CrMoV合金堆焊层组织结构及抗冲蚀磨损性能研究

采用手工电弧焊工艺在20钢基体表面制备CrMoV合金堆焊层进行相组成、显微组织、耐冲蚀磨损性能及冲蚀磨损机理研究。结果表明,堆焊层数增加母材稀释率减小,堆焊层显微组织主要为马氏体、残余奥氏体及合金碳化物。第二、三堆焊层显微硬度最高,堆焊层平均显微硬度达780 HV,为基体硬度的4倍多。在所有冲蚀角度范围内,CrMoV合金堆焊层耐泥沙冲蚀磨损性能优于20钢;冲蚀角度小于30°时冲蚀磨损机制以微切削为主,大于30°时以疲劳损伤及局部塑性变形为主;砂粒粒径增加,堆焊层及20钢的冲蚀磨损率均有所增加,但不与粒径的增加值成正比。     

电弧喷涂铁基非晶涂层的制备及其冲蚀磨损性能研究

为了筛选最佳的铁基非晶涂层制备工艺和研究涂层的冲蚀磨损机理,采用电弧喷涂技术在不同工艺参数下制备Fe基非晶态合金涂层,利用自制固液两相流冲蚀磨损试验机和电化学工作站对涂层的耐磨损、耐腐蚀性能进行研究;并用X射线衍射仪(XRD)、扫描电镜(SEM)等手段观察分析了涂层的相结构和组织形貌。结果表明:非晶涂层结构致密、组织均匀,并具有典型的层状结构;铁基非晶涂层具有良好的耐冲蚀性能,90°攻角下涂层冲蚀失重要高于30°攻角下涂层的失重;电弧喷涂电压上升,涂层冲蚀失重随之减小;送丝速度增加,涂层冲蚀失重先降低再升高;冲蚀磨损机制主要表现为脆性剥落;非晶涂层的耐腐蚀性能随喷涂电压的上升得到提高,随送丝速度增加先增强再减弱。     

粘结相含量对超音速火焰喷涂Cr_3C_2-NiCr涂层冲蚀磨损的影响

采用不同粘结相含量的粉末,运用超音速火焰喷涂方法制备了Cr3C2-NiCr涂层。运用干砂冲蚀磨损试验机检测不同冲蚀角度下涂层的冲蚀磨损性能,研究粉末粘结剂含量对沉积涂层冲蚀磨损性能的影响。运用扫描电镜技术观察并分析Cr3C2-NiCr涂层冲蚀磨损失效行为。结果表明:粘结相含量不同的HVOF喷涂涂层均表现出脆性材料的冲蚀磨损特性,随冲蚀次数的增加失重量呈近似线性增加;粘结相在涂层中的分布形式影响涂层的抗冲蚀性能,但不改变冲蚀失效的主要机制。     

氮合金化堆焊硬面合金的抗冲蚀磨损性能研究

利用氮代替部分碳,通过铌、钒、钛固氮形成氮合金化堆焊硬面合金,进行了冲蚀角度30°抗冲蚀磨损性能实验,深入分析了冲蚀磨损机理。结果表明:高速含砂水流的冲击磨损,对硬面合金产生明显切削和犁沟剥落,其磨损机制主要为微切削磨损。氮合金化堆焊硬面合金中碳氮化物沿马氏体基体和晶界弥散析出,在强化基体金属提高硬度的同时能有效抵御冲蚀粒子的切削,增强抗冲蚀磨损性能,其磨损特征表现为冲蚀粒子冲击后留下的切削、犁沟以及碳氮化物处造成的块状剥离。     

挟沙风作用下风力机叶片涂层冲蚀特性研究

内蒙古中西部地区高频出现沙尘暴活动,风力机叶片涂层长期被挟沙风冲蚀磨损,导致风力机叶片涂层出现冲蚀坑和裂纹,缩短风力机叶片寿命。针对这一问题,利用自制的挟沙风试验台,采用气流挟沙喷射法对以环氧玻璃纤维板为基底的风力机叶片涂层进行低角度加速冲蚀磨损试验,用失重测量法测定冲蚀磨损量与冲蚀速度的关系,用扫描电镜(SEM)观测分析涂层表面的冲蚀形貌来确定冲蚀机理,并提出涂层冲蚀磨损程度的评价计算公式。结果表明:涂层的冲蚀磨损量随着冲蚀速度的增大而增加;低角度冲蚀以微切削冲蚀磨损作用为主,材料的硬度起着决定性作用,高角度冲蚀主要以挤压变形冲蚀磨损为主,材料的韧性起决定性因素,由于聚氨酯涂层材料是塑性材料,其韧性高而硬度低,故在低冲蚀角下冲蚀磨损量大;验证了评价计算公式用于评价涂层冲蚀磨损程度的可靠性,为运行在风沙环境下的风力机叶片涂层的改进提供理论依据。     

氮气钻井过程中的耐冲蚀涂层

将多功能四通制造材料30CrMo钢作为基体材料,使用氩弧焊制备钴基合金HS113,625,Co-112堆焊层,采用喷焊方法制备Ni60涂层,使用超音速火焰喷涂(HVOF)方法制备WC-12Co涂层。对该5种涂层的冲蚀行为使用自制的冲蚀试验机进行了研究,分析了显微组织与显微硬度对冲蚀性能的影响及涂层冲蚀后的表面形貌。结果表明:涂层的冲蚀失重与减薄均随冲蚀时间线性增加,HS113涂层的耐冲蚀性要优于其他4种涂层的耐冲蚀性;显微组织、硬度等均会影响涂层的耐冲蚀性能。     

激光熔覆FeCrNiCoCuAlx高熵合金涂层的耐腐蚀与抗冲蚀性能

采用激光熔覆技术在Q345钢表面制备FeCrNiCoCuAl_x(x=0, 1, 2, 3)高熵合金涂层。通过XRD,SEM及冲蚀磨损等实验方法研究高熵合金涂层的组织结构与性能。结果表明:随着Al含量的增加,高熵合金涂层由简单结构的FCC和BCC混合固溶体逐渐转变成全部的BCC结构,涂层的硬度也随之增大,最高可达580HV。在3.5%NaCl溶液中,涂层的腐蚀电流密度随着Al含量的增加先降低后提高,且当x=1时涂层具有最好的耐蚀性。冲蚀磨损实验表明,当冲蚀角度由90°减小到30°时,冲蚀磨损量不降反升,表现出韧性材料的冲蚀特征。涂层的抗冲蚀性能随着Al含量的增加而增强,且冲蚀磨损机制由锻造挤压转变为以微切削和犁削为主。     

反应等离子喷涂TiC/ Fe-Ni复合涂层及其耐冲蚀性能

以TiFe粉、Ni粉和蔗糖(碳的前驱体)为原料,通过蔗糖的热分解碳化制备Ti-Fe-Ni-C系反应热喷涂复合粉末,并利用等离子喷涂制备了TiC/Fe-Ni复合涂层。复合涂层主要由TiC颗粒均匀分布于(Fe、Ni)固溶体中形成的复合强化片层构成,片层中TiC颗粒呈球形或近球形,粒度为亚微米级和纳米级。TiC/Fe-Ni复合涂层的耐冲蚀磨损性能研究表明：涂层冲蚀失重率随攻角的增大而增加,表现出脆性材料冲蚀特性,但冲蚀失重率对攻角不敏感,涂层具有较好的塑性与硬度的配合;复合涂层的耐冲蚀磨损性能优于相同工艺条件下制备的C_r2C₃/Ni-Cr复合涂层,约为20G钢的2倍以上。     

材料抗冲蚀性的研究进展

综述了材料内在因素和环境因素变化对冲蚀的影响,韧性材料的耐冲蚀性能优于脆性材料,脆性材料仅在10^0冲蚀角以下才表现出较好的耐冲蚀性;冲蚀下的脆性材料和塑性材料的区分不仅与材料的韧脆性有关,还与冲击粒子的动能有关。当粒子质量发生变化时,材料的冲蚀机理随之变化;影响材料耐冲蚀磨损的重要内在因素是弹性模量而不是硬度;各种冲蚀机理都有一定的适应性和局限性。     

微/纳米复合涂层的抗冲蚀磨损性能

为了修复在冲蚀磨损环境下流体机械的过流部件,在分析过流部件冲蚀磨损机理的基础上,优选微/纳米颗粒填料对有机复合弹性涂层的黏性底层和抗冲蚀橡胶层进行优化设计,模拟现场工况利用转盘式磨损实验装置对涂覆该涂层的试件以及另外四种不同表面处理方法的试件进行耐冲蚀磨损性能实验,并采用失重法和扫描电镜(SEM)对冲蚀磨损结果进行了分析和对比。结果表明:经过35h的冲蚀磨损后,所研究的五种不同表面处理方法处理后的试件在冲蚀磨损过程中的质量变化规律相同,微/纳米复合涂层具有最佳的耐冲蚀磨损性能,基本没有失重,而用胎体粉涂覆的试件耐冲蚀磨损性能最差,说明该涂层能有效修复过流部件并提高过流部件的抗冲蚀磨损能力。     

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.