Al-Sn预合金粉末及其在金刚石磨具中的应用

通过超声雾化法制备Al-Sn预合金粉末，研究Al—Sn预合金粉末的形貌、热压性能、抗氧化性能及其在铝基金刚石磨轮中的应用情况。结果表明：制备的Al—Sn预合金粉球形度高，与相同组成的单质Al、Sn混合粉末相比，其抗氧化性能提高2．23倍，而热压温度低50℃左右，且热压后组织均匀；预合金粉末有利于制备的铝基金刚石磨轮的成分均匀。     

具有孔隙结构的金属基金刚石工具的研究进展

在金属基金刚石工具中引入孔隙结构,旨在增加容屑空间和冷却效果,从而提高工具性能。然而,孔隙率增加导致的工具力学性能急剧下降,限制了工具的服役性能。近年来科研人员开发了多种金刚石工具制备新方法,制备的工具孔隙结构从整体均匀化向局部有序化转变,同时工具的性能和成本等也呈现出较大差异。因此,本文首先介绍多孔金属基金刚石工具的孔隙结构特点及其对性能的影响,然后围绕制备多孔金属基金刚石工具的热压法、增材制造法和激光修整法,系统总结了各制备方法的原理和参数调控要点,重点梳理了工具的制备工艺参数-孔隙结构-力学性能-服役性能之间的对应关系,最后评述各制备方法的优缺点及适用范围,探讨多孔金属基金刚石工具可能的发展方向。     

金刚石磨具及其制作方法

本发明涉及一种金刚石磨具及其制作方法,金刚石磨具的磨削层包括嵌设在树脂基体内的金刚石磨块,金刚石弯块的外表面为非规则的折叠压纹。金刚石磨块为直立、弯曲或倾斜的圆柱、棱柱、圆台、圆锥台或棱锥台状,其表面设置有非规则的多层折叠压纹。金刚石磨块顶部和／或底部设置有突起。树脂基体及金刚石磨块成型在夹持头上;或者,树脂基体及金刚石磨块成型在尼龙丝层或尼龙钩层上,与此对应的尼龙钩层或尼龙丝层设置在中间体的顶面和／或侧面,     

金刚石磨头电火花车削修整技术研究

工具的精确设计和修整是电解加工的研究难点之一。由于特殊的制造工艺,铜基烧结金刚石磨头存在较大的圆跳动误差。为减小圆跳动误差,需对金刚石磨头进行修整。为此,提出了一种新的修整方法——电火花车削修整技术。利用该技术,可将金刚石磨头的圆跳动误差修整到0.003 mm。利用已修整的金刚石磨头和未修整的金刚石磨头分别对304不锈钢进行电解磨削,通过宏观和微观对比发现,采用电火花车削修整的磨头磨削精度高,加工误差小,且加工表面均匀,表面粗糙度值低、质量好。     

Fe基胎体中添加Zn粉后的金刚石磨边轮组织及性能

在金刚石磨边轮Fe基胎体中分别添加0,0.7%,2.1%,3.5%,4.9%质量分数的Zn粉,研究Zn粉添加量对金刚石磨边轮Fe基胎体的热压烧结组织、物相组成及力学性能的影响;在此基础上,研究Fe基胎体中添加0、2.1%、3.5%质量分数的Zn粉以及浓度为24%的金刚石后制成的3种金刚石节块的性能及对应的3种磨边轮的磨削性能。结果表明:当采用相同烧结工艺时,不添加和添加Zn粉后的Fe基胎体中的白色、深灰色、灰色3种组织面积及存在形态明显变化,加入质量分数为2.1% 的Zn粉有助于胎体中部分物质扩散,且其物相除γ-Fe、(Cu, Sn)和(γ-Fe, Ni)、Cu₄₁Sn₁₁固溶体以及Fe₄Cu₃、Ni₄Sn等金属间化合物外,还出现了Cu_0.61Zn_0.39新相。Zn粉质量分数增加,Fe基胎体的相对密度、硬度、耐磨性等皆呈下降趋势,但降幅不明显;而其抗弯强度相对未加Zn粉时的呈先增大后减小趋势,且在Zn粉添加质量分数为2.1%时提高了16.1%,达到最大值983.2 MPa;但添加的Zn粉质量分数过高,胎体热压时会出现流料现象。添加或未添加Zn粉的Fe基胎体中加入金刚石后,制作的节块与未加金刚石时的比,其抗弯强度下降,但添加Zn粉后的胎体抗弯强度降幅较小,把持力系数较大,可间接表明胎体对金刚石的把持力较高。用添加质量分数为2.1% 的Zn粉的Fe基胎体制作的金刚石磨边轮磨削渗花陶瓷砖边时,与胎体中未添加Zn粉和添加质量分数为3.5%的Zn粉制作的磨边轮磨削效果比较,其锋利度适中,使用寿命最长。      

预烧结温度对热等静压法制备Co基金刚石串珠性能的影响

采用合适的工艺流程及参数,将热等静压(Hot Isostatic Pressing,HIP)技术应用于Co基金刚石串珠制备。分析了HIP后胎体性能的变化,并通过扫描电镜(Scanning Electron Microscope,SEM)进行断面微观分析。结果表明:相比较热压烧结,HIP更有助于改善Co基胎体各项性能,对于实验中各组Co基胎体,750℃预烧结胎体的性能提高最多,其中胎体抗弯强度提高了25.2%,胎体对钢基体的夹持力提高了37.9%。显然,HIP可用于Co基金刚石串珠的制备,而预烧结温度对HIP后胎体性能有着重要影响,在合适的预烧结温度下可以获得最佳性能的胎体。     

加工电熔锆刚玉砖用电镀金刚石磨轮的研制和应用

电熔锆刚玉砖是玻璃熔窑最重要的耐火材料,该砖结构致密、热稳定性高、耐磨性好、抗蚀能力强,只有超硬磨料才能对锆刚玉砖表面进行有效磨削。本文通过复合电镀方法研制和生产金刚石磨轮,并给出了复合电镀金刚石磨轮的工艺流程。在研制过程中,对金刚石磨轮的基体和胎体进行了优化设计,分析了金刚石质量、金刚石浓度、金刚石粒度对磨削过程的影响,采用两种品级、四种粒度的金刚石按一定比例混合使用,扩大了磨轮的适用范围,提高了磨轮的自锐性,研制的电镀金刚石磨轮用于磨削锆刚玉砖耐火材料,其平均使用寿命达到168．36m^2,与热压焊接金刚石磨轮比较,平均寿命和磨削效率分别提高16．5％和20％。使用结果表明：电镀金刚石磨轮是最适合磨削加工电熔锆刚玉砖的金刚石工具,加工后的锆刚玉砖具有精确的几何形状和高光洁度的表面,同时,选择合适的金刚石磨轮和合理的磨削参数,对电镀金刚石磨轮的使用寿命和磨削效率以及锆刚玉砖的加工质量有重要影响。     

铝基金刚石复合材料热性能的数值模拟与实验验证

利用有限元软件建立铝基金刚石复合材料的代表性体积单元,研究了不同的金刚石体积分数及粒径对铝基金刚石复合材料导热系数和热膨胀系数的影响.同时采用挤压铸造的方式制备出各种铝基金刚石复合材料样件,并测量出其导热系数和热膨胀系数,将有限元模拟结果与实验结果进行了对比验证.结果表明:有限元模拟结果与实验结果吻合较好;当金刚石粒径...     

高效加工硬质合金沉孔用新型金刚石工具与工艺研究

介绍了一种加工硬质合金沉孔用新型金刚石工具与加工工艺。采用电镀和烧结金刚石磨头在数控铣床上,以螺旋进刀的加工方式,在不同进刀量和进给速度条件下,研究加工效率和磨头寿命的关系;研究不同尺寸、槽型的电镀和烧结金刚石磨头对不同材质的硬质合金沉孔的加工效率和沉孔精度等的影响;并采用扫描电镜（SEM）和光学显微镜分析金刚石磨头的显微组织。结果表明:与电镀金刚石磨头相比,烧结金刚石磨头具有更好的使用寿命和加工效率,将传统硬质合金沉孔（φ13 mm×5 mm）每孔的加工时间由2 h缩短为10~15 min,且每只磨头的打孔寿命约为33~42个。该研究有望进一步增大硬质合金等硬脆带孔材料的应用范围。      

气压浸渗法制备Al2O3短纤维增强铝基复合材料

利用自行设计的试验装置采用气压浸渗法成功制备出Al2O3短纤维增强铝基复合材料,对金相组织和硬度进行了分析,得出了温度、体积分数、压力对浸渗的影响结果.证明了气压制备短纤维铝基复合材料的可行性.     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

The Mirror with Patterns of Auspicious Animals and Grapes——Exquisite cast mirror and the technology of surface tin-enrichment by rubbing-in and infiltration of tin-rich powder

<正>Bronze mirrors were used by the Chinese people before the introduction of the glass mirror.Only after it was replaced by the glass mirror did the bronze mirror gradually retreat from people's lives.Different styles of bronze mirrors were made in different historical periods,particularly in the Warring States Period,the Han and Tang Dynasties,which were the three peaks of the development of bronze mirror arts in ancient China.The casting techniques were exquisite.The surface of the bronze mirror was smooth and bright enough to reflect one's image,and there were scarcely any casting defects on the mirror surface.On the back of the bronze mirror,there were rich depictions of Arts and Humanities,and the ornamentations were also     

The 9th China International Diecasting Congress & Exhibition

The 9th China International Diecasting Congress ＆ Exhibition was held on July 22-24, 2014 at Shanghai New International Expc Centre. This exhibition was the most successful over the years, with over 6890 visitors and 155 exhibitors, and the exhibition area increased by 30% from 9,500 square meters in 2012 to 12340 square meters. Die casting enterprises from a total of 24 countries and regions, including China mainland, Chinese Taiwan and Hong Kong, South Korea, Japan, Germany, India, Thailand, Malaysia, the United States, Russia, Australia, Iran, Ukraine, Brazil, Colombia, Singapore, Austria, Canada, Croatia, France, Turkey, United Kingdom, Vietnam, attended the congress and exhibition.     

Introduction of the Fluid Control Engineering Institute of Kunming University of Science and Technology

正The Fluid Control Engineering Institute of Kunming University of Science and Technology was set up in 1996.The researches of institute concentrate on electro-hydraulic(pneumatic)servo/proportional control and hydromechatronics.The Institute is committed to research and development of electro-hydraulic control of high-end technical equipment in ferrous metallurgy refining produc-     

RARE METALS Volume Contents

正~~     

Antimony Induced Crystallization of Amorphous Silicon

Antimony induced crystallization of PVD (physics vapor deposition) amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystallization can be observed with TEM (transmission electron microscopy). Only a few and much smaller crystals of the order of 1μm were formed when the antimony layer was deposited by MBE (molecular beam epitaxy) compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.     

A CUMULATIVE FATIGUE DAMAGE RULE UNDER THE ALTERNATIVE OF CORROSION OR CYCLIC LOADING

Fatigue damage increases with the applied loading cycles in a cumulative manner and the material deteriorates with the corrosion time. A cumulative fatigue damage rule under the alternative of corrosion or cyclic loading was proposed. The specimens of aluminum alloy LY12-CZ soaked in corrosive liquid for different times were tested under the constant amplitude cyclic loading to obtain S-N curves. The test was carried out to verify the proposed cumulative fatigue damage rule under the different combinations among corrosion time, loading level, and the cycle numbers. It was shown that the predicted residual fatigue lives showed a good agreement with the experimental results and the proposed rule was simple and can be easily adopted.