Alumina ceramic gears exhibit excellent mechanical properties as well as resistance to high temperatures and corrosion, making them suitable for extreme working conditions that traditional metal gears cannot accommodate. However, their inherent high hardness and brittleness present significant challenges in ensuring high-quality surfaces during molding and manufacturing. In this study, alumina ceramic gears were polished using a picosecond pulsed laser. By proposing a novel alternating superimposed scanning strategy, processing errors were effectively reduced, and surface integrity was enhanced. A univariate experimental approach was used to optimize the key laser processing parameters, including laser power, scanning speed, number of scans, and line spacing. The optimal combination of parameters (7 W power, 220 mm/s scanning speed, 4 scans, and 0.005 mm line spacing) was finally determined to obtain a tooth surface with a surface roughness (S-a) of 1.091 mu m (+/- 0.025 mu m). Comparative analysis showed that the surface roughness was significantly reduced by 41.93 % to 44.53 % compared with the conventional machining (1.922 mu m). In addition, the microhardness of the laser-treated tooth surface increased by 6.36 % and showed improved resistance to tooth chipping under localized high-load conditions. The enhanced surface flatness and mechanical properties significantly improve the meshing performance required for mechanical transmission systems. Notably, the laser surface treatment method significantly reduces the processing cost compared with the traditional mechanical polishing process, providing a cost-effective alternative for ceramic gear molding surface treatment process. This paper innovatively applies laser polishing directly to the tooth surfaces of actual ceramic gears featuring complex curved surfaces, thereby providing crucial process support for their practical application in high-precision transmission systems.

Carbon fiber reinforced polymers (CFRP), renowned for their superior strength-to-weight ratio, are extensively employed in aerospace, automotive, and other high-performance applications. However, their low machinability leads to rapid tool wear and compromised surface integrity. Polycrystalline diamond (PCD) tools, with their exceptional hardness and wear resistance, are well suited for CFRP cutting, and micro-texture engineering on their rake faces can markedly influence cutting behavior. This study employs finite element analysis to compare the turning performance of non-textured, circular-pit textured, orthogonal-textured, and Surface roughness and simulation of secondary cutting PCD tools. Results demonstrate that micro-textured tools substantially reduce delamination and fiber tearing, while enhancing surface quality and prolonging tool life. Among the examined designs, the orthogonal-textured tool achieved reductions of 11 % in cutting force, 17 % in cutting temperature, and 40 % in surface roughness. Additionally, the phenomenon of secondary cutting induced by micro-textures is identified, and its correlation with depth of cut is clarified. Experimental validation confirms the simulation findings, providing a theoretical basis for optimizing PCD tool texture design and improving the efficiency and quality of CFRP machining.

WC–Co cemented carbide has been widely used as machining tool material due to its good mechanical properties. Grinding is an important process in the manufacture of cemented carbide tools. When grinding tools, there are problems such as excessive grinding force, small chip space, and poor lubrication and cooling performance, which in turn contribute to surface defects such as burrs, burns, and even edge damage such as edge chipping. These problems constrain the use of carbide tools, so that the cutting force is unstable and the machining surface quality is poor when the tool is in service. In this paper, straight-line and wavy-texture patterns were designed and formed on the surface of WC–Co tools using a picosecond laser. Grinding experiments were conducted on the ablated tool using a resin-bonded diamond wheel, and surface morphology, roughness, grinding force, and cutting edge quality were evaluated. Finally, turning experiments were conducted to compare the cutting performance of the tools after conventional and laser-assisted grinding. The experimental results showed that the tools with wavy texture showed superior surface and cutting edge quality, with 53.7% and 51.2% reduction in normal and tangential grinding forces, respectively, and 66.6% maximum reduction in edge chipping for the wavy textured tools. Therefore, this study not only reveals the advantages of laser-assisted grinding in machining WC–Co cutting tools, but also provides a valuable theoretical basis for realizing high-efficiency and low-loss tool machining.

Zirconia ceramics have become an important material for the manufacture of key components in aerospace, military, energy, and other fields due to their excellent mechanical properties. However, their inherent high hardness and brittleness make them difficult to machine with high efficiency and low damage, resulting in poor surface integrity. Inspired by the ribbed groove structure of shark skin and the fractal structure of insect wing veins, two zirconia ceramics with different bionic textures are designed in this paper, and zirconia ceramic surfaces are bionically textured by using an ultrafast picosecond pulse laser. The effects of the special bionic textures on the grinding behavior of zirconia ceramics, specifically surface morphology, surface roughness, edge morphology, and subsurface damage, were investigated. The study examines the surface morphology, surface roughness, edge morphology, subsurface damage, and microscopic damage characteristics of zirconia ceramics. The experimental results show that the surface integrity of the bionic textured zirconia ceramics is better compared to the untextured surface. In particular, the bionic insect wing veins texture exhibits the best surface quality with the least sub-surface damage, and the surface roughness Sa is reduced by a maximum of 21.46%, and Sz is reduced by a maximum of 18.87%. However, the best edge morphology is exhibited by the bionic shark skin texture. Additionally, bionic texturing improves grinding lubrication and cooling conditions. The results confirm that applying bionic texturing to zirconia ceramics effectively enhances grinding performance and improves grinding surface integrity.

针对传统钢板吊运吊钩装置难取钩、易卡钩、且存在脱钩等安全隐患,为了更好服务工业生产和满足安全需求,设计了一种新型钢板自动吊钩装置.根据钢板吊运实际作业工况,通过三维建模软件Creo,建立了吊钩装置三维结构模型,其结构包括吊臂支座、矩形吊臂、T型支架、液压推杆、U形钢板吊钩、指针盘、滚动摆动指针和辅助装置等,并在Creo软件平台上进行吊钩装置的装配,检查装配体各部件间是否存在干涉,完成吊钩装置的结构设计.该吊钩装置通过液压推杆的缩短或伸长,驱动T型支架向上或向下移动,从而带动平行四边形矩形吊臂张开或收缩,实现U形钢板吊钩对大吨位、长尺寸和不同厚度的钢板顺利钩挂吊运,因液压推杆的推力作用,保证吊运工作过程中,吊钩夹紧安全可靠,能够有效防止卡钩、脱钩现象,且安装有厚度测量装置,能快速测量钢板厚度,操作简单.利用有限元分析软件Ansys,对吊钩装载状态进行受力分析,应力最大点发生在吊钩下端弯曲位置,最大值为131.86 MPa,吊钩没有出现过载情况.结果表明,吊钩装置结构设计合理,工作稳定可靠.

研究Sr、B和RE复合变质对Al-30Si合金组织与性能的影响.结果 表明,细化变质处理后的合金组织形貌发生了显著变化,α(Al)相枝晶群消失,转变为等轴晶或柱状晶;初晶硅颗粒细化,棱角钝化;针状的共晶硅变成短杆状或颗粒状,分布均匀.合金抗拉强度提高55％,伸长率增加约66％,硬度略有增加.当RE含量为0.5％-0.8％时,合金表现出较好的综合力学性能.

The detrimental effect of nanoscale hole defects on the in-plane thermal conductivity (k) was first examined for supported CVD graphene. A focused ion beam punctured equally spaced 50-nm diameter holes with different hole spacings (200, 400, and 800 nm) in supported graphene on an 8-nm thin SiO2 substrate. For the relatively low 4.91% porosity, the thermal conductivity showed a significant reduction to 212.6 W/mK from 1045 W/mK in supported graphene with no holes and even more dramatically so from 3500 W/mK in suspended pristine graphene. The thermal conductivity showed an order-of-magnitude faster reduction with increasing porosity compared to the Eucken model, which is based on the diffusive thermal transport reduction due to the void holes on the macroscale. This is believed to be attributed to the enhanced phonon scattering by the nanoscale hole edges and also by the reduced phonon passage length-scale that became comparable to the phonon mean-free-paths. Furthermore, a phenomenological fitting model is presented to comprehensively describe the k dependence on porosity, hole spacing, and the spectral dependence of the phonon mean-free-path in nanoscale holey graphene.

Objective: Cerebral venous sinus thrombosis (CVST) is a rare but life-threatening disease and an animal model for in-depth study of CVST is needed. This study aimed to develop a rat model suitable for studying clinically relevant aspects of CVST and investigating its dynamic pathophysiological changes during a 7-day period. Method: A photothrombosis method was used to create a rat sinus-vein thrombosis model. A spot size-adjustable Diode Pumped Solid State laser (DPSS) combined with thrombin injection occluded the rostral and caudal superior sagittal sinus (SSS). The model was used to evaluate pathophysiological changes at different time points over 7 days. Evans Blue dye injection was used to detect alterations in blood-brain barrier (BBB) permeability. Brain water content was also measured. Moreover, we examined changes in brain infarct volume, neurological function, as well as histology after induction of CVST. Result: CVST in rats significantly altered BBB permeability, consistent with the development of brain edema. It was accompanied by an increase in brain infarct volume and deficits in neurological function that began on day 1, peaked on day 2, and typically improved by day 7 due to the neuroprotective effects of angiogenesis and gliocyte proliferation. Conclusion: In this study, we describe a rat model that produces clinically relevant pathophysiology and pathology that will facilitate evaluation of therapeutic regimens for CVST. Furthermore, our results indicate a period of optimal clinical intervention for patients with CVST, which may reduce the probability of dependency and death. (C) 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

An artificial neural network (ANN) model was developed for simulating and predicting critical dimension dc of glass forming alloys. A group of Zr-Al-Ni-Cu and Cu-Zr-Ti-Ni bulk metallic glasses were designed based on the dc and their dc values were predicted by the ANN model. Zr-Al-Ni-Cu and Cu-Zr-Ti-Ni bulk metallic glasses were prepared by injecting into copper mold. The amorphous structures and the determination of the dc of as-cast alloys were ascertained using X-ray diffraction. The results show that the predicted dc values of glass forming alloys are in agreement with the corresponding experimental values. Thus the developed ANN model is reliable and adequate for designing the composition and predicting the dc of glass forming alloy.

The corrosion behavior of Cu50Zr40Ti10 (at. %) in HCl and NaCl solutions was investigated. The corrosion current densities icorr in HCl and NaCl solutions increase with increasing Clconcentration when the Cl- concentration is <0.5 molL-1, then continuously increase in the former and decrease in the latter. The icorr is larger in the latter than in the former when the Clconcentration is <0.5 molL-1, while inversely for in 1 molL-1 Cl- solution. The corrosion potential Ecorr decreases with increasing Cl- concentration in HCl. However, the change of the Ecorr vs. the chloride ion concentration in NaCl solution appears down-up-down.

A radial basis function artificial neural network (RBFANN) model was established for the simulation and prediction of critical cooling rate R-c of glass forming alloys. The RBFANN model was trained, learned and examined using the data from the published literature as well as own experimental data. The performance of RBFANN model is examined by the linearly dependent coefficient between the predicted R-c and the corresponding experimental/calculated one; the influence of the type of alloys and elements and the large and minor change of element content on the R-c. In addition, a group of Zr-Al-Ni-Cu metallic glasses were designed and their R(c)s were predicted by the RBFANN model. The results show that the established RBFANN model is reliable and adequate and can be used to design the composition and predict the R-c of glass forming alloys since the predicted R-c is inherent with the experimental/ calculated one. (C) 2013 Elsevier Ltd. All rights reserved.

The solidification procedures of Mg-based amorphous alloys were simulated on the basis of thermodynamics. The critical cooling rates Rcs for the formation of Mg-based amorphous alloys are obtained. Although the estimated Rc is larger than the tested one, the change tendency of the estimated and tested Rcs is coherent with each other. Thus the thermal and physical parameters difficultly measured by the experiment can be quickly calculated and are reliable for the simulation of the solidification of the alloys. The glass forming ability GFA of the alloys can be quickly estimated by using numerical simulations. The reasons for the difference between two Rcs are also discussed.

Cu60Zr30Ti10 (at.%) glassy ribbon was prepared by melt spinning. The effect of the tension on its thermal and corrosive properties was investigated by differential scanning calorimetry and electrochemical polarization experiments, respectively. The glass transition temperature T-g, onset crystallization temperature T-x, and crystallization peak temperature T-p increase with increasing heating rate, but the increasing rate of these temperatures is larger for low heating rate (5-20 K min(-1)) than for rapid heating rate (20-80 K min(-1)) for the as-cast and tensile ribbons. The T-g for the tensile ribbon is smaller than that for the as-cast one in studied heating rates. The T-x and the T-p for the tensile ribbon are smaller than those for the a-cast ribbon when the heating rate is less than 80 K min(-1), while inversely when the heating rate reaches up to 80 K min(-1). There is a critical heating rate for the characteristic temperatures of the tensile ribbon surpassing those of the as-cast one. The heating rates are estimated to be 114.7 K min(-1) for T-g, 65.3 K min(-1) for T-x, and 64.9 K min(-1) for T-p, respectively. In addition, the activation energies for the glass transition and the crystallization decrease. On the other hand, the corrosion potential is larger in 0.5 M H2SO4 than in 1 M chloride-ion-containing solutions for the as-cast and tensile specimens. However, the corrosion current density is smaller in the former than in the latter for the tensile and as-cast specimens. After the tension, the corrosion potential sharply increases in 0.5 M H2SO4 and decreases in 1 M chloride-ion-containing solutions. The passive potential decreases and the pitting corrosion can be observed in 0.5 M H2SO4. The potential for the sharp decrease of the current density decreases in 1 M HCl, and maintains almost the same in 1 M NaCl. The corroded surface micrographs in all studied solutions are remarkably changed. In addition, the difference of corrosive behavior in 0.5 M H2SO4, 1 M HCl, and 1 M NaCl is also discussed. (C) 2013 Elsevier B.V. All rights reserved.

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Cu50Zr40Ti10 (at%) glassy ribbon was prepared by melt spinning. The effect of mechanical tension on its thermal and corrosive properties was investigated by differential scanning calorimetry and electrochemical polarization experiments, respectively. After mechanical tension, the crystallization temperature and the crystallization enthalpy almost maintain the same, while the relaxation temperature and the glass transition temperature decrease. In addition, the activation energy of the glass transition decreases from 74.8±1.7KJmol−1 to 71.0±1.9KJmol−1. The activation energy of the relaxation decreases from 70.0±4.4KJmol−1 to 50.5±3.8KJmol−1 at low heating rate, while increases from 186.1±9.4KJmol−1 to 289.4±9.4KJmol−1 at rapid heating rate. On the other hand, corrosion potentials polarized in all studied solutions sharply decrease, while the corrosion current densities increase. The pitting corrosion vanishes in 1M chloride-containing solutions. The passive potential and the passive current density both decrease in 0.5M H2SO4. The corroded surface micrographs in all studied solutions remarkably change. In addition, the difference of corrosive behavior in 0.5M H2SO4, 1M HCl, and 1M NaCl is also discussed.

Structural and thermal sensitivity of Cu(60−x)Zr(30+x)Ti10 (x=0, 5, and 10 at%) amorphous alloys to the application of tension was investigated. The structural sensitivity to tension decreases with increasing Cu content. The crystallization enthalpy increases with increasing excess free volume. The characteristic temperatures of the tensile samples can surpass those of the as-cast ones under a critical heating rate which differs in the Cu content. The increase of the excess free volume significantly influences the glass transition and crystallization procedures.

Zr-Al-Ni-Cu bulk metallic glasses (BMGs) were developed and their fragility parameters (m) were calculated by Arrhenius and Vogel-Fulcher-Tammann (VFT) equations. The results show that the m values of the Zr-Al-Ni-Cu BMGs derived by Arrhenius equation are in agreement with the corresponding m values derived by VFT equation. These Zr-Al-Ni-Cu BMGs characterize in low m values. The low m values for these BMGs would be due to their network microstructures. In addition, the m values of Zr-Al-Cu-Ni BMGs could be obtained by regulating Zr content. The composition of Zr-Al-Cu-Ni BMGs with the lowest m value would be near 54%Zr (mole fraction) because the m value about 13 of Zr54Al13Cu18Ni15 BMG is the lowest among these Zr-Al-Ni-Cu BMGs developed.

Cu55Zr35Ti10 (at%) glassy ribbon was prepared by melt spinning. The effect of the tension on its thermal and corrosive properties was investigated by differential scanning calorimetry and electrochemical polarization experiments, respectively. After the tension, the crystallization procedure including crystallization temperature and crystallization enthalpy of Cu55Zr35Ti10 metallic glass hardly maintains the same, while the relaxation temperature and glass transition temperature decrease. In addition, the activation energies of the glass transition and the relaxation decrease. On the other hand, corrosion potentials polarized in all studied solutions sharply increase, while the corrosion current densities decrease. The corroded surface micrographs in all studied solutions are remarkably changed. In addition, the difference of corrosive behavior in 0.5M H2SO4, 1M HCl, and 1M NaCl is also discussed.

Cu50Zr40Ti10 bulk amorphous alloys were fabricated by hot pressing gas-atomized Cu50Zr40Ti10 amorphous powder under different consolidation conditions without vacuum and inert gas protection. The consolidation conditions of the Cu50Zr40Ti10 amorphous powder were investigated based on an L9(34) orthogonal design. The compression strength and strain limit of the Cu50Zr40Ti10 bulk amorphous alloys can reach up to 1090.4 MPa and 11.9 %, respectively. The consolidation pressure significantly influences the strain limit and compression strength of the compact. But the mechanical properties are not significantly influenced by the consolidation temperature. In addition, the preforming pressure significantly influences not the compression strength but the strain limit. The optimum consolidation condition for the Cu50Zr40Ti10 amorphous powder is first precompacted under the pressure of 150 MPa, and then consolidated under the pressure of 450 MPa and the temperature of 380 °C.