CVD金刚石膜热沉表面金属化

提出一种金刚石膜热沉表面金属化新工艺。该工艺采用Ti Ni Au体系和电子束真空镀膜方法 ,并经过金刚石膜预处理和后续低温真空热处理获得了良好的结合性能。研究表明 :预处理对金属层和金刚石膜的结合强度影响显著 ,结合强度由原来的 1 4 0MPa提高到 48 9MPa ;金刚石膜 Ti Ni Au经过 1 0 0次从 2 0 3K到 42 3K冷热循环 ,金属和金刚石膜之间没有发现脱膜现象。XRD进一步证实 :经过后续 673K× 2h低温真空热处理 ,Ti 金刚石膜界面形成TiO和TiC。Ti和金刚石膜之间的扩散与反应产物不仅取决于反应温度 ,还和金刚石膜表面状态有关     

CVD金刚石膜散热性能的实验及仿真分析

本文基于化学气相沉积(CVD)金刚石膜的超高热导率,设计并搭建了一套实验系统,分析其对于小空间高热流密度电子元件的散热效果。通过测量加热器及材料表面的温度值可知,相同工况下,金刚石膜温度梯度小,温度分布均匀性好,表面最大温差仅为铜的一半且加热面温度相比于铜更低。实验结果说明CVD金刚石膜的散热性能明显优于传统散热材料铜。实验验证了经过Ti-Ni-Au金属化处理的CVD金刚石薄膜具有可焊性。在实验基础上,利用Flotherm软件对系统进行仿真建模,进一步探讨了材料厚度、热导率及接触热阻对加热面温度和最大热流密度的影响。     

CVD金刚石切削工具

CVD金刚石不含任何金属或非金属添加剂，机械性能兼具单晶金刚石和聚晶金刚石(PCD)的优点，而又在一定程度上克服了它们的不足。大量实践表明，焊接型CVD金刚石工具的使用寿命大大超过聚晶金刚石工具，有几乎相同的硬度和耐磨性，其抗冲击性优于单晶金刚石膜。因此，CVD金刚石被认为是非铁材料加工业中最理想的工具材料。据预测，在二、三年内，CVD金刚石工具将逐步代替天然金刚石工具以及目前已使用了二十多年的PCD工具，从而大大提高生产效率，降低生产成本。     

CVD金刚石磨损性能的研究

提出了一种直接评价CVD金刚石磨损性能的实验方法,比较研究了热丝CVD法、微波等离子体CVD法和直流电弧等离子体CVD法制备的金刚石的磨损性能。研究结果表明:影响CVD金刚石磨损性能的主要因素是非金刚石相的相对含量,金刚石的内应力和晶粒大小对磨损性能的影响较小。     

CVD金刚石膜的抛光研究进展

化学气相沉积的金刚石膜表面一般比较粗糙,需要经过抛光才能实现其具体的工业应用。本文介绍了各种抛光CVD金刚石膜的方法及近来研究进展,分析了各种技术的优缺点,并结合工业应用对CVD金刚石膜的抛光前景作了展望。     

CVD金刚石磨耗比测定

磨耗比是表征CVD金刚石耐磨性的重要参数,通常按照JB/T3235-1999标准进行测定,本文介绍了一种改进的测量方法,并就测量参数对结果的影响进行了研究.该方法采用的测量装置结构紧凑、操作简便而且运行稳定,对操作环境无特殊要求;实际测试过程中,考虑到测试的参量易获得性和测量的便捷性,仅通过变频调速器固定砂轮的初始线速度,不再中途停机调整线速度,车削量以控制车削次数为准,通常在180次后停止,遇到磨耗比数值偏高时,也可适当增加车削次数;测量金刚石的磨耗量时采用体积法,得到的测量结果的重复性较好.采用此测试方法进行CVD金刚石磨耗比测定,不但缩短了测试周期,而且提高了磨耗比测量数据的准确性,为生产工艺控制提供了重要依据.     

CVD金刚石薄膜及膜-基界面形态

采用直流等离子体财流CVD法在硬质合金基体上沉积了多晶金刚石薄膜,借助XRD、Raman光谱、SEM和EPMA等对金刚石薄膜及膜-基界面的结构、形貌和成分进行了研究.结果表明,结晶度高的刻面型金刚石薄膜质量、纯度较好,膜-基界面处较致密,机械锚固作用明显,结合性能较好沉积前后基体表面形貌变化很大,存在数十微米厚的脱钴-等离子体刻蚀层,等离子体刻蚀导致脱钻表面更加凹凸不平,为金刚石形核提供了有利条件.     

利用热等离子体CVD工艺合成大面积金刚石薄膜

CVD金刚石可以用各种方法合成，其中晶粒生长速度最快的则为热等离子体CVD工艺。我们试验室过去曾试图用DC等离子体CVD工艺合成金刚石厚膜，并就膜与基底的附着强度和膜的性质作过探讨。但是，热等离子体工艺存在沉积面积和膜质量都不如其它CVD工艺等问题。CVD金刚石薄膜应用中对扩大沉积面积有着强烈的需求。本研究试图通过控制沉积压力、输入功率等沉积参数扩大等离子体直径，以沉积出大面积金刚石薄膜。我们的目的是利用热等离子体CVD工艺沉积出生长速度高、面积大且膜厚均匀的金刚石薄膜。同时探讨了合成条件对金刚石薄膜形状的影响。本研究得出的结果如下：(1)随着沉积压力的降低，金刚石晶粒尺寸减小，成核密度增加。金刚石的结晶性则几乎不受沉积压力的影响。(2)随着等离子体电流的增加，金刚石晶粒尺寸减小，成核密度增加。增加等离子体电流也可改善金刚石的结晶性。(3)降低沉积压力和增加等离子体电流均可扩大等离子体射流，但是金刚石沉积面积的变化并不明显。(4)随着沉积压力的降低和等离子体电流的增加，金刚石的结晶性均会增加。降低沉积压力和增加等离子体电流有利于改善金刚石薄膜的均匀性。     

CVD金刚石膜将成为金刚石材料未来发展的主流

1．引言 化学气相沉积CVD金刚石薄膜是继动态与静态法合成金刚石后,出现的一种与前两种方法完全不同的方法。按照传统的金刚石合成机制,用这种方法也能合成金刚石,简直让人不可思议。可是用这种方法合成出了金刚石已是不争的事实。     

CVD金刚石拉丝模花丝成因研究

通过分析CVD金刚石拉丝模和单晶金刚石拉丝模的显微照片，发现CVD金刚石的晶界和内部缺陷是造成使用CVD金刚石拉丝模比使用单晶金刚石拉丝模“花丝”现象更严重的原因。     

Fabrication, microstructure and properties of SiCp/Cu heat sink materials

Cu-coated powder was fabricated by electroless plating process, and the composition and morphology of coated powder were studied.Moreover, Cu-30, 40, 50 vol.%SiCp heat sink materials were fabricated by hot pressing using coated and uncoated powder.And the microstructure and thermophysical properties of the heat sink materials were also studied.The results show that SiCp particles distribute uniformly in heat sink materials and the interface between SiCp particles and Cu matrix is clear and well bonded.On the condition of same volume fraction of SiCp, the thermal conductivity of the material using coated powder is larger than that of the material using uncoated powder.Under experiment conditions, the thermal conductivity and coefficient of thermal expansion of Cu-30 vol.%SiCp heat sink material is 236.2 W·m-1·K-1 and 9.9×10-6/K (30-200 ℃) respectively.It provides important reference data for future experiments.     

6082铝合金散热器精锻工艺分析及模具设计

分析了汽车用6082铝合金散热器的精锻成形工艺,利用Deform-3D软件对其成形过程进行模拟,结合成形过程中金属的流动规律分析,提出合理的模具设计方案。经试模生产验证,该工艺方法合理,产品质量稳定。     

610MPa级大热输入高强钢焊接性能热模拟研究

利用Gleeble1500热模拟试验机研究了610 MPa级高强度钢板在60～120 kJ/cm热输入下的焊接热影响区性能,分析了影响焊接性能的显微结构因素。试验结果表明:试验钢在60～100 kJ/cm的大热输入焊接热模拟后拉伸强度和低温韧性良好,而在120 kJ/cm大热输入下机械性能下降较大但仍满足要求;试验钢中大量弥散分布的细小TiN粒子在热循环过程中能够钉扎奥氏体晶界和促进铁素体晶内形核,能有效抑制热影响区组织长大,保证了试验钢的大热输入焊接性能。     

Improvement of heat resistance of high performance fibers using a cold plasma polymerization process

The aim of this work consisted in improving the heat barrier efficiency of different nonwovens (NW) to protect metallic substrates. The degradation of NW based on phenolic, melamine, polyacrylate, meta-aramid and polyimide fibers has been investigated by thermogravimetric analyses while the heat resistance of the NW has been evaluated by measuring temperature profiles in a heat radiator test. In order to decrease the surface emissivity and protect the fibers, a tetramethyldisiloxane (TMDSO) based plasma polymer has been coated on the NW surfaces using a Plasma Enhanced Chemical Vapor Deposition (PECVD) treatment. The plasma polymer has been characterized: it is composed of polysiloxanes, and the deposit coats homogeneously the surface fibers. Heat radiator tests carried out on the coated NW show that the organosilicon coating allows in most of the cases (phenolic, polyacrylate, meta-aramid and melamine NW) an effective improvement of the heat barrier effect under a radiative heat flux. The structural integrity of the NW under heating is improved as well, except in the case of polyimide based NW fabrics.     

Laser transformation hardening of carbon steel sheets using a heat sink

A heat-sink assisted laser transformation hardening method is presented as a way to enhance the hardenability of carbon steel sheets. In this study, the thermal conductivity of the heat sink and the thermal contact resistance between the steel sheet and the heat sink were identified as the two primary parameters for the process. Using a process map approach, the heat-treatability of steel sheets was studied theoretically focusing on carbon diffusion and cooling time characteristics. For validation purposes, 2 mm thick DP 590 and boron steel sheets were laser-hardened using four types of heat sink: stainless steel, steel, copper, and no heat sink. Surface hardness, hardening width and depth were measured and analyzed over a wide range of process parameters. From this study, it was revealed that, when a heat sink is used, both cooling and carbon diffusion characteristics become roughly on par with those of the thick plate case, but the heat treatable region remains similar to that of the no heat sink case. The use of a heat sink was found to be an effective way of enhancing the hardenability of steel sheets and the amount of enhancement is largely proportional to the heat sink thermal conductivity.     

Study of the performance of TBC under thermal cycling conditions using an acoustic emission rig

An experimental rig based on the use of infrared quartz lamps has been developed to monitor the degradation mechanisms causing failure of thermal barrier coatings (TBC) under thermal-cycling conditions. An acoustic emission (AE) technique monitored these degradation mechanisms, and advanced signals processing identified the key parameters that classify the AE signals according to the long-term behavior of the TBC. The AE technique enabled the localization of degradation sources inside the TBC with a linear resolution of ∼5 mm by the use of two transducers fixed at both ends of the sample. Furthermore, sample zones of high AE activity showed typical vertical cracks at the surface and delaminations at the interface between the ceramic and the bond-coat layer. Vertical cracks were induced preferentially during the heating period of the thermal cycles when the ceramic coating was in a tensile-stress state, while delaminations were induced during the cooling period when the TBC was in a compressive-stress state.     

大功率发光二极管相变热沉的制造及测试(英文)

制造一种新型大功率发光二极管(LED)相变热沉作为封装级散热元件,采用犁切?挤压成形的周向螺旋状微沟槽和采用冲压成形的放射状径向沟槽组成的三维结构作为蒸发面强化沸腾结构,内壁采用铜粉颗粒烧结而成的毛细芯结构为工质提供循环动力。测试了相变热沉在不同输入功率和工质条件下的运行特性。结果表明,相变热沉具有良好的传热能力,在环境温度为20°C,输入功率为10W的条件下,相变热沉最高温度为86.8°C,可满足功率为10W的LED封装散热需求。     

3Cr2NiMo钢模块锻后热处理的数值模拟

以3Cr2NiMo模具钢锻造模块为研究目标,通过JMatPro软件计算获得其热物性参数,利用Deform-3D软件对其锻后热处理进行了数值模拟研究,最后进行了试验验证.结果表明:淬火过程中模块外表面的冷速大于心部;从心部到表面,马氏体转变出现不等时现象,淬火后从表面到心部的组织分布依次为马氏体、贝氏体和铁素体.等效应力...     

Fe3Al/18-8扩散焊接头热处理后组织性能的变化

采用不同的热处理工艺对FeAl／18—8扩散焊接头进行热处理,利用金相显微镜、扫描电镜(SEM)、X射线衍射仪(XRD)等测试手段对热处理后的组织性能进行了分析。试验结果表明：经过焊后热处理的FeAl／18—8扩散焊接头组织更加均匀,扩散过渡区中弥散分布有第二相析出物,合理的焊后热处理工艺为：加热温度800℃、保温时间30min、炉冷至700℃再空冷。热处理后FeAl／18—8扩散焊接头的显微硬度降低．没有出现高硬度脆性相。