固体碳氮硼共渗的研究

研究了两段固体碳氮硼三元共渗。通过试验选出了渗剂。用该渗剂对工业纯铁、15钢、45钢等进行570℃×3h—900℃×5～6h共渗处理后,得到由硼化物层和碳氮层组成的共渗层。渗层组织及相结构分析表明:共渗层中有一定数量的ε,γ′和Ee_3(C,B)粒子相,其中ε相最多且以棒条状或小球状存在。还对共渗过程的有关化学反应进行了热力学分析。对渗层的脆性、耐磨性与渗硼进行了对比试验。     

化合物(ε、γ′)层在渗氮及氮碳共渗中的作用

本文作者研究了在渗氮及氮碳共渗过程中氮在化合物(ε、γ′)层和扩散层α[N]中的扩散(流)强度JiN＝-D(dc)/(dx),结果表明,在通常情况下|JεN|/|JαN|1,而|Jγ′N|/|JαN|1,当|Jγ′N|/|JαN|＜1时γ′成为扩散的薄弱环节,阻碍扩散层的发展.化合物ε具有储氮作用,而γ′具有传递氮的作用.γ′相的生成和形貌的控制成为渗氮的关键.     

离子氮碳氧复合渗对45钢耐磨性能的影响

用离子氮碳氧复合渗处理的方法 ,在绝热式离子热处理炉上对 45钢试样进行处理。通过金相显微镜和X射线衍射仪观察了化合物层的显微组织和微观结构及在MPX 2 0 0型盘销式摩擦磨损试验机上进行纯滑动干磨损试验。结果表明 ,45钢经离子氮碳氧复合渗处理后 ,表层可获得化合物和氧化物的复合渗层 ,明显提高 45钢的耐磨性能。     

渗氮及氮碳共渗中的相行为动力学

根据相变理论，分析计算了渗氮及氮碳共渗中各相间相界面的局部平衡及相界面移动的动力学，以及各相的长大和溶解速度，得出渗入过程中各相的行为（简称相行为）规律。这就是ε相层单向长大，γ相层是双向溶解，而α－Ｆｅ（Ｎ）相是双向长大。由此提出提高渗速，改善组织的措施，并在生产中取得明显效益。     

稀土元素对碳氮共渗组织和性能的影响

本文研究了稀土对气体碳氮共渗动力学过程、渗层成分和组织结构、渗层性能的响。通过优化选择了合适的稀土种类，加入量和工艺参数。结果表明，稀土具有明显的催渗作用，与不加稀土相比，可使渗速提高３０％；表层中碳、氮含量增加，碳化物的数量增加、颗粒变得细小、弥散且向内延伸分布。马氏体和残余奥氏体细化；渗层硬度提高，显微硬度分布趋于合理；在高负荷下渗层的耐磨性提高约３０％，经该技术处理的饲料压模的寿命大幅度提高。电子能谱分析和物相分析表明，稀土元素渗入渗层并形成稀土化合物相，起到微合金化作用。     

45钢稀土催渗气体氮－碳－硼多元共渗的研究

在气体软氮化的基础上，加入一定量的稀土催渗剂和供硼剂，进行一系列的稀土催渗气体氮－碳－硼多元共渗的试验研究。试验结果表明，４５钢经稀土催渗氮－碳－硼多元共渗后，可在材料的表面形成较厚的化合物层和扩散层。使材料的耐磨性、耐蚀性获得了明显提高，离子探针检测证实，稀土元素镧也渗入了钢的表面，起到了微合金化的作用。     

碳氮马氏体和含氮马氏体在回火过程中的硬度变化

测试了２０Ｃｒ２Ｎｉ４Ａ钢８２０℃碳氮共渗层中的碳氮马氏体低温回火时的硬度变化和工业纯铁经６８０℃氮碳共渗后渗层中的含氮马氏体回火过程中显微硬度的变化。     

AISI316奥氏体不锈钢低温PC、PN和PC+PN表面硬化处理

对AISI 31 6奥氏体不锈钢进行了低温离子渗碳 (PC)、离子渗氮 (PN)和离子渗碳 +离子渗氮 (PC +PN)双重复合处理 ,处理后的奥氏体不锈钢可以在不降低耐蚀性能的基础上大幅度地提高不锈钢表面硬度和耐磨性。渗入奥氏体晶格中的碳或 (和 )氮可以形成一种碳或 (和 )氮的过饱和固溶体 (S相 ) ,但没有铬的碳化物或 (和 )氮化物析出。由于PC +PN双重复合处理后的奥氏体不锈钢渗层内的最大含氮量位于渗层的外表面 ,而最大的含碳量则位于渗层较深的部位 ,因而经离子双重复合处理后的奥氏体不锈钢的表面既有离子渗氮处理的高硬度 ,又有离子渗碳处理后的高的渗层厚度和较好的硬度梯度等特点。     

离子碳氮共渗及复合处理的应用研究

采用氨气和丙酮作了源研究了４０Ｃｒ铜离子碳氮共渗和复合处理后组织性能,研究表明,离子碳氮共渗大幅度提高了表面硬度,耐磨性和抗咬合性能,还具有周期短,操作方便等特点,研究指出,复合处理不仅使表层得到较厚的渗层深度,较好的硬度梯度及残余应力状态,而且在较大负荷条件下显示出比离子碳氮共渗更优良的耐磨性,抗咬合性能,将试验结果用于轧辊,能显著提高使用寿命。     

低温固体硼碳氮稀土共渗及其机理探讨

研究了低温硼－碳－氮－稀土（Ｂ－Ｃ－Ｎ－ＲＥ）共渗工艺及共渗层的组织性能,并与硼－碳－氮（Ｂ－Ｃ－Ｎ）共渗工艺及共渗层的组织性能进行了比较,结果表明,低温共渗的硼化物层由ＦｅＢ、Ｆｅ２Ｂ、Ｆｅ３（Ｃ,Ｂ）等相组成,硼化物层的前沿无过渡区,ＦｅＢ和Ｆｅ２Ｂ生长过程中排挤出来的碳没有发生远程扩散,而是就近形成Ｆｅ３（Ｃ,Ｂ）等形式的硼化物。稀土加入量适当时,具有明显的催渗作用;与Ｂ－Ｃ－Ｎ共渗相比,Ｂ－Ｃ－Ｎ－ＲＥ共渗层的耐磨性和耐蚀性明显提高。对Ｂ－Ｃ－Ｎ－ＲＥ共渗的机理及稀土元素的作用作了初步的探讨。     

低碳钢与铝合金异种金属搭接激光-滚轮焊接

为了提高低碳钢与铝合金异种金属的焊接性能,采用激光-滚轮焊接工艺对低碳钢和铝合金搭接接头的焊接性能进行了研究,通过试验确定最佳工艺参数.采用激光显微镜和拉伸试验机分别分析了焊接接头组织和拉伸剪切性能.结果表明,随着激光功率的减少或焊接速度的增加,金属间化合物层厚度和接合宽度随之减小.随着滚轮压力的增加,金属间化合物层厚度随之增加.当金属间化合物层厚度为4～6μm,热输入量范围为375～800 J/cm时,拉伸剪切试样断裂位置均位于低碳钢母材侧.     

钎焊温度对SiC/YG8接头微观组织的影响

在保温时间为5min、钎焊温度为940~990℃条件下,采用CuMnNi钎料钎焊SiC陶瓷与YG8硬质合金.利用金相显微镜、扫描电镜和能谱仪对接头的微观组织进行分析,研究钎焊温度对接头微观组织的影响.结果表明:在靠近SiC一侧生成一层带状反应层,主要由Cu基固溶体、硅化物、碳和碳化物组成;焊缝主要由基底Cu基固溶体以及Mn、Si、Co、Cu、Ni元素形成的化合物组成.随着钎焊温度的增加,焊缝的宽度减少,焊缝中心的Cu基固溶体基底减少,而化合物相增多.     

Microstructure and properties of SiC gradiently coated Cf/C composites prepared by a RCLD method

The SiC gradiently coated carbon fiber/carbon (Cf/C) composites were prepared by a two-step rapid chemical liquid depo-sition (RCLD) method. The microstructure and properties of the composites were investigated using X-ray diffraction, scanning elec-tron microscopy together with energy dispersive X-ray analysis, bending tests, and oxidation tests. The experimental results show that the surface layer of the composites is composed of SiC, pyrocarbon, and carbon fibers. Their inner area consists of pyrocarbon and carbon fibers. The SiC content gradiently decreases with increasing distance from the outer surface to the center of the compos-ites. Furthermore, the thickness of the SiC layer increases with increasing tetraethylorthosilicate content and deposition time. SiC coatings have no significant influence on the bending strength of the composites. However, the oxidation resistance of the compos-ites increases with increasing thickness of the SiC layer.     

Preparation of expanded graphite-based composites by one step impregnation

A new method for preparing expanded graphite-based composites (EGCs) was developed.The obtained samples were characterized by scanning electron microscopy (SEM),transmission electron microscope (TEM) and nitrogen adsorption.The experimental results indicated that the EGCs was not simply mechanical mixture of EG and activated carbon,instead the activated carbon was coated on the surface of interior and external pores of the EG in the form of thin carbon layer.The thickness of the activated carbon layer was nearly one hundred nanometers by calculation.It was shown that the higher the impregnation ratio and the activation temperature were,the easier the porosity development would be.And the BET surface area and the total pore volume were as high as 1978 m2/g and 0.9917 cm3/g respectively at 350℃ with an impregnation ratio of 0.9.     

生长温度和源氛浓度对ZnO晶体生长影响的机理分析

利用原子层沉积（ALD）方法在Si（100）片上沉积200nm的ZnO薄层作为籽晶层,通过化学气相沉积（CVD）法常压下在籽晶层上生长ZnO晶体结构。通过X射线衍射（XRD）、场发射电子扫描显微镜（FESEM）和光致发光光谱（PL）手段对其结构形貌及光学性质进行表征,结合晶体生长机理讨论和分析影响ZnO微纳结构生长的因素。结果表明,反应源气氛浓度是影响ZnO形貌的重要因素。     

Synthesis of aligned carbon nanotubes by thermal chemical vapor deposition

Single crystal silicon was found to be very beneficial to the growth of aligned carbon nanotubes by chemical vapor deposition with C₂H₂ as carbon source. A thin film of Ni served as catalyst was deposited on the Si substrate by the K575X Peltier Cooled High Resolution Sputter Coater before growth. The growth properties of carbon nanotubes were studied as a function of the Ni catalyst layer thickness. The diameter, growth rate and areal density of the carbon nanotubes were controlled by the initial thickness of the catalyst layer. Steric hindrance between nanotubes forces them to grow in well-aligned manner at an initial stage of growth. Transmission electron microscope analysis revealed that nanotubes grew by a tip growth mechanism. Funded by the National Natural Science Foundation of China (No. 50435030)     

中碳结构钢表面P-C法改性层的耐热性

为了提高中碳结构钢的耐热性,应用Ｐ－Ｃ法进行复合表面涂覆,获得了Ｃｒ－Ｓｉ－Ａｌ复合表面改性层,研究了涂覆温度及时间对涂层表面成分的影响,确定了最佳的涂覆工艺参数,用电子探针及能谱测定了涂层的表面成分,用Ｘ射线测定了涂层中的相结构,将涂覆后的试样在空气介质中进行高温氧化试验,结果表明,由Ｐ－Ｃ法涂覆形成的表面改性层在这是质中具有优良的抗高温氧化性能。     

两段复合化学热处理新工艺的研究及应用

用含有碳氮的有机物做化学热处理渗剂,不仅可进行低温软氮化,还可进行中温碳氮共渗,若把两者联合起来,便可使钢件具有合理的渗层深度,金相组织和优异的耐磨性能,抗疲劳性能等。该复合工艺比每个单独工艺适用范围广,设备简单、操作方便,既节能又节时,是一种很有推广价值的工艺方法。     

Damping behaviors of metal matrix composites with interface layer

A novel technique of designing the interface layer in metal matrix composites of high damping capacity was developed via different CVD coatings on carbon fibers in Cc/AI composites. It was shown that the interface layer improved the tensile strength, elastic modulus and damping capacity of the Cf/AI composites. A carbon layer showed the highest improvement and a silicon layer the lowest, while a mixed carbon and silicon layer exhibited an intermediate effect. Moreover, the thickness of interface layer also influences the damping capacity. A thicker carbon layer produced a better damping capacity because the dependence of damping capacity on strain amplitude was increased. It is suggested that a micro-sliding action occurring in the interface layer is the main mechanism responsible for the high damping capacity of the composites.