镁改质对Y1Cr13易切削不锈钢中硫化物的影响

为了研究镁对Y1Cr13易切削不锈钢中硫化物的改质作用,采用金相显微镜、Image-Pro Plus图像分析软件、扫描电子显微镜、FactSage热力学软件分析了添加镁前后钢中硫化物的分布规律、整体形貌以及析出条件。结果表明,向Y1Cr13易切削不锈钢中加入一定量的镁可将Al2O3改质成细小弥散的Al2O3·MgO,钢中典型硫化物MnS在钢液凝固末期会以其为形核质点析出,析出温度为1448℃,形成的MnS-Al2O3·MgO复合夹杂物具有外软内硬的结构,这种结构使得MnS在轧制过程中不易变形,在轧材中仍然保持球状或椭球状,并且随着镁质量分数的提高,Al2O3·MgO的析出温度区间越大,其析出量越多,对MnS形态的改善也越明显;硫化物评级由未改质前的细系5.5、粗系4.5下降到改质后的细系3.5、粗系1.0,并且随着其质量分数的提高,评级进一步下降至细系2.5、粗系0.5,轧材成材率由原来的70%提升至90%。因此,适当提高镁的添加量有利于提高其改质效果。

镁处理对45钢中夹杂物的改质效果

采用光学显微镜、扫描电子显微镜、非水溶液原位电解方法对比分析了镁处理(0.0006%Mg)和钙处理(0.0010%Ca)45钢中夹杂物类型、尺寸、分布及形态变化。研究表明,相对于传统的钙处理工艺,45钢中加入一定量的镁后,钢中的Al_(2)O_(3)转变为细小弥散的MgO·Al_(2)O_(3),MnS在凝固末期以MgO·Al_(2)O_(3)为形核质点,形成外软内硬的MnS-MgO·Al_(2)O_(3)复合夹杂物;这种结构的夹杂物不易变形,在轧制过程中仍能保持球状或纺锤状,可使A类硫化物、B类氧化铝的评级均得到改善;钢中夹杂物更加弥散分布,钢中0~4μm^(2)小尺寸夹杂物比例上升,钢中夹杂物形貌的改善,更有利于提升钢材的性能。

镁对21-4N气阀钢中碳化物的影响

为了探究不同镁含量对21-4N气阀钢中液析碳化物的影响规律,采用实验室高温电阻炉冶炼了不同镁添加量的21-4N气阀钢,借助蔡司金相显微镜、扫描电子显微镜、电解腐蚀等方法开展研究。结果表明,随21-4N钢中Mg含量的增加,碳化物平均最大尺寸及面积占比均先减小后增大。添加微量的镁有助于改善钢中富Cr型液析碳化物的尺寸和分布,镁的质量分数为1.6×10^(-5)时,液析碳化物平均最大尺寸为60.55μm,面积占比10.43%,在钢中多呈颗粒状分布,连续性被破坏,其原因是镁元素在晶界处的偏聚,能够抑制C、Cr等合金元素的扩散,阻断碳化物连续生长,从而达到细化碳化物尺寸的效果。

Electrokinetic and Flotation Investigations of Surface Properties Modification of Magnesite and Serpentinite Using Biosurfactants and Surfactants

This paper presents some results of zeta potential measurements performed into biosurfactant adsorption onto magnesite and serpentinite surface. Zeta potential and isoelectric point measurement of magnesite and serpentinite particles before and after interaction with biosurfactant broth solution and activator （nickel（II） ion solution） were carried out. The zeta potential results show that presence of biosurfactants changes both magnesite and serpentinite surface potential by physical adsorption which increases the hydrophobicity of mineral particles. Measurements of particles zeta potential in the presence of biosurfactant broth are relevant to the minerals flotation. Hallimod flotation response of magnesite and serpentinite as a function of collector concentration was investigated. Bioflotation test results show that at the presence of broth, the flotation separation of magnesite from serpentinite is possible.