航空发动机可磨耗封严涂层技术研究及性能评价EI北大核心CSCD

综述了国内外封严涂层的研究现状,介绍了航空发动机封严涂层的结构和应用特点,重点讨论了可磨耗封严涂层性能评价和技术研究现状。比较了各种涂层材料、评价方法的优势与不足,指出了可磨耗封严涂层的应用潜力及研究发展方向。提出了我国在可磨耗封严涂层技术研究及性能评价方面今后的发展方向,即涂层制备方法、结构研究、高温涂层研究和仿真技术等。     

基体结构对Al/BN涂层性能的影响

Al/BN涂层是一种适用于450℃以下的可磨耗封严涂层,常应用于燃气轮机压气机部位的气路封严。等离子喷涂Al/BN涂层在机械加工后常出现涂层表面疏松及涂层表面粗糙度不均匀的现象,在服役过程中会出现不可预料的涂层脱落以及粘附叶片等现象,影响发动机性能和可靠性。本文针对等离子喷涂Al/BN可磨耗封严涂层开展热喷涂工艺研究,对涂层显微组织、拉伸结合强度、硬度等性能检测及评价,并着重研究基体材料结构对涂层性能的影响,结果表明相对于平板试片,带有螺纹结构试片的涂层结合强度稍高,但其Al/BN涂层与底层厚度不均匀,造成结合强度值波动较大。     

新型高温隔热可磨耗封严涂层研究及展望

介绍了可磨耗封严涂层和热障涂层的研究现状.通过对二者发展共性的探讨.提出了开发一种广泛应用于燃气轮机及航空发动机部件上,既具有高温隔热性能又具有高温可磨耗性能的新型涂层.该新型涂层通过热障涂层的工作方式,能有效提高发动机部件的使用温度,并能以可磨耗封严的工作方式改善发动机的密封性能,最终大幅度提高发动机的燃气效率及使用寿命.通过对该新型涂层的概念、结构特点、实现方法以及优异性能的系统分析,指出了新型高温隔热可磨耗封严涂层的应用潜力及研究发展方向.     

抗剥落金属基可磨耗封严涂层结构匹配制备研究

新一代航空发动机对推重比提出更高的要求,而发动机叶尖与机匣的间隙是影响发动机效率的关键因素之一。在机匣内壁制备可磨耗封严涂层能有效减小气流泄漏、避免叶尖与机匣碰磨,从而使发动机高效、安全地运行。可磨耗封严涂层通常具有高孔隙率,然而高孔隙率易降低可磨耗面层/陶瓷隔热层界面强度,引发可磨耗涂层整体剥落。为此,开展可磨耗封严面层/陶瓷隔热层界面结构匹配设计,在保证涂层可磨耗封严功能的基础上,增强二者界面抗剥落能力。首先,通过数值分析方法发现,可磨耗层/陶瓷层界面处孔隙特征尺寸和孔隙率增加均会加剧可磨耗层沿界面剥落的风险。进一步,提出可磨耗封严涂层的结构匹配设计,即在靠近界面处增加抗剥落过渡层。最后,通过模拟和试验相结合,优化抗剥落过渡层厚度,证实过渡层可显著延长体系的服役寿命。     

封严涂层性能评定的新方法

利用研制成功的新型电子冲击刮削试验发现，可测试航空发动机封严涂层的冲击载荷－位移曲线，由此得出的屈服载荷点、最大载荷点、冲击刮削韧性等参数可用于定量综合评估封严涂层的可磨耗性、抗冲蚀性以及涂层与基体结合强度。     

模拟服役条件下镍-石墨涂层的可磨耗性研究

火焰喷涂镍石墨封严涂层广泛应用于高压压气机前对开机匣和其他航空发动机零件上,其目的 是通过与叶尖或蓖齿之间的磨削控制转子与机匣壳体之间的间隙,从而提高发动机的效率,降低燃油消耗率,可磨耗性是评价封严涂层性能的重要指标之一.根据航空发动机设计的迫切要求,开展了模拟工况下镍-石墨涂层的摩擦磨损试验,并对涂层的可磨耗性进行了深入研究,分析了切削深度、切削速率等因素对涂层可磨耗性能的影响机制.结果 表明:在相同叶尖线速度下,切削深度对涂层磨损的影响比切削速率的影响更为显著;镍-石墨涂层在高线速度下的主要摩擦磨损机制是塑性变形和摩擦氧化;环境温度对涂层的摩擦磨损有一定的影响.     

金相试样制备技巧及具体方法

合理的金相试样制备方法是获得清晰、高质量显微组织图像的保障,是材料金相研究的基础。对高纯钨、高氮不锈钢、汽车钢板、涂层材料的金相制备技巧及具体方法进行了分析,解决了制样中切割、镶嵌、磨抛和浸蚀等过程遇到的问题。结果表明:高纯钨硬度高,要保证磨抛时间;高氮不锈钢采用三氯化铁盐酸甘油混合液浸蚀,可获得浸蚀均匀的显微组织形貌;汽车钢板制样时要保证试样直立,不倾斜,且要避免抛光过程产生划痕;涂层材料制样的切割、镶嵌和磨抛过程要做好防护工作,确保涂层完整。     

防钛火金属/陶瓷阻隔层设计与制备方法

金属/陶瓷阻隔层不仅可用于防钛火可磨耗封严涂层起阻燃作用,还可用于航空发动机热部件的热障涂层.以航空发动机压气机防钛火涂层的应用为主要背景,对金属/陶瓷阻隔层体系结构设计、涂层材料以及制备方法进行了系统的阐述.在涂层材料层面,分别介绍了陶瓷层与金属粘结层的材料成分设计、性能特点及其合成方法.在涂层制备技术层面,主要阐述了等离子喷涂(PS)、电子束物理气相沉积(EB-PVD)以及新型的等离子物理气相沉积(PS-PVD)3种方法.最后,面向防钛火涂层的发展需求,提出了金属/陶瓷阻隔层未来在材料升级、工艺优化、性能表征以及涂层技术理论体系等方面的发展方向.     

封严涂层材料及应用

介绍了封严涂层的特点、测试方法、分类以及国内外可磨耗和耐磨封严涂层的应用情况,对部分封严涂层材料的发展过程及涂层的特殊制备工艺进行了阐述。评述了封严涂层的研究现状及在航空工业的发展前景。     

基于硅树脂的封严涂层的制备及其性能研究

为开发航空发动机使用的无金属填料的低温封严涂层(300～300℃)并提高飞机发动机密封涂层的使用温度,制备了基于甲基苯基硅树脂的密封涂层.采用氯硅烷共水解的方法合成了具有高热稳定性的甲基苯基硅树脂,并采用傅里叶红外光谱(FTIR)、差式扫描量热(DSC)和热重分析法(TGA)表征了其结构、固化行为和热稳定性;理想的涂层组成为:硅树脂∶石墨∶氮化硼∶石棉(质量比)= 50 ∶ 15∶ 5 ∶ 15,以合成的甲基苯基硅树脂为基体树脂,添加石棉、石墨和氮化硼作为填料制备了封严涂层,对其综合性能进行了分析.所得结果显示:涂层于400℃老化100 h后,粘结强度仍达到10 MPa以上;涂层具有良好的耐热冲击性,在400℃～室温之间的冷热循环次数可达50次以上.该涂层经考核验证,可以满足某型号航空发动机对低温封严涂层的要求.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Study on Bond Ability of Arc-Spraying Coatings with Different Surface Pretreatment on Cast-Iron

Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.     

Evaluation of fatigue life of steel using steel grain size

The insightful discussion of the relationship between the construction of metallographic and fatigue life and proposition of mathematical relationships describing this relationship was conducted in the paper. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the grain size and the participation of ferrite and pearlite phase.