提出了酸分解铅锌矿试样,氟硅酸钾滴定法测定试样中二氧化硅的方法。铅锌矿样品依次用硝酸、盐酸消解后,在加入氢氟酸的情况下,二氧化硅与氢氟酸反应形成氟硅酸,并在硝酸介质中与过量硝酸钾反应生成氟硅酸钾沉淀, 经过滤、洗涤后溶于沸水中,以硝氮黄为指示剂,采用氢氧化钠标准溶液滴定水解后生成的氢氟酸,从而间接测定了铅锌矿中二氧化硅的含量。实验表明:以 10mL硝酸为沉淀介质,3.0g硝酸钾为沉淀剂,沉淀放置20min后过滤沉淀并用50g/L硝酸钾-50%乙醇溶液洗涤沉淀,可有效消除铅锌矿中大量铅的干扰;选择硝氮黄为指示剂,滴定终点颜色突变更明显。方法应用于铅锌矿标准样品中二氧化硅的测定,结果与认定值相符;应用于铅锌矿实际样品测定,结果的相对标准偏差(RSD,n=12)分别为0.5%和1.3%。与传统的重量法进行对比试验,结果一致。方法适用于测定铅锌矿中质量分数为8%~67%的二氧化硅。

关键词：氟硅酸钾；滴定法；铅锌矿；二氧化硅

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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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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 influence of yttrium on the corrosion resistance of four valve steels (X33CrNiMn23-8, X50CrMnNiNbN21-9, X53CrMnNiN20-8 and X55CrMnNiN20-8) in combustion gases of fuel oil containing 10 wt. % of biocomponents has been studied at 1173K under thermal shock conditions. These experiments have been carried out by rapid heating of the studied materials up to 1173K and after two hours cooling down to room temperature. These thermal shocks have been repeated hundreds of times, determining after every shock the mass changes of the corroded samples. It has been found that small amount of yttrium deposited on the steel surface using electrochemical treatment considerably improves the scale adherence and consequently corrosion resistance in the case of X33CrNiMn23-8 steel, containing the highest chromium concentration.

关键词：阀门钢；腐蚀；燃烧气体；;热冲击；钇效果

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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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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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This paper is a review of results for Ti-Mn [1], Ti-Mn-Al [2] and Ti-Mn-Fe [3] alloys that have been previously published. Titanium alloys, especially beta-type titanium alloys, have high specific strength, excellent corrosion resistance and good biocompatibility. Unfortunately, applications of titanium alloys are limited by their relatively higher cost. One reason is the use of rare and expensive metallic elements, such as vanadium and molybdenum, as a beta stabilizer. In order to reduce the cost, inexpensive and abundantly available metallic elements should be used as beta stabilizers. Manganese was adopted as a beta stabilizer because it is an abundant metallic element in the Earth's crust and is relatively low in cost. The heat treatment behavior of Ti-Mn, Ti-Mn-Al and Ti-Mn-Fe alloys was investigated through electrical resistivity and Vickers hardness measurements, X-ray diffraction measurements to identify phase constitution, and observations using a light microscope [1], [2] and [3].

关键词：低成本；公测型合金；锰；无热欧米茄

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The Auger export pipelines are connected to the TLP by steel catenary risers (SCRs). This is believed to be the first time steel pipe has been used for catenary risers. SCRs offer advantages over tensioned risers, since SCRs need no heave compensation and no subsea connections, and over risers made of "flexible pipe", since SCRs are much less expensive. However, significant design effort was required to prove that the SCRs could safely withstand environmental loads and the effects of TLP motions. The design effort consisted of extensive dynamic analyses as well as full scale fatigue testing of both the riser joint welds and the flexible joint that connects the riser to the TLP pontoon. Devices which suppress vortex induced vibrations were also tested. SCR installation is accomplished by lowering the riser on the abandonment and recovery cable from the J-Lay installation vessel and transferring the riser on a chain that is run through a chain jack hung from the TLP upper deck structure. A special Installation and Maintenance System was built for this purpose.

关键词：出口管道；立管接头焊缝；钢铁

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