Xingwen YU
,
Chunan CAO
,
Chuanwei YAN
,
Zhiming YAO
材料科学技术（英文）
A new method for corrosion protection of Al-based metal matrix composites (MMC) was developed using two-step process, which involves anodizing in H2SO4 solution and sealing in rare earth solution. Corrosion resistance of the treated surface was evaluated with polarization curves. The results showed that the effect of the protection using rare earth sealing is equivalent to that using chromate sealing for Al6061/SiCp. The rare earth metal salt can be an alternative to the toxic chromate for sealing anodized Al MMC.
关键词:
Ye WAN
,
Chuanwei YAN
,
Chunan CAO
,
Jun TAN
材料科学技术（英文）
A laboratory study of the atmospheric corrosion of carbon steel deposited with (NH4)2SO4 in the presence of SO2 is reported. The different levels of (NH4)2SO4 (0, 15, 30, 45, 60μg·cm2 were added on the surface of the samples before the exposure. The corrosion was investigated by a combination of gravimetry, Fourier transform infrared spectroscope and scanning electron microscopy. A detailed knowledge about the corrosion products was acquired, both quantitatively and qualitatively. The results show that the metal loss increased and the increasing tendency of corrosion rates slowed down with the increasing exposure time. The phase constituents of the corrosion products are mainly α-FeO(OH), γ-FeO(OH), and δ-FeO(OH).
关键词:
Steel A3
,
null
,
null
,
null
,
null
Xingwen YU
,
Chuanwei YAN
,
Chunan CAO
材料科学技术（英文）
Technological process of rare earth sealing anodized LY12 (2024) alloy is introduced. Corrosion behavior of the film was studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results showed that the coating remained passivity at the potential range from the open circuit potential (-780 mV) to –250 mV in NaCl solution. When the potential exceeded -200 mV, corrosion reaction happened on the coating. the results of EIS analysis was consistent with the results of polarization curves.
关键词:
LY12 alloy
,
null
,
null
,
null
Xingwen YU
,
Chuanwei YAN
,
Chunan CAO
材料科学技术（英文）
The rare earth sealing procedure of the porous film of anodized aluminum alloy 2024 was studied with the field emission scanning electron microscope (SEM) and X-ray energy dispersive spectroscopy (EDS). The results show that RE solution can form cerium oxide/hydroxides precipitation in the pores of the anodized coating at the beginning of sealing. At the same time, the spherical deposits formed on the surface of the anodized coating created a barrier to the precipitation of RE solution in the pores. When the pore-structured anodizing film is covered all with the spherical deposits, RE conversion coating will form on the surface of the anodized coating. The reaction of the coating formation was investigated by employing cyclic voltammetry. The results indicate that accelerator H2O2acts as the source of O2 by carrying chemical reaction in course of coating formation. In the mean time, it maybe carries electrochemical reaction to generate alkaline condition to accelerate the coating formation. The porous structure of the film is beneficial to the precipitation of the cerium hydroxides.
关键词:
Rare earth sealing
,
null
,
null
邹元爔
,
赵彭年
,
曹兆民
金属学报
利用石灰的加碳还原反应,设计了一个新的研究方法,以直接测定液态高炉型渣中CaO的活度.这一方法的成功,依靠溶剂金属的正确选择以降低熔液中钙的化学位,而使金属钙量提高到可以用化学分析测定的水平.我们估计钙在锡稀溶液中的活度系数很小,可能符合于我们的要求,因此研究了下列反应:CaO+C(石墨)=Ca(锡)+CO(气).以测定液态CaO-SiO_2和CaO-Al_2O_3-SiO_2渣中CaO的活度,在上式中符号下波纹线表示溶于渣中的组分,直线表示溶子金属中的组分,下同.对于CaO-Si0_2系,应用Gibbs-Duhem关系从CaO活度值算出了SiO_2的活度值,并根据一个统计力学模型讨论了活度曲线的形状.从CaO-Al_2O_3-SiO_2系的研究结果,可知在所研究的整个碱度范围內,渣中存在10%Al_2O_3都使CaO的活度增加;当Al_2O_3为20%时,则对CaO活度的影响视碱度不同而异.对Al_2O_3的这种行为,根据炉渣的离子结构理论提出了解释.
关键词:
张子青
,
周继程
,
邹元燨
,
田彦文
金属学报
本文以Sn为溶剂金属,直接用“渣-金属”化学平衡法,在较大组成范围内测定了CaO-Si0_2-Al_2O_3三元熔渣中CaO的活度。成功地用图示推测法推测了较难直接获得实验结果的低CaO浓度范围内CaO的活度。应用本文实验结果和数据分析得到了该渣系中较全面的等CaO活度曲线图,并对Al_2O_3在该渣系中的酸碱性行为进行了探讨。
关键词:
刘彦海
,
段百泉
,
胡希东
耐火材料
doi:10.3969/j.issn.1001-1935.2007.04.012
为了降低真空冶炼用MgO坩埚因MgO的高温不稳定性对冶炼合金造成的影响,同时发挥CaO的脱硫作用,以w(MgO+CaO)>97%的MgO-CaO熟料为原料,在对MgO-CaO熟料进行水化试验和烧结试验研究的基础上,研制了MgO-CaO坩埚,并且与CaO坩埚一起对一种纯金属和同材质的高温合金进行了对比冶炼试验.结果表明:MgO-CaO熟料的抗水化性远高于石灰熟料的;在添加适当种类和数量的烧结助剂后,MgO-CaO熟料的可烧结性明显改善;MgO-CaO坩埚的冶炼效果达到甚至超过了CaO坩埚.
关键词:
真空冶炼
,
坩埚
,
CaO
,
MgO-CaO
