GaAs多频段数控0°～360°移相器

本文介绍了一种可以复盖ＵＨＦ,Ｌ、Ｓ和Ｃ波段的ＧａＡｓ单片有源移相器。该装置与一个９０°混合耦合电路结合、能产生以１１．２５°阶跃的,从０°￣９０°的相移,窄波段使用时,数控相移误差在２°以内,而在频率１￣８ＧＨｚ内改变相位时,最大相位误差不大于５°,最大幅度变化不大于２．５ｄＢ,芯片尺寸为４５×４５×２０密耳。文中讨论了多波段、多倍频程移相器的应用。     

Development of 1232°C (2250°F) Erosion and Impact Tests for Thermal Barrier Coatings

High temperature erosion and impact texts were developed for evaluation of thermal barrier coating (TBC) systems that are being generated for the High-Speed Civil Transport supersonic aircraft under NASA's Enabling Propulsion Materials program. The TBC-coated test specimen is a 6.1-mm (0.24-inch) diameter cylindrical pin. Twelve pins are mounted on a carousel with a pitch diameter of 46 mm (1.813 inch). This carousel is rotated at 500 rpm, 50 mm (two inches) from the combustor exhaust of a burner rig, while the TBC temperature is controlled at 1232°C (2250°F) using a pyrometer. The particulate is injected radially into the combustor in two horizontally opposed positions.

Two separate types of particulate are used in the tests: 50-micron and 560-micron crushed alumina. The effects of the 50-micron erosion and 560-micron impact tests are quite different, but in each case excellent similarity is seen between damage to test specimens and that of commercial engine service hardware. The temperature of the impinging particulate is above 1450°C (2642°F), and the particulate velocities were determined to be. 174 and 9 meter/second (570 and 30 feel/second), respectively, for the 50-micron and 560-micron materials.

A mathematical expression was developed for erosion wear as a function of particle size, velocity, hardness and density. The ranges over which these parameters were varied are particle size 10 to 180 micron, velocity 107 to 332 meter per second, hardness 820 to 2100 kg/mm² Knoop, density 2.2 to 5.7 gram/cc. Erosion wear is linear with the accumulated mass of eroding particulate used. Impact wear caused by 560-micron alumina is distinctly nonlinear.     

Modeling and Measurement of Aryl Phosphate Ester Vapor Pressures at 50°C

The vapor pressure of TCP was determined by measuring the loss rate under vacuum conditions at 50°C. The mass loss of a four-component aryl phosphate ester additive mixture was also measured. The loss-rate was modeled, and the component vapor pressures were determined by fitting the model to the experimental loss data. The values measured were significantly lower than those obtained through extrapolation of higher-temperature vapor pressure data.     

Test of a Fluid-Film Wave Bearing at 350°C with Liquid Lubricants

A novel fluid-film wave bearing has been run at a higher temperature (350°C) than ever before with a perfluoropolyether (PFPE)-K liquid lubricant. Additionally, the wave journal bearing (45 mm diameter and 24 mm long) completed an 8-h endurance test at the NASA Glenn Research Center. The lubricant was PFPE-K XHT 500. After being maintained at 350° C for 8 h, the bearing temperature was raised to 356°C for the last 30 min of the run. The speed was 29,000 rpm and the load ranged from 2670 to 3560 N. The bearing was perfectly stable both dynamically and thermally. The observed temperature was more than 150°C above that run with current turbine engine lubricants. The use of high-temperature bearings as tested here would allow efficiency increases of more than 5% in aero or terrestrial turbine engines.     

MZK—F0的故障分析与F0值监控仪的校正

F_。值法灭菌近年以来药厂和医院制剂室在大输液生产中代替了普通湿热灭菌法,是我国大输液生产灭菌史上的重大进步。它改变了升温15分钟,115℃恒温30分钟等固定程序的传统灭菌工艺,具有更科学性,消除了由于蒸汽压力过高或过低而引起的升温时间过长或过短造成的5-HMF超标或灭菌不彻底的状态。重庆小型自动化装置厂生产的MZK-F_。灭菌柜智能控制器是国内较早推出专为大输液F_。值法灭菌,提供安全可靠的控制装置。我们使用时间较早。但在使用中,如何处理常见故障对F_。值监控仪的精度校正,对使用者来说显得很有必要。     

Antiwear Film Formation by ZnDTP,Detergent, and Dispersant Components of Passenger Car Motor Oils—Part II: Effects of Low-Molecular-Weight Dispersant on Film Formation

Passenger car motor oils (PCMOs) are undergoing a rapid evolution. Studies have found that some exhaust emission catalysts may be deactivated by phosphorus, largely derived from zinc dialkyldithiophosphate (ZnDTP), the mainstay antiwear and antioxidant agent in PCMO formulations for the past 50 years. Consequently, future engine oils will contain significantly reduced phosphorus levels. Since ZnDTP is the dominant antiwear and antioxidant in current PCMOs, lower phosphorus content will impact engine oil formulation strategies.

To better understand the effects of ZnDTP reduction on wear control, electrical contact resistance (ECR) studies have been carried out on blends containing ZnDTP, detergent, and low-molecular-weight (LMW) succinimide dispersant. In contrast to previous results obtained with high-molecular-weight (HMW) dispersant, the combination of ZnDTP and LMW dispersant gave an ECR trace closely resembling that of ZnDTP alone. Thus, the chemical structure of the succinimide dispersant can have a profound effect on ZnDTP antiwear film formation. ECR experiments on three-way combinations of ZnDTP + LMW succinimide dispersant + overbased phenate detergent provided a much better film than that from a similar formulation using an HMW succinimide dispersant. This study demonstrates that the ECR experiment is sensitive to the chemical structures of components controlling the function of modern PCMOs, making ECR a convenient tool to optimize the performance of the remaining ZnDTP in lower phosphorus PCMO formulations.     

F0SSIL的手表王国

并非赫赫有名的Fossil实际上是一个很大的公司。许多人，尤其是钟表业的人士，经常忽视Fossil。毕竟它的产品主要是一些石英的廉价时装表。这个公司实际上有多大？Fossil在创造着惊人的销售额！[编者按]     

Wear test of cemented tungsten carbide at high atmospheric temperature (400°C)

Cemented tungsten carbide–cobalt (WC–Co) alloy has good mechanical properties, so it is widely used for cutting tools, wear-resistant dies and rolls, and shock-resistant punching dies. In this study, a wear test between cemented WC–Co alloy and carbon steel is carried out using a pin-on-disc wear-testing machine. The characteristics as to wear rate, coefficient of friction and surface roughness are investigated. Pin specimen and disc specimen surfaces are analyzed by a fluorescent X-ray analyzer. In addition, the wear characteristics of WC–Co alloy are confirmed by SEM observation of the microstructure of the cemented WC–Co alloy specimen. This revised version was published online in August 2006 with corrections to the Cover Date.     

Experimental study of the enhanced ion backscattering yield at 180° and its depth dependence

A magnetic deflection system has been developed which enables the backscattering (RBS) yield to be measured within a small (0.04°) angular cone centred exactly at 180°. Using this system, we have investigated the magnitude and depth dependence of the 180° RBS yield enchancement effect. In a wide variety of targets, we obtain enhancements greater than a factor of 2; in all cases the maximum enhancement was observed not at the surface (as reported recently by Kirsch and Poizat) but at depths of 7–20 nm beneath the surface. In the case of Au, the observed enhancement was independent of temperature and hence of vibrational amplitude, over the range 300–800 K. A series of thin amorphous WO₃ films on monocrystalline W has enabled the depth dependence of the effect to be studied in considerable detail. We have also measured the scattering from Bi in a set of Bi-implanted targets (C, Si and Ge) in order to investigate the effect of medium- and low-mass substrates. The yield enhancements are large, i.e. greater than two-fold. This is in marked contrast to earlier measurements of scattering from (unimplanted) targets of low atomic mass.     

1000°F工作环境下的不锈钢紧固件

热交换器正常工作温度达1000°F(约283℃)时,用不锈钢制成的螺栓却生锈了!这是为什么呢?原来,在较高温度时,热循环会使某些不锈钢变成非不锈钢。所以选择紧固件材料上一定要慎重,以免发生意外。——MC编者按     

Dry sliding wear behavior of TC11 alloy at 500 °C: Influence of laser surface texturing

Six types of micro-textures with different diameters and area densities are produced on the surfaces of the TC11 alloy. The wear characteristics of the textured and untextured surfaces are investigated at 500 °C. It is found that the regular textured surface enhances the amount of oxygen adsorbed on the material surfaces, which promotes the formation of more tribo-oxides on the textured surface compared to the untextured samples, and thus significantly enhances the anti-wear ability of the TC11 alloy. A micro-dimpled structure with relatively small-diameter and high-density is likely to improve the tribological properties of TC11 alloy at 500 °C.     

The Performance of PS400 Subjected to Sliding Contact at Temperatures from 260 to 927°C

Adequate high-temperature lubrication between loaded surfaces in sliding contact can be one of the most challenging tribological problems confronting today's designers. In an attempt to provide a possible solution a test program was initiated to evaluate PS400, a recently patented, high-temperature solid lubricant coating. Made from nickel–molybdenum–aluminum, chrome oxide, silver, and barium fluoride–calcium fluoride, PS400 is a variant of the earlier coating, PS304, but is formulated for higher density, smoother surface texture, and greater dimensional stability. It was initially developed to minimize the start–stop wear in foil air bearings but is expected to perform well in other high-temperature applications where sliding friction and wear are a concern, such as variable inlet guide vanes and process control valve stems. To better define its operational capabilities, a series of tests was conducted to study the behavior of PS400 under reciprocating sliding contact at temperatures from 260 to 927°C. The tests were performed on stationary, uncoated cobalt-based superalloy bushings loaded against reciprocating PS400-coated shaft specimens in a flat-on-cylinder configuration at Hertz contact pressures from 14.1 to 20.1 MPa. For tests conducted below 927°C, friction coefficients ranged from 0.37 to 0.84 with wear factors on the order of 10^?5 and 10^?6 at the high temperatures but substantially increased at the lowest temperature. Data collected at 927°C were limited because the coating was found to be dimensionally unstable at this temperature.     

F0-01手提式滤油机的设计

介绍了此滤油机的结构设计方案及此设计应用的优越性，此滤油机适用于发电、供电、机械及优化行业的变压器油、润滑油、冷却油等油液的过滤、再生。     

Correlation Study of Different Shear Stability Test Methods for Hydraulic Oils

Nowadays, different shear stability test methods for hydraulic oils are favored differently by different original equipment manufacturers (OEMs) or in different regions. Therefore, correlation studies between these test methods are becoming very important. In this articles, the correlations among three popular shear stability test methods for hydraulic oils were investigated. In addition, the relationship between these methods and the pump test was investigated. The results showed that the sonic shear test and bearing shear test showed a good correlation in terms of both viscosity loss and shear stability index (SSI). The viscosity change during the pump test can be reproduced both by sonic and bearing shear test methods and the relationship the between bearing shear test and pump test is almost consistent depending on different data sets.     

Comparison of Leakage Performance in Three Types of Gas Annular Seals Operating at a High Temperature (300°C)

Adequate sealing in rotating machinery reduces secondary leakage and results in more efficient and stable systems. Labyrinth seals are most common, although brush seals are popular in specialized applications. The hybrid brush seal (HBS) is a novel design that adds to the bristle brush matrix a number of cantilever pads that rest on the rotor surface. Upon shaft rotation the pads lift due to the generation of a hydrodynamic gas film, and the brushes effectively seal an upstream pressure. Hence, the HBS has no wear and no local thermal distortion effects. This article presents measurements of leakage versus pressure differential obtained in a three-tooth labyrinth, a conventional brush seal, and a hybrid brush seal for operation at high temperature (300°C) and with shaft surface speeds to 26 m/s. The measurements demonstrate that the HBS leaks ～ 31% less than a standard brush seal and is significantly better (～ 68%) than a similarly sized labyrinth seal. As temperature increases, the labyrinth seal leakage decreases because its clearance changes due to the thermal growth of the components. The HBS, on the other hand, shows leakage that is nearly insensitive to air inlet temperature. The measurements demonstrate HBS as a reliable seal technology for use in gas turbines, for example.     

动态光散射在F0F1-ATPase制备过程中的应用

采用超声波破碎菌体、DEAE阴离子柱和Superdex200分子筛柱联用法得到较纯的F0F1-ATPase全酶,并得到SDS-PAGE电泳和动态光散射检测确认。动态光散射检测显示,F0F1-ATPase分子团尺寸随温度升高而增加,不同于普通胶体和单亚基蛋白,判断与F0F1-ATPase的多亚基结构有关。研究表明,动态光散射技术是检测蛋白质均一性和稳定性的有效手段。     

The unlubricated reciprocating sliding wear of 316 stainless steel in CO2 at 20–600°C

The friction and wear behaviour of 316 stainless steel in CO₂ has been investigated in the load range 8–50 N from 20 to 600°C. Wear transitions occurred at all temperatures but were load-dependent. At and below 300°C, wear transitions only took place at low loads, whereas above 300°C transitions were observed at all loads. The low temperature wear transition, representing an order of magnitude decrease in wear rate, was associated with a change in friction behaviour. The friction force across the specimen was initially widely fluctuating but after a time, which did not necessarily coincide with the wear transition, became much smoother. The smoother sliding is thought to indicate a trend to oxide-oxide contacts. At higher temperatures wear transitions result in a two orders of magnitude reduction in wear. The corresponding friction transition was similar to the low temperature friction change but also included a marked temporary drop in the coefficient of friction.Pits or troughs up to 450 μm deep were seen in wear scars above 400°C. It is proposed that isolated sections of grooves formed during the initial stages of wear become back-filled with loosely adhering oxide particles. These troughs are then further deepened, possibly by abrasive fretting action of the semi-fluid oxide material.     

Estimation of the Reliability of the Gear–Motor System Using a Markov Model

Journal of Machinery Manufacture and Reliability - In this article, the reliability of a gear–motor system is analyzed on the condition that the failure of the gear leads under certain...