粉体在机械振动筛中静电起电的试验

可燃粉料在机械振动筛中的振动往往会导致粉尘爆炸事故的发生，其引燃源除了机械振动产生的摩擦、冲击、热表面等因素以外，静电放电火花是一个重要原因，本文对金属类粉体和如镁粉、粮食类粉体如麦芽粉在工业规律的机械振动筛筛分时产生的静电带电量进行了试验测试。结果表明：无论是导电的金属粉体还是非导电的粮食粉体产生的静电业已超出《静电安全导则》的界限，对于引燃能量较低，爆炸猛烈度较大的粉体，采取防静电措施是必要的。     

关于消除静电系统探讨与实践

静电放电是电能转换成热能的过程,放电过程中一旦周围有可燃性气体,将有可能引燃气体,产生爆炸。启动燃料站内存储液化天然气(LNG)和气化天然气(CNG),需要对该站消除静电系统进行检测与完善,确保安全生产。     

用于空调换热表面处理的憎水性石墨烯复合塑料的研究

塑料由于廉价、质轻等特性,广泛应用于各个领域,但塑料制品在加工和使用过程中容易因摩擦等产生静电,不仅引起塑料表面吸尘影响美观,甚至产生静电火花而引起爆炸或火灾。采用石墨烯为添加导电剂解决其与聚碳酸酯(PC)基体间的亲和力问题;解决塑料固有的静电问题,同时提高塑料的导热、耐磨、抗老化等性能;采用液相复合法、熔融法两种工艺将石墨烯分散到塑料聚碳酸酯基体中,实现了用于对空调换热表面进行憎水性处理的石墨烯复合塑料制品的制备。     

导电二氧化钛粉末的研究进展

1前言高分子材料具有优良的电绝缘性能，因而广泛地应用于工农业生产和生活的各个领域．但是，由于一般高分子材料的高电国率，其制品受物流的摩擦、把市易产生静电．静电聚集到一定程度就会引起放电．甚至可能引起击穿或火灾，也会对无线电接收机产生强烈干扰，使雷达无法正常工作．因此，防止产生静电和消除静电就是一件十分重要的事情．如果能在高分子材料中掺入导电微粒，使之具备一定的传导电流和消散电荷的能力，通过接地就可消除静电引起的聚积电荷，从而消除和防止了静电带来的危害．目前，常用的导电粉末包括金属系粉末（如铜粉、…     

2021年中国有色金属粉体-铜基金属粉体行业市场规模及上下游市场分析北大核心

铜具有优良的导电、导热、耐蚀、易加工等特性,是国民经济的重要基础材料。目前,国内铜基粉体材料多数应用于粉末冶金零部件、超硬工具、高铁动车组闸片等领域,随着制备技术的逐步完善以及产品质量的进一步提高,铜基金属粉体材料已被广泛应用于更丰富的领域,如导电浆料、化工催化剂等。     

石墨烯增强WC-Co硬质合金的制备和力学性能研究

采用机械搅拌和静电吸附工艺制备了氧化石墨烯/WC-Co复合粉体,并对复合粉体的微观形貌进行了表征。利用放电等离子烧结(spark plasma sintering,SPS)技术制备了石墨烯/WCCo硬质合金,对复合材料的力学性能进行了测试分析。机械搅拌制备的氧化石墨烯/WC-Co复合粉体经过SPS烧结后得到的硬质合金横向断裂强度和维氏硬度为1 850 MPa,1 830,与不添加石墨烯的WC-Co硬质合金相比分别提高了3.9%,5.8%。静电吸附制备的氧化石墨烯/WC-Co复合粉体经过SPS烧结后得到的硬质合金横向断裂强度和维氏硬度为1 980 MPa,1 850,与不添加石墨烯的WC-Co硬质合金相比分别提高了11.2%,6.9%。     

爆炸冲击在新材料中的应用与进展

爆炸冲击具有作用力大 ,产生温度高及作用时间短等特点 ,因此在新材料的开发中有不可替代的潜在优势与前景 ,综合分析了爆炸冲击在粉体处理、合成超硬材料、合成纳米晶粒和爆炸烧结等领域应用前景及研究进展。     

填料用高岭土深度加工新工艺

高岭土粉体是塑料和橡胶制品的重要填料,以往国内的高岭土粉体加工只限于一般的碾磨机械粉碎,难以使高岭土粉体细度提高。近年来通过对高岭土粉体进行超音速气流粉碎,使高岭土粉体细度大幅度提高,如     

碳纳米管增强铝基复合材料的制备及力学性能研究

利用静电自组装和机械搅拌法相结合的工艺制备得到碳纳米管/铝(carbon nanotubes/aluminum,CNTs/Al)复合材料粉体并压坯制成预制块.采用搅拌铸造和热轧相结合的工艺制备得到不同碳纳米管(carbon nanotubes,CNTs)含量的CNTs/Al复合材料.通过扫描电子显微镜(scanning...     

烧结用振动筛振动器结构的发展概况

筛分机械是造块工艺不可缺少的设备之一,特别是近年来烧结矿整粒技术的发展,筛分机械在造块工艺中的应用更加广泛。惯性振动筛(本文简称振动筛)具有工艺效果好,结构简单,操作维修方便等优点,因此现代造块工艺所应用的筛分机械几乎都是振动筛。共振筛由于结构复杂、机重大、难调整,特别是筛上负荷变化时,难于     

Comparison Between Ultrasonic Vibration-Assisted Upsetting and Conventional Upsetting

Ultrasonic vibration has been increasingly applied to metal forming processes due to its beneficial effects on the reduction of the forming force, flow stress, and friction coefficient and on the increase of the forming limit of the sheet metal. In this work, the effect of the ultrasonic vibration on the upsetting has been studied experimentally and numerically. The microstructure of the specimens processed with ultrasonic vibration-assisted upsetting (UAU) and conventional upsetting was characterized. Differences in the forming characteristics between these two methods, in terms of metal flow and forming force, were analyzed. The results of this study indicate that the use of high-intensity ultrasonic vibration can induce severe plastic deformation and improve the grain refinement efficiency. The grains of the specimens processed by the UAU process were refined to 100 to 300 nm. A deformation mechanism of the UAU process was proposed. The grain refinement mechanism was used to explain the reason why ultrasonic vibration can be used to improve the grain refinement efficiency of the upsetting process.     

振动球磨制备Fe-6.5 %Si硅钢微粉

采用振动球磨法制备Fe-6．5％Si（质量分数）硅钢微粉，试验中对硅钢粉末进行不同球料比、不同球磨时间、干法球磨和湿法球磨制备微粉试验。结果表明：随着球磨时间的延长，颗粒尺寸变细，球磨12h后，颗粒细化速度变慢；加大球料比及延长球磨时间可进一步细化粉末粒度，但对粉末的粒度分布无影响；湿磨比干磨制粉效率高，粒度分布多在小粒级范围内。     

冶金用耐火材料与铁水相际间运动的电现象

钢铁冶炼过程中,耐火材料与钢液(铁水)界面间存在的电场将影响两相间的润湿、溶解以及化学反应等界面作用.为明确钢液(铁水)与耐火材料间因相对运动所引起的摩擦起电行为,进行低温流体流动带电试验和热态模拟试验.由低温流体流动带电试验可知,随着搅拌速度的增加,流体与石墨容器因摩擦起电所产生的静电电压逐渐增大;不同种类的流体因其...     

Mathematical Model of the Melt Impregnation of Metal Powder Using Vibration Treatment

A model of the melt impregnation of metal powder under low-frequency vibration is presented in the form of mathematical dependences. The influence of factors such as the powder dispersity, its wetting with the melt, melt viscosity, and conditions and parameters of the vibration treatment are considered. The results of simulation are confirmed by the experimental data found using vibration treatment and without it. Recommendations on the selection of amplitude-frequency parameters are elaborated.     

Gas-Sprayed Tin Powders

A gas-dynamic technology has been developed for obtaining tin powder by spraying molten metal and equipment has been built for this purpose. The powder (grain size <100 m) is distinguished by the stability of its parameters, including the granulometric composition. This is achieved by keeping the technological parameters stable throughout the metal spraying process. Those parameters have been calculated and then refined on the basis of results obtained from experimental research on the process of spraying liquid metal. A constant molten metal consumption is ensured by a special dosing device. Its design and operation are described and the parameters of the powders produced are given.     

WC粉末粒度与形貌对硬质合金中WC晶粒度、晶粒形貌与合金性能的影响

探讨了粗颗粒与特粗颗粒两种粒度级别以及平面化表面与球化表面两种形貌特征的WC原料对WC-Co硬质合金中WC晶粒度、晶粒形貌以及合金性能的影响。结果表明,分别采用费氏粒度为11.4￣13.4μm,与22.0￣28.3μm两种粒度级别的WC粉末为原料制备合金,尽管两种合金硬度之间存在明显差别,但是两种合金的晶粒度相差很小,在4.0￣4.3μm之间,同属一种粒度级别。WC原料的原始形貌对合金中WC晶粒形貌与合金性能影响很小,碱金属掺杂原料制备的合金中WC晶粒结晶完整性相对较差。因此,高纯原料是制备高性能硬质合金的基础。     

DETERMINATION OF STATIC AND FATIGUE COMPRESSIVE STRENGTH OF HARD-METALS

Abstract

Procedures for the assessment of the very high static and fatigue compressive strength of hard-metals are briefly reviewed. A test-piece with enlarged ends has been developed. Using this, stress/strain curves and fatigue–strength data have been obtained on WC–Co hard-metals with various cobalt contents and carbide grain sizes. The results can be rationalized by being plotted against the mean free path in the binder metal.     

多孔金属材料制备工艺及展望

本文介绍了多孔金属材料现阶段的发展状况、常用制备工艺及功能应用,并对多孔金属材料的发展趋势进行了展望。制备方法主要是从熔体、粉末、沉积几方面展开概述,再对各种工艺的制备原理、优缺点、孔隙率和金属材料进行了综述,并列举了近年国际、国内采用新型发泡剂和造孔剂对多孔金属的研究状况和成果。多孔金属材料既可以用于结构材料也可以用于功能材料,在减振、吸能及轻量化方面有着广阔的应用前景。     

超声雾化Sn-Pb焊锡粉的组织特征及其抗氧化性能

采用定氧仪、扫描电镜和俄歇表面谱仪研究了超声雾化制备的Sn-Pb焊粉的氧化速率、组织与形貌特征，并与离心雾化焊粉进行了对比。结果表明：超声雾化法制备的粉末形貌和球形度明显优于离心雾化，但在大气中放置粉末的增氧速度较快。显微组织对比发现超声雾化制备的粉末组织晶粒细小、两相分布更加均匀；俄歇分析表明超声雾化粉末表面Pb出现一定程度的富集；高频振动和快冷促进了粉末组织的细化，表面富铅、晶界和相界数量增加是造成焊锡粉室温抗氧化性不足的主要原因。     

Serrated grain boundary formation potential of Ni-based superalloys and its implications

The serrated grain boundary formation potential of a large number of conventionally forged, powder processed, and investment cast Ni-based superalloys is reviewed. A mechanism of serrated grain boundary formation by which grain boundaryγ′ particles move and displace the local grain boundary segment is discussed and the prerequisite conditions for its occurrence are highlighted. The practical implications of the serrated grain boundary formation are also discussed. It is suggested that modifying the existing heat-treatment cycles in some investment cast and powder processed Ni-based superalloys would improve their properties. The possibility of minimizing weld cracking in superalloys by creating serrated grain boundaries in the base metal and the heat affected zone is also discussed.