Ca对共晶Al-Si合金磷变质效果的影响

利用金相和电子探针微量分析仪(EPMA)等手段研究了共晶Al-Si(ZL109)合金熔体中Ca对Al-Si合金变质效果的影响.结果表明:合金中的Ca能使P变质失效,甚至出现类似Na变质处理的效果.分析表明:Ca能与合金熔体中的P形成比AIP更稳定的CaxPy化合物,从而抑制了P变质作用的发挥;C2Cl6精炼可使CaxPy化合物分解,重新形成AlP,从而使P变质效果得以恢复.     

Mg对共晶Al-Si合金磷变质效果的影响

研究结果表明,经过磷变质处理的共晶Al-Si合金中加入1.2%的Mg后,磷变质效果变差,甚至出现类似钠变质处理的特征.分析认为:Mg能与合金熔体中P形成比AlP更稳定的化合物,抑制了磷变质作用的发挥;在加入Mg再进行变质处理的情况下,变质效果良好.     

Al-P中间合金对共晶和过共晶Al-Si合金的变质机制

探讨了Al—P中间合金对共晶及过共晶Al—Si合金的变质特点，P在Si相中的存在形式、分布规律及变质机制．实验表明，Al—P中间合金可有效地细化过共晶Al—Si合金中的初晶Si，使该合金的σb．20℃和δ20℃分别提高19．0％和125％．对共晶型Al—Si合金而言，Al—P中间合金可促使析出细小的初晶Si，获得过共晶型组织，并将针片状的共晶Si变为短杆状，从而使该材料的σb，20℃和σb，300℃分别提高11．1％和18．9％．Al—P中间合金加入到过共晶Al—Si合金中，P主要以AlP形式存在于初晶Si内部；加入到共晶Al—Si合金中的P分别以AlP和原子态P存在于Si相内．P对过共晶Al—Si合金变质是以AlP异质形核机理为主；而P对共晶Al—Si合金的变质是以AlP异质形核和原子态P影响Si相形态两种机制共同作用的结果．     

锶对铝硅合金磷变质的影响

利用金相和电子探针微成分分析仪(EPMA)等手段研究了共晶Al-Si(ZL109)合金熔体中Sr对P变质效果的影响。结果表明:Sr的加入量小于0.175%时,对P变质没有影响。分析表明:在Al-Si合金中心仍是作为核心的AlP,其周围是Sr与P、Al、Ca、Mg生成的多元化合物,此多元化合物与初晶硅的晶格结构相似。     

过共晶铝硅合金变质处理的研究进展

综述了过共晶铝硅合金变质处理及其细化变质机理的研究进展.采用含磷化合物或含磷合金等细化变质处理过共晶铝硅合金中的初晶硅已取得了良好的效果;变质元素Na、Sr、Ba、Te、Sb、S、Y、Ca、Bi、As、Ce、Nd、RE等元素对共晶硅具有较好的细化变质作用;近年来,同时添加磷和混合稀土复合变质剂,既能细化初晶硅,又能细化共晶硅.寻求具有良好双重变质效果的复合变质剂,深入探讨变质机理已成为今后努力的方向.     

铝硅合金晶粒细化剂Al-Ti-C-P的研制

采用自蔓延＋熔铸法制备了Al-Ti—C-P晶粒细化剂，探讨了其对共晶铝硅合金的变质效果。通过扫描电镜（SEM）、光学显微镜（OM）、能谱分析（EDS）和X射线衍射仪（XRD）等手段，研究了Al—Ti—C—P晶粒细化刺的显微组织。结果表明：Al—Ti—C—P晶粒细化剂的主要相组成为TiAl3、TiC、AlP，对共晶铝硅合金具有优良的变质效果。晶粒细化剂中的TiAl2和TiC颗粒促进了AlP时共晶铝硅合金的变质效果。     

一种过共晶铝硅合金的绿色长效变质剂

RE P复合变质剂是过共晶铝硅合金的一种绿色长效变质剂。用它对过共晶铝硅合金进行变质 ,可使初晶硅结晶核心AlP长时间呈弥散状态 ,不发生聚集 ,使初晶硅最大尺寸不超过 5 0 μm ,同时可使共晶硅变成点状或杆状 ,变质效果可维持 6h。     

过共晶高硅铸造铝合金磷－稀土双重变质处理

采用正交实验方法研究了磷、混合稀土变质剂添加量和变质处理温度对Ａｌ－２２Ｓｉ－２ｃｕ－０．９Ｍｇ－１．０Ｎｉ过共晶高硅铸造铝合金变质效果的影响。结果表明：磷、稀土的添加量和磷变质处理温度对合金的变质效果起决定作用；稀土添加量对合金室温抗拉强度无明显影响，但能显著提高其高温强度；合金变质处理的最佳工艺如下：磷添加量为０．１％，稀土添加量为０．６％，磷变质温度为８３０℃，稀土变质温度为８１０℃。     

Al-Si-P中间合金对Al-25%Si合金变质细化机理研究

采用Al-Si-P中间合金对Al-25%Si合金熔体进行变质处理,研究了P含量和变质温度对初生硅尺寸和形态的影响规律。利用金相显微镜、扫描电子显微镜观察了硅相和AlP化合物的形态,X射线衍射仪测定了变质细化合金的衍射图谱和择优取向。利用最小二乘法计算了硅相的点阵常数。结果表明,当加热温度为880℃、保温时间为30 min时,在Al-25%Si合金熔体中加入0.07%P可以将初生硅相细化至50μm以下。其相关细化机理为,一方面Al-Si-P中间合金内生的AlP化合物在熔体中溶解后重新析出,增加了异质形核的核心,使晶粒细化。另一方面,P变质使初生硅相晶面间距和点阵常数增大,生长过程中的择优分布消失,抑制了晶粒长大,使晶粒尺寸减小。但随着P添加量增加以及变质温度的升高,熔体中的AlP化合物溶解度增大,不利于晶粒细化。     

Ba—P复合变质对铝硅合金初晶硅的细化作用

研究了钡、磷及钡磷复台变质对过共晶铝硅合金初晶硅的细化作用，发现钡变质可细化初晶硅的尺寸，同时使硅晶体由板块状改变为树枝状；磷变质可明显细化初晶硅，但对其形状因子改变不大；但磷复合变质综合了二者的优势。硅晶体表面有钡或钡的化合物的吸附，认为吸附抑制机制是钡变质的实质。     

MICROSTRUCTURE STUDY OF CONSTITUENT PHASES IN 2024 SERIES Al ALLOYS

X-ray microanalysis,convergent beam electron diffraction(CBD)and selected area electrondiffraction(SAD)studies on the structures and compositions of the constituent phases in2024 series Al alloys have been conducted.Partial substitution of alloying elements is found tooccur in all the constituent phases,which cause small deviations from the stoichiometric com-positions reported in these ternary compounds.The dominant phase is α-Al_(12)(FeMn)_3Si whichhas a body center cubic crystal structure with the Im■ space group and a=1.25 nm.The nextdominant phase is Cu_2FeAl_7 which has a primitive tetragonal crystal structure with theP4/mnc space group and a=0.6336 nm,c=1.487 nm.The minor phase is α'-Al_(12)Fe_3Si hav-ing α primitive cubic crystal structure with the Pm■ space group and α=1.27 nm.     

液淬和变质工艺对过共晶铝硅合金的影响

过共晶铝硅合金中的初晶硅由于晶粒粗大并且有尖锐的棱角,严重削弱了合金的机碱性能,通常我们采用变质处理工艺来改善这一现象.液淬工艺主要用于得到非晶组织,通过液淬工艺能得到超细非晶结构.如果把液淬工艺加入到变质工艺的过程中,这对实验的结果一定能产生影响.本文中,我们分别对过共晶铝硅合金采用了变质和变质液淬的混合工艺.通过实验我们证实磷元素能够显著改变组织的尺寸,通过对磷元素的扫描分析,发现磷元素不仅分布在中心,在初晶硅的内部也分布大量的磷元素,这说明了磷元素除了在异质形核中起作用外,它还可以把初晶硅分割为很多小的初晶块,不同的小初晶块生长方向各不相同,那么在宏观上观察,经过磷元素变质的初晶硅,形状上开始变得比较圆滑.如果我们在变质过程中引入液淬工艺,变质效果能得到显著的提高,结果表明晶粒尺寸变小,晶粒形状变为椭圆,这说明冷却速度促进了磷元素对初晶硅尺寸和形状的影响.     

Characterization of the surface layers formed on titanium by plasma electrolytic oxidation

This paper is concerned with the surface modification of titanium by the PEO method (plasma electrolytic oxidation) in the solutions which contain Ca, P, Si and Na. The chemical composition of the thus formed surface layers was examined by XPS and EDS. The morphology of the surface was observed by SEM. The phase composition was determined by X-ray diffraction (XRD). The adhesive strength of the oxide layers was evaluated by the scratch-test. The corrosion resistance was determined in a simulated body fluid (SBF) at a temperature of 37 °C by electrochemical methods for various exposure times.The oxide layers obtained were porous and enriched with Ca, P, Si and Na and their properties depended on the electrolyte solution and the parameters of the oxidation process. The results of the electrochemical examinations show that the surface modification by PEO does not worsen the corrosion resistance of titanium after a 13 h exposure in SBF. The electrochemical impedance spectroscopy (EIS) results indicate that the surface layers have a complex structure and that their electric properties undergo changes during long-term exposures in SBF.     

Relationship of Ca, B, and AlP in Al–12.6Si alloy

P modification has been widely used in Al-Si piston industry, but trace of Ca element has great influence on the P modification efficiency. In this work, it is found that primary Si can be heterogeneously nucleated by AlP in near eutectic Al-12.6Si alloy, but Ca element may destroy the P modification efficiency, whereas the addition of B can recover the P modification efficiency in near eutectic Al-12.6Si alloy with high Ca containing. The microstructure transformation was related to the reaction of Ca, B, and AlP. According to the thermodynamic calculation, Ca may react with AlP and form Ca3P2 compound in Al-Si alloy, whereas, when B was added into the melt, AlP could be reformed. The reaction of Ca, B, and AlP can be shown as follows: 2AlP +3Ca→Ca3P2+2Al; Ca3P2+18B+2Al→3CaB6+2AlP. In addition, with B added into the Al-12.6Si alloy with Ca and P addition, the mechanical properties were improved compared with single Ca and/or P addition.     

特性Na离子吸附剂的制备及其从钨酸铵溶液深度除钠（英文）

在Na2O-Al2O3-CaO-TiO2-P2O5体系中通过控制结晶合成了多孔吸附剂Na1.6Al0.6Ti1.4(PO4)3(NATP)。XRD分析表明,合成的玻璃体会弥散结晶为NATP和Ca9Al(PO4)7两相;通过酸浸可将Ca9Al(PO4)7相溶出,从而使主相NATP中留下大量孔道。实验研究了平衡时间、溶液pH和Na+浓度对吸附剂离子交换性能的影响。吸附动力学和平衡热力学研究表明,吸附过程可以很好地用准二级动力学方程和Langmuir等温方程进行描述。此外,在工业钨酸铵溶液中深度除钠的实验表明,除钠率高于97%,且循环实验表明该吸附剂具备良好的循环性能。     

Refining performance of Al–3Ti–0.2C–5Sr on A356 alloy and electron microanalysis of ternary Al–Ti–Sr phases

The effect of Al-3Ti-0.2C-5Sr(wt%) grain refiner on the refining performance and modification of A356 alloy was investigated using optical microscope(OM).The morphology and crystal structure of ternary Al-Ti-Sr phases in Al-3Ti-0.2C-5Sr refiner were analyzed by scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The results show that the ternary Al-TiSr phases in Al-3Ti-0.2C-5Sr refiner can promote the grain refining efficiency of A356 alloy.The ternary Al-Ti-Sr phases co-exist in two morphologies,i.e.,blocky-like phase and surround-like phase,besides,which both have the same chemical composition of Al_(34)Ti_3Sr.The crystal structure of Al_(34)Ti_3Sr is face-centered cubic,and the lattice parameter is determined to be about 1.52 nm.     

电磁搅拌Al—24%Si合金的显微组织

在常规凝固条件下,Al-24%Si过共晶合金中的初生Si为粗大的板片状,经过激烈的电磁搅拌,初生Si得到明显细化,分布均匀,绝大部分初生Si呈球团状或块状;搅拌功率越大,初生Si越细小和圆整,P变质可以强化电磁搅拌效果,在电磁搅拌条件下,Al-24%Si过共晶合金中的初生Si得以细化和球团化的主要原因是：电磁搅拌引起合金熔体对初生Si的机械破碎,摩擦作用,抑制初生Si择优生长作用,促进初生Si熟化和变质细化作用。     

电解液成分对纯钛表面微弧氧化膜结构与生物活性的影响

采用微弧氧化处理技术,在纯钛TA2表面制备了含钙磷的多孔复合氧化膜,用SEM、XRD、EPMA等分析了电解液成分对氧化膜形貌、成分、相构成及生物活性的影响。结果表明:纯钛表面微弧氧化后原位生成的含钙磷多孔性复合氧化膜由锐钛矿相TiO2,金红石相TiO2和基体Ti组成;随电解液中钙磷摩尔比(Ca/P)值的增大,表面孔洞数量增多、直径变小,膜中Ca/P值增大,锐钛矿相TiO2减少、金红石相TiO2增多;当电解液中Ca/P=5时得到的氧化膜的Ca/P值为1.528,将该样品经碱液处理后再在快速钙化溶液(FCS)中浸泡2 d后即有羟基磷灰石HA形成,表明其具有良好的生物活性。     

Establishment of water quality index （Na^＋, Ca^2＋） for purified water reused to zinc electrolysis process

The effects of Na+ and Ca2+ in the purified water on the conductivity of zinc electrolyte and the current efficiency of zinc electrolysis were studied by the alternating current bridge method and the simulated electrolysis experiments, and the water quality index of reused water was established. The results show that the conductivity of the solution and the current efficiency decrease as these two kinds of positive ions are added in the electrolyte. The effect of Ca2+ is much more remarkable than that of Na+. ρ(Na+)≤ 8 g/L and ρ(Ca2+)≤20 mg/L are the quality indexes in the zinc electrolysis process and the concentrations of Na+ and Ca2+ in the purified water reused to the process should be less than the limited values, i.e. the water quality index of the purified water should be controlled by its reused amount.