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通过采用金属热压模具及其对应的热压工艺制造出的锯片,与采用石墨热压模具及其对应的热压工艺制造出的锯片,进行锯切混凝土对比试验,并对锯片工作面的金刚石状态进行测量。结果表明,用金属热压模具制造出的锯片的性能不比用石墨热压模具制造出来的锯片的性能差,其烧结温度可降低60℃,原因是前者胎体包镶金刚石的能力比后者强,且热压工艺中对金刚石的损伤比后者少。这将能充分发挥金属材料抗氧化性强、低温强度高的优势,从而使金属材料能应用于金刚石锯片热压模具。金属热压模具替代石墨热压模具制造特殊锯片齿时,单齿热压模具成本更低,精度更高。 相似文献
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通过试验和分析,说明在中频热压烧结金刚石钻头过程中,钻头性能受各种因素综合影响,其主要因素是电磁场影响到胎体粉料和金刚石分布,模具配合间隙引起胎体的流失而导致金刚石浓度发生变化。文中分析了电磁场对钻头性能的影响与胎体中铁磁物质含量及金刚石浓度的关系,也分析了模具配合间隙对胎体流失而引起金刚石浓度变化的关系。在中频热压烧结,高铁磁质含量胎体和低金刚石浓度的前题下,采用新工艺制作钻头,金刚石分布得到改善,钻头在使用中取得了良好的效果。 相似文献
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在热压烧结法制造金刚石钻头的过程中,胎体配方和烧结工艺是直接决定金刚石钻头性能的两个关键因素。为了提高钻头的钻进效果并降低钻头成本,采用高铬铁合金粉和镍铁合金粉替代WC粉作为金刚石钻头的胎体配方材料。热压金刚石钻头的烧结参数主要包括烧结温度、保温时间、烧结压力和加压方式,其中保温时间的长短直接关系热压金刚石钻头的性能。文章主要讨论保温时间对Fe基金刚石钻头性能的影响。选用新的Fe基配方,以保温时间为变量,其余参数保持不变,装料并烧结一组此参数下的样品。通过对这些样品的弯曲、拉伸、压缩、硬度等力学性能测试以及断口扫描电镜分析,最终得出此配方下的最优保温时间。 相似文献
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介绍国内目前最先进的几种新型地质、石油金刚石钻头。对新型金刚石钻头的设计理念、制造工艺及特征进行简述,为金刚石钻头设计制造提供参考。 相似文献
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介绍了硬岩深孔钻进中热压金刚石钻头的设计方法与研制技术,重点就钻头胎体的设计研究方法进行了较全面的分析与阐述,对钻头的结构设计作了深入的研究与探讨,为读者研究金刚石钻头提供了思路与方法。论文以科钻一井为例,在分析岩石性质与钻进条件的前提下,对硬岩、深孔、大口径取芯金刚石钻头的设计作了具体的论述,钻头的保径措施和工作层结构采用了全新的设计方案;热压工艺完全不同于普通钻头的传统烧结规程,钻头质量在科钻一井使用的各类钻头中取得了平均时效(1.12m/h)和平均寿命(28.85m/个)最好的效果。钻进事实表明,胎体的设计研究方法是一种先进的具有普遍意义的方法;钻头的结构设计和保径措施.同样具有创新性和实用价值. 相似文献
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Chemical and morphological heterogeneities of carbon sorbents play important roles in gas-phase adsorption. However, the specific chemical complexes and topological structures of carbon that favor or impede elemental mercury uptake are not well understood and are the subject of this study. Temperature programmed desorption (TPD) with a model carbonaceous material (highly oriented pyrolytic graphite, HOPG) under ultrahigh vacuum (UHV) conditions and fixed bed adsorption by activated carbon (BPL) at atmospheric pressure were combined to investigate the effects of chemical and morphological heterogeneities on mercury adsorption by carbonaceous surfaces. TPD results show that mercury adsorption at 100 K onto HOPG surfaces with and without chemical functional groups and topological heterogeneity created by plasma oxidation occurs through physisorption. The removal of chemical functionalities from the HOPG surface enhances mercury physisorption. Plasma-oxidation of HOPG provides additional surface area for mercury adsorption. However, the pits created by plasma oxidation are more than 10 nm in diameter and do not simulate microporosity that predominates in activated carbons. Mercury adsorption by activated carbon at atmospheric pressure occurs through two distinct mechanisms. Physisorption governs mercury adsorption at lower temperatures (i.e., below 348 K), while chemisorption predominates at high adsorption temperatures (i.e., above 348 K). Presence of water on activated carbon surface enhances mercury uptake by both physisorption and chemisorption. Oxygen containing functional groups reduce mercury uptake by physisorption by blocking access to the micropores. No significant impact of oxygen functionalities was observed in the chemisorption regime. The key findings of this study open the possibility to apply scientific information obtained from the studies with simple surfaces such as HOPG under ideal conditions (UHV) to industrial sorbents under realistic process conditions. 相似文献
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Pernilla Johansson Kristina Mjörnell Jesper Arfvidsson 《Holz als Roh- und Werkstoff》2017,75(4):603-613
Building materials differ in their susceptibility to mould growth. Wood is a material often considered to have a low mould resistance. However, wood is not a homogenous material and different characteristics of the material are expected to have an impact on mould growth. In this paper, it was shown that wood species (pine or spruce), sawing pattern (centre-board or side-board) and surface structure (planed or sawn) affected mould growth. In addition, it was indicated that the susceptibility cannot be described by one single parameter, but also depends on other parameters. It is therefore difficult to estimate the susceptibility of wood in general. These conclusions were drawn from a meta-analysis, using data from five separate, previously performed laboratory studies conducted at 90% relative humidity and 22 °C, and from a laboratory study performed at 95% RH and 22 °C. 相似文献
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采用高温空气氧化法对碳纤维表面进行改性处理,同时采用磷酸氧化法对芳纶短切纤维表面进行处理,对改性前后的两种纤维分别进行表征;采用芳纶浆粕、竹浆、海泡石绒以及改性前后的碳纤维和芳纶短切纤维混合来抄造纸基摩擦材料原纸;探究纤维的表面改性处理对纸基摩擦材料原纸强度性能的影响。结果表明,改性后的纤维表面产生了很多沟壑,纤维表面粗糙程度增加,纤维表面的接触点和面积更多,结合力更大,同时引入了大量的活性基团;用改性纤维配抄的纸张层间结合强度比未改性纤维配抄的纸张层间结合强度提高了21%。 相似文献
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随着电磁波的广泛应用,电磁污染已成为除空气、水、噪声污染外的第4类污染,故电磁防护非常重要。电磁防护材料主要分为吸波材料和屏蔽材料,吸波材料以损耗为主使电磁波衰减,屏蔽材料以反射、吸收和多次内反射等方式使电磁波衰减。碳系材料以其优良的导电性在电磁屏蔽家族中扮演着重要的角色,碳系材料包括石墨、膨胀石墨、石墨纳米片、碳纳米管和石墨烯等。碳系屏蔽材料可作为导电填料,提高聚合物的导电性。通过晶格掺杂可使碳晶格中产生更多缺陷,导电性提高,从而提高屏蔽效能。碳系屏蔽材料与其他材料复合可通过提高导电性或增加磁损耗,使屏蔽效能增加。将碳系屏蔽材料通过浸润或涂覆的方式负载到织物上,可制备电磁屏蔽织物。本文针对碳系屏蔽材料的现状进行综述,简要介绍了碳系屏蔽材料的制备方法,重点阐述了其通过晶格掺杂和材料复合提高屏蔽性能,最后总结了其在纺织方面的应用。 相似文献
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在过去的10年中,碳纤维,或者石墨纤维、碳石墨纤维、CF,在许多应用中已经成为运动器材和飞机用的稳定、轻质材料。叙述了这种脆性纤维生产工艺中的难点及其解决方案。 相似文献
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抗液态锌腐蚀材料综述 总被引:10,自引:0,他引:10
阐述液态锌对金属的腐蚀机制 ,对耐液锌腐蚀的材料如石英玻璃、碳化硅、石墨、表面涂层材料及合金材料从多方面作了对比。指出SiC和合金材料是抗液态锌腐蚀的主要材料。利用表面改性技术 ,可在低成本基体上复合一层耐锌液腐蚀的合金层 ,可降低耐锌蚀材料成本 相似文献
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Zhao F Rahunen N Varcoe JR Chandra A Avignone-Rossa C Thumser AE Slade RC 《Environmental science & technology》2008,42(13):4971-4976
By employing the sulfate-reducing bacterium Desulfovibrio desulfuricans we demonstrate the possibility of electricity generation in a microbialfuel cell (MFC) with concomitant sulfate removal. This approach is based on an in situ anodic oxidative depletion of sulfide produced by D. desulfuricans. Three different electrode materials, graphite foil (GF), carbon fiber veil (CFV), and high surface area activated carbon cloth (ACC), were evaluated for sulfide electrochemical oxidation. In comparison to CFV and GF electrodes, ACC was a superior materialfor sulfide adsorption and oxidation and showed significant potential for harvesting energy from sulfate-rich solutions in the form of electricity. Sulfate (3.03 g dm(-3)) was removed from a bacterial suspension, which represented 99% removal. A maximum power density of 0.51 mW cm(-2) (normalized to geometric electrode area) was obtained with a one-chamber, air-breathing cathode and continuous flow MFC operated in batch mode at 22 degrees C. 相似文献