送粉激光熔覆熔池深度解析模型的误差分析

系统分析了送粉激光熔覆熔池深度解析模型的误差。揭示了解析模型建立过程中粉末颗粒运动的物理模型的选择、激光与熔覆材料及基体材料作用效率的计算、材料对激光的吸收系数的测定、相关参数的检测是误差产生的主要原因。探讨了减小误差的方法。     

Mechanism of laser beam welding for SiCp／6063Al composite

The laser beam welding technique was used to process SiC particles/6063A1 alloy matrix composite, the influence of laser power and welding speed on the properties of joint was studied. Decreasing the laser beam power with same welding speed can make the quantity and size of A14C3 decreased, and the interactive mechanism of the reinforcing particles and the matrix in the joint and the causes for joint strength reduction were analyzed.Increasing welding speed properly can improve the distribution of energy and restrain the interfacial reaction in the molten pool, and measures for improving were proposed.     

高岭土熟料对焙烧后石膏混合科组织及性能的影响

本丈对以高岭土熟料为填料的石膏混合料作了一系列试验研究。用扫描电镜观察了不同焙烧温度下,试样断口显微结构的变化过程;探索了焙烧温度对石膏混合料抗弯强度、线收缩率的影响;揭示了显微结构与性能之间的内在联系;搞清了随着焙烧温度升高,高岭土填料在改善石膏混合料性能方面的作用机理。关键词:石膏型填料高岭土熟料焙烧性能     

LY12CZ材料激光辐照延寿的微观研究及损伤演变

对激光辐照后Ly12 CZ铝合金的疲劳寿命明显提高的原因进行了微观研究。结果表明位错胞尺寸λ在疲劳失效时都趋向于一常量λ_c。结合损伤力学建立了该材料的疲劳损伤判据及损伤演变过程,分别为: D_c=1-(λ_c/λ_0)~P D=1-{1-[1-(λ_c/λ_0)~(P(1+γ))](N/N_f)}~(1/(1+γ)     

间接选择性激光烧结与选择性激光熔化对比研究

采用选择性激光烧结（Selective laser sintering，SLS）和选择性激光熔化（Selective laser melting，SLM）工艺，分别进行了铁基合金粉末的快速成形试验，对比分析了SLS与SLM成形机理、相应的工艺参数以及它们对测试件成形过程、金相组织与力学性能的影响。结果表明：由于成形机理不同，相对于SLS技术，采用SLM能够制造高致密度、组织均匀、力学性能良好的金属零件，但容易出现翘曲变形、裂纹与球化现象。通过制定合适的材料与工艺参数能够避免上述缺陷。     

滴注式气体渗碳全脉冲信号控制研究

提出了滴注式气体渗碳采用全脉冲信号控制方式，并对其抗干扰性能和控制精度进行了分析，它能明显提高系统的控制精度和抗干扰性能。     

EFFECT OF RARE EARTH ELEMENT Er ON STRENGTHENING OF INTERFACE OF Ti（C，N） BASED CERMETS

ＥＦＦＥＣＴＯＦＲＡＲＥＥＡＲＴＨＥＬＥＭＥＮＴＥｒＯＮＳＴＲＥＮＧＴＨＥＮＩＮＧＯＦＩＮＴＥＲＦＡＣＥＯＦＴｉ（Ｃ，Ｎ）ＢＡＳＥＤＣＥＲＭＥＴＳ￥ＬｉｕＮｉｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｅｒｉａｌｓＳｃｉｅｎｃｅａｎｄＥｎｇｉｎｅｅｒｉｎｇ，...     

Microstructures and Properties of Laser-Glazed Plasma-Sprayed ZrO2-YO1.5/Ni-22Cr-10AI-1Y Thermal Barrier Coatings

Thermal barrier coatings (TBCs) consisting of two layers with various yttria contents (ZrO ₂- YO_1.5/Ni-22Cr-10Al- lY) were plasma sprayed, and parts of the various specimens were glazed by using a pulsed CO₂ laser. All the specimens were then subjected to furnace thermal cycling tests at 1100 °C; the effect of laser glazing on the durability and failure mechanism of the TBCs was then evaluated. From these results, two models were developed to show the failure mechanism of as- sprayed and laser- glazed TBCs: model A, which is thermal-stress dominant, and model V, which is oxidation-stress dominant. For top coats containing cubic phase, cubic and monoclinic phases, or tetragonal and a relatively larger amount of monoclinic phases, whose degradation is thermal- stress dominant, laser glazing improved the durability of TBCs by a factor of about two to six. Segmented cracks that occurred during glazing proved beneficial for accommodating thermal stress and raising the tolerance to oxidation, which resulted in a higher durability. Thermal barrier coatings with top coats containing tetragonal phase had the highest durability. Degradation of such TBCs resulted mainly from oxidation of the bond coats. For top coats with a greater amount of monoclinic phase, thermal mismatch stress occurred during cooling and detrimentally affected durability.     

等离子显示器(PDP)用BaMgAl10O17:Eu2+蓝粉的烧结工艺研究

研究了烧结温度、保温时问以及粘结剂对荧光粉二次性能的影响。结果表明，当采用较低烧结温度时，有机粘结剂没有完全分锵是造成荧光粉亮度下降的主导因素，包覆在荧光粉表面的残留部分降低了荧光粉的表面光透率；当烧结温度升高，粘结剂的影响逐渐下降，而过高的烧结温度在导致荧光粉劣化各种因素之间起到了决定性的作用。在此基础上，依据对粘结剂中成膜物质乙基纤维素的降解特性的分析，对浆料烧结工艺进行了优化。结果表明，当浆料加热至480℃，有机粘结剂分解已趋于饱和，从而可以有效降低烧结工序对荧光粉的不利影响。     

微波场作用下Y2O2S：Tb绿色荧光粉的快速合成及其发光特性

采用微波法快速合成了Y2O2S：Tb绿色荧光粉。用X射线衍射（XRD）仪、扫描电镜（SEM）、荧光分光光度计等对合成产物的相结构、形貌、以及发光特性进行了研究。结果表明：材料的晶体结构为六方晶系，与Y2O2S相同。颗粒的形貌为类球形，分散性很好，平均晶粒尺寸在300nm左右。发射光谱由384，418，439，460，475，498，547，590，624nm等一系列窄带发射峰组成，归属于Tb^3＋从^5D3，^5D4到^7FJ（J=0～6）的跃迁。研究发现Tb的掺杂浓度对样品的发射光谱有着很重要的影响，当其浓度为0．5％（摩尔分数，下同）时，^5D3→^7FJ的蓝光发射发生猝灭，当其浓度为9％时，^5D4→^7FJ的绿光发射发生猝灭。