WC_P增强铁基复合材料在冷轧带肋轧辊上的应用

通过离心铸造法制备了WC颗粒增强铁基复合材料冷轧带肋轧辊,并研究了复合材料带肋轧辊工作层内WC颗粒分布、界面结构、基体组织和力学性能以及带肋轧辊使用效果。研究结果表明:离心铸造法制备的复合材料冷轧带肋轧辊的复合材料工作层厚度可达20~50 mm,复合材料层中WCP分布均匀,体积分数达到约70%~80%,复合材料工作层硬度HRA 60~63,耐磨性是高速钢的2倍以上。芯部基体组织为贝氏体、石墨和少量复合碳化物,芯部基体硬度为HRC 43~45,冲击韧度大于60 kJ/m2,复合材料辊环的使用寿命与同WC体积分数的硬质合金轧辊相当,价格降低50%左右。     

颗粒增强铁基复合材料的显微结构及性能研究

采用粉末冶金法制备Al2O3、ZTA及WC颗粒增强的铁基复合材料,并对其显微结构和硬度进行了测试分析。结果表明,Al2O3与铁基之间有明显缝隙;ZTA与铁基结合良好,无明显缝隙;WC与铁基呈冶金结合,无缝隙。复合材料基体硬度达到62 HRC,ZTA、WC颗粒硬度分别达1 500 HV、2 800 HV。     

高速钢轧辊的激光熔覆试验研究

采用500W脉冲激光器对冶金精密轧辊进行激光熔覆Ni+WC粉末,用金相显微镜和扫描电镜对熔覆层显微组织和成分分布进行分析,并用显微硬度计测试硬度.结果表明:涂层与基体为冶金结合,涂层的显微组织细化;激光熔覆层表面硬度高达1076HV,而基材硬度为655HV.     

MC3钢冷轧工作辊水淬油冷工艺参数控制

在MC3钢冷轧工作辊淬火冷却过程中,水淬油冷工艺参数的不稳定,造成轧辊的组织性能相应变化,最终使轧辊使用寿命降低。根据失效轧辊组织性能的分析结果,设计了不同水淬油冷工艺,对MC3钢模拟轧辊力学性能和显微组织进行了测试与分析,得到不同的硬度梯度分布曲线和冲击性能变化规律。对比轧辊的失效分析结果,水淬210 s再油冷的MC3钢试块硬度可达61 HRC,并且具有平缓的硬度梯度和较好的基体韧性。     

机床用WC/Al_2O_3复相陶瓷刀具材料的研究

以WC和α-Al_2O_3为主要原料,采用真空热压烧结工艺制备机床用WC/Al_2O_3复相陶瓷刀具材料。测试和分析了烧结样品的相对密度、弯曲强度、断裂韧度、硬度值、相组成以及显微结构。结果表明,当WC添加量为75%,微米α-Al_2O_3添加量为25%,烧结温度为1 600℃时,所制备的WC/Al_2O_3复相陶瓷刀具材料性能最佳,相对密度值为99.1%,弯曲强度为706.3 MPa,断裂韧度为8.91 MPa·m1/2,硬度值为19.14 GPa。最佳样品的主晶相为碳化钨(WC)和刚玉(Al_2O_3)。     

超粗晶WC-Co硬质合金的研究现状

超粗晶硬质合金是一类性能优异的新型合金,广泛用于采矿、凿岩、轧辊等领域,应用前景广阔。化学包覆法和纳米粉末溶解法是超粗晶WC-Co硬质合金制备的主要方法,介绍了超粗硬质合金原料WC颗粒平均粒度选择的动力学理论,碳含量对超粗合金中WC晶粒生长粗化的影响以及通过引入其它元素强化粘结相以提高合金寿命的探索结果。此外,分析了以合金硬度为常数时,晶粒尺寸与合金性能的关系,指出在保持合金硬度不变时,通过增大WC晶粒尺寸来提高合金的耐磨性和韧性是可行的。最后,展望了超粗晶合金的发展方向。     

铁镍比与VC对WC-15%(Fe,Ni)细晶硬质合金组织与力学性能的影响

利用OM、SEM、XRD进行微观组织与相组成分析,研究了铁镍比与VC对铁镍基硬质合金组织性能的影响规律。结果表明:添加质量分数0.5%的VC可显著提高合金硬度并细化组织,铁镍比越低,合金硬度提高幅度越大、组织细化效果越显著。当铁镍质量分数比为1∶5时,添加0.5%VC的合金硬度达91.5 HRA,WC平均晶粒度为0.6μm,相比于没有添加VC的合金,硬度增幅为4.7 HRA,WC晶粒尺寸降幅为2.4μm。当铁镍质量分数比小于1∶3时,VC的添加可提高合金抗弯强度,当铁镍质量分数比大于1∶3时,VC的添加反而降低合金抗弯强度。当合金中没有添加VC时,铁镍比的降低导致合金硬度下降,同时合金组织中的WC晶粒也明显粗化,这是由于WC在铁中的固溶度较小,铁含量的增加可有效抑制WC的溶解析出长大。当合金中添加VC时,铁镍比对合金硬度与晶粒度影响均较小,合金硬度均在91～92 HRA范围内,合金中WC平均晶粒度均为0.6μm。在合金抗弯强度方面,随着铁镍比的降低,有无添加VC的合金抗弯强度均整体呈先下降后上升的趋势,并分别在铁镍质量分数比1∶3与1∶2时达到峰值。综合来看,铁镍质量分数比1∶3,添加...     

WC颗粒增强回转体表面制作轧辊工艺及性能研究

通过试验，探索用离心铸造工艺实现回转体表面铸渗WC颗粒制作轧辊的工艺，并在自制的三体磨损试验机上，验证考察该轧辊表面复合层抗磨料磨损的性能，结果表明，用合适的工艺可以实现在回转体（基体为HT200）表面离心铸渗WC制得轧辊，所得轧辊表面的常温抗磨料磨损性能较之Cr20(回火处理）的提高3－4倍。     

球墨铸铁轧辊电火花沉积层组织结构和性能

采用电火花沉积方法将YG8电极材料沉积在球墨铸铁轧辊材料上,制备了WC沉积涂层,研究了其微观组织及耐磨性能.结果表明:沉积层主要由Fe_3W_3C、Co_3W_3C、W_2C和Fe_7W_6等相组成,沉积层与基体呈冶金结合,Fe_7W_6、W_2C等硬质相弥散分布于沉积层中,部分区域硬质相达到了纳米颗粒尺寸;沉积层硬度分布不均匀,平均硬度为1759 HV0.3;沉积层具有优异的耐磨性,其磨损性能是基体的3.7倍;沉积层的磨损机理以粘着磨损和疲劳磨损为主,细小的弥散分布的硬质相是沉积层硬度以及耐磨性提高的主要因素.     

900mm中宽带热连轧机高速钢轧辊的研制与应用

针对热轧中宽带轧机进行了离心复合高速钢轧辊的研制与试用。试用结果表明,高速钢轧辊的磨损 量仅为高铬铸铁轧辊的1/3-1/8,下机后辊面温度和硬度合理,辊面光洁度高,氧化膜均匀、致密,可以提高生产效率,降低轧辊消耗,延长换辊周期,减少换辊次数。     

Electrical conductivity of 1 : 1 and 2 : 1 clay minerals

The A.C. impedance plots were used as tools to analyze the electrical response of two varieties of Tunisian halloysite 1: 1 and illitic samples 2: 1 as a function of frequency at different temperatures (80–800°C). The real and imaginary parts of the complex impedance trace semicircles in the complex plane. Except for the illite, It-1, the second sample analyzed in this study, these plots give evidence for the presence of both bulk and grain boundary effect, above 600°C onwards. The bulk resistance of the materials decreases with the rise in temperature. Impedance Spectroscopy data reveal a non-Debye type of dielectric relaxation. The Nyquist plots show the negative temperature coefficient of resistance of both pure Tunisian illite and halloysite samples. The results of bulk electrical conductivity and its activation energy are presented for the two mineral clay samples. For illite It-1, the activation energy values estimated from the AC conductivity pattern and modulus pattern are very similar and suggest a possibility of a long-range mobility of charge carriers (ions) via hopping mechanism of electrical transport processes at higher temperature. On the other hand, for the halloysite sample provided from kasserine, (Ha-Kass), the modulus analysis admit that the electrical transport processes of the material are very likely of electronic nature. Relaxation frequencies follow an Arrhenius behavior with the activation energy values not comparable to those found for the electrical conductivity.     

1SRQ1系列全数字软起动器

文章介绍了软起动器的产品特点和主要技术性能指标，并与部分传统控制方式作了一些比较。     

Stabilization of extended stacking faults by {1 1 1}/{1 1 2} twin junction interactions

Extended stacking faults, with lengths of up to 10 nm, that join {1 1 1}/{1 1 2} twin-boundary junctions were observed by high-resolution transmission electron microscopy (HRTEM) in gold thin films. Circuit analysis shows that these defects possess a Burgers vector of 1/3〈1 1 1〉. In order to explain the generation of these extended defects, we consider the behavior of 1/3〈1 1 1〉 dislocations at {1 1 1}- and {1 1 2}-type twin boundaries and near {1 1 1}/{1 1 2} twin-boundary junctions using HRTEM observations and theoretical modeling. By establishing the interaction forces that lead to this defect configuration, our analysis shows that the relief of intrinsic strain at the junction corners, which results from the incompatibility of the translation states at the intersecting boundaries, is sufficient to stabilize the stacking fault extension. Because grain–boundary junctions possess intrinsic strain fields whenever they join boundaries with incompatible translation states, similar mechanisms for stacking fault emission may arise between other closely spaced grain–boundary junctions.     

20Cr1Mo1V1钢的分级时效工艺研究

研究了 2 0Cr1Mo1V1钢的强韧化工艺。所优化出的分级时效工艺能使其强度和韧性达到质保书的要求。     

A contribution to the crystallochemistry of ternary 1:1:1 and 1:1:2 rare earth intermetallic phases with Pb and Pd

The ternary alloys of the rare earths with lead and palladium were studied for the stoichiometric ratios 1:1:1 and 1:1:2 with respect to the structure of these alloys and their existence field. RPbPd (R = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Y, Ho, Er, Tm, Yb) compounds have a hexagonal structure, hP9 Fe₂P type, while RPbPd₂ (R = Pr, Sm, Gd, Tb, Dy, Ho, Er, Yb) alloys have the cubic AlCu₂Mn-type structure (cF16, BiF₃ superstructure).