共查询到19条相似文献,搜索用时 218 毫秒
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直喷式柴油机燃烧系统的均匀试验设计研究 总被引:5,自引:2,他引:3
在SD195柴油机涡流室改直喷过程中,采用了均匀设计试验法优化柴油机性能,用均匀设计表安排了采用浅W燃烧系统柴油机的燃烧室尺寸、油嘴喷孔直径和油嘴伸出量对性能影响的试验,经回归分析得到了最佳的试验结果。用单因素试验法分析了诸因素对性能的影响规律,发现燃烧室尺寸对性能有重大影响,在考虑交互作用情况下,油嘴孔径、伸出量的参数选择时要综合考虑燃烧室尺寸,试验最终获得良好效果。同时证明了均匀设计法的有效性,表明均匀设计试验法是安排多水平试验的良好方法。 相似文献
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热压烧结法是将干燥粉料充填入模型内,从单轴方向边加压边加热,使成型和烧结同时完成。与常规冷压烧结法相比,热压烧结法所制备的复合材料的晶粒更加细小,增强相分布更加均匀,故其综合性能更加优异。由于采用热压烧结法生产特殊的碳铜复合材料没有专用模具,在研究该材料生产工艺过程中,需要对相应的模具进行设计研究。本文根据生产中所遇到的问题,结合实际情况,设计开发出一种新型的热压模具,以配合碳铜复合材料的试验生产,提高生产效率。 相似文献
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目前设计碳钢焊条时,采用的经验公式中的抗拉强度碳当量(Ct)或下屈服强度碳当量(Cy)含有碳、锰、硅、钙、铬等元素换算成的碳当量,但没有确切的稀土元素换算成的碳当量,不适用于含稀土元素的焊条设计.因此,在新型焊条药皮配方开发研制中,采取药皮过渡适量的镧钇元素,通过5种典型配方的熔敷金属的力学性能试验,利用Matlab函数辅助计算,曲线拟合得出含镧钇元素的熔敷金属抗拉强度(σb)和下屈服强度(σsL)定量公式,三维强度极限网状图,可预知多元稀土配方熔敷金属的σb和σsL值.结果表明,通过采用定量公式可以解决镧钇元素在现有经验公式中不能被换算成碳当量的问题,可以解决经验公式误差较大的问题,尤其能显示镧钇元素添加量与低碳钢焊条熔敷金属力学性能间的定量影响关系. 相似文献
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真空压力浸渗制备低体积分数SiCp/LY12复合材料的组织和性能研究 总被引:4,自引:0,他引:4
采用真空压力浸渗法成功制备出低体积分数(30-35%)SiCp/LY12复合材料,并通过微观结构及力学性能测定,研究了预制件备工艺对复合材料质量的影响。结果表明,合适的粘结剂及加入量是制备低体积分数SiCp/LY12复合材料的关键。而SiC颗粒一及分布均匀性对力学性能有较大影响。此外,制备过程不慎造成财元素残留在材料内会降低其力学性能。 相似文献
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基于试验设计法的L形薄板弯曲回弹预测 总被引:1,自引:0,他引:1
用正交试验设计法和均匀试验设计法对L形薄板弯曲回弹进行预测。借助两种试验设计方法进行方案试验,利用ANSYS/LS-DYNA数值模拟得出各组方案中不同因素组合下的回弹量;通过直观分析、方差分析、回归分析和假设检验,得到各因素对回弹角的影响,找出取得最小回弹量的各因素水平的最优组合,获得试验范围内影响回弹的最佳工艺范围。结果表明,均匀试验设计法能够对回弹进行更有效的预测和控制。 相似文献
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混粉工艺对纳米Al2O3弥散强化铜基复合材料摩擦学特性的影响 总被引:1,自引:1,他引:1
以纳米A l2O3为增强相,用粉末冶金法制备了弥散强化铜基复合材料,研究了混粉工艺对复合材料滑动摩擦学特性的影响。结果表明:添加纳米A l2O3的复合材料其摩擦因数均有不同程度的减小,但以纳米A l2O3质量分数为5%及采用表面活性剂对粉体处理后得到的复合材料的摩擦学性能最好,平均摩擦因数下降近50%,平均磨痕深度下降了40%。对纳米粉体进行分散,可有效解决纳米粉体的软团聚现象,继而得到组织均匀的弥散强化铜基复合材料,特别是在较大复合量的情况下,采用表面活性剂是获得良好摩擦学性能的必由之路。 相似文献
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《Tribology - Materials, Surfaces & Interfaces》2013,7(3):139-145
AbstractLow carbon steel surfaces were alloyed with composite powders using the tungsten inert gas welding method. After the alloying process, the effects of cladding surface on the microstructural characteristics and adhesive wear of the alloyed samples were examined. The sliding wear behavior of samples was investigated in a block on ring apparatus under the loads of 20, 40, 60 and 80 N respectively. In the experimental investigation, a low carbon steel surface was alloyed with austenitic stainless steel powder and austenitic stainless steel powder mixed with 4·5% Co, Mo and Ti particles respectively. Following surface alloying, conventional characterisation techniques, such as optical microscopy, scanning electron microscopy, energy dispersive spectrograph and X-ray diffraction, were used to study the microstructure of the alloyed zone. Examination of the microstructure revealed the presence of M23C6 carbides, solid melt phases and intermetallic phases, such as Ni3Ti, depending on the alloying element in the composite. As the amount of the reinforcing material increased, the saturation rates for the samples decreased, while their hardness increased. The adhesive abrasion tests conducted revealed that temperature input plays a significant role on the microstructure characteristics, which positively affected the adhesive abrasion values of the samples. Consequently, the tungsten inert gas welding method was successfully used for the surface alloying of low carbon steels. 相似文献
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Optimization of brazing conditions for OFHC Cu and ASTM A501 low carbon steel by taguchi method 总被引:1,自引:0,他引:1
Yi Qi Wang Ali Md. Afsar Jung Il Song 《International Journal of Precision Engineering and Manufacturing》2009,10(3):97-104
This paper concerns the optimization of brazing conditions for joining the two dissimilar materials Oxygen-free high conductivity
(OFHC) copper and ASTM A501 low carbon steel usually used for an Oil-Separator of an air-conditioner using Ag-based (BAg)
alloy as a brazing filler metal (BFM). A mixture of 70% N2 and 30% H2 gases was used to prevent oxidation of the joints during furnace brazing process. Brazing joint clearance, length, temperature,
and time were selected as design parameters that have significant effect on the bonding strength of a brazed joint. Taguchi
method was used as a statistical technique for design of experiment (DOE) in an attempt to optimize brazing conditions in
terms of shear strength. L9 (34) orthogonal array was designed for conducting the experiments. The relative influence of design parameters and their interaction
on the response were also discussed. The experimental results verified that the brazing conditions predicted in this study
by Taguchi method could produce the brazed joint between OFHC copper and ASTM A501 low carbon steel with maximum shear strength. 相似文献
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Thiago Henrique Scarabello Stape Murilo De Sousa Menezes Bruno De Castro Ferreira Barreto Lucas Zago Naves Flávio Henrique Baggio Aguiar Paulo Sérgio Quagliatto Luís Roberto Marcondes Martins 《Microscopy research and technique》2013,76(8):788-794
This study focused on adhesive interface morphologic characterization and nanoleakage expression of resin cements bonded to human dentin pretreated with 1% chlorhexidine (CHX). Thirty‐two non‐carious human third molars were ground flat to expose superficial dentin. Resin composite blocks were luted to the exposed dentin using one conventional (RelyX ARC) and one self‐adhesive resin cement (RelyX U100), with/without CHX pretreatment. Four groups (n = 8) were obtained: control groups (ARC and U100); experimental groups (ARC/CHX and U100/CHX) were pretreated with 1% CHX prior to the luting process. After storage in water for 24 h, the bonded teeth were sectioned into 0.9 × 0.9 mm2 sticks producing a minimum of 12 sticks per tooth. Four sticks from each tooth were prepared for hybrid layer evaluation by scanning electron microscope analysis. The remaining sticks were immersed in silver nitrate for 24 h for either nanoleakage evaluation along the bonded interfaces or after rupture. Nanoleakage samples were carbon coated and examined using backscattered electron mode. Well‐established hybrid layers were observed in the groups luted with RelyX ARC. Nanoleakage evaluation revealed increase nanoleakage in groups treated with CHX for both resin cements. Group U100/CHX exhibited the most pronouncing nanoleakage expression along with porous zones adjacent to the CHX pretreated dentin. The results suggest a possible incompatibility between CHX and RelyX U100 that raises the concern that the use of CHX with self‐adhesive cements may adversely affect resin‐dentin bond. Microsc. Res. Tech. 76:788–794, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
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Bronze-uncoated and nickel-coated graphite composites were fabricated by powder metallurgy route. The tribological behaviors of composites sliding against AISI52100 steel ball under dry sliding condition were studied using a ball-on-disk tribometer. The nickel-coated graphite composites showed much better tribological properties in comparison with bronze and uncoated graphite composite. The friction coefficient of nickel-coated graphite composites decreased with increasing nickel-coated graphite content. However, the specific wear rate increased with the increase in nickel-coated graphite. The composite containing 15?wt% nickel-coated graphite showed the best self-lubricating properties because the compacted and stable mechanical mixed layer was formed on the worn surfaces. The wear mechanism of bronze 663 is adhesive wear and abrasive wear. The uncoated nickel-coated graphite composite shows the adhesive wear and delamination characteristics. However, the wear mechanism of nickel-coated composites is mildly abrasive wear. 相似文献
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为研究不同铜含量的浸金属碳滑块的载流摩擦磨损性能,在环-块试验机上研究3种不同铜含量(铜质量分数分别为1.17%、27.8%、50.45%)浸金属碳滑板与铜银合金接触线在载流条件下的摩擦磨损性能,并比较不同电流情况下的材料磨损表面形貌的变化。结果表明:铜含量对浸金属碳碳滑板的摩擦磨损性能有不同的影响。其中铜质量分数为1.17%的材料在200 A小电流情况下整体磨耗量较小,但是在400 A大电流情况下,电弧热、焦耳热产生的500℃左右高温会导致材料气化、掉块,严重加剧材料的损耗;铜质量分数为50.45%的材料在小电流情况下磨耗最大,但材料的运行温度整体较低,即材料的散热性能较好;铜质量分数为27.8%的材料在小电流与大电流情况下综合磨损性能最好。与铜银合金线对磨时,铜含量较高的材料出现了较为明显的黏着磨损,铜含量越高的材料其黏着磨损现象越明显。 相似文献
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V. A. Kovtun V. N. Pasovets M. Mikhovsky A. I. Kharlamov 《Journal of Friction and Wear》2010,31(2):128-132
The problem of using onion carbon structures in the development of highly wear-resistant powder composite materials on a copper matrix base is discussed. Study results are presented of the triboengineering and physicomechanical properties of composite materials with a nanostructured filler. Reduction of the wear rate of the composites with copper and onion carbon nanostructures is attributed to decreased metal contact area on the friction surface and inhibited seizure. 相似文献
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尼龙6/铜复合粉末选区激光烧结工艺参数优化及力学性能研究 总被引:1,自引:1,他引:0
制备了不同铜粉含量(质量分数)的尼龙6机械混合复合粉末,对复合粉末进行激光烧结,利用扫描电镜对烧结件的形貌进行了表征,通过正交试验优化工艺参数,并研究了铜粉含量对烧结件力学性能的影响。结果表明,铜粉与尼龙表面黏结良好,铜粉均匀分布在尼龙基体中;随着铜粉含量增加,烧结件抗弯强度、抗拉强度显著提高,冲击强度逐渐降低;铜粉含量为50%时,烧结试样抗拉强度为43.28MPa,抗弯强度为77.66MPa,硬度为112HRL,分别比纯尼龙6提高了10.04%、59.27%和39.29%。 相似文献
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为满足电子仿生皮肤的穿戴舒适度,提出了一种电容式柔性织物压力传感器,采用丝网印刷工艺,以织物为柔性基体,炭黑填充型复合弹性电介质和有机硅导电银胶制备柔性压敏触觉单元。介绍了压敏单元的结构设计与感知机理,研究了炭黑含量与温度对织物触觉单元性能的影响,改善了该电子织物的输出线性度与重复性,实现了0~700 k Pa量程范围迟滞误差为5.6%,动态响应时间为89 ms,灵敏度为0.025 36%/KPa,同时,引入温度补偿以提升触觉感知准确性。通过将织物压敏单元应用于足底压力信息的时空分布研究和机械手的软抓取实验,其足底压力分布及触觉感知实验结果表明,该电容式柔性织物压力传感器具有良好的工作稳定性与触觉感知功能,为可穿戴式人工皮肤的研究提供了一种设计方案。 相似文献