B-C-N三元物相体系的结构与合成

本文就B－C－N三元体系中，合成的类石墨和类金刚石的物相形态研究工作进行了评述，指出，在B－C－N体系中，由于B，C，N原子半径接近，而有希望制得类石墨的，也可制得类金刚石的新材料提供了可能，由此可以预示，类石墨结构的三元化合物可用于制备高温半导体，而类金刚石结构的材料，则将具有比立方氮化硼更高的硬度和比金刚石更好的热稳定性，因此，从实用的观点来说，合成复合（杂化）结构的材料是有意义的，讨论了三元物相有希望的方法，及其结构模型和热稳定性。     

铸铁拘束试件的拘束度计算及铸铁焊缝裂纹倾向定量评定

本文提出了一种试件拘束度分级可调的铸铁焊缝拘束裂纹定量新方法，采用有元元方法对铸铁试件拘束度进行了计算，并做了实测验证，应用本试验方法测定了石墨形态对铸铁焊缝裂纹倾赂的影响。     

稀土元素Ce对石墨球化作用的研究

通过凝固过程中的热分析试验,研究了稀土元素Ce对Ni-C二元过共晶合金凝固过程中过冷度及石墨生长形态的影响.结果表明,加入稀土元素Ce,初生相石墨结晶时的过冷度显著增大,凝固组织中的石墨形态由片状生长转变为球状生长;但加入Ce后,若提供一个小的过冷条件,石墨将以片状形态生长,表明凝固时的过冷是促进石墨球状生长的主要因素;稀土元素Ce并非是石墨球化的充分条件.     

在砂型铸造时根据灰铸铁件化学成份和壁厚计算铸件抗拉强度的方法

灰铸铁件的抗拉强度,主要是由铸铁的基体组织和石墨析出物的数量大小及形态分布所决定的。而铸件的基体组织和石墨析出物数量大小及形态分布则主要取决于铸件的化学成份(碳当量及合金元素的含量)和铸件的壁厚。过去,国内有关灰铸铁强度与铸件化学成份及壁厚关系的资料不少,然而用公式的形式来定量地表示这一关系的资料虽然在国外早有报导,但在国内至今仍较缺乏。下面,介绍一种直接根据铸件壁厚和化学成份计算铸件抗拉强度的方法。     

基于分形的铸铁石墨颗粒形态的评定方法

提出了基于分形的铸铁石墨颗粒形态评定的三种方法，研究了分形参数用于描述石墨颗粒形态物理意义，讨论这些方法的实际应用。     

用含硼掺杂物石墨碳源合成金刚石的实验

本叙述了用含硼掺杂物石墨碳源材料合成金刚石的效果，讨论了石墨碳源中含硼掺杂物种类及其掺量对金刚石晶体生长性能及其质量的影响，在对含硼掺杂物石墨碳源多种性能进行测试与分析的基础上，指出了选择金刚石碳源的重要性，必要性及原则。     

基于可拓理论的刀具磨损状态评价方法的研究

基于物元模型的可拓学理论分析,提出了刀具磨损状态的可拓评价方法。利用与刀具磨损状态密切相关的敏感特征参数,构造经典域物元和节域物元,应用物元和可拓集合中的关联函数,建立了刀具磨损状态的可拓评价模型,通过可拓评价分析,获得了客观合理的评价结果。实例分析证明了可拓学理论用于刀具磨损状态评价的有效性和可靠性。     

消失模铸造铁液及凝固特性对灰铸铁石墨组织的影响

在生产条件下,通过附铸阶梯试样的方法,研究了消失模铸造灰铸铁石墨形态的特点,结果表明,消失模铸造灰铸铁较易出现过冷石墨.讨论了消失模铸造特点及消失模铸造高温铁液及充型凝固特点对石墨形态的影响.     

悬浮浇注对大断面球铁石墨形态及凝固特性的影响

研究了悬浮浇注对模拟大断面球铁试块石墨形态及凝固特性的影响，并初步分析了悬浮浇注的作用机理。试验结果表明，悬浮浇注可明显改善大断面球铁的石墨形态和凝固特性。     

碳（石墨）纤维增强镁基复合材料的界面研究

采用透射电子显微技术及高分辨技术，对Ｃ／Ｍｇ复合材料界面的显微结构进行了研究，发现在纤维与基体的界面上存在着Ａｌ元素的偏聚；碳纤维的石墨化程度不同，界面形态不同，石墨化程度较低时，界面处有一层约１μｍ厚的细晶粒层存在，石墨化程度较高时，界面处平直光滑；界面处有析出物γ－Ｍｇ１７Ａｌ１２存在；近界面区存在着大量晶体缺陷，主要为位错和孪晶，并有残余应变层存在；当碳纤维表面有ＳｉＣ涂层时，在涂层与基体间     

基于Matlab的球铁石墨的定量分析

随着铸铁产业的持续发展,球墨铸铁中石墨图像的定量分析迫切需要一种简便、精确、自动的检测方法。采用Matlab图像工具箱编程,对球墨铸铁石墨图像进行灰度变换、边缘检测、图像形态学及种子填充等一系列图像处理,其中在边缘检测中采用Roberts算子与Canny算子相结合的方法。在分析石墨颗粒形态特征和分布特征的基础上,提取了整体似圆度、取向角、分布距离以及石墨面积百分数4个特征量,利用这4个特征参数可以综合地反映球铁中石墨颗粒的形态及位置状态。对不同冷却条件下球铁试样中的石墨图像进行了分析,结果表明该方法能有效地用于球铁石墨的定量分析。     

孕育方法对消失模铸造灰铸铁组织性能的影响

针对消失模铸造灰铸铁过程中石墨形态及力学性能不稳定的问题,通过在生产条件下附铸阶梯试样及试棒的方法,研究了不同孕育处理方法对消失模铸造灰铸铁组织和性能的影响。结果表明,浇注过程中进行瞬时孕育并控制孕育量在一个适宜的范围内,可明显改善石墨形态和基体组织,同时力学性能得到提高。瞬时孕育量为0.25%时,可基本消除灰铸铁过冷石墨,同时细化基体,抗拉强度较炉前孕育试样提高15 MPa。     

Different thermal fatigue behaviors between gray cast iron and vermicular graphite cast iron

The initiation and propagation of thermal fatigue cracks in gray cast iron and vemicular graphite cast iron were investigated by Uddeholm method to reveal the complex thermal fatigue behaviors of cast iron. Differences of thermal fatigue behaviors of gray cast iron and vemicular graphite cast iron were observed and analyzed. It is found that the observed differences are related to the combination of graphite morphology and the oxidization of matrix. More oxidized matrix is observed in gray cast iron due to its large specific surface area. The brittle oxidized matrix facilitates the propagation of microcracks along the oxidization layer. By contrast, the radial microcracks are formed in vermicular graphite at the edge of graphite due to fewer oxidization layers. It indicates that the thermal fatigue resistance of gray cast iron is dominated by graphite content and morphology while that of vermicular graphite cast iron strongly relates to the strength of the matrix.

     

石墨/铜铁基自润滑复合材料的摩擦学性能研究

采用感应加热烧结粉末冶金的方法,以铜铁合金为基体,添加石墨制备石墨/铜铁基自润滑复合材料,对比研究了添加石墨前后2种材料的组成、结构、表面形貌及摩擦学性能,并分析了磨损机理。研究结果表明:添加石墨能起到润滑作用,使材料的摩擦因数减小,磨损率降低;添加的石墨一部分转化成新态,其余则进入材料的空隙中,在摩擦过程中形成润滑膜起到减摩的作用;添加石墨后,摩擦材料的磨损机制由粘着磨损变为磨粒磨损。     

Numerical simulation of microstructure evolution on near eutectic spheroidal graphite cast iron

A multiphase cellular automaton model was developed to simulate microstructure evolution of near eutectic spheroidal graphite cast iron (SGI) during its solidification process, and both dendritic austenite and spheroidal graphite growth models were adopted. To deduce the mesh anisotropy of cellular automaton method, the composition averaging and geometrical parameter were introduced to simulate the spheroidal graphite growth. Solute balance method and decentered square algorithms were employed to simulate austenite dendrites growth with different crystallographic orientations. The simulated results indicate that the graphite nodule grows in a spherical morphology when the surrounding environment of a single graphite nodule is same. However, for two adjacent graphite nodules, the environment is different. The higher the carbon concentration, the faster the growth of graphite. By comparison with experimental results, it is found that the microstructure evolution of near eutectic spheroidal graphite cast iron during solidification process can be reproduced quantitatively by numerical simulation with this model.     

镀铜石墨粉的制备研究

表面镀铜的非金属材料是当前功能材料开发的一个热点.利用化学镀的方法在石墨粉的表面进行化学镀铜,通过对化学镀铜沉积速度和镀层表面形貌进行分析,探讨了如何获得表面包覆良好的镀层.石墨粉表面化学镀铜工艺可以分为表面预处理、化学镀和性能测试三大步骤.研究重点放在化学镀施镀步骤上,对化学镀铜的影响因素进行了研究,得出最佳的镀铜工艺配方,并将此配方应用于实际,得到了色泽光亮、分散性好的石墨镀铜粉.     

Effects of transition from lamellar to compacted graphite on thermal conductivity of cast iron

Abstract

Different levels of magnesium were added to a standard grey iron alloy in order to obtain a range of graphite morphologies from lamellar to compacted graphite. The thermal conductivity/diffusivity of samples, solidified at different cooling rates, was investigated by means of the laser flash technique. There is a significant decrease in the thermal conductivity as the morphology transits from lamellar to compacted graphite. The thermal conductivity of grey iron decreases considerably at elevated temperatures, whereas the thermal conductivity of compacted graphite iron is less sensitive to changes in temperature. At increased nodularities, compacted graphite irons exhibit a maximum thermal conductivity at ～400°C. The influence from the cooling conditions on the thermal conductivity decreases as the morphology alters from lamellar graphite to compacted graphite. The effective thermal conductivity of cast iron is modelled by means of existing models for composites.     

稀土蠕化剂对蠕墨铸铁石墨形态和性能的影响

对以云南地方生铁为主要炉料的铁液,搭配使用稀土硅铁合金和稀土镁合金作为蠕化剂,研究了稀土蠕化剂加入量对蠕墨铸铁石墨形态和性能的影响。研究结果表明,随着稀土蠕化剂加入量的增加,铁液中稀土残留量逐渐增加,石墨形态从片状逐渐向球状过渡,抗拉强度和硬度逐渐上升。实践证明,通过合适的蠕化处理工艺,云南地方生铁铁液可以获得组织和性能较为理想的蠕墨铸铁。     

Influence of graphite morphology on dry sliding wear of flake graphite cast irons

Abstract

Four flaky graphite cast irons of different graphite structures with a pearlitic matrix were prepared to clarify the graphite structure's influence on the dry sliding wear property. Two melts of cast iron with different carbon contents were solidified at two different cooling rates. The four resultant samples had type A flaky graphite or type D eutectic graphite structure with different graphite volume fractions and fully pearlitic matrixes. A pin on the disc type wear test evaluated the four samples' dry sliding wear properties. Results showed that the type D graphite structure wore down faster than the type A graphite structure did. The type of graphite morphology influenced the specimen wear rate as strongly as the graphite volume fraction did in flaky graphite cast irons of this experimental range.     

新型Ni3Al/石墨高温固体自润滑材料的制备及其性能

采用熔炼法, 制备出新型Ni3Al/石墨抗高温、耐腐蚀固体自润滑材料.结果表明: Al不仅是强化合金基体的元素, 而且是一种使片状石墨转变为球状石墨的球化剂; 铝与氧结合成渣降低了氧在石墨表面的吸附.建立了界面能和过冷度对石墨生长形态影响的动力学模型; 分析表明, 石墨在洁净的液态金属中结晶, 由于(1010)棱面与(0001)基面的温度回升速率的差异, 促使石墨球状生长.石墨经球化处理后, 材料的冲击韧性得到提高; 将该材料与GCr15轴承钢及45﹟退火钢进行干摩擦磨损时, 摩擦因数分别为0.36和0.40.