球磨时间和转速对球磨法制备纳米锑粉的影响

以250 μm大小的锑粉为原料,在添加相同含量蒸馏水和烷基酚聚氧乙烯醚的条件下,采用湿法机械球磨的方式制备出不同类型的锑基粉末.采用XRD、TEM及FT-IR对制备的锑基粉末的结构、形貌及粒径大小进行了表征分析,研究了球磨时间和球磨转速对锑粉制备的影响.结果表明:当锑粉原料中加入1 ml/g蒸馏水和0.2 ml/g OP-1O湿磨时,球磨转速为150r/min、球磨时间为18 h可制备出分散良好、粒径分布均匀、平均粒径约为10 nm的锑粉.     

钢表面激光熔覆Ti-Al球磨粉合成复合涂层

为提高钢的表面硬度及耐腐蚀性,选用钛,铝机械球磨粉末在Q235钢基体表面进行激光熔覆试验,使钛,铝发生反应并制备Ti-Al金属间化合物复合涂层. 综合运用DTA、XRD和SEM分析方法对激光熔覆涂层的成分与组织进行分析,并对复合涂层的硬度及耐腐蚀性进行测试. 结果表明,机械球磨可使粉体细化,涂层与基体形成了冶金结合,涂层由Al₃Ti,Al₃Fe,Fe,AlN和FeO组成,同时激光熔覆涂层具有较高的硬度及优良的耐腐蚀性能. 当激光功率为1000 W,扫描速度为600 mm/min时,复合涂层同时获得最高显微硬度和耐腐蚀阻抗值,分别为949.5 HV和600 kΩ.     

Phase transformation of nanocrystalline anatase powders during high energy planetary ball milling

1　INTRODUCTIONTitaniumdioxideisknowntoexistinthreecrys tallineformsofrutile ,anataseandbrookiteinnature .Rutileisthermodynamicallystablewhileanataseandbrookitecantransformirreversiblyandexothermicallytorutileoverarangeoftemperatures[1] .Inaddition ,therearetwohigh pressurephases ,srilankitewithorthorhombicstructureandTiO2 Ⅲ .Underhighpressure ,anataseandrutilecantransformtosri lankite[2 4 ] .Thesrilankitephasecantransformbacktorutileunderappropriateconditions[5] .Overthepastfew years …     

Deviation of a machined surface in flank milling

The flatness defects observed in flank milling with cutters of long series are mainly due to the tool deflections during the machining process. This article present the results of an identification procedure of the coefficients of a force model for a given tool workpiece couple for the prediction of the defects of the tool during the cutting. The calibration method proposed meets a double aim: to define an experimental protocol that takes the industrial constraints of time and cost into account and to work out a protocol which minimizes uncertainties likely to alter the interpretation of the results (environmental, software or mechanical uncertainties). For that, the procedure envisages the machining of a simple plane starting from a raw part formed by a tilted plane, allowing for the variation of the tool engagement conditions. The tool deviation during the cutting process is indirectly identified by measuring the machined surface. The observed straightness defect conditions can be explained by the evolution of the cutting pressures applied to the cutting edges in catch during the cutter rotation. The precision was considerably improved by the taking into account of the cutter slope defect in the calculation of the load applied to the tool. After identification of the tool-workpiece couple, the prediction model was applied to some examples and allowed to determine the variations of form and position of the surface points with a margin of 5%.     

Structures,properties and responses to heat treatment of deformation processed Cu-15% Cr composite powders prepared by mechanical milling

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Cu Al_2O_3 composite coating on AISI 1045 steel surface by laser cladding

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球磨表面包覆对镁基贮氢合金电化学性能的影响

表面包覆是一种表面改性方法,对于提高贮氢合金表面活性,防止氧化和抑制容量衰退有较积极的作用。探索了以球磨方法对二元非晶合金Mg50Ni50和三元非晶合金Mg(50-x)TixNi50(x=5,10,15)进行表面包覆的工艺及其对合金电极充放电循环稳定性的影响。结果表明：Y,Al,Ni等包覆元素皆可在一定程度上延缓非晶合金Mg50Ni50较快的循环容量衰退,而且Ni对Mg(50-x)TixNi50(x=5,10,15)合金的包覆可有效地提高其循环稳定性。     

淬火钢平面铣削工艺应用

介绍了对淬火钢平面铣削代替磨削的加工工艺。     

Laser assembly nanostructured Al2O3/TiO2 coating on cast aluminum surface

CO2 laser quick assembly technology is adopted on the surface of cast aluminum ZL104 to form a dense ceramic coating containing a great deal of nanometer Al2O3/TiO2 particles which eliminate cracks and porosities.The major phases of the coating are α-Al2O3 andβ-TiO2. The micro-hardness distribution of the coating is 1 813,1 504, 1 485 and 1 232 (HV0.05). The bonding strength of the coating LC1 is 11.4 N, which is 7.26 times higher than that of the conventional hot-spraying Al2O3/TiO2 coating. It has been proved by analysis that the bonding strength is achieved because of the effects of both super-quick laser consolidation and the nanometer effect of nanometer ceramic material.     

铸铁轧辊表面Cr3C2-NiCr涂层的显微组织

研究分析了铸铁轧辊表面等离子喷涂Cr3C2-25NiCr复合涂层的组织结构。结果表明,Cr3C2-25NiCr涂层具有典型的层状结构;涂层质量较好,组织相对紧密,与基体结合尚可;由EDS和涂层物相分析可知,涂层与基体间没有发生元素扩散现象,涂层与基体呈机械结合。     

hBN含量对等离子喷涂NiCr/Cr_3C_2-hBN复合涂层力学性能的影响

采用化工冶金包覆、喷雾造粒和固相合金化技术以Cr3C2和hBN为核心制备了NiCr/Cr3C2-h BN复合粉体,并用等离子喷涂技术制备了NiCr/Cr3C2-hBN涂层,研究了涂层的显微结构、物相组成、显微硬度和结合强度。研究结果表明,等离子喷涂NiCr/Cr3C2-h BN复合涂层呈典型的层状结构,各层之间结合良好。涂层的显微硬度和结合强度均随hBN含量的增加逐渐降低,当hBN含量为20%时,涂层的显微硬度和结合强度分别为NiCr/Cr3C2涂层的66%和50%。涂层断裂位置发生在涂层内部,为典型的脆性断裂。     

固液球磨制备Fe-Sn金属间化合物粉末

采用固液反应球磨专利技术制备Fe-Sn金属间化合物。所谓固液反应球磨，是在一定温度区间，球磨介质对金属液体进行球磨时，磨球和金属液体反应生成固相的金属间化合物粉末。为加速反应进行，可以在金属液体中加人与磨球成分相同的金属粉末。通过固液反应球磨制备了FeSn2，FeSn，Fe3Sn2和Fe1,3Sn4种金属间化合物纳米粉末，并对固液反应球磨技术制备金属间化合物的机理和特点进行了讨论。     

激光熔覆Co-Cr-Ni-Mo涂层的粘塑性摩擦及组织演变行为(英文)

通过激光熔覆Co-Cr-Ni-Mo合金与WC-Co硬质合金之间的旋转摩擦变形实验,研究钴基合金的粘塑性摩擦及纳米组织形成机制。考察粘塑性摩擦过程的摩擦系数、界面温度及轴向缩短量随时间的变化关系。结果表明以上物理量首先进入快速上升阶段,然后进入稳态阶段,其中第一个阶段属于滑动摩擦,第二阶段属于粘塑性摩擦。粘塑性摩擦后,激光熔覆涂层从表面至内部可分为粘塑性变形区、热力影响区、激光原始组织3个典型区域。粘塑性变形可将原始组织中的网状M23C7相破碎为弥散分布的等轴形状纳米晶粒。粘塑性区的宽度为37～131μm,其典型组织特征为晶粒尺度小于50nm的M23C7相及α-Co相,甚至含有少量接近非晶态结构。因而,粘塑性摩擦将激光熔覆合金的硬度由HV600提高至HV997。     

Q235钢滚珠滚压表面变形分布规律及微观组织演变

提出一种新的复合组织制备工艺方法,即首先通过对板坯采取滚珠滚压的方法来实现其表面塑性变形,随后对板坯进行再结晶退火细化表面微观组织。采用有限元法对Q235坯料的滚珠滚压工艺进行数值模拟,得出了表面应变的分布规律,并且对滚压后及再结晶退火后的金相组织进行了观察。结果表明:滚珠滚压工艺能够实现板坯的表面塑性变形,辅以后继的再结晶退火工艺可以获得表面细晶组织和心部粗晶组织的复合组织。     

自蔓延法在金刚石表面形成碳硼化铝涂层的研究

采用Ti/Al/B/金刚石粉体为原料,通过自蔓延高温反应技术,制备了Al-TiB2结合剂金刚石复合材料,在金刚石表面合成了碳硼化铝涂层。采用X射线衍射(XRD)、扫描电镜(SEM)结合能谱仪(EDS)分析试样。研究结果表明:各种原料经自蔓延高温烧结后,产物的主相为Al、TiB2和金刚石。同时当Al质量分数较高时(60%~80%),在金刚石表面形成了致密的碳硼化铝涂层,呈薄片状,金刚石附近也生长出许多碳硼化铝晶粒,尺寸可达到几十微米。但是当Al质量分数较低(40%和50%)时,金刚石会发生严重的碎裂。     

CNTs辅助球磨对Zr粉形貌和氧化性能的影响

研究了不同球磨时间条件下CNTs辅助球磨对Zr粉形貌和氧化性能的影响。采用XRD和SEM分析了球磨过程中Zr粉的物相组成和形貌演变,采用热重（TG）法评估了Zr粉的氧化性能。结果表明：添加CNTs辅助球磨对Zr粉的物相组成没有影响,但是会影响Zr粉的形貌和氧化性能。不添加CNTs时,随着球磨时间的增加（1 h~3 h）,Zr粉粒径持续减小,球磨3 h后,Zr粉粒径由十几 μm减小到2~3 μm。添加CNTs辅助球磨后,Zr粉的颗粒细化过程滞后,球磨初期（1 h~2h）,Zr粉粒径没有显著变化,直到球磨时间延长到3 h时,Zr粉粒径才开始明显减小。这是因为CNTs在Zr颗粒表面的黏附和CNTs在Zr粉中的团聚阻碍了磨球对Zr颗粒的机械冲击和破碎作用。与直接球磨Zr粉相比,当所得Zr粉粒径相差不大时,添加CNTs辅助球磨使Zr粉的起始氧化温度和峰值氧化温度降低了11 ℃ ~37 ℃,这是因为CNTs的良好导热性促进了Zr粉氧化过程中的传热。另一方面,球磨时间少于2 h时,Zr/CNTs混合物中Zr粉的氧化增重量比纯Zr粉的增重量略有降低,但球磨时间超过2 h时,这种趋势出现反转。前者是因为短时间球磨时,CNTs引起Zr粉的局部团聚,阻碍了团聚体中Zr粉与氧气的接触,并且混合物中的Zr粉颗粒还没有被明显细化,这都降低了Zr粉的氧化程度;随后的反转趋势是因为球磨时间增加后,混合物中的Zr粉开始明显细化,促进了其氧化反应的进行,但是纯Zr粉由于颗粒尺寸提前细化而发生了显著的自发氧化,降低了活性Zr的含量。     

激光合金化Ni-W-Si涂层的组织与性能研究

以Ni-W-Si合金为原料,利用激光合金化技术在AISI 304不锈钢表面上制备了以W_5Si_3的复合相为增强相的Ni-W-Si涂层,用SEM、XRD与EDS等方法分析了合金的显微组织、相组成及成分,讨论了不同W、Si含量对涂层组织和耐磨性能的影响。结果表明,涂层中析出了大量花瓣状或胞状W_5Si_3、CrSi_2及(Fe,Ni)复合相,对提高涂层抗磨损能力有良好的增强作用;含W量较高的粉末经激光合金化后残余大量未熔W颗粒,新相以其为形核中心析出并长大形成夹心结构;涂层磨损机制主要为磨粒磨损,高强韧的W_5Si_3相使涂层的显微硬度显著提高(最高达10400 MPa),并使室温干滑动摩擦磨损抗性提高了3~8倍。     

Comparison of molybdenizing and NiCrAlY coating on Ti and Ti-6Al-4V

Two surface treatments, molybdenizing and depositing NiCrAlY coating, were applied to improve the microhardness and the oxidation resistance of titanium and Ti-6Al-4V. Coupons were analyzed using optical microscopy (OM), scanning electron microscopy (SEM) with X-ray energy dispersive spectrometer (EDS), and X-ray diffraction (XRD). Vickers hardness and isothermal oxidation tests were carried out to evaluate the effects of these two surface treatments on the microhardness and oxidation resistance of the substrates. The post vacuum heat treatment of the NiCrAlY coating and the molybdenizing parameters were also discussed. It is found that molybdenizing can obviously increase the surface hardness of titanium due to the formation of β, α″, and α′ phases in the diffusion layer. As γ′ phase is formed after vacuum heat treatment, the NiCrAlY coating is effective in improving the surface hardness of Ti-6Al-4V. The NiCrAlY coating can obviously decrease the oxidation rate of Ti-6Al-4V at 700–900°C, which can be attributed to the formation of Al₂O₃ and Cr₂O₃ mixed scale during the oxidation.     

Microstructural effects and large microhardness in cobalt processed by high pressure torsion consolidation of ball milled powders

The effects of plastic deformation on Co microstructure after a high pressure torsion (HPT) process on unmilled and ball milled powders have been studied and compared to those induced simply by ball milling (BM). X-ray diffraction analyses reveal that both processing routes generate large amounts of stacking faults in Co, which result in a mixture of hcp and fcc phases. However, significant differences in the amount and type of faults accumulated are encountered between BM and HPT. The combination of both processing routes induces a heavily distorted microstructure in Co. In particular, BM+HPT brings about a drastic reduction in crystallite size. Remarkably, high values of microhardness (in excess of H_V=7.3 GPa) are obtained in foils prepared by long-term milling followed by HPT. It is proposed that, in addition to the crystallite size refinement, the large amounts of twin faults, together with the two-phase mixture, also contribute to enhance the microhardness.     

YG8硬质合金表面激光熔覆WC/TiC/Co涂层的组织及性能

通过激光熔覆方法在YG8硬质合金表面制备WC/TiC/Co涂层,借助扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)观察组织结构并分析其物相组成,并对其显微组织、硬度分布和摩擦磨损性能进行了观察和测量。结果显示:涂层表面平整,与基体结合紧密,截面形貌良好没有明显缺陷。表层和两侧存在未熔的WC颗粒,熔覆层中WC颗粒消失,新产生的组织分布均匀。受激光影响,热影响区中的WC晶粒发生重结晶和再结晶。熔覆层主要物相为WC、W₂C、(Ti,W)C_1-x、M₆C(Co₄W₂C、Co₃W₃C)等,这些硬质相和碳化物的生成及弥散分布提高了熔覆层性能。通过测量,熔覆层硬度分布在1700~1800 HV0.5,最高为1783 HV0.5,高于YG8硬质合金,而热影响区和基体的硬度则稍有下降;耐磨性也有大幅提高,熔覆层体积磨损量比YG8合金减少90.67%,平均摩擦因数为0.293,主要磨损形式为磨粒磨损。