DZ9000E型移动式超音速火焰喷涂系统的研制

与氧煤油超音速火焰喷涂系统相比,DZ9000E型氧燃气超音速火焰喷涂系统的开发更侧重于降低涂层的成本以及适应不同工况中现场使用的可移动性.DZ9000E型手持式喷涂枪上配有双气阀手柄、送粉开关及压缩/冷却气阀,为用户提供轻便、简捷的操作模式.整机价格便宜及运行成本低使这一系统更适应国内中小客户喷涂中低价位HVOF涂层的需求.采用DZ9000E系统喷涂WC-12Co涂层具有良好的涂层性能,平均显微硬度可达1 000 HV0.2左右,涂层与基体间的结合强度超过53 MPa.     

Synthesis and oxidation behavior of nanocrystalline MCrAlY bond coatings

Thermal barrier coating systems protect turbine blades against high-temperature corrosion and oxidation. They consist of a metal bond coat (MCrAlY, M = Ni, Co) and a ceramic top layer (ZrO₂/Y₂O₃). In this work, the oxidation behavior of conventional and nanostructured high-velocity oxyfuel (HVOF) NiCrAlY coatings has been compared. Commercially available NiCrAlY powder was mechanically cryomilled and HVOF sprayed on a nickel alloy foil to form a nanocrystalline coating. Freestanding bodies of conventional and nanostructured HVOF NiCrAlY coatings were oxidized at 1000 °C for different time periods to form the thermally grown oxide layer. The experiments show an improvement in oxidation resistance in the nanostructured coating when compared with that of the conventional one. The observed behavior is a result of the formation of a continuous Al₂O₃ layer on the surface of the nanostructured HVOF NiCrAlY coating. This layer protects the coating from further oxidation and avoids the formation of mixed oxide protrusions present in the conventional coating. The original version of this article was published as part of the ASM Proceedings, Thermal Spray 2003: Advancing the Science and Applying the Technology, International Thermal Spray Conference (Orlando, FL), May 5–8 2003, Basil R. Marple and Christian Moreau, Ed., ASM International, 2003.     

超音速火焰喷涂层电解抛光研究

超音速火焰喷涂WC-Co涂层能大幅度提高零件的耐磨性能,但涂层的高硬度使得后续的抛光工作极其困难,使其应用受到限制.探讨了采用电解工艺对喷涂层进行抛光的可行性,包括电解液配方的研制,加工参数的优选等.结果表明,采用电解工艺进行WC-Co喷涂层抛光不仅可行,而且效率高,质量好.选用合适的参数能将喷涂层表面粗糙度从4.0 μm迅速降至0.7 μm左右.     

高速燃气电弧喷涂的涂层过渡特性

高速燃气电弧（HVAF-ARC）喷涂是20世纪90年代末期兴起的一种电弧喷涂技术，可用于电站锅炉“四管”表面防腐防磨工程。为此，对HVAF-ARC喷涂技术进行工艺性能研究，并分别对FeNiCr-WC和FeNiCr-Cr2G涂层过渡特性进行了比较。由于超音速活性电弧气氛对丝材有良好的雾化效果，因此两种涂层材料与基材的结合都很好，在扫描电镜观察下，均未发现有连续间隙存在。对涂层试样进行结合强度试验，结果是FeNiCr-WC涂层的结合强度比FeNiCr-Cr2C3涂层要高10％左右。最后，对两种涂层的X射线衍射结果进行了分析，发现FeNiCr-Cr2G3丝材组分Cr2C3在活性电弧气氛中会加速分解，而FeNiCr-WC丝材组分WC的分解则不明显。结论是FeNiCr-WC涂层的过渡性能优于FeNiCr-Cr2G3涂层。     

Mg0.5La0.5MnxAl12-xO19的甲烷纯氧燃烧催化行为研究

采用溶胶凝胶法,以柠檬酸为络合剂,合成了Mg0.5La0.5MnxAl12-xO19(x=0,1,2,3)系列六铝酸盐催化剂,用XRD对样品结构进行了分析,考察Mn的掺量对样品相结构的影响;采用固定床反应器,考察了在纯氧条件下催化剂的甲烷催化燃烧的活性.实验结果表明:采用溶胶凝胶法制备的Mn离子掺杂样品均能形成六铝酸盐相;在550℃,Mn离子能显著提高六铝酸盐的甲烷纯氧燃烧催化能力.     

高速电弧喷涂 FeCrNi / Ni 包覆金刚石复合涂层的摩擦学特性研究

目的研究高速电弧喷涂FeCrNi/Ni包覆金刚石复合涂层的组织结构和摩擦学特性。方法采用高速电弧喷涂技术在45#钢基体上制备FeCrNi/Ni包覆金刚石复合涂层,并对其进行滑动摩擦磨损研究,利用SEM,EDS对涂层的形貌、组织成分进行分析,测定涂层的显微硬度、孔隙率等。结果 FeCrNi/Ni包覆金刚石复合涂层组织致密,孔隙率较低,呈现典型的层状结构。涂层的摩擦系数随着磨损时间的增加而先增大,再趋于平稳。结论由于涂层中加入了金刚石硬质相,涂层具有较高的显微硬度和优异的耐摩擦磨损性能。     

Microstructure,adhesion, and tribological properties of conventional plasma-sprayed coatings on steel substrate

A variety of metallic and oxide coatings were deposited under various conditions on 1020 mild steel substrate by conventional plasma spraying. The coating thickness, microhardness, cohesion and adhesion failure loads, friction coefficient, and abrasive wear resistance were evaluated. The coatings were classified as follows, in order of decreasing microhardness and wear resistance: alumina, chromia, 316 stainless steel, Ni-5% Al, elemental aluminum and aluminum-polyester. Wear resistance increased with increasing microhardness and decreasing friction coefficient. The microhardness and wear resistance of high-velocity oxy-fuel (HVOF) diamond jet (DJ)-sprayed aluminum were found to be superior to those of plasma-sprayed aluminum. Plasma or flame-sprayed metallic coatings adhered well to the substrate. The cohesion, adhesion, microhardness, and wear resistance of alumina coatings exceeded those of equally thick chromia coatings.     

生物乙醇柴油的特性及其在柴油发动机上的应用

含氧燃料乙醇和生物柴油都是重要的生物质燃料,它们与柴油掺混使用可以降低柴油发动机尾气的污染物排放,特别是颗粒物的排放。在分别对乙醇柴油(乙醇和柴油的混合燃料)和生物柴油作为柴油替代燃料的研究进行总结的基础上,介绍了一种新的柴油混和燃料——生物乙醇柴油,即生物柴油-乙醇-柴油三组分混合燃料。综述了有关生物柴油-乙醇-柴油三组分物系的混溶特性和相行为,以及生物乙醇柴油在柴油发动机上应用时的燃料性质及其排放特性的最新研究结果。     

Microstructures and adiabatic shear bands formed by ballistic impact in steels and tungsten alloy

Projectiles of sintered tungsten alloy were fired directly at two kinds of steel target plates. The microstructures near the perforation of a medium, 0.45% carbon steel target plate can be identified along the radial direction as: melted and rapidly solidified layer, recrystallized fine‐grained layer, deformed fine‐grained layer, deformed layer and normal matrix. The adiabatic shear bands cannot be found in this intermediate strength steel. The microstructures along the radial direction of perforation of 30CrMnMo steel target plate are different from that of the medium carbon steel. There was a melted and rapidly solidified layer on the surface of the perforation, underneath there was a diffusing layer, and then fine‐grained layer appeared as streamlines. Several kinds of adiabatic shear bands were found in this higher strength steel; they had different directions and widths, which were relative to the shock waves, as well as the complex deformation process of penetration. The deformation of the projectiles was rather different when they impacted on target plates of medium carbon steel and 30CrMnMo steel. The projectile that impacted on the medium carbon steel target plate was tamped and its energy dissipated slowly, while that which impacted on the 30CrMnMo steel target plate was sheared and the energy dissipated quickly.     

走滑-伸展应力区高速异常带特征、成因及定量刻画——以渤海湾盆地莱北低凸起明下段为例

伸展应力和走滑剪切应力共同控制莱北低凸起的形成和演化,在钻探过程中发现该区横向速度变化较大,严重影响了钻前深度预测和后续滚动勘探。为此,利用测井资料、三维地震资料和地震速度资料研究了莱北低凸起走滑-伸展应力区的高速异常现象。基于区域应力场机制及压实量分析,讨论了构造对地层速度的横向控制作用,探索了高速异常的成因,利用"去除正常压实作用"的方法定量刻画了高速异常带。结果表明:①在走滑-伸展应力区,受次级挤压分量产生的水平挤压作用影响,雁列式T破裂带内部地层除了存在垂向正常压实作用之外,还存在水平构造压实作用——莱北低凸起浅层NE向高速异常带的成因;②高速异常带沿着雁列式T破裂展布,其分布范围受断裂活动范围控制,高速异常量与断层的活动强度具有较强的正相关性,与高速异常带的发育规律吻合。