石油化学阀门激光熔覆层凝固组织控制的研究

用5kW横流CW CO2激光器在1Cr18Ni9Ti与Cr18Ni12Mo3Ti阀门零件上熔覆NiCrFeBSi合金，得到了厚2～3.5mm、表面平整光滑和组织细密的合金熔覆区，并结合熔覆试验分析探讨了激光熔覆层快速凝固过程中的凝固组织及组织控制方法。     

柱塞Co基粉末激光熔覆工艺研究

为增强1Cr18Ni9Ti不锈钢零件的硬度及耐磨性,采用激光熔覆技术在其表面制备Co基合金熔覆层。利用光学显微镜,分析了熔覆层的微观组织;应用显微硬度计测试了熔覆层的硬度;应用浓度为2%的硝酸溶液做腐蚀剂,测试了熔覆层的耐腐蚀性。并与等离子热喷涂、Ni基合金熔覆等其它表面改性技术进行比较,结果表明:1Cr18Ni9Ti不锈钢柱塞Co基合金激光熔覆层硬度达到HV520,具有较好的耐磨性,其抗酸腐蚀性能也达到检验标准要求。     

钛合金表面NiCrBSi激光熔覆层的组织与耐磨性研究

在 TC4合金表面进行了激光熔覆 Ni Cr BSi涂层的试验 ,结果表明 ,激光熔覆层在微观结构上存在熔覆区、结合区和基体热影响区三个区域。熔覆区的组织是在初晶 γ Ni和 γ Ni、Ni3B、硅化物组成的多元共晶基底上分布着 Ti B2 、Ti C、M2 3( CB) 6等颗粒增强相。结合区是熔覆材料 Ni基合金和基体钛合金的混熔区 ,呈定向凝固特征。基体热影响区为针状马氏体组织。激光熔覆层的耐磨性能比时效硬化的钛合金显著提高 ,磨损机制是剥层磨损和磨粒磨损。     

核阀密封面激光熔覆层稀释率控制研究

采用5KW横流CO2激光器对1Cr18Ni9Ti核阀密封面进行了Co基合金激光熔覆处理，测定了激光熔覆层的受基体成分稀释的稀释率，并将其微观组织形貌、稀释率与等离子喷焊处理的同种试件进行了对比分析，结果表明：在保证与基体良好冶金结构的条件下，激光熔覆层的稀释率远小于等离子喷焊层，激光熔覆层还具有组织细密、晶粒度高和硬度高的特点，进而分析探讨了对激光熔覆层的稀释率控制。     

NiCrSiB合金高功率激光送粉熔覆裂纹形成的敏感因素

用 4 5k W高功率激光器对 Ni Cr Si B合金在送粉激光熔覆下裂纹形成的材料成分、熔覆工艺、微观组织等因素进行研究。实验表明 ,裂纹是由于熔覆层中大量的多种硬质相以及硬质相的不良分布形态所造成的高脆性 ,难以承受熔覆过程产生的较大拉应力所致。解决激光熔覆层裂纹问题的主要方向应是从工艺上降低熔覆过程的残余拉应力 ,同时从成分搭配和快速凝固特性上使得 Ni Cr Si B熔覆层微观组织中的硬质强化相细小均匀地弥散析出 ,保证熔覆层的高强度和高塑性     

添加Mn、Mo、Ti合金元素对激光熔覆WC-FeNiCr复合涂层组织及磁性能的影响

研究了添加Mn、Mo、Ti合金元素对激光熔覆Fe Ni Cr+60%WC复合熔覆涂层微观组织和磁性能的影响。利用扫描电子显微镜(SEM),能谱仪(EDS),X射线衍射仪(XRD)对熔覆层进行微观组织、成分及物相分析。利用振动样品磁强计(VSM)对熔覆层的磁性能进行测试。研究结果表明激光熔覆WC-Fe Ni Cr复合涂层与基体具有良好冶金结合,表面无裂纹、气孔等缺陷。Mn、Mo、Ti合金元素的加入,使得复合涂层冶金反应及组织形貌更加复杂,Fe、Ni、Cr元素之间存在相互作用并与WC之间存在互熔扩散,并生成了新的无磁相Ti C,Mo C,Fe-Cr(σ相),Cr0.19Fe0.7Ni0.11,而且Mn、Mo、Ti合金元素的加入使复合涂层相对磁导率显著降低,复合涂层磁性能具有较强的稳定性。     

OE工业激光及其应用

激光熔覆 Ni Cr Al-陶瓷涂层的磨损性能和显微组织研究陈庆华　龙晋明　魏　仑(昆明理工大学材料与冶金工程学院材料系 ,昆明 65 0 0 93)运用激光熔覆技术和原位反应合成的原理 ,在 4 0 Cr钢表面用预置涂层的方法 ,制备了 (Ti O2 + B2 O3+Al2 O3+ Ti B2 ) / Ni Cr Al金属陶瓷涂层。借助光学显微镜、X射线衍射仪、电子探针及显微硬度计等手段对熔覆层的组织、物相、元素分布和显微硬度分布特征进行了分析研究。实验表明 ,熔覆过程中同时原位生成 Ti B2 和 Al2 O3亚微米颗粒 ,原位生成的两个陶瓷相都以弥散的方式存在于 Ni Cr Al晶…     

激光熔覆镍基涂层的组织与磨损特性

利用大功率激光在1Cr18Ni9Ti表面熔覆NiCrBSi涂层,采用SEM、EDS和MM2000磨损试验机研究了不同激光功率下熔覆层的显微组织、成分及磨损特性.结果表明,熔覆层由熔覆区和结合区两部分组成,熔覆区主要有γ-(Ni,Fe)、CrB等多种相结构,呈现出树枝晶、不规则颗粒状、针状及共晶形式等多种形貌.结合区为细小柱状晶,激光功率增大,稀释率增大.熔覆层的磨损为磨粒磨损和粘着磨损共同作用的结果,磨损率分布在(2.2～2.6)×10-5 mm3/m.N之间,平均摩擦系数为0.52.激光功率增加,耐磨性下降.EDS分析表明主要元素Ni、Fe、Cr、Si在熔覆层中均匀分布.高功率激光熔覆层中,Fe含量所占比重明显增加.     

激光表面熔覆层凝固组织特征形成过程

试验研究了激光熔覆层的凝固特征和组织形成规律.结果表明:熔覆层不同位置的凝固特征参数不同.熔覆层底部属于典型的平面外延生长组织,且枝晶粗大;而顶部是较规则的树枝状共晶组织;中部为细小的胞晶和柱状晶;且晶体生长受结晶学各向异性影响.熔覆层组织晶粒形核的非均匀形核特征显著.熔覆层微区成分存在着不均匀性,不同元素沿晶间偏析(富集),是组织不均匀的重要原因.     

激光表面熔覆层凝固组织特征形成过程

试验研究了激光熔覆层的凝固特征和组织形成规律.结果表明:熔覆层不同位置的凝固特征参数不同.熔覆层底部属于典型的平面外延生长组织,且枝晶粗大;而顶部是较规则的树枝状共晶组织;中部为细小的胞晶和柱状晶;且晶体生长受结晶学各向异性影响.熔覆层组织晶粒形核的非均匀形核特征显著.熔覆层微区成分存在着不均匀性,不同元素沿晶间偏析(富集),是组织不均匀的重要原因.     

Probing film solidification dynamics in polymer photovoltaics

Semiconducting conjugated polymers have drawn a great deal of attention over the past decade due to their solution processability and potential use in roll to roll fabrication of organic solar cells. Here, we report the effect of solvent vapor pressure on poly(3-hexylthiophene):[6,6]-phenyl C₆₁-butyric acid methyl ester (P3HT:PCBM) blade coated inverted solar cells using ZnO as the electron transporting layer and MoO₃ as the hole transporting layer. The resultant morphology and device performance are investigated for devices processed from solvents with varied vapor pressure and a mixed solvent. We report that the use of a mixed solvent system is advantageous for controlling the initial vapor pressure of the processing solution, thereby controlling the phase separated morphology between P3HT and PCBM which impacts ultimate solar cell performance.     

炸药熔铸过程数值模拟研究

采用数值模拟方法研究了熔铸炸药常压和加压条件下凝固过程中的温度场,得到了温度的冷却曲线、固液界面的变化过程以及缩孔缩松缺陷可能出现的位置。常压条件下关注位置的计算温度值与实测温度值误差在10%以内;加压在5~20个大气压之间时,随着压力的增大,炸药件的缩孔缩松缺陷显著减少。模拟结果表明加压凝固工艺能有效地消除熔铸炸药的缩孔缩松缺陷。     

Phase equilibria and solidification properties of Sn-Cu-Ni alloys

Ternary Sn-Cu-Ni alloys were prepared and annealed at 240°C. The annealed alloys were metallographically examined and the equilibrium phases formed were identified on the basis of compositional determinations and x-ray diffraction (XRD) analysis. The isothermal section of the ternary Sn-Cu-Ni system at 240°C was proposed on the basis of experimental results of this study and related information on phase equilibrium available in the literature. The binary compounds, Cu₆Sn₅, Ni₃Sn₂, and Ni₃Sn₄, have very extensive ternary solubility. Continuous solid solutions form between Cu and Ni as well as between Cu₃Sn and Ni₃Sn. In addition to the isothermal section, the liquidus projection of the Sn-Cu-Ni system was determined based on results from the existing literature. Interfacial reactions between Sn-Cu alloys and Ni substrate and the primary solidification phases of various Sn-Cu-Ni alloys were also examined in this study.     

Equilibrium solidification of Sn-Ag-Sb thermal fatigue-resistant solder alloys

A survey of the liquidus surface and invariant reactions involving liquid has been made for solidification in the ternary Sn-Ag-Sb system. Differential thermal analysis and electron-beam microprobe analysis were used to measure liquidus temperatures and determine the composition of solid phases resulting from solidification. A liquidus projection and the composition of the phases coexisting at the two observed invariant reactions were determined. Ternary alloys based on the Sn-Ag-Sb system have been used as thermal fatigue-resistant solders where high heat loads must be dissipated. An analysis of the properties encountered from such solders is presented, based on the phase constitution resulting from the solidification behavior reported here. We wish to acknowledge the contribution of pure metals used in this research, as well as support and advice, by Cominco Electronic Materials of Spokane, Washington.     

Sequential lateral solidification processing for polycrystalline Si TFTs

The sequential lateral solidification (SLS) process is an excimer-laser projection-based scheme for crystallization of thin films on amorphous substrates. This method can be used to readily produce a wide range of microstructures through manipulation of grain boundary placement within the crystallized material. In this paper, we focus on the 2-shot SLS process for crystallization of thin Si films for thin-film transistor (TFT) applications. We have investigated the effect of process parameter variation on the resulting microstructure, as well as on the performance of TFTs fabricated on the material. The 2-shot SLS microstructure was further engineered to reduce anisotropy of the TFT performance relative to the lateral growth direction using additional laser scans. Through this method, we were able to improve the mobility directionality ratio between devices with majority carrier flow parallel and perpendicular to the lateral growth direction, respectively, from 0.3 to over 0.7. Post-SLS process thinning and planarization of the Si surface was used to improve the uniformity and performance of the TFT devices.     

Primary solidification phases of the Sn-rich Sn-Ag-Cu-Ni quaternary system

The eutectic and near-eutectic Sn-Ag-Cu solders are the most promising lead-free solders, and nickel is frequently used as the barrier layer material. Nickel dissolves into the molten Sn-Ag-Ni alloy during the soldering process, and the ternary solder becomes a Sn-Ag-Cu-Ni quaternary melt near the nickel substrate. Liquidus projection is the projection of the liquidus trough and it delineates the boundaries of various primary solidification phases. Information of liquidus projection is helpful for understanding the alloys’ solidification behavior. This study prepared the Sn-Ag-Cu-Ni alloys of various compositions at the Sn-rich corner. The alloys were melted at higher temperatures and solidified in air. The solidified alloys were metallographically examined to determine the phases formed, especially the primary solidification phases. No ternary or quaternary compounds were found. The knowledge of the primary solidification phases, phase formation sequences, and reaction temperatures determined in this study were put together with all of the available liquidus projections of the constituent ternary systems to determine the primary solidification phases of the quaternary Sn-Ag-Cu-Ni system at the Sn-rich corner.     

Die bonding with Au/In isothermal solidification technique

A gold-indium isothermal solidification technique has been developed for die bonding. Both silicon on silicon and silicon on alloy 42 (chip size 2 × 2 mm²) are investigated. For silicon on silicon, the bonding is performed at 200°C within 30 sec. The bonds can withstand 1,500 cycles of temperature cycle between −65°C and 150°C without any degradation. For silicon on alloy 42, the bonding is done at 250°C within 5 sec. The bonds can pass the shear strength test specified by MIL STD 883D, Method 2019.5. The reliability of the bonds is evaluated by thermal cycle testing. After 500 cycles between −65°C and 150°C, only slight degradation was observed.     

High-performance ultralow-temperature polycrystalline silicon TFT using sequential lateral solidification

This letter presents technologies to fabricate ultralow-temperature (< 150 /spl deg/C) polycrystalline silicon thin-film transistor (ULTPS TFT). Sequential lateral solidification is used for crystallization of RF magnetron sputter deposited amorphous silicon films resulting in a high mobility polycrystalline silicon (poly-Si) film. The gate dielectric is composed of plasma oxidation and Al/sub 2/O/sub 3/ grown by plasma-enhanced atomic layer deposition. The breakdown field on the poly-Si film was above 6.3 MV/cm. The fabricated ULTPS TFT showed excellent performance with mobility of 114 cm/sup 2//V /spl middot/ s (nMOS) and 42 cm/sup 2//V /spl middot/ s (pMOS), on/off current ratio of 4.20 /spl times/ 10/sup 6/ (nMOS) and 5.7 /spl times/ 10/sup 5/ (pMOS), small V/sub th/ of 2.6 V (nMOS) and -3.7 V (pMOS), and swing of 0.73 V/dec (nMOS) and 0.83 V/dec (pMOS).     

Wafer level hermetic packaging based on Cu-Sn isothermal solidification technology

A novel wafer level bonding method based on Cu-Sn isothermal solidification technology is established. A multi-layer sealing ring and the bonding processing are designed, and the amount of solder and the bonding parameters are optimized based on both theoretical and experimental results. Verification shows that oxidation of the solder layer, voids and the scalloped-edge appearance of the Cu6Sn5 phase are successfully avoided. An average shear strength of 19.5 MPa and an excellent leak rate of around 1.9 × 10-9 atm cc/s are possible, meeting the demands of MIL-STD-883E.