共查询到20条相似文献,搜索用时 15 毫秒
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Ru-Ti-Ir-Sn氧化物涂层阳极的研究 总被引:8,自引:1,他引:7
采用热分解法制备了不同组分的Ru Ti Ir Sn氧化物涂层阳极 ,从涂层的电化学性能测试和物理性能分析得出 :添加Ir、Sn氧化物 ,虽然提高了电极的耐氧腐蚀 ,但降低了电极的析氯催化活性 ,阳极涂层表面形貌疏松 ,涂层中含有较多的TiO2 (A)相和α Ti相 ,是导致阳极析氯电位升高的主要原因 相似文献
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羟基磷灰石涂层人工关节应用研究 总被引:3,自引:0,他引:3
对羟基磷灰石的成骨效应进行了研究,对添加骨水泥不当而导致的羟基磷灰石涂层人工关节涂层脱落进行了分析。结果表明,对于羟基磷灰石涂层人工关节,应有涂层区和非涂层区,骨水泥只能在非涂层区填充,而在涂层区则应使羟基磷灰石涂层直接与骨组织接触。这种人工关节,不仅充分利用了羟基磷灰石良好的生物相容性和成骨效应,而且有利于手术后的短期机械固定和长期的生物固定。 相似文献
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高W型Ni基高温合金M963中碳化物研究 总被引:2,自引:0,他引:2
研究了一种高W,Mo的Ni基高温合金M963中碳化物的种类、形态、分布及产生的相关工艺条件和形成机理.实验研究发现,根据碳化物产生的热力学条件不同,可以把M963合金中出现的碳化物分为:遗传型碳化物、自发形核型碳化物和析出型碳化物三类.未熔体处理的合金组织中以粗大的块状遗传型MC碳化物为主,遗传型碳化物多分布于晶界和枝晶间.经过熔体处理后,合金中开始出现自发形核的共晶型汉字碳化物,在更高的熔体处理温度1850℃以上,出现了自发形核的非共晶型颗粒碳化物,自发形核碳化物多分布于枝晶间.随熔体处理温度的升高,碳化物形态的变化顺序为:块状→汉字形→颗粒状,碳化物的尺寸变小,分布更加均匀. 相似文献
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Resin lens are very popular in glasses market. Many technologies have been developed to coat different thin films on resin lens to strengthen its resistance to scratch or wear, but little of the scratch failure mechanism of such thin films are reported. This paper presented the results of several scratch tests performed on three resin lenses coated with different thin films at the normal loads of 98 mN and 49 mN and at sliding velocity of 0.003 3 m/s and 0.001 7 m/s, and the observation of the scratch tracks on the resin lens by SEM. It shows that the resin lenses coated with different thin films have different scratch resistance and different scratch failure mechanism, and the scratch resistance varies at the two different loads and sliding velocity. The experiment provides a new method to evaluate the scratch resistance of resin lens. 相似文献
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Duplex microstructures of iron-base superalloys, consisting of an austenitic matrix and a M7C3 carbide, can be produced within the Fe-Mn-Cr-Mo-Al (Si)-C systems. The stability regions of the carbides were inspected by means of isothermal sections of alloys in the quinary combination Fe-Mn-Cr-Mo-C for 70 at% metal and 30 at % carbon. For 35 at % iron the competing carbides are found to be M2C, M3C and the molybdenum cementite (MoFe2C) in the arc-melted state, with M23C6 in the annealed state. In the quaternary system, Fe-Mn-Mo-C, a M2C carbide forms, presumaby derived from a solid solution carbide, (Mn, Mo)2C. In extracted carbides of cast alloys containing Fe-Mn-Cr-Mo-Al (Si)-C a considerable amount of the -phase carbide occurs. 相似文献
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《Materials Science & Technology》2013,29(2):100-104
AbstractEstimates are made of the cohesive energies of the group VA transition metal carbides for various C contents and crystal structures. In the cubic structure MCx, several factors help to provide optimal cohesion at x < 1, even in the presence of excess C. Notable among these is a drop in the Fermi level when vacancies appear in the C sublattice. A strong C–C repulsion between very close neighbours prevents the hexagonal structure becoming stable when x is large, even though the underlying metal sub lattice is expected to prefer hcp to fcc at these electron concentrations. In M2 C the C–C repulsive contribution is sufficiently reduced to allow the hexagonal structure to appear. The opportunity for afurther reduction in this repulsive contribution, together with a change in electrostatic energy, provides a strong tendency for ordering in the C sub lattice of M2 C, leading to high ordering temperatures.MST/3031 相似文献
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碳化钼的制备与表征 总被引:12,自引:0,他引:12
以MoO3为前体, CH4/H2为还原碳化气, 经程序升温还原碳化反应制备了Mo2C样品, 并用TG-DTA、XRD、BET、SEM、XPS进行了表征. 结果表明, MoO3在CH4/H2气氛中的还原碳化历程为MoO3→MoO2→MoOxCy→Mo2C, 适宜的还原碳化温度为675℃. 实验条件下制得的碳化钼晶相为β-Mo2C, 表面呈现出形状规整、大小相对均一的片状颗粒, 平均粒径约3.9μm. 碳化钼表面有两种不同价态的钼原子, 分别归属于Mo--C 物种的Mo2+和Mo--O物种的Moδ+ , 以前者为主; 碳物种由四种不同价态的碳原子组成, 分别归属于C--Mo、C--C、C--H和C--O物种, 以前者为主. 随还原碳化反应温度的升高, 制备的碳化钼颗粒增大, 比表面积下降, C--C物种和C--H物种增加, 表面积炭增多. 由于积炭的覆盖和保护作用, 碳化钼表面的Mo原子主要以Mo2+ 的Mo--C物种存在, 只有少部分被氧钝化. 相似文献
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纳米WC硬质合金制备新工艺 总被引:16,自引:0,他引:16
文章综述了制备纳米WC、WC Co粉体的几种方法。着重阐述了纳米WC Co硬质合金的烧结新工艺 :微波烧结、二阶段烧结、快速热等静压烧结和等离子体活化烧结等。与传统烧结方法相比 ,使用这些烧结新工艺制备的产品性能更优异 ,有很大的发展前景。 相似文献
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除湿换热器可以同时处理显热与潜热负荷,但由于吸附热的影响,存在热湿负荷处理不同步及显热负荷处理能力不足的问题。本文提出了在除湿换热器后面串联一个显热换热器对空气进行二次处理,搭建了实验台对除湿换热器串联换热器情况下除湿降温过程的动态性能进行测试,并且在实验中分析了水温、进风温度、湿度、速度等主要参数对除湿量、降温量、制冷功率、COP的影响。结果表明:增加显热换热器可以大幅度增加处理空气的平均降温温差,在除湿初期阶段效果尤为明显,同时系统的制冷量也明显提高。此外,分析各参数对实验结果的影响可知,冷水温度与热水温度升高都可以有效提高系统制冷量与COP,空气的温湿度升高会提升系统性能,空气流速变慢对系统平均除湿量与有效除湿时间有明显的提升。 相似文献
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干燥剂涂层换热器(DCHE)是一种新开发的翅片管表面带有干燥剂涂层的换热器,它可以同时处理潜热和显热.为了获得更高的性能,高孔隙度的金属有机框架(MOF)被引入到设计中.本文通过水浴法成功合成MIL-101(Cr)材料,并对材料进行X射线衍射(XRD)、N2吸附-脱附测试、水蒸气吸脱附曲线、电镜扫描等系列物理表征.制作... 相似文献
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利用SiH4(80%Ar稀释)和CH4作为源气体,通过改变源气体流量比、基片温度、沉积气压等参量,使用微波电子回旋共振化学气相沉积法生长非晶碳化硅薄膜。实验结果表明碳化硅薄膜沉积速率随气体流量比R(CH4/(CH4+SiH4))的增加而减小、随基片温度的升高明显减小、随沉积气压的增加先增大后减小。红外结构表明:在较低流量比R下,薄膜主要由硅团簇和非晶碳化硅两相组成,而当R>0.5时,薄膜的结构主要由非晶碳化硅组成,薄膜中键合的H主要是Si和C的封端原子。同时,沉积温度的升高使碳化硅薄膜中Si-H,C-C和C-H键的含量减少,而薄膜中Si-C含量明显增加且峰位发生了红移。薄膜相结构的转变是薄膜光学带隙变化的原因。 相似文献
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铌钒微合金钢中碳化物的析出过程 总被引:2,自引:0,他引:2
为了解铌钒微合金钢碳化物析出过程对机械性能的影响,将Nb-V微合金钢在1200℃固溶0.5h后淬火,在500℃回火不同时间,淬火样品的显微硬度最高,随着回火时间延长,显微硬度先快速下降,随后上升,在回火4~10h时出现一个硬度峰,随后又缓慢下降.用三维原子探针(3DAP)研究这些样品中碳化物的析出特征.结果显示,淬火样品中V、Nb元素分布均匀;随着回火时间延长,碳化物的尺寸逐渐增大,数量增加,回火4~10h的样品数达到最多,与硬度峰对应,同时V碳化物依次向V、Nb和V、Nb、Mo的复合碳化物转变. 相似文献
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Cemented carbides are mainly used as cutting tools in various fields of application. In nearly all industrial uses they have to resist wear and concurrent complex thermomechanical loading, often including alternating mechanical loads at high temperatures. It has been shown that cemented carbides suffer lifetime‐limiting fatigue under cyclic loads at 25 °C caused by subcritical crack growth. Present investigations show that strong, temperature‐dependent fatigue effects occur in cemented carbides at elevated temperatures. TEM investigations revealed temperature‐dependent processes that are responsible for the changes in the fatigue behavior: at low temperatures a phase transformation of the Co‐binder phase and at higher temperatures oxidation in the cracks and brittle–ductile transitions of cubic carbides. 相似文献