient, the deformed chip thickness, tool adhesions, and chip morphology. The results show that the dot texture effectively improved the lubrication conditions in machining titanium alloys under the MQL conditions. The dot texture is effective at low speed in the dry cutting conditions. With the increase of cutting speed, the friction coefficient of dot texture tool is affected by texture spacing, and the friction coefficient of DT-200 tool is the smallest. In addition, composite nano Cu/WS₂ lubricating oil forms a lubricating film on the wear path by atomizing the lubricating oil and stores it in the dot texture, which enhances the anti-wear performance in the cutting process and reduces the cutting force and friction coefficient at the tool chip interface. By evaluating cutting force, friction coefficient, chip and tool morphology, it is concluded that DT-100 tool is more effective in improving lubrication conditions.

     

Study of the Conductivity and Tribological Performance of Ionic Liquid and Lithium Greases

Ionic liquid (IL) lubricating greases were prepared using 1-hexyl-3-methylimidazolium tetrafluoroborate and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl) amide as base oil and polytetrafluoroethylene (PTFE) as thickener, respectively. Three kinds of lithium greases were also prepared using lithium ILs ([Li(PAG)]X) as base oil and PTFE as thickener. 1-Ethyl-3-methyl imidazolium hexafluorophosphate as an additive was added to the PAG grease, which was prepared using polyalkylene glycol monobutyl ether (PAG) as base oil and PTFE as thickener. The conductivities and tribological properties of the prepared lubricating greases were investigated in detail. Scanning electron microscopy and X-ray photoelectron spectroscopy were employed to explore the friction and wear mechanism. The results showed that the IL and lithium lubricating greases have conductivities and excellent tribological properties. Especially, IL greases have the highest conductivity. The excellent tribological properties are attributed to the formation of boundary films consisting of both tribo-chemical reaction films and physical absorption films, while high conductivities are attributed to the intrinsic electric fields of the ILs.     

添加固体润滑剂的自润滑陶瓷刀具材料及其减摩机理研究

采用热压工艺制备Al2O3/TiC/CaF2(ATF)自润滑陶瓷刀具材料,考察其室温下的机械性能,并通过切削性能试验分析其切削减摩机理。结果表明:添加固体润滑剂对陶瓷材料的机械性能有一定影响,其中CaF2含量为10%的Al2O3/TiC/CaF2陶瓷材料的力学性能最好,强度和硬度最高,分别达到了589MPa和HV15·4GPa,可以用作刀具材料;ATF自润滑陶瓷刀具在切削过程中,减摩性能优于LT55陶瓷刀具,能够在前刀面形成一层较完整的固体润滑膜,膜的存在使得ATF自润滑刀具材料具有一定的减摩能力,而后刀面具有磨粒磨损的特征,由于磨粒的刻划作用而没有形成较完整的润滑膜。     

Tribochemical Surface Reaction and Lubricating Oil Film

A radioactive tracer technique was used to investigate a tribo-chemical surface reaction obtained by a thrust collar type friction Machine. Radioactive dibenzyl disulfide labeled with sulfur-35 was used as an additive. Steel and copper disks were used as friction specimens.

Radioactive copper sulfide on the friction surface was quantitatively measured with a G-M tube, and a kinetical analysis of the reaction was carried out.

The friction coefficient decreased linearly depending on the amount of surface produced on the friction surface. This dependency was accompanied by adsorption of dibenzyl disulfide, which made a more effective lubricating oil film and was enhanced by the sulfide on the friction surface.

The results of kinetical analysis were explained effectively by considering the oil film behavior related to the adsorptive action of the surface sulfide.     

Tribological aspects of tool-chip and tool-work contact in machining and the application of laser spectrometry

Results from the first attempt to use the laser ablation inductively coupled plasma time of flight mass spectrometry (LA-ICP-TOFMS) in the analysis of tribo-chemical layers associated with metal cutting operations are presented here. It was possible to identify the inclusion products from adhering work material at the tool-chip contact in turning 316L stainless steel with cemented carbide tools. Similarly, laser spectrometry was able to quantify Pb enrichment of the surface layer of brass specimens resulting from turning. Thus, this technique opens new possibilities for the quantitative investigation of tribo-chemical layers associated with friction pairs in general and metal cutting operations in particular.     

低温氮气射流对钛合金高速铣削加工性能的影响

在钛合金的高速切削过程中，切削区温度很高，加速了刀具的磨损，限制了切削速度的进一步提高。为降低切削区温度、防止刀具的氧化磨损，提出在低温氮气射流条件下进行钛合金的高速铣削加工。在干铣削、浇注切削液、常温氮气油雾、低温氮气射流和低温氮气射流结合微量润滑等冷却润滑条件下进行了钛合金的高速铣削对比试验。试验结果表明，低温氮气射流结合微量润滑能够最有效地降低铣削力，抑制刀具磨损。借助扫描电镜的检测手段，研究了不同冷却润滑条件下刀具的失效形式。指出在低温氮气射流条件下高速铣削钛合金时，只要热裂纹的形成与扩展未引起刀具的崩刃及刀面的剥落，进一步降低低温氮气的温度将提高刀具的使用寿命。     

Preparation of tungsten disulfide (WS2) soft-coated nano-textured self-lubricating tool and its cutting performance

This paper proposes a new effective dry cutting tool named tungsten disulfide (WS₂) soft-coated nano-textured self-lubricating tool which is fabricated by two steps. First, nano-texture is made on the tool–chip interface of rake face of uncoated YS8 (WC + TiC + Co) cemented carbide cutting inserts by femtosecond laser micromachining technology. Second, WS₂ soft coating is deposited on the nano-textured tool by medium-frequency magnetron sputtering, multi-arc ion plating and ion beam assisted deposition technique. Dry turning tests on 45# quenched and tempered steel were carried out with three kinds of cutting tools: conventional YS8 tool, nano-textured tool (CFT), and WS₂ soft-coated nano-textured self-lubricating tool (CFTWS). Results show that the cutting forces, cutting temperature, the friction coefficient at the tool–chip interface, and the antiadhesive effect of the nano-textured tools were significantly reduced compared with those of the conventional one. The CFTWS tool had the best cutting performance among all the tools tested under the same test conditions. Through cutting force and cutting temperature theoretical analysis and experimental results, four mechanisms responsible were found. The first one is explained as the formation of the WS₂ lubricating film with low shear strength at the tool–chip interface, which was released from the surface nano textures and smeared on the rake face, and served as lubricating additive during dry cutting processes to reduce the cutting forces and cutting temperature. The second one is explained by the reduced contact length at the tool–chip interface of the nano-textured tools; the smaller direct contact area between the chip and tool rake face leads to less friction force, which can also contribute to the decrease of cutting forces and cutting temperature. The third one can be explained that because of the excellent lubricity of the WS₂ lubricating film, the antiadhesive effect can be significantly improved which can reduce adhesive wear of the cutting tool and prolong the tool life. The fourth one can be explained that the advantage of CFTWS tool in cutting forces and cutting temperature is obvious in relatively high-speed and high-temperature conditions may be because of ultra-low friction coefficient, high temperature resistance, and the high oxidation resistance of WS₂ soft coating which is not sensitive to high cutting temperature and high cutting speed can significantly improve the severe dry cutting environment.     

超声波处理乳化液在金属切削中的试验研究

为了研究超声波处理对乳化液冷却润滑性能的影响,设计了用于切削试验的乳化液超声波处理系统,并在干切、未采用超声波处理乳化液和采用超声波处理乳化液三种条件下,采用YT15刀具车削45钢进行了对比试验。结果表明：使用超声波处理乳化液时,切削力可比干切和未采用超声波处理乳化液时分别减小10%~15%和5%~10%;变形系数也减小了,切屑形貌得到改善。通过测量液体粒度可知,超声波处理使乳化液的分子团粒径减小,乳化液进入切削区毛细管的可能性增大,说明超声波处理能够提高乳化液的冷却润滑作用效果,也可理解为间接地减少了乳化液的用量,有利于节能减排。