Ferritic stainless steels are promising candidates for IT-SOFC interconnect applications due to their low cost and resistance to oxidation at SOFC operating temperatures. However, steel candidates face several challenges, including long term oxidation under interconnect exposure conditions, which can lead to increased electrical resistance, surface instability, and poisoning of cathodes due to volatilization of Cr. To potentially extend interconnect lifetime and improve performance, a variety of surface treatments were performed on AISI 441 ferritic stainless steel coupons prior to application of a protective spinel coating. The coated coupons were then subjected to oxidation testing at 800 and 850 degrees C in air, and electrical testing at 800 deg C in air. While all of the surface-treatments resulted in improved surface stability (i.e., increased spallation resistance) compared to untreated AISI 441, the greatest degree of improvement (through 20,000 hours of testing at 800 deg C and 14,000 hours of testing at 850 deg C) was achieved by surface blasting.

关键词：合金；尖晶石；不锈钢；表面处理；涂料

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The research under this project focused on a theoretical and computational modeling of dislocation dynamics of mesoscale deformation of metal single crystals. Specifically, the work aimed to implement a continuum statistical theory of dislocations to understand strain hardening and cell structure formation under monotonic loading. These aspects of crystal deformation are manifestations of the evolution of the underlying dislocation system under mechanical loading. The project had three research tasks: 1) Investigating the statistical characteristics of dislocation systems in deformed crystals. 2) Formulating kinetic equations of dislocations and coupling these kinetics equations and crystal mechanics. 3) Computational solution of coupled crystal mechanics and dislocation kinetics.

关键词：金属；统计力学；耦合；晶体；变形

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Although steel orthotropic deck is currently the most widely adopted solution for long-span bridges, the poor adhesion to the upper asphalt layers still represents a serious problem without a clear solution. In recent decades many techniques that involve the use of special bituminous bonding coats, reinforced asphalt membranes, net-reinforced steel deck surfaces, or epoxy asphalt binders have been applied, with varying results, to improve the level of adhesion of the asphalt pavement to the steel surface. In this experimental study, two such techniques were adopted to investigate the shear resistance of steel-asphalt pavement systems. The first technique used epoxy asphalt both as a bonding coat and as a binder of the upper asphalt layer, while the second technique involved the use of a reinforced asphalt membrane that was applied on the steel deck before overlaying with conventional hot-mix asphalt (HMA). The Ancona Shear Testing Research and Analysis shear test device was used to evaluate the shear resistance of different types of HMA-steel interfaces and to investigate the effects of temperature and normal stress. The results have been compared with the shear properties of bitumen-coated interfaces, studied in previous research. The results showed that epoxy asphalt guaranteed high performance regardless of the test temperature. However, the shear resistance of the system with the asphalt membrane was lower than with the epoxy asphalt, although it was higher than the resistance of bitumen-coated interfaces at high temperatures.

关键词：正交异性钢桥；钢铁；沥青膜

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Improved software interoperability is key to realizing more fully the potential benefits of integrated and accelerated project delivery in a way that also somehow ensures product quality. The increasing appeal of three-dimensional (3-D) building information modeling (BIM) notions applied to bridges [known as bridge information modeling (BrIM)] motivates the need for principled prescriptions of associated electronic data exchanges between various project stakeholders and the various software applications that they use. Such data exchanges must be sufficiently precise to facilitate detailing for fabrication and construction while being sufficiently concise to facilitate parametric modeling and thereby avoid needless data duplication. The highway geometry to which bridges must conform distinguishes BrIM from the building column grid orientation of BIM at the outset of the bridge life cycle. In contrast to the overdefined highway geometry in the LandXML data exchange standard, a 3-D control curve is defined, presented, illustrated, and recommended as the basis for parametric data exchange suitable through the life cycle of steel Ⅰ-girder bridges on (straight and) curved alignments. This 3-D control curve combines in a single curve the traditional horizontal control line and profile grade line that bridge structural engineers receive from highway designers to define bridge geometry. Data exchanges associated with three distinct stages in the life cycle of a steel bridge are defined and illustrated: analysis and design, detailing for fabrication, and erection and construction. The data exchange based on a 3-D control curve provides the data integrity required through the life cycle of a steel bridge.

关键词：三维参数；钢铁；曲线钢桥

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For the reduction or complete compensation of grease and lubricants in mechanical engineering, special combined coatings for machine components with extended tribological and chemical properties have been developed. Ceramic or metal polymer coating systems are a combination of thermally sprayed hard materials with polymers containing solid lubricants of inorganic and fluorpolymeric origin (i.e. lubricant lacquers). The thermally sprayed hard material guarantees hardness and wear resistance and the lubricant lacquer causes low friction coefficients and smooth gliding performance. In this paper, results of different polymer and multicoating systems on steel substrates are presented. Molybdenum, a cermet based on tungsten carbide, a copper based alloy and chromia were used as wear resistant materials and deposited by means of High Velocity Flame Spraying (HVOF/HVLF). On these surfaces, lubricant lacquers of some μm thickness were deposited by air spraying. The life-time and the friction coefficient of the resulting layers depending on surface texture of the hard material or substrate and lacquer composition were determined using a twin disc tester under dry sliding conditions.

关键词：油脂；钢铁；固体润滑剂；摩擦系数

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The French five-point bending (5PB) test provides a laboratory-scale test that allows studying the fatigue resistance of surfacing systems on orthotropic steel deck (OSD) bridges. The surfacing structure for OSD bridges in the Netherlands is mostly a multilayer system: top porous asphalt (PA) layer, guss asphalt (GA) layer, steel deck, and two membrane layers. In this paper, an analytical solution for the 5PB test setup is presented first. To understand better the influence of geometrical, mechanical, and structural parameters on the performance of the typical multilayer surfacing system of OSD bridges in the Netherlands, the 5PB test specimens with five structural layers have been investigated. The parametric study was performed at the numerical platform CAPA-3D, which was developed at the Section of Structural Mechanics of the Delft University of Technology. The thicknesses of the top PA layer, middle GA layer, and the steel plate were varied. The influences of the mechanical properties of both top and bottom membrane layers were studied. The sensitivities of those influence factors were evaluated by examination of the maximum tensile stress at the top surface of the PA layers and the strain distributions through the entire thickness of the specimen at two cross sections.

关键词：五点弯曲；钢铁；抗疲劳性

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Fine balance between active galvanic and passive barrier corrosion protection by zinc-rich hybrid paints is explored depending on the absolute and relative amounts of the electrically semi-conducting particles, viz. polypyrrole (PPy) modified alumina hydrate and multi-walled carbon nanotubes (MWCNTs) and the zinc pigments. The former was varied between 3.21 and 1.75 wt.%, the latter was altered from 70 to 80 wt.% in the primers. The coating with less zinc indicated firm and stable barrier nature in a 254 h immersion test whereas the primer with greater zinc content afforded superior galvanic corrosion prevention in salt-mist test over 142 days. Different nature of the coatings are expounded on the basis of structure and 3D arrangement of the nano-size inhibitor particles in the epoxy vehicle besides interpreted considering varied grain contents caused changing electrical percolation and electrolytic conductivity of the primers.

关键词：聚吡咯修饰碳纳米管；低碳钢；富锌涂料混合

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Fluidized bed reactor chemical vapor deposition (FBR-CVD) has been used to enrich the surface of oxygen free high conductivity (OFHC) copper with titanium, silicon and aluminum. This technique enables the production of coherent and adherent intermetallic surface layers of uniform thickness and high hardness. The characterization of the coatings was performed using backscatter scanning electron microscopy (BS-SEM), X-ray diffraction (XRD), glow discharge optical emission spectroscopy (GDOES) and micro-hardness. The tribological properties of the coatings in dry sliding contact with steel were evaluated by pin-on-disc wear testing.

关键词：铜；磨损；摩擦系数；钢铁

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This paper aimed to investigate the effect of shape factor, slurry layers and pouring temperature in precision investment casting. Three controllable factors of the precision investment casting process (namely: shape factor, slurry layers (mold thickness) and pouring temperature) were studied at three levels each by Taguchi's parametric approach and single-response optimization was conducted to identify the main factors controlling surface hardness, dimensional accuracy (Ad) and surface roughness (Ra). Castings were produced using aluminum (Al), mild steel (M.S.) and stainless steel (S.S) at recommended parameters through ceramic shell precision investment casting process. The micro structure analysis has been used to study the surface morphology. Analysis shows that for surface hardness, contribution of shape factor, slurry layers and pouring temperature is 0.07%, 0.70% and 99% respectively. As regards to surface roughness, contribution of shape factor, slurry layers and pouring temperature is 1.14%, 16.80% and 81.90% respectively. Further for Ad contribution of shape factor, slurry layers and pouring temperature is 1.53%, 22.47% and 72.88% respectively. Confirmation experiments were conducted at an optimal condition showed that the surface hardness, Ad and Ra of the precision investment casting were improved significantly.

关键词：形状因子；浆层；浇注温度；钢铁

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The discovery in the 1980's of local brittle zones (LBZ's) in and near the heat-affected zone (HAZ) of the fabrication welds in certain offshore platform steels caused great concern among the engineers and welding specialists of the period and led directly to the preparation and adoption of API RP2Z in May 1987 of Recommended Practice for Preproduction Qualification for Steel Plates for Offshore Structures. This recommended practice describes a procedure by which steel producers could prequalify their product in advance of purchase and delivery and thereby reduce the risk of steel plate being delivered to the jobsite which would exhibit weldability problems from the standpoint of low HAZ toughness or HAZ cracking problems when using typical and conventional welding procedures, i.e., the need for extensive fracture toughness testing by the fabricator on each weld procedure was eliminated in favor of a more sophisticated one-time test program in the laboratory of the producer. This recommended practice covers two areas: (1) testing weld HAZ for toughness using CTOD tests and (2) delayed cracking tests using the controlled thermal severity test (CTS) and Y-groove test. This RP was developed for use with API steel specifications 2H, 2Y, and 2W. Most of the effort has been toward the quantification of API 2Y and 2W steels in thicker sections s4" (100 mm). This program has been scientifically successful albeit with a significant penalty of time and cost to the steel producer. There has been sufficient standardization that various purchasers have and will accept the same qualification performed previously for another job. This, of course, is exactly what API standards are intended to accomplish. API RP2Z was revised in 1992 and is currently being reviewed for a second revision intended to reduce some of the conservatism built into the original document by our lack of full understanding of the embrittling mechanisms in the HAZ of welded structural steels but now strongly supported by a substantial data base of good material. The paper discusses some of the proposed changes and contains data on the currently achievable fracture toughness levels.

关键词：海洋平台；钢铁；断裂韧性

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