激光熔覆镍、钴基涂层性能比较研究

通过激光熔覆获得三种大块镍或钴基熔覆涂层,并对其在10g/L、20g/L和30g/L硫酸溶液中的腐蚀性能进行了比较研究.结果表明,在各种硫酸溶液中1#镍基涂层的腐蚀电流/腐蚀速率最大,3#钴基涂层的最小,2#镍基涂层的和3#钴基涂层接近.随着稀硫酸浓度的增加,激光熔覆的镍、钴基涂层的耐腐蚀性能有下降趋势.钴基涂层的相对耐磨值是1#镍涂层的19.0倍和2#镍基涂层的37.7倍.     

激光熔覆镍弋钴基涂层性能比较研究

通过激光熔覆获得三种大块镍或钻基熔覆涂层,并对其在10g／L、20g／L和30g/L硫酸溶液中的腐蚀性能进行了比较研究。结果表明,在各种硫酸溶液中1^#镍基涂层的腐蚀电流／腐蚀速率最大,3^#钴基涂层的最小,2^#镍基涂层的和3^#钴基涂层接近。随着稀硫酸浓度的增加,激光熔覆的镍、钴基涂层的耐腐蚀性能有下降趋势。钴基涂层的相对耐磨值是1^#镍涂层的19．0倍和2^#镍基涂层的37．7倍。     

激光熔覆镍、钴基涂层腐蚀性能比较研究

本文通过激光熔覆获得了3种大块镍或钴基熔覆涂层,并对其在10g/L、20g/L和30g/L硫酸溶液中的腐蚀性能进行比较研究。结果表明,在各种硫酸溶液中1#镍基涂层的腐蚀电流/腐蚀速率最大,3#钴基涂层的最小,2#镍基涂层的和3#钴基涂层接近。随着稀硫酸浓度的增加,激光熔覆的镍、钴基涂层的耐腐蚀性能有下降趋势。     

涂镀合金层的合金铸铁齿轮的接触疲劳强度研究

以齿轮为研究对象，用常用的辊子模拟方法，在Cu-Cr-P合金铸铁辊子试件表面分别涂镀Cu金属层、NiW合金层，然后与未涂镀的试件一起进行接触疲劳强度对比试验，共试验试件30对。试验结果表明：表面合金涂层能显著提高合金铸铁齿轮的接触疲劳寿命，文中同时分析了合金涂层的组织结构和性能。     

镍基高温合金K17的激光熔覆处理热裂纹敏感性研究

在铸造镍基高温合金涡轮叶片Ｋ１７上激光熔覆３种不同的钴基合金粉末，研究了３种组配的金相组织，显微硬度分布，成分分布及热裂纹敏感性。结果表明：激光熔覆钴基粉末对于Ｋ１７材料的叶冠端有改性作用，降低了Ｋ１７材料的热裂纹敏感性，涂层与基材能形成良好的冶金结合且涂层硬度较高。     

等离子喷涂—烧结含有氟化物共晶的镍,钴基自润滑涂层

本文叙述了采用等离子喷涂把含有镍、钴基自熔合金和氟化物共晶混合粉末沉积到耐热钢上,经还原气氛烧结,制备一种固体自润滑涂层。于滑动接触的磨损试验机上进行磨损试验表明,涂层组份明显地影响室温下涂层与钛合金之间的摩擦特性,喷涂粉末中CaF_2-BaF_2共晶含量在40～60wt.%(下同),摩擦系数在0.2～0.3之间,并且有较低的磨损率。电子扫描显微分析证实,烧结条件对涂层的结构有显著影响,经1100℃,15分钟烧结的镍、钴基自润滑涂层,结构致密,氟化物共晶分布均匀,改善了涂层的磨损特性和抗氧化特性。从七十年代初开始,固体自润滑涂层用于冶金和航空工业上,降低高温下金属及其合金之间的相对摩擦系数,提高合金加工工具和发动机部件的使用寿命。     

MATLAB在激光涂层零件可靠性建模中的应用

制备了自熔合金粉末激光熔覆涂层试件,在多次撞击疲劳试验机上进行了可靠性试验。借助MATLAB对样本数据进行分析,建立了激光涂层零件的多冲可靠性模型。分析得出激光涂层零件在多冲载荷下疲劳寿命服从对数正态分布,并拟合P-S—N曲线,建立了多冲应力与疲劳寿命以及可靠度之间的关系。在理论分析的基础上设计了可靠性建模界面,为进一步的可靠性分析提供基础。     

镍基合金表面激光熔覆钴基合金涂层的耐磨性能

为了提高涡轮叶尖端部的耐磨性能,以钴基合金粉末为涂层原材料,利用CO2激光器,在镍基合金表面上熔覆了优质耐磨涂层.采用销盘式摩擦磨损试验机进行了镍基合金及激光熔覆涂层的干摩擦磨损试验.试验结果表明,镍基合金的平均摩擦系数为0.48,钴基合金涂层的平均摩擦系数为0.30,钴基合金涂层的平均磨损量低于镍基合金材料,说明钴基合金涂层具有较高的耐磨性.     

盾构滚刀材料表面镍基碳化钨涂层摩擦学性能研究

目的 盾构滚刀磨损是盾构施工中最常见的问题之一,为减缓刀具的剧烈磨损、延长刀具的使用寿命,采用等离子堆焊工艺在盾构滚刀表面制备镍基碳化钨涂层以强化滚刀性能,基于盾构滚刀服役的真实工况,研究滚刀涂层的摩擦学性能及其合理的评价方式.方法 对镍基碳化钨涂层在往复滑动、冲滑复合(冲击+滑动)两种相对运动模式下进行摩擦磨损试验研究.结果 制备镍基碳化钨涂层后可提高滚刀的耐磨性.往复滑动磨损后,镍基碳化钨涂层的磨痕宽度为0.42 mm,而H13钢的磨痕宽度达到0.78 mm,镍基碳化钨涂层的抗冲滑性能也明显优于H13钢.两种相对运动模式下镍基碳化钨涂层均主要承受磨粒磨损,但往复滑动模式下涂层存在局部剥落,而冲滑复合模式下则伴随一定的粘着磨损.结论在两种相对运动模式下,镍基碳化钨涂层表面的高硬度碳化钨颗粒都可阻止磨粒对较软镍基合金区域的切削与碰撞.相较往复滑动模式,冲滑复合模式下镍基碳化钨涂层要承受冲击和滑动的耦合作用,涂层的磨痕特征以及损伤形式都有明显的不同.采用冲滑复合运动模式的摩擦磨损试验能对盾构滚刀刀圈的摩擦学性能进行更全面、合理的研究及评价.     

铬镍钨铌系铁基高温耐磨合金等离子弧堆焊

通过高温硬度 ，高温磨损试验，成功地研究了铁基Ｃｒ－Ｎｉ－Ｗ－Ｎｂ系高温耐磨料磨损等离子弧堆焊合金粉末，从而可替代价格昂贵的镍基和钴基等离子弧焊合金，同时系统地研究了合金元素高温耐磨性的影响规律及磨机理。     

国外激光熔覆材料、工艺和组织性能的研究

综述了国外激光熔覆材料、工艺参数和组织性能的研究 ,概括了铁基、镍基、钴基合金、不锈钢、钛、铝、铜、青铜合金、陶瓷以及复合材料等激光熔覆的发展     

Weldability and high temperature performance of welded joints of heat-resisting alloys

The applications of various heat resisting alloys applications depend upon the service temperature and the environment in which they are employed; austenitic stainless steels are employed mainly in the temperature region of approximately 850-950 K and Fe-base, Co-base and Ni-base superalloys are employed for high-temperature use at more than approximately 950 K. Problems concerning the integrity of weld procedures and high-temperature performance of weld zones should be considered for the application of these heat-resisting alloys to welded structures. In fact, most heat resisting alloys have poor weldability compared with carbon and low-alloy steels and are subject to problems such as cracking during welding. Furthermore, there are many instances of deteriorating high-temperature performance of the weld zone due to changes in the microstructure which accompany welding. On the other hand, heat-resisting alloys are employed in severe high-temperature environments and it is highly possible that there will be an occurrence of fissures and deterioration due to deformation, creep damage, oxidation and carburising. There are many cases where materials which have been in service for extended periods have increased weld crack susceptibility. Repair welding of these requires further attention to be given to the possibility of weld cracks.     

快淬非晶合金制备态磁各向异性研究SCIEI

本文详细研究了铁基、铁镍基和钴基非晶合金条带制备态的平面磁各问异性。测定了退火前后试样中各向异性的变化及各向异性常数K_(us)随温度的变化,得出K_(us)(T)∝M_s^2(T)关系,由此得出平面磁各向异性由应力各向异性和表面形状各向异性两部分组成。     

激光熔覆工艺特性及裂纹敏感性研究

通过对Ni基和Co基合金在45钢、2Cr13钢基材上的激光熔覆工艺的定量研究,运用正交试验法确定了影响熔覆层裂纹形成的主要因素,并提出 控制和消除熔覆层裂纹的工艺方法。     

Corrosion and Erosion-Corrosion Processes of Metal-Matrix Composites in Slurry Conditions

The corrosion and erosion-corrosion (EC) processes of four metal-matrix composites (MMCs) in a simulated cooling water environment have been assessed in this article. The MMCs consisted of two Ni-base and two Fe-base matrices alloyed with different concentrations of chromium, molybdenum, boron, silicon, and carbon; the matrices were reinforced with tungsten carbide (WC) particles. The corrosion behavior has been investigated using a combination of potentiostatic polarization and post-tests surface analysis. The EC processes were studied by in situ electrochemical techniques measuring the current density and corrosion potential response at different slurry temperatures and sand content. At static conditions it was found that as the temperature increased, there was a transition from a homogeneous corrosion of the matrix to an interfacial corrosion mechanism. The Ni-base MMCs showed a better corrosion resistance and interestingly a highly alloyed matrix did not significantly improved MMC’s corrosion resistance. In the in situ EC tests, the Fe-base MMCs showed a constant increase in the current density at all sand contents. Whereas, significant changes were not observed in the Ni-base MMCs below 0.5 g/L. Although sand content had an effect on the monitored current density (the current increased as the sand content increased) this effect was less pronounced above 3 g/L.     

Interdiffusion in the Face-Centered Cubic Phase of the Co-Al-W-Ta System Between 1090 and 1240 °C

Interdiffusion of Al, W, Ta and Co in a Co-base alloy at temperatures between 1090 and 1240 °C has been investigated. The interdiffusion coefficients were found to be close to those reported for these elements in Ni-base alloys. Combining the diffusion simulation software DICTRA with the Ni-base diffusion databases TCNi₅ and MobNi₃, the interdiffusion profiles of Co, Al W, and Ta were modeled for Co9Al8W2Ta/Co diffusion couples annealed at different temperatures and for different times. The results show that interdiffusion in the Co-Al-W-Ta alloys can be modeled reasonably well using the available commercial databases for thermodynamics and kinetics of Ni-base systems.     

Burner rig trials with nickel- and cobalt-base alloys

Selected Ni- and Co-base alloys were hot corroded in a burner rig facility at temperatures cycled from ambient to 870 or 980°C respectively for times in excess of 3000h. A diesel fuel maintained at lw/oS and doped with sea salt to 476 ppm produced characteristic hot corrosion attack at 870°C and more classical oxidation attack at 980°C. This preliminary investigation shows that the products formed on the Ni-base alloys at 980°C were cracked and dominated by local surface protrusions (“warts”). Co-base alloys did not show these features nor were they observed following tests at the lower temperature. A small % of Y in a simple Nimonic alloy reduced the extent of scale damage but did not eliminate hot-corrosion/oxidation attack.     

HIGH TEMPERATURE FATIGUE BEHAVIOUR OF A DIRECTIONALLY SOLIDIFIED COBALT-BASE SUPERALLOY

1.IntroductionCo-basesuperalloysareextellsivelyusedasvallesandotherhightemperaturestructuralcomponentsinaircraftalldindustrialturbinesbecauseoftheirexcellelltstress-rupturepropertiesandhotcorrosionresistance.Theimprovementinthehightemperaturemechanicalperformanceofthesealloyshasevolvedoveralongperiodfromtheconvelltionalcastsuperalloysuptothemoderndirectionallysolidifiedalloys.Recently,adirectionallysolidifiedCo--basesuperalloywasdeveloped,whichisamodificationofX40alloyillTa,Ti,Zr,Mo,AlandB.…     

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 本文通过对35SiMnMoV复相钢的常温疲劳试验研究和GH4049镍基高温合金的高温疲劳试验研究,获得了大量的试验数据和得出了相应的裂纹扩展行为规律。结合中外文献对疲劳短裂纹的研究结果,在试验结论和理论知识的基础上,根据疲劳短裂纹扩展速率与微观参量之间的关系,并初步探索建立了用微观参量来表达的短裂纹扩展速率表达式的模型