Wear and oxidation resistance of combustion CVD grown alumina films

Alumina thin films were synthesized on Si (100) and Ni–20Cr substrates using combustion chemical vapor deposition. Aluminum acetylacetonate (0.005 M) dissolved in ethanol was used as the precursor solution. The films deposited at 900 and 1000 °C are found to be θ-alumina and those deposited at 1100 °C to be α-alumina. The scanning electron micrographs showed the films to be made up of crystallites of two different sizes and shapes. The coefficient of friction, of alumina coated Si samples, measured using a tribometer showed high value (~ 0.7) at initial passes and subsequently saturated to low value (~ 0.5) at higher sliding distances. It was observed that the tribological properties, of the films, are not affected significantly by the crystal structure and crystallite size. Oxidation resistance of alumina-coated Ni–20Cr specimens were studied using a thermo-gravimetric analyzer by exposing them to isothermal heating at 1000 °C in 20% O₂–Ar gas mixture. The results indicated that the coated specimens are 18 times more oxidation resistant, at initial stages, compared to uncoated specimens. The resistance slowly dropped to six times, where it reached a saturation value.     

The role of Si interstitials in the migration and growth of Ge nanocrystallites under thermal annealing in an oxidizing ambient

We report a unique growth and migration behavior of Ge nanocrystallites mediated by the presence of Si interstitials under thermal annealing at 900°C within an H₂O ambient. The Ge nanocrystallites were previously generated by the selective oxidation of SiGe nanopillars and appeared to be very sensitive to the presence of Si interstitials that come either from adjacent Si₃N₄ layers or from within the oxidized nanopillars. A cooperative mechanism is proposed, wherein the Si interstitials aid in both the migration and coarsening of these Ge nanocrystallites through Ostwald ripening, while the Ge nanocrystallites, in turn, appear to enhance the generation of Si interstitials through catalytic decomposition of the Si-bearing layers.     

Friction and Wear Phenomena of Vegetable Oil–Based Lubricants with Additives at Severe Sliding Wear Conditions

The tribological responses of palm oil and soybean oil, combined with two commercial antiwear additives (zinc dialkyl dithiophosphate and boron compound), were investigated at a lubricant temperature of 100°C and under severe contact conditions in a reciprocating sliding contact. The friction coefficient of palm oil with zinc dialkyl dithiophosphate was closest to the commercial mineral engine oil, with a 2% difference. The soybean oil with zinc dialkyl dithiophosphate produced a 57% improvement in wear resistance compared to its pure oil state. The existence of boron nitride in vegetable oils was only responsive in reduction of wear rather than friction. The response of commercial antiwear additives with vegetable oils showed a potential for the future improvement in the performance of vegetable oils.     

Biocomposites based on poly(lactic acid) and seaweed wastes from agar extraction: Evaluation of physicochemical properties

Seaweed waste (SWW) is a residue or by‐product from the filtration step of the agar extraction process, and it has been explored as an inexpensive and effective filler for incorporation by melt blending into a poly(lactic acid) (PLA) matrix. PLA‐SWW biocomposites were manufactured with various contents of SWW (0, 5, 10, 15, and 20 wt %) using a sheet extrusion process. PLA was functionalized with maleic anhydride (MAH) by reactive extrusion using dicumyl peroxide (DCP) as an initiator, and it was extruded using 0, 5, and 20 wt %. SWW content. The mechanical, thermal, structural, and morphological properties of the processed biocomposites were investigated. Regarding the mechanical behavior, a slight increase in the tensile modulus was observed at low SWW content. The thermal properties indicated that the rigid amorphous phase content was enhanced in the biocomposites. This work suggests that SWW can be used as filler to develop environmental friendly biocomposites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42320.     

Immobilization of TiO2 into Self‐Supporting Photocatalytic Foam: Influence of Calcination Temperature

Immobilization of photocatalytic powder is crucial to obtain industrially relevant purification processes. To achieve this goal, self‐supporting TiO₂ foams were manufactured by a polyacrylamide gel process. These gels were calcined at different temperatures to study the effect of the calcination temperature on foam characteristics (rigidity, crystallinity, and porosity) and its influence on photocatalytic activity. The results show that an optimal degradation is achieved for those foams calcined between 700 and 800°C. Calcination at higher temperatures results in a steep decrease in activity, explained by stability issues of the material due to formation of Na₂SO₄ phases and a larger rutile fraction.     

矿化剂硫酸钙和氟化钙作用下硅酸三钙的合成(英文)

硅酸三钙(C3S)是硅酸盐水泥和阿利特硫铝酸盐水泥熟料中重要的矿物之一。为研究C3S的特性和性能,使用CaSO4和CaF2作为矿化剂,分别在1 350、1 400和1 450℃合成了高纯度的C3S。1 350℃得到的C3S纯度高于95%,而在1 400和1 450℃合成的C3S纯度高于97%。检测结果显示3个不同温度下合成的C3S的游离氧化钙含量均小于1%。样品的化学成分分析表明,1 400和1 450℃合成的C3S中仅有痕量的SO3存在,合成过程中几乎所有的CaSO4均分解为CaO,并且与部分SiO2形成了C3S。对所有样品的X射线衍射分析结果显示,合成的C3S为M1与(或)M3型。扫描电子显微镜分析结果显示,不同温度下合成的C3S的微结构有所不同。通过差热分析对矿化剂作用下的C3S合成过程进行了分析,结果表明该合成方法与通常的C2S和CaO通过固相反应合成C3S之间存在显著差异,是一个两步合成过程。     

Sustainability: real and/or virtual?

The starting point for this paper is the identification of the four necessary and sufficient conditions which a building should exhibit to be judged to be sustainable; fitness-for-purpose, cost effectiveness, environmental friendliness, and cultural significance. The contribution which the current generation of CAD tools is making to the complex human activity of designing sustainable buildings is then discussed under the headings of widening the search for solutions, integrating the decision-making process, improving design insights, differentiating objective/subjective issues and photorealistic visualization. The paper then describes developments in the next generation of IT tools, based on virtual reality, which will allow multiple designers, working in distributed locations and on different computer platforms, to design from within the virtual world.     

五富兰克林大楼

该大楼有20层,包含55个公寓,在楼中可以眺望啥德逊河、东河和曼哈顿的天际线。 该大楼有一个戏剧性、极富装饰性的立面,灵感来自Tribeca的19世纪的铸铁建筑和当代时尚。闪闪发光的黑色金属横带将包装的墙面扭曲,划分了阳台、平台和遮阳篷的位置,同时体现了立面的框架感。