基于声发射技术金刚石组合圆锯片干切混凝土的切削状态研究

通过自行设计的多孔与非等弧长节块组合金刚石锯片与普通锯片的对比分析,揭示组合结构金刚石锯片的切削特征.通过分析金刚石圆锯片在锯切过程中混凝土声发射信号和锯切力信号特征,得出切削速度、进给速度、切削深度对AErms峰值平均值和Z轴锯切力的影响.结论表明声发射信号的变化规律与锯切力信号的变化规律有较好的一致性.其它切削条件不变,随着切削速度的增加,声发射均方根值和切削力平均值都减小;随着进给速度、切削深度的增加,声发射均方根值和切削力平均值都增大.且自行设计的组合锯片整体性能优于普通锯片.     

锯切参数对串珠绳振动特性的影响

利用六个激光位移传感器对锯切加工花岗石过程中串珠绳的振动进行跟踪,利用MATLAB软件分析采集来的振动信号,从频率和幅值两个方面来研究锯切过程对串珠绳振动的影响.试验结果表明,串珠绳在非切削过程中的振动信号含有多个主频率,但是进入切削过程后,其主要振动频率为串珠的冲击频率.切削过程的振动信号幅值比非切削过程中振动信号的...     

花岗石锯切过程中的比能变化特征

金刚石圆盘锯已成为目前切割花岗石的最主要工具，对锯切过程进行深入地研究对于降低加工成本和提高加工效率有着非常重要的意义，能量消耗对所有加工过程都起着重要的作用，本文着重围绕在不同的加工参数下锯切花岗石时主轴电机消耗功率的变化情况，并结合比能u与单颗金刚石磨粒最大切削厚度hmax的对应关系对花岗石锯切过程中的能量特征进行量化研究。     

辅助控制器对金刚石圆锯片锯切噪声的影响实验研究

通过在线监测金刚石圆锯片锯切花岗石时的噪声,分析了锯片锯切时噪声的变化。研究了利用外加辅助控制降低锯切噪声的方法,并分析了控制器对锯片的控制力、导向轮涂层硬度和控制器安装位置对噪声的影响。实验研究表明,外加辅助控制降低了锯切噪声,合适的控制力、较低的导向轮涂层硬度可明显降低噪声,控制器安装于锯片切入端较安装于中间位置降噪效果更明显。     

基于超声振动下电镀金刚石线切割单晶硅材料的实验研究

在总结了国内外文献资料的基础上,利用自行制造的完全具有自主知识产权的超声线切割加工机床进行了加工实验,对超声线切割加工机理与工艺进行了深入研究。结果表明:施加超声作用要比普通锯切时的锯切力低,切削效率高,表面粗糙度小,同时利用ABAQUS软件进行有限元仿真分析,进一步研究了电镀金刚石线锯超声振动复合加工锯切技术的工艺规律。     

环形电镀金刚石线锯锯切工艺参数的优化

电镀金刚石线锯为环形，无惯性力，适于高速切削。本文对环形电镀金刚石线锯锯切花岗岩时的工艺参数进行了正交试验研究。分别分析了金刚石粒度、进给压力和锯丝速度对锯切效率、锯切力和锯切比的影响，分析结果表明：采用较大的金刚石粒度不会大幅度提高锯切效率，金刚石的粒度对切向锯切力的影响不大．锯切花岗岩时，要保证较高的锯切效率和锯切比，在本试验范围内，最佳工艺参数为：采用金刚石粒度为200～230^#的锯丝，进给压力为9N，锯丝速度为20m／s。     

硬脆材料的电镀金刚石线锯超声切割锯切力研究

基于冲量理论和振动加工理论,采用叠加原理建立了电镀金刚石线锯超声切割锯切力数学模型.从理论上分析了电镀金刚石线锯施加超声振动后锯切力与普通锯切力的区别,并进行了超声振动与普通锯切力对比试验研究.结果表明:锯切力的大小随线锯往复频率的提高而降低,随侧向压力的增加而增大.通过比较发现,超声振动锯切力比普通锯切力减小20%～30%.同时,对超声振动锯切过程中单颗金刚石磨粒切削运动轨迹进行了仿真分析,进一步解释了施加超声振动后锯切力减小的原因.     

基于独立分量分析理论的大块非晶合金切削信号检测

研究了在大块非晶合金切削力信号检测时利用独立分量分析法对检测信号进行去噪处理技术。在试验中，采用独立分量分析法对切削测量系统测量的大块非晶合金切削力信号进行迭代分离，从而提取出主切削力信号。并针对大块非晶合金在不同切削深度下的变形特征，运用扫瞄式电子显微镜观察了大块非晶合金的切削带特征。主切削力信号频谱的快速傅里叶变换分析表明，随着切削深度的增加，切削力信号高频部分的振幅越来越大，而大块非晶合金切削力信号高频部分是由切削带形成过程的特征引起的，并随着切削深度的增加而增加，且主切削力Fz 的频率为115 Hz。研究结果表明：采用独立分量分析法进行噪声分离后更能精确识别切削力信号中的主要信息，减少噪声造成的误判。     

基于独立分量分析理论的大块非晶合金切削信号检测（英文）

研究了在大块非晶合金切削力信号检测时利用独立分量分析法对检测信号进行去噪处理技术。在试验中,采用独立分量分析法对切削测量系统测量的大块非晶合金切削力信号进行迭代分离,从而提取出主切削力信号。并针对大块非晶合金在不同切削深度下的变形特征,运用扫瞄式电子显微镜观察了大块非晶合金的切削带特征。主切削力信号频谱的快速傅里叶变换分析表明,随着切削深度的增加,切削力信号高频部分的振幅越来越大,而大块非晶合金切削力信号高频部分是由切削带形成过程的特征引起的,并随着切削深度的增加而增加,且主切削力Fz的频率为115 Hz。研究结果表明:采用独立分量分析法进行噪声分离后更能精确识别切削力信号中的主要信息,减少噪声造成的误判。     

热锯机力能参数的理论分析与实验研究

将理想刚塑性材料的平面切削模型应用于金属的热锯切过程,分析了锯切时的切屑变形,提出一个新的剪切滑移角解;分析了锯切厚度、锯齿齿形和锯片厚度等对单位锯切功的影响;分析考察了减小锯片厚度的可能性。在(?)600固定式热锯机上进行了实验研究。实验结果与按照新的剪切滑移角所求得的理论值相符合。     

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