Microstructural and tribological behavior of TiAlN/MoS2-Ti coatings

1. Introduction The search for a better wear resistant coating has resulted in the development of a class of hard, solid-lubricated coatings. The driving force behind the coating industry was the need to develop a proc-ess that will extend the life of steel machine parts, cutting tools, molding dies, and sliding parts. For example, in the stamping industry, severe abrasive wear and galling (cold metal welding) are expected. There is the need for an efficient application of lu-bricants both for…     

A Novel High-Speed Multiplexing IC Based on Resonant Tunneling Diodes

A new multiplexing IC based on the resonant tunneling diode (RTD) is proposed. The unique negative differential resistance characteristics arising from quantum effects of the RTD enable us to develop a new functional low-power digital circuit. The proposed multiplexing IC consists of two current-mode-logic monostable-bistable transition logic elements (CML-MOBILEs) based on the RTD and a low-power selector circuit block. The proposed circuit has been fabricated by using an InP RTD/ heterojunction bipolar transistor monolithic microwave integrated circuit technology. The multiplexing operation of the fabricated quantum effect IC has been confirmed up to 45 Gb/s for the first time as a monolithic technology based on the quantum effect devices. The dc power consumption is only 23 mW, which is found to be one-fourth of the current state-of-the-art conventional transistor-based multiplexing IC.     

MoS2／Ti复合膜的制备和性能

为了克服MoS2薄膜在大气环境下极易氧化失效且耐磨性能差的缺点，采用非平衡直流磁控溅射技术制备了MoS2／Ti复合膜，研究了Ti靶电流对复合膜结构和性能的影响。电子探针（EPMA）测定表明，膜中Ti的含量随着Ti靶电流的增加而增加。场发射扫描电子显微镜（FE．SEM）对膜的表面和截面形貌观察发现，膜的表面由尺寸为几十～几百纳米的颗粒组成，而膜的截面呈柱状晶结构。膜的致密性和Ti靶电流有关，电流越高，膜的致密性越好，从而膜的硬度也越高。     

Solvent fractionation of renewable woody feedstocks: Organosolv generation of biorefinery process streams for the production of biobased chemicals

A new organosolv biomass fractionation process (Clean Fractionation, CF) for the separation of lignocellulosic raw material into cellulose, hemicellulose and lignin has been developed. The lignocellulosic material is separated with a ternary mixture of methyl isobutyl ketone, ethanol and water in the presence of an acid promoter, which selectively dissolves lignin and hemicellulose, leaving cellulose as an undissolved solid. The resulting single phase liquor is treated with water giving an organic phase containing lignin and an aqueous phase containing hemicellulose. For woody feedstocks, the yield of the cellulose fraction across all separations averaged 47.7 wt% (±1.1). Representative separations gave cellulose fractions with average Klason lignin contents of 2.0% at acid concentrations of 0.1 M H₂SO₄ or greater. Little or no galactose, mannose or arabinose is observed in the cellulose, and at an acid concentration of 0.2 M, average xylose contents as low as 0.22% were observed. Average glucan contents for representative cellulose samples of 92.7% were observed, and rose as high as 98.2% for separations using 0.2 M H₂SO₄. Glucan contents as high as 97% were also observed if the cellulose was bleached using either a QPD or QPDE sequence. The average yield of the lignin fraction was 18.3 wt%. Representative lignin samples gave an average Klason lignin value of 91% with selected lignin samples exhibiting residual sugar levels of <0.5%. The aqueous hemicellulose fraction contains a higher level of non-sugar components, but can be purified by ion exchange chromatography.     

沉积参数对磁控溅射CrN_x膜结构和性能的影响

本文采用非平衡直流磁控溅射方法制备CrN_x薄膜,研究沉积参数对膜结构和性能的影响。结果表明沉积过程中增加N_2的分压,薄膜的组成由Cr_2N相转变成CrN相,膜的表面形貌也由胞状转化为正四面体。增加样品台的负偏压,沉积膜层更加致密,表面更加平坦。     

Assessment of the crack growth characteristics at the low corrosion fatigue limit of an A106 Gr b steel pipe weld

In the area of heavy construction, welding processes are vital in the production and maintenance of pipelines and power plants. The fusion welding process generates formidable welding residual stresses and metallurgical change, which increase the crack driving force and reduce the resistance of brittle fracture as well as environmental fracture. This is a serious problem with many alloys as well as A106 Gr B steel pipe. This pipe, used in petrochemical and heavy chemical plants, either degrades due to corrosive environments, e.g., chlorides and sulfides, and/or becomes damaged during service due to the various corrosion damage mechanisms. Thus, in this study, the sulfide corrosion fatigue strength of multi-pass welded A106 Gr B steel pipe was evaluated in a 5.0 wt.% NaCl solution that was saturated with H2S gas at room temperature on the basis of NACE TM 0177-90. The crack growth characteristics of the welded pipe were then assessed at the low limit of sulfide corrosion fatigue strength, which was previously obtained from the sulfide corrosion fatigue (SCF) tests. From the results, in terms of the SCF, all the specimens failed at the heat-affected zone, where a high welding residual stress distributes. It was found that the fatigue crack grew at the low corrosion fatigue limit (σ _{SCFun-notched}), which was 32 % (160MPa) of the ultimate tensile strength (502MPa) of the welded specimens.     

SiO2/TiO2 Composite Film for High Capacity and Excellent Cycling Stability in Lithium‐Ion Battery Anodes

In this study, partially crystalline anodic TiO₂ with SiO₂ well‐distributed througout the entire oxide film is prepared using plasma electrolytic oxidation (PEO) to obtain a high‐capacity anode with an excellent cycling stability for Li‐ion batteries. The micropore sizes in the anodic film become inhomogeneous as the SiO₂ content is increased from 0% to 25%. The X‐ray diffraction peaks show that the formed oxide contains the anatase and rutile phases of TiO₂. In addition, X‐ray photoelectron spectroscopy and energy‐dispersive X‐ray analyses confirm that TiO₂ contains amorphous SiO₂. Anodic oxides of the SiO₂/TiO₂ composite prepared by PEO in 0.2 m H₂SO₄ and 0.4 m Na₂SiO₃ electrolyte deliver the best performance in Li‐ion batteries, exhibiting a capacity of 240 µAh cm^?2 at a fairly high current density of 500 µA cm^–2. The composite film shows the typical Li–TiO₂ and Li–SiO₂ redox peaks in the cyclic voltammogram and a corresponding plateau in the galvanostatic charge/discharge curves. The as‐prepared SiO₂/TiO₂ composite anode shows at least twice the capacity of other types of binder‐free TiO₂ and TiO₂ composites and very stable cycling stability for more than 250 cycles despite the severe mechanical stress.