微晶玻璃固结磨料研磨加工亚表面损伤预测研究

目的 快速、准确预测微晶玻璃在研磨加工过程中的亚表面损伤状况,制定合理的加工工艺。方法 通过建立微晶玻璃的离散元模型,仿真分析了研磨压力等研磨工艺参数对工件亚表面损伤的影响规律,并采用角度抛光法对研磨后微晶玻璃的亚表面损伤状况进行了实验验证。结果 采用W14金刚石固结磨料垫研磨微晶玻璃,当研磨压力为10 kPa时,工件亚表面裂纹层深度为1.75μm,当研磨压力降低至3.5 kPa时,工件亚表面裂纹层深度为1.38μm;随着研磨压力的降低,亚表面微裂纹数量减少。研磨残余应力层分布深度大于微裂纹层的,且在微裂纹的尖端存在较大的残余拉应力。结论 角度抛光法得到的亚表面裂纹层深度与仿真结果一致,偏差范围为-10.87%～11.29%,残余应力仿真结果与试验结果的偏差为7.89%。离散元仿真能够比较准确地预测固结磨料研磨微晶玻璃的亚表面损伤状况,为其研磨抛光工艺参数的制定提供了理论参考依据。     

固结磨料研磨蓝宝石晶片的工艺优化

为了满足蓝宝石晶片高效低损伤的加工要求,采用亲水性固结磨料研磨垫研磨蓝宝石晶片的工艺,研究基体中碳化硅粒度尺寸、基体类型、金刚石粒度尺寸及研磨液中磨料4个因素对材料去除率和表面粗糙度的影响,并综合优化获得高加工效率和优表面质量的工艺参数。实验结果表明:基体中碳化硅粒度尺寸为10 μm、基体类型为Ⅱ、研磨垫采用F公司粒度尺寸为35~45 μm的金刚石、研磨液中磨料的粒度尺寸为5 μm的碳化硅为最优工艺组合,亲水性固结磨料研磨蓝宝石的材料去除率为431.2 nm/min,表面粗糙度值为R_a 0.140 2 μm。      

易解理氧化镓晶片的半固结研磨工艺

目的 为了探究在半固结研磨工艺下的工艺参数对单晶氧化镓(100)晶面材料去除率和表面形貌的影响。方法 通过单因素试验研究研磨垫上磨料的粒度、研磨压力和研磨盘转速等工艺参数对氧化镓晶片材料去除率和表面粗糙度的影响规律,并采用正交试验对工艺参数进行优化。结果 实验结果表明,随着研磨垫上磨料粒度的增大,材料的去除率也逐渐增大,表面粗糙度也逐渐增大;随着研磨压力的增大,材料去除率逐渐增大,表面粗糙度增大的趋势逐渐减缓;随着研磨盘转速的增大,材料去除率逐渐增大,表面粗糙度变化不大。最后通过正交试验优化了工艺参数,得到优化后的最佳工艺组合,研磨垫上磨料的粒度为3μm,研磨压力为2940 Pa,研磨盘转速为60 r/min,研磨后氧化镓表面粗糙度为26 nm,材料去除率为3.786 nm/min。结论 半固结研磨工艺可以抑制解理现象,并且通过选择合适的半固结研磨工艺参数能够稳定有效地降低表面粗糙度,获得较好的氧化镓表面,并为后续的精密抛光工艺提供了技术依据。     

固结磨料研磨K9玻璃亚表面损伤层深度测量方法研究

光学工件研磨后亚表面损伤层深度是确定其抛光加工余量的重要依据。采用三种典型的光学材料亚表面损伤层深度测量方法(BOE分步腐蚀法、BOE差动腐蚀法、磁流变抛光斑点法),测量比较了固结磨料研抛垫(FAP)研磨后K9玻璃的亚表面损伤层厚度;建立了亚表面损伤模型,分析比较测量误差产生的原因。结果表明:在实验条件下,BOE分步腐蚀法测量精度优于其他两种方法;BOE分步腐蚀法、磁流变抛光斑点法、BOE差动腐蚀法的测量精度分别约为0.1nm、17nm、200nm;亚表面损伤层总深度与其裂纹深度之间存在对数关系。     

固结金刚石聚集体磨料垫高效研磨氧化锆陶瓷背板

氧化锆陶瓷背板的高效低损伤研磨加工是其在5G通讯应用中的前提。针对氧化锆材料的硬脆特性造成磨粒磨损严重的特点,以金刚石单晶和聚集体为磨料,制备固结磨料垫（FAP）,并对比研究其加工性能,探索了研磨液中碳化硅磨粒在固结磨料研磨垫自修整过程中的作用机理。结果表明:采用金刚石聚集体作为固结磨料垫的磨料,辅以碳化硅砂浆,能够明显提高研磨速度,改善表面加工质量。采用粒度230/270的金刚石聚集体固结磨料研磨垫,辅以颗粒尺寸3~5 μm的绿碳化硅砂浆,氧化锆陶瓷研磨时材料去除率达2.5 μm/min以上,表面粗糙度值R_a为74.9 nm。      

石英玻璃固结磨料研磨工艺参数响应面模型的研究

目的 通过优化工艺参数,充分挖掘固结磨料研磨加工的优势.方法 采用固结磨料研抛垫对石英玻璃进行研磨,以材料去除率(MRR)和表面粗糙度(Ra)为评价指标,采用3因素3水平的响应曲面法,探索工件转速、研磨压力、研磨液流速三个工艺参数对固结磨料垫加工特性的影响规律.建立三个工艺参数作用下的MRR模型和Ra模型,结合响应曲面及其等高线,获得工艺参数变量两两复合的影响规律和各目标下的最优工艺参数.最后,对最优工艺参数进行实验验证.结果 实验结果及其分析表明,以最大材料去除率为目标的最佳工艺参数为:转速90 r/min,压力20.685 kPa,研磨液流速60 mL/min.以最小表面粗糙度为目标的最佳工艺参数为:转速100 r/min,压力20.685 kPa,研磨液流速80 mL/min.最优工艺的加工性能预测值为34.5 nm/min和38.5 nm,验证实验结果为37.6 nm/min和39.4 nm,二者的误差值在合理范围内.结论 研抛工艺参数的响应面模型具有良好的预测能力,预测误差很小,最优工艺参数下,工件表面平整光滑,没有明显的凹坑和粗大划痕.     

单晶蓝宝石高效超精密加工技术研究

针对光电子器件、集成电路等应用领域对单晶蓝宝石高质量的表面需求,而单晶蓝宝石自身的硬度和良好的化学稳定性给抛光带来较大的困难。文章在分析、对比直接采用2μm金刚石磨料化学机械抛光蓝宝石基片效果的基础上,提出机械研磨与化学机械抛光相结合的工艺抛光蓝宝石。结果表明,采用10μm的碳化硼磨料机械研磨蓝宝石,材料去除率为8.03μm/h,表面粗糙度Ra由1.18μm迅速降至22.326 nm;采用粒径为2μm和0.5μm的金刚石磨料化学机械抛光蓝宝石晶片,有效的去除机械抛光带来的损伤,最后表面粗糙度Ra可达0.55 nm。此抛光工艺能满足蓝宝石晶体高效、超光滑、低损伤的抛光要求。     

熔石英磨削的残余应力层深度预测研究

目的 磨削后工件表面残余应力处于裂纹层下方其位置隐蔽、不易检测，使用过程中受到应力作用易扩展成裂纹，影响后续工艺参数设计和工件使用寿命。因此，研究磨削后表面残余应力层深度有助于确定后续工艺加工余量，提高工件使用性能。方法 本文采用离散元法建立单颗磨粒磨削熔石英的离散元模型，研究磨粒粒径对工件亚表面损伤深度的影响。采用角度抛光法和差动腐蚀法测量熔石英亚表面裂纹层和损伤层深度，计算残余应力层深度并验证模型。结果 当磨粒粒径分别为7、14、28、40μm时，仿真得到的裂纹层深度分别为2.53、3.02、4.07、7.39μm，残余应力层深度分别为0.75、1.00、1.34、2.33μm；实验测得的裂纹层深度分别为2.51、3.14、4.65、8.16μm，残余应力层深度分别为0.86、0.93、1.31、1.87μm。由此可见，随着磨粒粒径的增大，工件表面的脆性去除愈加明显，表面质量变差，亚表面裂纹层深度和残余应力层深度增大。仿真预测裂纹层深度与实验值偏差小于15%，残余应力层深度偏差小于25%，残余应力层深度约为裂纹层深度的1/4～1/3，随磨粒粒径增大，比例逐渐减小。结论 离散元仿真可...     

砂浆辅助固结磨料研磨蓝宝石研究

金刚石固结磨料垫研磨蓝宝石晶片时,因磨屑细小导致研磨垫自修整能力严重不足,制约了其工业应用。本实验尝试用向研磨液中添加碳化硅颗粒的办法,辅助磨屑改善研磨垫的自修整能力。分别制备了不含磨料和含金刚石磨料（粒度尺寸为20~30 μm）的研磨垫,比较其在不同研磨条件下的材料去除率和研磨后工件表面形貌,探索研磨液中碳化硅颗粒的作用机制。结果表明:研磨液中添加的碳化硅颗粒加快了研磨垫基体的磨损,有利于亚表层金刚石颗粒的出露,实现了研磨垫的自修整过程,材料去除速率明显提高,提高近14倍。      

基于深度学习的固结磨料研磨垫表面形态表征

固结磨料研磨垫的表面形态与其加工性能有着密切关系,为更好地了解固结磨料研磨垫表面形态,尤其是研磨垫中的金刚石、孔隙、金刚石脱落坑等的分布特征,提出一种基于深度学习的固结磨料研磨垫表面形态分析方法。首先,利用徕卡DVM6数字显微镜及其配套软件获取固结磨料研磨垫表面图像;然后,采用python3+OpenCV对图像进行预处理,并利用标注软件Labelme对图像进行标注,用于后续的训练和测试;最后,运用深度学习框架Tensorflow搭建Mask R-CNN模型。结果表明:Mask R-CNN模型能对单一固结磨料垫表面图像中的多目标进行有效分割与识别,其主要评价指标平均准确率达到78.9%,达到了图像识别的主流水平。      

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Rheology Feature of Simple Metal Melt

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.     

Microstructures and Mechanical Properties of a Newly Developed Austenitic Heat Resistant Steel

The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX. Subsequent aging treatment causes the precipitation of M_(23)C_6 carbides along the grain boundaries and a small number of nanoscale MX inside the grains. In addition, with increasing the aging temperature and time, the morphology of M_(23)C_6 carbides changes from semi-continuous chain to continuous network.Compared with a commercial HR3C alloy, T8 alloy has comparable tensile strength, but higher stress rupture strength. The dominant cracking mechanism of the alloy during tensile test at room temperature is transgranular, while at high temperature, intergranular cracking becomes the main cracking mode, which may be caused by the precipitation of continuous M_(23)C_6 carbides along the grain boundaries. Typical intergranular cracking is the dominant cracking mode of the alloy at all stress rupture tests.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

The 15th Global Foundry Sourcing Conference 2014held in Qingdao China

Organized by Suppliers China Co., Ltd and co-organized by the National Technical Committee 54 on Foundry of Standardization Administration of China, the 15th Global Foundry Sourcing Conference 2014 （hereinafter referred to as FSC 2014） was successfully held on Sep. 23rd in Grand Regency Hotel, Qingdao. More than 500 delegates from home and abroad attended this conference, including over 130 purchasers from 20 countries and 380 domestic and foreign suppliers.     

Secondary Recrystallization Behaviors of Grain-Oriented 6.5 wt% Silicon Steel Sheets Produced by Rolling and Nitriding Processes

By rolling and nitriding processes, 0.23- to 0.3-mm-thick grain-oriented 6.5 wt% silicon steel sheets were produced. The core losses of grain-oriented 6.5 wt% silicon steel at frequencies ranging from 400 Hz to 20 k Hz were lower than that of the grain-oriented 3 wt% silicon steel with the same thickness by 16.6–35.8%. The secondary recrystallization behavior was investigated by scanning electron microscopy, energy-dispersive spectroscopy, and electron backscattered diffraction. The results show that the secondary recrystallization in high-silicon steel sheets develops more completely as the nitrogen content increases after nitriding, secondary recrystallized grain sizes become larger, and the sharpness of Goss texture increases. Because more {110}116 grains in the subsurface and the central layer of the sheets have a lot of 20°–45° high-energy boundaries in addition to Goss grains, {110}116 can be the main component through selective growth during secondary recrystallization when the inhibitor quantity is not enough and inhibitor intensity is weaker. The increases in nitrogen content can increase the inhibitor intensity and hinder abnormal growth of a mount of {110}116 grains and therefore enhance the sharpness of Goss texture.     

Laser Cladded TiCN Coatings on the Surface of Titanium

Laser cladded coatings of TiCN were produced on the surface of titanium. To obtain the optimal techniques, several conditions were tested by varying the laser scanning rate. The choice of shielding gas was also studied. The cladded coatings were then evaluated from the surface mechanics point of view based on their microhardness. The microstructure of some interesting samples was investigated by optical micrographs (OM). The results showed that under the condition of fixed pulse frequency and pulse width, the laser scanning rate and the shielding gas are the main factors influencing the components of coatings. TiCN coatings were decompounded and oxidized during the cladding process in the condition of no shielding gas of N2. X-ray diffraction results indicated that the composite coatings composed of TiCN, TiC, Ti2N, and TiO2 were produced using appropriate techniques. The results indicated that the best condition in terms of the surface microhardness is obtained when the scanning rate is 1.5mm / s, the pulse frequency is 15Hz, the pulse width is 3.0ms, and N2 is chosen as the shielding gas. The microhardness of the composite coatings is about 1331kg · mm - 2, which is about 4 times that of the substrate. The optical micrographs indicated that the cladding zone is made up of TiCN, TiO2, and some interdendritic Ti, but the diffusion zone mainly consists of the dendrites phase, and the cladded depth is about 80?滋m, which is more than 2 times that of the laser nitrided sample. There were no microcracks or air bubbles in the cladded sample, which was cladded using the above optimal techniques.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

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正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis