GaN材料的GSMBE生长

在国内首次用ＮＨ３作氮源的ＧＳＭＢＥ方法在α－Ａｌ２Ｏ３衬底上生长出了ＧａＮ单昌外延膜。ＧａＮ生长速率可达０．５μｍ／ｈ。ＧａＮ外延膜的（０００２）双晶Ｘ射线衍射峰回摆曲线的半高宽最窄为８ａｒｃｍｉｎ。霍尔迁移率为５０ｃｍ＾２／Ｖ．ｓ。对质量好的ＧａＮ膜，室温阴性发光谱上只有一个强而锐的近岸边发光峰，谱峰位于３７２ｎｍ处，谱峰半高宽为１４ｎｍ（１２５ｍｅＶ）。     

GaN的MOVPE生长和m－i－n型蓝光LED的试制

利用自行研制的常压ＭＯＶＰＥ设备和全部国产ＭＯ源，采用低温生长缓冲层技术，在蓝宝石（α－Ａｌ２Ｏ３）衬底上获得了高质量的ＧａＮ外延层。未掺杂的ＧａＮ外延层的室温电子迁移率已达１１４ｃｍ２／Ｖ．ｓ，载流于浓度为２×１０１８。７７Ｋ光致发光谱近带边发射峰波长为３６５ｎｍ，其线宽为４ＤｍｅＶ。Ｘ射线双晶衍射回摆曲线的线宽为３６０ａｒｃｓｅｃ。用Ｚｎ掺杂生长了绝缘的ｉ－ＧａＮ层。在此基础上研制了ｍ－ｉ－ｎ型ＧａＮ的ＬＥＤ，并在室温正向偏压下发出波长为４５５ｎｍ的蓝光。     

掺Si对MOCVD生长的GaN单晶膜的黄带发射及生长速率的影响

对ＭＯＣＶＤ生长ＧａＮ：Ｓｉ薄膜进行了研究,研究表明随ＳｉＨ４／ＴＭＧａ流量比增大,ＧａＮ：Ｓｉ单晶膜的电子浓度增大,迁移率下降,Ｘ射线双晶衍射峰半高宽增加,同时这发射强度得到了大大的提高,并报导了随ＳｉＨ４／ＴＭＧａ流量比增大,ＧａＮ：Ｓｉ的生长速率降低的现象,研究结果还表明,预反应对ＧａＮ：Ｓｉ单晶膜黄带发射影响很大,预反应的减小可以使黄带受到抑制。     

GaAs－InP复合材料的外延生长方法及金属半导体场效应晶体管器件制备

提出了一种新的生长过渡层的方法，并利用低压金属有机气相外延技术在ＩｎＰ衬底上生长出高质量ＧａＡｓ外延材料，用Ｘ射线双晶衍射测得５μｍ厚ＧａＡｓ外延层的（００４）晶面衍射半峰高宽（ＦＷＨＭ）低至１４０ａｒｃｓｅｃ。并制出ＧａＡｓ金属半导体场效应晶体管（ＭＥＳＦＥＴ），其单位跨导为１００ｍｓ／ｍｍ，可满足与长波长光学器件进行单片集成的需要。     

提高Si3N4抗氧化性能的陶瓷涂层

采用Ｓｏｌ－Ｇｅｌ法在热压Ｓｉ３Ｎ４表面涂上一层ＳｉＯ２涂层，用Ｘ光电子能谱（ＸＰＳ）检测了涂覆ＳｉＯ２后Ｓｉ３Ｎ４表面的组成，结果表明，在Ｓｉ３Ｎ４表面有ＳｉＯ２涂层存在，经涂覆 热压Ｓｉ３Ｎ４在１３０℃氧化１００ｈ后，氧化增重从未涂覆的０．４２ｍｇ／ｃｍ＾２降到０．２８ｍｇ／ｃｍ＾２。     

p~＋－GaInAsSb／p－GaInAsSb／n－GaSb异质结红外控测器

ＧａＩｎＡｓＳｂ是红外探测器中重要的半导体材料之一。我们用水平常压金属氧化物化学气相淀积（ＭＯＣＶＤ）技术在ｎ型ＧａＳｂ衬底上成功地生长了ＧａＩｎＡｓＳｂ外延层，用ＰＬ谱、红外吸收谱、Ｘ射线衍射和扫描电子超声显微镜（ＳｃａｎｎｉｎｇＥｌｅｃｔｒｏｎＡｃｏｕｓｔｉｃＭｉｃｒｏｓｃｏｐｙ，ＳＥＡＭ）等实验手段对ＧａＩｎＡｓＳｂ外延层进行了表征。用ＧａＩｎＡｓＳｂ材料制作的红外探测器的光谱响应的截止波长达２．４μｍ，室温探测率Ｄ＊达１×１０９ｃｍＨｚ（１／２）／Ｗ，２．２５μｍ波长时的量子效率为３０％。本文首次给出了ＧａＩｎＡｓＳｂ外延层的扫描电子超声显微镜像（ＳＥＡＭ像），为扫描电子超声显微镜在半导体材料方面的应用开辟了一个新的领域。     

NH3-MBE生长极化场二维电子气材料

介绍了用ＮＨ３－ＭＢＥ技术在蓝宝石Ｃ面上外延的高质量的ＧａＮ单层膜以及ＧＮ／ＡｌＮ／ＧａＮ极化感应二维电子气材料。外延膜都是Ｎ面材料。形成的二维电子气是“倒置二维电子气”。ＧａＮ单层膜的室温电子迁移率为３００ｃｍ＾２／Ｖｓ。二维电子气材料的迁移率为６８０ｃｍ＾２／Ｖｓ（ＲＴ）和１７００ｃｍ＾２／Ｖｓ（７７Ｋ）,相应的二维电子气的面密度为３．２＊１０＾１３ｃｍ＾－２（ＲＴ）和２．６ｘ１０＾１３ｃｍ＾     

GaAs—InP复合材料的外延生长方法及金属半导体场效应晶体管器件制备

提出了一种新的生长过渡层的方法，并利用低压金属有机气相外延技术在ＩｎＰ初底上生长出高质量ＧａＡｓ外延材料，用Ｘ射线双晶衍射测得５μｍ厚ＧａＡｓ外延层的晶面衍射半峰高宽（ＦＷＨＭ）低至１４０ａｒｃ ｓｅｃ。并制出ＧａＡｓ金属半导体场效应晶体管（ＭＥＳＦＥＴ），其单位跨导为１００ｍｇ／ｍｍ，可满足与长波长光这器件进行单片集成的需要。     

Si基GaN上的欧姆接触

研究了Ｓｉ基ＧａＮ上的欧姆接触,对在不同的合金化条件下铝（Ａｌ）和钛铝铂金（Ｔｉ／Ａｌ／Ｐｔ／Ａｕ）接触在不同的合金下的性质作了详尽的分析。Ａｌ／ＧａＮ在４５０℃氮气气氛退火３ｍｉｎ取得最好的欧姆接触率７．５＊１０＾－３Ω．ｃｍ＾２,而Ｔｉ／Ａｌ／Ｐｔ／Ａｕ／ＧａＮ接触在６５０℃氮气气氛退火２０ｓ取得最好的欧姆接触８．４＊１０＾－５Ω．ｃｍ＾２,而且Ｔｉ／Ａｌ／Ｐｔ／Ａｕ／ＧａＮ接触有较好的热稳定     

GexSi1-x材料生长的改善

利用超高真空化学相淀积（ＵＨＶ／ＣＶＤ）系统在６５０℃生长出表面光亮的ＧｅＳｉ单晶。在１２００Ｌ／ｍｉｎ分子泵与前级机械泵间串接４５０Ｌ／ｍｉｎ分子泵,改善了生长环境。串接分子泵后生长的样品的Ｘ射线双晶衍射分析表明,外延层衍射峰半宽仅为１９８ａｒｃｓｅｃ,且出现了Ｐｅｎｄｅｌｌｏｓｕｎｇ干涉条纹,说明外延层结晶质量很好。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.