低真空超薄层碳氮共渗研究

介绍了低真空化学热处理多用炉及其工艺特征，讨论了低真空脉冲式碳氮共渗的试验研究结果，试验和应用表明，在７５０￣８４０℃进行低真空脉冲碳氮共渗，能够简便可靠地实现硬化层深度０．１￣０．３ｍｍ和表面硬度≥５８ＨＲＣ的超薄层高硬度碳氮共渗处理。     

对珠三角地区模具材料及热处理行业中若干问题的评述

评述了珠三角地区在模具钢选择,提高模具寿命,渗氮、渗碳新技术,渗氮后的变形等问题,并就制止劣质模具钢泛滥方面提出了一些建议。     

Silicon Epitaxial Wafer for X Band Double Read－type DDR IMPATT Diodes by Atmosphere／Low Pressure Growth Techniqt

ＳｉｌｉｃｏｎＥｐｉｔａｘｉａｌＷａｆｅｒｆｏｒＸＢａｎｄＤｏｕｂｌｅＲｅａｄ－ｔｙｐｅＤＤＲＩＭＰＡＴＴＤｉｏｄｅｓｂｙＡｔｍｏｓｐｈｅｒｅ／ＬｏｗＰｒｅｓｓｕｒｅＧｒｏｗｔｈＴｅｃｈｎｉｑｔＷａｎｇＸｉａｎｇｗｕａｎｄＬｕＣｈｕｎｙｉ王向武，陆春...     

Nano-multilayer Ti-Zr-N coating by a central configured multi-arc coating process

In this work, a novel arc ion plating (AIP) system, consisting of a centrally configured multi-arc source array (CCMA), is developed. This system is aimed to satisfy the present industrial demands for the large-scale production of multicomponent, multilayered, and superlattice coatings. The central array is made up of three flat, independently powered, arc sources. These form a triangular pillar.The newly developed CCMA AIP system is used to deposit TiN/ZrN coatings, in order to evaluate its performance. The surface hardness of the specimens is measured by micro Vickers indentation. A scratch test is used to determine the adhesive strength of the coatings. Scanning electron microscopy (SEM) is used to observe the cross-sectional morphology and to measure the film thickness. An energy dispersive spectrometer (EDS) is used to characterize film composition. The crystal structures of the coatings are characterized by an X-ray diffractometer and transmission electron microscope (TEM).The deposited coatings range from a micro- to nano-layered (TiN/ZrN) structure as the rotation speed of the substrate table was increased. Each layer exhibits a (111) preferred orientation. At rotating speeds in excess of 10 rpm, a nano-multilayered Ti(Zr)N structure is formed, again with each layer having (111) preferred orientation. At the highest rotation speeds the greatest surface hardness and film adhesion strength are attained. This is attributed to the maximized stress accommodation of the nano-multilayer structure, through the different shear elastic modulus of each layer. This research demonstrates that this novel CCMA AIP system is highly flexible in coating material design and capable of mass production.     

加工低凝环烷基原油的常减压装置的腐蚀与防护

针对辽河石化分公司改造后的南蒸馏装置加工低凝环烷基原油中发生的腐蚀情况,进行了腐蚀机理分析,提出了相应的防护措施,为实现装置三年一修的目标提出一些建议。     

Nanoscale surface patterning of diamond utilizing carbon diffusion reaction with a microstructured titanium mold

A novel method was proposed for generating nanoscale surface patterns on single-crystal diamond by carbon diffusion with a microstructured titanium mold under controlled temperature and pressure. The depth, geometry, and surface integrity of the fabricated patterns were investigated by laser micro-Raman spectroscopy and white-light interferometry, and the titanium molds were analyzed by energy dispersive X-ray spectroscopy. The results showed that at specific temperatures and pressures, three-dimensional patterns with a depth of tens of nanometers and sloped/curved walls could be generated on a diamond surface after a few minutes, without causing any surface graphitization. The intensity profile and penetration depth of carbon atoms into the titanium were experimentally measured.     

准一维纳米材料的合成及其研究进展

准一维纳米材料(纳米管、纳米线、纳米电缆、纳米带等)具有特异的物理、化学性质，并在未来纳米器件中具有潜在的应用价值，因此成为纳米材料领域中的研究热点。着重介绍了准一维纳米材料的合成方法：气相法、液相法和模板法。介绍了各种不同方法的生长条件和形成机制，并展望了准一维纳米材料的研究趋势。     

An ab initio study of Ti-Y-O nanocluster energetics in nanostructured ferritic alloys

So-called oxide dispersion strengthened steels or nanostructured ferritic alloys (NFAs) contain nanoprecipitates which give them exceptional mechanical properties and resistance to radiation effects. However, the structure and composition of these nanoprecipitates are still uncertain. To help clarify the nature of the smallest nanoprecipitates, density functional theory calculations are used to investigate the most stable Ti, Y, and O nanocluster computational units in Fe. Two distinct methods for searching for stable nanoclusters are proposed: one in which nanoclusters are restricted to the body-centered cubic Fe lattice and one in which the nanocluster structures are strained variants of bulk Ti and Y oxides. We discovered that nanoclusters that are structurally similar to bulk Ti and Y oxides are significantly more stable than nanoclusters that are restricted to the Fe lattice. Consequently, the most stable nanoprecipitates in Ti-Y-O NFAs are more likely to be small oxide phases than coherent solute-enriched clusters.     

Investigation on effect of pulse frequency on nanostructure and electrocatalytic active surface area of platinum pulse electroplated on niobium

Abstract

The electrocatalytic active surface area is an important parameter in platinum anodes. In this research, the effect of frequency, a pulse electroplating parameter, on the nanostructure of platinum plated on niobium has been studied. The experiments were performed in a Q salt solution, based on platinum tetraammine, at a duty cycle of 30%, at an electrolyte temperature of 93°C, pH?=?10·5, and in a frequency range of 2·5 to 90 Hz. The electrocatalytic active surface area of the coatings was estimated by cyclic voltammetry and the nanostructure of the coatings was studied by scanning electron microscopy and atomic force microscopy. The results showed that the highest electrocatalytic active surface area is obtained at an optimum frequency of 15 Hz. The cone shaped nanostructure of the coating at this frequency is such that the area is 10% more than the typical semi spherical platinum coating, whereas at other frequencies, the surface becomes monotonous and smooth.     

Structure and mechanical properties of arc evaporated Ti-Al-O-N thin films

The structure, mechanical properties, and machining performance of arc evaporated Ti-Al-O-N coatings have been investigated for an Al_0.66Ti_0.34 target composition and O₂/(O₂+N₂) gas flow-ratio varied between 0 to 24%. The coating structure was analysed using SEM, EDX, XRD, XPS, TEM, and STEM. Mechanical properties were analysed using nanoindentation and the deformation behaviour was analysed by probing the nanoindentation craters. The coatings performances in cutting tests were evaluated in a turning application in low carbon steel (DIN Ck45). It is shown that the addition of oxygen into the arc deposition process leads to the formation of a dual layer structure. It consists of an initial cubic NaCl-structure solid solution phase formed closest to the substrate, containing up to 35 at.% oxygen (O/O+N), followed by steady-state growth of a nanocomposite compound layer comprised of Al₂O₃, AlN, TiN, and Ti(O,N). The addition of oxygen increases the ductility of the coatings, which improves the performances in cutting tests. At high levels of oxygen, (> 13 at.%), however, the performance is dramatically reduced as a result of increased crater wear.     

Catalyst-free synthesis, growth mechanism and optical properties of multipod ZnO with nanonail-like legs

Multipod ZnO with nanonail-like legs was synthesized successfully by a facile combustion oxidation method at 880 °C without any catalysts. The morphologies of three samples obtained from three growth stages, namely sprout, growing and multipod with nanonail-like legs, were investigated. The possible growth mechanism was discussed in detail. Compared with the other two structures, the multipod with nanonail-like legs exhibited a significant enhancement in the green emission region. Its unique structure together with its good optical properties suggest that it is a promising candidate for the fabrication of optical nanodevices.     

Zirconia coatings deposited by electrostatic spray deposition. Influence of the process parameters

The influence of electrostatic spray deposition (ESD) process parameters such as the substrate temperature, the precursor solution flow rate and the nozzle-to-substrate distance on the morphology of YSZ thin coatings was studied. Each parameter was studied separately and the correlation between them was found in order to optimise the experimental conditions where dense, continuous zirconia coatings can be successfully deposited.     

Preparation of nanostructured high-temperature TZM alloy by mechanical alloying and sintering

Mechanical milling proceeded by sintering was used to synthesize nanostructured temperature-resistant TZM alloy. Milling under Ar for different times (1, 2, 3, 5, 10, 15, 20, 25, and 30 h) and sintering at 1500, 1600 and 1700 °C for 30, 45, 60 and 90 min resulted in increasing of low-energy grain boundaries (LEGBs) and dispersion of TiC and ZrC with a size of ~ 65 nm in the matrix near LEGBs. Morphology and grain size of the products were determined from scanning electron microscope (SEM) images and X-ray diffraction (XRD) patterns, almost precisely. Optimum density of nanostructured TZM alloy ~ 9.95 ± 0.01 g/cm³ was achieved by sintering at 1700 °C for 90 min.     

Thermal stability of superhard Ti-B-N coatings

Ternary transition-metal boron nitride Ti-B-N offers outstanding hardness and thermal stability, which are increasingly required for wear resistant applications, as the protective coatings are subjected to high temperature, causing thermal fatigue. Ti-B-N coatings with chemical compositions close to the quasibinary TiN-TiB₂ tie line and boron contents below ∼ 18 at.% contain a crystalline supersaturated NaCl structure phase, where B substitutes for N. Annealing above the deposition temperature causes precipitation of TiB₂, which influence dislocation mobility and hence the hardness of TiB_0.40N_0.83 remains at a very high level of ∼ 43 GPa with annealing temperature T_a up to 900 °C. Growth of Ti-B-N coatings with B contents above ∼ 18 at.% results in the formation of nm sized TiN and TiB₂ crystallites embedded in a high volume fraction of disordered boundary layer. The compaction of this disordered phase during annealing results in a hardness increase of TiB_0.80N_0.83 coatings from the as-deposited value of ∼ 37 GPa to ∼ 42 GPa at T_a = 800 °C. Excess B during growth of TiB_2.4 coatings causes the formation of bundles of ∼ 5 nm wide TiB₂ subcolumns encapsulated in a B-rich tissue phase. This nanocolumnar structure is thermally stable up to temperatures of ∼ 900 °C, and consequently the hardness remains at the very high level of ~ 48 GPa, as nucleation and growth of dislocations is inhibited by the nm sized columns. Furthermore, the high cohesive strength of the B-rich tissue phase prevents grain boundary sliding.     

Surface contact degradation of multilayer ceramics under cyclic subcritical loads and high number of cycles

Alumina/alumina–zirconia ceramic laminated composites produced by tape casting present a compressive residual stress at the alumina surface due to the thermal expansion mismatch between layers developed during processing. Because of this residual stress, the mechanical properties at the surface, such as wear or surface fracture, have proven to be better than the properties of a monolithic stress-free alumina. In a previous work, it was shown that this laminate composite has better resistance to the development of a ring crack when loaded with a spherical indenter, under both cyclic and static loads below the critical load for cone cracking. In this work, cyclic Hertzian indentations with subcritical loads are performed on the same laminate ceramic and a monolithic alumina, but with a higher number of cycles than the necessary to provoke the first damage (ring crack). Results show that for low and intermediate number of cycles, the laminated composite presents better resistance to damage than the monolithic alumina. However, for high number of cycles, spalling at the surface of the laminate material appears, whereas the monolithic alumina develops secondary cone cracking. This difference is attributed to the fact that laminate ceramics present an enhanced apparent fracture toughness of the material, which implies a higher quasi-plasticity due to shear driven microcracking. For a high number of cycles, these microcracks grow until coalescence at the surface, provoking exfoliation of the material at the contact area, enhanced by the fact that the indented and the indenter material have different elastic properties.     

真空回火炉着色问题的探讨

叙述了模具钢经真空回火后的着色现象以及真空回火的必要性.     

Structural and mechanical properties of AlTiN/CrN coatings synthesized by a cathodic-arc deposition process

Monolayered AlTiN and Multilayered AlTiN/CrN coatings were synthesized by a cathodic-arc deposition process, using TiAl (with 50/50 and 33/67 at.%) and Cr elemental cathodes. The atomic ratio of Al/(Ti + Al) in the AlTiN coatings was reduced to 0.44 and 0.61, respectively, compared with the corresponding Ti₅₀Al₅₀ and Ti₃₃Al₆₇ cathode materials. The multilayered AlTiN/CrN films showed smaller crystallite size, larger lattice strain, higher hardness, higher residual stress, and better adhesion strength as well than the monolayered AlTi films. The multilayered Al_0.35Ti_0.22N_0.43/CrN coating exhibited the highest hardness of about 38 GPa and the highest H³/E*² ratio value of 0.188 GPa, indicating the best resistance to plastic deformation, among all the coatings studied.