Achieving fabrication of highly transparent Y2O3 ceramics via air pre-sintering by deionization treatment of suspension

An easy albeit quite effective deionization suspension treatment was adopted to alleviate the detrimental effects related to the hydrolysis of Y₂O₃ in an aqueous medium. Fabrication of highly transparent Y₂O₃ ceramics with a fine grain size via air pre-sintering and post–hot isostatic pressing (HIP) treatment without using any sintering additive was achieved using the treated suspensions. The hydrolysis issue of Y₂O₃ powder in an aqueous medium was effectively alleviated by using deionization treatment, and a well-dispersed suspension with a low concentration of dissolved Y³⁺ species was obtained. The dispersed suspensions were consolidated by the centrifugal casting method, and the green bodies derived from the suspension of 35.0 vol% solid loading showed an improved homogeneity with a relative density of 52.1%. Fully dense Y₂O₃ transparent ceramic with high transparency was obtained by pre-sintering consolidated green compacts at a low temperature of 1400°C for 16 h in air followed by a post-HIP treatment at 1550°C for 2 h under 200 MPa pressure. The sample had a fine average grain size of 690 nm. The in-line transmittance of the sample reached 83.3% and 81.8% at 1100 nm and 800 nm, respectively, very close to the theoretical values of Y₂O₃.     

Impacts of slip and mass transpiration on Newtonian liquid flow over a porous stretching sheet

This article focuses on analytic solutions for Newtonian fluid flow with slip and mass transpiration on a porous stretching sheet using the differential transform method and Pade approximants of an exceptionally nonlinear differential equation. The impacts of different parameters including mass transpiration (suction/injection), Navier's slip, and Darcy number parameters on the velocity of the liquid and tangential stress are discussed. A comprehensive comparison of our results with the previous one in the literature is made, and the results showed good agreement. An investigation is conducted of a combination of magnetic liquids that are conceivably pertinent for wound medicines, skin repair, and astute coatings for natural gadgets. It is found that there is a decrease in the velocity profiles and the boundary layer thickness for the case of suction.     

Making reusable reaction-bonded silicon nitride crucibles for silicon casting from kerf-loss silicon waste

Silicon kerf loss during wafer slicing and the broken quartz crucibles after silicon casting are two major solid wastes from photovoltaic (PV) industry. Especially, the recycle of kerf-loss silicon has become an urgent issue because near 100 000 t of solid wastes are generated every year. One of the most meaningful recycle routes of the kerf-loss silicon is to make silicon nitride crucibles to replace the quartz crucibles. In this study, we demonstrated how this is feasible through acid leaching refining, slip casting, and nitridation. The reaction-bonded silicon nitride (RBSN) crucibles after oxidation were found pure enough for silicon ingot growth. More importantly, they could be reused after ingot growth. With the present examples, the potential of using the kerf-loss silicon for fine ceramics is prominent.     

深部持续采动诱发断层活化滑移的灰色预测研究

深部持续采动诱发的断层活化滑移过程具有灰色系统的特征。基于某铜矿深部开采诱发断层活化滑移的现场实测数据,构建了GM(1,1)灰色预测模型。通过断层预测滑移量与实测滑移量对比分析,模型具有较高的精度。运用所构建的断层活化滑移灰色预测模型,对未来四期断层滑移量进行了预测,F2断层滑移量增速较快,与现场实际情况吻合。研究成果对于深部复杂采动影响下断层活化滑移量的预测具有重要的意义。     

基于Matlab计算滚动轴承滚滑接触内部应力分布

滚动轴承服役过程中,因滚滑现象和残余应力的存在,使赫兹接触应力不能反映材料真实的受力状态,应力分布与实验现象存在一定的偏差,因此滚滑接触下材料的内部应力计算显得尤为重要。研究一种快速、简单的材料滚滑接触内部应力的计算方法,以替代耗时长的有限元法。以现有公式为基础,通过Matlab编程计算滚滑接触下材料内部的应力场;对比不同摩擦因数下2D、3D滚滑接触内部应力场的差别。结果表明:摩擦因数越大,最大剪切应力越大,位置越接近表面,与滚动方向的夹角越小;切向摩擦力使接触点两侧最大正交切应力大小及位置发生变化;随着摩擦因数增大,一侧应力值上升,位置靠近表面,另一侧反之。提出的计算方法简单、方便,其结果为解析解,便于与残余应力或其他应力结合求出真实应力场。通过实例分析发现,真实应力场能够更好地解释实验现象,对于轴承材料组织演变的研究有重要意义。     

Mixed convection flow of a Maxwell nanofluid with Hall and ion‐slip impacts employing the spectral relaxation method

This article investigates the Hall and ion‐slip impacts on the mixed convection flow of a Maxwell nanofluid over an expanding surface in a permeable medium. The impacts of Brownian movement and thermophoresis parameters, Soret, Dufour, viscous dissipation, chemical reaction, and suction parameters, are, moreover, considered. Using the similitude changes, the partial differential equations with regard to the momentum, energy, and concentration equations are transformed to an arrangement of nonlinear ordinary differential equations, which are handled numerically utilizing a spectral relaxation method (SRM). The impacts of noteworthy physical parameters on the velocities, thermal, and concentration distributions are investigated graphically. Moreover, the numerical values of skin‐friction coefficients, local Nusselt number, and Sherwood number for different values of the mixed convection parameter $\left(\gamma \right),$ Deborah number $\left(\lambda \right),$ Hall parameter $({\beta }_{\mathrm{H}}),$ ion‐slip parameter $({\beta }_{\mathrm{i}}),$ Dufour number (Du), and Soret number $\left(\mathit{Sr}\right)$ are computed and tabulated. It is discovered that ascent in Deborah number reduces both the stream and transverse velocity profiles, while the inverse pattern is seen with augmentation in the mixed convection parameter. In addition, inverse patterns of the stream and transverse velocity profiles are seen with expansion in magnetic, Hall, and ion‐slip parameters. Besides this, the temperature and concentration disseminations decline with augmentation in Dufour number and chemical reaction parameters, respectively. It is likewise seen that both the skin‐friction coefficients lessen with expansion in Deborah number, and they ascend with upgrade in blended convection and ion‐slip parameters, while the opposite condition is noticed with augmentation in Hall parameter. Furthermore, the reverse trends of local Nusselt and Sherwood numbers are discovered with expansion in the Dufour and Soret numbers.     

印尼BAYAH电厂一次风机故障原因分析与处理

本文针对印尼BAYAH电厂一次风机设备故障，详细的分析了故障产生的原因，介绍了三点法找转子动平衡和工装车削式在线修复电机滑环工法，阐述了两种工法的原理以及实施步骤。     

Mechanism of dislocation channel-induced irradiation assisted stress corrosion crack initiation in austenitic stainless steel

The mechanism by which dislocation channeling induces irradiation assisted stress corrosion cracking was determined using Fe–13Cr15Ni austenitic stainless steel irradiated with protons to a dose of 5 dpa and strained at high temperature in both argon and simulated boiling water reactor normal water chemistry environments. Straining induced dislocation channels that were characterized by digital image correlation and confocal microscopy. Dislocation channels were found to be either continuous across the boundary, discontinuous, or discontinuous with slip in the boundary. Discontinuous channels were found to contain the least amount of strain but have the highest propensity for initiating cracks. Discontinuous dislocation channel–grain boundary intersections were shown to have the highest local stress. TEM in-situ straining of irradiated steels and atomistic simulation of dislocation–grain boundary interaction provided supporting evidence that channels that were unable to transfer strain underwent cracking. The inability of channels to relieve stress, by either slip in the adjacent grain or in the grain boundary, resulted in high local stresses and increased susceptibility to stress corrosion cracking initiation.     

Stagnation flow of hybrid nanoparticles with MHD and slip effects

The flow of hybrid nanoparticles with significant physical parameters with different base fluids in the presence of Biot number, velocity slip, and MHD effects has not been explored so far, particularly for a circular cylinder. Therefore, the current report is presented to offer a numerical solution for hybrid nanoparticles with base fluids (water and ethylene glycerol) via a circular cylinder. The physical situation is interpreted in terms of partial differential equations and is converted into ordinary differential equations after applying the similarity transformation. The results are presented in both tabular and graphical forms. The impact of physical parameters on velocity distribution is examined through graphs. The comparative results of hybrid nanoparticles for distinct base fluids as ethylene glycol and water are proposed and the hybrid nanoparticles with base fluid water seems to be greater than that of the hybrid nanoparticles with base fluid EG. The temperature profile of hybrid nanoparticles is found to be a decreasing function with growth in velocity slip parameter but an opposite trend is noted in case of nanoparticles . The skin friction and Nusselt number augmented for the increase in magnetic field, velocity slip, and nanoparticle while it shows a decreasing trend toward thermal slip parameter. For the both cases, improvement in Biot number helps enhance the heat transfer constantly.     

脱硫石膏热处理制备注浆成型模具

石灰石-石膏湿法烟气脱硫技术以石灰石为原料吸收烟气中的二氧化硫,得到石膏晶体。在控制二氧化硫排放的同时,脱硫石膏的处理与综合利用也非常重要。以脱硫石膏为原料,分析脱硫石膏的成分,通过热处理使其脱水,并表征热处理过程对石膏物理性能的影响。将热处理后的石膏用于石膏模具的制作,并最终制备固体氧化物燃料电池阳极支撑体。燃料电池测试的结果显示,脱硫石膏可以用于管式固体氧化物燃料电池的制备。