Effect of TiB2 addition on grain orientation of porous Si3N4-TiB2 composites by magnetic field alignment technology

Textured porous Si₃N₄-TiB₂ composites were prepared by gel-casting–assisted magnetic field alignment technology and subsequent pressureless sintering in the N₂ atmosphere. The effects of TiB₂ content on grain orientation and properties of composites were studied. Results showed that using the magnetic field of 6T, Si₃N₄ grains exhibited a high a- or b-axis orientation and TiB₂ grains exhibited a high c-axis orientation. In textured green bodies, the increase in TiB₂ content from 0 to 20 wt%, the degree of texture of Si₃N₄ grains showed a slight decrease from 0.78 to 0.71. However, the degree of texture of TiB₂ grains was maintained at about 0.98 regardless of TiB₂ content. After sintering, except for the Si₃N₄ and TiB₂ phases, new TiN and BN phases also appeared in the samples. Additionally, the sintering process promotes grain orientation of Si₃N₄ and TiB₂. Herein, the degree of texture of TiB₂ reached to about 1 regardless of TiB₂ content, meaning that the complete grain orientation formed for TiB₂. Owing to the reconstruction reaction between TiB₂ and N₂, new TiN and BN phases did not form the orientation. The increase in TiB₂ contents gradually increased the apparent porosity of the textured samples from 27.9% to 39.4%, thereby leading to the decrease in bending strength from 126.8 ± 18.8 MPa to 60.3 ± 11.2 MPa and from 105.3 ± 19.8 MPa to 53.6 ± 13.0 MPa in two directions, respectively.     

Effect of apple cider vinegar agent on the microstructure,phase evolution,and magnetic properties of CoFe2O4 magnetic nanoparticles

In the present study, spinel structure CoFe₂O₄ nanoparticles were successfully synthesized by the sol-gel auto-combustion technique. The effect of apple cider vinegar (ACV) addition as an organic biocompatible agent on the size, morphology, and magnetic properties of CoFe₂O₄ nanoparticles was investigated in detail. The phase evolution, particle size, and lattice parameter changes of the synthesized phase have been estimated by using Rietveld structure refinement analysis of X-ray powder diffraction data. Also, Fourier transform infrared spectra (FT-IR) of the samples verified the presence of two expected bands correspond to tetrahedral and octahedral metal-oxygen complexes within the spinel structure. Furthermore, microstructural observations revealed that ultrafine particles have a semi-spherical morphology. It was shown that the particles size decreased from ~45 to ~17 nm with an increase in the amount of ACV. Magnetic properties were carried out by vibrating sample magnetometer (VSM) at room temperature. Both the saturation magnetization (M_s) and coercivity (H_c) were found to be significantly dependent on the crystallite size and the amount of ACV.     

磁环表面缺陷图像分割算法的研究及实时实现

为实现小型磁环表面细微缺陷图像无监督分割,并提高分割精度与计算效率,本文提出了一种基于改进2D Gabor滤波器组的自适应阈值分割方法。首先,利用多尺度、多方向的Gabor滤波器组对缺陷图像进行滤波降噪处理,抑制目标区域与背景区域内部的噪声污染,同时增强区域间的差异性；然后,通过对处理后图像的灰度统计特性分析,根据缺陷图像的灰度均值及方差构造了灰度阈值计算公式,实现了小型磁环表面细微缺陷图像的自适应分割。实验结果表明,本文算法可快速、准确地分割缺陷并抑制噪声干扰,在分割精度、计算效率等方面也优于传统的选择迭代法、OTSU、最大熵等方法,并能够在先进的SEED-DVS8168平台上实时实现,验证了此算法的可行性与实时性。     

Study on surface magnetization recover ilmenite from titanaugite using surfactant sodium oleate

ABSTRACT

Separation of ilmenite from titanaugite was investigated by magnetic coating. By enlarging magnetic difference between ilmenite and titanaugite, ilmenite was efficiently recovered. Scanning electron microscope and vibrating sample magnetometer results indicated that magnetite selectively coated onto ilmenite surface and increased its magnetism, which resulted in different magnetic separation behavior between ilmenite and titanaugite. FTIR and contact angle measurements confirmed that the adsorption difference of sodium oleate resulted in a stronger hydrophobicity on magnetite and ilmenite than titanaugite. Interaction energy analysis illustrated that hydrophobic association interaction on ilmenite was stronger than that on titanaugite, and which led to the selective coating of magnetite onto ilmenite.     

某铜矿重介质产品提铁降硫选矿试验

某铜矿重介质产品铁品位56.24%，硫含量高达9.34%，95.72%的硫以磁黄铁矿的形式存在。为获得硫含量<2%的铁精矿，按磨矿—弱磁选—浮选原则流程对该矿石进行了选矿试验。试验结果表明，在最佳试验参数下，重介质产品经一段磨矿（-0.043 mm 85%）—1粗1精弱磁选—1粗2扫脱硫浮选流程处理，可获得产率45.23%、硫含量为1.52%、全铁品位66.50%的铁精矿，可作为后续钢铁冶炼原料的配矿使用，为此类重介质产品的利用提供技术参考。     

电子束诱导沉积钴微米线及其铁磁性

通过电子束诱导沉积的方法制备了钴(Co)微米线,并利用扫描电子显微镜(SEM)、原子力/磁力显微镜(AFM/MFM)以及物性测量系统(PPMS)等手段对Co微米线的沉积尺寸、微结构、铁磁性和电学性质进行了测试和分析。研究结果表明:Co微米线轮廓清晰、均匀性好。在不同的沉积条件下,微米线的实际长度与设定长度基本一致;实际宽度数据呈类梯形分布,半高宽是设定值的2~10倍;实际厚度低于设定厚度的60%。沉积电流对Co微米线的铁磁特性有重要影响。当沉积电流大于0.5 nA时,样品呈现出良好的铁磁特性。另外,电学性能测试结果显示Co微米线呈现绝缘特性。成功制备了室温铁磁绝缘Co微米线,这将有助于深入开展微纳尺度的结构与器件的研究和应用。     

综合物探手段在前道矿山勘查中的应用

介绍了高精度磁法测量和高密度电阻率法测量的原理,并将其应用在前道矿山勘查中。通过对数据解译圈定构造断裂两条,为矿区深部找矿提供了指导。为下一步勘探工作提供了依据。